Università di Torino

THE TREES OF HISTORY Protection and exploitation of veteran trees

Proceedings of the International Congress Torino, Italy, April 1st-2nd, 2004

Edited by Giovanni NICOLOTTI University of Torino DI.VA.P.R.A. Plant Pathology Paolo GONTHIER University of Torino DI.VA.P.R.A. Plant Pathology Regione Piemonte Università di Torino

THE TREES OF HISTORY Protection and exploitation of veteran trees

Proceedings of the International Congress Torino, Italy, April 1st-2nd, 2004

Edited by

Giovanni NICOLOTTI University of Torino DI.VA.P.R.A. Plant Pathology Paolo GONTHIER University of Torino DI.VA.P.R.A. Plant Pathology ORGANIZING COMMITTEE Prof. G. Nicolotti Dr. M. Palenzona Dr. P. Gonthier Dr. R. Martinis Dr. F. Grisoni Dr. L. Persio Ms. S. Ghirardi Dr. B. Camusso MAF Servizi (Secretary)

SCIENTIFIC COMMITTEE Prof. G.P. Cellerino Prof. F. Ferrini Dr. P. Gonthier Dr. D. Lonsdale Prof. G. Nicolotti Dr. D. Nowak Dr. G. Watson

Printed by Centro Stampa - Regione Piemonte Speakers Torino, April 1st - 2 nd, 2004 3

MONUMENTAL TREES IN HISTORICAL PARKS AND GARDENS AND MONUMENTALITY SIGNIFICANCE R. Caramiello1 and P. Grossoni2 1 Università di Torino Dipartimento di Biologia Vegetale - Torino 2 Università di Firenze, Dipartimento di Biologia vegetale - Firenze

Reference to trees is present in all cultures and in all ages as a cosmic symbol and one of regeneration and resurrection and more in general of life, in its various stages: from the biblical tree of knowledge of good and evil to that of the garden of Hesperides, from the tree of liberty to that of fevers which summed up medical knowledge in the first half of the eighteenth century on the fever which afflicts mankind in a wide range of diseases. Despite these cultural values the protection of trees and woods in general has undergone over time periods of more or less marked decline. These have been linked both to a variety of reasons: a diminished sense of the sacred, reduced control over royal and community forests, changes in the use of the various species, and finally, to the different importance given to the question of the landscape. However, the might of a tree has always caught man’s attention and the species which could more easily reach considerable dimensions or age often acquired a religious meaning or a social role (for example, the oaks dedicated to Jupiter or Yggdrasil, the huge ash tree which according to Germanic-Scandinavian cosmogony had given rise to the universe and from which, after the disappearance of the world and gods, a new universe would be born or, to cite other examples, the cypress trees linked to the cult of St. Francis, the lime trees of mediaeval central Europe were often the place where justice was administered, etc.). Conservation and protection in the past were therefore derived essentially from the respect of beliefs and traditions which saw in certain trees the symbol of a guarantee, including a supernatural one, of the daily activities of survival but which, often, were also a fundamental moment in human activity (trees for fruit production for food and/or for propagation, trees for shelter, trees as signs or boundary markers and so forth). A first sign of defence of the territory and tree heritage can be found, for unified Italy, in the forestry law of 1877 and in 1939 tree heritage was finally considered in several laws which regarded historical and artistic heritage, at least as far as gardens and parks are concerned and the whole aspect of “ panoramic beauty spots considered as natural pictures” without better defining the characteristics. In the last few decades the cultural debate has led to the drawing up of national and regional legislation which include “trees” in programmes which promote the knowledge and protection of such assets. Furthermore, many of the trees which at present are indicated as monuments are part of historical parks and gardens, although the practice of safeguarding and allowing trees to grow in gardens is a relatively recent cultivation technique. In the mediaeval garden and in formal gardens (in so-called Italian and French gardens) trees of particular size were not envisaged (it is sufficient to read the theories of Alberti, Colonna, Serlio, Del Riccio, Ferrari or Dezallier D’Argenville, etc.) although the presence of a majestic tree could form an unusual and striking architectural motif such as Castello’s and Pratolino’s oak ( una Quercia di smisurata grandezza nella cui cima si sale per due scalle coperte dalle foglie ove sopra vi è uno spatio di 16 braccia di circuito cinto di lochi da sedere con una tavola nel cui mezzo sgorga un fonte chiarissimo [ ... an Oak of huge size to the top of which one can go up by two stairways cloaked by leaves where above there is a space of 16 braccio in circumference, about 10 m, surrounded by places to sit with a table in the middle of which gurgles the lightest of fountains.]. AVR, Cod. Barb. lat., n. 5341, c. 210 r., 1588. In Zangheri, 1979). For romantics, beauty is not closed in perfection: beautiful is any subject where it is possible to read the free flow of nature and history. Thus wonder for the unusualness of a tree (for size, shape, blossom, rarity, location, etc.) becomes a typical artifice of the romantic garden which is amply recommended by the theoreticians of the period because it exalts the very meaning of Nature, permanence and resistance: “A tree, alone and isolated, may be noteworthy for its own nature: it can attract attention with its immense stature, with its fine canopy, and also with its branches, and with its leaves and fruits. The more isolated the tree is, the less the eye is distracted However the gardener artist will not offer too frequently a solitary tree, unless it merits particular regard” (Silva, 1813). Certainly sustained and fostered by Romantic aesthetic reasons, admiration for the unusual tree rapidly acquires momentum, as a motif of exceptionalness, whether the tree is unusual in itself, or in habit, in colour, in growth. In the woods of our continent, where, in certain zones, man’s action has been uninterrupted for thousands of years, the monumental tree is 4 International Congress on The Trees of History not so much one which reaches the maximum dimensions as such but rather one which, for the reasons mentioned above, has been able to exceed the time limits (generally reduced) which man puts on the life of trees and thus it appears to be “outsize” compared to the standards of our cultural models. It is the tree which lives longer than normal which surprises us for its dimensions and already Horace Walpole in 1771 wrote that one does not often see a really old tree because the sense of landscape and government inspectors are two incompatible things. Walpole was certainly not what we would call today an angry environmentalist, so much so that shortly later he also wrote that in a garden, at Petworth, there are several two-hundred- year-old oaks. According to him, if there is a shortcoming in such a noble, skilfully improved fragment of nature, it is that the large size of the trees is out of proportion to shrubs and bushes.

Factors Which Influence The Monumentality A tree which for age, habit, size, rarity, cultural, historical or geographical value or for a specific connection with decorative or structural features (buildings, statues, fountains, etc.) has an intrinsic value which may be defined as a very noticeable plant (Grossoni, 2002). The monumentality of a tree brings immediately to mind the idea of exceptional dimensions (correctly speaking, monumentality qualifies the very grandeur of a specific monument); in this sense it is strictly connected to the definition of noticeable plant and it refers both to specimens of species which, potentially, may reach particular values regarding height, width of canopy and/or trunk diameter and to trees which are exceptionally “outside the norm” for species which are usually of modest size. The factors which can foster a “monumental” habit of a determined tree are multiple. They may be intrinsic (in the genome), correlated to cultivation methods or to environmental conditions. 1) Genotype. Given that a tree which reaches exceptional dimensions for its species is a clear expression of diversity, obviously the first condition is represented by the characteristics of that determined genome. The information contained in a genome is seen not only as a cause/effect relationship (i.e. genes that regulate a superior phenotype) but also as genes which induce the potentiality to grow very old by determining resistance to otherwise fatal diseases. 2) Age. It would seem obvious to state that the more a tree ages the greater it can grow in dimensions until it reaches a monumental value. Actually cultivation practices (in the woods) and maintenance, restoration or restructuring works (in an urban environment or in gardens) tend to sharply reduce the life expectancy of a tree. 3) Economic value. For centuries (and, in the Mediterranean area, for thousands of years) the woods of most of Europe (especially western Europe) have seen constant use, a fact which necessarily has limited the life of their trees and which defines periods of growth that are lower or much lower than their biological lifespan. The life expectancy of these trees has always been tied to the economics of felling. There are several examples but they regard essentially (more or less sporadic) species whose felling, until the advent of suitable tools (chain-saws), was particularly difficult and expensive (for example, juniper, yew and Cornelian cherry) or species whose wood is in little demand (e.g. Pinus heldreichii on Monte Pollino) or, finally, individual trees or clusters of trees growing in areas which are difficult to exploit (for example, the beech wood of the Riserva Integrale di Sasso Fratino in the Parco Nazionale delle Foreste Casentinesi). Likewise, individual trees were conserved when their products or exploitation determined an economic advantage (examples can easily be found throughout Italy among chestnuts and oaks with edible acorns) or had a social function (parks and hunting reserves, but also individual beeches, sycamores, cypresses or holm- oaks, linked to forms of veneration or used for shelter or protection). However, it should be pointed out that in the last few years, for both social and economic reasons, this rule of cutting any wood has started to give way to the advantage of protectionist choices (hydrogeological defence, conservation, etc.) Very recently the regulation for applying the Tuscan forestry law (Regional Law n. 39/2000), sub-section 12 (point 6) orders that “In all felling operations regarding a surface area of one hectare or more, at least one tree per hectare must be left to destine to indefinite aging for every hectare of wood cut. The specimens to be left uncut are those with the greatest diameter present in the felling area.” (Regione Toscana, Decree of the President of the Regional Government 48/R, 08.08.03). 4) Planned historical parklands. In the specific case of historical organised green spaces (historical gardens and green areas) the existence of monumental trees is mainly closely linked to the kind of arboricultural cares: trees which have not undergone drastic or periodic pruning are at a strong advantage not only for their dimensions but, above all, for their life Torino, April 1st - 2 nd, 2004 5 expectancy. In this context, historical botanic gardens, for their very aim of conservation, have undoubtedly played a role in fostering the growth of trees which today have been qualified for their “monumental” status. 5) Environmental factors. (a) location: it is easier to find that an isolated tree is identified and selected as monumental because the accentuated tapering of the trunk and the greater width and depth of the canopy make it particularly majestic and hence more easily identifiable. (b) site conditions (climatic and soil): obviously, environmental conditions which are conducive to growth favour reaching advanced age and considerable dimensions. Often isolated trees used as midday shelter for animals have enjoyed the advantage of a constant supply of fertilizers. Neveertheless, it should be remembered that trees grown in environments which are more favourable than the natural environment could show greater growth rates, rapidly reaching considerable dimensions, but they are more open to attack by wood-eating organisms (fungi and insects). (c) site conditions (pollution): widespread pollution is a recent factor linked to industrialisation and motor vehicle traffic. This complex factor is to be considered a negative element which limits the growth of veteran trees and acts as a debilitating agent which fosters the successive attack by pathogens. Moreover, the activity of certain pollutants (greenhouse effect) is attributed as being a cause of global climate change whose negative action is already clearly visible on many monumental (and ageing) trees. (d) arboricultural techniques: arboricultural techniques regard especially trees in planned historical green spaces. They can constitute an advantageous factor in the expression of genetic potentiality but can have marked negative effects, as in the case of pruning (cfr. point 4) and the application of fertilizers and irrigation which by extending the vegetative period can make the trees more open to attack by pathogens. In any case, arboricultural techniques can be advantageous for the conservation of existing veteran trees. 6) Elements for enhancing monumentality. The acquisition or enhancement of the monumental aspect may be due also to mostly casual factors, which foster the development of particular growth features. These are frequently due to the fusion of several trunks, to the rooting of lower branches and to and to the emission of aerial roots. (a) fusion of trunks: various trunks (suckers, branches or trunks growing closely together) “fuse” and graft; in this way trunks of particular dimensions and shapes are created (for example, the legendary Etnean chestnut known as the “Chestnut of one hundred horses” and the Taxodium mucronatum Ten. of Santa Maria del Tule with a diameter of 12 m, etc.). (b) rooting of drooping branches at the base: rooting of branches of lower crown leads to the formation of a cluster of boles which can reach monumentality dimensions. (c) aerial roots and buttressing: the emission of aerial roots and the development of buttressed roots are features which can exalt the sense of monumentality of a tree (e.g., in Palermo the Ficus magnolioides of Piazza Marina and of the Botanic Gardens). Further factors which intervene in the concept of monumentality and are included in the definition cited at the beginning of the treatise refer to cultural and historical values which, very frequently, but not always, accompany the extraordinary dimensions and age of certain specimens. Indeed some have a precise historical motivation that connates them as monuments: for example, the Goethe palm in Padua, the date of planting is known (1585) as is the origin of the name, which dates to 1786 when, almost two centuries later, Goethe admired it and studied it, drawing inspiration for his evolutionary intuition expressed in the essay “The metamorphosis of plants”. Other great trees, even in a historical garden, may not be accompanied by such a well known written history that documents when the tree was planted or the reason for the choice or that connects it with personalities and events. Certainly for this reason the Corpo Forestale dello Stato (National Forestry Service - CFS) lists that are today available, albeit rich, should be integrated with information that can come from herbarium or archive studies conducted in Botanic Gardens and similar cultural and historical contexts.

Monumentability And Botanical Species It is not easy to make an analysis of the taxa to which Italian monumental trees belong in that a general official census that is representative of our country has never been performed. The only inventory on a national scale, decided and performed by an authoritative and representative organisation, is that conducted by the Corpo Forestale dello Stato which started in 1982. It is on the basis of this study that a selection was published in the early 1990s (Alessandrini et al., 1990-91) and is available on the official Corpo Forestale dello Stato website. 6 International Congress on The Trees of History

Most Italian regions have drawn up inventories for their own territories; similar initiatives have been undertaken and implemented also by individual provinces and municipalities. Therefore there are lists which are more or less comprehensive and more or less correct; however, even today there is no list that is exhaustive and authoritatively reliable. In fact the CFS inventory has given relative importance to historical urban and out of town public green spaces. It is not even possible to complete this list using regional, provincial and municipal lists in that the criteria of evaluation are different as the fundamental factor in the decision of giving a tree the title “monumental” still remains a subjective one linked above all to the emotion that a certain tree creates in the observer. Moreover the discriminatory threshold between ordinariness and monumentality tends to be also in function of the surface area of the territory in hand. The “task” of our report is to examine certain aspects of the most common taxa represented in so-called monumental trees. For this reason our starting place was the only national list available. Actually, as the list published on the Corpo Forestale dello Stato website is more comprehensive than that published in the two volumes by Alessandrini and co-workers (1990-91), we refer to the web version. The inventory has covered 1255 trees belonging to 143 taxa (species, subspecies, cultivars and hybrids) belonging to 76 genera (21 Pinophyta and 55 Magnoliophyta). Of the 143 taxa 65 are included in Italian flora and 78 are exotic. In addition to the use, in some cases, of now obsolete nomenclature, the analysis of this inventory brings up some justifable doubts on the correct taxonomic attribution of some of the recognised specimens. We refer, for example, to the numerous specimens of Cedrus libani A. Rich. (58) and Platanus orientalis L. (37) which are a little too abundant compared to the systematically nearest taxa (Cedrus atlantica Carr. (19), C. deodara G. Don f. (22) and especially, Platanus x acerifolia (Ait.) Willd. (3). Quercus pubescens Willd. is the most represented species (211 records); far behind in second place is Fagus sylvatica L, which is mentioned 98 times (the value would rise to 113 if ornamental varieties were included). There are 99 cedars but 58.6% of these are cedars of Lebanon; among the other oaks the main species are fairly well represented (holm-oak, with 52 specimens, sessile oak with 50, turkey oak with 43 and the pedunculate oak with 36). All native deciduous oaks amount to 346 (27.6% of the total): this is certainly linked to the significance that these species had in the countryside as well as of course, to their longevity and growth capacity (it is highly probable that there have been errors in taxonomic attribution between sessile oak and downy oak). Obviously there are quite a few specimens of plane trees and giant sequoias, while we find the presence, but not in abundance, of two species which have a considerable importance in the coastal and hill landscapes of our peninsula: Pinus pinea L. and Cupressus sempervirens L. (the latter is particularly linked to episodes of devotion and religious tradition) were included in the inventory 22 and 25 times respectively. Naturally, it is given for granted that certain species are present mainly, or exclusively, in certain geographical areas; this is due to their chorology or to the fact that the climatic environmental are such as to prevent or discourage their growth in other regions. The parameters most used in defining a certain tree as monumental were undoubtedly the dimensions (height and/or circumference); however, also age, bearing, rarity and cultural values (historical, social, landscape) are all well represented. Not all the specimens included in the census are necessarily of exceptional size and several species are represented by shrubs or arborescent specimens. In order to check what the most representative taxa were, we had used some other inventories for comparison/confirmation purposes. As mentioned earlier, we used the inventory of the Corpo Forestale dello Stato and, for the sake of comparison/completion, a geographically defined sample, among the other existing lists. For the sake of simplification, we examined some surveys made in Tuscany, the region where one of the authors lives. In addition to the CFS inventory (Alessandrini et al., 1991), for the monumental trees of Tuscany we consulted some surveys made by the Lucca Botanic gardens (Poli et al.; 1992), Regione Toscana (2001) and a review made by Capodarca (2003). We then examined also the results of a survey conducted on the territory of the province of Lucca (Giambastiani, 1996). The number of specimens included in the censuses ranged from 176 (Alessandrini et al., 1991) to 347 (Capodarca, 2003; this author, however, also reports the results for Tuscany of the national census). In all, 82 taxa were reported in this region; 10 other taxa are records which have been surveyed by Giambastiani (1996) only in the province of Lucca. Compared to the taxa identified in the CFS inventory and excluding the province of Lucca, 37 more taxa have been reported while 7 are missing. On the same tree there are differences between the inventories and, in some cases, also very considerable ones both for the dimensions reported and especially for the discordant taxonomic classifications in the Torino, April 1st - 2 nd, 2004 7 genus but also (cfr. the case of Washingtonia/Jubaea) between genera. The distribution of Tuscan vegetation ranges from a dry Mediterranean to a montane environment, “summing up” in a certain sense most Italian forest climatic conditions. Likewise, the frequency trend for species of monumental trees presents many similarities with the national trend: deciduous oaks (downy oak, sessile oak, turkey oak, etc.) are the predominant species followed by cedars, beech and chestnut. Above national average we find holm-oak, cypress and stone pine in that these species are particularly used in this region as ornamental plants (historical gardens, etc.), so much so that they characterise much of Tuscan landscapes. For Piedmont the regional law which governs the census and successive protection of monumental trees is Law 50 (1995). The Corpo Forestale dello Stato inventory cites 102 monumental trees in Piedmont, of which about twenty are highlighted as specimens of exceptional value. The data are being updated as part of a wide-scale census and monitoring operation throughout the region, which has brought about, as a first step, the official “baptism” and inclusion in the appropriate regional list of five monumental trees: the Napoleon Plane in Alessandria, the Mergozzo elm (VB), the Macugnaga lime (VB), the Zelkova in the Park of Racconigi Castle (CN) and the Moncenisio ash (TO). The last two specimens have not been cited in the previous lists. The works of the Commission are obviously continuing and other reports will be arriving, including from the Turin Botanic Gardens, on some specimens which so far had not been included in the census. In the Aosta Valley 10 monumental trees have been mentioned, 4 of which particularly noteworthy. They are made up of species such as Tilia cordata Mill. in Aosta, Picea abies Karst. at Courmayeur, Aesculus ippocastanum L. at Donnas and Larix decidua Mill. at Morgex. On the other hand, in Liguria, where 18 trees have been classified as monumental, there is a predominance of exotic species, introduced into parks and gardens, including Araucaria bidwillii Hook. f. at Villa Groppallo and Jubaea chilensis Baill. at Villa Serra in the city of Genoa and Sequoiadendron giganteum (lindl.) Buchholz at Montoggio (GE). The list for Lombardy reports some 192 specimens and among these we may mention, at least for a sense of affection, that of the Scopoli Plane, planted in the Botanic Gardens of Pavia by Giovanni Antonio Scopoli, a man of great scientific repute, who the previous year had been appointed director of the Gardens. From a brief look at the lists of other regions, these too need revising, one can observe that all in all species can, if left to grow freely without the restrictions of management or maintenance, reach such dimensions that undoubtedly many of them could be classified as monumental trees. Even if we limit our inquiry to only native species, we could include conifers such as fir, spruce, larch, some pines and broad-leafed trees such as all Fagaceae (with the exception of kermes oak and a few others), elms, the nettle-tree, the sycamore maple, limes and the common ash (although the monumentality of the last two groups is perhaps more tied to Central European culture than to that of the Mediterranean). Loudon (1835-39) wrote that thanks to the extreme variability of climatic conditions in Italy every species on the planet could be grown. The claim is certainly excessive but it gives a good idea of the possibilities of growth and development of numerous exotic species in our country which have been able to reach dimensions which justify including them among monumental trees. Among the Gymnospermae the genera which are most represented and representative of the very concept of monumentality are undoubtedly Cedrus, Sequoia and Sequoiadendron; however, we should not forget Ginkgo and Cupressus (Cupressus semprevirens). The latter is noteworthy not only for the dimensions of certain species but also for the landscape value which it has in certain regions and in certain climatic environments (for example, the southern Alpine lakes). Moreover, in general we should remember some other genera of the Cupressaceae family such as Calocedrus, Thuja and Chamaecyparis which, although less frequently, are also present with noteworthy specimens. Albeit less frequent, we should note Arauciariaceae and Taxodiaceae (for example, Araucaria columnaris (Forster) Hook. and Taxodium distichum in the Reggia park in Caserta). Tulip trees, planes, ornamental forms of beech, Ficus magnolioides Borzi, Sophora japonica L. and Carya are exotic Magnoliophyta which can produce specimens of exceptional dimension. For these taxa we outline some useful aspects for understanding their salient features.

References

ALESSANDRINI A., F AZZUOLI F., M ITCHELL A., N IEVO S., R IGONI S TERN M., B ORTOLOTTI L., 1990-91 – Alberi monumentali d’Italia. 2 voll. Edizioni Abete. Roma. (L’elenco completo degli alberi e la loro localizzazione sono disponibili sul sito del Corpo Forestale dello Stato: www.corpoforestale.it/foreste&forestale/ ricerca&progetti/alberi_m/regioni.htm). 8 International Congress on The Trees of History

CAPODARCA V., 2003 – Gli alberi monumentali della Toscana. Regione Toscana e Edifir. Firenze GIAMBASTIANI M., 1996 – Gli alberi monumentali della provincia di Lucca. Inventario e proposte di conservazione. Tesi di laurea in Scienze forestali. Università di Firenze. GROSSONI P., 2002 - Metodologie per l’inventario e l’archivio della componente verde dei giardini storici. In: Grossoni P. (Ed.), Metodologie di studio per i giardini storici, Quaderni dell’Archivio n° 8, pp. 11- 17. Edizioni Don Chisciotte. San Quirico d’Orcia (SI). LOUDON J. CLAUDIUS, 1835-39 – Arboretum et Fruticetum Britannicum. London. POLI R., L IPPI A., BRACCELLI F. (EDS.), 1992 – Catalogo degli alberi monumentali dell’Italia centrale. I. La Toscana. Orto Botanico comunale di Lucca & Ministero dell’Ambiente. Lucca. REGIONE TOSCANA, 2001 – Elenco regionale degli alberi monumentali (aggiornamento al 8/11/2001). Documento non pubblicato. REGIONE T OSCANA, 2003 - Regolamento Forestale della Toscana (decreto Presidente Giunta Regionale 48/R, 08.08.03). SILVA E., 1813 – Dell’arte de’ giardini inglesi. Tomo I. Pietro e Giuseppe Vallardi. Milano. (Nuova edizione a cura di G. Guerci, C. Nenci e L. Scazzosi, Leo S. Olschki, Firenze,. 2002). WALPOLE H., 1771 – On modern gardening. London. (Saggio sul giardino moderno. Edizione italiana a cura di G. Franci e E. Zago. Casa Editrice Le Lettere, Firenze, 1991). ZANGHERI L., 1979 – Pratolino. Il giardino delle meraviglie. Vol. II. Edizioni Gonnelli. Firenze Torino, April 1st - 2 nd, 2004 9

Absolute frequency and percentage of the most represented monumental trees in Italy and Tuscany (several sources) 10 International Congress on The Trees of History

Comparison between various inventories referring to Tuscany and the Province of Lucca (various sources)

1 in the CFS website list it is indicated as 5.65 m 2 this specimen is not reported in the list on the CFS website Torino, April 1st - 2 nd, 2004 11

EVOLUTION OF TREE LANDSCAPING IN HISTORICAL PARKS AND GARDENS M. Devecchi Dipartimento di Agronomia, Selvicoltura e Gestione del Territorio. Università di Torino

1.Foreword Since the origins of history, man has developed the need to organize and mould the surrounding space, in both amusing-recreational and utilitarian terms, transforming and changing it in a pleasantly livable environment. A garden is a space that symbolizes Eden, where we were born, but from which we were driven away. A garden represents the myth of the “sacred wood”, i.e. of the magical place or enchanted and remote microcosm, where everything is possible and achievable. The tree, as a primary component of the garden, has always represented the symbol of stability and is associated with the concepts of growth, development, protection, longevity, radication, and age. Planting a tree has always been an act full of spiritual meaning, as it is a faithful mirror of man’s existence. The big tree invites to meditation and induces respect and wonder that turned to a deep religious feeling in many peoples and civilizations. “The garden art” emerges naturally from this religious thought, linked to the idea of creation and organization of the natural element in an anthropical vision, i.e. in a landscape arranged according to a rational criterion. A garden has, thus, the primacy of being the aesthetical, historical, and cultural identity of a place. Not only a garden, but the very landscape appears as a metaphor of human deeds, that modify it continuously following his demands and needs. Each tree, group of plants, avenue, thicket and spontaneous hedge, as well as the heritage of urban green and country green, holds a landscaping function of extraordinary importance. A tree characterizes, carves, and determines the colour and often the shape of landscape. In particular, the trees of monumental interest, as elements that participate strongly in the characterization of places, represent elements able to “resist” to an increasing landscape banalisation and simplification. It is renowned how the rural landscape even in the Piedmontese reality, has found in the trees the characteristic features that can be referred to well identifiable plantation and exploitation models. An example of this are, for instance, the trees around farms, the rows and single specimens placed to mark the borders between holdings or along water courses and ditches. Old prints or paintings are of great interest for this purpose, as they depict the landscapes of some centuries ago, where one can see the frequency with which oaks are illustrated for the majestic architecture of their trunk and branches. Landscape safeguard and exploitation can be addressed also towards a field until now not sufficiently explored as that of the tree heritage, considering the importance of such elements in the characterization of the landscape, besides of parks and gardens. In a view that does not end only in the aesthetical- perceptive consideration of landscape, another aspect of the trees of extraordinary importance is the fact that they are the result of a whole series of environmental adaptations and of the capacity to respond to external conditionings that make them the depositary of a remarkable heritage of scientific knowledge.

2.The use of trees in ancient times Under the word garden, we usually mean a piece of ground in which ornamental plants and flowers are grown. Really, the oldest descriptions talk of a garden as a vegetable garden, or an “orchard”, thus having utilitarian scopes. In the mythological imagination, Persian paradises are enclosures and places where tame animals, that do not attack man, are kept as signs, symbols, and memory of the old “sacred wood”. In the Egyptian civilisation, the garden was conceived both as a place of relaxation and as a productive place for growing grapevines, date palms and vegetables and so, with the typical feature of the “orchard-vegetable garden”. The Egyptian garden, known through many paintings found inside tombs, was characterized by a strictly planned design: around a rectangular basin, or even more pools, herbaceous and shrubby plants were placed, followed by the tall trees. Among the evidence found, remarkably important are the paintings on the walls of the temple of Tuthmosis III at Karnak, illustrating 256 different species, that underline the particular interest of the Egyptian culture for the study of botany. Among the most common plants grown there are trees of productive and ornamental interest, such as palms (Phoenix dactylifera), tamarisks (Tamerix gallica), fig trees (Ficus carica), pomegranate trees (Punica granatum), olive trees (Olea europaea), almond trees (Prunus amigdalus) and grapevines (Vitis vinifera). In the civilisation of ancient Greece, the garden was not considered as a real kind of art, it was characterized instead in a functional and productive way. The old garden of the literary tradition, handed on from the Greek world, is described in the 7th book 12 International Congress on The Trees of History of the Odyssey, where Ulysses arrives when he approaches the town of the Phaeacians and is hosted in the royal palace of Alcinous. It is a meticulously arranged garden, as often this image of the Greek world is, like a mixture between garden and orchard. It is a fructiferous place, sprayed with crystal water and decorative elements. Greek mythology refers to the locus amoenus: a magic place where the genius loci reigns and where one searches the harmony between man and landscape, inherent in nature. Such were the woods close to the sanctuaries, where plane trees (Platanus orientalis), elms (Ulmus minor), alders (Alnus glutinosa), and cypresses (C. sempervirens) are grown, as well as fruit trees. The woods in the neighbourhoods of the towns were instead different, they were planted in regular rows. In Athen’s agora, for example, in correspondence with the temple of Hephaestus, there was a geometrical garden, in which the rows of small trees repeated the setting of the temple’s columns. The Romans had the custom to name a certain tree species to the divinities, that they believed were born from trees or under trees, symbolizing with them their attributes; so the oak (Quercus robur), as the expression of strength and vigour, was consecrated to Jupiter for its majesty and superiority over the trees of the forests; the holm oak (Q. ilex) was consecrated to Pan and with this tree the ancients forecasted the deeds of heaven (also the Etruscans considered the holm oak divining and, with its branches shaken towards the sky, they called for the rain to make the seed grow); the elm (U. minor) was dedicated to Morpheus, as it invites to relax, because under its shadow sleeping is sweet; the ash tree (Fraxinus excelsior) was linked to Mars, as it was useful to make lances; the cypress (Cupressus sempervirens) was dedicated to Pluto and was put on the front door as a funeral sign; the white poplar (Populus alba) was connected to the Muses and to Hercules; the black poplar (Populus nigra) was joined to the Heliades in memory of Phaeton, their brother; the weeping willow (Salix babylonica) was consecrated to Juno, because she was born and brought up among these melancholy trees; and finally the laurel (Laurus nobilis) that, as a symbol of triumph, health, cheerfulness and also safety, was dedicated to Tiberius. In Italy at the time of the Romans there was no spring, river, famous place, and forking of a public road that had not its sacrarium with a tree; The most solemn acts of the life of peoples or of the individuals were made in the shade of big trees. Around certain consecrated trees a fence was built in which not everybody could enter; the enclosed space became sacred and the ground a religious place (AA.VV., 1990). Especially starting from the Augustan age, the gardens in Rome reached the highest forms of artistic expression, also as a consequence of the fact that the vegetation became architecture, through the practice of the ars topiaria. The specialists of the ars topiaria tried to make the garden habitat lively, operating not much with the colours, but with the shapes of the plants (Grimal, 1990). So these were pruned in the most curious shapes and placed so as to create diverse shades of green of the foliage of trees and shrubs (Fariello, 1967). The remaining decorativity came from fruit trees, thanks to their abundant blossoming, such as in the peach trees, a tree imported from Orient by Lucullus, together with local species, such as cherry and apple trees. Fundamental is the information handed on to us by Pliny the Elder in Naturalis Historia about the commonly used plants: oak (Q. robur), holm oak (Q. ilex), and pine (Pinus pinea) were used in big parks; the cypress was used to make protective curtains in gardens; linden (T. cordata), plane tree and palm were instead employed mostly in the city; laurel, box (Buxus sempervirens), myrtle (Myrtus communis) were preferred, because easily shaped; but there was space also for alder, oleander (Nerium oleander), ivy (Hedera helix), fruit trees and flowers: roses (Rosa spp.), violets (Viola odorata), anemones (Anemone nemorosa), hyacinths (Hyacinthus orientalis), and other flower species.

3. The tree in the medieval and Arab garden In the Middle Ages, the garden called Hortus conclusus became a place of meditation and spiritual retreat. Among the most useful literary sources for the comprehension of the medieval garden, fundamental is the treatise of agriculture De Ruralium Commodorum, written in 1305 by Pietro De’ Crescenzi, a jurist of Bologna, close to the Angevin court of Naples. In this work one can understand how the garden, divided geometrically by beds separated by alleys covered with pergolas, was often marked by the presence of the “Pomarium”, composed of fruit trees set in rows. In the Hortus conclusus there was place for flowers and fruits full of symbolic meanings, such as the rose, the Virgin’s flower, the lily, symbol of purity and poverty; the pomegranate (P. granatum), a metaphor of the unity of the church, and, among the trees, the palm (P. dactylifera and Chamaerops humilis), symbol of justice, the fig tree (F. carica), a metaphor of sweetness, the olive tree (O. europaea), symbol of mercy, and even clover (Trifolium spp.), a direct recall of the dogma Torino, April 1st - 2 nd, 2004 13 of trinity. In the Arab garden, water represented the main element of its composition, as it was present in fountains, pools and canals. Among the trees, above all the cypresses (C. sempervirens) were grown in large numbers, as they were mentioned in the Koran as symbols of eternity and female beauty. Among the most beautiful creations of Arab gardens, there are the Hispano-Arabic ones of Alhambra in Granada. Generalife and Alhambra are connected by a very valuable avenue of cypresses.

4. The tree in Renaissance, Baroque, and English gardens. In order to fully understand the different elements characterizing the garden of the Renaissance and, consequently, the peculiar use of trees in the architectonic design, a great importance is held by the work entitled Hypnerotomachia Poliphili, by the Dominican Francesco Colonna (Tagliolini, 1991). It describes the love dream of Polyphilus and Polia, transported to the island of Citera. The arrangement of the island and the setting of the plants, strictly managed by perfect harmonical and geometrical rules and relations, constitute the example of the garden during Humanism. The amphitheatre of Venus, placed in the middle of the island astonishes Polyphilus, since on the top of the steps, instead of a colonnade, like in the classical theatre, there are “trees geometrized” by the topiary art and cypresses that create interlaced arches of a vague islamic taste. The perfection of Renaissance gardens and their strong character of permanence derived from a recurring use of evergreen trees and shrubs, such as cypresses, holm oaks, pines, boxes, and citrus trees grown mostly in vase with an ornamental aim. A great fame was acquired by the “Garden of Hesperides” where the golden pomes and the fruits bestowing eternal youth and immortality were kept. A contribution to the cultivation of new tree and shrub species arrived during the XVIth century from the development of botanical sciences that led to the birth of tree and shrub collections inside botanical gardens, among which the Garden of Pisa, founded in 1543, and that of Padua and Florence created in 1545 and 1550, respectively. The studies of agronomy permitted to improve new short growth habits for fruit trees, such as apple, pear and apricot trees (Pozzana, 1990). A precious witness of the fashion prevailing at that time to prune the fruit trees in a dwarf shape is contained in the work by the scholar Agostino del Riccio entitled “Del giardino di un Re”: “Now I have in front the garden of dwarf fruit trees, and one may say unmistakably that it is the pleasure of the ladies and their young daughters, who often go into a small garden with dwarf trees for their retreat and amusement, and they enjoy themselves indeed, especially when the small fruit trees are full of their pomes of different kinds, and sometimes with great taste they take them with their soft hands white like snow and pleasantly offer one to the other. None the less pleasure has the King, when also he enters such a garden for his recreation and walk. But in order to make these dwarf fruit trees be more desired by everyone and to enable them to make them, I will describe them lovingly and nobody will overcome me, unless with a good description in excellent style”. Also during the XVIIth century the scientific literature on botanical themes acquired a remarkable importance thanks to several Authors who gave a precious contribution to the knowledge of tree species, as in the case of the scholar Francesco Pona. The XVIIth century garden did not abandon the axial composition ruled by geometric and mathematic principles, but it widened, almost assuming the feature of a “park–wood”, joining ideally with the surrounding land also because of the lack of a precise definition of its perimeter. The great season of the Baroque garden had its major bloom in France after the first half of the XVIIth century. Parterres, orchard theatres, plants reduced to geometrical shapes, and large arboreous masses, with an evocative chromatic effect, composed the typical scenery of the French garden (Mosser and Teyssot, 1990). Compared with the Italian one, there was a greater presence of woods and thickets, made of medium and tall trees, with principal and secondary avenues having a simple or double set of planting. Plant architecture achieved, in the design of the XVIIIth century garden, a kind of micro-urbanistic complex, characterized by a dedalus of walks and spaces, next to wide walls of green obtained with yews, cypresses and laurels (Vercelloni, 1990). Besides such evergreen species, typical of the topiary tradition, the French garden employed also a considerable variety of wide canopy deciduous trees, such as hornbeams (Carpinus betulus), elms (Ulmus campestris), beeches (Fagus sylvatica), maples (Acer campestre), lindens (Tilia cordata), plane trees (Platanus x acerifolia) and horse chestnut trees (Aesculus hippocastanum). The palisades were created mostly with beeches and maples, while the thickets were made mainly by oaks (Q. robur), beeches and lindens. Box remained the shrub species preferred for the parterres. During the XVIIIth century, the transition took place from the garden of strictness and discipline of geometrical shapes, pertaining to the classical typology, to more various and 14 International Congress on The Trees of History free settings, that led to the birth of the landscape garden. The trend towards an always more romantic and open expansion of the natural element reached its highest expression in the work of two famous landscapists, Lancelot Brown (1715-1783) and Humphrey Repton (1752-1818). Compared with the rigid planning of arbored avenues and of symmetry axes and with the neat definition of the garden limits, the use of tree and shrub species in more disengaged shapes and groupings was promoted, as well as meandering and irregular walks and the abolition of the garden margin with the aim of a total integration of it with the surrounding landscape. In Italy, at the beginning of the XIXth century, Count Ercole Silva, an expert botanist, revisited the Italian tradition according to the general lines of the English school and published his renowned treatise “Dell’arte dei giardini inglesi”: a work that influenced considerably Italian designers during the whole century. In the course of the XIXth century the interest towards exotic species grew remarkably; many of them were trees, that enriched European and English gardens, in particular, with shapes and colours, thanks to the collecting work in all explored continents by the famous “plant hunters”, who were active above all in the United Kingdom.

5. The tree in town avenues and parks After the appearance of new requests linked to the phenomenon of urban expansion during the XIXth century, the concept of urban green established itself gradually. In the Viennese reality, thanks to the demolishment of the walls, the rings could be built: arbored avenues that could recreate the continuity between the historical centre and the town in expansion. Also the city of Lucca, following the cultural models of the time, effected the transformation of town walls from a defensive purpose to a place of walks with the vast realization of arbored avenues. In France, thanks to Napoleon IIIrd, a broad establishment of parks and green public areas in the towns had begun. In Paris, in particular, through the demolition of the historical city, the great boulevards were created: arbored avenues able to connect the greatest celebrative points of the city, planned for walking. They were composed of two rows of trees, mostly plane trees (Platanus x acerifolia), next to a zone for pedestrians in the middle (with kiosks and areas for music) and the route for carriages. The realization of great parks received, furthermore, a meaningful impetus from beyond the ocean, the most famous example of which is represented by Central Park in New York designed by Frederick Law Olmsted, following the principle of “naturalization” of the city, thanks to broad plantings of trees, aiming at a recreating a kind of urban wood. Such a project criterion, conceived for the urban green, assumed the dignity of a real scientific discipline in Anglosaxon countries, known as urban forestry, so to indicate that some green areas can be proposed like oases of rurality inside urban habitats.

6. The tree in Piedmontese parks In Piedmont the most important realizations until the middle of the XIXth century were represented by the gardens of the royal palaces, followed by far, by size and care, by those pertaining to villas and palaces of the nobility, influenced by court gardens and often made by the same creators. The long season of the garden in Piedmont found an important reference point in the two famous figures of André Le Nôtre and Michel Benard. Le Nôtre, the celebrated designer of Vaux-le-Vicomte, Versailles, and Chantilly, was called in 1669 and then in 1697 to give a new shape to the Savoyard gardens. The first plan, designed after a visit to the site, was required by Savoia Carignano for the park of the castle of Racconigi (Roggero Bardelli et al., 1990). The project drawn by Le Nôtre was characterized by a green setting according to geometric modules in which, on a slightly degrading plain around the castle, flower beds, grassy parterres, and water pools are displayed. At the end of the median axis of the park, Le Nôtre placed a wide circular basin and behind it a continuous row of trees, so to underline an arrangement of the space to infinity. Still today several of the entrances of Piedmontese noble villas are characterized by the presence of great shady alleys of poplars (P. nigra L.), elms or hornbeams, creating high green side walls (Accati and Devecchi, 1996). In the middle of the XVIIIth century the French taste had settled down and Charles Emanuel IIIrd entrusted Michel Benard with the management of the crown’s gardens; he was immediately engaged with the realization of the park of Stupinigi, inside the perimeter already defined by Juvarra. The great axis of the entrance, as a major axis, with a strong value in the design of the territory, permitted to join firmly the Palace to Turin. A great importance was, In particular, the use of Lombardy poplars (Populus nigra var. Italica) was of great importance to underline the design on the land thanks to the roads around the Palace complex. A precious testimony of this is provided by the drawing by Ludovico Bo “Pianta Torino, April 1st - 2 nd, 2004 15 della fabbrica da costruersi in contorno delle albere pine [ ] “ of 1779 (Mondini et al., 2003).The diffusion of the landscaping style in Piedmont was due to Giacomo Pregliasco, a scene painter and urbanist who started the first transformations of Racconigi since 1787, with interesting insertions in a picturesque style. The complete transformations according to the romantic taste of the age was accomplished by the famous German landscapist Xavier Kurten, the author of the renewal of taste in the great number of Piedmontese gardens of the first half of the XIXth century (Devecchi, 1999). Kurten’s work had as main points the “isolated tree”, shrub masses and thickets, groups of trees in circle, the lake with irregular sides and a small island, the big lawn, the small hill, and sometimes a small temple. In his several gardens the perspectives can be easily identified and represent the fundamental elements of the theory of the landscape garden and of the picturesque garden fashionable at the beginning of 1800 in Italy and in Europe. At Racconigi, thanks to Kurten’s work, the park received a remarkable enrichment of vegetation, also of trees, so to comprehend many specimens of plane trees, maples, horse chestnut trees, birches, hornbeams, next to elms of the Caucasus, Judas tree, liriodendron, etc. The perspective of arbored avenues and long extents of lawns was a common feature also in Kurten’s projects for the gardens of the numerous Piedmontese noble residences, such as those of San Martino Alfieri (Accati and Devecchi,1994; Accati et al., 1999), Sambuy, Monticello, Pralormo, Santena, Villa Il Torrione, Sommariva Perno, Sansalvà, Castagneto Po (Salina Camerana,1994). At Pralormo, in particular, he took the starting point from the natural scenery of the Alpine chain to propose wise cuts between the trees so to enjoy some preferential views during the walks in the park. The ideal route among the most representative figures who worked in Piedmont cannot exclude the most renowned Italian landscapist of the past century: Pietro Porcinai (1910- 1986). The modernity of Porcinai’s project solutions had a point of force in the attention towards themes of ecology, in the research of a privileged relation with nature, through a constant use of vegetation, but also of natural materials, such as wood, stone, and water to mask the artificiality of architectonic manufacts. The simple and linear design of Porcinai’s gardens found a cue also in the choice of the plant species with a preference for evergreens, such as olive trees O. europaea, cypresses (C. sempervirens) and holm oaks (Quercus ilex). Rhus typhina was a beloved species much used by Porcinai, who exploited the sculptorial and sinuous aspect of its trunk and the particular projection of the canopy that always hides possible constructive elements. In a writing by Porcinai of the ‘50s, starting from correct considerations of a phytosociological kind, he confirmed the concept of harmonic exaltation of shapes and colours of the trees: “It has been discovered that when the plants live together in full associative harmony (botanical harmony) also their habitus and their shape express a harmonic perfection: and such a harmony involves of course also their colour. The most perfect chromatic relations are attained, therefore, with plants that are botanically in harmony”. Porcinai understood the importance to propose gardens, not only as places of aesthetical enjoyment of nature, but as realities where to prove the pleasure of the knowledge of plants and the meaning of the different agronomic practices. Interesting examples to this regard are the “orchards” rich of decorative elements and full of a thousand year old agronomic culture, that were proposed on several occasions by Porcinai, such as Villa Maggia on the hills of Turin. The fruition of gardens was encouraged by Porcinai also thanks to decoration elements, such as a pool, a gazebo, a barbecue, and tennis and bowls courts, included tactfully in the garden’s structure, often screened with hedges of cypresses C. sempervirens, hollies Ilex aquifolium, laurels L. nobilis, oleasters Elaeagnus pungens, hawthorns Crataegus spp., etc., and groups of shrubs, among which, for instance, butterbushes Pittosporum tobira, and boxes B. sempervirens (Accati e Devecchi, 2000). A further remarkable example is represented by the garden of Cà Gianin at Trivero in the province of Biella, that assumed, according to Porcinai’s and the owner’s idea, the meaning of a botanical collection, where interesting tree species are required, having pleasant shapes, colours and seasonality of blossomings. For example, besides the specimens of local or naturalized species of that area, such as beech, sweet chestnut, and birch, a broad use of evergreen species was made, such as Chamecyparis lawsoniana, together with different species, sometimes poorly known, of the genera Picea, Abies, Juniperus, and Thuja. These were planted with a great number of shrubs, above all acidophilous species, such as azaleas, rhododendrons, Pieris, and hydrangeas, that Porcinai requested expressly, probably after having seen them in full vigour in the Burcina Park.

7. Conclusions Since ancient times the tree has held multiple meanings, also ritual and religious ones. Its presence in a garden has always represented an element of capital importance for the 16 International Congress on The Trees of History arrangement of a green area design, even if having diverse shapes and purposes. Therefore, both plant architectures and monumental trees of a park and a garden, as they are in the landscape, must be considered a precious historical and cultural heritage. So an always greater attention and sensibilization of people is more and more needed as far as the importance of safeguarding trees and defining correct management terms are concerned, above all referring to the specimens of monumental interest, with the aim to prevent the loss of a patrimony of exceptional value and not only naturalistic value.

References AA.VV. (1990) – Gli alberi monumentali d’Italia. Edizioni Abete. Roma, 303 pagg. Accati E., Bordone R., Devecchi M. (1999) – Il giardino storico nell’Astigiano e nel Monferrato. Libro, Amministrazione Provinciale di Asti, 230 pagg. Accati E., Devecchi M. (1994) - Alcuni giardini storici del Piemonte centro-meridionale: aspetti vegetazionali e problematiche legate al restauro. Annali Accademia di Agricoltura di Torino, Vol.CXXXVI, 107-123. Accati E., Devecchi M. (1996) - Evoluzione dei criteri di scelta delle specie vegetali nel giardino storico piemontese dal XVI al XIX secolo. Atti del Convegno “Vegetazione e giardino storico”, Ace International, pagg. 39 – 55 Accati E., Devecchi M. (2000) - ll significato e l’uso della vegetazione nel giardino di Porcinai. Atti del Convegno “La continuità e contiguità floristica e paesaggistica nella progettazione dei giardini”. Grugliasco, 25 maggio, 2000, pagg. 14 – 20. Devecchi M. (1999) – Il giardino storico nel Cuneese. Un patrimonio sconosciuto di arte e di cultura. Provincia di Cuneo Ed., 145 pagg. Fariello F. (1967) – Architettura dei Giardini. Edizioni L’Ateneo, Roma, 230 pag. Grimal P. (1990) - I giardini di Roma antica. Garzanti Ed., Milano, 518 pagg. Mosser M. - Teyssot G. (1990) - L’architettura dei giardini d’Occidente. Dal Rinascimento al Novecento, Electa, Milano. Mondini G., Defabiani V., Re L., Nicolotti G., Odone P. (2003) – Studio di fattibilità per la ristrutturazione delle alberate circostanti la Palazzina di caccia di Stupinigi. Atti del Convegno “Giardini storici. metodologie per la conoscenza, strumenti operativi per la conservazione e il restauro”, a cura di M. Devecchi e F. Mazzino Roma, Consiglio Nazionale delle Ricerche, 6-7 dicembre 2000, 154 pagg. Pozzana M. C. (1990) – Il giardino dei frutti. Frutteti, orti, pomari nel giardino e nel paesaggio toscano. Ponte alle grazie Ed., Firenze, 205 pagg. Roggero Bardelli C., Vinardi M. G., Defabiani V. (1990) – Ville Sabaude. Rusconi, Milano, 529 pagg. Salina Camerana A. (1994) - Xavier Kurten: direttore del parco e giardini di Racconigi dal 1820. Atti del Convegno “I giardini del “Principe”, Racconigi,Ministero per i Beni culturali e Ambientali, 705- 713. Tagliolini A. (1991) – Storia del giardino italiano. Gli artisti, l’invenzione, le forme dall’antichità al XIX secolo. La casa Usher, Firenze, 407 pagg. Vercelloni V. (1990) – Atlante storico dell’idea del giardino europeo. Jaca Book, Milano, 207 pagg.

Fig. 1 – An interesting example of the use of trees for creating avenues orienting the views on the most valuable architectonic elements of the garden [Sans Souci Palace – Potsdam] Torino, April 1st - 2 nd, 2004 17

2a 2b 2c 2c

Fig.2 - The use of garden trees in an architectonic shape constitutes an element of great value and recurrent interest in the history of garden art [(2a) SchÖnbrunn Castle - Vienna; (2b) Het Loo Castle – Apeldoorn; (2c) Sans Souci Palace – Potsdam; (2d) Hidcote Manor garden – Gloucestershire]

Fig. 3 – View of a XIXth century print depicting a monumental oak in the park of the Castle of Villastellone, the monumentality of which represented at that time one of the most important attractions of the park

4a 4b Fig. 4 – Trees represent a precious opportunity of putting colours inside a park and a garden, coming from the foliage and, even if more transient, from the blooming [(4a) Prunus pissardii; (4b) Liquidambar stiracyflua]

5a 5b Fig. 5 – The very wide range of shapes and architectures of tree canopies has always been exploited by park and garden designers to evoke different and particular sensations and moods in the observer [(5a) Fagus sylvatica cv ‘Pendula’; (5b) Salix babylonica] 18 International Congress on The Trees of History

THE TREES OF THE BOTANICAL GARDEN OF PADUA UNIVERSITY P. Giulini National Committee for the Historical Garden of the Ministry of Arts and Cultural Property

Introduction The Botanical Garden of Padua (till 1591 was called Hortus Medicinalis) can boast of being the most ancient university botanical garden in the world. It is still in the same place and has the same functions: didactic, of research and of acclimatization of the plants, the latter ordered by the University, just for the commercial advantages which the Republic could derive from the botanical knowledge guaranteed by the garden. To understand the importance of its foundation, preceded chronologically only by Matteo Selvatico’s medicinal garden of the Medical School of Salerno (Giulini, 1992) and by the one of Pisa, we need to immerse ourselves in medieval knowledge when the Church catechized that just God, during the creation, had granted to natural matters the capacities of treating the body diseases, induced by those of the soul: sins. As a consequence of the Confession, therefore, the sinner’s body was healed thanks to the medicinal herbs received from the priest and had, only then, the certainty of having been absolved even in Heaven from the sins committed. From the threshold of the second millennium the treatment of the body and that of the soul were progressively separated. The Padua School gravitated under the strong and attentive leadership of the Venetian Republic and under the flag of Saint Mark, while the power of the Church was definitely limited. As a result the Scholars, only in a very small part Venetians, streamed into the Padua Athenaeum especially from Central Europe and from the Balkans where for many years that contention the Church called “heresy”, and elsewhere was called “Reformation”, had been spreading more intensely. Next to the “Tacuina sanitatis” from the end of the fourteenth century the herbarium manuscripts made by the amanuensis became more and more frequent as did the treatises of the preparation of medicinal herbs not only in Latin after the invention of the printing movable types. The same iconography had a strong evolution leaving more and more the fantastic and superstitious aspects of the plants to look for, instead, the real and salient details, to promote their identification. Thus, the time was ripe to deal with the teaching of the simples (Lectura simplicium), that is medicaments of natural origin (prevalently vegetals) and so called because from the union of the properties of each one, the compound was extracted. Padua had its first professorship in 1533 with Francesco Bonafede from Padua. He gave his lessons “ex cathedra” in Latin, so all the Scholars understood, despite the different languages of provenance. However he realized how difficult it was to be able to understand each other about the plants because already in Latin it was difficult to identify every species with a unique European name and, above all, know what it interfered in the absence of a sample. Therefore he sent a request to the Venetian Republic on behalf of the Professors and Scholars to grant permission to create a “Horto Medicinale” near which lessons of “Ostensio simplicium” could be held, taking the Scholars directly to the heart of the subject. After a three-year wait the government of the Venetian Republic adopted the request on 29th July 1545. By 1546 the Garden was ready for its activity, rich in vegetals that in those times according to tradition, had healing powers. Science, however, was already ready for the interpretation, the verification and discussion of the ancient Authors’ authority. The space destined to the garden was loaded with history and traditions both Roman and monastic; just outside the medieval ring of walls, it was for some years surrounded in the bastioned ring of walls. Its creation was charged to the builder Andrea Moroni from Bergamo, who in those times was completing the most important public and religious buildings of the Renaissance town. The project, said to be conceived even before July 1545 by Daniele Barbaro and Pietro from Noale (Guazzo, 1546), was a “summa” of architectonic perfection in the spirit of the “Hortus conclusus” of the medieval tradition and whose size depended only on the available shape and space. The collaboration between the rising Garden and the adjacent Benedictine Monastery, former owner of the land, was at the beginning so strong that the Head typesetter of Saint Giustina was free with his advice and information.

The ligneous plants Recently studies have been carried out on some drawings dating back to the decades following the foundation (Terwen-Dionisius, 1994); in them the names of the plants are Torino, April 1st - 2 nd, 2004 19 quoted in their first position. Thanks to these lists, brought up to date in the botanical nomenclature by Andrea Ubrizsy Savoia (1995), we can assert for sure that, already some years after the foundation, numerous shrubby and arboreal plants, nowadays considered autochthonous, but prevalently coming from areas commercially influenced by the Venetian Republic, had been placed inside the Hortus conclusus. Among these: the silver fire (Abies alba Mill.), the Italian cypress (Cupressus sempervirens L.), the maritime pine (P. pinaster Ait.), the savin and prickly juniper (Juniperus Sabina L., end J. oxycedrus L.), the true laurel (Laurus nobilis L.), the mulberry (more probably Morus alba L.), some oleanders (Nerium oleander L.), the cork oak (Quercus suber L.), the wild service tree [Sorbus torminalis(L.) Crantz], the common spindle tree (Euonymus europaeus L.), the bladdernut (Staphylea pinnata L.), the white poplar (Populus alba L.), the golden chain (Laburnum anagyroides Med.), the lote tree (Celtis australis L.), the chinaberry (Melia azedarch L.), the date plam (Diospyros lutus L.), and several fruit-bearing trees as pear and plam trees (Prunus L. sp.pl.). Few plants are not mentioned and many others, even exotic, are added in the list of those cultivated in 1591 (Cortuso), list commented and identified according to the present nomenclature by Elsa M. Cappelletti(1995). For instance, among the arboreous trees there are planted out numerous conifers [Juniperus communis L., Picea abies (L.) Karst., Larix decidua Mill., Taxus baccata L., Pinus pinea L.), the oak-trees (Quercus ilex L., Q. robur L., Q. macrolepis Kotschy, Q. coccifera L., Q. petraea (Matuschka) Liebl.], other poplar-trees (Populus nigra L., P. tremula L.), the ash-trees (Fraxinus ornus L., F. excelsior L.), the maple-trees (Acer platanoides L., A. campestre L.), the European field elm (Ulmus carpinifolia Rupp. ex Suckow.) and other fruit-bearing trees enrich the list. To the two lists, mentioned as the most ancient, reporting the trees planted in the Hortus cinctus, successively 13 more followed up to 1842. From that date until 1938, there followed other 45 indices seminum (Gola, 1947) and later 21 more from 1947 to 2004 (Botanical Garden’s Library Archives). These catalogues are the list of the species whose seeds are proposed for exchange with other botanical Institutions. However the indices don’t represent the list of all the trees growing in the Garden at a certain date, but only of those offered for seeds exchange. For more than ten years the indices also have included the seeds of dying out species, not only those picked up in the Garden but also in the surrounding areas. After four centuries no trace remains of the above-mentioned shrubby and arboreal plants. However we can’t leave out two worth mentioning plants which date back to that time. Northward, outside, but close to the boundary wall, there lived till 1984 a white-flowered, well grown-up chaste-tree (Vitex agnus-castus L.) with large foliage and vast bloom. After 1975, unfortunately, a fungus infection to the conductive vessels little by little made it die. The documentation which names it in 1550, the anomalous position in which it lived and the suspected aphrodisiac properties marking this species make many scholars conclude that this tree pre-existed the Garden’s foundation and it could possibly be a trait-d’union with the medicinal Benedictine Garden. The rests of this chaste-tree are still preserved in stores, expecting to be shown soon. Nowadays in the Garden, the oldest living tree is a dwarf palm or European palm-tree [Chamaerops humilis L. var. arborescens (Pers.) Steud.] which dates back to 1585. This palm, already bicentenary, was seen and studied by Johan Wolfgang von Goethe, during his journey in Italy on 27th September 1786. The hypotheses obtained from this research were published later in 1790 in Die Pflanzen Methamorphose thanks to which our palm-tree was celebrated through the following centuries by the visit of thousands of Germans, as if going on a cultural pilgrimage, so much so that it was no longer the dwarf palm tree of the Botanic Garden but Goethe’s palm tree. For centuries, in winter, it was protected by the movable store wooden structures in order to avoid that this specimen, which had much grown and become historical not only because of its age, might succumb to an exceptionally severe winter. In 1874 it was protected by a larch greenhouse built ad hoc and replaced between 1935 and 1936 by another structure of reinforced concrete. As the palm tree has always lived in a a favourable climate, it is still very luxuriant and is provided with many stems, some of which are eight metres high. The tree doesn’t suffer from any pathology. Relatively nearer to us in order of time, since 1680, outside the round enclosure, there has been living a western huge trunked largely hollowed plane tree (Platanus orientalis L.). On the basis of a XIX century water-colour we learn that, at the date of the picture, the trunk was still healthy and solid but had a large scar crossing it through from top to bottom. The wound cause can be traced back to a thunder-bolt, however a rot [Ganoderma applanatum (Fries ex Persoon) Pat.] hollowed the trunk out within a century. In spite of the impressive cavity, the tree, regularly pruned in order to avoid an excessive growth of its foliage and to grant a better stability, is living quite well 20 International Congress on The Trees of History and, thanks to the treatments dating back to about 40 years of “carbolineum” diluted in petroleum paintings, its infection has receded so much as not to have produced any more fruitful bodies for almost 15 years. Two more over centenarian trees live inside the enclosure. A male maidenhair tree (Ginkgo biloba L.) planted out near the corner of the fourth part North west (Spaldo as it was called in old times) now called “Quarto del Ginkgo” dates back to 1750. It is therefore the oldest specimen of this species still living in Europe. Half century ago in one of its low branches was grafted a female branch which every year produces quite a lot of fertile semen. This fragile wooded living fossil has lost for over one hundred years its straight bole owing to the crashes caused by violent rain storms, yet its scars are quite healthy with a large healed callus. A bull bay (Magnolia grandiflora L.) is living near the centre of the fourth part in the South west side. Some sources date it back to 1756 while others to 1786. Anyhow we are dealing with one of the oldest plants in Europe which, owing to its position, has never been able to develop itself properly and has shown recently important foliage thinness and a less flower blooming. The radical apparatus is superficial because the soil is very heavy and asphyctic. This very situation must be the main cause of its limited growth. It is one of the first plants in the Garden infected by the honey fungus (Armillaria sp.) two decades ago at least. Various areas of ceased growth and of consequent decortications such as, on the other hand, mushroom clusters are present, late in Summer, on the infected roots. On the margins of decorticated areas the reaction callus is always very limited, in spite of that, the whole plant is still alive. Up to now no drastic intervention has been made partly because it is justly believed that inside the Hortus conclusus arboreal species are not to be planted out, partly because to cure this plant all the arrangement of the Fourth part which is entitled to this magnolia, should be entirely upset, and thirdly because the intervention has seemed to us to be in extremis. Outside the surrounding wall a very tall black pine (Pinus nigra Arn.) dating back to 1772 is still perfectly luxuriant. It is the only plant still living which surely was part of the Arboretum, conceived, carried out and corrected by Giovanni Marsili (1727- 1795, Prefect of the Garden from 1760 to 1794). This particular Arboretum, few years later, was largely imitated by many other Botanic Gardens. The certainty about the age of the plant doesn’t come only from XVIII and XIX cartographic documents but also from a check through a dendrochronological study (Zennaro, 1996-97) made on numerous healthy subjects present in the site. Again in the Arboretum context there lives a holm hoak (Quercus ilex L.) dating back to the first lay-out. Unfortunately an old devastating caries has transformed it into an empty trunk united to the ground through stilts which prevents us from ascertaining its age. As to Marsili’s plan it had a short life, both because the Holm hoak was planted a order of a fixed plantation and also owing to a terrific hail storm on August 26th, 1834 which destroyed the whole Garden and its greenhouses [de Visiani (in Paganelli, 1995) relates that Bonato, at that time already very old, almost died of broken heart]. Only few more competitive and strong subjects survived and little by little they were substituted by other Prefects who come later and who planted out new trees according to the growth size of any single species following Marsili’s specific indications: especially Giuseppe Antonio Bonato 1753-1836, Prefect between 1794 and 1835 and Roberto de Visiani 1800-1878, Prefect from 1836 to 1878. Just from the beginning of the XXth century the Arboretum around the walled Garden has extended and renewed itself, but above all, it has filled with new arboreous trees whose seeds came from the Far East and America. Some deciduous plants are important for the date of their arrival: plants such as Magnolia L., various walnut-trees as Juglans L. & Carya Nutt, two bull bays at the entrance of the Garden which date back to 1801 and have always exercised a great effect on visitors. Even the landscape of this vast area changes according to the fashion of the English Garden with no longer rectilinear tracks and with the raising at the South east edge of the Garden of a panoramic hill overlooking the surrounding gardens, kitchen-gardens and the orchards. In 1828, close to the panoramic hill, the first deadar [Cedrus deodara (D. Don) G. Don] was planted from seed in Europe. This date, reported in literature, is the true one attesting the arrival of this species in Europe (Maniero, 2000). On the western Garden edge, along the bank of Alicorno canal, near the border, a row of bald cypress (Taxodium distichum (L.) Rich.) was planted. They are still living but have been brutally cut on two following occasions owing to wrong interventions of the neighbouring Jesuits (from dendrochronological researches all the trees present very deep hart rots). In the second half of the nineteenth century, also some species of Japanese cedar (Criptomeria japonica D. Don) and California redwood [Sequoia sempervirens (D.Don) Endl.] were planted out. Certainly they hadn’t a good growth owing to the soil nature and climate, nevertheless this plant is still alive and thriving notwithstanding its stability problems. Torino, April 1st - 2 nd, 2004 21

The preservation of historical species The preservation of species of particularly historical importance create many problems of maintenance, especially for large plants in such a narrow space (the Garden of Padua has had till now an area of little more than 2,2 hectares). Moreover the urban, more and more polluted climate and the building “siege” all around cause serious problems during the summer down-pours. The exemplars bent by the wind or by crashes of fallen trees are steadily anchored to close plants or plinths on the ground. A similar thing executed on some branches of large size. The anchoraging grants not only an elastic support to the protected subject but also avoids that a sudden crash may cause damages to the people working there (technicians) and visitors. Therefore besides curative pruning on crashes and disinfection of wounds, necessary to grant the health of our plants, we must also operate on contraction pruning carried out with the utmost care and attention so as to lengthen these specimens’ lives, which are often in a natural phase of aging but above all in an ecologically anomalous environment as to their original climate. Tree climbing modern technique helps us greatly especially in our space where the extensible jibbed cranes have an overwhelming impact on the ground owing to their weight and the scarce manoeuvrability of the cab among the foliage. Dendrosurgery is rarely used because constant checks allow us to-day to intervene promptly on the saprophyte attacks. In the past the use of “carbolineum” solved many problems, yet the results have not always been positive in fact we have lost quite a lot of specimens, exotic for the most part, owing to a basal stem rot (the empty spaces are not noticed by visitors, but for those who have always worked there and lived in and for the Garden for a long time, they are and will always be open wounds). Over ten years ago the news that a residential building, bordering the Garden, was being built against any legal orders and breaking the low, spread far and wide throughout the world. For four months the surface water-bearing stratum was dried up, upsetting, in so doing, the whole site where an underground garage 10.000 m2 large was built. The opinions on the real responsibility of this crime for the damages caused to the Garden are still much debated and perhaps almost impossible to demonstrate owing to timely interventions. I myself am a strenuous supporter of the intransigent wing and believe that the root rot which was modestly present in the past, is now the consequence to the present hydro-derangement. The University Committee promptly built an irrigation plant-system at their own expense. However the going up and going down of the water are two physiologic situations quite different if referred to plants with a physiologic precarious balance. Since 1996 University Botanic Pathologists have planned a research with a view to limiting the root rot diseases by removing less valuable vegetable subjects, especially those more struck down by this illness and taking away the most infected soil and treating the rest with fumigations. The two bull bays which stand at the entrance have been firmly anchorated by strong supports. Their main roots have been laid bare, the soil has been substituted with expended clay and Trichoderma sp. has been inoculated as a powerful antagonistic to Armillaria sp. drug (Zuccoli Bergoni 2002-2003). Conclusions From what has been said the importance of historic tree conservation is evident. Historic trees are the witnesses of man’s life and of his landscape. Saving them depends almost always on few expert’s responsibility. Destroying them has always depended on many people’s interests and profits. For a Botanic Garden the choice lies on the engagement to protect all subjects to postpone their death which is unavoidable anyhow. As to Historic Gardens, besides fighting in favour of their preservation, we must accept the conscious choice of a renewing life because priority utterly concerns the vegetable world as a whole. Bibliographyy Cappelletti E. M., 1995 – Le collezioni viventi nell’Orto botanico ai tempi del Cortuso. In “L’Orto botanico di Padova 1545-1995" a cura di A. Minelli. Marsilio. Venezia. pp. 197-242. Cortuso G. A., 1591 – L’Horto dei semplici di Padova, ove si vede . G. Porro. Venezia. Giulini P., 1992 – Quale futuro per il ritrovato Orto botanico della Scuola Medica Salernitana, primo nella storia europea. In “Pensare il Giardino” a cura di P. Capone, P. Lanzara, M. Venturi Ferriolo. Guerini, Milano. pp. 185-189. 22 International Congress on The Trees of History

Gola G., 1947 – L’Orto Botanico. Quattro secoli di attività (1545-1945). Liviana. Padova. Guazzo M., 1546 –Historie di tutti i fatti degni di memoria nel mondo successi dall’anno MDXXIIII sino a questo presente con molte cose novamente giunte Venezia. Paganelli A., 1995 – Giuseppe Antonio Bonato. In “L’Orto botanico di Padova 1545-1995" a cura di A. Minelli. Marsilio. Venezia. pp. 97-107. Terwen-Dionisius E. M., 1994 – Date and design of the Botanical Garden of Padua. Journ. of Garden History XIV: 213-235. Ubrizsy Savoia A., 1995 – L’Orto botanico di Padova all’epoca del Guilandino. L’Orto botanico di Padova 1545-1995 a cura di A. Minelli. Marsilio. Venezia. pp. 173-195. Zennaro A., 1996-97 – Indagine dendrocronologica su alberi viventi presso l’Orto botanico di Padova. Tesi di Laurea in Scienze Naturali, relatore P. Giulini. Università di Padova. Torino, April 1st - 2 nd, 2004 23

AGING PROCESSES IN TREES AND THEIR RELATIONSHIPS WITH DECAY FUNGI D. Lonsdale 33 Kings Road, Alton, Hampshire UK formerly of Forest Research - Alice Holt Research Station

Abstract The development of physiological dysfunction within the central wood of old trees is a major feature of the aging process, together with a tendency to become unable to maintain a complete outer shell of functional tissues. Species-related differences in the durability of the dysfunctional wood are of key importance in the ability of trees to live to a great age. Due to the differing abilities of various decay fungi to colonise functional and dysfunctional wood and to cause its degradation, the longevity of a particular tree depends partly on the particular fungal species which colonise it.

Introduction The developmental characteristics of a particular species play a major role in determining its aging processes. Most tree species have an indefinite pattern of growth, as they produce new shoots, roots and radial increments of wood and bark throughout their lives. On the other hand, organisms with a definite growth pattern (e.g. coelomate animals) usually have a far more limited potential for growth after reaching maturity. Thereafter, their growth usually involves only the repair and replacement of worn out or damaged cells, although some species may gradually increase in size throughout life. The repair of existing body parts cannot indefinitely maintain full function, so that aging and death eventually occur. In contrast, the ability of most tree species to form a new ‘living outer shell’ in each growing season could in theory be regarded as allowing some potential for immortality. In practice, however, a tree tends to have a life-span which, although less pre-determined than that of a human being, falls within a range typical of its species. Although trees are fundamentally different to organisms with a definite growth pattern, they share some processes of aging with them. These involve the aging of cells that normally survive for a number of growing seasons, and perhaps also the accumulation of ‘errors’ within the genome of meristematic cells. Despite some indications that such aging may have physiological effects on the newly formed tissue of old trees of some species, there is no reason to believe that it limits their longevity. Instead, the main processes that limit longevity are related to the accumulation of old, dead tissues within the tree. In particular, the older layers of sapwood lose their water-conductivity and their parenchyma cells eventually die. They are then described as being physiologically dysfunctional (or just ‘dysfunctional’ for short) even though they remain structurally functional. The reasons why an increasingly large core of dysfunctional wood tends to limit the lifespan of a tree include the following: 1. the progressive thinning and attenuation of the radial increments of new wood and bark around a core of increasingly large girth; 2. the development of decay within the increasingly large and decay-prone dysfunctional core of the tree, with two possible consequences: (a) the physical break-up of the tree and/or (b) the killing of sapwood and bark by decay fungal species with an ability to overcome the defences of functional tissues; 3. the alteration of the tree’s growing conditions due to its continued growth, including (a) the depletion of mineral nutrients locked up in its wood and (2) alterations in the moisture content and aeration of the soil beneath an increasingly large and dense rootplate. The above three factors will now be considered. Additionally, the maintenance of functional tissue within the main stem will be considered in relation to the retention and growth of branches.

Change in ring width with age During its early life, a tree colonises the space available to it, both above and below ground (Raimbault, 1995), as determined by the environmental conditions and the tree’s inherent physiological characteristics and growth potential. During this formative or ‘exploratory’ phase, the volume of successive radial increments tends to increase, because the crown volume and hence the photosynthetic capacity of the tree is increasing (White, 1998). Eventually, however, the crown approaches its maximum size, at which stage the tree is regarded as having reached maturity. On this basis, White (loc. cit.) recognises three phases in the life of a tree: formative, mature and ‘senescent’, although it should be 24 International Congress on The Trees of History noted that the term senescence is perhaps unsuitable to describe an organism that still has considerable vitality and thus shows re-iterative growth in between episodes dieback (Raimbault 1995). Also, it should be noted that Raimbault (loc. cit.) has recognised a number of intermediate stages, according to changes in the crown architecture. The increase in diameter of the woody cylinder during the mature phase causes the increments of new wood to become progressively narrower. This happens because the crown of a tree reaches a maximum size in maturity and for a long period thereafter tends to produce the same average amount of photosynthate each year, albeit with fluctuations due to weather and defoliation events. The radial increments of new wood and bark therefore have about the same volume in successive growing seasons, but are spread out over an increasing girth (White, 1998). White (loc. cit.) suggested that radial increments can continue to form, despite becoming progressively narrower, until as many as 20 xylem increments make up one centimetre of radial growth; i.e. the average incremental width is 0.5 mm. On the basis of White’s model, a specimen of Quercus robur or Q. petraea, growing under the most optimal conditions available in Britain, could theoretically maintain a complete outer ‘shell’ of new sapwood and bark until beyond the age of 4000 years (Fig. 1), by which time its stem would be almost 8 m in diameter. On the same basis, a specimen within a woodland would reach this stage at about 1100 years of age, when its diameter would be nearly 2 m. Although radial increments could in theory continue to form for centuries or even millennia, it can be postulated that this process will eventually be perturbed because the increments will become so narrow and attenuated as to have insufficient conductive and storage capacity to maintain a full crown. It can further be postulated that a process of negative feedback will then ensue; in other words the dieback of the crown, due to insufficient physiological support from the vascular and storage system, leads to a reduction in the supply of photosynthate to the cambium, which in turn leads to an acceleration in the narrowing of new radial increments; more than would be expected purely because of the geometrical effect of increasing girth. When a tree enters such a state, it shows characteristics (especially episodes of dieback) which are regarded as typical of the declining phase of its life. Loss of continuity in the outer shell of functional tissue Observations of ancient and veteran trees show that discontinuities eventually tend to develop within the outer shell of living sapwood and bark. These usually take the form of dead strips of tissue, subtended by individual branches or roots which have died back or broken. In some cases, such strips may occupy a greater proportion of the tree’s girth than the adjacent living tissue (Fig. 2). It is well known that the death, breakage or severance of branches or roots can lead to the dieback of strips of associated cambium within the main stem, but it is also possible that dieback could be initiated within the cambium, leading to a situation in which a branch or root becomes deprived of a connection with new sapwood and phloem and then declines. Although the exposure of dead tissue at the surface may increase the rate of decay, the restriction of cambial growth to discrete strips around the circumference of the stem may be seen as a survival strategy for a tree that can no longer maintain a complete functional shell of sapwood and bark.

Dysfunction induced by injury A completely intact tree has a covering of bark over its entire woody cylinder and a covering of epidermis or other protective layers over its non-woody extremities. In practice, virtually all trees suffer some degree of injury, which exposes the underlying tissue to an altered environment. In particular, exposed sapwood is often subjected to desiccation and a consequent increase in gas exchange (Boddy and Rayner 1983). In many cases, there is also a direct severance of conductive pathways. These changes lead to a loss of physiological function in the affected tissues, often culminating in the death of tissue within discrete anatomical compartments (Shigo and Marx 1977). In old trees, such changes are of course accompanied by processes of aging which may lead to dysfunction in their own right. (The term ‘veteran tree’ is sometimes used to describe a tree of any age that has survived the vicissitudes of life, irrespective of whether it is ancient or has merely undergone much injury or stress.) In extreme cases, trees can become entirely dysfunctional as a result of severe injury and thus die. This is particularly likely to happen in the case of ancient trees which, have a very narrow and attenuated layer of functional xylem and phloem, overlying a large mass of older dysfunctional wood. It is even more likely to happen if the tree species is one that Torino, April 1st - 2 nd, 2004 25 lacks a durable heartwood, since rapid fungal colonisation of the exposed dysfunctional core can often spread to the overlying sapwood. This will be considered below in relation to the colonisation strategies of different fungi. Even if the entire crown of a tree is removed, this does not immediately cause the death of tree, but it does destroy all conductive function within the entire cross-sectional area of wood in the stem. Also the removal of foliage deprives the tree of its photosynthetic capacity, so that there is a severe drain on carbohydrate reserves and a consequent impairment of active processes in the formation of defensive barriers (Shigo and Marx 1977). Also, there is much observational evidence that sapwood tends to become dysfunctional if becomes isolated from the continuous network of living cytoplasm (the symplast) which normally exists throughout the root and shoot systems. As mentioned above, a tree with large, exposed areas of dysfunctional tissue can survive, provided that its main stem retains functional strips of wood and bark. Such strips represent living channels between the foliage and the tips of the roots and they appear to be of key importance in the survival of ancient trees (Lonsdale 1996). Such trees may need to be managed so as lighten a load of heavy branches that would otherwise fail and cause the break-up these trees. In doing such work, it is recognised that living connections should be protected, which can be achieved by retaining some of the branches. Some past attempts to manage neglected ancient trees in Britain led to excessive wounding and hence to the severance of all the living channels and in many cases death of the trees concerned. The risk of ancient trees dying after major branch breakage or severance appears to be increased by drought stress, leading to severe moisture loss from the exposed wood. Direct heating of the stem, and perhaps also of the ground surface in the rooting zone, due to the removal of shade appears to have a similar effect (E. Green, personal communication). On the other hand, excessive retention of shade can inhibit the development of healthy new shoots. The extent to which shading needs to be reduced or retained depends partly on the tree species concerned; i.e. whether it is shade-tolerant. The local climate, the time of year and the soil conditions are important factors in this respect. If a tree loses most of its crown, its continued survival depends very largely on its ability to form new branches and foliage. It has been observed in Britain that many of the trees that have lived long enough to be considered ancient have, as individuals, a strong tendency to produce epicormic shoots, especially in the case of Quercus robur and Q. petraea (Fig, 3). If a branch breaks or is removed, such shoots can rapidly develop into new branches, thus maintaining physiological function within their associated parts of the main stem. It has also been observed that individual trees of a given species differ in their ability to produce new shoots from dormant buds (Read et al. 1996; Read 2000). Branches that have grown slowly have more nodes per metre and hence more dormant buds. Another observation is that adventitious buds in some species (e.g. Fraxinus excelsior) form more readily along the torn margins of a branch break-out injury than in the vicinity of a saw cut. When new branches grow following injury, they can continue to survive and thus to contribute to the vitality of the tree only if they become independent of the existing tissues before these undergo inevitable dieback and microbial attack. Once the new aerial growth is producing enough photosynthetic material to support both root regeneration and the production of new wood in the main stem of the pollard, the survival of the ‘new tree’ is usually assured. In some cases, trees have survived long enough to produce new growth, but this has subsequently died back (Fig 4), perhaps because it was not linked via channels of new tissue to the root system. Such dieback may be associated with fungal colonisation, as discussed below. In such cases, the entire tree can die very quickly. Sometimes, however, further shoot formation may begin lower down and thus closer to surviving roots. Although a pollarded tree can be killed by total re-cutting of the crown, there are some species, such as Salix spp., Tilia spp. and Taxus baccata that often produce new shoots readily after such treatment. There are others that can also respond well, but that are more likely to survive if at least one or two branches are retained; these include Ilex aquifolium, Carpinus betulus and Fraxinus excelsior. Some species of oak, including Q. robur and Q. petraea, often respond well even if most of the upper foliage-bearing branches are removed.

Dysfunction in the central part of the root system Decay initiated below ground appears to be a common feature of all ancient trees, whether or not they also have decay developing extensively from above-ground wounds. The apparent seat of decay below-ground is often the region immediately under the main stem, where there were once roots that formed early in the life of the tree. It is not entirely clear at which stage such roots typically become dysfunctional, but the presence of decay 26 International Congress on The Trees of History in the stem base is often not externally apparent until the tree is in the post-mature phase of its life. Such decay can occur in younger trees, sometimes when there is a history of root injury or disturbance. Well known examples of fungi that colonise the central rooting zone of trees include the basidiomycetes Armillaria spp., Ganoderma spp, Meripilus giganteus, Phaeolus schweinitzii, Sparassis crispa and the ascomycete Ustulina deusta (Lonsdale 1999; Schwarze et al. 2000a). Extensive decay can also be caused by Inonotus dryadeus and Grifola frondosa , both of which are particularly common on Quercus spp., but these fungi often appear to leave enough of the lateral roots intact to ensure good stability. The significance of sapwood and of old central wood in the survival of ancient trees The high moisture content of functional sapwood usually provides insufficient gas exchange for significant decay to occur. This is a form of passive defence against most decay fungi (Boddy and Rayner, 1983). Even if dysfunction develops in sapwood due to injury or disease, the dysfunctional zone may remain very localised within pre-existing anatomical boundaries, such as vessel endings, or the interfaces between annual increments. The anatomy of the wood is, therefore, an additional passive defence (Shigo and Marx 1977). It is possible for a dysfunctional zone to become larger, due to further drying of the wood, but this is often prevented by an active response of the sapwood, which helps to seal off the damaged tissue. In this response, the cell lumina and inter-cellular spaces become impregnated with substances which are produced by the parenchyma cells. These impregnating materials may include gums, resins and suberin, as well as phenolic compounds which inhibit fungal growth. Also, as pointed out by Shigo and Marx (loc. cit.), the new annual increments which are laid down after the exposure of the sapwood are especially well protected against the spread of dysfunction and decay. The ability of sapwood to respond actively to injury and fungal invasion declines with age because the parenchyma cells have a limited life. In some tree species, such as beech (Fagus sylvatica), the process of cell death occurs gradually over several decades so that the wood becomes less able to respond to fungal invasion if it happens to be exposed by a wound. The same is true of certain other species, such as Aesculus hippocastanum and Fraxinus excelsior, in which the heartwood is distinct from sapwood but lacks the active defence mechanisms of sapwood. In yet other species, such as Quercus robur and Q. petraea, however, the xylem parenchyma is programmed to die after a number of years, so that the sapwood is converted into a distinct heartwood which contains substances that protect it against microbial colonisation and which represents a form of passive defence. Tree species in which the central core of dysfunctional wood is readily colonised by decay fungi tend to live less long than species with a durable heartwood. This difference in average lifespan is probably due in part to the tendency for extensive decay to lead to major mechanical failure, which leads to massive exposure of wood to the atmosphere, an accelerated rate of fungal development and in many cases death of the tree soon afterwards. Such a sequence of events is well recognised in species such as F. sylvatica. If, however, the central wood is a relatively durable heartwood (as in the case of Q. robur, for example), fungal decay is often so slow that major weakening and catastrophic mechanical failure do not occur until a very late stage, perhaps after several centuries have passed. In many such cases failure never occurs, because it becomes less likely as the small-scale failure of individual branches leads to a reduction in the size of the crown. Also, the radial growth of the tree may to some extent keep pace with the development of the decay.

The role of different fungi in the death or survival of ancient trees Species of decay fungi differ considerably in their ability to colonise and to degrade the wood of trees (Rayner and Boddy 1988; Schwarze et al. 2000a). These differences relate to their tolerance to or preference for particular conditions. These conditions include moisture content, gas exchange rate, nitrogen content, and various defensive substances including some that form physical barriers and others that are fungitoxic or fungistatic (Pearce, 1996). The ability of a particular fungus to cope with a particular set of conditions determines its ability to colonise functional sapwood, or dysfunctional wood which may be of high or durability. Sapwood pathogens tend to have a rapid invasion strategy, by which they can colonise sapwood rapidly and extensively, but without causing decay until the wood later dries out partially. At this early stage, they exploit easily assimilated food sources, such as sugars, while colonising the tissues so rapidly that there is not enough time for the active defences of the tree to halt their attack. At least some of these fungi also suppress the active defences of the tree by secreting toxins which damage or kill the xylem parenchyma cells. Torino, April 1st - 2 nd, 2004 27

Such fungi are often known as fresh wound parasites or wound rot fungi, as they are specialised invaders of living sapwood and are usually not adapted to colonise old wounds. The most aggressive fresh wound parasites, such as Chondrostereum purpureum, are not usually associated much with ancient trees, but there are other fungi such as Stereum species and Bjerkandera adusta, which can colonise sapwood rapidly when it has been rendered partially dysfunctional by wounding or disease (Lonsdale and Wainhouse 1987), especially under desiccating conditions. The dead specimen of Carpinus betulus in Fig. 4 was colonised and probably killed by B. adusta. Another fungus that can colonise trees desiccated by sunscorch or fire damage is Schizophyllum commune (Butin 1995). Another strategy by which some decay fungi colonise sapwood is by spreading out from a column of colonisation well established within the central dysfunctional wood of the tree. Such fungi are probably more likely to limit the longevity of trees than those that remain confined to the dysfunctional core. For example, Schwarze and Ferner (2003) have shown that species of Ganoderma differ in their ability to colonise sapwood. They found that G. adspersum was able to penetrate the defensive barrier separating functional from dysfunctional wood. On the other hand, G. applanatum did not have this ability, but had a greater potential to degrade the wood. Within durable heartwood, only fungi with tolerance to the relatively adverse conditions, in particular a high concentration of anti-microbial substances, can cause extensive decay. Such fungi, such as the brown rotter Laetiporus sulphureus, tend to develop slowly, so that ancient trees can often co-exist with them for many decades or even centuries. In this context, one of the most benign decay fungi is probably Fistulina hepatica, which degrades the tannins in heartwood for a long period before starting to degrade the cell walls (Schwarze et al. 2000b). Another important colonisation strategy by certain decay involves a latent or endophytic establishment phase, in which no overt change occurs within the wood (Lonsdale, 1983, 1997). These fungi commonly occur throughout most of the sapwood of a wide range of broadleaved tree species. In some cases, a genetically uniform fungal individual is present within a strip of wood that can be several metres long (Boddy and Rayner 1981). Usually, these fungi enter into an active decay or pathogenic phase only if the host tissues are damaged or altered in some way, especially by desiccation. In ancient trees, fungi such as Vuilleminia comedens and Peniophora quercina (Boddy & Rayner, 1991; 1984) frequently develop in individual branches that have declined in vitality They can play a part in ‘natural pruning’ (Butin and Kowalski 1983), sometimes to the benefit of the tree if its crown would otherwise remain too large to withstand strong winds. Some of these fungi, however, such as Eutypa spinosa (Hendry 1993; Hendry et al. 1998), seem able to kill trees that have been stressed. The type of wood degradation caused by a particular fungal species is another factor in the ability of ancient trees to survive, as some kinds of decay are more likely than others to weaken the wood (Schwarze et al. 1997). The main distinction is between brittle decay and non-brittle decay, but there are many types of decay with intermediate mechanical properties. Brown rot fungi, such as Laetiporus sulphureus, produce a brittle decay because they degrade the rope like cellulose component of the wood, leaving the cement like lignin almost intact. In contrast, fungi that cause a selective white rot degrade the lignin preferentially, so that the wood retains some of its tensile strength, but loses its stiffness. In some extreme cases, species of Ganoderma leave so much of the cellulose unaltered that the wood can be bent like a rope, without breaking. A relatively brittle decay can be produced by other kinds of white rot (simultaneous white rot), in which the cellulose and lignin are degraded at about the same rate. The decay produced by Fomes fomentarius is of this type. Eventually, either a selective or a simultaneous white rot sometimes progresses to the complete destruction of the wood, so that a cavity is formed. A relatively brittle kind of decay can also result from a form of rot in which the fungal hyphae tunnel within the cell walls, degrading the cellulose microfibrils as in a soft rot. This mode of degradation, known mainly in timber, is now known to be induced by a wide range of tree decay fungi, such as Inonotus hispidus, (Schwarze et al. 1995), a species commonly found in old specimens of Fraxinus excelsior, which also cause white rots, and in a few cases brown rots (Schwarze et al. 2000a).

Alteration of the tree’s growing conditions due to its continued growth The idea that trees alter their own growing conditions as they grow larger is perhaps based more on observation and on theoretical assumptions, rather than on rigorous data. As far as soil moisture and aeration are concerned, one observation is that signs of anaerobic conditions, shown by the presence of a bluish colouration, are sometimes found in the soil 28 International Congress on The Trees of History underneath the central zones of the rootplates of uprooted trees. Such colouration underneath rootplates can be expected to occur in waterlogged or compacted soils, but it is sometimes found in light, open-textured soils. It seems possible that, through respiration of roots themselves, or of organisms colonising them, oxygen can become locally depleted. Whether this is a factor in the eventual death of roots directly beneath the stem of a large tree is uncertain. As mentioned above, this pattern of death appears to be important in the development of below-ground decay in ancient trees. Mineral nutrients such as potassium are clearly sequestrated within the wood of a large tree, but it is not clear whether this process commonly results in a deficiency for the tree itself. The decay process releases nutrients and is therefore likely to be of nutritional benefit to the tree. In many cases, a hollow tree develops adventitious roots within its own cavity, so that it can directly re-absorb nutrients that were previously locked up within its dysfunctional core. Conclusions The aging of trees is often compared to that of humans and other animals, and there are indeed some analogies that can be recognised. However, there are fundamental differences due to the manner in which trees can continue to grow and to the microbial exploitation of their accumulated dead tissue. References Boddy, L. & Rayner, A.D.M. (1981). Fungal communities and formation of heartwood wings in attached oak branches undergoing decay. Annals of Botany 47, 271 274. Boddy L. & Rayner A.D.M. (1983). Origins of Decay in Living Deciduous Trees: The Role of Moisture Content and Re Appraisal of the Expanded Concept of Tree Decay. New Phytologist 94, 623 641. Boddy, L. and Rayner A.D.M., (1984). Internal spread of fungi inoculated into attached oak branches. New Phytologist 98, 155-164. Butin, H. (1995). Tree diseases and disorders. (D. Lonsdale, R.G. Strouts., eds.), Oxford University Press, Oxford, UK, 252 pp. Butin, H., and T. Kowalski 1983. Die natürliche Astreinigung und ihre biologischen Voraussetzungen I. Die Pilzflora der Stieleiche (Quercus robur L.). European Journal of Forest Pathology 13, 428 439. Hendry, S.J. (1993). Strip cankering in relation to the ecology of Xylariaceae and Diatrypaceae in beech (Fagus sylvatica L.) PhD Thesis, University of Wales, Cardiff, UK. Hendry, S.J., Lonsdale, D. & Boddy, L. (1998). Strip-cankering of beech (Fagus sylvatica): pathology and distribution of symptomatic trees. New Phytologist 140, 549-565. Lonsdale, D. (1983). Some aspects of the pathology of environmentally stressed trees. International Dendrology Society Yearbook 1982, 90-97. Lonsdale, D. (1996). Pollarding success or failure; some principles to consider. In: Pollard and Veteran Tree Management II, ed. H. Read, City of London Corporation, 100-104. Lonsdale, D. (1997). Das Zersetzungspotential verschiedener holzabbauender Pilze in Bäumen. Proc., Osnabrücker Baumpflegetage, Germany, 2-3 Sept., 1997 XI 12-22. Lonsdale, D. (1999). Principles of tree hazard assessment and management. Research for Amenity Trees No. 7, The Stationery Office, London, 388 pp. Lonsdale, D. & Wainhouse, D. (1987). Beech bark disease. Forestry Commission Bulletin 69, 15 pp. Pearce, R.B. (1996) Antimicrobial defences in the wood of living trees. (Tansley Review No. 87) New Phytologist 132, 203 233. Raimbault, P. (1995). Physiological diagnosis. In: The tree in its various states: diagnosis and architectural training. Proc. Second European Congress of Arboriculture, Versailles, Sept. 1995. Rayner, A.D.M and Boddy, L. (1988). Fungal decomposition of wood; its biology and ecology. Wiley, 587 pp. Read, H. (2000). Veteran Trees: A guide to good management. English Nature, Peterborough UK. Read, H.J., Frater, M. & Turney, I.S. (1996). Pollarding in Burnham Beeches, Bucks.: a historical review and notes on recent work. In: Pollard and veteran tree management, 2nd edn, H.J. Read (ed)., Proc. meeting, Corporation of London, Burnham Beeches, Bucks, March 1991. Schwarze, F.W.M.R. Lonsdale, D. & Fink, S. (1995). Soft rot and multiple T-branching by the basidiomycete Inonotus hispidus in ash and London plane. Mycological Research 99, 813-820. Schwarze, F.W.M.R., Lonsdale D. & Fink, S. (1997). An overview of wood degradation patterns and their implications for tree hazard assessment. Journal of Arboriculture 21, 1-32. Schwarze, F.W.M.R., Engels, J. and Mattheck, C. (2000a). Fungal strategies of wood decay in trees. Springer, 185 pp. Schwarze, F.W.M.R, Baum, S. and Fink, S. (2000b). Dual modes of degradation by Fistulina hepatica in xylem cell walls of Quercus robur. Mycological Research 104, 846-852. Schwarze, F.W.M.R and Ferner, D. (2003). Ganoderma on trees: differentiation of species and studies of invasiveness. Arboricultural Journal 27, Shigo, A.L. & Marx, H.G. (1977). Compartmentalization of decay in trees. Forest Service USDA Agriculture Information Bulletin No. 405, 73pp. White, J. (1998). Estimating the age of large and veteran trees in Britain. Forestry Practice Information Note FCIN 12. Torino, April 1st - 2 nd, 2004 29

Fig. 1

Fig. 2 Veteran Castanea sativa with one strip of functional stem tissue 30 International Congress on The Trees of History

Fig. 3 Ancient Quercus robur with abundant epicormic growth

Fig. 4 Ancient pollard of Carpinus betulus with dieback of new twigs that formed after severe cutting Torino, April 1st - 2 nd, 2004 31

NEW ENTOMOLOGICAL ASPECTS AND STRATEGIES OF LOW ENVIRONMENTAL IMPACT A. Alma Di.Va.P.R.A. – Entomologia e Zoologia applicate all’Ambiente “Carlo Vidano”, Università degli Studi di Torino - Grugliasco (TO), Italy

Broadleaf and coniferous trees are often attacked by different pests, that cause direct and indirect damage and, in the most serious cases, may compromise irreversibly the plant’s functionality. The most common and dangerous infestations are due to leaf-eating moths, beetles and wasps, to wood-eating moths and beetles, and to plant-sucking bugs.

Indigenous species Among the plenty dangerous indigenous species, one can remember the processionary moths Thaumetopoea processionea (L.) and Traumatocampa pityocampa (Denis & Schiffermüller) and the bark beetles, in particular Scolytus multistriatus (Marsham). Thaumetopoea processionea and Traumatocampa pityocampa. They have very hairy larvae, characterized above all by the presence of a lot of stinging hairs. These hairs, very thin and small, detach easily from the body of the larvae and spread on the plants and in the surrounding area. Such hairs may cause skin irritations and serious damage to vertebrates, including man; especially when they affect the eyes or the respiratory mucose. The larvae, normally hide inside silk nests. As they are gregarious, when they get out of their shelters in search of food or of a place where to pupate, they move in long rows. For this peculiar behaviour they are called with the common name of “processionary moths”. Th. processionea lives on different species of deciduous oaks. It overwinters as eggs laid in groups of 200-300 elements, protected by abdominal hairs on the bark of trunks and branches. The gregarious and nocturnal larvae attack at first the younger leaves and on the higher part of the canopy, then they feed on the lower part. At the beginning of July the larvae reach maturity and spin a silk cocoon mixed with hairs and pupate inside the nest or at the base of the infested plants. The adults emerge in August and after some days copulate and lay the overwintering eggs. T. pityocampa commonly known as the pine processionary moth attacks different species of the genera Pinus and Cedrus. The infested pines are more or less defoliated according to the density of nests and are proner to the attacks of xilophagous insects. This moth accomplishes one generation a year. The adults are on the wing in July; the female lays the eggs around a couple of needles so to form a sleeve completely covered by abdominal scales. The larvae hatch at mid August and begin to feed on the needles near the egg cluster; then they erode the needles at the end of the branches after having covered them with silk threads. At the beginning of autumn they build a compact nest suitable to contain the overwintering larvae inside. In the following spring, as soon as they reach maturity, the larvae move in a procession to the ground, where they reach a sunny and dry site and bury themselves and then spin a cocoon in which they remain in diapause and afterwards they complete their metamorphosis. When the environmental conditions are not favourable the diapause lasts until the summer after. The two defoliating moths must be controlled in the larval stage. The interventions are necessary above all in sites visited by people, so to prevent the considerable trouble caused by the larval stinging hairs. As an alternative to the use of synthetic insecticides, one may employ commercial formulations based on Bacillus thuringiensis Berliner variety kurstaki. This product is particularly efficacious against young larvae (1st and 2nd instars). In the case of initial infestations and whenever the size of the trees enables it, one can carry out a manual collection of the nests by cutting the branches bearing them. Against T. pityocampa, the control is compulsory (DM 17-04-1998) if the presence of this insect menaces seriously the production or the survival of the trees or represents a risk for human and animal health. Scolytus multistriatus. This bark beetle is common and present in all Italy. It has settled and spread in all North America. It lives almost exclusively on elms and is the most important spreader of the fungus Ophiostoma ulmi (Schwarz) Nannfeld the agent of the disease called Dutch elm disease. The spores of the fungus are transported by the adults inside the feeding galleries dug at the base of gems and twigs of healthy elm trees. S. multistriatus overwinters in the larval stage inside galleries dug in branches and trunk. In spring the newly emerged adults dig feeding galleries and then the females lay the eggs in galleries dug in the bark. The larvae dig individual galleries until they reach the bark and the sapwood. At the end of summer the new adults are on the wing and give birth to a second generation. 32 International Congress on The Trees of History

Presently there is no perspective to refrain the infestations of this insect and of the disease caused by the fungus; until now no resistant strains of elms have appeared. The only kind of control is prevention, trying to keep the plants in optimal vegetative conditions, effecting, if necessary and possible, also recovery irrigations during the hottest period of summer. Moreover, it is useful to avoid increasing the bark beetle’s populations by felling and destroying the suffering and infested trees. The synthetic aggregating pheromone is more useful for phenologic surveys than for efficient adult mass capture strategies.

New entomological problems Besides the number of problems caused by the activity of the different local pests, with a higher frequency, almost daily, new entomological emergencies have to be faced, due to the incidental introduction of exotic species and in some cases to the sudden and unexpected aggressivity of species that were before indifferent and poorly known. Of the different species reported by several authors, here I consider those that cause the most relevant problems or that are held as potentially dangerous and therefore need the establishment of adequate defense strategies for the safeguard of the infested plants (tab. 1). Table 1. List of the species causing new entomological problems in Italy.

Corythucha ciliata. This Northamerican bug has become the most common insect of plane trees. It was found for the first time in Italy and spread to different countries of south Europe, France and Spain; central Europe, Switzerland, Germany, and Austria; east Europe, Hungary, Rumania, Czech Republic, Slovakia, and Bulgary. The adults that overwintered beneath the bark of the trunk migrate in spring to the foliage and feed on young apical leaves. Young and adults live on the lower leaf page and feed sucking the cytoplasmic contents of the palisade and spongy layer cells. Along the year from two to three generations are completed; at the beginning of autumn the adults move to the trunks for overwintering. In summer the leaves appear completely depigmented and assume a yellowish colour. Much more serious than the aesthetic effect is the physiological damage that is caused to the plant; such problems affect the general vegetative state of the plant and in the most serious cases may reduce the wood growth. The defense from C. ciliata is very difficult. In spite of a great number of local predators that adapted themselves to the exotic species, their action proved to be insufficient in refraining efficiently the infestations. On big trees a control of the pest by chemical treatments is badly effectable, keeping in consideration the volume of the canopy. Good results may be obtained by trunk injections (endotherapic method) of formulations registered for this use. Corythucha arcuata. This new species of the genus Corythucha was recorded for the first time in Europe in 2000 during entomological samplings in a park in the outskirts of Milan. C. arcuata is widespread in Northamerica and in particular in southeast Canada. In its area of origin, this insect lives mostly on different species of the genus Quercus and on Castanea americana; occasionally it was found also on apple and maple. In Italy it was observed Torino, April 1st - 2 nd, 2004 33 especially on Q. robur and less on Q. pubescens and Q. petrea. This insect overwinters in the adult stage and in spring, towards the middle of the month of May, the females lay eggs between the secondary veins of the leaves. The first adults appear towards the middle of June; in one year C. arcuata accomplishes three generations. The trophic activity of young and adults provokes the appearance of obvious depigmented areas on the leaves; in the case of strong infestations there is an early leaf fall at end summer. In USA, in particular on strongly infested ornamental oaks, chemical treatments were carried out, above all to control the first generation of this pest. It is therefore possible to infer that C. arcuata, as it already happened for the congeneric C. ciliata, monophagous on plane, could rapidly spread and cause even strong infestations on oaks, not only in woods, but also in reforestations and in urban green. Illinoia liriodendri. This aphid, recorded until now in Northamerica and Japan, was found for the first time in Europe in parks of north Italy on plants of Liriodendron tulipifera. This species colonized exclusively L. tulipifera; the infested plants are easily identifiable by the shiny leaves covered with abundant honeydew produced by the aphid. The infestation begins with the colonization of the lower leaf page, but soon, as the colony grows, also the upper page is used. The introduction into Europe of this new Nearctic aphid will cause remarkable problems for the use of L. tulipifera, until now widely employed in the realization of parks, gardens, and avenues, since it was without pests. In fact, the abundant honeydew produced by the aphid dirties the underlying surfaces and makes them unenjoyable by the public. The strongly infested plants go through a partial leaf fall. A biological control could be effected by local natural enemies that gradually adapt themselves to the new aphid, thus creating a new biocoenotic complex. Cameraria ohridella. This moth was described for the first time in 1986 in the Republic of Macedonia; in Italy it was recorded in 1992. This leaf miner spread with a surprising speed and with so high population densities as to cause early leaf fall already at end July on Aesculus hippocastanum trees. The white flowered horse chestnut proved to be more susceptible to the infestations of this pest. C. ohridella overwinters in the pupal stage inside the fallen leaves. In spring the females lay isolated eggs on the upper leaf page. The larva digs a mine in which it pupates at maturity. This moth carries out four generations in one year; the first damage to the plants can be observed with considerable populations in correspondence with the development of the second generation. Besides the summer leaf fall, in case of heavy infestations there can be a reshooting and reblooming in late summer. The technique of collecting and eliminating the fallen leaves that host the overwintering chrysalids in the mines, even if it represents a control measure by reducing the initial population in spring of the new year, does not refrain this leaf miner in a sufficient way. The same applies for the action of local parasitoids that, though they show a satisfying capacity of adaptation, as well as it happened in other countries affected by this phytopathological problem, at present they do not appear able to control efficiently this pest. Currently, chemical defense with the use of registered phytosanitary products is the only means available to try to control C. ohridella infestations. Foliar treatments have remarkable execution difficulties, as the trees are of great size and often placed in towns. Therefore, in order to avoid consequent sanitary problems connected with the dispersal of pesticides in the environment, the attention was drawn on endotherapy. Endotherapic treatments can be applied by means of natural absorption or with pressure. The regular translocation of the insecticide, necessary to assure the efficacy of the treatment, is conditioned by abiotic factors (temperature, RH) and above all by the sanitary state of the treated plant. Hyphantria cunea. This moth of Northamerican origin was found in Italy in 1980. It is polyphagous, living on broadleaf trees, preferring mulberry, maple and walnut. The larvae feed on leaves that are enveloped in a silk canvas and eroded at first on the lower page, then they are entirely skeletonized. Normally there are two generations a year, in years or areas with a milder autumn, there can be the beginning of a third generation. Overwintering is in the pupal stage, sheltered in cracks of the trunk and of main branches. When the moth appears with heavy infestations the plants are completely covered with silk and defoliated. In the zones that have been recently colonized, the control of infestations can be made eliminating the first infestations, as much as possible, by cutting and destroying the branches attacked by the larvae. Localized insecticide interventions or treatments on the whole canopy must be carried out on the young larvae, employing preferably formulates based on B. thuringiensis variety kurstaki. Anoplophora malasiaca. This cerambycid of Oriental origin, spread in Japan, Korea, and Taiwan, was reported for the first time in Europe in 2001 from plant material imported into north Italy. It is xylophagous and polyphagous and feeds on 50 species of broadleaf trees. In 34 International Congress on The Trees of History the area of origin its biological cycle lasts one or two years, according to when the eggs are laid. The adults emerge in June; females feed on young leaves and twigs. Eggs are laid singly under the bark at the base of the trunk. The larvae dig galleries and feed on phloem and xylem tissues, weakening the plant and leading it to death. Among the many plants attacked by this cerambycid in Italy, there are: Acer saccharinum, Aesculus hyppocastanum, Carpinus betulus, Fagus sylvatica, Platanus acerifolia and Quercus robur. Very probably, this new pest, favoured also by its high polyphagy, will represent a new problem for broadleaf tree management. In the attempt to control A. malasiaca biologically, research has begun to identify parasitoids and predators of this oriental cerambycid. Dryocosmus kuriphilus. It is a gall wasp of Chinese origin living on Castanea spp., introduced into Japan in 1941, into South Korea in 1961, and into USA in 1974; it was recorded in Italy in 2002. This species carries out one generation a year, at the beginning of summer the females lay the eggs inside the gems. First instar larvae overwinter without showing any obvious alterations on the gems. At vegetative recovery, galls grow at the expense of the shoots and compromise the plant’s development with a consequent decrease of fructification and vigour, in the case of repeated attacks the plant may die. This gall wasp spreads by means of the trade of infested shoots or scions and the flight of females. Pruning and destroying infested shoots may slow down the diffusion of this pest. Keeping in mind the inefficacy of insecticide treatments, in Japan this wasp was controlled biologically by introducing its specific parasitoid Torymus sinensis Kamijo from China. Considering the good results obtained in Japan in 2003, at less than one year from the first record of the exotic pest, a biologic control plan has been set up for the introduction of T. sinensis in Italy. From parasitized D. kuriphilus galls coming from Japan a first nucleus of parasitoids was reared in the laboratory in Italy. In the current year, after further studies on the parasitoid’s population, the opportunity to spread T. sinensis in the field will be evaluated. The expected results are a slow establishment of the parasitoid followed by a rapid decline of the gall wasp populations until the reaching of a biological balance, as it happened in Japan during a period of about five years. As it can be seen, the new entomological emergences, almost always due to exotic insects introduced incidentally, have been growing constantly and worryingly in the last years. The continuous alarm points out on the one hand the difficulties encountered by the institutions in charge of carrying out a punctual and serious check of the biological material imported and on the other hand obliges the researchers to find out endlessly control strategies able to refrain efficiently the new pests without causing repercussions on local biocoenoses and on the environment as a whole. Therefore, whenever possible, it is convenient to employ selective synthetic insecticides, natural insecticides, entomopathogenic microrganisms, and biologic control projects by introducing exotic natural enemies, coming from the same places considered originary of the pest to be controlled, so to reach, usually in a medium or long term, a lasting containment of the pest.

Essential references Bernardinelli I., Zandigiacomo P. (2000) - Prima segnalazione di Corythucha arcuata (Say) (Heteroptera, Tingidae) in Europa. Inftore Fitopatol. 12, 47-49. Brussino G., Bosio G., Baudino M., Giordano R., Ramello F., Melika G. (2002) – Pericoloso insetto esotico per il castagno europeo. L’Informatore Agrario 37, 59-61. Clabassi I., Tomè A. (2000) – Tecniche endoterapiche su ippocastano contro Cameraria ohridella. L’Informatore Agrario 33, 88-91. Colombo M., Limonta L. (2001) – Anoplophora malasiaca Thomson (Coleoptera Cerambycidae Lamiinae Lamiini) in Europe. Boll. Zool. agr. Bachic. Ser. II, 33 (1), 65-68. Grabenweger G., Lethmayer C. (1999) – Occurence and phenology of parasitic Chalcidoidea on the horse chestnut leafminer, Cameraria ohridella Deschka & Dimic (Lep., Gracillariidae). J. Appl. Ent. 123, 257-260. Moriya S., Inoue K., Otake A., Shiga M., Mabuchi M. (1989) – Decline of the chestnut gall wasp population Dryocosmus kuriphilus Yatsumatsu (Hymenoptera: Cynipidae) after the establishment of Torymus sinensis Kamijo (Hymenoptera: Torymidae). Applied Entomology and Zoology 24, 231- 233. Limonta L. (2001) – Una forte infestazione di Illinoia liriodendri (Monell) (Rhynchota Aphididae) nei parchi del Nord Italia. Boll. Zool. agr. Bachic. Ser. II, 33 (2), 133-136. Pollini A., Angelini R. (2001) – I nemici delle piante ornamentali. Ed. L’Informatore Agrario, Milano, 183 pp. Torino, April 1st - 2 nd, 2004 35

CAN VETERAN TREES BE STIMULATED BY MYCORRHIZAL FUNGI? S. Egli Swiss Federal Institute for Forest, Snow and Landscape Research WSL, CH-8903 Birmensdorf, Switzerland

1. Introduction What are mycorrhizal fungi and mycorrhizas The roots of almost all vascular plant species are known to form mutualistic symbioses with a certain group of fungi, so called mycorrhizal fungi. The colonized roots are termed mycorrhizas (“fungus roots”, from the Greek: mykes = mushroom or fungus and rhiza = root). Mycorrhizal fungi - members of the Basidiomycetes, Ascomycetes and Zygomycetes - play a crucial role in plant health by enhancing nutrient acquisition, drought tolerance and pathogen resistance of their hosts (Smith & Read, 1997). In return, the autotrophic plant hosts provide their heterotrophic fungal partners with photosynthetically derived carbon compounds (sugars). Based on morphology and the fungal and plant species involved, several different mycorrhizal types are recognised. The most important are: Vesicular-arbuscular mycorrhizas (VAM) are found on the vast majority of wild and crop plants, and most tropical tree species. They are associations where Zygomycete fungi in the Glomales produce arbuscules, hyphae and vesicles within root cells. Spores are formed in soil or roots. These associations are defined by the presence of arbuscules. VAM fungi are generalists, i.e. they can associate with thousands of different host plant species. About 150 VAM forming species are known worldwide. Ectomycorrhizas (EM) are characteristic of most forest tree species in the temperate and boreal regions of the world - for example pines, spruces, firs, oaks, birches in the Northern Hemisphere and eucalypts in Australia. However, some trees (e.g. willows) can have both ectomycorrhizas and vesicular-arbuscular mycorrhizas. Ectomycorrhizas are associations where Basidiomycetes and other fungi colonise short roots and form short swollen lateral roots covered by a mantle of hyphae. These roots have Hartig net hyphae around the cells in the epidermis or cortex. EM fungi are predominantly host specific, i.e. they form associations with certain tree species or a restricted number of them. About 5’000 EM forming species have been described to date. Orchid mycorrhizas consist of coils of hyphae within roots or stems of plants in the family Orchidaceae. Ericoid mycorrhizas have hyphal coils in outer cells of the narrow “hair roots” of plants in the plant order Ericales Why mycorrhizal fungi are important Mycorrhizal fungi increase plant nutrient supply by extending the volume of soil accessible to plants and by acquiring nutrient forms that would not normally be available to plants. Root colonisation by mycorrhizal fungi can provide protection from parasitic fungi and nematodes. Carbon transfer through EM fungus mycelia connecting different plant species has been measured. Networks of hyphae supported by dominant trees may help seedlings become established or contribute to the growth of shaded understorey plants. Hyphae of VAM fungi are thought to contribute to soil structure by mechanical aggregation of soil particles. Epigeous and hypogeous sporocarps of EM fungi are important food sources for forest inhabiting animals and some of them are economically important as human food resources. How to detect mycorrhizal fungi in the soil Most of the EM fungi produce conspicuous fruitbodies: forest mushrooms such as boletes, amanitas, chanterelles or subterranean truffles. The presence of fruitbodies is evidence for the presence of mycorrhizal mycelium in the soil. However, if there are no fruitbodies apparent, it does not mean that there are no mycorrhizal fungi present in the soil, since EM fungi do not form fruitbodies on a regular basis. The detection of VAM fungi in the soil by the naked eye is entirely impossible, since they do not form visible fruitbodies, but only microscopic spores. Nowadays there are new, highly sophisticated methods of detecting and identifying mycelium of VAM and EM fungi in the soil using molecular tools, such as the T-RFLP method or the DGGE (sequencing of cloned PCR-products). The progress in methodology in this field is very fast-paced. A much easier way is to look at plant roots. If there are mycorrhizal fungi in the soil, they colonise plant roots and form mycorrhizas; this is imperative, for they would 36 International Congress on The Trees of History not be able to survive without doing so. Mycorrhizas can be investigated morphologically and anatomically (morphotyping) or by molecular identification of the fungus by comparing genetic fingerprints of unknown mycorrhizas with a reference data base.

2. Artificial mycorrhizal inoculation The need of tree species for mycorrhizal associations was discovered when attempts to establish plantations of exotic pines failed until the essential mycorrhizal fungi were introduced (Marx, 1980). Since the seventies attempts have been made to artificially colonise seedlings in the nursery with mycelia of EM fungi. The aim was to improve early growth of forest plantations. So-called “controlled inoculation” was regarded as an energy-saving and environment-friendly alternative to chemical fertilizers and pesticides. Today the production of ecto- and endomycorrhizal inoculants is at a commercial level and a wide variety of products is available. Techniques of artificial inoculation There are three main methods of application of mycorrhizal inoculum with regard to the age of the tree to be inoculated: - seedling inoculation in the nursery - inoculation of trees at time of transplanting - inoculation of mature trees at the site Inoculant types vary from simple forms (e.g. inoculation with forest soil) to highly sophisticated aseptically produced inocula based on pure cultures or spores, incorporated into carriers and supplemented with growth stimulating additives, such as hydrogels, natural humates, yucca plant extracts, seaweed extracts, kelp, humus, vitamins, amino acids, or other beneficial soil microorganisms like Trichoderma species or rhizosphere bacteria. EM inoculum can be applied as spores or mycelium grown in pure culture. Mycelium inoculum usually causes faster infection but is more sensitive to desiccation and other environmental factors. VAM fungi can be applied only as spores or as infected roots, because they cannot be grown in pure culture on nutrient media. The fungi are multiplied by infecting roots of an intermediate host through the use of spores.

Table 1: types of inoculum products and application ranges (s = seedling inoculation; t = inoculation at time of transplanting; o = inoculation of mature trees)

Can the success of an artificial inoculation be guaranteed? Artificial mycorrhizal inoculation may be successful only when the following conditions are fulfilled: 1. There is no natural or appropriate inoculum in the soil or the inoculum level is low 2. The species present are less efficient at aiding the plant host than those being introduced 3. The host tree produces enough carbohydrates to keep the symbiotic fungi alive As a result of the fact that almost all vascular plants live in symbiosis with mycorrhizal fungi, these fungi are widely distributed all over the regions of the world covered by vegetation. There are some special situations where the natural mycorrhizal populations can be perturbed or insufficient: on sterile soils, e.g. mine spoils, artificial substrates, or on degraded soils, e.g. in urban environments Torino, April 1st - 2 nd, 2004 37

The success of artificial mycorrhizal inoculation can never be guaranteed for two main reasons: 1. the competition between the introduced and the soilborne fungi. Most soils already contain a complement of mycorrhizal fungi that can out-compete the newly introduced species. 2. the soil conditions may not be adequate for the growth of mycorrhizal fungi.

Costs According to the dosage instructions of the producers the application costs of commercial inoculum range from Euro 0.5 to Euro 10 per thousand seedlings (nursery application) and between Euro 0.25 and Euro 0.70 per tree at time of transplanting. For soil restoration the costs range from Euro 0.1/m2 (surface application) up to Euro 60/m3 (full soil inoculation). Inoculation of mature trees by injection of liquid inoculum into the soil may cost even more, depending on the dimension of the tree and its root system.

Selection of fungi for artificial inoculation: economics versus ecology The first and most important selection criteria is the behaviour of the symbiont in pure culture and the possibilities of producing inoculum in abundant quantities. For EM inoculum the choice is very restricted because only a limited number of species are cultivatable, e.g. Laccaria, Hebeloma, Paxillus. The large and widespread families of Cortinarius or Lactarius are very difficult to take into culture even though they are known as “late-stage” species, i.e. they preferentally colonise mature trees. Seedling inoculation requires early-stage fungi, such as Hebeloma, Laccaria and Paxillus, whereas mature trees should be inoculated with late-stage fungi, such as Boletus or Cortinarius species. Another major criteria for selecting fungal symbionts to be utilized for inoculation of mature trees is their root-colonizing ability and competitiveness against wild symbionts already present in the soil. Artificial ectomycorrhizal inoculation Pisolithus tinctorius spores have been the main component of commercial EM inoculum since the beginning. Fruitbodies of Pisolithus tinctorius fungus produce high quantities of spores, but it can be questioned whether this fungus is a good choice from an ecological point of view. It is known from various studies that this species gives good results on mine spoils, but there is no evidence that this fungus is competitive enough on other soil types. The most important problem is that soil conditions in the landscape may be too variable to be able to make generalizations about the usefulness of artificial inoculation with the few selected species available commercially. Mycorrhizal fungi are - as vascular plants - site and host specific. And above all they are not identical in their effect to the host plant. Some species may have a positive effect, a neutral effect or under certain circumstances even a detrimental effect on the host plant (Klironomos, 2003).

Inoculation of mature trees in urban environments Urban soils are very different to forest soils since they are influenced by human activities and therefore the soil’s natural characteristics that benefit trees are often degraded. They rarely have an organic layer and they may have disrupted soil profiles as the result of organic top layers having been removed or turned into mineral subsoil horizons by construction activities. Often these soils are compacted, have an altered drainage and an elevated pH. Additionally, they are submitted to stresses such as de-icing salt in winter and air pollution from exhaust fumes. All these factors may harm root growth and health of the trees growing on these soils and they also disturb the mycorrhizal flora. Since urban trees have the same biological needs as forest trees, the idea of improving the soil by artificial inoculation with mycorrhizal fungi was born. An important point which makes the inoculation of mature trees problematic compared to seedling inoculation in the nursery, is that the roots of mature trees are normally already colonised by mycorrhizal fungi. In theory, the introduction of an alien fungus into an environment that already is fully occupied by indigenous fungi is less likely to be successful than its use in a situation devoid of such fungi. The inoculation method for mature trees is limited to the injection technique using liquid inoculum, or eventually the application of solid inoculum combined with a mulching procedure. On the other hand seedlings are much easier to inoculate compared to mature trees: the inoculum can be allocated directly to the root system in the nursery by mixing the inoculum into the planting substrate of the seedbed or into the planting pot. The inoculum gets in direct contact with the fine roots and root colonisation can happen easily. The soil can be 38 International Congress on The Trees of History sterilized before inoculation to eliminate competing resident symbionts or pathogenic microorganisms. Such a treatment can not be performed on mature trees.

3. Experiences to date with artificial mycorrhizal inoculation Inoculation of seedlings in the nursery In nursery inoculation there is a large body of experience and hundreds of studies which show the positive effect of artificial inoculation with mycorrhizal fungi on seedlings: they grow faster with less fertilisers. But the key question is what happens with these fungi after outplanting? The existing literature indicates that fungal associations often change when the plants are transplanted into the field.

Inoculation of trees at time of transplanting At present there is very limited unbiased scientific evidence that artificial mycorrhizal inoculation of trees at time of transplanting makes plant establishment more successful or that the inoculated plants grow better over time. Garbaye & Churin (1996) inoculated 8-year-old silver limes (Tilia tomentosa) with three ectomycorhizal fungi. In spite of irregular colonization of the roots by the introduced symbionts, tree growth was significantly stimulated in the three fungal treatments and yellowing of leaves in autumn was delayed. Negative results are reported from Alvarez & Trappe (1983): dusting roots with Pisolithus tinctorius spores even reduced seedling survival in some cases. Pilz and Znerold (1986) inoculated Douglas firs with a slurry of Pisolithus tinctorius spores and concluded that “the application of P.t. spores to a seedling’s roots immediately preceeding outplanting appears to be ineffective” South and Skinner (1998) reported on a study where no benefit was obtained by injecting freeze-dried Rhizopogon spores into the soil after transplanting. Other negative results are published by Martin & Stutz (1994) and Gilman (2001): Inoculation of Argentine mesquite (Prosopis alba) with the VAM fungus Glomus intraradices and of Live oak (Quercus virginiana) with a commercial inoculum, respectively, showed no effect on growth or survival. In contrast, nursery production methods and irrigation had a large and significant impact on water stress, tree death and growth after transplanting. However, adding soil to the planting hole at time of transplanting seems to be more promising. Two studies report positive results in survival and growth of Douglas fir seedlings (Amaranthus & Perry, 1989; Colinas et al., 1994) after adding forest soil to the planting hole.

Inoculation of mature trees at the site There have only been two studies up to now which present results of inoculation of mature trees (Marx et al., 1997; Smiley et al., 1997). Both studies show positive effects of inoculation and/or fertilisation on fine root biomass and mycorrhizal colonisation of up to 250-year-old live oaks (Quercus virginiana). As inoculant a spore suspension of Pisolithus tinctorius was injected into the root system to a depth of 20 cm. No other publications presenting results of inoculation of mature trees exist. This could either be due to a lack of studies or a tendency of reviewers to reject papers that show no significant positive treatment effect.

5. Conclusions The inoculation of mature trees with mycorrhizal fungi is technically possible but the decision of whether an application is advisable or not needs careful analysis of the circumstances. This is not because an inoculation could be injurious to the tree but because the effort and the expenses could be economised if the prospects of success are analysed from a realistic and objective perspective. First of all we have to look at possible reasons for a tree’s loss of vitality, keeping in mind the statement of Buschena (2000): “Remember that interactions between mycorrhizal fungi and other components of the landscape ecosystem are very complex. The problems with your trees may not be related to the lack of mycorrhizal fungi. They quite often may be related to the presence of some other organism or condition that is harmful to the trees.” If the tree is simply too old, inoculation will not make it younger. In addition, if the living conditions of a tree are bad due to unfavourable soil conditions or environmental impacts, inoculation only makes sense if the mycorrhizal flora is suffering from these conditions. We have to consider that the two partners of a mycorrhizal symbiosis are living together in a mutualistic relationship. It is not a one-way-profit system from the fungus to the tree. If the tree is no longer able to sufficiently assimilate carbohydrates, the mycorrhizal fungus will be Torino, April 1st - 2 nd, 2004 39 suffering itself and will no longer be able to fully fulfill its beneficial functions for the tree. Furthermore, if the chemical or physical soil properties are completely unfavourable for the existence of mycorrhizal fungi, it would not make sense to artificially introduce them. Consequently, a reasonable approach of ameliorating growth conditions of trees in urban landscape, or of veteran trees, is to improve the basic conditions for tree growth. Current research suggests that organic soil amendment, particularly the addition of composted mulches, greatly enhances the mycorrhizal status of landscape trees. Another possibility is to protect the trees against unfavourable influences (e.g. de-icing salt), or to select tree species which are more resistant against such factors. If artificial mycorrhizal inoculation is to be evaluated at all, the following points should be considered: - Use only correctly labeled inoculum that clearly states the fungal species and number of propagules. - The inoculum should contain propagules that are alive and effective and that correspond in number to the claims on the label. - Inoculum and inoculation procedures should be lower in cost than possible alternatives (fertilization, pest control, site/soil amelioration). In assessing the prospects of success of artificial inoculation we have to be conscious of the fact that about 99% of positive effects of mycorrhizal fungi on their host plant demonstrated in literature are based on experimental designs under more or less controlled conditions. Observations of the reactions of plants to an inoculation after outplanting to the landscape are very rare. The lack of knowledge in this field is underlined by the existence of only these two previously mentioned publications about artificial inoculation of mature trees under field conditions. One of the authors involved in these two papers refers to this problem in one of his earlier papers (Marx, 1980): “The ultimate proof of the value of inoculation of bare-root or container grown nursery seedlings with specific fungi is their performance under diverse field conditions. Meaningful conclusions can only be obtained from properly designed, installed, and maintained field experiments which include periodic tree measurements and mycorrhizal assessments conducted over several years. Only limited field data of this type is available in the literature.” In regards to mycorrhizal inoculation at outplanting or inoculation of mature trees, this statement is as true today as it was in 1980.

Literature Amaranthus, M.P., Perry, D.A. 1989. Rapid root tip and mycorrhizal formation and increased survival of Douglas fir seedlings after soil transfer. New Forests 3: 259-264. Bonello, P.E. Mycorrhizas in the Urban Landscape. Extension Factsheet, Ohio State University. http://ohioline.osu.edu/hyg-fact/3000/3305.html Buschena, C. 2000. Will mycorrhizal inoculations save your ailing tree? Minnesota Shade Tree Advocate 3(3): 3-4. Colinas, C., Perry, D.A., Molina, R., Amaranthus, M. 1994. Survival and growth of Pseudotsuga menziesii seedlings inoculated with biocid-treated soil at transplanting in a degraded clearcut. Can. J. For. Res. 24: 1741-1749. Garbaye, J., Churin, J.L. 1996. Effect of ectomycorrhizal inoculation at planting on growth and foliage quality of Tilia tomentosa. Journal of Arboriculture 22: 29-34. Garbaye, J., Lohou, C., Laurent, P., Churin, J.L. 1999. Ectomycorrhizal inoculation of avenue trees in Paris. Acta Horticulturae 496: 445-449. Gilman, E. 2001. Effect of nursery production method, irrigation, and inoculation with mycorrhizae- forming fungi on establishment of Quercus virginiana. Journal of Arboriculture 27/1: 30-39. Klironomos, J.N. 2003. Variation in plant response to native and exotic arbuscular mycorrhizal fungi. Ecology 84/9: 2292-2301. Martin, C.A., Stutz, J.C. 1994. Growth of argentine mesquite inoculated with vesicular-arbuscular mycorrhizal fungi. Journal of Arboriculture 20/2: 134-138. Marx, D.H. 1980. Ectomycorrhizal fungus inoculations: a tool for improving forestation practices. In: Mikola, P. (ed.) Tropical Mycorrhiza Research. Oxford University Press: 13-71. Marx, D.H., Ruehle, J.L., Kenney, D.S., Cordell, C.,E, Riffle, J.W., Molina, R.,J., Pawuk, W.H., Navratil, S., Tinus, R.W., Goodwin, O.C. 1982. Commercial Vegetative Inoculum of Pisolithus tinctorius and Inoculation Techniques for Development of Ectomycorrhizae on Container-grown Tree Seedlings. Forest. Sci. 28/2: 373-400. Marx, D.H., Murphy, M., Parrish, T., Marx, S., Haigler, D., Eckhard, D. 1997. Root response of mature live oaks in coastal South Carolina to root zone inoculations with ectomycorrhizal fungal inoculants. Journal of Arboriculture 23(6): 257-263. Smiley, E.T., Marx, D.H., Fraedrich, B.R. 1997. Ectomycorrhizal fungus inoculations of established residential trees. Journal of Arboriculture 23(3): 113-115. Smith, S. E., and Read, D. J. 1997. Mycorrhizal symbiosis. Academic press, London. 40 International Congress on The Trees of History

HOW TO PROMOTE AND ENHANCE THE ROOT VITALITY ON VETERAN TREES: RESPONSES TO NATURAL AND CHEMICAL PRODUCTS G. Watson The Morton Arboretum, Lisle, IL - USA

The Key to Longevity Veteran trees have been defined as “Trees of interest biologically, aesthetically or culturally because of their age, trees in the ancient state of their life, and trees that are old relative to others of the same species” (Helen Read, Veteran Trees – a guide to good management. English Nature 2000). In order to care for these trees properly, and insure their survival for many more years, it is important to try to understand why these trees have been able to live so long already. It has been estimated that Britain may be home to around 80% of Europe’s ancient trees (The Ancient Tree Forum). It doesn’t take the deductive reasoning powers of Sherlock Holmes to realize that the nearly ideal, moist, cool summer/moderate winter climate imposes minimal stress on trees in Britain. The veteran trees seen in photographs are always in open spaces with minimal restrictions above and below ground. The situation is similar in the Pacific coast where most of the very large old trees in the US can be found, and for the giant Kauri trees of New Zealand. Under these conditions, demands on the root system are moderate, and episodes of stress are infrequent and not severe. In contrast, trees planted in the center of American cities in small root spaces, where stress is One of the largest Kauri both frequent and severe, trees in the forests of Northern New Zealand have been estimated to have an average life span of only seven years. The environment must play a major role in longevity. There are other situations where trees can live a very long time. On dry windswept mountaintops of the Great Basin in the western United States grow earth’s oldest living inhabitants, the bristlecone pines (Pinus longaeva, Pinus aristata). Many of the trees living today were seedlings when the pyramids were being constructed over 4,000 years ago, and mature in the time of Christ. In this environment, the roots must find moisture between the rocks, crowns are small, and the Bristlecone pine over trees never get more than 8.3m tall, and usually much 4,000 years old less. These are very specific adaptations to survive in this harsh environment.Though not normally classified as veteran trees, Bonsai trees do fit the definition. These tiny trees can easily live in pots for hundreds of years. What do all these old trees have in common? They have a good balance between the crown and root development. The branches and roots of bonsai trees are pruned regularly to keep them healthy, but small. Traditional pollarding used for centuries on trees of Europe has the same effect of keeping the crown small and rejuvenated, extending the life of the tree almost indefinitely. Once pollarding is discontinued, it is only a matter of time until the tree dies of old age. The crowns of the Bristlecone pine trees usually have much evidence of dieback, and are often very A bonsai tree over 400 years old small with only a small strip of live cambium supporting this partial crown. Even in the nearly ideal climates of Britain and the US Pacific Northwest, many of these very old trees show a Torino, April 1st - 2 nd, 2004 41

history of dieback to rebalance the crown with the root system. In all of these examples, the crown is manipulated by nature or by man to reach a balance with the root system. Promoting good root health is also important in helping veteran trees to reach that optimum above- and below-ground balance.

Soils and Root Growth Healthy soil is required for healthy, vigorous root growth. Roots will naturally develop to the full extent that is possible in the existing environment – poor soils are associated with poor root development. Root growth is influenced by numerous factors supplied by the soil. Most of the fine absorbing roots will usually be found in the upper soil layers regardless of tree size, because conditions for root growth are most often optimum there. Even during periods of drought, the natural forest soil The largest giant sequoia environment can remain moist. This points out the need for tree in California. Note maintaining even soil moisture in the root zone. Root growth dieback in the crown stops in most species when soil moisture is reduced to -500 mbar soil moisture tension. Accelerated root suberization (the deposition of a waterproof layer in the walls of cells near the root surface) restricts absorption and is accelerated in dry soil. Roots do not regain their full capacity for water uptake until new root tips can be produced. When plants are watered immediately after cessation of root elongation, roots may not resume elongation for at least one week. Resumption of root growth takes up to five weeks if water is withheld longer. If the soil becomes too dry, some of the smaller roots may die. Veteran trees must be well adapted to the site where they have been growing for centuries, but subtle changes imposed in recent decades, within the tree’s root zone or surrounding areas, can impact the soil environment immediately surrounding the trees and lead to problems. Soil wetness and related drainage conditions are controlled by a number of factors including: 1) precipitation, 2) soil texture and structure, 3) permeability, 4) infiltration characteristics, and 5) landscape position. Soils are poorly drained if water accumulates on the ground surface, or in the subsoil, for several days or weeks during wet periods. This is especially prevalent in topographically low or flat sites that receive runoff from surrounding areas, even if the slopes are very gradual. Seasonal wetness causes decline in plants not adapted to wet conditions. The importance of soil aeration cannot be overemphasized. Plant roots require oxygen. Roots are generally not sensitive to soil saturation itself, but excessive soil moisture reduces soil aeration because the water replaces the air normally held in the pores of the soil. Compaction reduces air space and compounds the problem. In most soils, 8 to 10 percent oxygen in the soil atmosphere is considered the minimum for good root growth. Below this level, growth is inhibited. With the exclusion of air, roots are killed and cannot take up moisture causing desiccation of foliage. As a result, drowning plants often exhibit the same leaf symptoms as those suffering from drought. Lack of adequate gas exchange in waterlogged soils can also lead to an increase in carbon dioxide, which is toxic to roots in higher than normal concentrations. Several types of air injection equipment have been developed to reduce soil compaction and increase aeration. The effectiveness of these is questionable. They may be most effective in light soils where they are needed the least. There have been no confirmed reports of successfully improving root development as a result of their use. Even when soil conditions are excellent, root systems are normally quite shallow and spread far beyond the branch tips, regardless of tree size and age. Root penetration into deeper soils is limited by most soils. Subsoils often have little pore space and the pore space that is available may be filled with water at certain times during the year. With little oxygen available, roots cannot survive there. At the time of the year when these subsoils begin to dry out, aeration is improved. As soils dry, they often shrink and cracks form up to several meters deep. The cracks help to improve aeration, allowing roots to penetrate deeply to access deep soil moisture when surface moisture may be scarce. Though the amount of root biomass in deep soils is quite small, these roots can be very important for tree survival during drought. These roots will likely die back toward the surface during the next wet season. Though it has not been studied directly, one of the keys to veteran tree survival may be that they are growing in soils that allow unusually deep root penetration that helps them to get through extreme weather periods without stress. 42 International Congress on The Trees of History

Optimizing Root Growth Mulching – The critical aspects of the forest soil environ- ment in which the roots of most tree species evolved must be maintained for good root health. The natural litter and humus covered environment of the forest floor provides an even temperature and supply of moisture, oxygen and nutri- ents to roots near the surface. Mulching has the same effect. A sustained mulch layer can reduce soil compaction, increase soil organic matter, water holding capacity, and biological activity. The result can be a dramatic increase in the development of fine absorbing roots. Compared to bare soil, or competition with lawn grasses, mulch can easily double the fine root density in the soil beneath, and increase it by as much as 15-fold in some circumstances. Roots also grow in the mulch itself, increasing the total surface of the root system even further. Roots of trees normally grow in a symbiotic association with certain soil fungi to form mycorrhizae (means ‘fungus Mulching can increase root root’). These fungi have evolved along with the trees and development substantially are favored by the same conditions that promote root growth. Mulching has been shown to increase development of both fine roots and mycorrhizae, which in turn increases a tree’s ability to absorb available water and nutrients from the soil. Surface mulching is easy and effective in improving soil conditions beneath it over time, but in some situations there has been a desire to actually replace the soil. Development of air and water excavation methods and tools has made it possible to remove soil with minimal damage to even the smallest roots. An early study of partial soil replacement in the root zone of mature trees did show that root development can be improved and twig growth increased. The replaced soil may also favorably affect the soil beneath it, just as mulch does, but it has no effect laterally if a pattern of deep narrow holes is used. Wide shallow areas would be better. Fertilization – Phosphorous has long been thought to promote root growth. There is no strong evidence to support this contention. Studies have shown that there is no increase in root growth associated with phosphorous or potassium fertilization where levels were already adequate. In nutrient-rich zones of the soil, the growth of the main root is reduced while branching of lateral roots is increased resulting in greater fine root development. Similarly, localized applications of nitrogen fertilizer can increase root density in the immediate area. Though the addition of nitrogen fertilizer increases root density near the point of application, this may not represent an increase in the total root mass. Root development in other parts of the root system may be reduced. Excess nitrogen fertilization may reduce overall fine root formation. Fertilization could force the crown to grow excessively, enlarging the crown without enlarging the root system. Increased shoot growth of radiata pine (Pinus radiata) and red maple (Acer ruburm) due to high soil fertility resulted in a lower root:shoot ratio. It is sometimes contended that fertilization will lead to greener, larger leaves and increased carbohydrate projection, which would then provide increased carbohydrate supply to the roots and increase root growth. This reasoning assumes that carbohydrates are in short supply in trees that are growing slowly or showing signs of decline. Large declining white oaks (Quercus alba) with poor root development were shown to have very high levels of stored carbohydrates. However, trees that had been in similar condition at one time, but then subjected to an aggressive fertilization program to bring back the green color and increase shoot growth, had no increased root development and had very low carbohydrate reserves. Fertilization increased the imbalance between the crown and root system. In this case, fertilization of veteran trees should be limited to correcting demonstrated nutrient deficiencies. Tree Growth Regulators – The growth regulator paclobutrazol (PBZ), a gibberellin biosynthesis inhibitor, has been shown to reduce the shoot growth of many species. In some situations, PBZ is also known to increase certain aspects of root growth. As a result of reduced shoot growth and/or root growth stimulation, the effect of PBZ can be to increase root/shoot ratio. Photosynthesis is not reduced by PBZ treatments and increases in root growth may be due partially to increased carbohydrate supply to roots. Higher levels of ABA often associated with PBZ treatment have been shown to maintain growth of roots under drought stress. An increase in fine root development implies a more favorable root/crown Torino, April 1st - 2 nd, 2004 43 balance and less stress in treated trees. Reduced water use and improved water status has been reported after treatment with PBZ. Apparent improvements in vigor, color and drought resistance may be related to a greater capacity of the root system to absorb moisture and mineral nutrients from the soil.

White oak at time of paclobutrazol treatment (left) and 10 years later

Mature, declining white oaks (Quercus alba) were treated with PBZ. Root density nearly doubled in 3 years. Signs of crown improvement began to show (slightly greener color) the second year after treatment and continued for over a decade. New growth was deep green and vigorous and the leaves were not noticeably smaller. The leaves were much less scorched by mid-summer compared to leaves of an untreated tree nearby. This technique is new and untested on large trees that are centuries old, but it may someday prove to be a useful tool for caring for veteran trees. Any tree that can maintain an even physiological balance between the demands of the crown for water and nutrients, and the ability of the root system to supply them, can thrive indefinitely. Veteran trees have been able to do this, or they would not have survived. This same approach can be used to improve health and lengthen the life span of any tree, even those growing on very difficult urban sites.

FOR FURTHER READING Ashokan, P.K., W.R. Chaney, and G.S. Premachandra. 1995. Soil applied paclobutrazol affects leaf water relations and growth of American elm (Ulmus americana L.) seedlings. Plant Growth Reg. Soc. Amer. Quar. 23:1-12. Bausher, M.C. and G. Yelenosky. 1986. Sensitivity of potted citrus plants to top sprays and soil applications of paclobutrazol. HortSci. 21:141-143. Coutts, M.P. and J.J. Philipson. 1976. The influence of mineral nutrition on the root development of trees. I. The growth of Sitka spruce with divided root systems. J. Exp. Bot. 27: 1102-1111. Davis, T.D., N. Sankhla, R.H. Walser and A. Upadhyaya. 1985. Promotion of adventitious root formation on cuttings by paclobutrazol. HortSci. 20:883-884. Hackett, C. 1972. A method of applying nutrients locally to roots under controlled condition, and some morphological effects of locally applied nitrate on the branching of wheat roots. Austral. J. Bioi. Sci. 25:1168-1180. Harris, R. W. 1992. Arboriculture: Integrated Management of Landscape Trees, Shrubs and Vines. Prentice Hall, Englewood Cliffs, NJ. 674pp. Himelick, E.B. and G.W. Watson 1990. Reduction of oak chlorosis with wood chip mulch treatments. J. Arboriculture 16:275-278 Kozlowski, T.T. and S.G. Pallardy. 1997. Growth control in woody plants. Academic Press, New York. 641 pp. Lyr, H. and G. Hoffman. 1967. Growth Rates and growth periodicity of tree roots. Intern. Rev. For. Res. 2: 181-236. Nambiar, E.K.S. 1980. Root configuration and root regeneration in Pinus radiata seedlings. N.Z. J. For. Sci.10:249- 63. Pham, C.H., H.G. Halverson and G.M. Heisler. 1978. Red maple (Acer rubrum L.) growth and foliar nutrient responses to soil fertility level and water regime. Forest Service Research Paper NE-412.

Ruter, J.M. 1994. Growth and landscape establishment of Pyracantha and Juniperus after application of paclobutrazol. HortSci. 29: 1318-1320. Ruter, J.M. and C.A. Martin. 1994. Effects of contrasting climate and paclobutrazol on the growth and water use of two container-grown landscape plants. J. Environ. Hort. 12:27-32. Swietlik, D. and S.S. Miller. 1983. The effect of paclobutrazol on growth and response to water stress of apple seedlings. J. Amer. Soc. Hort. Sci. 108:1076-1080. 44 International Congress on The Trees of History

Wang , S.Y. and M. Faust. 1986. Effect of growth retardants on root formation and polyamine content in apple seedlings. J. Amer. Soc. Hort. Sci. 111:912-917. Watson, G. W. 1994. Root growth response to fertilizers. J. Arboriculture 20:4-8. Watson, G. W. 1988. Organic surface mulch and grass competition influence root development. J. Arboriculture 14:200 203. Watson, G.W. 1991. Attaining root:crown balance in landscape trees. J. Arboric. 17:211 216. Watson, G.W. 1996. Tree root system enhancement with paclobutrazol. J. Arboric. 22:211-217. Watson, G.W., P.K. Kelsey, and K. Woodtli. 1996. Replacing soil in the root zone of mature trees for better growth. J. Arboriculture 22:167-173. Watson, Gary W. 2002. Soil replacement: long-term results. J. Arboriculture 28:229-230 Yeager, T.H. and R.D. Wright. 1981. Influence of nitrogen and phosphorus on shoot:root ratio of Ilex crenata Thumb. I ‘Helleri’. HortScience 16:564-565. Torino, April 1st - 2 nd, 2004 45

ASSESSING ENVIRONMENTAL FUNCTIONS AND VALUES OF VETERAN TREES D.J. Nowak USDA Forest Service, Northeastern Research Station 5 Moon Library, SUNY-ESF Syracuse, NY 13210

Introduction Urban trees can provide many benefits to society. These benefits include improvements in air and water quality, building energy conservation, cooler air temperatures, reductions in ultraviolet (UV) radiation, enhanced property values, and many other environmental and social benefits (Nowak and Dwyer, 2000). These multiple benefits combine to improve urban environmental conditions and associated human health and well-being. However, not all trees are equal in the benefits that they provide for society. Selection of proper species and locations can enhance desired benefits. Another important factor is tree size. Veteran trees – trees that have lived a long time and are significant elements of the landscape – often contribute substantially more benefits to society relative to other (smaller) trees in the landscape. Not only do veteran trees contribute the most cumulative benefits due to their relatively long life span, but if healthy, these trees will also typically contribute the greatest annual benefits per tree. The purpose of this paper is to illustrate, based on field data and modeling from various cities, how the environmental benefits and values of veteran trees differ from smaller, more typical urban trees. The benefits discussed in this paper are: · Air temperature cooling and UV radiation reduction · Building energy conservation · Carbon storage and sequestration · Air pollution removal Though the focus of this paper will be on the environmental benefits of veteran trees, it must be recognized that these trees also often have significant social benefits relative to smaller trees (Dwyer et al., 1991; Barro et al., 1997; Nowak and Dwyer, 2000).

Urban Forests Urban forests include the assemblage of all trees and other vegetation within an urban area. To understand the structure and functions of these forests, data were collected on trees throughout all land uses in selected cities. In the late 1990’s, approximately 200 randomly located 0.04 hectare field plots were measured in Atlanta, GA; Baltimore, MD; Boston, MA; Jersey City, NJ; New York, NY; Philadelphia, PA; Syracuse, NY; and Toronto, Ontario. These field data were combined with local hourly meteorological and pollution concentration data within the Urban Forest Effects (UFORE) model (Nowak and Crane, 2000) to quantify urban tree structure, functions, and values in each city. Results from these analyses were summarized by diameter class to illustrate the difference in benefits by tree size. Detailed methods and field sampling techniques can be found in Nowak et al. (1998, 2000, 2002), Nowak and Crane (2002) and www.fs.fed.us/ne/syracuse. For this paper, veteran trees are defined as trees greater than 76.2 cm in diameter at breast height (1.37 m) (dbh). Results from the cities reveal that typically the majority of trees are less than 15.2 cm in dbh, and less than 3% of the population is veteran trees greater than 76.2 cm in dbh (Table 1). Even though there are relative few veteran trees, these trees averaged between 35 to 65 times more leaf surface area than small trees less than 7.6 cm in dbh in the cities analyzed.

Table 1. Percent of total tree population in selected dbh ranges 46 International Congress on The Trees of History

Temperature and UV Effects Leaf area is a critical factor in determining many environmental benefits of trees. Typically the more healthy functional leaf surface area on a tree, the greater the environmental benefits. Assuming a tree has ample soil moisture and all other factors are equal, trees with a greater leaf surface area will typically transpire more water, thereby leading to greater evaporative cooling (e.g., University of California Cooperative Extension, 2000). Increased canopy cover can help reduce air temperatures, with reported reductions of maximum mid- day air temperatures ranging from 0.04oC to 0.2oC per percent increase in canopy cover (Simpson, 1998). In 1995, a heat wave in Chicago caused 514 heat-related deaths, and a heat wave in London caused a 15% increase in all-cause mortality. Excess mortality during heat waves is greatest with the elderly and people with preexisting illness. Much of this excess mortality from heat waves is related to cardiovascular, cerebrovascular, and respiratory disease (IPCC, 2001). Increased urban canopy cover and leaf area, and its consequent reduction in urban area temperature can have a significant human health impact. Increased leaf area and canopy size will also typically lead to greater shading effects, which consequently can affect the amount of ultraviolet radiation (UV) received by humans. Rates of skin cancer have increased greatly in recent years, and increased ultraviolet B radiation caused by reductions in stratospheric ozone may be responsible for this increase. Epidemiological considerations suggest that routine exposure to UV in urban areas can produce adverse health effects (Heisler and Grant, 2000). As tree leaves typically absorb greater than 90% of ultraviolet radiation reaching its surface, larger tree canopies can lead to greater reductions in UV rays reaching urban inhabitants.

Building Energy Conservation Trees affect local building heating and cooling energy needs by shading buildings and reducing air temperatures in the summer, and by blocking winds in winter. However, trees that shade buildings in winter also can increase heating needs. Energy conservation from trees varies by regional climate, the size and amount of tree foliage, and the location of trees around buildings. Tree arrangements that save energy provide shade primarily on east and west walls and roofs, and wind protection from the direction of prevailing winter winds. Energy use in a house with trees can be 20 to 25% lower per year than that for the same house in an open area (Heisler, 1986). Based on results of energy simulations for 11 different climate zones in the United States (McPherson and Simpson, 1999), large (> 15 m tall) deciduous trees adjacent to buildings have an average effect on building energy use 4 to 27 greater than small deciduous trees (6-10 m tall) in the same position (median value = 9 fold difference between large and small trees). This range is based on the average difference between large and small trees, with one tree at each of the 8 cardinal directions around a post-1980 vintage building. Model results of these trees revealed energy reductions in the cooling season and increased energy use in the heating season in all climate zones analyzed.

Carbon Storage and Sequestration Increasing levels of atmospheric carbon dioxide (CO ) and other “greenhouse” gases 2 (e.g., methane, chlorofluorocarbons, nitrous oxide) are thought by many to be contributing to an increase in atmospheric temperatures by trapping cer­tain wavelengths of heat in the atmosphere. Globally averaged air temperature at the Earth’s surface has increased between 0.3 and 0.6oC since the late 1800’s. A current estimate of the expected rise in average surface air temperature globally is between 1 to 3.5oC by the year 2100 (Hamburg et al., 1997). Global warming is implicated in the recent discovery that floating ice over the Arctic Ocean has thinned from an average thickness of 10 feet in 1950 to less than 6 feet in the late 1990’s, and a large expanse of ice-free water that has opened up at the North Pole in 2000 (Appenzeller, 2000; BBC News, 2000). By storing carbon through their growth process, trees act as a sink for atmospheric CO , 2 a dominant greenhouse gas. Larger trees, due to their increased size, will store larger amounts of carbon in their tissue as approximately half of the dry-weight of a tree is carbon. In addition, large healthy trees will typically be able to sequester more carbon annually than trees with smaller diameters. To estimate monetary value associated with urban tree carbon storage and sequestration, carbon values were multiplied by $20.3/tC based on the estimated marginal social costs of carbon dioxide emissions (Fankhauser, 1994).Based on data from various cities, veteran trees store between 600 to 1,000 times more carbon within their Torino, April 1st - 2 nd, 2004 47 biomass than trees less than 7.6 cm dbh (Table 2). In addition, veteran trees continue to store additional carbon and annually sequester between 30 to 80 times more carbon than small trees less than 7.6 cm dbh (Table 3).

Table 2. Differences in estimated carbon storage and value between small (< 7.6 cm dbh) and veteran (> 76.2 cm dbh) trees in various cities

Table 3. Differences in estimated annual carbon sequestration and value between small (< 7.6 cm dbh) and veteran (> 76.2 cm dbh) trees in various cities

Air Pollution Removal Air pollution is a multibillion dollar problem that affects many major cities worldwide. Air pollution is a significant human health concern as it can cause coughing, headaches, lung, throat, and eye irritation, respiratory and heart disease, and cancer. It is estimated that about 60,000 people die annually in the United States from the effects of particulate pollution (Franchine 1991). In addition, air pollution damages vegetation and various anthropogenic materials. Major air pollutants in urban areas are carbon monoxide (CO), predominantly from automobiles; nitrogen oxides (NO ), mainly from automobiles and stationary combustion x sources; ozone (O ), formed through chemical reactions involving the principal precursors of 3 NO and volatile organic compounds; sulfur dioxide (SO ), emissions mostly from stationary x 2 combustion sources and smelting of ores; and particulate matter. Small particulate matter results from local soils, industrial processes, combustion products, and chemical reactions involving gaseous pollutants. Gaseous pollution removal by trees occurs predominantly through the leaf stomata, though some deposition occurs on the plant surface (e.g., Smith 1990; Fowler 1985; Murphy and Sigmon 1990). During daylight hours when plant leaves are transpiring water and taking up CO , other gases including pollutants are taken up into the leaf. Once inside the leaf, 2 these gases diffuse into intercellular spaces and can be absorbed by water films on inner- leaf surfaces. Pollutant uptake by plants is highly variable as it is regulated by numerous plant, pollutant, and environmental forces (e.g., plant water deficit, light intensity, windspeed, gas solubility in water, leaf size and geometry, etc.) (Smith 1990). 48 International Congress on The Trees of History

Particles can be dry deposited on plant surfaces through sedimentation under the influ- ence of gravity or through impaction resulting from wind. Particles hitting the tree may be retained on the surface, rebound off it, or be retained temporarily and subsequently re- moved (resuspended into air or transported to soil or other surface) (Smith 1990). Thus, vegetation generally is only a temporary retention site for atmospheric particles as particles can be resuspended to the atmosphere, be washed off by rain, or drop to the ground through leaf and twig fall. Trees can also emit volatile organic compounds such as isoprene and monoterpenes into the atmosphere. These compounds are natural chemicals that make up essential oils, resins, and other plant products, and may be useful in attracting pollinators or repelling predators (Kramer and Kozlowski 1979). These compounds can also contribute to ozone formation (Brasseur and Chatfield, 1991). Even though trees may emit VOCs, other at- tributes of trees (air temperature reduction, pollution removal) can lead to reductions in ozone. Comprehensive ozone studies are revealing that increased urban tree canopy cover leads to reduced ozone concentrations (Cardelino and Chameides, 1990; Taha, 1996; Nowak et al., 2000; Luley and Bond, 2002). A significant factor affecting the influence of trees on air pollution is the amount of functional leaf surface area. Veteran trees remove 30 to 65 times more air pollution annually than small trees less than 7.6 cm in diameter in selected cities (Table 4).

Table 4. Differences in estimated annual average air pollution removal and value between small (< 7.6 cm dbh) and veteran (> 76.2 cm dbh) trees in selected cities. Pollution removal is the total for carbon monoxide, nitrogen dioxide, ozone, particulate matter less than 10 microns, and sulfur dioxide. Values are based on median U.S. externality values for each pollutant (Murray, 1994)

Conclusion On a per tree basis, veteran trees typically contribute significantly more environmental benefits and value to society than smaller trees. These beneficial functions provided by veteran trees require that these trees be healthy, functioning elements in the urban landscape. By being healthy, veteran trees offer significantly more leaf surface area to interact with the surrounding environment. The gas exchange exhibited by large, functioning veteran trees can provide significant environmental benefits such as air pollution removal, carbon sequestration, and air temperature reduction. In addition, the relative large leaf surface area of veteran trees often provides more shade than smaller trees, leading to increased potential benefits from reduced building energy use (if trees are located in the proper position around buildings) and reduced exposure to ultraviolet radiation. As veteran trees produce some of the greatest environmental values, these trees can offer the greatest single tree effects to improve human health and well-being in urban areas.

References Appenzeller, T., 2000. Plying a fabled waterway. U.S. News Online. http://www.usnews.com/ usnews/issue/000828/passage.htm (last accessed June, 2001) Barro, S.C., P.H. Gobster, H.W. Schroeder, and S.M. Bartram. 1997. What makes a big tree special? Insights from the Chicagoland treemendous trees program. J. Arboric. 23(6): 239-249. BBC News. 2000. North Pole ice ‘turns to water’. BBC News Online. News.bbc.co.uk/english/ world/americas/newsid_888000/888235.stm (last accessed June, 2001). Brasseur, G.P. and R.B. Chatfield. 1991. The fate of biogenic trace gases in the atmosphere. In: Sharkey, T.D.; Holland, E.A.; Mooney, H.A., eds. Trace gas emissions by plants: Academic Press, New York. pp. 1-27. Torino, April 1st - 2 nd, 2004 49

Cardelino, C.A. and Chameides, W.L. 1990. Natural hydrocarbons, urbanization, and urban ozone. J. Geophys. Res. 95(D9):13,971-13,979. Dwyer, J.F., H.W. Schroeder, and P.H. Gobster. 1991. The significance of urban trees and forests: Toward a deeper understanding of values. J. Arboric. 17(10): 276-284. Fankhauser, S., 1994. The social costs of greenhouse gas emissions: an expected value approach. The Energy Journal 15(2), 157-184. Fowler, D. 1985. Deposition of SO onto plant canopies. In: Winner, W.E.; Mooney, H.A.; Goldstein, 2 R.A. eds. Sulfur dioxide and vegetation. Stanford, CA: Stanford University Press: 389-402. Franchine, P. 1991. Soot kills 60,000 a year in U.S., survey shows. Chicago Sun-Times. June 30. Hamburg, S.P., N. Harris, J. Jaeger, T.R. Karl, M. McFarland, J.F.B. Mitchell, M. Oppenheimer, S. Santer, S. Schneider, K.E. Trenberth, and T.M.L. Wigley. c. 1997. Common questions about climate change. United Nation Environment Programme, World Meteorology Organization. Heisler, G.M. 1986. Energy savings with trees. J. Arboric. 12(5):113 125. Heisler, G.M. and Grant, R.H. 2000. Ultraviolet radiation in urban ecosystems with consideration of effects on human health. Urban Ecosystems 4: 193-229. Intergovernmental Panel on Climate Change. 2001. Climate change 2001: Working group II: Impacts, adaptation, and vulnerability. Chapter 9: Human health. http://www.grida.no/climate/ ipcc_tar/wg2/353.htm (last accessed February, 2004) Kramer, P.J. and T.T. Kozlowski. 1979. Physiology of woody plants. Academic Press, New York. Luley, C.J. and Bond, J. 2002. A plan to integrate management of urban trees into air quality planning. Report to Northeast State Foresters Association. Davey Resource Group, Kent, OH. 73 p. McPherson, E.G. and J.R. Simpson. 1999. Carbon dioxide reduction through urban forestry: Guidelines for professional and volunteer tree planters. USDA Forest Service, Pacific Southwest Research Station, Gen. Tech. Rep. 171. Berkeley, CA. Murray, F.J., L. Marsh. and P.A. Bradford. 1994. New York State energy plan, vol. II: issue reports. New York State Energy Office, Albany, NY. Murphy, C. E. and J.T. Sigmon. 1990. Dry deposition of sulfur and nitrogen oxide gases to forest vegetation. In: Lindberg, S. E.; Page, A. L.; Norton, S. A. eds. Acid precipitation. Volume 3: sources, deposition, and canopy interactions. Springer-Verlag, New York. 217-240. Nowak, D.J., K.L. Civerolo, S.T. Rao, G. Sistla, C.J. Luley, and D.E. Crane. 2000. A modeling study of the impact of urban trees on ozone. Atmos. Environ. 34: 1601-1613. Nowak, D.J., and D.E. Crane. 2000. The Urban Forest Effects (UFORE) Model: quantifying urban forest structure and functions. In: Hansen, M. and T. Burk (Eds.) Integrated Tools for Natural Resources Inventories in the 21st Century. Proc. of the IUFRO Conference. USDA Forest Service General Technical Report NC-212. North Central Research Station, St. Paul, MN. pp. 714-720. Nowak, D.J. and D.E. Crane. 2002. Carbon storage and sequestration by urban trees in the United States. Environ. Poll. 116(3): 381-389. Nowak, D.J., D.E. Crane, J.C. Stevens, and M. Ibarra. 2002. Brooklyn’s Urban Forest. USDA Forest Service, Northeastern Research Station, Gen. Tech. Rep. 290. Newtown Square, PA. Nowak, D.J., D.E. Crane, and J.F. Dwyer. 2002. Compensatory value of urban trees in the United States. J. Arboric. 28(4): 194-199. Nowak, D.J. and J.F. Dwyer. 2000. Understanding the benefits and costs of urban forest ecosystems. In: Kuser, J. (ed.) Urban and Community Forestry in the Northeast. Plenum Publ. New York. pp. 11-25. Nowak, D.J., P.J. McHale, M. Ibarra, D. Crane, J. Stevens, and C. Luley. 1998. Modeling the effects of urban vegetation on air pollution. In: Gryning, S.E. and N. Chaumerliac (eds.) Air Pollution Modeling and Its Application XII. Plenum Press, New York. pp. 399-407. Smith, W. H. 1990. Air pollution and forests. Springer-Verlag, New York. Taha, H. 1996. Modeling impacts of increased urban vegetation on ozone air quality in the South Coast Air Basin. Atmos. Environ. 30(20):3423-3430. Simpson, J.R. 1998. Urban forest impacts on regional cooling and heating energy use: Sacramento County case study. J. Arboric. 24(4):201-214. University of California Cooperative Extension. 2000. A guide to estimating irrigation water needs of landscape plantings in California. California Department of Water Resources, Sacramento, CA. 50 International Congress on The Trees of History

RESTORATION AND MANAGEMENT OF HISTORICAL PARKS G. Bovo, G.M. Cirulli Municipality of Turin – Green Management Section

General What does monumental tree mean? If we try to give a spontaneous and immediate definition, we think of an important tree, a tree of remarkable age and size, worth of particular care. If we want to give this mayby somewhat simplistic definition a more authoritative and exhaustive outline, we find a number of prescriptive references which widen the concept and meaning of monumental tree: - Law 1089/39, absorbed into unified code 490/99, gives the definition of a cultural asset and states that objects being of a historical and artistic interest (and therefore trees too) must be at least 50 years old, states the principle of a public enjoyment of cultural assets, stipulates about authorisations in the case of an intervention of any nature on the cultural asset, imposes the principle of conservation also to private possessors of objects being of a cultural interest, states sanctions in the case of a breach of said principles; - Law 1497/39, “Protection of the beauties of nature”, also includes villas and parks not protected by particular rules but distinguishing for their unusual beauty, provides for the compilation of lists on provincial basis by a dedicated panel; - Unified Code no. 490/99 that collected all environmental laws and rules into a sole law instrument; - Regional Law no. 50 of April 3rd, 1995, to protect and improve Piedmont monumental trees having a high naturalistic and historical value. It is a specific law aimed at identifying the monumental trees and rows, being of an interest from the landscape point of view, that are present on the region and at promoting their protection and improvement. It defines, as monumental trees and rows, being of an interest from the point view of history and culture, as well as environment and landscape: ¨ trees either isolated or belonging to natural or artificial wood formation which can be considered as rare examples of imposing and long-lived trees for their age or size; ¨ trees having a precise reference to events or memories rilevant from a historical or cultural point of view; ¨ tree rows of particular value from the landscape point of view, as monumental trees, and from a historical or cultural point of view, including rows inserted into urban centres. The law is also aimed at producing a census the list of which is published on Piedmont Region Official Bulletin (B.U.R.) and sets up a Technical Committee for the protection and improvement of monumental trees and rows. It is a definitely important measure, specifically focused on monumental trees subject. Besides involving particular regulations, monumental trees have features, quite different from ordinary trees, requiring specific actions and interventions: · they are to a greater extent subjected to meteorological and climatic events (the action of wind, changes in humidity, sudden changes in temperature, excessive solar radiations, .), therefore resulting that it is important to regularly monitor their conditions, mainly after particularly severe events; · they are characterised in the so called “terminal growth”, i.e. crown developed mainly on their terminal portion and very heavy branches accumulating strains and breakage risks, which can be pruned for lightening by cutting out their dry parts, also with the purpose of making light access easier and photosynthesising superface larger; · felling neighbouring trees results in loosing the “wood” effect and making sudden crashes more likely; this is an event which occurred in plenty of instances, both in private homes and public green areas, sometimes with unpleasant consequences; · frequent are problems at root level, which result in a lower growth, thinned out leaves, chlorotic colour; · cavities are more likely to be found where it is possible to intervene both by reducing the crown and restoring its balance and by using dynamic tie rods. The latter is a technical contrivance which is still unfrequently used but could where matched to a sound pruning remarkably contribute to improve the safety coefficient of trees having problems related to performance and steadiness. It results from these short considerations that monumental trees may have health problems, that they may be somehow delicate subjects and that also for these reasons, besides their importance, a historic park and its trees must be considered a heritage to be protected and at the same time shared and kept alive. Torino, April 1st - 2 nd, 2004 51

Cavour park at Santena Benso of Cavour park lies at Santena settlement, a village close to Turin, and, although developing over an area having a rather small size (about 16 hectares), it represents a very interesting example of a historical Park with a public management and use owing to history and tree heritage contaied (several specimens result to have been registered already in 1762). It started as a a private residence and, after a turbulent and articulate history rich in ups and downs, it finally become a public park with characteristics that are atypical with respect to ordinary standards. Benso Family was rooted on Santena region and their presence in this small village is proved by documents already since XII century: it results from this fact that the history and events of the park and and buildings that are present there were closely connected to the chequered fortune of the family. In the second half of XVIII century, a park could be already identified, having a geometric design, made up of four parterres, a vineyard bounded by borders and a stream (Old Santena) crossing the area splitting it into two portions and flowing into Banna torrent; there were also regular curve tree lines bounding garden central visual space. The parterres were then converted into a sole large regular meadow maybe fit out for agricultural purposes. Banna torrent control works go back to the period between XVIII and XIX century. This torrent often overflew into Santena property and settlement. Back to this period goes a project to modify the garden. This project can be attributed to architect Lorenzo Lombardi, who had already devised 1797 Turin Napoleonic Land Use Plan. This was the first complete project of the park, named “Plan Geometrique des Jardines de Santena” [Geometric Plan of the Gardens of Santena], where the main role was assigned to the arrangement of vegetation by using shrubs, hedges, borders. As a matter of fact, no reliable testimonies of this project live on. Therefore, it was either left uncompleted or distroyed by one of Banna torrent floods. Park present shape and size were reached in early XIX century thanks to the arrangement of Abbot of Arvillars, commissioned by Benso Family. As a matter of fact, no evidences proved by documents and reliable confirmations of his contribution exist about this step too. Anyhow, the park results to have had at a “romantic” feature that time, with vegetation elements arranged in groups and groves and winding paths, all this providing an informal atmosphere. Based on the example of main European courts, in Piedmont too the art of building gardens became popular and Xavier Kurten, one of the best known landscapists of the time, was in 1820 appointed Director of the gardens of the House of Savoy and of the park of the residence of Racconigi. The influence of this great landscapist, thanks to his being backed at Savoy court, spread out not only into royal residences but also into numerous residences of nobles. The known landscapist was commissioned to intervene on the park of Santena, also considering that the role of Benso Family wthin Royal Family had now become relevant and that the residence needed to be transformed from an agricultural firm into a country palace. Kurten operated a number of botanical choices on a general plant which was already defined at that time (1830). His botanical choices represent the park artitecture itself. From the avenues, he chose the most significant and representative tree specimens, which were kept isolated or clustered. Evident is the use of compositive categories that are typical of this designer, such as the isolated tree, aligned tree, group and grove, although adapted to park small size. Park area hydrogeological characteristics are one peculiar elements. Already in XVIII century, there was a marshy area because of both neighbouring Banna torrent and Old Santena torrent flowing splitting the property into two portions. Banna torrent control by building a two-metre bank and burying Old Santena torrent allowed to recover the area, even though the nature of the soil did not cange, so that Kurten decided to keep existing ponds providing an aesthetic feature. The so sketched park can be led back to three prevailing elements concerning the landscape that are related to to the project: - a circular path characterised by imposing present trees; - a path, maybe prior to Kurten’s intervention, connecting the Villa to the pond; - a third path, connecting the two, with a more evident panoramic feature. From the intervention by Kurten in the first half of XIX century to nowadays, the park was not subjected to big modifications but for some planting on the celebration of the centenary of the Unification of Italy (in the ’60s) and for some maintenance interventions needed after Banna torrente floods; the most significant floods occurred in 1901 and 1951. In 1958, the City of Turin operated a number of interventions through Gardens and Trees Lines Service in order to make the park more accessible to the public and, on this occasion, 52 International Congress on The Trees of History a hundredth of veteran trees, which were considered to be unstable and dangerous, were felled. A successive opening of the park to the public, joined to a defective conservation management of the tree heritage, forced massive phytosanitary interventions in late ‘80s, with felling of seriously impaired specimens. In this period, there are both a complete inventory of the tree heritage by filing the specimens from a phytopathological point of view integrating visual checks with instrumental analises using a Pressler’s sampling borer (V.T.A. was not yet mentioned) and collaboration with the University of Turin aimed at gaining scientific information and data useful for improving park management. In early ’90s, in the Park, there were made the first stability investigations with V.T.A. (Visual Tree Assessment) method. This technique was at that time innovative. It was used at a national level for the first time. In 1996, Park monitoring was completed with V.T.A. This method has since then been a consolidated practice contributing to define trees health state on a yearly basis. Trees health state is a data that is fundamental in setting maintenance interventions. Between 1994 and 1997, the City of Turin commisioned the University to make a study aimed at trying to investigate on the crash of monumental specimens appearing to be healthy but in retrospect showing limited root development. The study results did not include particularly serious pathological situations and the study identified following contributory factors among possible causes: - abundant water present in surface profiles with resulting root aparatus in surface horizons; - consequent development unbalanced between hypogeous and epigeous portions; - numerous trees slanted as first bed out in clusters, then led into rows; - soil chemical and physical characteristics not contributing to cohesivenss between soil and root. Just to give an idea about figures and connected maintenance needs (in economic terms, without being limited by them), consider that the Park at present includes about 800 tree specimens (580 of them are taller than 10 metres) often having an extraordinary size in crown both height and diameter, the species most abundantly present being the plane (going back to XVIII century for numerous specimens, which are taller than 30 metres), oak (common oak and durmast), hornbeam, cypress. Benso of Cavour park is a particular instance also from property point of view. After chequered fortunes and numerous conveyances of propriety, in 1947, Marquis Visconti Venosta donated the Palace and the buildings of Cavour Museum and Archive to the City of Turin. Since 1988, a covenant, now expiring, has been in force governing the relations among the City of Turin, the City of Santena and the Camillo Cavour Foundation (set up in 1955) and has established the technical and legal terms that are relating to the managemt of assets. The Foundation is managing the buildings (the Palace, Cavour Museum and Archive) and a park portion relevant to them, while park remaining portion is up to Santena Municipality, the two being superseded by the City of Turin to which the management of all area tree property is up in consideration of the specificity of specimens present. Such an articulate and artificial splitting of competence and duties into three bodies is not responsive to functionality criterions and further generates plenty of logistics and management troubles; most of all, considering that two of these bodies (the Foundation and Santena Municipality) are rather unwilling to schedule funds for managing the asset, also because of their actual difficulty in finding dedicated resources, an area overall situation results not being adequate to the importance and history of the park itself. In last months, the paperwork to roll over the already expired covenant has been in progress. The priciple the paperwork is based on is a revival of this historical residence on the whole (Palace, Library and Park) and its innovative element is the identification of a body which will be entrusted with the management of the whole asset and obviously will have to meet regulation constraints and jontly agree upon and operate with both proprietor (the City of Turin) and Public Green in all management choices and actions. The drafting of a park avorall restoration program has been recently (1994) commissioned to achitects skilled in historical residences and gardens. The estate use and management program guide lines have also been identified and defined in this drafting. The project provides to maintain and recover the arrangement, proposed by Kurten, through the analysis of architectural, botanic, landscape and phytosanitary components. It highlights as a negative element the splitting of management competence into more bodies and reckons that the implementation of the restoration program is closely depending on a more functional and organic arrangement, with a lightening of use load through the realisation of a riverine park in the portion now subjected to agricultural use and with an improvement of the distincion among areas uses. Torino, April 1st - 2 nd, 2004 53

About arboreal part, the project provides to: maintain the most abundantly present and most representative species (plates, oaks, limes and hornbeams) as single, twinned or clustered trees; reintroduce clustered minute texture species, and only use coniferous trees for extending sight (thanks to dark leaves) and creating groves within a limited space and time. It proposes to reintroduce either native species or species that became acclimatised thanks to leaf chromatic alterations (copper beech, white popler, catalpa), to be used at points of particular interest. It is desirable that the future manager of the area applies the line guides that have been identified in this restoration program in preparing a new covenant, with the purpose to give back the park and residence the status and role deserved by them.

Monumental trees management and the instance of Santena The subject of managing “aged” tree specimens is quite involving and there are often clashing postions. Recently, in some contexts, it seems that a critical line is prevailing with respect to management choices, which are aimed at keeping alive not perfect specimens, because of economic costs considered unsustainable, perhaps thinking to apply firm and industrial principles where all is depending on economic rules. Urban tree lines and also trees in historical gardens and parks often are not in optimal healthy conditions indeed; in some cases, they are affected by age and hard life together with man, the city and connected needs, with a management which did not prove to be adequate at a both technical and cultural level. Replacing partially impaired specimens by new specimens can make some sense in determined circumstances, but it is not a care for all problems. Monumental trees are to be considered as an integral part of cultural heritage and, therefore, must be treated from the point of view of conservative management, avoiding to compare historical green to conventional urban green, working on terms of maintenance, conservation and restoration. A frequent question made by people or by ourselves is “till when have I to keep (alive) trees?” A reply could be: till they are sure, and longer, if I can. Arboricolture technologies and know-how make it possible to best manage aged tree lines preserving the specimen considered to be valuable and undertaking to reintroduce new ones in valid stational conditions rather than just to step into a breach and show that “something is being made”, either using specimens and trying to keep the original design or through a smooth replacement or an integral reconstruction of arboreal. population Ordinary and extraordinary maintenance interventions in a histotical context must be an integral part of a management plan resulting from the analysis of original project, vegetation component, landscape and architecture knowledhe/significance, aspectations, user safety, and its interactions. Tree management must be based on criterions, that are objective, and not only linked to technical know-how, as well as on the identification of intervention priority levels. This is also to avoid that, within a context characterised in a constant lack of funds, choices are forcedly conditioned by a subjective (or, more correctly, emotional) component. In the City of Turin, there has for some 10 years been developing a cultural transformation process in tree management with the aim of introducing a model which, starting from (technical and territory) knowledge and based on objective criterions, is aimed at optimising the choices and substantially includes three main stepss: - knowledge - planning - action One of main points in this new management model is introducing a planning tool to identify intervention priorities named “Arrangement Plan” (P.d.A.). It is a tool based on the identification of technical and scientific parametars making a snapshot of analysed object (the tree line, in this case), where each pareameter is given a fixed, not weighed out weight (score); the addition of the various scores defines the tree line potential risk level. Used parameters include dimensional, physiological data, linked to trees health state and context where trees are located. By adding the data relating to maintenance history, the urgency level is obtaiend, so a grid is generated, which simply and objectively defines, for each tree line or homogeneous unit, both a score that is linked to the potential risk level and an intervention urgency level index. This tool is used to manage pruning and stability checks and is provided with verification and self-checking mechanisms allowing for analysing and possibly justfying in retrospect the choices that were made. This is a fundamental value, in a sector where management results in responsibilities at civil and penal level. It is a tool which, coupled to the knowledge of the 54 International Congress on The Trees of History region and the experience of cultivation/tree technique, also enables to plan and schedule the interventions. Turin experience showed that, while maintaing the first position to the role of the technician, with his/her know-how and experience, it is useful to use management systems which somehow aseptically and objectively identify risks and priorities. In a linear and somehow homogeneous context, such as the one of a tree line, it is simpler to adopt this management guide line, also because the health state of trees, the presence of anthropic activities force somehow the need of regularly intervening with more or less regular shifts (provided that economic availability allows it). In a reality characterised in differing features, such as the one of a historical park with monumental trees, the point of view is changed, because the identification of a risk index not necessarily must correspond to a concrete action, which could irreversibly damage the specimen, although, on the other hand, a normal event like a dry branch fall can produce serious consequences on oversized trees. Having to manage plenty of historical parks used by the public, it can be useful to transfer this objective and functional management model fitting it to the peculiarity of the arboreal populations of these sites, with the aim of creating a data frame allowing to somehow standardise the approach, being aware that there are faced specimens that are in some way sole specimen, where the priority is to know, not to plan. Tecnichal and operational choices such as stability check, the application of more or less regular pruning shifts on monumental trees can become meaningless and be insufficient to assure asset good management and even obtaining a priority index could be unsuitable to the context. Using “urban tree lines” pda, modifications were made and parameters were introduced being more suitable to the reality of the historical park which were grouped into homogeneous sub-groups, obtaining a set of categories taking into account: - stability analysis with relating risk class; - potential risk from the tree objactively occurring, for its position (target of and exposition to wind), this being an element which can be managed but not modified; - potential risk linked to tree size (hight, diameter, crown) and faults present (rot, stringy branches, slanted trunk, etc..), this being a data which acan be modified and managed with cultivation operations; - morphological and geological peculiarities linked to context, in the case of Santena the presence of the surfice layer which conditions root apparatus growth and tree stability. In this way, there are not obtained any overall final scores, which wuold have been rather useless, but a set of distinct values, which define aframe repreenting the peculiarities of monumental trees in a historical park and identifies “risk areas”, attention thresholds where interventions are to be focused to a greater extent. The different data can be used either disaggregated or together in order to decide maintenance interventions also considering the point where trees are located and personalising choices depending on cases; as an example, on trees with stability problems having a high target, crown reduction operations shall be performed, while isolated trees can just be kept under observation limiting interventions to dry portions removal and periodic stability verification. This data can be trasferred to plans in order to map risk areas and obtain a region deep knowledge visual frame. So a transition is made from the management of a typical urban environment, where, owing to large figures and management needs, the judgement about the tree unit is uniformed and where we are somehow forced to manage trees in the logic of “compulsory” rated interventions, to a management which, although adopting an objective methodology, takes into account both context and particolarities odf specimen which are sole specimens. It is an operation requiring a remarkable expenditure of energy in the preliminary step, but the result achieved is a an easy-to-use tool which does not pervert the technical role and is anyhow the evidence of adequate involvment and care, as well as a summary of what is provided by arboricolture techique and technology as applied to an atypical context. In a reality of this kind taken in account can also be management improvement choices such as elevation check, root inspections, which, in urban contexts, can involve huge difficulties in application and a risk of creating a precedent.

Considerations Tree management probably needs a cold blood or perhaps sound madness, as well as a serenity in facing living being which, by dying, may unfortunately create even serous problems to users and environment.Looking at past texts, you find out that wood rot was considered in XVIII and XIX centuries by our collegues as a natural event, a sign of the age, especially for very old trees, while serenely accepting the cours of nature and time. Perhaps such serenity came from missing legal implications on users’ safety, but also from a more aware Torino, April 1st - 2 nd, 2004 55 relationship between man and nature, where the decay and death of a tree were correctly considered as all natural events. In tree management in last decades a transition occurred from choices borrowed from other fields (namely agriculture), to panic linked to bad events, running after a remedy to dispose of / release from problems, responsibilities, risks. As soon as a serious event occurs linked to the fall of a tree, there is a temptation to react trying to remove the problem, maybe even before understanding what happened and why, without caring about whether making like this it is nullified a heritage of knowledge, experience and results buit up over years. If the point is removing any responsibility, there is a sole reply: not being involved in managing trees or convincing the one who holds the reins that in front of any doubt the problem must be suppressed at the root (fitting, isn’t it? .). In my opinion, it can now be tried to approach again to a serene but aware management concerning the treatment of monumental trees marked by time and man. Research, technique and technology, and current practice have extended the range of choices and management capabilities, while keeping steady the strong points, which are the respect of the dignity of the tree and what is represented by it whlile guaranteeing users’ safety.

Literature AA.VV. – “The gardens of the Prince” – IV International Meeting on Hisorical Parks and Gardens. 22-23-24.09.1994 AA. VV. “Vegetation and the historical garden” – Proficiency Course in “Parks , gardens and green areas” University of Turin, Faculty of Agriculture – Day of study – 22.04.1996 La MARCA O., BOVIO G., BOVO G., SANESI G. - “Methodological aspects in the management plan of the Park of Maddalena – Arboretum Taurinense of Turin” – Abstract from Yearly Review by Italian Acadamy of Forestal Sciences – 1996 NICOLOTTI G., BOVO G. – “Crasshes in monumental trees subjected to uprooting”. Acer 1997. AA. VV. – “The Hisorical Garden: representation, reading and ornamenta species” – National Council of Researches– School of Specialisation in Parks and Gardens – University of Turin, Faculty of Agriculture. Torin May 8th 1998. C. Bertolotto, G. M. Cirulli, P. Odone – “Urban tree lines: diagnostic systems, management of know-how and interventions” – Proceedings of the National Conference on Urban Green – Accademy of the Georgofili – Florence. October 9th-10th, 2002 56 International Congress on The Trees of History

MANAGEMENT OF MONUMENTAL TREES: REVIEW ON THE EFFECTS ON PHYSIOLOGICAL BALANCE AND ON TREE BIOMECHANICS F. Ferrini Dipartimento di Produzione Vegetale - Università di Milano

Introduction It is known that as a tree ages its growth markedly changes and that several physiologi- cal changes are associated with plant aging. Unfortunately, while aging of cells and organs (i.e. leaves) has been deeply studied, only limited information can be found on woody plants considered as a whole. As a matter of fact, though woody plants show significant and predictable patterns of changes in morphology and physiology as they age, the study of the possible mechanisms controlling these changes is quite difficult because of the large biom- ass interested and the complexity of the processes involved which have also arisen some controversies among the different authors. Understanding the growth and the physiological behavior of old trees is important both for ecological studies of natural stands (Ishii et al., 2000) and, as in our case, to know what are the effects on tree physiology and on tree biomechanics of some technical practices which are commonly applied in mature to veteran tree management.

Aspect of aging It is quite difficult to situate exactly the beginning of the aging (senile period) in woody plants, because the processes that regulate aging are not fully understood in these kind of plants like they are in animals and annual plants, which aging and senescence are geneti- cally regulated (Bond, 2000). We may consider that it happens at the moment when both vegetative growth and differentiation phenomena reach their maximum expression. Senility then can be defined as the phase of life that begins when the individual is at the last stage of adultness and it is characterized by erosive processes which conduct toward death. Similarly to what happen in the change from juvenile to mature phase (Greenwood, 1995), there are probably a number of “switches”, either in series or parallel, both endogenous and exogenous that must be activated for the senescence phase to occur. It is evident that at least in some woody plants the absolute quantity of organic matter does not increase during the senile period; on the contrary it diminishes. The changes that take place during this period are mostly endogenous and of physiological and biochemical nature, circumstances that make the bibliographical search not easy. In addition ontoge- netic aging (maturation) in trees has received less attention compared to other research topics because, as already stated, the study of woody plants becomes more difficult with aging and tree size. In spite of some studies published on this subject, it is not easy to distinguish between the effect of age, size or environmental changes connected to aging, much less the interac- tions among these factors. However, new techniques (i.e. analysis of stable isotopes, im- proved approaches for measuring sap flow) and better field equipment are helping to make studies of tree aging more feasible, though we are far from a comprehensive understanding (Bond, 2000). Furthermore there is no full agreements about what the word “aging” really means, because terms related to plants can have a similar or different meaning (Fontanier and Jonkers, 1976; Nooden and Leopold, 1988). As underlined by Trippi (1963) many authors refers to “aging” when they talk about the transition from juvenile phase to adult or senile phase; also when they talk of vegetative and reproductive state (in this case the term “maturation” seems to be more appropriate). Others state that the senescent phase begins when the trees start to deteriorate as a results of damage or disease (Del Tredici, 2000). Paraphrases such as “decreasing vitality” and other definitions have been used for it (Bernatsky, 1978). According to other authors we can describe three different types of aging in plants (Fontanier and Jonkers, 1976; Clark, 1983; Del Tredici, 2000; Fay, 2002). - chronological aging, which is the time that has elapsed in the course of the lifespan of the entire plant or some part of it. - Ontogenetical aging, related to the process of a plant passing through different phases of development (i.e from seedling to senescent phase). The ontogenetical aging process, called maturation or phase change by some authors (Ritchie and Keeley, 1994), is controlled by the meristematic tissues of the tree and it’s not uncommon for different parts of the tree to be in different growth phases at any point in time, as when juvenile suckers originate from Torino, April 1st - 2 nd, 2004 57 fully mature trunk tissues. According to Fontanier and Jonkers (1976), ontogenetical aging is genetically programmed, localized in the meristems, not related to exhaustion, and cannot easily be reversed. - Physiological aging (senescence), referring to the general condition of the whole plant, describes the development as well as the deterioration of the life-support systems of the tree. It represents the negative aspects of aging such as loss of growth vigor, the increased susceptibility to adverse conditions (stresses), etc. These negative aspects gave origin to a new branch of science called phytogerontology which, however, hasn’t developed like oth- ers. Del Tredici (2000) states that physiological aging specifically covers the loss of vigor in the root or shoot system that results from environmental stresses or from the damage caused by wind, fire, ice and snow. In general, the physiological aging process is controlled by the differentiated tissues of the tree. Physiological aging is correlatively influenced and caused by an increase disorganization and exhaustion, and it is not localized in the mer- istems. When not advanced, a reversal is possible (Fontaniers and Jonkers, 1976). This paper will be mainly focused on reviewing the present knowledge with regard to the changes that happen during physiological aging. The major symptoms of this phenomenon are a decrease of the metabolism, decrease in both photosynthesis and respiration, changes in enzymes activity, reduced growth of veg- etative and reproductive tissues, different hydraulic and mechanical properties of woody tissue, increase in dead branches, heartwood formation. Slow wound healing, and changes in resistance to invasion by certain insects and pathogens are other typical features of woody plant senility (Kozlowski, 1971; Fontanier and Jonkers, 1976). Some of the mentioned aspects are the object of other presentation in this Congress so I will focus, according to the title, on the physiological aspects of woody plant aging and on the effect of some management techniques on tree physiology and biomechanics.

Physiological and anatomical changes The phase of aging is characterized by a slowing down of metabolism activity. Some studies have shown that while leaf area of aging trees remains practically constant, its total photosynthetic output slightly declines while respiratory consumption of food increases (due to the increased amount of non-photosynthetic tissue increase), so that the leaves are not able to provide adequate photosynthates for the requirements of the old tree (Kozlowski, 1971; Day et al., 2001). The results obtained from research carried out on conifer trees have shown an age-related trends in both morphology and physiology, an increased compe- tition for nutrients between the various parts of the plant (Moorby and Wareing, 1963) a decrease in photosynthetic rates contributing to declining productivity in old trees (Bond, 2000; Day et al., 2001). Several studies attribute this lower photosynthetic rates in older trees to a reduction in stomatal (or crown) conductance with increasing tree age which, in turn, is caused by a lower hydraulic conductivity in their longer or more complex hydraulic pathways. Based on this some authors have proposed the “hydraulic limitation hypothesis” (Ryan and Yoder, 1997), which states that with increasing tree height growth and produc- tivity decline because of stomatal limitation induced by greater tortuosity (i.e. branch junc- ture), increased hydraulic pathway length resistance and gravity and reduced allocation to roots (Ryan and Yoder, 1997; Bond, 2000; Phillips et al., 2002). Increases in hydraulic resistance could reduce the supply of water for transportation, which in turn could limit stomatal conductance and photosynthesis (Bond, 2000; Coder, 2002). This hypothesis is supported by recent data obtained on Quercus robur mature trees (Rust and Roloff, 2002). In addition to the lower conductivity of xylem in old trees, structural changes in shoot and crown architecture need to be considered when analyzing water relations and photosynthe- sis in mature and declining trees (Rust and Roloff, 2002). However, some contrasting results do exist and it seems that hydraulic limitation, though may be a significant factor determin- ing growth reduction (Battaglia, 2001), does not act on photosynthesis in a simple mecha- nistic way or that other factors play a key role in age-related decline in some species (Day et al., 2001). Actually, as shown by West et al. (1999) conducting tubes must taper and, consequently, the resistance to fluid flow per tube are independent of the total path length and plant size. Becker et al. (2000) state that leaf area:sapwood area ratio rather than path length, may dominate in determining whole plant conductance. These authors also state that the structure of the xylem cells might change as tree grow older to make the wood less resistant to water flow. As a consequence the sapwood area per unit area might increase and the sapwood of large trees might store large amounts of water, thus “buffering” the effect of hydraulic resistance (Bond, 2000; McDowell et al., 2002). 58 International Congress on The Trees of History

According to Coder (2002), several physiological causes are involved in tree aging re- sponses. He reports that 25% of these responses are due to photosynthesis reduction, 10% to sapwood respiration, 20% to soil resource availability, 39% to transport path length and complexity, 5% to detrimental mutations in genetic materials and 1% to reduced defense ability. Grulke et al. (2001) also found a different allocation, with young plants having the highest allocation in roots and foliage and older plant in woody tissues, though their work was limited to mature and not senescence trees. Among the other physiological factors it is known that hormones play a dynamic causal role in endogenous regulation and control of plant senescence (Noodén and Leopold, 1988). While this concept is generally accepted, much is yet to be learnt about their effect on mature tree physiology. Actually, even if research on the classical plant hormones continues to uncover fascinating interactions among these crucial regulatory compounds and how these interactions can affect signal transduction or hormone biosynthesis (Fontanier and Jonkers, 1976; Ross and O’Neill, 2001), the results are mainly related to herbaceous plants and, as such, not always can be directly applied to explain some physiological traits of woody plants.

Vegetative growth Even perfectly healthy and undamaged trees slow down in growth as they reach an advanced age. This lack of vigor may also cause an increase in susceptibility to insect pests and to pathogens. With aging shoots become shorter and weaker, the amount of food absorbed being insufficient to support the whole crown, and as time goes on they gradually die downwards towards the trunk. Clark (1983), referring to other authors’ works, states that as the tree grows larger, the ability to respond to environmental stimuli or timing of that response increases. This can explain why older trees in landscape situations are much more sensitive to site disturbances. Kozlowski (Kozlowski, 1971) affirms that loss of apical domi- nance usually accompanies reduction of shoot growth in aging trees. The same author, referring to a previous research on conifers, states that as the branches became older, they changed their growth angle to a more horizontal, so that the structure of the crown can be strongly modified. This has to be taken into account when managing monumental trees. Changes in wood characteristics In the old trees the wood is not uniform throughout the trunk: there is a definite pattern in its development which reflects the changing activities of the vascular cambium and changes in cellular differentiation at different periods in the life of a tree (Jane, 1970). In fact, several important anatomical changes occur during the aging of trees which influence wood quality. Kozlowski (1971), reviewing other Author’s papers, states that with increasing age the percentage of latewood (wood formed later in the season) increases for a number of years and this change is accompanied by increase in specific gravity and strength. In over-mature trees, however, the specific gravity of wood often declines and little or no latewood is produced. Also the over-mature wood can have a higher lignin and lower α-cellulose content than wood formed when the tree is younger. Another change of paramount importance regarding wood anatomical and mechanical characteristics is the heartwood formation. As known the wood of young trees is entirely made of sapwood which is physiologically active (it contains from 5 up to 40% of living cells) because it serves as an avenue for translocation of water and minerals (Kozlowski, 1971). The changes in wood associated with aging are a result of a genetically controlled process (Shigo, 1984) and are primarily functional, for, after a time, the parenchyma in any zone of wood in a tree loose their its living protoplasts and the vessels and tracheids cease their conductive function (Jane, 1970). It is generally believed that after these changes have taken place, the only functions of the wood are those of support and as a repository for waste materials and is considered physiologically inactive, although it has been suggested that the wood may still serve as water reservoir. As sapwood passes into heartwood, some changes in physiology and anatomy happen. These include altered metabolic rates, changes in enzymatic activity (i.e. increased peroxi- dase activity), starch and food reserves depletion, darkening of xylem associated with deposition of extractives, gums, resinous and phenolic components, tannins, coloring mat- ters, changes in wood density, anatomical changes such as increase pit aspiration in gym- nosperms and formation of tyloses in angiosperms, and changes (decrease) in moisture content (Jane, 1970; Kozlowski, 1971; Gjerdrum, 2003). These changes can have a direct influence on wood disease resistance, because heartwood is less prone to be attacked by Torino, April 1st - 2 nd, 2004 59 fungi and insect due to its higher content in preservatives substances, though this state- ment has been disputed by old and recent studies because there is a sufficient air in the heartwood for fungal growth, while the wetter sapwood does not contain enough air to make it suitable substrate for wood-rotting fungi (Jane, 1970; Read, 2000). Decay of the inner wood can be actually positive because the hollowing are part of a nutrient recycling process and as stated by some authors (Read, 2000), tree can make use of the products of wood decay inside the trunk by producing aerial roots form its above ground parts, which grow into the rotting stem.

Management techniques of veteran trees The problem which quite frequently arises is whether it is worth spending money on very old trees in order to lengthen their existence, or whether they should be left alone and a young tree planted somewhere in the vicinity. No one would spend money in a obvious wreck, but any tree worth keeping is worth some sort of attention. It needs very little, as a rule to keep a tree wind- and water tight (Le Seur, 1934). According to Read (2000) the first thing to be considered is to distinguish two types of veteran trees: those that have been actively managed in the past and those which are not, though in practice, the techniques may not be so diverse. In addition we should bear in mind the location of the tree. Veteran trees located in the urban environment are subjected, compared to those located in the open country, to several stresses which can strongly affect their health and shorten their lifespan; this must be considered when managing these trees. There are numerous management techniques that must reflect the changing and the function and that must consider the long-term consequences of environmental changes (Clark and Matheny, 1991). Some of them (tree securing, use of biostimulants, growth retardants and mycorrhizal fungi) have been extensively reviewed by other speakers in this Congress; therefore they will not be considered in this paper that will try to provide an outline of the literature pertaining to the effects of pruning and, in general, of some cultural techniques on tree function and structure. However, according to Clark and Matheny (1991) we can state that “the maintenance of a balance between growth and the environment is a basic requirement for continue development and longevity .Arborists must strive to main- tain stable growing condition through long-term programs of care and facilitate the restora- tion of balance within a tree whose environment has been disturbed”. The same authors arise a practical question that is: “what management techniques can be applied to a tree to avert or postpone the development of the mortality spiral?”1.

Pruning The first answer to the question is to help the plant to develop a stable structure. Crown structure has a fundamental importance for tree physiological behaviour determining sub- stantially the spatial distribution of the photosynthetic surface, the water loss (evaporation and transpiration) and, as a consequence, directly influencing the mechanisms of water and nutrient uptake and transport. Crown structure also affects the mechanical resistance of the tree though a notable variability exists in the geometric structure due to a great phenotypic plasticity, that makes the schematizations difficult but, on the other hand, allows great manipulation possibility of tree form. In this scenario we can easily guess how pruning techniques can affect tree physiology and have strong effects on tree health. Actually, pruning determines a different partitioning of the total dry weight, with a greater production of new shoots and a smaller development of the structure (branches, trunk and roots). However the growth of such new shoots is proportional to pruning intensity only to a certain extent, over which it decreases. Fontanier and Jonkers (1976) state that a severe pruning of the branches or stems is effective in delaying the time of aging. It shortens the internal transport system and im- proves the supply of the periphery with water and nutrients. This can be regarded as a physiological rejuvenation. Pruning also induces younger buds or tissue to form normal or adventitious shoots, those being more juvenile than those removed. This can be seen as a kind of semi-ontogenetical rejuvenation. Though severe pruning and crown restructure can be required for safety reason, such a rejuvenation cannot be continued indefinitely, because each pruning activates the present meristems, involved the commitment of significant re- sources; the typical response to this kind of pruning is profuse sprouting that can result in energy depletion, dieback, increased susceptibility to secondary pests or decline, thus inflict an additional stress to old (or declining trees), and stimulating their ontogenetical aging (Clark and Matheny, 1991). Furthermore the elevated production of new vegetation 60 International Congress on The Trees of History strongly reduces nutrients reserves, in particular of carbohydrates, stored in the unpruned part of the tree. In fact plants subjected to pruning show alterations in carbohydrates metabolism in comparison with the unpruned plants, in particular at the beginning of the vegetative season, when, in the shoots in active growth, a presence of an elevated level of soluble carbohydrates, above all with regard to the contained in starch, can be detected, while the reserve accumulation phase begins more lately. According to Evans (2004) this kind of pruning has deleterious repercussions on the relative allocations and prioritisation of a tree’s carbohydrates budget. A review on this subject was made by Clair-Maczulajtys et al. (1999). Based on the assumption that reserves are not homogeneously distributed in the tree, but are stored in special areas or “compartments”, in relation to the species, stage of development, environ- mental conditions, and cultural techniques like pruning, they showed how tree pruning (especially when heavy pruning is applied) can induce a decrease in the quantity of reserves (crown volume reduction, foliage removal, new sinks) and determine important changes in their partitioning. They underlined how abrupt changes in tree care, can have deleterious effects on tree health, causing a general decrease of reserves and, as a consequence, reduce the resistance to pathogens and predators and to the environmental factors. Thus, to avoid radical pruning effects on tree structural stability and on pest problems, pollarding can be considered as a real alternative (Coder, 1996). A tree responds to pollarding by building a dense mass of woody fibres around the cutting points. This bulky mass resists decay and effectively divides the vigorous juvenile growth from the aging stem (Harris et al., 1999). Hence, the defensive and structural integrity of the tree is maximized using this pruning system, because pruning cuts are made when biological reactivity of the trees is quite high and living cells quickly react to wounds and environmental changes and can develop a strong defensive reaction (Coder, 1996). Also pollarded trees develop a con- stantly rejuvenated, energy-creating young canopy, on top of an increasingly ancient trunk. This slows the tree’s normal aging processes. However, while some species can positively react to pollarding (Quercus, Platanus, Tilia), some others (Fagus and Acer species) do not always tolerate pruning (Mattheck and Bethge, 1998). According to Raimbault (1995) we can state that pollarded trees anticipate the natural, uninfluenced behaviour of at least some species. Even the hormonal frame of pruned plants can be deeply altered because of the removal and activation of numerous meristems that are, at the same time, hormone producers and users. In particular an increase in the activity of cytochinins, auxins and gibberellins has been found, with some fluctuations according to the phenological phase of the plant. Cytochinins content and activity is very high in the growing shoots of pruned plants, while gibberellins content is relatively low in the bud break phase to significantly increase only later in the season, showing substantial differences among pruned and unpruned plants. The auxins seem to increase above all in the branches following the stimulus induced by cytochinins, even if a strong activity of synthesis of the root system, due to the altered crown/root ratio cannot be excluded. The increase in the auxins and gibberellins synthesis promotes the development of the vascular system and activates nutrient transport, thus intensifying the growth of the new vegetation. Bearing in mind this knowledge about how pruning can influence the physiological balance of a tree it is easy to guess how difficult is to manage veteran trees in order to improve their stability without negatively affecting their physiological balance which, in the long term, can push them ahead into a mortality spiral (Clark and Matheny, 1991). Older trees, due to their health and stage of life, require more attention before pruning. They cannot withstand pruning as easily as younger, vigorously growing trees, because they have limited energy reserves to fight invading diseases and insects, especially at the prun- ing wounds (NAA, 2004), and when they have been subjected for years to irregular pruning which creates zones impoverished in carbohydrates (Clair-Maczulajtys et al.,1999). As a consequence old trees should be pruned only as needed. Pruning should be limited to remove dead, suppressed, structurally weak, diseased and insect damaged branches or to lighten heavy horizontal branches. In general, it is better to remove less than 25% (other authors recommend less than 10%) of the total tree leaf area (or branches) per year (Gilman, 1997; Elmendorf, 1998), or even better, limit the cuts to crown cleaning without removing living tissue (“do as little as possible in the way of cutting”, Read, 2000). It is fundamental to keep in mind that the destabilisation of thinning operations increases exponentially with increasing tree age and height. Niklas (2002) underlined that “when stems are exposed by the removal of neighbouring portion of a tree, parts that were shel- Torino, April 1st - 2 nd, 2004 61 tered and strong might deform or break even under normal wind conditions”. Pruning also shifts the self-loading conditions of branches or roots. This can have negative effect on tree biomechanics by decreasing the safety factor (the quotient of the load capability and the actual load of a structure or the ratio of the breaking stress of a structure to the estimated maximum stress in ordinary use)(Niklas, 1999; 2002). Further, when trees are topped, overpruned, or stressed, they produce epicormic shoots which are weakly attached and prone to mechanical failure (Hayes, 2002). The modelisation of tree mechanical charac- teristics has been subjected to some critics by some researchers who state that also morphological, histological, and physiological aspects must be considered (Fournier-Djimbi and Chanson, 1999). Recently a new failure criterion for non decayed wood has been proposed by Mattheck et al. (2002) based on the Height/Diameter (H/D) ratio that relates a higher mechanical safety and a better biological supply with water and assimilates to tree with a lower H/D ratio. Management techniques (first of all planting not too dense) should be aimed to decrease or maintain a lower H/D ratio. In conclusion, according to Davis (2002) we can state that there is no hard-and-fast rule as to how much an individual tree’s growth can be cut back. Different species can differently react to heavy pruning and disagreement in the literature is not surprising given that different species where studied, and that in many cases the environmental conditions and the historical background differed. Also, as previously stated the negative effects of improper pruning should be taken into greater consideration when dealing with veteran tree in the urban environment and different management techniques might be needed.

Root Pruning Trees in the urban environment are often subjected to heavy root loss due to soil excavation near trunks. This is not obviously a management technique and its long-term effect on tree health and structural stability is really negative (Harris et al., 1999). As a matter of fact, there is a direct relationship between root loss and growth reduction which triggers a negative-feedback loop, alters the root-shoot ratio, stimulate decay and internal defects, and pushes a tree in the mortality spiral. In fact, beside nutritional interactions, there is also evidence that hormones play a role in mediating root-shoot interactions. Auxins produced by the leaves flow downward to the roots and stimulate new root formation and cytochinins, probably the major antisenescence hormone (Noodén and Leopold, 1988), pro- duced by the roots go upward to the leaves, stimulating shoot growth. Altering this balance can have a direct on plant health. As a consequence, we have to be very careful when cutting roots, because, besides increasing uprooting potential (short-term effect), due to the fact that root not adequately anchor the tree against wind and weight, we deeply alter the physiology of the tree (long- term effect). Heavy crown pruning in this case, it is probably not the best way to restore the balance between the root system and the canopy, but we have to consider to stabilize the tree or to reduce the force of the wind against the tree by crown thinning, which, however should not be considered a long-term solution to root loss and deformities (Gilman, 1997; Elmendorf, 1998).

Other cultural techniques As described, pruning is by far the technique that most affects tree growth and physiol- ogy, but there are other treatments that can be done for old trees. All the techniques should be aimed to reduce the stresses of various type both intrinsic to the site (soil physical and chemical characteristics) and extrinsic (severe chilling, heat, drought, dis- eases), that are able to induce or accelerate many changes related to plant senescence. Some of them are directly applied to the plants, some others are aimed to the improvement of soil fertility and to prevent conditions which are known to be the trigger for any kind of disease. However, as stated by Clark and Matheny (1991), each of the treatments may have good and bad consequences on tree health because they can both positively and negatively interact with the development of a stable environment. Coder (2002) indicates several treatments that can be applied to old trees that can be summarized in keeping the tree healthy by establishing good and stable soil and environment conditions. Among them improving soil fertility seems to have a certain effect, although controversy exists about the effect of fertilization on veteran tree physiological health and on the interaction between fertilization and other management technique like pruning. When fertilizing it should be underlined that N efficient uptake occurs during period of active growth and depends on active photosynthesis. If we reduce the photosynthetic 62 International Congress on The Trees of History area, we can negatively affect N uptake. Also high N applications reduce the concentration of defensive compounds increasing the tree’s susceptibility to certain pests (Struve, 2002). Fertilizers should be applied lightly for mature and old trees in late summer or early fall to promote nutrient storage. Mulching can reduce environmental stresses by providing trees with a stable root environment that is cooler and contains more moisture than the surround- ing soil. Mulch can also prevent mechanical damage by keeping machines such as lawnmowers and weedwhips away from the tree’s base. Further, mulch reduce competition from sur- rounding weeds and turf (ISA, 2004).

Conclusion In spite of the progresses made in the different topics related to plant physiology our present knowledge about the process of aging is not fully adequate to enable us to fully explain it. Understanding aging process is important for setting up management techniques to operate on mature or veteran trees. Such information would be also useful in determining how biotic and abiotic stresses contribute to the loss of vigor and eventually lead to mortality in old trees and how these individuals will respond to the different treatments. We believe that it is necessary to point out the need for special studies, in order to elucidate the real ontogenetical significance from the morphological and physiological changes associated with the different phases of life juvenile, adult and senile.

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SURVEY METHODS & DEVELOPMENT OF INNOVATIVE ARBORICULTURAL TECHNIQUES IN KEY UK VETERAN TREE SITES N. Fay Arboricultural Consultant: Treework Environmental Practice, Chairman of the Ancient Tree Forum

Summary The quality and condition of Britain’s old tree heritage is reflected in the great number of ancient tree sites found in the British Isles, reputed to be among the finest in Northern Europe. Environmental arboriculture and veteran tree conservation methods have been influenced by a multidisciplinary approach that considers the tree in co-evolutionary terms, inherently linked to its ecological context. This approach considers the importance of the ageing process and the use of terminology relating to the developmental stages a tree passes through. The interactions between trees, fungi and other dependent organisms are considered, particularly in the light of the need for arboriculture to take account of how tree management can work to maintain or re-establish conditions suitable for a functioning tree- ecosystem. Understanding the rates of decline in old tree populations has been improved considerably in the UK since the development and use of the Specialist Survey Method. Studies of important veteran tree sites indicate that the rate of tree loss may be unsustainable. This in turn threatens the continuity of dependent saproxylic communities. Innovation in arboricultural management techniques has been influenced by observations of natural processes. The recent emergence of environmental arboriculture provides a framework for considering such issues and for developing appropriate practices to manage trees to enhance longevity and biodiversity. Principal among these is the development of Individual Tree Management Plans for veteran trees, which set planned treatments programmes for 30 to 100 years. Environmental arboriculture, while responding to all current conventional arboricultural considerations and practices (including tree hazard management and amenity tree care), offers scope for an interdisciplinary synthesis of perspectives between all those involved in the appreciation of veteran and ancient trees.

Terminology: Veteran & Ancient In the UK the term ‘veteran’ is used to describe both the age and condition of a tree. A ‘veteran tree’ has the anthropomorphic, cultural connotations of a battle-scarred survivor: a valued, old comrade that has been through the tribulations of life. ‘Veteran’ has come to describe the quality of dead wood habitat in trees. The term is widely used, being both accessible to the specialist and to the public imagination. In recent years an increasing appreciation that decay in trees is important for wildlife. As a result, arboricultural techniques have evolved that inflict deliberate damage or wounding on trees to induce conditions suitable for the progression of rot or other niche habitats. This has caused the need to invent and convey unusual concepts, such as ‘to veteranise’ and ‘veteranisation’. These express effects or actions (deliberate or inadvertent) that impact upon trees, causing the development of dead wood habitat features. The terms ‘veteran’, ‘old’ and ‘ancient’ are all used to describe trees that are ‘of interest, biologically, aesthetically or culturally’ (Sissitka 1996) as a product of ‘age or condition’ (Read 2000). Moreover, ‘veteran’ is used to describe an ‘old’ and valued specimen, which may have survived beyond the typical age range for the species’ (Lonsdale 1999). These terms are often used interchangeably. This paper will explore the conceptual difference between the factors of age and condition and why it is important to clarify these concepts for the purposes of developing appropriate criteria for recording the biodiversity value of such trees and for the formulation of appropriate methods for their conservation. In broad terms, ‘old’ and ‘ancient’ refer to age class, while ‘veteran’ refers to habitat condition (Fay 2002). The term ‘ancient tree’ may be understood as an age classification to describe the stage when, after the loss of apical dominance a tree passes beyond full maturity and the crown begins to shed redundant parts and accumulate dead wood. The crown begins to reduce in size (crown retrenchment) and the annual increment (CAI) eventually reduces, compared to earlier developmental stages in the trees growth (White 1998). This is the final stage in the life of the tree (Read 2000) and, where conditions are favourable, can be the longest. While all ancient trees will have habitat features sufficient to qualify them as ‘veteran trees’, all veteran trees will not necessarily have entered into the ‘ancient’ age-class. Mature trees that show a moderate to high level of veteran features are now termed ‘early veterans’. Until recently, the terms veteran and ancient had been used interchangeably, Torino, April 1st - 2 nd, 2004 65 however it is useful to clarify this distinction. For survey purposes, when required to quantify veteran trees to assess the quality of tree habitat, all ancient and early veteran trees will typically be included. When surveying to evaluate the age structure of the tree population, the inventory of the ancient age class will include only those trees past full maturity. Therefore, as there is scope for misinterpretation, it is important that, when using the terms ‘ancient’ and ‘veteran’, the above contextual distinctions are understood and explicit. As the ageing process progresses, dead and dysfunctional woody tissue is colonised by fungi, which change the nature and condition of wood material. Natural damage and shedding of tree parts can lead to trunk hollowing, branch cavities, live stubs, shattered branch ends, loose bark, sap runs and a range of rot types. The organs of the saproxylic fungi (fruiting body, mycelia etc) may in turn be colonised, for example, by specialised invertebrates. This complex saproxylic substrate, held within a living sapwood envelope of the tree, provides specialised niches for different organisms with diverse ‘life-styles’. A recognised exemplary system, developed in the UK, provides an index of conservation value for woody habitats. This is known as the Saproxylic Quality Index, which compares the site-specific species richness of saproxylic Coleoptera (dead wood beetles) against a standard list, for which rarity scores have been assigned (Fowles, Alexander & Key 1999). Colonising saproxylic invertebrates may have very limited powers of dispersal and certain species may only colonise rot sites once circumstances are favourable. The greater the length of time a group of trees exists on a site, the greater the possibility for particular specialised and rare species to colonise dead wood habitat. Alexander notes that six percent of British invertebrate fauna depend on other species that, in turn, depend upon decaying wood. He estimates that as many as 1,700 invertebrate species are dependent on ancient trees (Butler, Alexander & Green 2002). Continuity is therefore a major factor in biodiversity associated with old trees (Alexander 1996 & 1999). UK Context History of Tree Cover: wood-pasture and parkland In the UK, wood-pastures are the natural inheritance of medieval hunting forests, historic parks and wooded commons. Records indicate that there has been continuous grazing in wooded landscapes throughout lowland Britain, dating from the Norman Conquest. These show that large areas of wood-pasture existed both in private ownership and on common land in the eleventh century (Rackham 1993). Recently, the significance of grazing animals in the development of wooded landscapes has been examined with the conclusion that grazers are effectively a natural agent of landscape management. Taking the oak as a focus of study, Vera examines the natural processes involved in wood-pasture mosaic habitats, and concludes that the relationship between herbivores and trees is co-evolutionary (Vera 2000). Grazing history has been a major factor in the formation of the British landscape. Britain has a history of emparkment dating from medieval times. Our ancestors used wooden staves, hedging and walling to enclose deer, and the relics of these boundary features can still be found in many parks. After the Norman Conquest, fallow deer (Dama dama) were introduced and the practice of establishing new parks spread. By the fourteenth century, it is claimed that 3,200 parks were recorded in England, estimated to cover 2% of the country (Rackham 1980). While many original parklands still exist, the Romantic Movement that flourished in the seventeenth and eighteenth century inspired the construction of naturalistic, designed landscapes with formal gardens and features. These parks were associated with the conscious planting of trees of great character, often intended to provide pleasure gardens and framed views. Tree plantings were often superimposed on an existing matrix of old trees (Fay 2001). Parklands today typically contain examples of tree populations dating from the earliest period of recorded emparkment to modern times, including a great number of pollard trees, cut to prevent deer from browsing regrowth. Pollards were cut and managed as ‘working trees’ (Green 1996) for a wide range of produce. The size and frequency of cutting depended on local and regional economic requirements (Read 2000). Principal traditional pollard species include oak (Quercus robur and Q. petraea), hornbeam (Carpinus betulus), beech (Fagus sylvaticus), common lime (Tilia cordata), willow (Salix fragilis et al), ash (Fraxinus excelsior, holly (Ilex aquifolium) and sweet chestnut (Castanea sativa). In the UK, old trees are abundantly found in old growth woods, parklands and wood- pastures, and to a lesser extent in hedgerows, river and boundary banks, commons and churchyards, (Read 2000). In woodlands, their long-term presence is often the result of 66 International Congress on The Trees of History coppice history, where it was periodically necessary to manage and restrict grazing animals to prevent browsing of new growth. The cultural tradition of pollarding exists throughout the European wooded landscape. Old pollards may be seen from the wooded meadows and pastures of Sweden and Finland (Hæggström 1998; Ranius 2000; Slotte 2000) to the silvopastoral ‘La Dehesa’ systems of southern Spain (Montero, San Miguel & Canellas, 1998). They are found in wood-pastures in upland Scotland (Quelch 2000) and in the grazed olive groves of Crete (Rackham & Moody 1996). Their continued presence today owes much to methods of husbandry. The practice of cutting tree crowns above grazing level for produce, while varied by region, culture and species, has ensured the endurance of pollards in the landscape as open grown trees (Green 1996). Pollard wood-use included fodder, firewood and charcoal, fencing, furniture, tannin, wicker- work, and house and boat building, and it is interesting that a very large population of old pollards still exists within a twenty-mile radius of the London conurbation. An example is Epping Forest, with an estimated population of 50,000 veteran trees over 400 years in age, the majority of which are pollards. This forest, like many wood-pasture sites, is characterised by areas of open space, roads, housing and extensive areas of pollards set in grassland and shrub. It historically formed part of the medieval Royal Forest of Waltham, subject to Forest law according to which commoners enjoyed rights of pasture and woodcutting. Many wood- pasture sites passed through different ownerships while retaining their open wooded character, despite periodic attempts to enclose portions and suppress commoners’ rights of use. Since the late eighteenth century, throughout most of Britain, pollard management practices have progressively fallen into disuse. At Royal hunting forests such as Epping Forest, dwindling deer populations coincided with declining Crown interest, illicit enclosure and urban exploitation. Wood-pasture systems are richly present in the UK and widely distributed. Many contain a significant population of pollard trees with a mosaic of habitats, showing continuity and structure remaining unchanged for many centuries. Hatfield Forest is one such example that has been extensively documented. Recorded originally in the Doomsday Book in 1086, it has remained virtually unaltered for over one thousand years, still containing ‘all the elements of a medieval forest’ (Rackham 1998). The ancient trees at this site have been surveyed and monitored, the results of which have been used to inform management prescriptions for environmental arboriculture restoration treatment (Fay & Fay 2000), as will be discussed later in this paper.

Initiatives to Record & Conserve Veteran Trees: Habitat Action Plans The UK Biodiversity Group (1998) refers to lowland wood-pastures and parkland as ‘the product of historic land management systems and represent a vegetation structure rather than being a particular plant community. Typically, this structure consists of large open- grown or high forest trees (often pollards) at various densities, in a matrix of grazed grassland, heathland and/or woodland floras’. Much of the nature conservation effort in Britain is currently directed through Habitat Action Plans (HAPs). One of these is the Lowland Parkland and Wood-Pasture HAP. It recognises that various factors are necessary for the biodiversity of old tree habitat, and in particular, that the high levels of light and warmth afforded by open-grown trees favour special colonising communities. The loss of old trees is identified as a major cause of the decline and poor condition of dead wood habitat and dependent communities. The Common Agricultural Policy (CAP) has caused considerable harm to veteran trees in arable and pasture land. Deep ploughing, the use of herbicides, inorganic fertilisers, wormicides and other veterinary pharmaceutical products, have damaged soil structure, mycorrhizae and other parts of the root ecosystems. In the UK veteran tree populations have suffered from the effects of poor tree and land management. Isolation and fragmentation of wood-pasture habitats are a threat to dependant communities. Where there are large populations of veteran trees with officially recognised nature conservation value, such sites usually have a survey history. However, survey methods are typically inconsistent with respect to veteran tree data collection. While the value of many UK veteran tree sites is acknowledged, the habitat quality and tree condition is poorly documented and understood. This situation is slowly changing. One of the factors influencing the momentum for improvement has been the involvement of arboriculturists with conservationists. During the early 1990s, there was a growing interest in the necessity to compare information gathered about veteran trees. Until that time, no standardised system had been developed. English Nature (UK government agency for implementing nature conservation policy) identified a broad strategy for improving survey data quality and methodology. The Torino, April 1st - 2 nd, 2004 67

Ancient Tree Forum (ATF) is the lead UK NGO for the conservation of ancient trees and their habitat. It is a collaborative group of conservation professionals, specialists and managers. The ATF identified the need for a standardised recording system to collect tree habitat information. This was considered essential to the understanding of the national status of veteran trees through recording and monitoring key factors influencing population dynamics. (Fay & de Berker 2003). A multidisciplinary approach, led by arboriculturists, resulted in the publication of the Specialist Survey Method (SSM). This is the current national standard for veteran tree surveying. It operates on three levels. Level 1 is the introductory standard for non-specialists; Level 2 is the first level technical standard (typically for arborists, foresters, etc.); Level 3 is used by conservation specialists. The SSM records basic tree data (position, species, form, dimensions), dead wood habitat (tears, scars, stubs, hollowing, rot, dead wood), tree associates (flora and fauna) and growing context (damage, shade, management) (Fay & de Berker 1997). Conservation experts claim that Britain contains the greatest number and the best concentrations of old trees in Europe (Alexander, Green & Key 1996). This claim has both raised awareness and stimulated study in attempts to quantify the population. Recent research has shown that surveys using the SSM have recorded over 45,000 veteran trees at key UK sites (Fay & de Berker 2003). Assuming that 1 in 200 trees have been recorded, as a conservative estimate, this would indicate that there are more than 9 million veteran trees in the UK. To date, the traceable investment in nature conservation surveying of old tree habitat using the SSM is an estimated £291,000. While veteran trees may be present in great numbers in the UK, there are disturbing trends. Studies show that many veteran trees are under threat and there is evidence that the future of veteran trees at these UK sites is not promising. Data collected from a number of populations indicates that, even at protected sites, and those that are considered to be in the best condition (Cox & Sanderson 2001), populations are susceptible to unsustainable rates of tree loss, posing a direct threat to the dead wood (saproxylic) communities.

Fig 1:The Bowthorpe wood-pasture oak: Britain’s Fig 2: Ancient tree wood-pasture at Brockworth, largest Quercus robur, (Girth at 1.5m height is Gloucestershire. The fate of many veteran trees in 12.79m) Shed a major part of pollard crown in the UK. Lapsed pollards with crown limbs prone to 2003.This tree is said to be over 1000years old mechanical failure. Often crown limb loss threatens the viability of the entire tree Population Dynamics One of the major ancient tree sites in the UK is Burnham Beeches, occupying 220 hectares of wooded common. In the seventeenth century, there were 3,000 pollard trees. By 1957, this number was reduced to approximately 1,300. In 1990, when survey methods became more detailed, the population numbered 555. By the year 2000, the total had fallen to 463. The rate of population decline in recent decades is typical for many ancient tree sites. At Burnham Beeches, the rate of loss represents 16.6%, which is an average of 1.6 trees per annum (Read 2000). Attrition rates of between 0.9% and 1.8% are common. The main cause is loss from collapse from mechanical failure (as a result of the cessation of pollard practice) (see Fig 1) and rapid decline from environmental impacts (Fay & Rose 2003). 68 International Congress on The Trees of History

Fig 3: Survey of ancient pollards at Ashton Court, Bristol and Lords Bushes, Epping Forest. Data derived from surveys at two key sites of 444 trees and 155 trees respectively, with neglected, lapsed pollards, shows trunk hollowing to be significantly higher at the top of the bole, whereas hollowing is common at the base of maiden veteran trees. Failure trends are the result of heavy pollard branches breaking at mechanically weakened pollard points or tipping the entire tree due to excessive end loading (error bars ± one standard error). (Fay & Rose 2003) Recognition of current rates of loss in old tree populations has resulted arboricultural intervention to mitigate the risks posed to trees.

Modelling a Sustainable Population The key to a sustainable population capable of supporting a functioning ecosystem requires that first an existing ancient tree population is consolidated. Secondly sufficient numbers of trees must remain in the vicinity of the current population to be capable of becoming veteran and then reaching the ancient stage. This may require the recruitment of non-veteran mature trees and veteranising these (to ‘prematurely’ create bridge saproxylic habitats). This treatment involves implementing techniques that mimic natural damage. Tree population dynamics have conventionally been used to model populations based on utility. In this context, full maturity is regarded to be the optimum target age class. Utility considerations of trees places value on the sound wood condition of the main trunk prior to the development of decay. Techniques of tree population management have yet to be developed that favour post-mature age classes. Such an approach requires the assessment of numbers and mortality rates in each age class. It is then necessary to ascertain whether sufficient numbers are present to ensure successors for older age classes to produce a sustainable population structure. Typically this involves considering arboricultural intervention to reduce mortality rates in the older pre-ancient generations. Site management techniques also need to be targeted to enhance tree longevity for all age classes. Management for a sustainable tree population, targeted to maintaining functioning tree ecosystems, must be based on knowledge of tree mortality. This needs to take account of loss in each age class within the overall population. By responding to these factors, the required rate of recruitment into the veteran population can be estimated. This form of modelling can identify expected change in the veteran population over time and is vital to understanding the actual vulnerability of the ecosystem at a particular locality. This method has been applied to a number of sites to identify the safeguard-requirement of younger age- class trees. The need for tree planting is widely recognised. However, the reasons for conserving mature and fully-mature age classes are now better understood. Tree life expectancy in the UK may be progressively being eroded due to human influences on the environment. If the future ancient tree populations are insufficient in size or integrity, local populations of dependant species may collapse. If this takes place then current investment in the conservation of wood-decay ecosystems will fail. It is therefore a priority that resources are targeted to evaluating ancient tree populations, requirements for succession and sustainable management. Management: concepts of environmental arboricultural Compared with the animal kingdom, ageing in trees is not necessarily unidirectional. Trees and fungi may both be described as indeterminate systems (Rayner 1993), equipped with the ability to alter developmental patterns in response to environmental stimuli. The meristematic (embryonic) system provides the tree with the potential for rejuvenation so that at any stage different parts of the tree may be in a different growth phases. Del Tredici refers to the various rejuvenation processes that occur in trees (ontogenetic, natural and physiological) reflecting the way the “ageing clock” is influenced by genetic or environmental factors (del Tredici 2000). Protracted serial rejuvenation in some species of tree is so effective that there is a tendency to near immortality (Pinus longaeva, Tillia cordata, Taxus baccata). Torino, April 1st - 2 nd, 2004 69

Fig 4: Phoenix Crataegus monogyna at Hatfield Forest, Essex

Natural vegetative regeneration in old trees may be considered as a survival strategy. When this occurrence is successful, the re-generated tree is termed a ‘phoenix tree’ (Fay & de Berker 1997). A number of phoenix strategies have been noted in UK fieldwork. Examples include cases where following tree collapse, the specimen layers, establishes roots and second-order laterals become first-order trunks of a successive generation. Similarly, when the adventitious roots become established within a hollow trunk, the roots may eventually change their mode and develop structural functions (and become independent). Hollow ancient trunks have been observed to rot ands break up to form two or more columns, each becoming independent and capable of breaking free from the original system. These processes are significant in the context of continuity of habitat, when considering that the woody substrate of the tree acts as a ‘Noah’s ark’ for the dependent colonising fauna and flora. These observations are significant, as they have influenced arboricultural management practices intended to support strategies for tree longevity. The convergence between arboriculture and other disciplines, particularly with ecology has led to a transformation in the understanding and appreciation of ancient trees, especially when considering the tree as a co-evolutionary partner that has developed in association with colonising species. Significantly, there has been a reconsideration of the interactions between fungi and tree. Much of the arboricultural terminology typically used to describe the presence of fungi in trees, presumes or implies a pathogenic relationship. Ingress is a basic presumption and the presence of fungi in or on trees is generally described in terms of ‘invasion’, with modes of ‘attack’ and degrees of ‘aggression’; implying that the tree has evolved a primarily and comprehensively defensive relationship with respect to fungi. During the 1990s, new insights were gained from investigations into the range of colonising strategies of different fungal species. Mycological research began to surface in the field of arboriculture, introducing notions of complexity not previously recognised. This described the presence of endophytic (dormant or latent) fungi that operate territorially and become visible after bark wounding and dysfunction have occurred. This complexity is evident where natural processes may be observed in sites such as old growth forests and low-intervention wood pasture. Arrays of different fungal modes operate including wood decomposition, recycling, nutrient foraging and pathogenic processes, all potentially organised through mycelial interconnection (Rayner 1993). The perception of the tree-fungi-system as complex, multifunctional and interactive is a vital concept in environmental arboriculture. It is fundamental to comprehending the co-evolution process as a factor of tree longevity and to informing tree health and pathology diagnosis.

New Arboricultural Techniques for Veteran Tree Management In the eyes of environmental arborists, chainsaw cuts result in an unnatural flat plane- surface (i.e. such surfaces are literally not found in nature) and apart from the concern to replicate ‘naturalness of form’, there are further ecological considerations that have promoted work to develop natural fracture pruning methods. Branch breakage (from mechanical weakness and storm damage to trunk and limbs) results in a variety of effects on wood tissue at the 70 International Congress on The Trees of History point of breakage, leading to fibre separation (along the grain) and splintering in various planes (linear, radial and circumferential). This occurrence creates microhabitats that are colonised by microorganisms and succession species.

Fig 5: Viability assessments of veteran oak populations at four key UK ancient tree sites. The Specialist Survey Method has been further developed to enable an arboricultural assessment of tree stability and vitality to be carried out. This is used to inform an assessment of tree viability to allow comparisons between sites and inform30-year individual tree management plans

Interactions between trees and the species that live on them may have developed over exceptionally long periods of time, and as some trees may be several thousand years old, speculation therefore may extend to the relationships between tree longevity and the continuity of the organisms living on and inside the tree, and those living underground that are associated with the rhyzosphere. Over recent decades there has been a prejudice against dead wood in arboriculture, forestry and agriculture. This is now being redressed. There is an emerging trend to value biodiversity and to promote arboricultural practices for the benefit of wildlife, leading to the development of techniques designed to retain (and even create dead wood habitat) in crown management.

Fig 6: Natural and artificial breakage in an oak tree: both show high levels of growth response at Melbury Park, Dorset

Natural Fracture: Techniques that Mimic Natural Processes Coronet cuts - Dead wood management Natural fracture techniques involve pruning methods that are used to mimic the way that tears and fractured ends naturally occur on trunks and branches. A coronet cut is a type of natural fracture technique that is particularly intended to mimic jagged edges characteristically seen on broken branches following storm damage or static limb failure. It is carried out as a pruning treatment to a stub or reduced limb to mimic natural breakage. The form of the coronet cut is designed to shape the branch or trunk end-surface to resemble the fracture that might be imagined following a storm, (such as Beaufort storm force 9/10) and is cut to Torino, April 1st - 2 nd, 2004 71 resemble a broken or shattered appearance. Early experimental work exploring methods of cutting dead branches to mimic natural breakage was carried out at Ashtead Common National Nature Reserve, Surrey. This led to further developments and the current use of coronet cuts in both living and dead limbs. It was first trialed following a catastrophic fire, which seriously scorched, damaged or killed several hundred veteran trees on the Ashtead Common, affecting a significant proportion (10%) of the population of over 2000 veteran oaks at that site (Adam Curtis, James Green and Bob Warnock. 2000). The presence of so many dead trees in an area frequented by the public initially prompted a requirement to remove the trees for public safety. After consideration of the conservation values of the dead wood habitat, it was decided to retain as many standing dead trees as possible, while carrying out varying degrees of reduction to reduce risk of crown or trunk breakage to an acceptable level. Dead wood (over 150mm) was deemed potentially suitable for carrying out this exploratory coronet-cutting work. Earlier attempts at replicating what was observed in nature had varying results. Trials at Stowe Park, Buckinghamshire, were carried out in the early nineties using explosives on dead trees to see what type of fragmented ends would result (Finch 1996). The use of explosives is not now advocated in the UK for both the obvious reason of safety and that outcomes are uncontrollable. The author witnessed similar attempts during a visit to Sweden in 1992, where the Swedish army had been recruited at a nature reserve to use explosives on live trees attempting to recreate habitat-types suitable for rare invertebrates. Other experiments carried out at Windsor Great Park, involved winching off partially cut branches to produce rip or tear-cuts on dead trees. This was in some measure successful, but it proved impossible to predict the appropriate winch-tension necessary to effect breakage. Many trees failed at their roots before the attached branch broke off. As a result such practice has for the most part been stopped as it is deemed to be harmful to the root system. Where trees are scheduled for felling coronet cutting is typically carried out as an alternative in order that a part of the trunk may be safely retained, in reduced-scale as dead wood habitat, following the removal of the scaffold branches. It is also carried out following branch reduction – (usually of second or third-order limbs). Trials took place between 1997 and 1999 to retain as much of dead oak as standing hulks with a reduced branch framework. Many of the truncated trees were experimented upon to promote a natural breakage effect through skilful chainsaw use. This resulted in the first studied attempts at coronet cutting (The practice was so called because of the crown-like appearance of the branch ends). It is noteworthy that this was well received by the public. Retained standing trunks have been termed ‘Monoliths’ (Alexander, Green & Key 1993) and are defined as those trees where tree removal would normally be required but are retained as standing trunks in reduced and stabilised form (usually at some 4m to 6m height) as dead wood habitat. It is necessary to re-inspect monoliths to assess and address tree stability and the risks posed, as with any standing tree. As aerial deadwood is valuable habitat, its removal is only specified where its presence about the tree is considered a threat to tree stability or public safety. In such cases, the removal of dead wood should apply only to the material that is considered unstable and prone to failure. Where dead wood removal is proposed it should be restricted to those aspects of the crown where dead wood failure may cause damage or harm. Elsewhere, dead wood may be retained and reduced in extent to stable proportions (Davis, Fay & Mynors 2000). It is noted that with oak, hardened dead aerial branches can often be retained without undue risk, however where risks may be present from dead wood breakage, it is essential that this is assessed and managed as with any part of the tree. As a result of these developments in environmental arboriculture, current guidelines for risk management of aerial dead wood now frequently stipulates that aerial dead wood can be preserved, subject to an assessment of its condition so that it may be retained in stable form (with reduced lever arm and end-loading).

Coronet cuts-Live wood management Currently the techniques involved in dead wood management are now also considered in the pruning of live amenity trees. Since the work at Ashtead, some pioneering work has been carried out by arboricultural practices in the UK. Treework Environmental Practice and others involved in environmental arboriculture have extended this form of dead wood management to the management of living trees to promote dead wood habitat (Fay 2002). This practice is termed ‘veteranisation’ (Cowan 2003). 72 International Congress on The Trees of History

Fig 7: Coronet cut on live Quercus robur stub at Richmond Park, Surrey

The general guideline for this technique requires the selection of potentially suitable stubs for retention. These are cut at a minimum distance that is approximately five times the diameter of the branch when measured at the point of attachment to the stem or higher order branch. Suitable branches will have a diameter greater than 150mm in diameter. The stub length is estimated from the point of attachment with the parent higher order member. Stubs are cut into a coronet appearance through skilful chainsaw use. Live branches may be selected for this treatment where crown reduction (see retrenchment pruning) is being carried out. A proportion of suitable live limbs (up to 15%) are typically selected for coronet cutting. This type of natural fracture pruning is applied to non-crucial structural members only. Cutting is carried out to give the appearance of deep uneven, shattered ends; optimally with an acute angle. Where occasional major stems require heavy reduction truncation, the final cuts are varied to promote a jagged finish.

Retrenchment pruning Retrenchment pruning is a term coined by Paul Muir of Treework Environmental Practice to describe the technique. It is a refinement of the concept of restoration pruning referred to in the European Treeworker Handbook (EAC 2000) and has been developed to imitate the natural process of crown ageing, often referred to as the stage beyond full maturity when the tree ‘grows downwards’ (Green 1996). The term ‘crown retrenchment’ is used to describe the way in which peripheral dieback occurs as the tree redirects energy and growth to the formation of a consolidated lower region of the crown. Crown retrenchment pruning is used to extend tree viability, (both in relation to vitality and stability), whilst retaining habitat features associated with ageing. Retrenchment pruning is a technique that can be used to reduce the potential for a fully mature, late-mature or ancient tree to collapse or disintegrate under its own weight, as a result of excessive end-loading associated with long or weakly attached limbs. It is carried out according to a long term programme - typically termed ‘Individual Tree Management Plan’ (the ITMP). The ITMP may typically extend up to thirty years. The technique is also used in trees where incipient decline appears to result from excessive transportation distances from the root system to the crown periphery. While this technique may have a general value, it is especially useful for managing lapsed old pollards and mature maiden trees that show signs of dieback, physiological stress or a tendency to long-term limb breakage (i.e., not where there is an urgent need to reduce crown limbs to avoid breakage). The practice of retrenchment pruning follows a detailed inspection, which assesses the viability of the tree in terms of current vitality, the probability of tree loss as a result of Torino, April 1st - 2 nd, 2004 73 expected decline in vitality or from structural collapse. This assessment informs decisions as to whether retrenchment pruning is appropriate. If the tree is an important specimen prone to imminent mechanical failure, threatening its viability, then gradual retrenchment treatment would not be appropriate. In such cases an alternative method is suggested involving significant reduction to selected failure-prone limbs (see Read 2000, pp 42-43). If the tree shows a moderate level of vitality and mechanical stability appears vulnerable in the long term, while being sufficient to support a moderately reduced crown structure in the short term, then retrenchment pruning may be carried out to restructure the framework. The Individual Tree Management Plan will follow from the assessment of tree viability, and will specify the first stage of treatment (possibly involving as little as 10% or less than a metre reduction). The Plan sets an ultimate height above the bolling or from ground level (Target Height) to which the crown will eventually be reduced at the time of Plan completion. In addition this will specify the return period (Retrenchment Cycle) for future retrenchment pruning visits, typically 3 to 5 years. Lastly the Plan Duration is set. This is overall duration for the programme of treatments up to completion (usually between 12 to 30 years, but sometimes up to 100 years). Retrenchment pruning is carried out in stages and involves the reduction of the tree height and the extent of crown growth over a protracted period of time. It is carried out to 4th or 5th order branching, often within the constraints of using a turbo saw and secateurs, and usually involves at least three return treatments involving periodic monitoring and allowing re-growth to occur in the interim. The process is intended to promote early crown stabilisation and reduce the risk of traumatic structural failure by reducing the lever arm, while at the same time increasing light penetration to inner aspects of the scaffold limbs. Epicormic growth arising from these lower and internal crown areas have the potential of becoming the scaffold limbs of a future reduced crown framework. The method is intended to stimulate internal and lower crown growth (rejuvenation) through reducing apical dominance to redirect hormonal growth regulation capable of re-iterative stimulation. Eventually retrenchment pruning will create a reduced crown framework over the Plan Duration. For trees with moderate to high vitality, the first stage of retrenchment pruning should avoid overall reduction by more than 20%. For trees with low vitality the first stage of retrenchment pruning is typically less than 10%. Where tree stability is already heavily compromised reduction levels should be sufficient to reduce the lever arm to an acceptable level.

Conclusion In the UK, governmental and non-governmental conservation agencies have recognised the value of old trees for wildlife. Through the work of a number of pioneering conservationists, drawn mainly from the ranks of the Ancient Tree Forum and the Woodland Trust (lead voluntary agencies with interest in old tree conservation), understanding of the biological and cultural values has been improved. A wide consultation between owners, managers, conservationists and professionals, involved in the study and care of old trees, has led to a number of publications to guide survey methodology and management. The publication of the Specialist Survey Method as the UK national standard for surveying veteran trees has provided the framework for consistent recording and data collection. While the British Isles is recognised to contain a very high proportion of Northern Europe’s ancient trees, population studies at key UK wood-pasture sites have shown that there is an unacceptable rate of tree failure. This recognition and the convergence between arboriculture and ecology has resulted in an improved understanding of the ageing process in trees. Fungi are now understood to have a principally benign interactive relationship in the tree-fungi-system, creating conditions for colonisation by dependent species, many of which have poor powers of dispersal. The UK arboricultural profession is beginning to recognise that it is necessary to develop appropriate tree management techniques to foster optimum conditions suitable for the continuity and diversity of saproxylic species-rich communities. As the ancient tree is the ‘ark’ that carries these species through time, it is necessary that the features of value to dependent organisms are a focus for management practice. This approach has led to arboricultural innovations, such as the development of natural fracture techniques, coronet cutting and retrenchment pruning, and particularly the need to manage old trees in terms of appropriate space and time. When determining work programmes for old trees, management processes need to consider the whole environment of the tree’s root-space and soil ecosystem. The conceptual framework for management prescriptions should consider the ‘tree-time’ (not human economic- time) necessary to implement a long-term Individual Tree Management Plan. 74 International Congress on The Trees of History

Acknowledgement I am grateful to Ted Green and Ben Rose for their help, comments and suggestions. I am immensely grateful to Ellen Fay for her help in typing this paper. Treework Environmental Practice can be contacted on its website: www.treeworks.co.uk The Ancient Tree Forum may be contacted on their website: www.woodland-trust.org.uk/ ancient-tree-forum

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Read, H.J. (2000). Burnham Beeches Pollard Work Programme, 2000 - 2006, Corporation of London (Unpublished). Cox, J. & Sanderson, N. (2001). Livestock grazing in National Trust Parklands – its impacts on tree health and habitat. The National Trust Estates Department, Cirencester. Sisitka, L (1996) Guide to the care of ancient tree. Veteran Tree Initiative, English Nature) Slotte, H. (2000). Lovtatlet I Swerige och pa Aland – Meoder och Paverkan pa landskapet. Doctoral Thesis, Swedish University of Agricultural Sciences, Dep. Of Landscape Planning. Uppsala. UK Biodiversity Group (1998). UK Biodiversity Group Tranche 2 Action Plans – Volume II: Terrestrial and freshwater habitats. Species and habitat action plans. English Nature. Vera, F.W.M. (2000). Grazing Ecology and Forest History. Oxford: CABI. White, J. (1998) Estimating the Age of Large and Veteran Trees in Britain. Information Note, Forestry Commission, Edinburgh. 76 International Congress on The Trees of History

SECURING OF BREAK-ENDANGERED TREE CROWNS Klaus Schröder Urban Forestry Service - Osnabrück

Abstract Breaking-off of crown parts, forks and large branches are the most common types of failure of urban trees (WILDE, 1996), resulting in substantial damage to objects and persons. Additionally, the trees are also often irreversibly damaged. Reasons for this type of failure usually include bark in forks, decay or fractures in branches. As an alternative to lop crowns or felling hazardous trees, systems for securing of break-endangered tree crowns were developed. One of the first of these systems was the double belt “System Osnabrück”, conceived by the green-department of the City of Osnabrück, Germany (SCHRÖDER, 1990).

Introduction Creatures of nature are normally adapted to withstand weather because regular recurrent situations have resulted in optimising processes of permanent adaption and selection over a long period of time. As an example of such creations of nature, trees are often exposed to extreme weather and they must resist storm, rain, snow and ice. Forces with an impact of some tons must be withstood. The experience of arborists shows, that straight grown trees, as well as certain types of branches best resist the rigours of the weather, whereas other shapes fail in this respect under the same conditions. Rugged tree crowns can be achieved with simple methods such as planting correctly grown trees and proper breeding pruning adapted to the actual development of the trees. Consequently, the implementation of crown securing systems would not become necessary. However, in case of the old tree population with problematic crowns preventive measures cannot help and it is for these old trees that crown securing systems have been developed. In Germany, the law requires that the breaking-off of parts of trees must be prevented, according to the decision of the Federal Court from 21. January 1965 concerning the legal duty to maintain safety. It states amongst other things, that “the responsible party must remove trees and parts thereof which endanger traffic, particularly in those cases when these are no longer steadfast or parts thereof are in danger of breaking off” (BRELOER 1996). Securing break-endangered crowns is therefore an alternative to felling or lop crowns and offers an acceptable implementation of the law which requires the removal of above mentioned dangers.

Left illustration: So called “pressure forks” are optimised for withstanding pressure in the forking area. Nonetheless, the narrowest point between the stems is exposed to great tension in the contact zone when the stems are bent by weather. The cross section shows, that there is bark enclosed in the contact area of the fork and only the outer annual rings have grown together. This type of fork breaks relatively often under traction power. Therefore, securing is important in most cases. Central illustration: So called “tension forks” are normally naturally well-formed. These are not at risk of breaking any more often than other healthy parts of trees. Right illustration: The installation of a crown securing system (break-securing) works like the pivot of a seesaw. The swing of the stems away from each other is transformed and results in pressure on the forking, for which this area is optimally shaped. Consequently, the break can be avoided. (Illustration by / comments according to MATTHECK) Torino, April 1st - 2 nd, 2004 77

Illustration of Crown Securing Systems (Figures and parts of the text in support of the German rules and regulations for tree care methods - volume 2001 – “ZTV-Baumpflege- Ausgabe 2001”-)

Crown Anchoring System: Made of threaded bolts, steel cable, and fastening material. NONE-injury free installation.

The extent of injury caused by the installation of crown anchoring systems is so great that this system should not be used in the future

Hollow Rope Securing Systems: Made of braided synthetic fibre. The rope is spliced back through the hollow rope and is fixed by tension. Therefore, no additional fastening elements are necessary (Single Component Securing System). Injury free installation. (VETTER & WESSOLLY, 1994)

Band Securing System (Gurtbandsicherung): Made of woven synthetic fibres, and slung around those parts of the tree crown which are to be secured. The belt is locked with a buckle (Single Component Securing System). Injury free installation. (SINN, 1989)

Multi Component Securing System (Double Belt Securing System): Made of separate belts, with a loop on each end. Most of these products consist of a strong, outer holding belt and a second inner fastening belt, which includes a stretch element in some cases. The connecting elements (e.g. synthetic hollow ropes, steel cable) are pulled through the end loops. Injury free installation. (SCHRÖDER, 1993) 78 International Congress on The Trees of History

Multi component securing system - double belt “System Osnabrück”: broad belts, tightly fixed around the trunks (or the trunk and the branch), absorb the power occurring in mobile parts of the crown and divert it into stable tree parts. Elasticity and high breaking force are the best requirements for using synthetic fibres in crown securing systems. In this case (left ill.) all components are made of polyester fibres. The connecting element is a hollow rope, but every other suitable connecting element can be considered. Therefore the double belt securing systems provide a variety of possibilities. The stretching element in the fastening belt (right ill.) prevents the secured tree parts from growing over the belt (Ill.: KREKELAAR) In 1997 beech trees were examined in an urban forest in Osnabrück. In these trees double belt securing systems had been installed six years ago. Results of the wood-biological investigations prove that “It can be stated that even after six years, no damage to the trees resulted from the installation of the crown securing system.” (STOBBE, DUJESIEFKEN & SCHRÖDER, 2000)

Break-securing / Fall-securing Methods of crown securing should be functionally differentiated according to whether these prohibit breakage or prevent parts of trees from falling down. (SCHRÖDER, 2002; SPATZ, 2003). While break-securing aims at preventing parts of the crown in the first place whereas fall-securing is designed to prevent a part of the crown from falling down after it has come to a break, despite the attachment of a break-securing system. Fall-securing thus aims at keeping the branch up in the tree.

Installation Before installing a crown securing system one should be examined, whether pruning of the tree crown is necessary or possible. Break-securing systems should be installed at a height of 2/3 of the secured part of the crown, if possible in a triangular connection. When a single break-protection is applied, an additional ring connection should also be used in order to lessen the risk of a “twisting break”. Install at right angles from the axes of the parts of the tree crown. The natural mobility of the secured parts of the tree crowns should be taken into consideration, in order to further encouraged the adaptive growth in the now mechanically burdened parts of the tree.

Calculation The calculation of break protection systems shown below is founded upon the following securing philosophies: “Crown securing systems (break protection systems are meant here, the author) be dimensioned tree equitable if the earliest point at which they fail is the point at which the secured crown part in mechanically healthy condition would fail under the same stress” (BETHGE, MATTHECK & SCHRÖDER, 1993). Accordingly, “where a branch- or forking defect is assumed, a crown securing system (break protection system – authors note) must withstand as much stress as the corresponding structure in a mechanically healthy condition could hold” (SPATZ, 2003).

Break protections should be calculated in according with the following calculation formula:

(BETHGE, MATTHECK & SCHRÖDER, 1993) Torino, April 1st - 2 nd, 2004 79

Illustration: GEMEIN

s indicates the medium bending strength (Biegebruch) of green woods. These values B originate from the American and English literature (LAVERS, 1983; US FOREST PRODUCTS LABORATORY, 1987). They are presented in Mpa, for use in the above formula they should be converted into kp/cm² (and therefore multiplied by 10,2) in order to reach the bearing capacity tonnage (t) of crown securing systems common in arboriculture. R equals the radius of the secured part at its base (or the potential point of fracture) and h (2/3 of the total length) represents the distance between the break-securing to be applied and the base of the tree part to be secured. The following table, based on the above mentioned formula, has been developed in order to help practitioners with actual set-ups on location, with consultation and with financial estimates. It allows to rapidly and exactly working out the dimension of necessary break-securing systems (SCHRÖDER 2004). The relatively common H/D-ratio values of 20, 30 and 40 (Height [total length] / Diameter) were applied to the crown parts. As an example the table is shown with the H/D-ratio of 40. All tables can be downloaded from internet under www.demetra.net . 80 International Congress on The Trees of History

Table for the Dimension of Break-Protections

Example: H/D-Ratio:40

Precautionary advice Conditions for the application of the tables must be a generally right angle binding of the break-securing to the tree part to be secured and it’s securing in 2/3 of the total length. Because not all conditions of a tree or the influence of weather at the particular location can be taken into account, it is recommended to estimate the factors of dimension generously. This means that if in doubt select a higher collapse load than necessary! With regard to the tables, this would result in choosing a lower H/D-ratio. The calculated collapse load must still be sufficient towards the end of a crown securing system ‘s working life. Should a truncation of the particular crown part be carried out parallel to installing a break securing system, the estimation of the necessary size of the break-securing can occur according to the H/D-ratio calculated before the pruning took place. The tables may only be used if the crown parts are unable to plunge in free fall after an eventual break. Therefore, no crucial dynamical loads are expected and the calculated H/D- ratio in the actual case is available. The breaking out of heavy crown parts and the resulting acceleration of gravity is only controllable, when supplementary fall-securing systems are installed. Thus, these must be used in order to prevent fall movements of broken crown parts immediately after breaking out. However, even in this case when the height of fall merely equals the rope stretching, the securing components experience at least double the weight load of the branch which is held. A tree part which weighs 1 tonne therefore exerts a dynamic load upon the fall-securing system which corresponds to a weight of at least 2 tonnes. The dynamic load increases over proportionally through increasing the height of fall. If, for instance, this branch should fall one meter, the superlative factor may increase manifold (TESARI, MUNZINGER & MATTHECK, 2003). Torino, April 1st - 2 nd, 2004 81

Components from material with a high collapse load are especially suitable for fall-securing systems. In Germany different single- and multi component systems are available from various suppliers, whereby the load-bearing capacity differs greatly. Details and figures are available from the following addresses: Fabritz GmbH ([email protected]/www.gefa-fabritz.de) “GEFA- Schlaufenband” – multi component securing system. Connecting elements = hollow ropes and steel cable “GEFA-Gurtband mit Schnalle” – single component securing system: Libre Power sails ([email protected]/www.libre.de) “Libre-Baumhalteschlaufen” - multi component securing system Connecting elements = hollow ropes and steel cable Meyerdiercks ([email protected]/www.meyerdiercks.de) “CrownTex” – multi component securing system (double belt “System Osnabrück”). Connecting elements = hollow ropes, steel cable and any other connecting element with a sufficient load-bearing capacity. pbs-GmbH ([email protected]/www.cobranet.de) „cobra” – single component securing system ZENITH ([email protected]/www.zenith24.de) “Crown Keeper” - single component securing system

Shock absorption When break-securing systems slow down crown movements, this should happen in a “gentle” manner without a sudden stop of the secured tree parts. Otherwise this could cause injuries. However, even the securing system itself should be spared from strong dynamic loads, because strains by sudden stops can much reduce the durability of synthetic woven fabrics and roping, a phenomenon we know from seat belts. All known types of crown securing systems can be equipped with shock absorption at low extra costs, whether it is a single or multi component securing system or a connection to the tree parts through roping, band or steel cable. The shock absorption occurs simply trough the integration of elements also known in boating sport (SCHRÖDER, 2002). However, it has to be kept in mind, that shock absorbers may under certain circumstances cause a reduction of the load-bearing capacity, e. g. when these are fed into hollow ropes (TESARI, MUNZINGER & MATTHECK, 2003). If a rope of artificial fibres is used as a connecting element, an additional installation of a shock absorber might indeed not even be necessary. Due to their construction- and material- stretchability, these materials are often elastic enough to already function shock-absorbingly. An elasticity rate of 10 % is not unusual. For this reason, the usage of this type of rope, in certain cases, meets the need for a retarding and soft braking of swinging crown parts. Control

Control Materials used for the crown-securing systems age due to the influence of various factors. In the crown, the materials have to endure exposure to sunshine, frost, rain, soiling, perhaps also microorganisms, as well as mechanical strain such as the braking of vibrations, amongst other things, all affecting the efficiency of the installed crown securing system. The chemical and physical influences do not pass without leaving trace. Metals begin to corrode, synthetic fibres become brittle, splices and knots might loosen. Therefore, the efficiency of crown-securing systems must be checked regularly, according to the instructions of the manufacturer. The following checklist can be helpful when doing so (SCHRÖDER, 2002). The check-up of the securing system should be documented. For this purpose, forms have been designed which cannot be printed here, due to lack of space. However, they can be downloaded from internet under www.demetra.net . 82 International Congress on The Trees of History

Checklist for the visual control of crown securings 1. General 1.1. Is/are the installed crown securing system/s still suitable for the current safety requirements? 1.2. Is the crown securing installed expertly? 1.3. Is, as far as individually relevant, the material suitable for the bearing of continual loads? 1.4. Has the crown securing system changed position? 1.5. Is the position of the securing system situated at 2/3 of the total length of the tree part to be secured (above the base)? 1.6 Are the components ingrow-endangered? 1.7 Are the connecting elements secure? 1.8 Is the installation of further securing systems (e. g. fall securing systems) or securing levels necessary? 1.9 When was the crown securing system installed, is a replacement necessary, according to the manufacturer? 1.10 Other

2. Checking the components 2.1. Corrosion or brittleness of metal components? 2.2. Torn ropework fibres / belts? 2.3. Other visual recognizable signs of a diminishing ability of load-bearing? 2.4. Fixed screw connection of wire-rope clips when using steel cable? 2.5. Correct condition of splices or knots when using rope work? 2.6. Other

3. Checking the tree 3.1. Ingrown parts of crown securing systems? 3.2. Chafing caused by girdled components? 3.3. Chafing caused by connecting elements? 3.4. Rot? 3.5. Breaksafety of supporting tree parts guaranteed? 3.6. Other

4. Removal of deficiencies 4.1. Renewing the complete crown securing system 4.2. Adapting the crown securing system to the current situation 4.3. (Loosening) widening the securing belt, band securing or hollow rope 4.4. Installing supplementary crown securing systems e. g. fall-securing systems 4.5. Replacement of damaged parts / systems 4.6. Other

5. Tree care measures 5.1. Realisation of relieving pruning measures 5.2. Removal of ingrown components 5.3. Wound treatment 5.4. Other

Exemption from liability The tables were designed to our best knowledge their use from the original version is permitted for everyone. The writer expressively emphasises, that the control and dimensioning of crown securing systems must happen according of the judgement and specialized knowledge of the individual expert. Conditions for each individual case have to be carefully considered. Therefore, the writer is exempt from any liability for damage to persons, objects or property resulting from the use of these tables. The writer reserves the right for additions and alterations for the purpose of optimizing. Suggestions and advice are welcome.

Zusammenfassung Der Ausbruch von Kronenteilen, Zwiesel und langen Ästen, stellt die häufigste Versagensart bei Stadtbäumen dar (WILDE, 1996). Hieraus können schwerwiegende Sach- und Torino, April 1st - 2 nd, 2004 83

Personenschäden resultieren. Aber auch die betroffenen Bäume werden durch einen Ausbruch häufig irreversibel geschädigt. Ursache für dieses Versagen sind üblicherweise eingeschlossene Rinde in Zwieseln sowie Fäule und Risse in Ästen. Als Alternative zur Kappung oder Fällung solcher als bruchgefährdet erkannter Bäume wurden Kronensicherungssysteme entwickelt. Eines der ersten dieser Kronensicherungssysteme war das „Doppelgurtsystem Osnabrück”, erdacht im Grünflächenamt der Stadt Osnabrück (SCHRÖDER 1990).

Many thanks to ELENA SCHMITZ & KARIM MC LEOD for translation and SVEN DÜYFFCKE & THOMAS MAAG for assistance!

References

BETHGE, K., MATTHECK, C. & SCHRÖDER, K. (1994): Dimensionierung von Kronensicherungen ohne Windlastabschätzung. Das Gartenamt 4/1994. Patzer Verlag, Berlin – Hannover. BRELOER, H. (1996): Verkehrssicherungspflicht für Bäume aus rechtlicher und fachlicher Sicht. Bernhard Thalacker Verlag, Braunschweig, 1996 FORSCHUNGSGESELLSCHAFT LANDSCHAFTSENTWICKLUNG LANDSCHAFTSBAU E. V., BONN: ZTV-Baumpflege, Zusätzliche Technische Vertragsbedingungen und Richtlinien für Baumpflege, Ausgabe 2001 LAVERS, G. (1983): The strength properties of timber. Building Research Establishment Report, 3. edition, HMSO, London. SCHRÖDER, K. (1990): Doppelgurt für Bäume. Deutscher Gartenbau 31/1990. Verlag Eugen Ulmer, Stuttgart. SCHRÖDER, K. (1993): The double Belt System For Tree Crown Stabilization. Arboricultural Journal, volume 17, Number 4, November 1993. SCHRÖDER, K. (2002): Zur Ruckdämpfung von Kronensicherungen. LA Landschaftsarchitektur, März 2002, Thalacker Medien, Braunschweig SCHRÖDER, K. (2002): Zur Kontrolle von Kronensicherungen. LA Landschaftsarchitektur Mai 2002, Thalacker Medien, Braunschweig SCHRÖDER, K. (2002): Die Auffangsicherung, integrales Element der Kronensicherung. GrünForum.LA, September 2002, Thalacker Medien, Braunschweig. SCHRÖDER, K. (2004): Zur Dimensionierung von Kronensicherungen. GrünForum.LA, Februar 2004, Thalacker Medien, Braunschweig. SINN, G. (1989): Ein neues Kronensicherungssystem zur Verkehrssicherheit von Bäumen. Neue Landschaft 84/1989, Patzer Verlag, Hannover, Berlin SPATZ, H.- C.(2003): Kronensicherung und Auffangsicherung. Ein Kommentar zur ZTV-Baumpflege 2001, Tabelle 1 des Anhangs. Stadt und Grün 67/2003. Patzer Verlag, Berlin- Hannover. STOBBE, H., DUJESIEFKEN, D. & SCHRÖDER, K. (2000): Tree Crown Stabilization with the Double-Belt System Osnabrück; Journal of Arboriculture, Vol. 26, No.5, Sept. 2000, pp. 270-274 TESARI, I., MUNZINGER, M & MATTHECK, C. (2003): Untersuchungen zu Kronensicherungssystemen. 9. VTA - Spezialseminar „Messen und Beurteilen am Baum” 1. – 2. April 2003, Forschungszentrum Karlsruhe. US FOREST P RODUCTS L ABORATORY (1987): Wood Handbook. Wood as an engeneering material. Agricultural Handbook 72. US Department of Agriculture. VETTER, H. & WESSOLLY, L. (1994): Ein neuartiges Seilsystem zur Sicherung von Baumkronen. Neue Landschaft 1/94. Patzer Verlag, Berlin – Hannover. WILDEM. (1996): Baumkontrollen im Rahmen der Verkehrssicherungspflicht als Aufgabe kommunaler Verwaltungen. Schriftenreihe des Fachbereichs Landschaftsarchitektur, Heft 13, Fachhochschule Osnabrück, 1996 84 International Congress on The Trees of History

COMPRESSED AIR DIGGING DEVICE AS A TOOL FOR THE INVESTIGATION OF ROOT SYSTEMS. A CASE HISTORY A. Pestalozza, G. Passola, F. Ferrari

1. Introduction When considering trees in built environments, as cities or roadways, the interactions among trees building and utilities are critical. Trees are strongly affected by development; construction influences the space available above and below ground as well the surrounding microclimate. In the other hand trees may also directly impact constructions an infrastructures built near them. Trees may develop against utility lines or against buildings or grow into sewers and other drainage pipes. Tree roots are often damaged during building maintenance operation or construction projects, particularly during trenches excavation for underground installation as pipelines, phone, electrical cables etc. Conventional soil scrapers are heavy machinery, such as excavators or backhoes, which heavily impacted the root systems during the soil removal and the trench creation. Soil excavation should be necessary during the above mentioned situations or in addition for tree root inspection as well as for soil decompactation. The root inspection performed by soil excavation is a very useful practice, basically for city trees, when it is necessary to evaluate Figure 1 Roots attacking a wall the root system conditions in order to have information about tree stability. As we know it is very difficult to assess root damages by means traditional VTA techniques even if supported by instrumental analysis.

2. How to inspect and manage root system Different alternative soil excavation methods exist that preserve tree roots. These methods include manual, hydraulic and pneumatic systems. The manual soil excavation system is performed by hand tools such as shovels, weeding hoe, small rakes and brushes, to remove soil from the root zone. The benefit of this method is that the tool cost is very low and the workers training too. In the other hand, from the financial point of view, the working time is maximize and from the qualitative point of view only the large roots are preserved while smaller diameter roots are often broken. The hydraulic soil excavation system has been recently refined (Gross, 1995) by using water to remove soil from the root surface. This technique is the most powerful and therefore the fastest of the alternative soil excavation methods. There are several drawbacks in that method as high water consumption, slurry production (to be drained) and fertile soil substitution. The pneumatic system produce a series of small explosions away from non porous objects, such as underground utilities or plant roots, the air flow impact is quite soft against these bodies because the excavated soil is transformed into scrapes or small fragments so this technique protects tree roots, including small diameter and fine roots. Additional benefits of the pneumatic soil excavation method is the unlimited air supply, relatively minimal clean up and reusability of the excavate. The pneumatic soil excavation system can also be used in combination along with conventional machinery. First the soil among the roots is excavated pneumatically then a conventional excavator can be used below the root level to increase the trench depth and the production rate, avoiding root Figure 2 - Two person crew do about 70 m2/day for about 0.2-0.25 m depht damages. Torino, April 1st - 2 nd, 2004 85

3. Case history 3.1 VTA in Caserta Botanical Garden: Un example of root inspection by AS system In April 2003 has been made a root inspection of a great Cupressus macrocarpa situated inside the Caserta Botanical Garden. This tree was affected by a large internal cavity in the stem, detected by Resistograph system, but no other defect was found. The inspection was made by Air-Spade tools, using a big compressor with 4500 l/h air flow and pressure about 7 bar. This tool was chosen in order to avoid damage at the root system, and for his easy use and efficacy. The various step of the intervention have been: - To cut very short the grass, in order to simplify the excavation. - Preparation of the yard. Is very important to bound the yard with special tissue, to avoid accidental damage to person or things, caused by chips or flying gravel. - Digging. Depending of the soil density, moisture and compactness, is possible to remove different quantity of material. The inspection of the Cupressus roots showed us something unexpected, in fact there was a large injury and cavity in the main and secondary roots. All the wounds was situated about 1,5 meter from the stem, and they was probably caused by a deep ploughing made during the park maintenance after a long time of disuse. The biggest hurt in the root showed in the picture has probably advanced in the wood till the stem, causing the big hollow detected before. Inspection allows us to understand the cause of the internal defect, and show how is dangerous to plough or excavate next the tree. Besides this work will help the tree in the future growing, because Figure 3 - Serious damages under the soil has been improved adding lapillus and a lot of soil level nutritive elements.

3.2 Yard operation around root system: how to dig, how to find, deviate and properly cut root branches The air excavation is a hand held tool that produces a “laser-like” jet of air moving at approximately 2000 km/h, i.e. twice the speed of sound. The tool consists of a manually operated, spring return, on / off valve, a rigid barrel, and a supersonic nozzle. It is to be connected to a standard industrial air compressor capable of producing the above stated flow at the above stated pressure. Air excavation system is really easy and efficacious digging system, and in order to operate is enough to follow some simple rules. Is basic to use the right compressor, in order to have the necessary powerful. For the standard nozzle, it is recommended that this tool would be used with a compressor rated at a minimum 4.6 m3/min, and 6.4 bar . If alternate nozzles are purchased, the compressor must be of sufficient pressure capacity, 6.4 bar, and have a flow at least equivalent to 110% of the nozzle’s m3/min rating. During the digging operation, the operator have always to wear appropriate protective work clothing and equipment. Cut and puncture resistant gloves, approved safely eye glasses with side shields and / or face protection, and approved hearing protective earplugs or earmuffs are recommended. In extremely dusty conditions, operator should wear approved respiratory protection. Figure 4 – Transplanting operation (G. Passola) For normal excavation, the best performance is achieved by holding the nozzle roughly perpendicular to the ground Depending on the soil type, the air-system is best moved along the surface to be excavated at a rate on the order of one to two foot per second (0.3 to 0.6 m/sec). Except in very hard and compacted clays, dwelling on the same spot tends to reduce the rate at which material is excavated and can increase the amount of material blown away from the excavation site. When boring a narrow hole in the soil, the tendency to expose the operator to material blown back directly out of the hole is increased. The air system for general excavation is supplied with an auxiliary dirt shield that serves to confine any excavated 86 International Congress on The Trees of History material that may become airborne from leaving the general area of the nozzle. If soil is encountered that is difficult to dig, try adding some water to soften. Repeat until the desired results are obtained. The air excavation is essential in every kind of work side by side the tree. Is particularly indicated in root collar excavation, radial trenching bare rooting, transplanting, and moving large tree, work root structure analysis, new construction and landscape architecture, installing irrigation lines and locating utilities. A correct digging permits to follow all the main root, and deviate it, in order to avoid all the possible cut. The root bending, have to be made for little angle, because the roots are not too flexible and risk to have internal crack. If the cuts are inevitable we can choose where and how to cut, reducing the impact in the big tree. During the root pruning is essential make little and careful cut, using un apposite saw. If the analysis, and the digging are made in a hot and sunny days, we have to cover all the roots using a wet jute o tissue, to preserve vitality condition.

3.3 Inspection and un-compaction Inspection activity, quite often has a good feedback for the tree Air excavation permits to have complete view over the roots system, showing all the hide defects. For this reason is considered a very good way to assess the root system conditions. Air digging has the double purpose to analyze roots and to improve the soil features. First of all, excavation reduce the soil compacting, and increase the underground oxygen next the roots. The soil could be improved too with the addition of nutritive elements, humus, micro elements, mycorrhiza, lapis, acc The choice of the elements depending of the health status of the tree, and the soil condition. Our experience show that trees enjoy the soil improvement, and the effect are manifested already the first year after application. Would be better to repeat the treatment the following years, in order to increase the success likelihood.

4. Conclusions 4.1 Air excavation and removal soil system is essential for the tree assessment requiring a root inspection

Air excavation, and every kind of removal soil system solve just the inspection problems. Is necessary in fact to have the necessary experience to evaluate the soil and the root conditions, in order to advance advice about tree and root stability. Right wood inspection device, as Resistograph or sonic instrument are always essential to evaluate wood condition and defect detection. But roots strength could be detected only with dynamic system, that check the tree behavior submitted to natural o artificial stress.

4.2 It gives a good contribute to clarify root geometry and conservation Air excavation as we have demonstrated permits to have a complete view of the roots geometry and conservation. The health wood condition and the smallest root twigs vigour could be checked. The complete or partial absence of root twigs indicate a poorness of nutritive elements or oxygen in the soil, that is possible to improve thanks good soil and nutritive elements add. The air excavation overwork the soil macro porosity, destroying all the compact earth. For that reason the roots and the pipes lacking of macro porosity are not destroyed.

4.3 It is very handily efficient and financially cheap Air excavation for its efficiency and easy use is considered really advantageous. This system need just un adequate compressor and the air tools indeed. No long experience or complex instrument are request. In other world doesn’t exist, at the moment, other way to excavate so cheap, complete and suitable for this work. Torino, April 1st - 2 nd, 2004 87

Bibliography The landscape below ground (D. Neely, G. Watson) Trees & building sites (D. Neely, G. Watson) Supersonic Air Jets Preserve Tree Roots in Underground Pipeline Installation (R. Gross, M. Julene) Vita da alberi a Milano (ACER 4/2001 A. Pestalozza; A. Pellegatta) Air Excavation to improve Tree Health (T. Smiley Tree care Industry) Posters 90 International Congress on the Trees of History Torino, April 1st - 2 nd, 2004 91

MONUMENT TREES AS WITNESSES OF LOCAL POTENTIAL VEGETATION AND LANDSCAPE EVOLUTION G. Barbera1, S. Pasta2 and T. La Mantia1 1 Dipartimento di Colture Arboree, Facoltà di Agraria - Palermo 2 Palermo

Introduction During the last years several researches have been carried out on the Italian monumental trees; more recently, more attention has been paid on Sicilian ones (Schicchi and Raimondo, 1999). Monument trees are getting more and more important for the key role they play as witnesses of both local natural history and human activity. Besides, through modern tools, such as Pressler increment borer, monument tress can be exploited also to obtain accurate data on climate and atmosphere evolution during the last centuries. The study case of the monument trees of the Favorita Park is here discussed. This Park, between Monte Pellegrino and the city of Palermo, is about 300 Ha wide and belongs to the “B” zone of Monte Pellegrino Nature Preserve, instituted by Sicilian Autonomous Regional Government in 1995. This Park gives hospitality to some scattered relics of semi-natural vegetation, while other surfaces are still occupied by .crops and formal gardens deriving from the first decades of the XIXth century.

Study area Some information on the environmental characteristics, the history and the land use evolution of the Favorita Park are useful for a better understanding of the value of the monumental trees which live in it. Palermo Plane is characterized by a typical Mediterranean climate and a very good soil quality; thus, no surprise that the area was known as “ü êÞðïò” (= the Garden) by Greeks (Rocci, 1980), was called “Geonard” (= the Paradise on Earth) by Arabs (Pirrone et al., 1990), and, since the XVIth century, was named “Conca d’Oro” (= the Golden Valley). The local original climax probably was a mixed forest dominated by the evergreen holm oak (Quercus ilex L.) and some deciduous thermophilous oaks such as Quercus virgiliana (Ten.) Ten. and Q. amplifolia Guss (Fig.1). Centuries of frequent and intense human impact (cutting, wildfires, grazing, cultivation and, more recently, pollution, urbanisation, afforestation and alien plants introduction) totally erased the primary vegetation in the whole territory. Favorita Park is someway an exception within this sad picture. The Park history is strictly linked to the Christmas day of 1798, when King Ferdinand IV of Bourbon escaped from Naples to Palermo. Already in the first months of the following year, through a royal edit, he bought the goods of many local noble families (Airoldi, Salerno, Pietratagliata, Niscemi, Vannucci, Malvagna, Lombardo, etc.). In a few months, the “Real tenuta della Favorita” was ready, so that the king could enjoy his favourite hobbies: hunting and agriculture. Little woods, dominated by plants typical to the Mediterranean evergreen maquis, were planted; they were interrupted by numerous hunting lanes, alle statues and doric columns: “A certe determinate distanze s’incontrano delle deliziose colline che incantano lo sguardo colle mirabili e variate scene della natura Si osserva in una di queste un ombroso e solitario boschetto, nel di cui centro sorge la statua di marmo bianco della cacciatrice Diana.” (Palermo, 1816). At the same time, some experimental fields were realized, such as orchards and vineyards, whose irrigation system are easy to recognize still nowadays: “Si sono da S.[ua] M.[aestà] tentate in questi terreni diverse speculazioni ed esperimenti al miglioramento dell’agricoltura, applicandovi le teorie dei moderni e più accreditati autori, i quali su queste agrarie materie hanno dottamente scritto e la vegetazione delle piante, delle frutta, e di altre produzioni, ne ha riportato un utile e felice successo.” (Palermo, 1816). Pasca (1868) writes that “dalla Real Favorita venne l’arancio-mandarino di cui la pianta madre primitiva esiste tuttora sin dal 1810, e oggi se ne fa commercio”. As well documented (La Mantia, in press), the local crops were the same of the Piana dei Colli (localized between the ancient city and the northern villages of Mondello and Sferracavallo). Olive groves were the most widespread culture, together with almond (Amygdalus communis), sumac (Rhus coriaria) and prickle pear (Opuntia ficus-indica) cultivations, while mulberries (Morus alba and M. nigra), carobs (Ceratonia siliqua), wallnuts (Juglans regia), figs (Ficus carica) Mediterranean hackberry (Celtis australis) and annual crops were rare. Between 1856 and 1922 the area experienced some relevant changes in land use patterns: Arundo donax, Rhus coriaria and Fraxinus ornus cultivation and of most part of the annual crops, once characterising the local agricultural landscape, totally disappeared, while a powerful spreading of Citrus orchards (from 12 to 31 Ha), led in the following years to a local triumph of citrus cultivation (Fig.2). 92 International Congress on the Trees of History

Investigation methodology Our field survey, carried out within the Favorita Park, aimed to individuate the most noteworthy trees. This census was achieved by using a schedule already available in literature but modified. These schedules (see annexes 1-2) contain the following data: Identity (binomial classification, family and vernacular name); Localization (municipality, name of the locality, way of access); Ownership (public or private); Environmental characteristics of the stand (altitude, exposition, inclination and substrate); Major morphological (general description, maximum circumference at 1,30 m, overall plant height, crown width, estimated age) and biological characteristics (vegetative and phytosanitary state); Threats; Proposed interventions. A particular attention was payed to verify both the vegetative and phytosanitary state and the proposed interventions. In case of lack of dendrochronological relieves, the age of the plants has been estimated.

Results Notwithstanding the lack of a standard definition of what “monument trees” actually are, there is no doubt that within the Favorita Park grow several noteworthy plants.Most of them derive from the XVIII century shaping and designing of the park itself, while only in some cases they seem to be native plants survived to man impact and, thus, they are localized in the most undisturbed areas. During this preliminary field survey 29 monument trees have been encountered: 13 Quercus, 6 Cupressus, 3 Pinus, 2 Schinus, 2 Celtis, 1 Olea, 1 Ceratonia, 1 Morus. These trees grow within the wood, hedges, or as relics within the cultivated areas. Monument trees play a major role in defining the local potential vegetation. For example, the huge individual of Quercus virgiliana was probably already there before Bourbons’ interventions, as its estimated age is of about 300 years. Up to the middle of the XXth century, another large white oak grew not far from this one, and its acorns were toasted by local farmers to make a surrogate of coffee. The presence of this white oak confirms the current hypotheses on the potential vegetation of the Park and of the whole Conca d’Oro (Brullo & Marcenò, 1985; AA.VV., 1996; Gianguzzi et al., 1996). Besides, this plant probably is the last - and the only - native deciduous oak detected in the whole Conca d’Oro since when Gussone (1842- 1845), more than 150 years ago, noticed Q. virgiliana elsewhere in the Plane, near “Roccazzo”. Still nowadays Favorita Park maintains many evidences of the transformations it underwent due to the intervention planned by King Ferdinand IV: on Monte Pellegrino foots still survive the last examples of dry orchards, with olive and almond groves. Within these orchards, it is still possible to find some very old olive trees (Olea europaea), carobs (Ceratonia siliqua) and white mulberries (Morus alba). Most part of the censed monument trees (12 holm oaks, 6 cypresses, 3 stone pine, 3 Peruvian peppertree and 2 Mediterranean hackberry) grow within the little Quercus ilex-dominated woods realized by Bourbons or along the hedges (Fig.3). The artificial origin of the little holm-oak woods is revealed by the geometric patterns of their design and shape; nevertheless, in those scattered areas of artificial forest, which could be classified as old coppices, it is still possible to “glimpse” the primary vegetation of the Park and, more generally, that of the whole Conca d’Oro. In particular, the biggest holm oak trees give an image of high wilderness.

Conclusions Favorita Park’s monumental trees shall be considered as witnesses of all the different land use typologies once present in the area and allow us to make some hypotheses on the local potential vegetation and on the landscape evolution as well. This census shall be considered as a starting point for a more accurate investigation on the tree heritage of the Favorita Park. The active safeguard of these plants (e.g. through germplasm gathering, conservation and diffusion) is very important; besides, many of these plants need a periodic monitoring and some dendrochirurgical cares, as they are weakened due to their age .Future investigations should offer further surprises. For example, the huge Quercus virgiliana (Ten.) Ten. was never noticed before, although if careful investigations have been recently carried out on the flora (Raimondo, 1992), the vegetation (Gianguzzi et al., 1996) and the land use of the Favorita Park (La Mantia, in press).Another point to clarify is what monument trees really rare: this concept seems particularly ambiguous if we consider the fruit orchards. Some mandarin, for example, deriving from the orchard realized at the beginning of XXth century shall be considered as monuments, indeed, as they were explanted from Citrus orchards of Palermo city when they were already adults, between 1950 and 1965. Finally, Favorita Park gives hospitality to several fruit trees, such as a very old apple tree (similar to “limoncella”, a very rare local cultivar). Thus, the project to transform the actual Torino, April 1st - 2 nd, 2004 93 agricultural landscape of the Favorita Park to restore the XVIII century design worths a careful re-consideration.

References AA.VV., 1996 - Carta della vegetazione potenziale, f.-t.- In: Regione Siciliana, Assessorato Beni Culturali e Ambientali e Pubblica Istruzione (a cura di), “Linee-Guida del Piano Territoriale Paesistico Regionale”. Brullo S., Marcenò C., 1985 - Contributo alla conoscenza della classe Quercetea ilicis in Sicilia.- Not. Fitosoc., 19 (1) [1984]: 183-229. Gianguzzi L., Ilardi V., Raimondo F.M., 1996 - La vegetazione del promontorio di Monte Pellegrino (Palermo).- Quad. Bot. ambientale appl., 4 [1993]: 79-137. Gussone G., 1842-1845 - Florae Siculae Synopsis exhibens plantas vasculares in Sicilia insulisque adjacentibus hucusque detectas secundum systema Linnaeanum dispositas. Neapoli, Typ. Tramater, 3 voll. La Mantia T., In press – Ecologia e agricoltura nel parco della Favorita. Comune di Palermo Palermo G., 1816 - Guida Istruttiva - giro della mura, delle porte e delle loro adiacenze- Palermo. Pirrone G., Buffa M., Mauro E., Sessa E., 1990 - Palermo, detto Paradiso di Sicilia (Ville e Giardini, XII-XX secolo).- Centro Studi di Storia e Arte dei Giardini, Palermo, 285 + i pp. Rackham O., 1992 - Trees and woodland in the history and archaeology of the landscape: 249- 263. In: Bernardi M. (Ed.), “Archeologia del paesaggio”, IV Ciclo di lezioni sulla ricerca applicata in Archeologia (Certosa di Pontignano, Siena, 14-26 gennaio 1991), C.N.R. - Univ. Siena. Ed. All’insegna del Giglio, Firenze. Raimondo F.M. (ed.), 1992 - Studio e catalogazione della flora, della vegetazione e delle emergenze botaniche ed ambientali del Monte Pellegrino (Palermo).- Comune di Palermo, Palermo, Assessorato Parchi, Verde ed Arredo Urbano, 222 pp. + carta (scala 1:8.000). Rocci L., 1980 - Vocabolario Greco-Italiano. Soc. Ed. Dante Alighieri, Firenze. Schicchi R., Raimondo F.M., 1999 - Contributo alla conoscenza degli alberi monumentali delle Madonie (Sicilia centro-settentrionale).- Naturalista sicil., s. IV, XXIII (1-2): 229-314.

Tabb. 1-2 – Schedules examples (Fig.3) 94 International Congress on the Trees of History

Fig.1 – The monumental Quercus virgiliana living at “Parco della Favorita” Torino, April 1st - 2 nd, 2004 95

Fig.2 – The last examples of dry orchard in Conca d’Oro are found at “Parco della Favorita”. Monumental olive trees still live in the area (right plate); in many cases some individuals pre-existing to citrus orchard plantation survive (left plate)

Fig.3 – Hercules column surronded by monumental cypresses in 1930’ and present-day pictures 96 International Congress on the Trees of History

MOLECULAR TOOLS FOR IDENTIFICATION OF DECAY FUNGI DIRECTLY FROM WOOD **S. Bergemann, *C. Billi, **M. Garbelotto, *P. Gonthier, *F. Guglielmo, *G. Nicolotti, **J. Tse * DI.VA.P.R.A. Plant Pathology – University of Torino, Grugliasco (TO), Italy ** Dept. ESPM - University of California at Berkeley – California , USA

Summary A PCR-based technique for the identification directly from wood of some of the most important decay fungi of standing trees is developed in this study. Taxon-specific Polymerase Chain Reaction (PCR) primers were designed in the 25S region of the ribosomal DNA for several taxa of Basidiomycetes belonging to the following genera: Armillaria, Ganoderma, Hericium, Inonotus, Laetiporus, Omphalotus, Phellinus, Pleurotus, and Stereum. When tested on colonized wood blocks primers selectively amplified the target species. No cross-reaction occurred against DNA of closely related genus or species. This procedure serves to be a promising tool for the rapid diagnosis and identification of decay fungi.

Introduction Wood decay of trees represents a distinct problem not only for horticulturists and arborists, but also for veteran tree managers. Problems related to decay in trees range from unappealing aesthetics to hazardous situations. While only a few decay fungi are directly responsible for tree mortality, the loss of mechanical strength caused by these organisms is inherently linked to tree windthrows or limb failures. The detection of hazardous trees is currently based on Visual Tree Assessment (VTA) (Mattheck and Breloer, 1994), or on related approaches such as Static Integrated Assessment (SIA) and Static Integrated Methods (SIM) (Wessolly, 1995). The basis of VTA is a visual scoring of obvious symptoms (e.g. emerging wood decay, branch flagging, reduced vigor, etc.) and signs (e.g. ring bulge, cracks, ribs, etc.) known to be connected to significant decay within the tree. In order for signs and symptoms of decay to be visible, the decay process must be in a relatively advanced stage. Although good training and VTA standardization efforts have partially overcome the problems due to the subjectivity of the observer, VTA still allows for a large error in the evaluation process. Various and different technologies have been developed to assess extent of decay within a tree both in invasive (e.g. resistograph, portable drill), and in non-invasive ways (Nicolotti et al., 2003). Some of them (e.g. resistograph) are already included in VTA protocols to analyze suspected trees. These approaches are constantly being improved, but they are in general unable to effectively identify the decay agent in its first stages. This drawback, while significant for all types of decay, becomes more problematic when the decay agent may be extremely active and decay may progress extremely rapidly from an undetectable stage to an hazard stage. Alternatively, this limitation may become serious for types of white rot decay in which loss of mechanical strength is progressive but extended over relatively long periods of time. In the case of monumental trees, veteran trees, or trees with “historical” importance, this drawback prevents a timely employment of treatments such as extensive pruning, harnessing, or filling and sealing of the decay cavity. Fruit bodies differentiation frequently occurs late, when decay is already at an advanced stage, or often it does not occur at all. That represents a serious problem because, unless fruiting bodies are visible, it is extremely difficult to diagnose the fungal species responsible for the decay. Knowledge of the organism(s) involved is pivotal in understanding how fast the decay process is going to develop, which part of the trees are likely to be involved, and what is the potential of spread from one tree to neighboring trees. These information may be of help for prognosis. Diagnostic methods based upon the detection and the analyses of fungal DNAs, particularly by Polymerase Chain Reaction (PCR) have been successfully employed in several fields of plant pathology. However, methods allowing for the distinction of the most important decay fungi directly from wood are not available yet. The success of these methods is largely dependent on whether sufficient pure fungal DNA is extracted from wood or not (Jasalavich et al., 2000; Gonthier et al., 2003; Sicoli et al., 2003). Several technical problems connected with the complex chemistry of the wood may affect DNA extraction. The goals of the present study were: i) to develop and test a protocol allowing for successful fungal DNA extraction and PCR amplification from wood, and ii) to design and test molecular markers to distinguish some of the most dangerous and widespread decay agents. Torino, April 1st - 2 nd, 2004 97

Material and Methods Samples used for fungal DNA extraction from wood Attempts of fungal DNA extraction were carried out on thirty Quercus agrifolia and Q. kellogii wood samples putatively colonized by fungi. Samples, of about 6x4x2 cm, originated from different locations in California (USA). To test the extraction of fungal DNA also from coniferous wood, 10 putatively colonized Pinus cembra samples, originated from Aosta Valley (Italy), were included in the experiment. Wood samples were stored at –80°C.

DNA extraction from wood for fungal Internal Transcribed Spacer (ITS) amplification Slivers, of about 1x1x2 mm, obtained from the wood samples were lyophilized for 36 hours in 2 ml Eppendorf tubes. Three sterile glass beads were added to each tube. The tubes were precooled in liquid nitrogen and then the material was pulverized in an amalgamator at 6.5 m/sec for 25 sec. The frozen powder was immediately transferred at – 80°C before DNA extraction. The fungal DNA was extracted directly from pulverized wood using the QIAamp DNA Stool Mini KitTM(Qiagen) according to the manufacturer’s instructions. A 1:100 dilution of extracted DNA in PCR water was used for amplifications. The success of fungal DNA extraction from wood was verified using ITS primers specifically designed for fungi, named ITS-1F (5'-CTTGGTCATTTAGAGGAAGTAA-3') and ITS-4 (5'- TCCTCCGCTTATTGCTATGC-3'). Amplifications were carried in 25 ìl volume containing 50mM MgCl2 (Invitrogen), 10X PCR buffer (Invitrogen), 20mM dNTPs (Invitrogen), 5U/ µl Platinum® Taq DNA Polymerase (Invitrogen). Reactions were conducted in a Thermal cycler programmed for an initial 2 min. denaturation at 94°C followed by 32 cycles of denaturation (1 min. at 94°C), annealing (1 min. at 55°C), and extension (1 min. at 72°C). A final extension of 10 min. at 72°C followed the 32 cycles. Amplification products were analyzed by electrophoresis on agarose gel (1.5%) in 0.5X TBE (Tris-Borate-EDTA) for 1 h and 20 min. at 70 volts. Products were stained in ethidium bromide and visualized under ultraviolet lamp.

Isolates and DNA sequences used for taxon-specific primer design Isolates belonging to 36 species included in 9 genera of wood decay basidiomycetes were used to develop taxon-specific primers. Isolates belonged to Armillaria, Ganoderma, Hericium, Inonotus, Laetiporus, Omphalotus, Phellinus, Pleurotus, and Stereum. The identification of fungi was performed on the basis of the macroscopic and microscopic features of their fruiting bodies, and pure cultures were obtained from the context of basidiocarps. In addition to the isolates, all the sequences published on National Center for Biotechnology Information (NCBI) Genbank and referring to each taxon of interest were also used for taxon-specific primer design. The number of isolates for each species and the closely related species used as outgroups are shown in Table 1.

Table 1. – Number of isolates for each species and corresponding outgroup taxa used for taxon-specific primer design 98 International Congress on the Trees of History

Design of taxon-specific primers The 25S region of the nuclear Large subunit RNA (nLSU) was selected for the purpose of designing generic-specific primers, and species-specific primers for Phellinus gilvus. Species- specific primers were developed for Inonotus andersonii and I. dryadeus both on 25 S and ITS. Few hyphaes from aerial mycelium were collected by pipette tips from three day-old pure cultures grown on Malt Extract Agar (MEA; 20 g agar, 20 g glucose, 20 g malt extract, 2 g peptone, 1 l deionized water), and placed into 100µl of sterile water in Eppendorf tubes. The tubes were freezed on dry ice and then thawed quickly by placing them at 75°C in a dry heat block. After thawing, the tubes were vortexed for 1 min. and spinned in a micro centrifuge at top speed for 5 sec. Cycles of freezing and thawing were repeated for three times. The tubes were then placed in a 75°C dry heat block for 15 min., and finally spinned for 5 min. at maximum speed. Direct PCR was performed on the hyphal suspension without any dilutions. Fungal DNA was also extracted from the entire culture using CTAB and phenol/ chloroform protocol, as described by Gardes and Bruns (1993). A 1:1000 dilution of extracted DNA in PCR water was used for amplifications. The 25S region of the nuclear ribosomal DNA was amplified using the universal primers CTB6 (5’-GCATATCAATAAGCGGAGG-3’) and TW13 (5’-GGTCCGTGTTTCAAGACG-3’). PCR-amplified products were electrophoresed on a 1.5% agarose gel as described above. Amplicons were sequenced using an ABI 3100 (Applied Biosystems, California) automatic sequencer. Sequences assembly and manual refinement of alignments were carried out using the Sequencer 4.1 program. The sequences from each taxon were aligned with sequences of closely related groups (outgroups) in order to ensure the specificity for the target organism. A highly conserved sequence in the 25S DNAwas used to design a forward (5’→3’) primer, that we named 25S-F. Taxon-specific primers were designed as reverse (3’→5’). The same approach was used to design species-specific primers for Phellinus and Inonotus. The amplification of ITS was performed using the primer combination ITS-1F and ITS-4. The PCR conditions were as described above, except for the annealing temperature of the reaction that was lowered to 53°C. The ITS3 primer (5’-GCATCGATGAAGAACGCAGC-3’) was selected as forward primer. Primer design was performed with PRIMER 3 software in order to maximize its efficiency.

Taxon-specific primer testing The specificity of primer pairs was tested on DNA extracted from pure fungal cultures. Primers were finally tested on fungal DNA extracted from 60 wood samples (1x1x2 mm) of Quercus agrifolia and Q. kellogii colonized by known wood decay agents. Fungal DNA was extracted directly from wood as described above. PCR conditions were separately optimized for each primer combination. Amplified DNA was visualized and its size determined by standard DNA electrophoresis on agarose gel. In order to confirm the specificity of the primers a subsample of 25% of PCR products were also sequenced. The ABI 3100 genetic analyzer was used for an accurate fragment size analysis to verify the specificity (GeneScan technique) of primers (not shown).

Results The DNA extraction using the QIAamp DNA Stool Mini KitTM allowed the amplification of putative fungal DNA from all samples included in the experiment. The ITS amplified region of unknown fungi resulted in PCR products of various length (from 750 bp to 800 bp, approximately) (Fig.1). The CTAB phenol/chloroform extraction generated good amplifications from pure cultures.

Fig. 1 – ITS amplification of fungal DNA extracted from 10 wood samples. ITS was amplified with the primer combination ITS 4-ITS 1F Torino, April 1st - 2 nd, 2004 99

Sequence alignment showed a region in common for all taxa within the 25S. Such DNA region is about 30 bp long, and its location within the nLSU is shown in Fig 2.

Fig 2 – The black box indicates the region (about 30 bp long) in common for all taxa within the Ctb6-Tw13 region of the nLSU. This 30 nucleotide (nt) sequence was used to design the the 25S-F primer

The 25S-F primer is 18 nt long. The sizes of taxon specific amplicons generated through PCR are listed in Table 2.

Table 2 –Length of the amplicons (base pairs) originated through PCR in the nLSU and ITS

All taxon specific primers designed on nLSU allowed selective amplification of pure cultures with no cross-reactivity with other taxa (Fig. 3)

Fig 3. – Amplification product obtained with the taxon-specif primers 25S-F and Phellinus gilvus reverse: lanes 1 to 14

Species-specific primers designed in the ITS region showed cross-reactivity with other species while tested on pure cultures (Fig. 4). This was particularly true for Inonotus andersonii and I. dryadeus with Ganoderma, Stereum, and several Phellinus species. 100 International Congress on the Trees of History

Fig 4 – Amplification product obtained with the specific primer set ITS 3 (forward) and Inonotus dryadeus reverse on pure cultures of different species. The bands show unspecific amplification. I. dryadeus reverse primers cross-reacted with: Ganoderma (lane 1), Stereum (lane 2) and several Phellinus species (lanes 3 to 5). Lane 6 shows the amplification of Inonotus dryadeus DNA

While tested on the 60 wood block samples, taxon specific primers allowed the detection of 47 fungi. Taxon specific primers allowed the amplification of expected fungal taxa in the 77% of cases (Table 3). In 5 samples (8%), expected fungi were not detected with taxon specific primers. In 9 wood samples (15%), more taxa than the only one species expected were detected. Phellinus was the most frequently observed genera.

Table 3. – Extract from observed versus expected taxa in primer testing on 60 wood samples

The basidiomycetes considered in this study are responsible for most of tree failures reported in the temperate areas of the world. Although some of the above listed genera include more than one species, the biology of congeneric species is quite similar, and differences are often in host specificity. The QIAamp DNA Stool Mini KitTM is a method that simplifies isolation of DNA from stool with a fast spin-column procedure, no phenol and chloroform are required. This procedure allows for the amplification both from Quercus and from Pinus. These two hosts are known to be reach in polysaccharides, proteins and phenols, inhibitors of the PCR reaction (Khanuja et al.1999). Furthermore field samples may often contain contaminants, or compounds causing DNA degradation. The kit offers a fast and easy purification of the total DNA recovered from field samples, even from recalcitrant wood. Specific reverse primers for genera and for species were successfully developed in the 25S region of the ribosomal DNA for Armillaria, Ganoderma, Hericium, Laetiporus, Omphalotus, Torino, April 1st - 2 nd, 2004 101

Pleurotus, Stereum, Phellius gilvus, Inonotus andersonii, Inonotus dryadeus. Use of nuclear ribosomal regions is recommended as they are present in many copies within the genome, and allow for detection of a minute amounts of the target DNA. This is a region that is frequently conserved within genera and variable between genera. Species specific primers designed in the ITS showed cross-reactivity while used on pure cultures and did not work when tested on wood samples. The ITS generally shows an high level of both interspecific and intraspecific polymorphism (Wagner and Fischer, 2002), and it does not appear suitable the goals of this research. The results reported here indicate that it is possible to identify the pathogens directly from wood without the step of culturing the fungus. Fruiting bodies of the fungus can provide material for its identification; however they are very ephemeral and do not necessarily occur at the first stage of the wood colonization. Other molecular techniques for the detection of targeted organisms, as RFLP, need longer procedure, restriction profiles are often difficult to read and they do not allow for a secure identifications (Fischer, 1996; Jasalavich et al., 2000). We developed a rapid, reliable and sensitive method to detect specific fungi in the wood. One of the main advantages of this approach is that the diagnostic approach can be highly specific, meaning that it can be designed to target all known organisms deemed responsible for important decay effects on trees of relevance to the urban landscape and to ornamental arboriculture. Although at present the identification of fungi with the technique described in this paper still requires 2 days, the optimization of reactions with multiplex PCR approaches will allow faster detections, providing a reliable tool for routine inspections of suspected trees.

References Fischer M., 1996. Molecular and microscopical studies in the Phellinus pini group. Mycologia 88, 230-238. Gardes M., Bruns T.D. 1993. ITS primers with enhanced specificity for basidiomycetes - application to the identification of mycorrhizae and rusts. Molecular Ecology 2, 113–118. Gonthier P., Garbelotto M., Nicolotti G. 2003. Swiss stone pine trees and spruce stumps represent an important habitat for Heterobasidion spp. in subalpine forests. Forest Pathology 33, 191-203. Jasalavich C.A., Ostrofsky A., Jellison J, 2000. Detection and identification of decay fungi in spruce wood by restriction fragment length polymorphism analysis of amplified genes encoding rRNA. Applied and Environmental Microbiology 66:4725-4734. Khanuja S. P. S., Shasany A. K., Darokar M. P., Kumar S.1999 Rapid Isolation of DNA from Dry and Fresh Samples of Plants Producing Large Amounts of Secondary Metabolites and Essential Oils. Plant Molecular Biology Reporter 17, 1-7. Mattheck C., Breloer H., 1994. Field guide to VTA (Visual Tree Assessment). Arboricultural Journal 18, 1-23. Nicolotti G., Socco L.V., Martinis R., Godio A., Sambuelli L., 2003. Application and comparison of three tomographic techniques for detection of decay in trees. Journal of Arboriculture 29, 66-78. Ouis D 1999 Wood Science and Techology. 33 151-184. Vibrational and Acoustical Experiments on Logs of Spruce. Sicoli G., Fatheti J., Stenlid J. 2003. Development of species-specific PCR primers on rDNA for the identification of European Armillaria species. Forest Pathology 33, 287-297. Wagner T, Fischer M. 2002. Proceedings towards a natural classification of the worldwide taxa Phellinus s.l. and Inonotus s.l., and phylogenetic relationships of allied genera. Mycologia 94, 998- 1016. Wessolly L., 1995. The practitioner’s method of diagnosis. Stadt und Gruen 8, 570-573. 102 International Congress on the Trees of History

THE HISTORIC CYPRESSES OF BOLGHERI: RESTORATION AND ENHANCEMENT OF A HERITAGE OF EUROPE R. Danti1, P. Raddi1, A. Panconesi1, R. Serra2, M. Tognotti2 1CNR, Istituto per la Protezione delle Piante, Area della Ricerca, Sesto Fiorentino - Italy 2Provincial Administration of Livorno - Italy

The symbolic role of cypress at Bolgheri and in Tuscany The five kilometre Viale di Bolgheri runs across the coastal plain straight from the SS1 “Aurelia”, which it crosses at the village of San Guido, and leads up to the ancient village situated on the lower slopes of the hills overlooking the sea (Fig. 1). The two straight rows of cypresses of the Viale form a harmonious composition and an architectural planting which forms a vista with tree-like wings set, as it were, between two stages: the hillside village of Bolgheri and the land stretching towards the sea. The avenue is set in an area where the beauty of the surrounding countryside has remained largely unspoilt by indiscriminate urban and tourist development and where agricultural management enhances it further (Bezzini 1990). The cypress- lined road rises from the plain forming a spectacular, stately geometric line intersecting the flat land and the undulating hills. Visitors travelling along it are struck by the perspective before them and by the charming, enchanting atmosphere (Fig. 2). The poems that Carducci wrote about his childhood haunts in the Maremma, including the famous “Davanti San Guido” dedicated to this very cypress avenue, have helped to create the myth and fame that still surrounds Bolgheri and its Viale today. Overall, the Viale forms a landscape design which, placed harmoniously in the hilly countryside of Bolgheri, has acquired considerable cultural and environmental value. The Ministerial Order Fig. 1 – Panoramic view of of 21 August 1995 declared the Viale di Bolgheri to be part of the the village of Bolgheri and artistic and cultural heritage and, as such, subject to protection the Viale which runs across the coastal plain straight as provided for by Law nr. 1089 concerning the architectural heritage. The Viale represents one of the best known and, probably, the most famous examples of the symbolic, expressive role of cypress in Tuscany. In this region, cypress is no longer bound to the role of a funerary plant that was always ascribed to this tree in popular tradition, and instead takes on an auspicious, positive function. The cypress thus appears to be an intrinsic element of the Tuscan landscape, the result of a such a sensitive mixture of respect for the environment and the work and traditions of man as to be regarded as a quintessential symbol of the cultural identity of Tuscany. At Bolgheri the ornamental, cultural and historical value linked to this plant blend to create one of the most typical and charming effects. The common cypress (Cupressus sempervirens L.), that grows wild in Asia Minor and in the Eastern Mediterranean (Gellini and Grossoni, 1979), was brought to Italy by the Etruscans and the Romans, the latter using it mainly as a ornamental tree, for plantings around villas, monuments and sacred places. During the Renaissance the cypress enjoyed a revival in Tuscany when it began to be used once more to decorate the homes of the aristocracy, but also on account of its valuable timber and for use in agricultural work, so that over time it Fig. 2 - A perspective view of the Viale became a plant associated with rural life and labour. Planted singly or in small stands, near villas, churches, inns or crossroads, the cypress was used as a landmark by wayfarers and its timber was used to make shutters and frames, doors and furniture (Giannelli 2002). The outlines of this conifer are such a well-known sight today throughout Tuscany, from coastal areas to inland hillsides, that it is an essential, familiar element of a landscape that has now become famous all over the world. Torino, April 1st - 2 nd, 2004 103

The difficulty in the control of cypress canker disease Since ancient times, the common cypress has been considered a healthy, strong and disease resistant tree. Since the 1950’s, however, it has been facing a serious health problem: the Seiridium cardinale canker (Panconesi and Raddi, 1991). The gradual deterioration of an extremely important landscape and forest feature prompted investigation of a range of direct and indirect methods to control the spread of the disease and put a stop to this deplorable stream of losses (Fig. 3). So far the instruments that have proved most effective in controlling the disease have been sanitation (in terms of elimination of infected trees or portions of trees), to protect affected stands and ornamental plantations (Parrini 2003; Panconesi and Danti, 2003), chemical prevention in the nursery (Panconesi and Parrini, 1979) and genetic improvement of cypress as a deterrent for the spread of the canker and to restore affected formations (Raddi and Panconesi, 1998). The relevant Regional, Provincial and Local Councils have always been sensitive to the problem and have supported projects for the control of the disease. At EU level as well the cypress problem has been given attention since the seventies through the financing of four international research programmes that have Fig. 3 – A cypress of the led to important results of practical value, such as the selection of Viale severely attacked by S. cardinale a set of canker resistant cypress clones. Today, however, 50 years on from its first recording, as a result of the endemic nature assumed by the disease and the impossibility of dealing with the entire region in a brief space of time, S. cardinale canker continues to severely affect cypress, to the extent that, according to recent surveys, areas where the total of infected plants is nearly 50% are still common. Because of the symbolic value of this tree in Tuscany and central Italy, cypresses damaged by canker give tourists the impression that the area is carelessness and neglected.

The Protocol of Agreement for the conservation and restoration of theViale di Bolgheri The first serious symptoms of bark canker in the trees in the Viale occurred between the 1960s and 1970s, when bark canker reached epidemic level in many areas of Tuscany (Parrini, 1991). The planting of the trees in rows and mild, damp climatic conditions typical of the coastal area encouraged the development and reproduction of S. cardinale, favouring its spread throughout plantations. Consequently the Bolgheri cypresses have repeatedly suffered from various outbreaks of the disease, with severe damage and many losses being recorded over the years. For years they have been the subject of attention by the Regional Council, the Livorno Council, the Forestry Commission of and scientific institutions, alerted by the continual, inexorable, rapid deterioration affecting this monument. Interventions to protect the Bolgheri cypresses, started in 1979 and repeated during the 1980s and 1990s, have unfortunately been isolated and sporadic and, for this reason, have not controlled the disease effectively. Plant health surveys carried out in 1995 and 1999 continued to highlight the recurrence of serious attacks, both on trees that had previously been cured and on trees that had previously been free from the disease. While in 1995 surveys showed the need to fell 42 cypresses and to sanitise 400, in 1999, four years after the performed sanitation, it was once again necessary to fell 94 plants and treat 421. Towards the end of 1999 the continuous, unstoppable occurrence of damage and losses of the Bolgheri cypresses united governments and authorities responsible for the protection of the Viale in the need to carry out an urgent, organic, synergic programme of work to save the monument from deterioration and to go ahead with its improvement. Therefore the Provincial Council of Livorno, the Regional Council of Tuscany, the Local Council of Castagneto Carducci, the Superintendency of the Historical, Artistic, Architectural and Environmental Heritage of Pisa, ARSIA1, ARPAT2, ISZA3, the private owners of the historic cypresses and the CNR – IPAF4 signed an agreement in December ’99 for the creation of a 10-year project for the restoration and enhancement of the historic avenue. The ten-year programme was co-ordinated by the Provincial Council in a series of important, inter-related activities. Investigations based on tree health status and topographical surveys were followed by work aimed at treatment, restoration and maintenance, together with research work for the selection of canker resistant genotypes among the trees in the historic avenue. 104 International Congress on the Trees of History

Major programme operations and current status of the activities Planning and Intervention Two sanitation programmes, drawn up by the Provincial Administration and by the CNR, approved by the Superintendency, were completed in 2000 and 2002 respectively, with the aim of gradually reducing the incidence of cypress canker disease in the two rows along the Viale and in immediately surrounding areas. The drafting of the projects required the implementation of health surveys reporting on fungal and insect attacks, the recording of data in a specially created database, the preparation of descriptive printout and photographic testimony. Landscape experts were entrusted with a design study aimed at controlling and enhancing the presence of the undergrowth located intermittently along the two rows of the avenue, mainly consisting of shrubs typical of the Mediterranean area. Special attention was paid to Cercis siliquastrum, which is a spring flowering species that creates a wonderful colour contrast against the dark green of the cypresses.

Training Before sanitation works started, theoretical and practical courses were organised to train the workforce, aimed at increasing knowledge of the most important cypress diseases and their respective methods of control. Special attention was given to symptomatology, identification and spread of S. cardinale canker as well as methods of control the disease on infected plants, illustrating the basic criteria for correct implementation cuttings. Technicians from the Livorno Provincial Council, ARPAT and the Comunità Montane took part, together with operators from firms specialised in urban landscaping.

Restoration In the spring of 2002, 102 7-9 metre tall specimens of C. sempervirens var. pyramidalis were planted to replace previously felled trees. The planted trees, divided into 60 different canker resistant genotypes, were taken directly from CNR research fields (Fig. 4).

Maintenance Tests were carried out periodically throughout the year by the IPP-CNR and ISZA to assess the presence of problems due to fungal and insect attacks. In addition to S. cardinale infections, populations of Cinara cupressi aphids and Scolytids of the genus Phloeosinus require constant monitoring (Panconesi et al., 2003). In favourable years the former can cause extensive desiccation Fig. 4 - Specimens of cypress of the cypress crowns. Prompt treatments were carried out on clones selected for resistance to S. cardinale infections, some stretches of the avenue planting to prevent serious aphid which were planted along the infestations. The latter, by feeding on the shoots, may transmit Viale to replace previously infections of S. cardinale from diseased trees to healthy ones. felled trees Research (genetic improvement) Work aimed at selecting resistant genotypes of the cypresses in the historic avenue took place in stages. To date, 250 particularly vigorous and aesthetically valuable subjects have been propagated by grafting. The young saplings obtained from subjects propagated in 2000 and 2001 have already been planted in research fields where their ability to resist S. cardinale will be tested, and in a conservation field near the Viale. The plot of land for conservation is near San Guido and has been granted to the Provincial Council of Livorno under a free contract for twenty years by the owner, Marchese Nicolò Incisa della Rocchetta. The land has been suitably fenced off; planting, cultivation of the soil, weed-control and regular maintenance work are carried out by Livorno Provincial Council employees.

Computerization Zerobyte Sistemi is a firm in Florence which, under contract to, and in collaboration with the Local Council, IPP-CNR and ISZA, have set up a specially designed computer system to create a historical archive and to plan the work on the trees in the avenue. The system is based on the use of transponders (microchips) that issue a signal in code form so that once the sensor is inserted in the trees, it allows them to be immediately identified. Using specially designed software, it is possible to view and update reports and therefore organise a Torino, April 1st - 2 nd, 2004 105 database where the history of each tree is registered. The software has also been designed to assist the planning of work performed on the plants and to manage the accountancy aspects.

The European importance of the Bolgheri Avenue: the Interreg III B Medocc “Cypmed” project The ‘Cypmed’5 project, officially approved by Feder and by the Ministry for Transport and Infrastructures on 1.1.2002, aims to demonstrate the utility of the cypress as a multi- purpose plant for the improvement of the environment and the Mediterranean landscape, in the light of results obtained with genetic improvement during previous Community research programmes on cypress (Agrimed 1, Agrimed 2, Camar, Air). Thirteen Italian, French, Portuguese and Greek operative units are taking part in the project, which is headed by IPP – CNR. They are deeply involved in the ecological, economic and decorative-historical role of the cypress. As a result of a shrewd conservation policy put into operation by the Livorno District Council for the Viale di Bolgheri cypresses, an inter-disciplinary work group has been formed and asked to take part in the Cypmed project as a unique example of cooperation between public authorities and research institutions in a ten-year work project. The combined efforts of the CypMed members ensure both a range of urgent, correct interventions and European-level visibility of the problem “Ornamental Cypress – canker caused by Seiridium cardinale”. In addition, it promotes training of technical staff and the wide-scale dissemination of methods used for sanitation and recovery of cypress trees. The results obtained on the sanitation, replanting and management of the Bolgheri Avenue cypresses may be of great interest for the restoration of historical cypress plantations in Italy and in other Medocc (Western Mediterranean) countries. The inclusion of the Bolgheri Cypresses in the Cypmed project is recognition of an operation in which scientific progress is highlighted, confirming the international fame of the avenue that is visited every year by hundreds of foreign visitors who are captivated by such a wealth of natural beauty.

Bibliography Bezzini L., 1990 - Bolgheri. Bandecchi e Vivaldi Ed., Pontedera. Gellini R., Grossoni P., 1979 - Aspetti botanici del genere Cupressus. In “Il Cipresso: malattie e difesa”. V. Grasso, P. Raddi Ed.,Comunità Economica Europea, 27-43. Giannelli L., 2002 - Il cipresso. Storie e miti di terre toscane. Scramasax, Rep. San Marino, 151 pp. Panconesi A., Parrini C., 1979 - Nuove esperienze di lotta chimica contro il Seiridium (Coryneum) cardinale. Inf.tore Fitopatol., 29 (5), 13-17. Panconesi A., Raddi P., 1991 - Cancro del cipresso. Aspetti biologici ed epidemiologici. In “Il cipresso”, CNR, Regione Toscana, 49-60. Panconesi A., Danti R., 2003 - Quando risanare, quando abbattere. In “ La bonifica fitosanitaria a tutela del cipresso”. ARSIA, Regione Toscana, 67-78. Panconesi A., Danti R., Binazzi A., Roversi P.F., Pennacchio F., 2003 - Le avversità più ricorrenti del cipresso. In “La bonifica fitosanitaria a tutela del cipresso”. ARSIA, Regione Toscana, 15-35. Parrini C., 2003 - Presupposti teorici e risultati attesi dalla bonifica. In “La bonifica fitosanitaria a tutela del cipresso”. ARSIA, Regione Toscana, 59-66. Parrini C., Panconesi A., 1991 - I metodi di lotta contro il cancro corticale del cipresso. In “Il cipresso”. CNR, Regione Toscana, 94-109. Raddi P., Panconesi A., 1998 - Valorizzazione del patrimonio genetico per la resistenza al cancro del cipresso. Ann. Acc. It. Sci. For., XLVII: 45-53.

1 Agenzia Regionale per lo Sviluppo e l’innovazione in Agricoltura 2 Agenzia Regionale per la Protezione Ambientale della Toscana 3 Istituto Sperimentale per la Zoologia Agraria 4 Consiglio Nazionale delle Ricerche – Istituto per la Patologia degli Alberi Forestali (now IPP Istituto per la protezione delle Piante) 5 www.cypmed.cupressus.org 106 International Congress on the Trees of History

MONUMENTAL TREES INVENTORY OF THE PROVINCE PISTOIA, ITALY R. Ferretti*, M. Giachini, D. Giorgi**, M, Vannuccini *** * Executive of Territorial Resources Planning Service, Pistoia Province ** Independent professional *** Independent professional, Studio Tecnico Eureco

1. Introduction Monumental trees are a multifunctional resource, due to their naturalistic and historical relevance and to the important impact on landscape. In Tuscany, the value of monumental trees heritage has been recognized by the local law L.R. 60/1998. This law identifies the status of monumental tree, defines the rules for trees protection and valorisation and establishes a regional catalogue of monumental trees. The Territorial Resources Planning Service of the Province Pistoia, back in 1989, set up an inventory by which forty-one trees were identified, that according to their extraordinary age or size could be considered as “monumental”. Most of them are located in the mountain area of the province. The inventory was although not exhaustive, since it only took into account a part of the provincial territory: the lack of data and information about the wide district of municipalities of Pistoia, Montale, Pescia, Montecatini etc., leads to think that a consistent monumental trees heritage is still to be identified, also by taking in consideration the local dense historical villas system. In accordance with law 60/98 the opportunity to program protection and valorisation measurers is also given. These measures can although be only implemented on the basis of updated and consistent information on quantitative (morphometrical and dendrological data) and qualitative (physiological and sanitary conditions) characteristics of the trees and also about the changes of the area in which trees are located (SHIGO, 1993). In the frame of the new Co-ordinate Territorial Plan (P.T.C.), which considers monumental trees within the list of environmental resources of the province’s territory, a new initiative was taken in order to extend the inventory on the whole province and herewith establishes an exhaustive data base in relation to the trees’ consistency and health conditions, which will be integrated in provincial administration’s Geographical Information System. Particular attention will be given to geo-referencing trees’ locations, as a necessary premise to their correct identification on site.

2. Available information The available knowledge on the amount and conditions of monumental trees of the province Pistoia arise from four different sources which, at different times and with different criteria, attempted to assess the situation of the province’s green patriarchs. The first inventory, promoted by the National Forest Service (C.F.S.) in 1982, concerned the whole national territory. As far as the province Pistoia is concerned, thirteen monumental trees were singled out. Out of the twenty-two municipalities of the province Pistoia, only eight were represented, within the inventory, by at least one tree of extraordinary historical or monumental value. Municipalities such as Pistoia, Pescia and Quarrata, which represent a remarkable portion of provincial territory, contributed with no tree, whereas six monumental trees were identified in the territory of San Marcello Pistoiese. In 1989 the Provincial Administration of Pistoia performed an inventory by which forty-one monumental trees were identified, mainly located in the mountain area of the province and, in specific, in the territories of San Marcello Pistoiese, Sambuca Pistoiese and Abetone. In spite of the knowledge that was acquired through these census initiatives, only one tree of the province Pistoia (located in the municipality Lamporecchio), is actually inscribed in the Monumental Trees Regional List ex L.R. 60/98, out of a total of forty-nine trees setting up the list itself. In order to update and enrich the Regional List, the Regional Administration of Tuscany, in co-operation with the W.W.F., promoted the “Monumental trees in Tuscany” school contest in the school-year 2002-2003, addressed to the students of Tuscany’s schools. Thanks to this initiative, one-hundred and twenty-five trees were identified, eleven of which in the province Pistoia.These inventories, for several reasons, failed to give a global and exhaustive picture of the real situation of the monumental trees heritage on the wide territory of province Pistoia. If a comparative evaluation of all actions undertaken till now is performed, a basic incommunicability between different lists comes up. In other words, the regional list seems not to completely take into account the results of previous inventories. As a consequence, the Provincial Administration of Pistoia called out for an overall inventory which foresees the detailed analysis of the provincial territory, while updating and harmonising the information from previous initiatives. In particular, the lack of Torino, April 1st - 2 nd, 2004 107 knowledge about municipalities as Pistoia, Montecatini, Pescia and Quarrata, having a high incidence of remarkable villas and historical gardens, leads to think that a substantial monumental trees heritage is still to be identified.

3. Monumental tree inventory With reference to intervention measures foreseen by the regional regulations, which are put into effect by a specific action in the regional Rural Development Plan (P.S.R., Reg. 2057/99 EU), the present research and inventory initiative was set up according to some fundamental requirements: - Accurate trees’ geo-referencing, in order to obtain a certain tree identification on site, both for management and for eco-tourism activities. - Exhaustive description of sanitary and physiologic tree conditions, necessary to plan care and management measures. - Collecting exhaustive information about naturalistic, historical, traditional and landscape aspects related to each tree, in order to give to the regional Scientific Commission ex L.R.49/1995 (competent for evaluation of proposals for the admission to the regional list) as much information as possible, supporting the tree-candidates that will arise through the inventory. - Create an integrated management tool in accordance with the provincial Geographical Information System. The complete information collected throughout the inventory will be filed into a dedicated data base, developed in a Ms Access environment, linked to a point theme in shape format which stores spatial information (i.e. geographic location of each tree).

4. Research and documentation A preliminary documentation and research phase is essential for singling out monumental trees. Analysis of individual mentions, archive research, etc, will be collected and evaluated with the aim to obtain a wide range of preliminary knowledge. The primary information source is of course the provincial inventory of 1989, which will be eventually integrated with the results of the C.F.S. national inventory, and furthermore updated by recent acquisitions from the school contest organised by the regional administration and the W.W.F. Taking into account that a large portion of the province’s territory was not involved in the mentioned initiatives, it is of utmost importance to investigate documentary sources, which may lead to obtain remarkable information on monumental trees. For instance, the wide bibliography on historical villas and gardens is supposed to give suitable information, while also performing an analysis on local place’s names: quite often these names are originated by trees that were considered remarkable under a certain point of view. In order to collect direct mentions, a dedicated form was prepared, through which anyone can bring remarkable trees to notice. The form, which is accompanied by a short guide containing the requirements to which a monumental tree must be conforming, foresees that the user reports useful information for localisation of the tree and for a first screening of the received forms. The call for mentions will follow both institutional channels (municipalities, mountain communities, C.F.S. stations, etc.) and preferential channels in co-operation with environmental or cultural associations or any other institution having a direct interest on the territory. The inventory will also be promoted on Internet, by means of a web page linked to the web sites of the province, municipalities, and any involved association.

5. Monumental tree database In order to collect and file both field information and geographic data, a dedicated Geographical Information System was set up. Alphanumeric information, which means all quantitative and qualitative information, is managed by a data base developed in Access environment; spatial data (which means a point vector theme in shape format) is linked to the database via Windows ODBC protocol, and therefore the information can be managed directly in a GIS environment. The database is provided of proper forms for data input and visualisation, which allows a prompt data recall and change by the user. Data is recalled through several pages of access, each containing following information: - Tree identification, containing dendrological data and all useful information for the tree characterisation and localisation; - Tree conditions, containing morphometric data and a general description of physiological and biomechanical aspects; 108 International Congress on the Trees of History

- Sanitary conditions: the form contains specific information about a possible stress situation caused by biotic and/or non biotic factors and about identified pathologies, where applicable; - Management: the form contains a short report that summarises threats against the tree’s conservation, and technical and operative notes, in order to achieve a correct tree management and protection; - Monumental value: the form collects all available information about the historical, naturalistic, cultural and landscape values of the tree. Available data concerning the tree’s overall conditions (health and physiological status, biomechanical information) are also summarised on an analytical form, containing standard information, which is used both to obtain descriptive statistics about tree populations and also as a summary report that allows the field technician to keep the information during any future periodic inventory up to date.

6. Database contents In order to obtain information in the most standardised way as possible, a proper inventory form was prepared for field data collection, in which actual tree conditions are recorded. The inventory form is made up of keys recalling the tree characterisation and check, as well as indicators concerning tree location, structure, morphology and sanitary conditions.

Tree identification The form concerning the tree identification (Figure 1) reports some general information (identification code, species, date of first inventory) and the related photographic documentation. Furthermore, particular care is given to the tree localisation; as a matter of fact, geo-referencing the tree is of utmost importance in regards to the objectives of this work; therefore, an instrument assuring a high precision level in determining point location was chosen. The geographic location of each tree is therefore acquired by a Global Positioning System, transferred to a GIS software and finally reported in the regional technical cartography (CTR). The form contains: - Municipality, locality and eventually (for trees located in a garden or near a house) the street and the number of the house; - Gauss Boaga coordinates of the tree location; - Section of the regional technical map (CTR 1:10.000); - Land-registry references (sheet and parcel number): these references are requested within the authorisation procedures for different kinds of human activities, having an impact on the territory; therefore they represent an important control tool to check for possible modifications of the site. Finally, the property is identified (public or private) and references on the owner or the manager are recorded.

Figure 1. Tree identification form Torino, April 1st - 2 nd, 2004 109

Tree conditions The tree conditions form (Figure 2) reports, first of all, dendrological and dendrometrical main parameters, as circumference, diameter at breast height (this is actually a redundant data, but on the other hand the diameter allows to better assess the trunk size), height, height at which the green crown base starts (i.e. height of first living branch) and crown width (this is defined by the radius in the four directions, perpendicular one to each other). Some general information concerning the specimen to be preserved is also recorded: this can be an individual tree or a bio-group, which intended as a group of individuals originated by a single mother-plant and which cannot be classified as a single tree. The tree’s overall conditions are assessed through short descriptive reports concerning the location in which the tree lives (planting site), each of the tree’s main apparatuses (root system and collar, trunk, crown) and eventually recent management interventions. The soil and planting site aspects are of utmost importance for the evaluation of the roots’ water supply and the possibility to exchange gases. Therefore, some related aspects are put into evidence, as the kind of ground coverage, the soil compactness, eventual limitations to the root system’s development, morphological root anomalies, root decay symptoms, damaged roots, basal cavities etc. In reference to the trunk, some information about the morphology is registered and, eventually, damages and structural anomalies. In regards to the morphological aspects, the trunk inclination from the vertical axis is taken into account, as also any peculiar aspect such as V-shaped crotches, crooks, etc. Damages and anomalies due to factors having either a biotic and/or a non biotic origin are recorded, as indicators of pathologies or symptoms of reduced vigour or loss of mechanical wood stability. For instance, the following data is recorded: - Wounds on both bark or wood; - Emergence holes made by bark and wood miners; - loose bark or bark necrosis; - Cavities, of different depths and healing stadiums, due to pruning, wounds, wood decay and mechanical damages; - Wood decay fungi fruiting bodies, as symptoms of decaying wood, or visible wood decay; - Foreign body inclusions.

Figure 2. Tree condition form

In regards to the crown, all remarkable aspects are recorded, in order to describe tree’s physiological conditions and to make a precocious diagnosis of suffering conditions: - Presence of cavities, decaying wood and fungi fruiting bodies on branches; - Presence of dead or compromised branches; - Presence of pruning scars and wounds on main branches; - Presence of epicormic branches; - Stress symptoms due to pathologies of biotic or non-biotic origin, as leaves chlorosis and colour loss, leaves necrosis, cancers, microphyllia, crown dieback etc. Finally, some conclusive consideration on physiological and sanitary conditions are reported (in the section vegetative state) as a synthetic description of actual tree state. 110 International Congress on the Trees of History

All collected information by means of descriptive reports, can be viewed in a synthetic way through the analytical form (Figure 3), which allows to export data in an Excel file for statistical analysis or in order to produce final reports about the whole tree population. The analytical form consists of standard voices which allow to define the tree’s overall conditions.

Figure 3 Analytical form

Health condition This section contains a report about tree’s sanitary conditions, with a particular look at pathogens. The form contains photographic documentation related to present pathogens (insects, fungi, bacteria, etc.) and also any possible non biotic damage. The contents of this section can be viewed in the analytical form, too.

Management The section related to tree management contains the guidelines about the proposed future tree management interventions, while also putting in evidence any need to go into further depth on specific aspects. The reported interventions can be determined either by an immediate need for safety assurance or by a long-term planning, which, for instance, might be a site environmental improvement. Here below the possible intervention measures are reported: - Hazard tree assessment, which may be applicable for all trees located in areas with a high frequency of visitors and whenever symptoms of reduced carrying capacity are present (MATHENY & CLARK, 1994). The mentioned assessment is therefore strictly restricted to risk situations which require extraordinary management measures (BRELOER & MATTHECK, 1998); - Pruning is foreseen either as an extraordinary measure where a risk condition is given, or in case a clear negligence on planned intervention measures is assessed. Pruning prescriptions go always together with detailed operative technical notes and also specific photographic documentation; - Consolidations: these arboricultural tools are intended to prevent branch collapse through the use of moorings and supports, while also preventing from branch injuries occurring during branch fall, which is obtained by establishing predetermined falling directions; - Site improvement management measures; for instance, waterproof paving removal, soil improvement through agronomic interventions, etc. - Preventive or corrective sanitary treatments. This section also reports the main biomechanical parameters taken into account by the S.I.A. (Static Integrated Assessment) method. S.I.A. allows the assessment of some tree static characteristics by simply surveying dendrometrical parameters, as, for instance, tree height, dbh and crown shape. Once this data is assessed, through statistical models which were identified for each tree species, the base carrying capacity can be determined (a parameter that concerns the tree structural dimensioning), as well as residual wall thickness which is required in order to have a trunk with a 100% base carrying capacity (below this value the tree is under-dimensioned towards the crown loading). S.I.A. parameters were addressed within this work in order to obtain a first evaluation about the tree static characteristics and also to have a base reference for any future deepening needs on the hazard tree assessment. Up to present, S.I.A. models are available only for certain tree species, while static-morphologic mathematical relationships for many Mediterranean species (helm, cypress, etc.) are still to be investigated. Torino, April 1st - 2 nd, 2004 111

Figure 4. Management guidelines form

Monumental value In the last section all information related to naturalistic, historical, architectonic and landscape aspects or reference to local use and traditions linked to the trees is collected. According to Regional Law 60/98 a monumental tree is not only a tree of extraordinary size or age, but also a tree having a precisely defined reference to historical events or to local traditions. The documentation related to these specific aspects is therefore necessary to sustain trees’ candidates for the insertion in the regional list. This is moreover useful information for the tree valorisation (by means of informative activities) and for promoting the province’s natural heritage in the frame of environmental tourism.

7. Conclusions The described research and inventory programme on monumental trees in the province Pistoia is, at present, the most complete and exhaustive experience in the Tuscany region. This inventory, which is based on a solid arboricoltural basis, does not only allow to identify and register monumental trees, but it permits also to obtain a wide knowledge base, which is a useful tool for any management, protection and valorisation activity. Under a technical point of view, the collected information will provide a useful basis to develop a management disciplinary tailored on each tree, which can then be put into practice thanks to financial measures that are foreseen by regional laws, but which are also taken into account very seldom. Taking into consideration that monumental trees can be considered as a rural landscape promoting tool, the set of information that was collected can be used to promote environmental tourism and educational initiatives. The available digital archive, would in any case find in the web its natural divulgation mean.

References WESSOLLY L., 1995. Fracture diagnosis of trees. Part:2 Static Integrated Methods – Statically Integrated Assessment (SIA). The practitioner’s method of diagnosis. Stadt und Grun, 8: 570- 573. AA.VV., 1989. Censimento delle piante monumentali (L.R. 82/82). Provincia di Pistoia, 92 pp. BRELOER H., MATTHECK C., 1998. La stabilità degli alberi. Fenomeni meccanici e implicazioni legali dei cedimenti degli alberi. Il verde editoriale, Milano, 281 pp. SHIGO A.L., 1993. A new tree biology. Shigo and Trees Associates, Durham, New Hampshire. MATHENY N.P., CLARK J.R., 1994. A photographic guide to the evaluation of hazard trees in urban areas. Ed. International Society of Arboricolture (U.S.A), 85 pp. 112 International Congress on the Trees of History

CURES OF MONUMENTAL TREES: A METHODOLOGICAL APPROACH F. Grisoni, E. Viotto, M. Palenzona IPLA S.p.A. - Torino

Abstract In application of a regional law (n°50, 3.04.1995), “Protection and Evaluation of Piedmontese Monumental trees with high naturalistic and historical importance”, Piedmont Region has started a series of activities: catalogue and protection of monumental trees. Since Spring 2000 until today, IPLA, in collaboration with the Department for Evaluation and Protection of Agroforestry Resources (Turin University) and with the Italian Forestry Corps, has realized activities of planning, management and cures. By indications of a special Regional Commission, each subject or group has been accurately described, according to its morphological characteristics, and then cured. During three years of work, treatments were applied to 39 arboreal groups mainly belonging to native species and chosen homogeneously in the Piedmont Region. On the base of the tree health, a different kind of cure has been selected: dry branches elimination, pruning, recovery. Today it can be stated that the treated plants appear such vigorous as to assure a majestic future presence. Therefore, constant monitoring and on-time-treating is of primary importance, in case of new health problems.

Introduction By a Regional Law (n°50, 3.04.1995), “Protection and Evaluation of Piedmontese Monumental trees with high naturalistic and historical importance”, attention is addressed to these “living monuments”, because their presence can contribute to improve the regional landscape, and its environmental and cultural evaluation. The law provides for a catalogue of the Piedmont monumental trees (single trees, groups or monumental tree rows); their protection, by Regional financing of ordinary and extraordinary cures; the promotion of actions to evaluate and know monumental trees and understand the importance of their protection. Since many years, IPLA (Istituto per le Piante da Legno e l’Ambiente, Turin, Italy) has been working with the DI.VA.P.R.A. (Department for Evaluation and Protection of Agroforestry Resources Turin University) and with the Italian Forestry Corps, in order to apply the 50/95 Regional Law. Because of its technical – practical competences, IPLA has been involved in pilot activities of cures planning and realisation, since the beginning of this project. The aim was to cure and recover particularly interesting trees from the monumental point of view. Later on, IPLA was involved in the monumental trees catalogue and in spreading this kind of activity, also because of its contacts with many Piedmont Municipalities. Since Spring 2000 until today, IPLA was charged by the Region with the task to carry out an annual activity of works planning and management, realisation of cures and evaluation, on monumental trees according to the Regional 50/95 Law. The main objective of these activities is to provide a methodological example by treating a chosen group of trees. On the trees marked by a special Regional Technical Commission, IPLA has supervised the provided activities and finally produced technical and explicative cards to be spread out.

Materials and methods The first step of the project is to choose trees to be treated. IPLA technicians, in collaboration with the Turin University researchers, made preliminary field surveys to estimate characteristics of each tree indicated by the regional Technical Commission. During this first inspection, the location has been verified and a preliminary picture of the tree has been described, including a summary of the main health problems. Later on, the following activities have been developed on each chosen tree: I) Primary visual inspection An accurate description was performed, with particular attention to the phyto - sanitary and static conditions. In details, the following aspects were analysed: • apparent energy (new foliage development, presence and diffusion of dry leaves, crown colour); • root anchorage and potential dangerous situations depending on rooting specific sites (asphalted or transit areas, slopes, presence of manufactures or stagnant waters, ecc.); • crown form (regular, eccentric, unbalanced); • branch ramification characteristics: protrusion from main axis, insertion angle into the Torino, April 1st - 2 nd, 2004 113

trunk, inner and external injures (wounds, breakages, damages from lightning, tense wood, torsion effects, cavities, malformations, ecc); • injuries in the trunk or at the tree foot; • presence, shape and health of roots (development, emergence, phyto - sanitary conditions, ecc.); • presence of all types of phyto – pathologies, in particular of butt rot fungi. II) Treatment programme After a preliminary tree analysis, the plan for the main treatments has been defined. The following kind of cures were provided: • pruning for foliage reduction and safety measures, to lower the sail effect of apex parts (especially the lateral branches exposed to winds and far from the main axis), by lightening malformed branches; • pruning dry branches to avoid the danger of unexpected falls; • disinfection of superficial wounds on healthy wood by cupric oxychloride solutions, in order to improve plant reactions against wood fungi attacks and to preserve mechanical resistance of trees; • in case of open large wounds, operations of dendro-surgery by removing decayed and injured wood parts, to eliminate infection sources (recovery), and subsequent treatments on wood by cupric oxychloride; • wound dressing: application of seals (usually thin lead slabs) over open-up wounds more subject to wood decay because of rainwater infiltration; • wound dressing: application of protection nets, to preserve cavities from storage of vegetal detritus (leaves, ecc.) and/ other materials; • rod bracing to consolidate the unbalanced ramifications by anchoring branches, with opposite barycentre, tied each other to compensate tensions, or by anchoring the most divaricated and dangerous branches to the trunk; • realisation of specific and special supports to fix great and too much unbalanced branches, if rod bracing is not possible; • indication of integrated works to improve landscape and monumental values and the tree protection (for example, pruning on contiguous trees, realisation of flower beds with protection curb, ecc). IPLA has consulted Turin University specialists to choose the specific cures to the most difficult cases of stability and vegetative decay. During this phase, also site accessibility has been studied and the most suitable tools to operate on tree crowns has been chosen. A specific field card (fig. 1) has been utilised to describe trees and observe the main characters (point I and II). Denomination and location of the analysed monumental tree, site accessibility, tree description and suggested cures, final evaluation and list of photos are reported on this card.

Figure 1. Field card 114 International Congress on the Trees of History

III) Works management Cures have been usually performed by “Airgreen” of Fratelli Airaudi, Robassomero (TO), that has realized the jobs according to indications and supervision of the IPLA technicians. Different models of hoists have been utilised. They are suitable to catch up the higher and majestic tree tops and can get in and work in the less accessible crown parts. In some cases, difficult access to the site tree has imposed the use of special tools: self-moving hoists mounted on crawlers (fig. 2), able to drive off the roads, on mountain tracks, and to reach out of the way sites, as, for example, the Strobe Pine of Chiusa Pesio (CN) and the Ilex of Rigoroso – Arquata Scrivia (AL).

Figure 2. A particular type of hoist Figure 3. Tree climbing technique is used to mounted on a caterpillar tractor. prune trees unreachable by mechanical Chiusa Pesio (CN) means. Pietraporzio (CN)

In other cases, operations were carried out by the aid of stairs and “tree climbers”, pruners that climb the plant and work using ropes and hooks (fig.3). Two example are the Chestnut tree of Crodo (VB) and the Larch of Pietraporzio (CN).

Results During the three years (2001-2003) of work, cures were performed on 39 trees or arboreal groups (fig. 4). The chosen plants, placed in homogenous patterns in the Piedmont region (fig. 5), belong mainly to native species; only in some cases they are exotic, like, as an example, the Sequoias of Burcina Park (BI) and Roccavione (CN) or the Gingko of Casalbeltrame (NO). Faced problems were very heterogeneous: in some cases treated trees presented only dry branches (for example the Ilex of Rigoroso, AL, and the Larix of Rima, VB); in other cases the crown was so poorly balanced and badly conformed that specific re- balancing and crown reduction tinning was necessary (for example, the Yew-tree of Cavandone, VB, and the Horse-chestnut of Casorzo, AT). Sometime many wood decays were detected so recovery techniques were to be used (for example, the Cedrus of Montalenghe, TO, the Chestnut of Bioglio, BI, the Ash of Moncenisio, TO); finally, some trees were so injured and presented so complex problems that a specific recovery project was necessary; it usually included not only the common cures but also the realisation of particular supports (for example, the Lime of Macugnaga, VB, the Planes of Savigliano, CN). Described and treated plants appear sufficiently such vigorous as to assure a majestic presence along time. Obviously, the necessary conditions are their constant monitoring and on-time execution of the necessary cures in order to avoid serious damages to the tree in the future. Torino, April 1st - 2 nd, 2004 115

Figure 4. List of treated trees

Figure 5. Distribution of the Trees in the Piedmont Region

In the first enclosure, some pictures of some types of cures, executed during the project, are reported.

Acknowledgements The authors thank very much Federica Spaziani and Annamaria Ferrara who helped to write this work and Fabio Petrella who helped to translate it into English 116 International Congress on the Trees of History

First enclosure Pictures of the main types of carried out cures Torino, April 1st - 2 nd, 2004 117 118 International Congress on the Trees of History Torino, April 1st - 2 nd, 2004 119 120 International Congress on the Trees of History Torino, April 1st - 2 nd, 2004 121

THE “PRODIGIOUS” CYPRESS OF SAN BENEDETTO IL MORO D.S. La Mela Veca*, M. Ala*, F. Terranova** and G. Barbera* * Dipartimento di Colture Arboree, Università di Palermo ** Centro Regionale per la Progettazione e il Restauro, e per le Scienze Naturali ed Applicate ai Beni Culturali, Assessorato dei Beni Culturali ed Ambientali e della P.I., Regione Siciliana

1. Introduction In the Mediterranean culture, the cypress is traditionally a sacred tree, often with funeral meaning. The Etruschi, the Greek and the Romans used to represent it on the funeral urns. The cypress was devoted to Plutone and was planted in front of the doors as mourning, the funereal crowns had been woven with leafy branches of myrtle and cypress. As funeral trees, the cypress is remembered by Plinio and sung by Ovidio and Virgilio (CHIUSOLI, 1979). The sacredness of the cypress is confirmed by an old imposing exemplar, considered as the oldest tree in Palermo (PINTAGRO, 1992). It is located next to the fifteenth-century convent of Santa Maria di Gesù in the outskirts of the city. According to the tradition, cypress is sprouted miraculously from a fixed baton in the ground by S. Benedetto il Moro, born of Ethiopian slaves in 1524. He lived for a long time like a hermit and therefore, since 1562, lived in the convent, with the exception of a brief permanence in the convent of Sant’Anna in Giuliana, up to 1589. He was considered a holy thaumaturge man, he was patron of Palermo and he was known through the Franciscan Order and the Spanish Court also in Spain and in Latin America. He was canonized by Pio VII in 1807. His body is conserved in the Church of Santa Maria di Gesù and it is still today an attraction of pilgrimage (DELL’AIRA, 2003; FIUME, 2000).

Figure 1 - The cypress of San Benedetto il Moro with the Conca d’Oro in a press of 1840 (drawn from “Pictures from Sicily”, London)

According to the legend about the veneration of the Saint, the thriving cypress - next to the chapel where Benedetto stopped for praying, located not very far from the convent along a path of the slopes of Mount Grifone which is used for celebrating of the via crucis - had been grown through a baton used by him. The exceptionality of the cypress is testified also by a habitus considered unusual for the disposition of the principal branches on the stem that is derived from the fact written in 1612 by the great Spanish dramatist Lope de Vega, “il frate nero piantò (il bastone, ndr) capovolto nel terreno prima di morire. I suoi rami non spiovono intorno come quelli degli abeti comuni. Si allargano verso il cielo, alla rovescia” (DELL’AIRA, 1995). The cypress is either important for its great historical and religious meaning, or for its presence connected to the cult of a very popular and revered Saint. It is surely a monumental tree for its age, dimensions, visibility in the landscape, history and religious values (PAVOLINI, 1999). The dating and the analysis Visual Tree Assessment (VTA) of the cypress, further to have a religious value, (the necessity of the miracle would be denied by a non compatible age with the years of the permanence of the Saint in the convent), constitutes an important contribution to the knowledge of the richest vegetable patrimony of a city, whose suburban territory (the Conca d’Oro) is known to the historians of the environment and the agriculture as “di antico e quasi mitico predominio dell’albero” (BEVILACQUA, 1996). For the dating of the tree has been carried out a dendrochronological analysis. Through the dendrochronological approach with the simple determination of the number of rings of growth in the stem is, in fact, possible to determine the age of the tree investigated and to quantify, potentially, the relationships between plant and environment (CORONA, 1980). 122 International Congress on the Trees of History

2. Location, environmental and botanical aspects of the study area The cypress of San Benedetto is located in the park of pertinence of the convent and the monumental cemetery of Santa Maria di Gesù at an altitude of 190 m a.s.l. and at slopes of Grifone Mount, in the southern part of the city of Palermo (Fig. 2).

Figure 2. View of the Convent and of the monumental Cemetery of Santa Maria di Gesù The area represents a roughed morphology with superior inclinations over 40% and with exposure N-NW. The climate is characterized by mild temperatures and precipitations like those regional. According to the Rivas-Martinez bioclimate classification the climate is upper Thermo-mediterranean-subhumid. The local primary vegetation probably was a mixed Mediterranean oak forest dominated by Quercus virgiliana and Quercus ilex, while the areas characterized by shallow soil and a warmer climate were probably characterized by an evergreen sclerophyllous maquis. Despite the strong human impact on the territory, on the NW slopes of Grifone Mount grow different species of the Rhamno alaterni-Quercetum ilicis, an evergreen plant community typical on limestone slopes of the coastal area of Palermo Mounts (BRULLO and MARCENÒ, 1985; GIANGUZZI et al., 1996) (Fig. 3).

Figure 3. Shrub community near the cypress of San Benedetto il Moro

On the slopes along the path which from the sanctuary takes to the cypress, it is possible to notice some pre-forest vegetation fragments belonging to Oleo-Ceratonion siliquae alliance, grassland features belonging to Hyparrhenion hirtae alliance, as well as rocky cliffs communities referable to Dianthion rupicolae alliance. The actual landscape is characterized by rock outcrops and by xeric and poor grasslands, dominated by Hyparrhenia hirta. Elsewhere are present several species quite common in open maquis (Oleo sylvestris-Euphorbietum dendrolidis), such as Olea europaea var. sylvestris, Euphorbia dendroides, Ceratonia siliqua, Prasium majus, Asparagus albus, Calicotome infesta, Ruta chalepensis, Teucrium fruticans, and many species of the more mature maquis communities (Rhamno alaterni-Quercetum ilicis), such as Fraxinus ornus, Pistacia terebinthus, Rhamnus alaternus, Asparagus acutifolius, Rosa sempervirens, Rubia peregrina, etc. In the recent past these semi-natural and subnatural communities have been overlapped with Pinus halepensis, Pinus pinea, Cupressus sempervirens and Acacia saligna plantations. Despite their high density, within them it is possible to observe quite remarkable processes of early naturalization stages. Near the convent and inside the cemetery there are different monumental individuals of cypress (Cupressus sempervirens). The most imposing one is actually the cypress of San Benedetto (C. sempervirens var. horizontalis), which grows isolated on the slopes of Grifone Mount near the chapel dedicated to the Saint (Fig. 4): its circumference is 3.50 m (at 2 m above ground) and its height is 23 m. Torino, April 1st - 2 nd, 2004 123

Figure 4. The cypress of San Benedetto il Moro today. The background which remains of Conca d’Oro

The crown shows some empty spaces because of the desiccation of different branches, especially in the basal part. The stem also is damaged probably caused by fires and buttresses typical of old trees.

3. Dating and stability of the cypress of San Benedetto il Moro 3.1 Methodology For the dating has been taken out a tree core with the incremental borer of Pressler in a height of around 25 cm from the ground. In laboratory the tree core has been pasted on a wood support with a central groove. In order to examine the transversal section, there has been performed the pasting of the core taking care of that the woody fibres which were put in orthogonal way on the plan of support. The tree core has, finally, been smoothed with a thin abrasive paper (100, 250 and 400), in order to underline the growth rings and to make easier their reading and measurement (Fig. 5). The preliminary phase of analysis of the sample was the cross-dating (FRITTS, 1976) which means giving the exact forming year of every single ring. This operation has been performed with a stereoscope dating the series beginning from the last ring that is formed under the bark. The dating has been performed comparing the series with another of a near cypress of inferior age.

Figure 5. Pasted and smoothed tree core, ready to be analyzed The comparison has been effected considering the total thickness of the rings (characteristic rings), the thickness of the zone with the spring and summer wood, the mean vase dimension and the presence of possible scars (SCHWEINGRUBER et al., 1978). The individualization of characteristic rings has a fundamental importance to resolve doubtful cases and to individualize absent or double (false) rings. The dating has been very difficult because of the irregular rhythm of growth of the species that often determines the formation of false rings. The cypress, for such reason is considered by dendrochronologists a trouble - making species. For these reasons the cypress is a low studied species, although in Italy have been done some short chronologies and well cross - dating on trees located in the southern Appennino (Salerno and Potenza) by CORONA (1970). The individualization of false rings has been, in our case, difficult because was examined only a small section of the plant (only one tree core, not being able to withdraw others for the presence of an adjacent wall on the base of the stem) so it hasn’t been possible to verify if there were vanished false rings which are absent in the whole circumference. In 124 International Congress on the Trees of History order to recognize the absent rings it has been necessary to start from the consideration that they differ from those true. The true ones showed an early thick and a late thread-like zone. Furthermore, in the true rings, the limit between the late and early zone is marked but that one between the early and late zone is a little vanished. In the conifers generally the false rings are separate from those true because of their external part which is less intensely coloured (UZIELLI E NARDI BERTI, 1979; GIORDANO, 1981) (Fig. 5). The thickness of rings has been measured with the dendrochronograph LINTAB 3. The measures have been performed with a precision of 1/100 mm beginning from the first ring at the centre of the tree. Considering that the cypress of San Benedetto is a monumental tree, we have also effected, in sight of possible protective interventions, an analysis of the stability according to the criterions of evaluation established by the methodology VTA (MATTHECK E BRELOER, 1998) and according to the suggestions by the “Protocol ISA on the Evaluation of the Stability of Trees ©” that provide a visual and instrumental examination. The data sampled has been transcribed on a special card, which will constitute a general updating of informative base for the following instrumental analyses e/o for the evaluation of the level of stability in order to define the possible necessary interventions and the periodicity recommended for the following controls. The instrumental examination has been performed using the Resistograph (model F400 S) and the fractometer. The research has been assembled at the base of the stem, and from a first visual investigation, has been underlined a light camber, a possible symptom of inside degradation. There have been effected 5 tests in order to investigate the whole circumference of the stem. The tests with the fractometer (3 measurements) have been performed on a tree core, withdrawn in correspondence of the resistograph survey n. 1, with the purpose to determine its moment of breaking.

3.2 Results The Cypress of San Benedetto is 426 years old and, therefore, it is born in 1577. In the figure 6 are represented the elementary chronology of the tree. Being formed from a single ring series, it can be suffered from errors due to the individuation of false rings. Its annual mean growth has been of 87,88 cents of mm; after a first short period of slow growing, and then about two hundred years of sustained growth followed by a slowdown. However there is large variability in tree-ring width probably due to exceptional climatic events e/o troubles of human origin, mainly fires. The progress of the broken one is sufficiently homogeneous and typical of isolated tree.

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Figure 6 - Elementary chronology of the cypress of San Benedetto il Moro The resistograph profiles don’t clearly underline the growth intervals because the transition between early and late zone is gradual. However it has not been possible to compare the profiles with the graph derived by the dendrochronological study of a tree core withdrawn immediately on the resistograph profile n. 1 (Fig. 7). For the analysis of the stability, the graphs got with the Resistograph showed, along their length, a regular progress. The increasing progress of the graph from the outside of the stem toward the inside is caused by a greater content of extracted. This helps to increase the density of the heartwood in comparison to the sapwood. The investigations with the resistograph and with the fractometer have not underlined wood degradation. The fractometer tests performed on the tree core have underlined values of the parameters Torino, April 1st - 2 nd, 2004 125

(moment of fracture and angle of fracture) comparable with the safety limits drawn by field studies on trees of the same species. Visual analysis has, in fact, pointed out light defects of form and small anomalies. The risks of the crashing down are referable to those of the class A. The light morphological anomalies can get worse in the time. From the visual analysis have not been found, however, symptoms of degradation in the stem and in the principal branches. A light torsion of fibres noticed on a branch, as light lines on the stem, take part of the morphological characteristics of the species and they are common in old trees.

Figure 7 - Profile n. 1 of resistograph analysis

4. Conclusions Dating performed using dendrochronology analysis has allowed to certify that the tree is about 426 year old. Going back for an equivalent period of time, we reach 1577 that is almost in the mean of the period of permanence of the Saint in the convent (1567-1589). Beyond every fideistic approach it is possible that San Benedetto has transplanted in that place, less probable - for the difficulty of the cypresses to take root by cutling - that originates from the Saint’s baton! Its crown shape (Fig. 4) considered “strange” and its old age, in fact, are perfectly compatible with the fact that the tree belongs to the variety of horizontalis. In fact, the historical image goes back to 1840 and shows a typical cypress of this variety; following alterations which could have been caused by winds, lightnings and fires. The research has surely confirmed the elevated historical-religious value of the monumental tree which in the future merits to mostly be protected and respected. The analysis of stability has also allowed to give useful indications to its safeguard. On the stem has been observed, died fragments caused by precedents badly cuts susceptible of degradation. It is advisable, therefore, the trimming of the same to avoid that the agents of degradation can pass to the healthy portions of the wood inside the stem. Furthermore, on the internal part of crown there are different died ramifications of first and second order that makes opportune pruning practice. Besides, the pruning is important to decrease the resistance of the crown against the wind. Dealing with a subject of the crashing down risk belonging to the class A, it is necessary a biennial visual analysis and an instrumental verification after three years. The results encourage to keep on studying the dendrochronology of the cypress in order to draw information on the climatic history and on the quality of the air of Palermo.

Acknowledgements A particular thanks to Salvo Pasta for his contribution for the floristic analysis and to Carlo Di Leo for the stability analysis.

Bibliography

BEVILACQUA P., 1996 – Tra natura e storia. Ambiente, economie, risorse in Italia, Donzelli Editore, Roma. BRULLO S., MARCENÒ C. (1985) - Contributo alla conoscenza della classe Quercetea ilicis in Sicilia. Not. Fitosoc., 19 (1) (1984): 183-229. CHIUSOLI A., 1979 – Il Cipresso nell’arte e nel paesaggio. In: Grasso V. e Raddi P., Atti del seminario “Il cipresso. Malattie e difese”, Firenze, 23/24 Novembre, pp.19-25. CORONA E., 1970 – Valore dendrocronologico del cipresso sempreverde. Monti e Boschi, 21 (9): 21-25. CORONA E., 1980 - Il contributo della dendrocronologia in alcune ricerche storiche. Annali dell’Accademia Italiana di Scienze Forestali, 29: 265-286. DELL’AIRA A., 1995 – Commedia famosa del santo nero Rosambuco della città di Palermo. Introduzione e versione italiana. Palombo, Palermo, pag. 35. DELL’AIRA A., 2003 - San Benedetto il Moro tra Sicilia e Galizia. Kalòs – anno XV n.2, Palermo. FIUME G., 2000 – Il Santo Patrono e la città.San Benedetto il Moro: culti, devozioni, strategie di età moderna. Marsilio Editori S.p.A., Venezia. 126 International Congress on the Trees of History

FRITTS H.C, 1976 - Tree Rings and Climate. Accademic Press, New York. GIANGUZZI L., I LARDI V., R AIMONDO F.M. (1996) - La vegetazione del promontorio di Monte Pellegrino.- Quad. Bot. Ambientale Appl., 4 (1993): 79-137. GIORDANO G.¸ 1981 – Tecnologia del legno. Volume 1. La materia prima. UTET, 100-109 e 232-234 pp. MATTHECK C. E BRELOER H., 1998 - La Stabilità degli Alberi. Il Verde Editoriale. NARDI BERTI R., 1993 – La struttura anatomica del legno ed il riconoscimento dei legnami italiani di più corretto impiego. Contributi scientifico-pratici, XXIV: 892-893. PAVOLINI M., 1999 - Alberi monumentali e territorio. Evoluzione geostorica, considerazioni fitogeografiche e valenza dei grandi “patriarchi” italiani. Rivista di Storia dell’Agricoltura, Anno XXXIX, n°1: 4-32. PINTAGRO M., 1992 – Arborea. La storia di Palermo in cento alberi illustrati. Helix Media Editore, Palermo. SCHWEINGRUBER F.H., FRITTS H.C., BRAKER O.U., SCHAR E., 1978 - Dendroclimatic studies on conifers from central Europe and Great Britain. Boreas, 8: 427-452. UZIELLI U., NARDI BERTI R., 1979 – Aspetti tecnologici del legno di Cipresso (Cupressus sempervirens L.). In: Grasso V. e Raddi P., Atti del seminario “Il cipresso. Malattie e difese”, Firenze, 23/24 Novembre, pp.95-109. Torino, April 1st - 2 nd, 2004 127

INVENTORY OF THE VETERAN TREES DESERVING PROTECTION IN THE PROVINCE OF FERRARA E. Mantovani1, G. Morelli2, L. Raspanti3, The Committee for the Safeguard of Trees in the Ferrara Province4 1 Provincial Administrator in Ferrara; 2 Professional, Ferrara; 3 Professional, Bologna; 4 The Committee for the safeguard of trees in the Ferrara Province comprises the representatives of the following associations: Friends of the Ferrarese Museums and Monuments, AREA, “Unione” circle, Deputazione di Storia Patria, the Biology Department of Ferrara University, the Faculty of Architecture of Ferrara University, FAI, Ferrariae Decus, Ferrara Garden Club, the UNESCO-Ferrara group, ITALIA NOSTRA, Legambiente, LIPU, the Roll of Forest Agronomists of the Ferrara Province, the Ferrara Naturalists’ Society, WWF

Introduction In 1977 the Emilia-Romagna Region established, according to the Regional Law n. 2 of the selfsame year, the preservation and safeguard of “arboreal specimens, single or grouped, in copses, in rows, of outstanding scientific or monumental interest”. The basis for this legislative norm was a summary inventory, carried out on the principle of the unprompted notice on the part of local administrations of the trees, both privately and publicly owned, that seemed deserving protection. In the context of the Emilia-Romagna Region, the Province of Ferrara appeared to be the least endowed with trees having a monumental character, with a total of 20 protected single trees or groups of trees, i.e. only 3.12% of the overall patrimony of the Emilia-Romagna Region. Next to these trees another 60 trees were mentioned, identified as “remarkable”, whose botanical and environmental importance was recognized, but no specific control was provided for them. As from 2003 the Province of Ferrara has decided to see to the updating of the information relative to the protected specimens, entrusting the survey relative to the Ferrarese territory to the Studio Progetto Verde, together with Ms. L. Raspanti, agronomist. At the same time, the Province of Ferrara has started a program for the identification and the valorization of the environmental pity points that, starting off from known and verified data, would then merge all the available data, and then proceed to a rational management of the whole of the provincial patrimony. In practice, this is an inventory that requires a careful and thorough survey, as of now still in progress, on the presence in the territory, of “vegetation emergencies of the arboreal and shrub type” linked to the landscape, with particular attention to the arboreal specimens possessing monumental importance. The present study illustrates the methods by which this survey will be carried out, anticipating some of the results already achieved.

Materials and methods The elements of the landscape with which the Ferrara Provincial Administration is concerned are: single trees, copses, rows of trees avenues, hedges, traditionally planted orchards of typical trees, rows trees planted for vine-bearing. Limiting the treatment to single trees only, the information to be gathered are the following – dendrometric, morphologic and architectonic data, conditions of visibility and accessibility to the site, and the perception of the tree in the landscape, that is its relevance to the landscape. The survey operations have been organized according to a feed-back principle and can be schematically described in the following way: 128 International Congress on the Trees of History

The first process entails making the local authorities, in particular municipals, aware of the need to signal the elements worthy of entering the inventory, using as a prop a summary survey card called “Individuation file-card” (Attachment n.1 – Individual file-card for single tree) The whole corpus of these reports, together with those produced by the Committee for the Safeguard of Trees is received by the Province through the second process. The evaluation of the incoming data allows the identification of the elements in the landscape actually deserving protection. For these, through the third process, an actual inventory is activated, which requests a detailed survey chart, called “ Complete specialist file-card” (Attachment n.2) filled in by the professionals. This stage is also accompanied by the topographical identification of the tree, by means of G.P.S. technology, ad by its position on specific thematic maps. In the detailed survey, particular importance is given to photographic data, which must significantly illustrate the data described in the file-card. All gathered information, organized on computer, is given back to the Province though the fourth process, so as to be reorganized and used for management, planning and information aims.

Results As already said, the work is still in progress, and it is thus impossible, at the moment, to produce data on the scope of heritage of monumental trees of the Province of Ferrara, or on its intrinsic features. Nevertheless, a first summary of the surveys carried out for the updating of information relative to the trees protected under regional law n. 2, 1977, allows us some fundamental considerations. The data gathered in the past on the basis of spontaneous information without successive verification are approximate and often incorrect. A simple spontaneous indication does not permit an exhaustive picture of the veteran trees that are actually present in a given area which, in the case of the Province of Ferrara, seems to be much richer in valuable arboreal elements than the historical data in possession of the Province indicated. The lack of updating available information, lasting more than two decades, supplies a much more optimistic view of the arboreal monumental heritage than hitherto supposed. Lastly, it can be observed that the mere safeguard of an arboreal specimen, detached from a monitoring and enhancing program on its behalf does not guarantee it effective safeguard. These initial considerations confirm the validity of the choice of several different figureheads (volunteer associations, local administrators and professionals) concurring together to the inventory of remarkable trees. Furthermore, they underline the need of coordinating the work and of safeguarding at a more limited level than the regional one, that is at provincial level.

Conclusions The work so far carried out, on the basis of previous experiences, strongly supports the idea of creating a data-bank that would transcend being a simple cognitive reference, but which might become a tool in the valorization of the territory. To achieve this result, it is expedient to link all gathered information with the dynamics of the area they refer to, shifting from a merely impositive view of protection to a propositive one, thanks to which the identification and the filing of a monumental tree be translated in an undertaking of responsibility towards it, whereby any desire of safeguarding it be translated in an actual act of management and valorization.

Bibliography Assessorato all’Ambiente, Istituto Beni Culturali, Regione Emilia-Romagna (1991). Alberi monumentali dell’Emilia-Romagna. Censimenti e tutela. Bologna. Lonsdale D. (1999). Principles of Tree Hazard Assessment and Management. The Stationery Office, Norwich England. Morelli G. (1999). Il Censimento del verde del Comune di Ferrara. Estimo e Territorio, 9: 54-56. Nicolotti G., Della Beffa G., Mondino G. P., Palenzona M. (2003). Alberi monumentali in Piemonte. Presenze e avversità. Priuli & Verlucca editori, Ivrea (To). Read H. (2000). Veteran Trees: a guide to good management. English Nature, Peterborough Inghilterra. Tosetti T., Tovoli C. (ed.) (2002). Istituto per i beni artistici culturali e naturali della Regione Emilia Romagna. Giganti protetti gli alberi monumentali in Emilia Romagna. Editrici Compositori, Bologna. Torino, April 1st - 2 nd, 2004 129

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130 International Congress on the Trees of History Torino, April 1st - 2 nd, 2004 131

OBSERVATIONS ON THE EPIDEMIOLOGY OF CERATOCYSTIS FIMBRIATA F.SP. PLATANI ON PLANES IN A HISTORICAL LINE AND ATTEMPTS OF DISEASE CONTROL R. Martinis, P. Gonthier, F. Guglielmo, G. Nicolotti, A.M. Ferrara°, F. Tagliaferro°, E. Viotto° University of Torino, Di.Va.P.R.A. – Plant Pathology, Grugliasco (TO) - Italy °Forest and Environment Institute – I.P.L.A. S.p.A. Istituto per le Piante da Legno e l’Ambiente, Torino - Italy

Summary Four Platanus hybrida trees suddenly died in summer 2001 in a historical line at Serralunga di Crea (Al), North Western Italy. The death was due to the canker-stain disease caused by Ceratocystis fimbriata f.sp. platani. This paper describes the patterns of epidemics of Ceratocystis within the line. Since summer 2001, seven trees have been dying, and 12 trees were found to be infected by the pathogen in the xylem vessels either of the stem or of the roots. The role of root contacts, root anastomoses, and vectors for the spread of the disease within the line is discussed in the paper. Attempts to stem the epidemics by physical barriers were also made, and preliminary results are given.

Introduction Among the tree species growing in urban environments or parks, the planes (Platanus spp.) are commonly considered as good candidates to became monumental trees. Their relatively rapid growth, allowing to attain great dimensions, the shape of their crown, the morphology and colour of their bark, all accounts for such position. According to a recent census of trees in Piemont (North Western Italy), about ten percent of candidates to become monumental trees are planes (unpublished data). Planes are susceptible to wood decay fungi, root rot and leaf disease agents that may affect their vitality and integrity (Nicolotti et al. 2001; Marchetti, 2003; Nicolotti et al., 2004). Planes are also susceptible to a lethal fungal disease named canker-stain, and caused by Ceratocystis fimbriata f.sp. platani. Ceratocystis infects planes by spores or mycelial fragments on contaminated pruning tools, or through terracing machinery which causes damage to the roots (Vigouroux and Stojadinovic, 1990). It has also been shown that the fungus may spread from one tree to another via root grafts (Accordi, 1986). Despite these findings, the epidemiology of canker- stain disease still need investigations. Since the disease is extremely serious, protocols for the quarantine or the control are prescribed by the law in several European Countries. In Italy, according to the D.M. 17/04/ 1998, infected trees and any surrounding trees must be felled, and their wood must be incinerated or, alternatively, buried. Stumps should be extracted from the soil or killed by chemicals. The Italian protocol prescribes that all operations (i.e. felling, transport of infected wood) must be carried out avoiding sawdust dispersion in order to minimize the risk of new infections. As these approaches are quite onerous, any alternative strategies for disease control would be appreciable. The goals of this paper were: i) to describe the patterns of epidemics of canker-stain in a historical line, where no pruning (i.e. infection courts) has been occurring for decades, ii) to calculate the number of root contacts and anastomoses between neighboring trees, in order to assess the potential for tree to tree fungal spread, and iii) to check for the presence of C. fimbriata in roots of different diameter classes. Attempts to stem the epidemics by physical barriers within the line were also made, and preliminary results are given in the text.

Materials and method The present study was carried out in a historical line (Fig. 1) comprising 36 Platanus hybrida Brot., located at Serralunga di Crea (Al) (Tenuta Guazzaura), in the North Western Italy. Planes were about 160 years old, 30 m high, and their diameter at breast height (DBH) ranged between 70 to 160 cm. In summer 2001 four trees suddenly died. Diagnosis revealed the presence of C. fimbriata f.sp. platani inside the xylem vessels of dead trees. Such finding was interesting because i) the line was far away from any other plane formations, and ii) no pruning has been occurring for decades, so no apparent infection courts may explain how the fungus established there.

Patterns of epidemics of C. fimbriata f.sp. platani All trees were carefully mapped, and their general health conditions were monitored monthly since summer 2001. Trees displaying withering on crown, or simply sparse chlorotic 132 International Congress on the Trees of History foliage, were sampled, after bark removal, by extracting wood pieces of about 4 x 4x 3 cm by a sterilized scalpel from the edge of areas of xylem discoloration or at 1.3 m above ground. Wounds were treated with methyl thiophanate (Enovit Metil, Sipcam). The presence of C. fimbriata f.sp. platani was detected from collected samples either by incubating them in a moist chamber at 22° C in order to induce fruit bodies differentiation, or by extracting wood slivers (5-6 x 2-3 mm) and incubating them for 5 days onto 5 cm Petri dishes filled with Potato Dextrose Agar (PDA) (PDA 39g, streptomycine sufphate 0.150 mg, 1 l distilled water). The identification of fungal colonies was performed on the base of their macro- and microscopic features. All Ceratocystis isolates were subsequently subcultured and stored at 5° C on MEA (20 g glucose, 20 g malt extract, 2 g peptone, 20 g agar, 1 l distilled water).

Fig. 1- Historical line of Platanus hybrida at Serralunga di Crea (Al) (Tenuta Guazzaura)

Investigations on root contacts and anastomoses between neighbouring trees To study the potential for fungal spread via root contact or anastomoses, the root system was excavated between two neighbouring planes (Fig. 2) to check for the occurrence of root contacts or anastomoses between them. The two trees were 4,2 m far from each other. The excavation was about 60 cm depth. All roots, down to 0.5 cm diameter, were labelled and their diameter was measured each 10 cm.

Fig. 2- Excavation of the root system between two planes at Serralunga di Crea (Al) (Tenuta Guazzaura)

The following parameters related to the root system architecture were considered: i) mean diameter and number of roots at 70, 140, 210, 280, 350, 420 cm from the collar of trees, and ii) the total number of root contacts or root anastomoses between trees. Regression analysis was used to explore the relationships between the diameter of roots and their distance from the collar of the tree. To investigate for the relative importance of contacts vs anastomoses, the surface of root contacts and root anastomoses between trees was measured and compared.

Presence of C. fimbriata f.sp. platani in the roots The presence of C. fimbriata f.sp. platani was checked in roots of three planes. Excavations about 70 x 450 cm, and 160 cm depth, were made at about 3 m from the collar of trees. The Torino, April 1st - 2 nd, 2004 133 relative X Y coordinates of all roots visible on the profile were taken. A total of eighty roots were sampled by excising transversal disks. The presence of the pathogen on the collected samples was assessed as described above, or by checking for the presence of the typical clamydospores of C. fimbriata f.sp. platani inside xylem vessels. Transversal sections 30 mm thick were obtained by a microtome, and observations were performed under a light microscope at 400 x magnification.

Attempts to control the epidemics within the line Attempts to control the epidemics within the line were made by isolating uninfected from infected trees. For this purpose, a total of 40 m of trenches, each about 170 cm depth, were excavated in summer 2003. Broken roots on the walls of trenches were treated with methyl thiophanate. Root barriers (RootcontrolÒ) were buried into the trenches in order to prevent the negative effects of root growth (Fig. 3). The location of trenches is shown in Fig. 4.

Fig. 3- Trenches were made in order to separate asymptomatic from infected trees. Root barriers were buried into the trenches

Results Patterns of epidemics of C. fimbriata f.sp. platani Since summer 2001, 8 planes died (22%) in the line. C. fimbriata f.sp. platani has also been isolated from four additional planes, displaying withering on crown, or sparse chlorotic foliage. The location of trees within the line and their health conditions are shown in Fig. 4.

Fig. 4- Location of Platanus hybrida trees in the “Tenuta Guazzaura” line. The health conditions of trees, as specified in the legend, is up dated to October 2003. Numbers in bold characters are ID numbers of trees. For each tree, remaining numbers refer to the number of months, calculated from July 2001, when first symptoms of canker-stain and death occurred, respectively. The figure also shows the location of trenches and root barriers 134 International Congress on the Trees of History

Starting for the first infection center, comprising the four trees died in July 2001 (ID 12, 13, 14, 15), the disease spread to tree number 16, 17, and 11. A second infection center appeared at least one year later at about 50 m far, and comprises trees number 4, 1, 3, and 6. Tree number 24 displayed canker-stain symptoms starting from March 2003, and it died in July 2003. Trees have been dying four to ten months after showing first canker-stain symptoms.

Investigations on root contacts and anastomoses between neighboring trees The number of roots increased with the increasing of distance from the collar of trees. On the other hand, regression analysis showed a negative relationship between mean diameter of roots and distance from the collar (Fig. 5). The regression line indicates that at 5.37 m from the collar the diameter of roots equals 0.

Fig. 5- Regression analysis between mean diameter of plane roots and theirdistanc from the collar of trees

Three root anastomoses, and 1 root contact between the two trees were noticed. Total surface was 590 cm2 and 80 cm2 for anastomoses and contacts, respectively.

Presence of C. fimbriata f.sp. platani in roots Clamydospores of C. fimbriata f.sp. platani were found on roots laying from 10 cm to 170 cm depth (Fig. 6), and the fungus was successfully isolated from three roots.

Fig. 6- Clamydospores of Ceratocystis fimbriata f.sp. platani inside xylem vessels of plane trees

Roots of 2 out of 3 of the investigated trees were infected. The percentage of infected roots from these trees was 14% and 28%. Evaluating the percentage of infected roots for roots included in three diameter classes (0-1, 1-2, and 2-3 cm) (Fig. 7), the maximum percentage of infected roots resulted in the highest diameter class (50%). Torino, April 1st - 2 nd, 2004 135

fig. 7- Percentage of infected roots for each of three root diameter classes

Attempts to control the epidemics within the line A total of 64 m2 of RootcontrolÒ barriers were unrolled. Since the moment when such barriers were placed into trenches, no further death has been occurring. The time last since that moment is however not sufficient to assess the effectiveness of such control measure, and thus the monitoring is ongoing.

Discussion The Tenuta Guazzaura at Serralunga di Crea represents a good site to study the epidemiology of Ceratocystis fimbriata f.sp. platani for three reasons: 1- canker-stain has never been reported previously in the area, 2- the historical line is at least 3 km far from the nearest plane trees, and 3-, as mentioned above, no pruning has been occurring for decades there. Two different, but not mutually exclusive, hypothesis may be formulated in order to explain how the fungus came, presumably in 2001, into the line: by infected wood traveling on the Asti-Mortara railway, and by “long-distance” animal vectors. Both insects and rodents are potential agents of spread for Ceratocystis species (Crone and Bachelder, 1961; Panconesi and Nembi, 1978). Woodpecker drilling holes rather than galleries of insects were noticed through surveys performed with an elevator in the plane trunks and branches at Serralunga. The role of woodpeckers as vectors for Ceratocystis should thus be taken into account for future studies. Three Ceratocystis infection centers are recognizable in the Guazzaura historical line, comprising four trees, three trees, and one tree, respectively. Root contact and anastomoses are likely to have played, as they can do (Accordi, 1986), an important role in the “short- distance” spread of the disease within the infection centers. It has been shown that both root contacts and root anastomoses are frequent between neighboring trees at Serralunga. Moreover, the fungus was present into the xylem vessels of roots. The spread of the disease between infection centers cannot be explained in terms of tree to tree spread of the fungus via root grafts. According to the regression curve presented in this study, the probability of root system overlapping would be negligible if two trees are at 12 m or more far from each other, while infected trees comprised into different infection centers are at least 40 m far from one another. Animals might have playied an important role also in short and medium distance transmission of the disease. Although further investigations are needed, we propose that animals living in the soil (i.e. rodents, insects) rather than birds or flying insects may account for short and medium distance fungal spread at Serralunga. The greater importance of soilborne vs airborne infection in the line is supported by the following observations: i) infected trees died suddenly (4 to 10 months after first symptoms display), ii) xylem discoloration and cankers rarely developed on branches and, on the contrary, were commonly associated with basal portions of stems, and iii) in trees that became infected even though they were growing far away from any previously infected trees (i.e. tree n. 24), the fungus was isolated from the collar and not from the upper portions of the trees. Root barriers we used in the line, should be, at least in the theory, useful to prevent new infections in such a complex scenario, where the spread of the disease is likely originated either by root grafs / root contacts or by vectors living in the soil. We are now assessing the effectiveness of root barriers both in the laboratory and in the field, trough a periodic monitoring of the health status of trees. The Tenuta Guazzaura also represents a good site to test different methods to control unwanted spread of the fungus. For instance, we are 136 International Congress on the Trees of History now testing the effectiveness of the wood solarization and chemical treatments as possible methods to kill the pathogen into felled infected wood.

Acknowlegements This research has been supported by a grant of the Regione Piemonte – Assessorato Politiche per la Montagna, Foreste e Beni Ambientali. The authors are grateful to Dr Mario Palenzona for revising the text. We also thank Miss Ilenia Marafante, and the Servizio Fitosanitario Regionale for their help in performing field surveys.

Refefences Accordi M. S., 1986. Spread of Ceratocystis fimbriata f. platani through root anastomoses. Informatore Fitopatologico 36, 53-58. Crone L.J., Bachelder S., 1961. Insect transmission of canker stain fungus, Ceratocystis fimbriata f.sp. platani. Phytopathology 51, 576. Marchetti L., 2004. La difesa fitosanitaria delle piante ornamentali e forestali. Informatore Agrario 59, 89. Nicolotti G., Gonthier P., Cellerino G. P, 2001. Malattie delle principali specie arboree ornamentali. Informatore Fitopatologico 51, 21-26. Nicolotti G., Gonthier P., Pecollo D., 2004. Ecologia e grado di preferenza d’ospite dei funghi agenti di carie / I parte. Acer 1, 47-51. Panconesi A., Nembi V., 1978. La Ceratocystis fimbriata del platano: aspetti biologici e possibilità di lotta. Informatore Fitopatologico 28, 17-27. Vigouroux P.A., Stojadinovic B., 1990. Possibilités d’infection du platane par Ceratocystis fimbriata f. platani après contamination de l’eau où se développent des racines blessées. European Journal of Forest Pathology 20, 118-121. Torino, April 1st - 2 nd, 2004 137

DEFENSE OF THE MONUMENTAL TREES IN SPAIN B. Moya Sanchez Director of the Department of Conservation of Monumental Trees, Deputation de Valencia IMELSA – Spain

The juridical protection of the Natural, Historic, Cultural, Social patrimony such as the monumental trees and its outskirts, is the solution to guarantee their continuity and survival. Now the Spanish State has trasfered his Environment competence to the Autonomy- Communities; for this reason only they are responsable of this patrimony. But only few of the Autonomy-Communities have specific and efficienty giuridical protection on this matter so that ours monumental trees are threaten and subject to: - drastic pruning - innatural transplantation - urbanistic and industrial interest - agriculture trasformation of uncertain reason - arson - defect to phytosanitary control and conservation technique

With this desolating situation is our opinion that all Autonomy-communities should encrease their monumental trees protection by introducing the figure of the “Local interested tree”. In this way is more easy to protect end encrease the number of the monumental trees in local reality, and near to the people who lives in contat day by day, because they are ables to understand the social, cultural, historical importance of those trees as testimonial of their history and life. Most of our countries, for their environment and historical characteristic, has support the existence of large bio-diversity of autochthonous and allochthonous trees, that forms some parts of the woods, agricoltural cultivation and the ornamental vegetation of our cities. For this reason in the natural and urban ambient exist groups and botanic exemplaries with historical, cultural, social, scientific exceptional characteristics and with great value and local interest. This exemplary-list represent a irreplaceable trees patrimony that should be protected. Also they are point of interest with cultural, social, economics and educational function and point of start for diffuse the ambiental- sensibility , educational and the rispect of natural resorse with the promotion of sustainable development. The law 7/1985 “Reguardora de las Bases de Règimen Local” art. 25.2, par. d), e), f) e m) stated the rules for the protection of parks, gardens, historical and artistic patrimony, in order to declare directly protection to the trees, shurbs, palms or natural areas of Local interest that they consider important, without any others supervision or authorization. Based on this law, the Dipartiment of Monumental trees, Deputation of Valencia, has elaborate a specific “ Municipal Order for the Local Interest Trees Protection” . This Order is a list of rules where are defined, in a legal context: - the subject - the application - the validity - the interpretation - the system of catalogation - the rules for the trees and environment management - the specific techique for the conservation - the financing - the right and duty for the people and trees - the infraction and the sanction, according to the statal rules. This Municipal Order, adaptable to all Municipality, has been studied and adopted by a lot of Municipality of the comunity of Valencia, Andalusia, Castillia – La Mancha, Castilla Leon, Madrid, Extremandura, Andalusia. In this occasion we have a objective to diffuse this metodology of conservation with the aim of protection of the monumental trees with the partecipation of the people. The Dipartiment of Monumental Trees, Deputation of Valencia, is the only one recognized Dipartiment in Spain from more than ten years . During this time his has become a center of reference for the protection, management, recovery, promotion and valorization of the monumental trees in Spain. This experience has allowed us to understand and to face all the problems arised around the trees and their relation with the people. Recently, in last December, we have showed the first book that by a well defined and integral Spain cartography, describe our great biodiversity, his value and his state of preservation (J. Plumed, J. Moya and B. Moya, 2003) 138 International Congress on the Trees of History

MONUMENTAL TREES OF LIGURIA (NORTH-WESTERN ITALY) F. Russo(1), P. Du Jardin(1), G. Paola (2) (1) Regione Liguria, Dipartimento Agricoltura e Turismo, Servizio Politiche per l’Entroterra (2) Università di Genova, Dipartimento per lo Studio del Territorio e delle sue Risorse (DIPTERIS)

Introduction The Liguria Regional Council has issued a regional list of Monumental Trees (Liguria Regional Council Official Bulletin N° 15 of 10/04/2002, part II) according to Article 12 of Regional Law n° 4 of 22nd January 1999, “Norme in materia di foreste e di assetto idrogeologico” (Forestry and Geo-hydrological Regulations). The law regulates, for the first time in Liguria, the protection and recognition of the value of the region’s monumental trees, entering in a specific list “tree specimens, wherever rooted, that are of special naturalistic, environmental or historical and cultural interest for the Region”. It is important to point out that the protection afforded by this regional law covers not only particular forest trees but also agrarian and ornamental specimens. This is especially significant above all considering the history of Ligurian flora in general and in particular the urban flora. In this region, due to the morphology of the terrain and its specific climate, there is an unusual altitude-related distribution of forest species due to the extreme closeness of the mountains to the sea and to the ease with which plants originating from far-off countries become acclimatised.

Creation of the list of monumental trees of the liguria region The Regional Council has issued specific instructions for approving, keeping and up- dating the list of Monumental Trees of the Liguria Region. The work of searching for, conducting the census and describing the specimens started, in the first place, with the acquisition of existing material from Public Bodies, because both the Forestry Authorities and other public administrative bodies already kept lists of trees of special interest. A form was then prepared for reporting specimens, for use by local authorities (Provincial Councils, Mountain Communities, Municipal Councils, Park Authorities), associations of various types (environmental, cultural and so on), schools and scientific organisations and individuals. These forms can be used to provide information concerning either an isolated specimen or groups of plans believed to be of special interest. The survey methodology was then formulated, defining the assessment criteria and the parameters to be used. The task of identifying the specimens and collecting the data were entrusted to the Provincial Coordination Centres of the Forestry Corps. The first list of Monumental Trees of Liguria was approved on 26th February 2002, and subsequently up-dated (Official Bulletin part II n° 15 of 10/4/2002 and N° 20 of 14/5/2003). It contains 108 single specimens plus 11 rows or groups of plants.

Monumental trees of liguria The list of Monumental Trees includes very diverse plant typologies, bearing witness to the heterogeneous composition of the vegetation of Liguria. Alongside the commonest species, typical of the Ligurian woods, such as downy oaks, holm-oaks, beech trees and so on, and plants proper to the region’s rural heritage such as chestnut and olive trees, there are also ornamental and exotic species, situated mainly in urban environments, such as several species of palms. The most widespread indigenous monumental trees were found to be Quercus ilex L. (with 12 specimens listed), Quercus pubescens Willd. and Fagus sylvatica L. (11 specimens each). Other species of evergreen and deciduous oaks are also listed ( Quercus suber L., Quercus crenata Lam., Quercus petraea Matt.), although the number of specimens is decidedly lower, while there is no specimen of Quercus cerris, well represented nowadays above all in the eastern part of the region and mentioned extensively in Medieval and later documents also referred to central and western Liguria. These presences fit in well with the vegetation cover of the region and are, after all, the living memory of the vegetation of past centuries. The holm-oak is dominant along the Tyrrhenian coastal strip, thermophilous and mesophilous oak woods higher up on the slopes facing both the coast and towards the Po valley, and beech woods at yet higher altitudes on the Ligurian Apennines. The Alpine part of the mountains of western Liguria features the presence on the list of Larix decidua Mill. and Abies Alba Mill. The list also indicates indigenous species not frequently encountered nowadays in our woods, such as Taxus baccata L. (3 specimens in the central part of the region) and Tilia platyphyllos Scop. Two species proper to the region’s rural heritage occupy a special place: Olea europaea L. and Castanea sativa Miller. Only a few specimens of these Torino, April 1st - 2 nd, 2004 139 species are listed (4 and 5 respectively), in spite of the fact that they are both extremely widespread in Liguria and well-known for their longevity. With reference to the olive-tree, it is possible that the current scarcity of majestic specimens is due to the way in which it is managed on the terraced slopes of the Mediterranean coastal strip of Liguria paying the main attention to the best yield. As far as concerns the chestnut, the scarcity of veteran specimens can be attributed to the changes introduced in the management of chestnut woods following the arrival of chestnut ink and bark diseases. Exotic species play a considerable part in the overview of monumental trees in Liguria: all of 22 species indicated on the list do not belong to our own flora. Pinus pinea L. has also been included in this list, since it is not spontaneous in this region. As many as 10 pine-nut producing pines have been considered monumental, and almost all of these have an important role in the landscape. The only other pine on the list is a specimen of Pinus canariensis Smith, while there is no mention at all of either Pinus pinaster or Pinus halepensis, both extremely widespread nowadays in Ligurian woods. Although the highest trees in Liguria are above all exotic species, some indigenous species such as the beech find conditions enabling optimum development on our Apennines: Liriodendron tulipifera L. reaches 40 metres, Eucaliptus globulus Labill. 37 m, Fagus sylvatica L. 37 m, Pinus canariensis Smith 36 m, Cedrus atlantica Endl. 35 m, Picea excelsa Link. 34 m, Abies nordmanniana Spach. 32 m, Platanus orientalis L. 32 m, Cedrus libani A. Richard 30 m, Cupressus sempervirens L. 30 m, Populus nigra L. 30 m, Sequoia sempervirens Endl 30 m, Tilia platyphyllos Scop. 30 m. Some exotic species have become typical of the Ligurian landscape, in particular along the coast, such as the araucarias of Bordighera (Araucaria excelsa R.BR.) and palm trees. There are three species of palm on the list: Jubaea chilensis H.B.K., Phoenix reclinata Jacq., and Washingtonia filifera Wendl., the first two being rare and the last extremely common. The species of palms most common along the coast, Phoenix dactylifera and Phoenix canariensis, are not listed at all. Special links have developed over the centuries between trees and religious buildings. Indeed, many monumental trees grow near chapels, churches, abbeys or shrines. In these cases it can be said that the aesthetic and landscape value of the architectural complex is enhanced also by the presence of these living monuments of nature. The species most commonly found close to religious buildings are the cypress, found near the shrine of the Madonna di Reggio in Vernazza (La Spezia) or that of the Madonna di Soviore in Monterosso (La Spezia) and again near Borzone Abbey in Borzonasca (Genoa). Some of these trees are several centuries old, this being a peculiar feature of cypresses, which at times are of the same age as the nearby religious buildings. Another species often found near churches is the holm-oak, of which there are handsome specimens near the shrine of Our Lady of Lampedusa in the municipality of Castellaro (Imperia), near the churches of Santa Giulia in Lavagna (Genoa), of Santa Maria del Campo in Rapallo (Genoa), at the Montallegro shrine in Rapallo and again near the shrines of the Madonna di Reggio in Vernazza (La Spezia) and of the Madonna di Soviore in Monterosso (La Spezia). There are, however, also some less common species, such as the horse chestnut in front of the churches of Sant’ Agostino and of San Bernardino in Triora (Imperia), or the nettle- tree in Piazza San Michele in Diano Borello (IM). The maintenance and survival of these trees, now admired by us as monumental, may have been facilitated by various different situations. Specimens growing in anthropic environments, near religious buildings, in the gardens of stately homes, in public places and on squares, as well as those close to houses in rural environments enjoy the constant attention of people, who generally develop a special bond, often of affection, with them. As far as concerns large old trees growing in woods or fields, it can be supposed that they were very often maintained as signs for marking borders between estates, communities and sometimes even between states. This list of monumental trees of the Liguria Region is not exhaustive. It is intended, rather, as a starting point for improving knowledge of the vegetable wealth of the region and as a stimulus to encourage its careful management.

Bibliography PAOLA G., CICILIOT F., 1998 - Woodland management and timber supply for ship masts in eigtheenth century western Liguria (Italy), in Watkins C., European Woods and Forests: Studies in Cultural History, pp. 157-163. CAB International, Oxon - New York. PAOLA G., MINUTO L., 1994 - Indagine floristica sulle specie ornamentali nel verde pubblico della fascia costiera franco ligure. Giorn. Bot. Ital. 128: 381. 140 International Congress on the Trees of History

PAOLA G., MINUTO L., 1998 – Prime note sulle Palmae della Liguria. Medemia 1: 15-21, 1997. RUSSO F., DU JARDIN P., BELTRAMI F., RUZZEDDU G., PAOLA G., 2003 – Alberi di Liguria, monumenti viventi della natura. Regione Liguria, Assessorato alle Politiche per l’Agricoltura e l’Entroterra, Servizio Politiche per l’Entroterra, Assessorato al Territorio e Ambiente, Ufficio Parchi e Aree Protette, Corpo Forestale dello Stato Liguria, catalogo dei beni naturali n. 4, Erga Edizioni, Genova

Appendix Torino, April 1st - 2 nd, 2004 141 142 International Congress on the Trees of History Torino, April 1st - 2 nd, 2004 143 144 International Congress on the Trees of History

ON THE HEALTH OF A MONUMENTAL TREE OF FICUS MACROPHYLLA DESF. EX PERS. SUBSP. COLUMNARIS (C. MOORE) P. S. GREEN (SIN. = FICUS MAGNOLIOIDES BORZÌ VAR. MAGNOLIOIDES) IN PALERMO L. Torta, G. Zoida, S. Burruano Dipartimento S.En.Fi.Mi.Zo., Sezione di Patologia vegetale e Microbiologia agraria, Università degli Studi - Palermo

Introduction Some monumental trees of Ficus macrophylla Desf. ex Pers. subsp. columnaris (C. Moore) P. S. Green (sin. = Ficus magnolioides Borzì var. magnolioides; Fici and Raimondo, 1996) are present in many parks and gardens of Palermo; the species, belonging to the family of the Moraceae, originating from Australia, has been introduced into Europe in the early 19th, via Palermo (Botanical Garden), where they become estabilished. Currently, some secular monumental exemplars of stately dimensions (over 30 m of height and 40 of diameter of leafage), and good health conditions characterize the parks of Giardino Garibaldi (Fig. 1a, b), Villa Malfitano (Fig. 2), and Botanical Garden; nevertheless, since over one decade, on both young and old neighboring trees to the aforesaid exemplars, a slow but progressive decay was noted. Particularly, the plants initially show a slight apical defoliation with chlorosis and leaves small, evolving in an apical drying that can affect one or more branches, or the whole crown. Moreover, wood rot (white and brown, as well) in the trunk and in the principal branches are evident, and, at the same time, more or less widespread cancerous lesions, often with lactiferous flow, are present too. The first research on the etiology of such alteration and on the possible contamination from the damaged plants to the healthy ones, didn’t give any definite results, inducing to hypothesize the physiological origin of the decaying (Torta and Mondello, 1997). Recently, the decaying has also been noted in some ficus in the park of Villa Malfitano where is present one of the most interesting monumental specimen, together with secular and young trees. Therefore, a preliminary study has been started on three different trees: the first, the monumental specimen, showing occasionally in some branches an initial chlorosis, apical defoliation, and slight transparence in parts of the crown; the second tree, showing apical drying widespread to more branches (Fig.3a), and typical cancers; the last one, very damaged, with evident drying on branches and on the whole crown (Fig.3b), showing defoliation, frequent cancerous lesions (Fig. 4a) with red- brownish underlying tissues (Fig. 4b), and abundant lactiferous flow. Furthermore, in the first and third trees there were, both on the trunk and along the principal branches, evident white or brown wood rot. In this first step, our observations were aimed to determine the fungal community associated to the altered organs, pointing out the species that could be correlated to the lesions.

The Park of Villa Malfitano The Park of Villa Malfitano (belonging today to the Foundation Whitaker), was founded in 1886, for Giuseppe Whitaker’s will. Following the canons of the “Romantic Garden”, a rare collection of exotic plants, which most of them are still living, has been planted inside the park. The park, that occupies an area of over 4 Ha, today hosts about 250 species, most tropical and sub-tropical and some Mediterranean taxa such as leccio (Quercus ilex), tino (Fliburnum tinus) and colonies of dwarf palm (Chamaerops humilis). The peculiarity of the park, however, is the monumental specimen of F. macrophylla subsp. columnaris, planted in late 19th and today take an area of about 1.000 m2 (Raimondo, 1995)

Material and methods A branch showing different symptomatologies (wood rot, cancerous lesions, lactiferous flows, desiccation of branches, defoliation, leaves small and chlorosis) has been chosen and cut in several portions, for each tree. From each of these portions, some samples were taken, bagged in polyethylene sacks, and brought to the laboratory. The samples, after preliminary washing by tap water, were used for preparation of moist chambers and techniques of isolation. In this last case, the surface of samples have been previously sterilized, by immersion in aqueous solution of sodium hypochlorite at 5% for 5 minutes or by rapid flaming. Fragments of woody tissues in the marginal zone of the lesions, have been taken in sterile way, and put in Petri dishes containing universal medium (PDA); both these, and the moist chambers, were incubated at 21 °C. The pure cultures were identified on the base of their macro- and microscopic features, using taxonomic keys and atlas of identification (Barnett, 1965; Hawksworth et al., 1995). Torino, April 1st - 2 nd, 2004 145

Results and discussions The laboratory analysis showed a certain biodiversity inside the fungal community related to the different symptomatologies, as reported in TAB 1. Particularly, colonies of Rhizoctonia spp., Gliocladium spp., Alternaria spp., Trichoderma spp., Stemphylium spp., etc, ubiquitary saprotrophyc microorganisms or weak pathogens, grown both in moist chambers and on PDA. Colonies belonging to genus Cytosporella (Fig. 5) were the most frequently isolated: numerous strains, in fact, were constantly connected to the apical drying and, on the second tree, to all the different symptomatologies. Since some species of Cytosporella are known like primary or secondary agents of dryings of the branches on different forest trees, like pine (C. damnosa; Goidanich, 1964) and poplar (C. populi; Stefanov et al., 1961), it is possible to consider such fungus implicated in manifestation of the alteration. Relatively to the most declining specimen sample inside fungal community of the cancerous lesions of the xylematic necrosis and wood rot, have recurrently revealed the presence of strains of Verticillium spp. and Fusarium spp., fungal genera well-known as tracheomycotic agents. Further pathogenecity tests on healthy plants will allow to define the possible role of Cytosporella spp. on the manifestation of the apical drying of F. magnioloides subsp. columnaris and, in particular, of the monumental tree. The observations on the fungal community associated to the different symptomatologies, compared to results obtained from the most declining specimens, could give useful indications on the interaction between the most recurrent taxa and the development of the decline.

Tab.1: Fungal genera associated to the lesions of the three specimens of Ficus macrophylla subsp. columnaris (Villa Malfitano, PA)

ab

Fig. 1 - An asymptomatic monumental tree of F. macrophylla ssp. columnaris in Giardino Garibaldi in Palermo: a) crown; b)trunk with columnar and tabular roots 146 International Congress on the Trees of History

Fig. 2 - The monumental tree of F. macrophylla ssp. columnaris in Villa Malfitano (specimen 1), showing a slight transparence in the crown.

a b

Fig. 3 - Different stages of the decline of F. macrophylla ssp. columnaris: a) apical drying widespread in some branches; b)evident drying of the whole crown

ab

Fig. 4 - Xylematic alterations detected during the observations: a)cancers; b) reddish, brownish, and necrosis of the tissues Torino, April 1st - 2 nd, 2004 147

Fig. 5 - Pure colony of Cytosporella sp., isolated from apical drying of F. macrophylla ssp. columnaris; in the frame, section of a pycnidia formed in black, irregular stroma (bar = 50 µm)

References Barnett, 1965: Illustrated Genera of Imperfect Fungi. Burgess Publishing Company, Minneapolis; Fici S., Raimondo F.M., 1996: On the real identity of Ficus magniolioides. Curtis’s Botanical Magazine, 13, 105-107; Hawksworth D.L., Kirk P.M., Sutton B.C., Pegler D.N., 1995: Ainsworth & Bisby’s Dictionary of the fungi, 8th ed. International Mycological Institute, CAB International, University Press, Wallingford, UK; Goidanich G., 1964: Manuale di Patologia vegetale, Vol. II. Edagricole, Bologna, 928; Raimondo F.M., 1995: The Garden of Villa Malfitano, Giuseppe Witaker’s Foundation, Palermo; Stefanov D., Zashev B., Tsanova Mme P. 1961: Brown sap-flow and some fungi on stems and branches of Poplars in the People’s Repubblic of Bulgaria. Nauch. Trud. vissh. Lesotekh. Inst., Sofiya, 9, 143-156. In R.A.M. 1963, 42, 577; Torta L., Mondello V., 1997: Osservazioni sullo stato fitosanitario di Ficus magnolioides Borzì var. magnolioides nella città di Palermo. Atti III Congresso Europeo di Arboricoltura; II Giornate Meranesi dell’Albero. Merano, 14-16/05/1997. 148 International Congress on the Trees of History

THE IMPACT OF RESISTOGRAPH ON TREE DECAY A. Toussaint, JP. Baudoin, B. Campanella, Pr. R. Paul Unit of Tropical crop husbandry and Horticulture, FUSAGx Laboratory for environmental Toxicology, FUSAGx

Acknowledgements This work was founded by the Ministry of the Walloon Region (Belgium), G.D. for Natural Resources and Environment and G.D. for Employment and Training. We also thank F.N.R.S. for its financial contribution

Summary People in charge of ‘green heritage are even more frequently asked for objective information about future of street or park trees showing signs of decay. Generally, these are needed for insurance or security reasons. Resistograph is one of the most commonly used tools in establishing rapid diagnostic. It is easy to use, affordable for most of public authorities and resistogram is a visual proof of the analyses. Nevertheless, in some cases, this tool may induce side effects that are not negligible. This study on Tilia sp. shows a four fold increased spread of heart rot in the wood crossed by the resistograph needle. If lignolytic fungi attack trees, one can fear a faster disease spread inside trunk and/or branches but also a possible transport from tree to tree if needles are not properly disinfected. As a consequence, this invasive technique has to be used only when necessary, and not systematically.

Introduction In 1992, 280 roadside trees (Tilia cordata and T. europea) were drastically pruned. During the next ten years, numerous sprouts were produced (Toussaint et al. 2002). New intervention was necessary to avoid that natural selection led to branch fall. In 2002, experimentation was started to test the efficiency of several soil treatments in increasing vitality, but also to assess the problems of wounds and cavities. Numerous 10 years old wounds are now presenting rots and cavities. Another important problem is the infection of old injuries by decay fungi (Ganoderma sp. and Ustulina sp.). In the frame of stability diagnostic, resistograph was used to precisely measure the extension of decay. People in charge of ‘green heritage’ are even more frequently asked for objective information about future of street or park trees showing signs of decay. Generally, these are needed for insurance or security reasons. Resistograph is one of the most commonly used tools in establishing rapid diagnostic. In our study, diagnostic was realized for urban authorities and it was recommended to cut 3 trees down for security reasons. After this, trees were divided in sections and the extent of decay was observed to confirm diagnostic.

Results Decaying tree was firstly pointed out following the VTA method (Betghe and Mattheck 1993). Three clear symptoms were: •The crown heterogeneity. In addition to the severe crown disorganization due to over pruning, this tree showed one half of dying branches (strongly reduced foliage, small and chlorotic leaves when present). •The progressive decay of bark at trunk base. •The presence of heart rot fruit body (Ganoderma sp) at trunk base and 120 cm. At this level, an old bark wound (15 x 25 cm) has not been overlaid by wound wood.

Six measurements were realized with Resistograph IML-Resi F-400 at trunk base and 120 cm. Data were processed according to a method described previously (Campanella et al. 2003). Following the localization of weakened zones in the 6 directions, an estimation of fungus extension in the trunk was presented to local authorities to traduce the risk associated with this tree (figure 1). After tree cutting down, two major observations were made: • Extension of the discolored zone and the fungus is more important than postulated after resistograph measurements. It is particularly true in the direction of measurements 1,2 and 3. This could be partly due to heart rot progress during 4 months. Data processing could also be improved. Particularly, it would be important to better distinguish weakened wood limits. Moreover, fungus activity is not directly traduced by a decrease in wood density. Torino, April 1st - 2 nd, 2004 149

• Impact of measurements 2 and 3 are visible. Locally, where new injuries occurred, the discolored zone is more extended (figure 2).

Figure 1: scheme of 6 measurements with resistograph Figure 2: discolored zone following at trunk base (—%: correct density; ---: weakened or resistograph measurement in amorphous wood). Fungi fruit bodies are shown in transversal (above) black, estimated decaying zone in pale gray and the and longitudinal (below) section observed decaying zone in dark gray

Two wood samples were taken to describe the extension of reaction zone in the 3 dimensions. Polyphenol accumulation was also visible under microscope. This accumulation occurs in vessels as well as parenchymatic rays. Wood chips were taken, discolored with oxygen peroxide and treated with acidic fushine to stain fungal hyphae. No trace of fungus was identified in the discolored zone.

Table 1 : dimensions of reaction zones in the two samples

Dimensions of the neo-formed reaction zone are slightly different between the two samples (table 1). Compartmentalization is more efficient in the tangential direction (e) than in the longitudinal one (a, c), which is consistent with CODIT model (Shigo, 1989). In this particular case, the extent of reaction zone is 4 fold increased after drilling. It must also be mentioned that wall 4 of the CODIT model has been broken by the fungus. No wall was detected by resistograph measurements.

Conclusion In this particular case, resistograph was useful to complete diagnostic and demonstrate the importance of decay. Nevertheless, intrusive measurement will have consequences on fungus development. After 4 months, reaction zone has normally developed around the hole. Even if fungus has not been detected in the hole, its radial growth will certainly be easier. It is then important to know that the use of resistograph could accelerate the process of wood decay. Moreover, the even more common practice of systematic resistograph use should be avoided as some trees showing cavities could be remained in place if the decay was efficiently contained. Systematic measurements realized in cities could accelerate the decay of street 150 International Congress on the Trees of History trees. These observations confirm suspected phenomenon, but it is, as far as we know, the first time that it is quantified in lime tree. Another well-recognized risk is the fungus transport from trees to trees if needles aren’t disinfected. Current experimentations are designed to measure the progressive development of fungi in the hole and tree reaction after drilling (evolution of reaction zone with time and kinetic of wound cover). These observations are realized mainly on lime trees infected by various rots.

References Betghe, K. and C. Mattheck (1993). VTA - Visual Tree defect Assessment and related testing methods. 9th Int. Meet. Non-Destructive Testing., Madison, USA. Campanella, B., A. Toussaint, et al. (2003). “Amélioration de l’interprétation des données fournies par le résistographe pour la gestion d’arbres d’alignement. 1 : le cas du tilleul.” Arbres et Sciences 9. Shigo, A. (1989). Tree pruning: a worldwide photo guide for the proper pruning of trees. Durham, A. Shigo, ed., 187p. Toussaint, A., V. Kervyn, et al. (2002). “Analyse de l’impact physiologique et économique de l’élagage des arbres d’alignement en port libre.” Biotechnol. Agron. Soc. Environ. 6(2): 99-107. Regioni 152 International Congress on The Trees of History Torino, April 1st - 2 nd, 2004 153

IL VALORE STORICO, CULTURALE E PAESAGGISTICO DEGLI ALBERI GLI ALBERI MONUMENTALI B. Sara’

Dovendo intervenire in un convegno che tratta in modo approfondito e scientifico i temi e le problematiche degli alberi, alla presenza di molti ed illustri competenti in materia, credo sia necessario, innanzi tutto, confessare di non sentirmi e non essere un “addetto ai lavori” nonostante gli uffici del Settore di cui sono responsabile si occupino anche di Alberi Monumentali. Avrei delle grosse difficoltà a parlare scientificamente o quantomeno come esperto di alberi. Io mi ritengo, innanzitutto, un “ utente” degli alberi, uno dei tanti che dagli alberi traggono sensazioni, emozioni, stati d’animo, direi, in ultima analisi, giovamento. Chi, d’altro canto, oltre a usufruire dei benefici effetti prodotti dagli alberi, sulle qualità fisiche dell’ambiente in cui vive, non prova, anche se molte volte a livello inconscio, piacevoli sensazioni di pace, di tranquillità, di antica maestosità a seconda che si soffermi sotto un gruppo di alberi o si trovi in un bosco ? Chi non si stupisce della loro forza vitale quando gli capita di vedere alberi che tentano di svilupparsi e di crescere nelle situazioni più ostili, tra le crepe di un muro o annegati in lastricati di cemento ? Esiste poi un aspetto degli alberi che mi affascina particolarmente, probabilmente per deformazione professionale: la loro “architettura”. Suscita sempre un grande stupore soffermarsi ad ammirare l’architettura degli alberi ovviamente, a maggior ragione, se si tratta di alberi di più antico impianto e di più rilevanti dimensioni, architettura a volte imponente, severa, a volte leggera, elegante, che pur avendo ragioni assolutamente scientifiche raggiunge, in molti casi perfezioni e ritmi che sembrano rigorosamente studiati per ottenere, con ricercate simmetrie o volute casualità, risultati estetici di grande effetto. Sempre per una deformazione professionale, dovuta ai miei trascorsi di urbanista, vorrei ricordare anche l’importanza degli alberi e delle alberate nel disegno della città. Basti pensare a quello che rappresentano nel contesto cittadino i viali, soprattutto i viali storici, monumentali (come spesso si trovano nelle città europee, non ultima Torino che è caratterizzata da numerosi viali monumentali le cui alberature, per altro, sono già vincolate) sia che essi attraversino il centro urbano o che lo perimetrino. Ben difficilmente il viale è solo un luogo di transito veicolare. In genere il viale è anche un luogo di passeggio, di sosta, di incontro, di socializzazione. Un luogo di cui hanno usufruito intere generazioni, che appartiene alla memoria collettiva, che entra a far parte della storia della città, un luogo che non solo evoca ricordi negli abitanti ma che caratterizza la città nella memoria dei visitatori. A questo proposito mi pare di poter affermare, dopo aver esaminato numerosi Piani Regolatori di città di ogni dimensione, che oggi, troppo spesso ci si dimentica della insostituibile funzione degli alberi. Al di là di insignificanti giardinetti, nati più dalla necessità di assolvere obblighi legislativi che non da un preciso disegno urbano, ben difficilmente nei contesti urbani di nuova edificazione o di nuovo impianto sono stati previsti o vengono previsti spazi verdi con significative masse arboree o, tanto meno, viali che, potendosi chiamare tali e per lunghezza e per caratteristiche, ne connotino, oggi e negli anni futuri, l’immagine. Tralasciando altre possibili riflessioni, credo che molte volte la presenza degli alberi, quali elementi del paesaggio non solo agricolo ma anche urbano, e, in ultima analisi, la loro insostituibile funzione per migliorare la qualità della vita sia decisamente sottovalutata; anche perché la fretta e l’abitudine sovente ci impediscono di percepirne appieno e di valorizzarne la silenziosa presenza. È quindi necessario che si parli di alberi. Ed è in questo senso che mi sembrano particolarmente utili le azioni che ha inteso portare avanti la Regione Piemonte ed in particolare l’Assessorato alle Politiche per la Montagna, Foreste e Beni Ambientali: sia promuovendo il dibattito scientifico e lo scambio di esperienze, soprattutto sul tema della conservazione e della cura del patrimonio arboreo esistente, sia producendo e distribuendo materiale divulgativo di più immediata e generale comprensione al fine di richiamare l’attenzione degli abitanti del Piemonte ed in particolare dei ragazzi (vedasi il CD “Alberi Monumentali del Piemonte”) sulle tematiche degli alberi e sugli aspetti storici e sociali che ad essi possono essere collegati. Infatti ritengo importante, da un lato, suscitare l’interesse ed educare i cittadini a riconoscere l’importanza degli alberi, incominciando proprio da quelli che, dal punto di vista storico e/o paesaggistico, costituiscono, per così dire, gli episodi più significativi presenti sul 154 International Congress on The Trees of History territorio regionale e, d’altro lato, adottare strumenti per la loro tutela affinché quest’ultima non venga interpretata come un’imposizione calata dell’alto ma divenga invece un’esigenza condivisa, frutto di un pensiero comune che identifica l’oggetto della tutela come un patrimonio dell’intera collettività. In questo senso è stata emanata ed è gestita la Legge Regionale n° 50 del 3 aprile 1995 che promuove “il censimento, la tutela e la valorizzazione di alberi, filari e alberate di alto pregio naturalistico e storico del Piemonte” ovvero la Legge sui, così detti, “Alberi Monumentali”., Volendo illustrare, per sommi capi, i contenuti e le azioni che la Legge in questione intende attuare è necessario, innanzi tutto, chiarire cosa si intenda per Alberi Monumentali:

· gli alberi che per età o dimensioni possono essere considerati come esempi unici di maestosità o longevità; · gli alberi che hanno un preciso riferimento ad eventi o memorie rilevanti dal punto di vista storico o culturale; · filari e alberate di particolare pregio paesaggistico, monumentale, storico-culturale, comprese quelle inserite nei centri urbani.

Partendo dalla giusta considerazione che un’effettiva tutela, quindi una tutela mirata e non generica, debba necessariamente basarsi su di una puntuale conoscenza dei beni da salvaguardare, la Legge 50/95 promuove, innanzi tutto, il censimento degli Alberi Monumentali, invitando, in un’ottica di massima partecipazione, i Cittadini, gli Organi e gli Enti Pubblici o le Associazioni a segnalare l’esistenza di tutti quegli esemplari che per le loro peculiarità potrebbero essere definiti tali. Tale censimento è stato di fatto avviato nel settembre 1999 con l’invio, a tutti i Comuni, alle Associazioni interessate e agli Enti preposti alla tutela, di una circolare con la quale li si invitava ad attivarsi per effettuare le segnalazioni e nello stesso tempo li si informava della avvenuta costituzione della “Commissione Tecnica per la tutela e la valorizzazione degli alberi, filari ed alberate monumentali” prevista dalla Legge in questione. La Commissione è presieduta dall’Assessore ai Beni Ambientali e Paesaggistici (attualmente è quindi presieduta dall’Assessore Roberto Vaglio) e di essa fanno parte l’Assessore ai Beni Culturali o un suo rappresentante, un rappresentante dell’IPLA (Istituto per le Piante da Legno e l’Ambiente), un rappresentante della Soprintendenza ai Beni Ambientali ed Archeologici del Piemonte, un rappresentante del Corpo Forestale dello Stato e un Rappresentante della Facoltà di Scienze Forestali dell’Università di Torino. Successivamente, la Giunta Regionale ha ancora adottato la metodologia di rilevazione e la Scheda di identificazione necessarie per predisporre il censimento, elaborate dalla Commissione. Su tali schede vengono riportati, non solo la descrizione dell’albero o degli alberi segnalati, le loro caratteristiche fisiche, il loro stato di salute, ma anche notizie sulla loro storia, sul loro rapporto con l’ambiente e con la cultura locale. Vorrei aprire una parentesi per sottolineare ancora quest’aspetto che mi pare particolarmente significativo ovvero la volontà del legislatore e quindi dell’Assessorato di tutelare l’ “oggetto albero” non solo per il suo interesse botanico, ma anche perché parte integrante di quel patrimonio d’elementi che caratterizzano un luogo dal punto di vista paesaggistico e che ne costituiscono le radici storiche e culturali. Le proposte di vincolo vengono quindi trasmesse alla Commissione Alberi Monumentali che le valuta e decide con parere obbligatorio e vincolante quali, tra gli alberi segnalati, abbiano le caratteristiche per essere inclusi nell’elenco degli alberi monumentali e, come tali, essere oggetto di vincolo. A questo punto inizia l’iter procedurale che vede impegnati gli Uffici del Settore Beni Ambientali (convocazione dei Sindaci dei comuni interessati, atti di deposito, pubblicazione e pubblicizzazione, raccolta osservazioni, ecc ) che si concludono con la formalizzazione del vincolo da parte della Giunta Regionale, iter procedurale che come tutte quelli preordinati all’imposizione di vincoli, non è né breve né facile e che si conclude con le notifiche ai possessori e l’affissione del provvedimento all’Albo Pretorio. Altra particolarità importante della Legge è che prevede che vengano erogati contributi per la cura ordinaria e straordinaria degli alberi considerati monumentali e che la Giunta Regionale possa promuovere iniziative per la loro valorizzazione. A tal fine la Giunta Regionale, in ogni esercizio finanziario, dispone l’assegnazione al Settore Beni Ambientali di un budget di spesa per la promozione, il finanziamento degli interventi sostitutivi e per la valorizzazione dei siti arborei. Questo Budget si aggira mediamente, su base annua e a seconda delle effettive disponibilità , intorno ai 250/500.000 Euro. A questo proposito ritengo utile segnalare che la Regione Piemonte ha ritenuto di intervenire Torino, April 1st - 2 nd, 2004 155 direttamente e con propri mezzi economici e professionali nell’esecuzione degli interventi di cura delle alberature sollevando quindi i comuni o i privati da qualsiasi tipo di defatigante procedura burocratica nell’assegnazione degli incarichi e di responsabilità nella fase operativa potendo la Regione stessa garantire l’alta professionalità degli operatori tramite l’affidamento degli incarichi all’Istituto per le Piante da Legno e l’Ambiente e all’Università sulla base di un programma annuale d’intervento. Il 30.12.2002 si è finalmente giunti all’approvazione del primo elenco degli alberi monumentali costituito da cinque esemplari. Attualmente sono in fase di completamento le procedure per il riconoscimento di altri diciotto alberi monumentali mentre per cinque alberi è stato affidato un incarico al corpo Forestale dello Stato per l’acquisizione della documentazione tecnica necessaria per iniziare le procedure di vincolo. Vorrei citarne almeno alcuni per dare un’idea di come tali alberi siano esemplari che suscitano stupore per le loro caratteristiche, siano di antica o antichissima origine e abbiano, come si diceva prima, attraversato intere generazioni entrando, a pieno titolo, nella storia e nelle leggende dei paesi in cui sono collocati:

- il “Frassino di Moncenisio”, posto sulla Piazza Parrocchiale del paese, la cui età è valutata in circa 500 anni, simbolo della montagna e dalla sua storia;. - il “Tiglio di Macugnaga” che potrebbe avere addirittura dai 685 ai 887 anni se, come vuole la tradizione, è coevo della vicina chiesa. Sotto la sua chioma si dice si radunasse un tempo il consiglio comunale; - il “Platano di Napoleone” posto lungo la strada che da Alessandria portava a Marengo e sotto il quale, si dice, si sia soffermato Napoleone nel giugno del 1800 dopo la famosa battaglia di Marengo; - l’imponente Cedro di Montalenghe, di circa 13 mt. di circonferenza e 36 mt. di altezza, la cui età si aggira intorno ai 350 anni e che risulta essere uno dei più grandi e vecchi cedri d’Italia.(vincolo in itinere) - il bellissimo “Tasso di Cavandone”situato nell’omonima frazione di Pallanza, di 3,6 mt. di circonferenza e 26 mt. di altezza, che con i suoi 450 anni e il tronco contorto e possente è una vera opera d’arte della natura.

Da questi pochi esempi, è evidente quindi l’interesse scientifico, storico e culturale che gli alberi monumentali suscitano. Ma occorre dire che a questi interessi se ne possa aggiungere un altro: quello turistico. Quest’ultimo, se opportunamente incentivato e sfruttato potrebbe costituire per alcuni dei Comuni interessati un valore aggiunto non trascurabile, sull’esempio, per altro, di quanto accade in altre nazioni a noi vicine nelle quali episodi anche meno significativi vengono regolarmente segnalati ed enfatizzati su tutte le guide turistiche. Ritornando un attimo al tema più generale dell’utilizzo degli alberi e delle alberature, mi sia concesso concludere con una brevissima annotazione connessa al mio attuale incarico nel Settore Gestione Beni Ambientali, Settore che si occupa di verificare il corretto inserimento ambientale degli interventi che ricadono in ambiti vincolati e nei cui uffici quindi transitano quotidianamente progetti di ogni genere. Gli alberi, in molti casi, possono avere un’importanza assolutamente non trascurabile nella progettazione; gli alberi, se attentamente “progettati” sia per posizionamento che per tipo, si integrano nel progetto stesso, lo completano, lo valorizzano e, per così dire, lo arredano. Purtroppo, questa grossa potenzialità non sempre è percepita correttamente dai progettisti. Non ultimo, gli alberi sono una potente medicina per l’architettura quando l’architettura è malata. Laddove il prodotto architettonico è discutibile, né esistono ragionevoli speranze di migliorarlo, spesso non rimane che un’ultima soluzione: prescrivere la messa a dimora di gruppi o filari di alberi che con la loro naturale bellezza riescono, quasi a stendere un velo sui peccati dell’architettura. 156 International Congress on The Trees of History

1° ELENCO degli ALBERI MONUMENTALI (D.G.R. n. 37 8157 del 30.12.2002) Torino, April 1st - 2 nd, 2004 157

ALBERI MONUMENTALI con procedimento in corso per l’apposizione del vincolo (fase di pubblicazione) 158 International Congress on The Trees of History

ALBERI MONUMENTALI con procedimento avviato (fase di ulteriore accertamento delle caratteristiche)

Consiglio regionale del Piemonte

Legge regionale 3 aprile 1995, n. 50. Tutela e valorizzazione degli alberi monumentali, di alto pregio naturalistico e storico, del Piemonte. (B.U. 12 aprile 1995, n. 15)

Art. 1. (Finalita’) 1. La Regione Piemonte individua, in attuazione dell’articolo 5 dello Statuto gli alberi, i filari e le alberate monumentali, di interesse paesaggistico-ambientale e storico-culturale presenti sul territorio regionale e ne promuove la tutela e la valorizzazione. 2. Sono inclusi nella competenza della presente legge anche gli alberi, i filari e le alberate gia’ sottoposti a vincolo di tutela da parte della legislazione regionale e nazionale.

Art. 2. (Definizione) 1. Ai fini della presente legge sono considerati alberi, filari ed alberate monumentali di interesse storico-culturale e ambientale-paesaggistico: a) alberi isolati o facenti parte di formazioni boschive naturali o artificiali che per eta’ o dimensioni possono essere considerati come rari esempi di maestosita’ o longevita’; b) alberi che hanno un preciso riferimento ad eventi o memorie rilevanti dal punto di vista storico o culturale; c) filari ed alberate di particolare pregio paesaggistico, monumentale, storico-culturale, ivi comprese quelle inserite nei centri urbani.

Art. 3. (Censimento) 1.La Giunta Regionale, entro sessanta giorni dalla approvazione della presente legge adotta, con propria deliberazione, la metodologia di rilevazione ed una scheda di identificazione allo scopo di predisporre il censimento degli alberi, dei filari e delle alberate monumentali di interesse paesaggistico-ambientale e storico-culturale. 2. Il censimento deve raccogliere in particolare dati ed informazioni relativi a: a) localizzazione; b) proprieta’; c) caratteristiche floristiche e dendrometriche; d) descrizione delle caratteristiche monumentali o storico-culturali o paesaggistico-ambientali che motivano l’inclusione nel censimento; e) condizioni fitosanitarie, vulnerabilita’, rischi ed eventuali interventi necessari per garantire la conservazione. Torino, April 1st - 2 nd, 2004 159

3. Singoli cittadini, Organi ed Enti pubblici o Associazioni possono segnalare alla Giunta Regionale l’esistenza di alberi, filari o alberate aventi le caratteristiche descritte all’articolo 2. 4. La Giunta Regionale sentito il parere obbligatorio e vincolante della Commissione Tecnica di cui all’articolo 4, predispone ed aggiorna periodicamente l’Elenco degli alberi, dei filari e delle alberate monumentali, di interesse paesaggistico-ambientale e storico-culturale della Regione Piemonte, che viene pubblicato integralmente sul Bollettino Ufficiale della Regione Piemonte. 5. Gli alberi, i filari e le alberate inseriti in tale elenco devono essere individuati negli strumenti urbanistici comunali ai sensi dell’articolo 24 della legge regionale 5 dicembre 1977, n. 56. 6. L’inclusione nell’elenco di cui al comma 4 comporta, ai sensi dell’articolo 9 della L.R. 56/ 1977 l’istituzione del vincolo di cui alla legge 29 giugno 1939, n. 1497 sulla protezione delle bellezze naturali e panoramiche.

Art. 4. (Commissione tecnica per la tutela e la valorizzazione degli alberi, filari ed alberate monumentali)

1. È istituita la Commissione Tecnica per la tutela e la valorizzazione degli alberi, filari ed alberate monumentali. 2. La Commissione e’ composta da: a) Assessore ai Beni ambientali e paesaggistici o suo delegato con funzioni di Presidente; b) Assessore ai Beni culturali o suo delegato; c) rappresentante dell’Istituto per le piante da legno e l’ambiente (I.P.L.A.); d) rappresentante della Soprintendenza per i beni ambientali ed architettonici del Piemonte; e) rappresentante del Corpo Forestale dello Stato; f) rappresentante della Facolta’ di Scienze Forestali dell’Universita’ di Torino. Svolge le funzione di Segretario della Commissione un funzionario del Settore Beni ambientali e paesaggistici della Regione nominato con decreto del Presidente della Giunta Regionale. La Commissione e’ validamente costituita quando sia stata nominata la maggioranza dei suoi membri. 3. La Commissione formula parere obbligatorio e vincolante alla Giunta Regionale in merito alla inclusione nell’elenco di cui all’articolo 3 degli alberi, filari e alberate di cui e’ stata predisposta la scheda di identificazione. 4.La Commissione esprime inoltre parere in ordine ai finanziamenti per gli interventi di cura ordinaria e straordinaria, nonche’ di valorizzazione di cui agli articoli 5 e 6. 5. La Commissione esprime altresi’ parere obbligatorio e vincolante sull’eventuale abbattimento degli alberi, filari e alberate inclusi nell’Elenco di cui all’articolo 3. 6.La Commissione si riunisce su convocazione del Presidente, su richiesta dell’Assessore dei Beni ambientali e paesaggistici o dell’Assessore ai Beni culturali, o su richiesta di almeno un terzo dei suoi componenti. 7.Le riunioni della Commissione sono valide con la partecipazione della maggioranza assoluta dei componenti. 8.La Commissione dura in carica cinque anni e scade con lo scioglimento del Consiglio Regionale. Essa svolge la sua attivita’ finche’ non siano insediati i nuovi componenti. 9.Ai membri della Commissione spettano per ogni riunione i gettoni di presenza e le eventuali indennita’ di rimborso spese previste dalla vigenti leggi regionali in materia.

Art. 5. (Interventi di cura ordinaria e straordinaria)

1.La Regione Piemonte eroga contributi per la cura ordinaria e straordinaria degli alberi, dei filari e delle alberate inclusi nell’elenco di cui all’articolo 3. 2.Gli interventi di cui al comma 1 sono eseguiti dai proprietari o dagli aventi diritto, su richiesta propria o della Regione Piemonte, a seguito di parere obbligatorio e vincolante di un esperto nominato dalla Giunta Regionale. 160 International Congress on The Trees of History

Art. 6. (Interventi di valorizzazione)

1. La Giunta Regionale, anche su istanza dei proprietari o degli aventi diritto, puo’ promuovere iniziative di valorizzazione degli alberi, filari ed alberate inclusi nell’elenco di cui all’articolo 3, al fine di divulgarne la conoscenza ed il significato della tutela, nonche’ per migliorare il contesto territoriale ed ambientale circostante.

Art. 7. (Norme finanziarie)

1. Agli oneri necessari per il conseguimento dei fini di cui alla presente legge, valutati in lire 20 milioni per l’anno finanziario 1995, si provvede mediante una riduzione di pari ammontare, in termini di competenza e di cassa, del capitolo 15190 dello stato di previsione della spesa per l’anno finanziario 1995 e mediante l’istituzione, nello stato di previsione medesimo, di apposito capitolo con la denominazione “Spese per la tutela e la valorizzazione degli alberi, dei filari e delle alberate di interesse monumentale” e con lo stanziamento di competenza e di cassa di lire 20 milioni. 2. Il Presidente della Giunta Regionale e’ autorizzato ad apportare, con proprio decreto, le occorrenti variazioni di bilancio. Torino, April 1st - 2 nd, 2004 161

IL CENSIMENTO E LA GESTIONE DEGLI ALBERI MONUMENTALI: L’ESPERIENZA DELLA REGIONE LOMBARDIA P. Lenna, G. Galasso Regione Lombardia - Direzione Generale Qualità dell’Ambiente - Struttura Azioni per la Gestione delle Aree Protette e la Difesa della Biodiversità - Milano (MI) Italia

Premessa La Lombardia, regione densamente popolata e ad alto indice di sviluppo, tra le prime in Europa per tasso di occupazione e reddito, conserva ancora gioielli naturali di altissimo valore nonché scorci di paesaggio legati al passato e alle tradizioni dell’uomo. Un patrimonio che, vent’anni fa, la Regione Lombardia ha deciso di salvaguardare attraverso l’istituzione dei Parchi regionali, delle Riserve e Monumenti naturali e dei Parchi locali di interesse sovracomunale. Un sistema di pianificazione territoriale che ha consentito di gestire con forme differenziate di tutela più del 20% del territorio e che, oggi, costituisce la solida base della rete ecologica lombarda, inserita nella più vasta strategia di conservazione della natura in Europa. La Regione Lombardia è stata la prima in Italia a istituire un Assessorato all’Ecologia, nell’ormai lontano 1970, e anche con la sua attività legislativa in materia di parchi e riserve ha svolto un ruolo pionieristico. Già nel 1973, con la legge regionale n. 58 ha posto sotto tutela biotopi e geotopi di interesse naturalistico e scientifico e ha dato l’avvio alla istituzione dei primi parchi (Ticino, 1974; Nord Milano, 1975; Groane, 1976 e Colli di Bergamo (1977). Dieci anni più tardi è stata approvata la legge regionale 86/1983 “Piano regionale delle aree regionali protette. Norme per l’istituzione e la gestione delle riserve, dei parchi e dei monumenti naturali nonché delle aree di particolare rilevanza naturale e ambientale”, ben 8 anni in anticipo sulla normativa nazionale (l. 394/1991). Da alcuni anni il sistema lombardo delle aree protette è ancora più articolato. La Regione Lombardia ha infatti avviato nuove forme di tutela del territorio in base alle ultime direttive comunitarie in materia di habitat e specie. Al 31 dicembre 2003 il sistema risultava così articolato: · 1 Parco nazionale; · 21 Parchi regionali; · 4 Parchi naturali; · 60 Riserve naturali; · 27 Monumenti naturali; · 45 Parchi locali di interesse sovracomunale; · 176 Siti di importanza comunitaria (di cui 85 già approvati dalla Comunità Europea); · 8 Zone di Protezione Speciale. Le azioni di tutela riguardano però non solo le aree protette ma l’intero territorio regionale, grazie al coinvolgimento di tutti i soggetti istituzionalmente preposti (Comuni, Comunità montane e Province) e alla sempre maggior sensibilità e disponibilità del mondo accademico, delle associazioni e dei privati. Un esempio significativo di questa collaborazione è proprio il censimento degli alberi monumentali. La Lombardia è forse la Regione italiana che ospita la più ampia varietà di specie arboree, grazie alla diversità di ambienti che ne caratterizzano il territorio, dai grandi bacini lacustri insubrici alle montagne alpine e appenniniche, fino alle campagne planiziali con gli esemplari sopravvissuti alla meccanizzazione agricola. L’inventario e la tutela delle piante più meritevoli assume, inoltre, un ulteriore significato più prettamente scientifico, rendendo possibile lo studio di questi alberi eccezionali nel tentativo di scoprire se devono la loro lunga vita, oltre al caso che li ha preservati, anche al loro patrimonio genetico, che può averli resi più idonei di altri a sopportare e superare le difficoltà, le malattie e i danni che gli anni portano con sé. La Regione Lombardia, attraverso la collaborazione delle Province, ha avviato sin dal 1989 il censimento degli alberi monumentali. Da allora è iniziato un importante lavoro di stimolo e di coordinamento e, nel corso di diverse riunioni, è stato predisposto un protocollo per attribuire agli esemplari arborei la qualifica di “monumentale”, raccogliere i numerosi dati e archiviarli. Il percorso di lavoro via via condiviso è stato il seguente: 1. rilevamento 1a fase: raccolta di segnalazioni da parte di volontari, 2. rilevamento 2a fase: verifica da parte di tecnici, 3. predisposizione di uno schedario provinciale, 4. predisposizione di un data-base possibilmente collegato a un gis, 5. pubblicazione di uno stralcio dei risultati, 6. tutela, all’interno del Piano territoriale di coordinamento provinciale (PTCP), degli alberi monumentali individuati 162 International Congress on The Trees of History

Una fase successiva potrebbe prevedere lo stanziamento di fondi per la manutenzione straordinaria degli alberi monumentali stessi: potature, interventi di dendrochirurgia ecc. Numerose Province hanno iniziato celermente il lavoro di censimento: alcune lo hanno già concluso e hanno pubblicato i loro dati; altre hanno già inserito gli alberi monumentali individuati all’interno del loro PTCP; altre ancora hanno appena avviato l’attività. La prima Provincia a intraprendere la fase esecutiva dell’indagine è stata Pavia. Nel contempo è stato organizzato un seminario il 18 novembre 1997 a Milano e sono state realizzate due pubblicazioni, una del 1999 relativa alla sola Provincia di Sondrio e una del 2000 relativa alle Province di Brescia, Milano, Pavia e Sondrio: AAVV., 1999 - Alberi monumentali della Provincia di Sondrio. 1o censimento. Provincia di Sondrio, Azienda Regionale delle Foreste, Sondrio. AAVV., 2000 - Gli alberi monumentali della Lombardia. Regione Lombardia, Il Verde Editoriale, Milano.

Scheda di rilevamento e informazioni raccolte Per l’esecuzione del censimento è stata predisposta una scheda informatizzata che permette di rendere omogenei e confrontabili i dati raccolti nei diversi contesti territoriali e amministrativi; gli stessi dati potranno quindi essere elaborati e resi su cartografia GIS. La scheda, realizzata in Microsoft-Acceess e aggiornata nel corso del 2003, permette di descrivere ciascun albero, filare o gruppo di alberi attraverso la raccolta di informazioni su: localizzazione, tassonomia, aspetti di monumentalità, caratteristiche morfologiche e biologiche, condizioni vegetative e sanitarie. Tale scheda è stata redatta per essere utilizzata sia nella fase di prima indagine territoriale, durante la quale il personale incaricato si limiterà a compilare solo le voci per le quali è in grado di fornire un’informazione esauriente, sia nella successiva fase di verifica specialistica. La scheda è articolata nelle seguenti sezioni tematiche.

Numero della scheda, data del rilievo, estremi del rilevatore Localizzazione geografica Riporta l’ambito territoriale del rilievo, ovvero la Provincia, il Comune, la località e, se disponibile, l’indirizzo; ove necessario viene descritto brevemente l’ambito in oggetto e il percorso necessario per raggiungere l’esemplare, facendo riferimento a elementi di facile individuazione sul tracciato (cartelli indicatori, case isolate, bar ecc.). Laddove reperibili sono riportati anche i dati catastali (numero di foglio e di mappale), soprattutto se ci si trova in ambito privato. Sono infine indicati i dati relativi all’esposizione, alla pendenza media e al tipo di ambiente (urbano o extraurbano).

Tassonomia e carattere del rilevamento Oltre al nome scientifico è indicato se si tratta di un esemplare singolo, di un filare o di un gruppo di alberi. Nel caso di raggruppamento viene specificato il numero degli individui.

Aspetti di monumentalità Un esemplare arboreo può essere definito monumentale in base a diversi criteri: · monumentalità architettonica: esemplari legati a edifici di elevato valore storico-culturale; · monumentalità paesaggistica: piante collocate in un contesto territoriale di elevato valore estetico o la cui presenza caratterizza un certo luogo; · monumentalità storico-culturale: l’importanza della pianta è legata a particolari eventi della storia locale, tradizioni, leggende ecc.; · monumentalità legata alla forma; · monumentalità legata alla rarità botanica: si riferisce a specie non tipiche dell’ambiente in cui crescono (es. piante ben sviluppate al di fuori dalla loro tipica fascia bioclimatica) e poco rappresentate numericamente; · monumentalità dimensionale: legata alla circonferenza. L’aspetto di monumentalità dimensionale viene selezionato direttamente dal programma, che tiene conto dei valori di circonferenza inseriti nella descrizione fisionomica. Inizialmente i limiti dimensionali erano correlati alla zona bioclimatica di Gams; tuttavia ci si è presto svincolati da questa e attualmente sono stabiliti i seguenti limiti regionali, anche se ogni Provincia può discostarsene per meglio adattarli alla sua realtà locale: Torino, April 1st - 2 nd, 2004 163

Descrizione fisionomica In questo parte della scheda sono descritte le caratteristiche morfologiche e biologiche, quali l’altezza, la circonferenza del fusto, il diametro della chioma e il portamento: · tronco: è indicato se è monocormico o policormico; · portamento: arboreo, arbustivo, prostrato o rampicante; · n° fusti: è indicato il numero dei fusti di un individuo policormico; · circonferenza: è misurata in centimetri a petto d’uomo (a 130 cm dal suolo); in caso di albero policormico si riporta la somma delle circonferenze di tutti i fusti; · altezza: è espressa in metri, valutata o misurata; se l’albero è policormico si riporta l’altezza del fusto più elevato; · età: età stimata o misurata, indicata mediante un intervallo di anni: <100, 100-200, >200; · diametro della chioma: è indicato il diametro medio della chioma, espresso in metri; · forma della chioma: è indicato se espansa, pendula, colonnare o piramidale; · carattere della chioma: è indicato se obbligata o naturaliforme; questo dato fornisce una prima indicazione in merito ad eventuali interventi quali ad esempio potature; · altezza del 1° palco: è indicata l’altezza da terra, espressa in metri.

Quadro vegetativo Il quadro vegetativo fornisce una prima valutazione generale dello stato di salute dell’esemplare arboreo: · vigore vegetativo: buono, medio o scarso; · seccume: assente, incipiente o diffuso; · microfillia: assente, significativa o evidente; questo carattere si riferisce a foglie dalle dimensioni più ridotte rispetto al normale sviluppo, sintomo da imputare all’azione di diversi agenti biotici e abiotici quali stress idrico, carenze nutrizionali, attacchi fungini, inquinamento ecc.; · riscoppi: assenti o presenti; trattasi di rami provenienti da gemme dormienti, che si sviluppano a seguito dell’azione di diversi fattori quali stress idrici, funghi, virus ecc.

Quadro strutturale Questa sezione è finalizzata a fornire indicazioni generali circa la stabilità meccanica e considera le seguenti regioni anatomiche: · aspetto dell’apparato radicale: buono, medio o scarso; · aspetto del colletto: buono, medio o scarso; · aspetto del fusto: buono, medio o scarso; · aspetto della chioma: buono, medio o scarso; · aspetto delle branche: buono, medio o scarso; · note: breve descrizione dei sintomi rilevati.

Quadro fitosanitario Viene indicata l’eventuale presenza di infestazioni, infezioni o carpofori, specificando l’agente patogeno e la collocazione anatomica: · infestazioni: riferite a parassiti quali insetti e acari; · infezioni: riferite a malattie fungine, virali e batteriche; · carpofori: presenza di corpi fruttiferi fungini appartenenti a specie dei generi Armillaria, Ganoderma, Phellinus, Phomes, Rosellinia ecc. 164 International Congress on The Trees of History

Interventi effettuati Si tratta di informazioni aggiuntive relative alla storia dell’esemplare monumentale, segnalate laddove siano evidenti o confermate da informazioni attendibili; se possibile sono specificate la tipologia e la localizzazione: · potatura: di rimonda, di diradamento, di contenimento ecc.; effettuata su branche primarie ecc. · consolidamenti: effettuati con l’utilizzo di cavi in acciaio passanti o altro; localizzati a livello di branche primarie ecc.; · ancoraggi: cavi in acciaio, funi ecc.; · altro: altri dati, tra i quali concimazione, trattamenti antiparassitari ecc.; · note: sono indicate le eventuali operazioni future consigliate.

Informazioni sul terreno È indicato il tipo di copertura e il grado di costipamento del suolo ai piedi della pianta: · terreno: nudo, inerbito, cespugliato, pavimentato o impermeabilizzato; · caratteristiche: debolmente compattato, mediamente compattato, fortemente compattato; · altro.

Quadro minacce Viene segnalato quale elemento di disturbo può minacciarne l’integrità: · errata gestione: presenza di grossi tagli di potatura, irrigazioni eccessive o inesistenti, carenze nutrizionali ecc.; · urbanizzazione: presenza di cantieri di lavoro in corso che possono pregiudicare la pianta (scavi per servizi, marciapiedi, parcheggio d’auto in prossimità dell’esemplare) ecc.; · instabilità del terreno: presenza di cedimenti del versante o aree a franosità diffusa che possono mettere in pericolo la stabilità dell’esemplare; · fuoco: esemplari ubicati in zone soggette a incendio; · rischio di taglio: esemplari ubicati in aree di sviluppo urbanistico che rischiano l’abbattimento; · altro.

Quadro vincoli Sono segnalati i vincoli esistenti in base alla normativa vigente: vincolo idrogeologico, vincolo ex l. 490/1999.

Quadro tutela È indicato se l’albero censito è stato inserito ufficialmente: a) nell’elenco degli alberi monumentali, riportando gli estremi del relativo atto amministrativo provinciale, b) nel Piano Territoriale di Coordinamento Provinciale e/o se è c) Monumento naturale ai sensi della l.r. 86/1983.

Attribuzione di punteggi agli alberi monumentali e ripartizione in classi di merito Uno degli scopi del censimento degli alberi monumentali è quello di poterli tutelare attivamente, anche mediante lo stanziamento di fondi per la loro manutenzione straordinaria. Per fare questo è però necessario attribuire a ogni albero un punteggio che permetta di stilare, a livello provinciale, delle graduatorie di priorità. La Provincia di Sondrio è stata la prima a proporre un sistema che giunge a distribuire gli alberi in tre categorie: I° élite, I° e II°. Alla fine del 2003 la Provincia di Como, nel corso della revisione della scheda di rilevamento, ha proposto un nuovo sistema che è stato condiviso da tutte le Province; esso, lavorando attraverso l’applicazione di tre filtri successivi, ripartisce gli alberi in tre classi di merito (classe 1, classe 2, classe 3). Il primo filtro tiene conto dei criteri di monumentalità. A ogni albero viene attribuito automaticamente un punteggio in base ai parametri “Aspetti di monumentalità” inseriti nella scheda. La monumentalità dimensionale contribuisce molto meno degli altri aspetti nella formazione del punteggio; la misura della circonferenza sarà determinante durante l’applicazione del secondo filtro. Gli esemplari censiti vengono così ripartiti in tre classi provvisorie. Le classi 2 e 3 provvisorie passano al secondo filtro, mentre quelle della classe provvisoria 1 saltano direttamente al terzo e ultimo filtro. Il secondo filtro agisce sui parametri dimensionali, cioè sulla circonferenza, e, come detto, agisce soltanto sulle classi provvisorie 2 e 3. Per ogni esemplare la selezione si base sul confronto tra la sua circonferenza, il limite minimo di soglia per quella specie (vedi Torino, April 1st - 2 nd, 2004 165

“Aspetti di monumentalità”) e il valore medio per quella specie (calcolato automaticamente e solo per i valori rilevati oltre la soglia minima). Il terzo filtro si basa sul punteggio attribuito automaticamente ai singoli esemplari in base al “Quadro vegetativo”, al “Quadro strutturale” e al “Quadro fitosanitario” della scheda di rilevamento. Come detto, il sistema tiene conto della media delle circonferenze. Di conseguenza ogni volta che vengono caricate nuove schede i valori e i relativi punteggi possono variare. Pertanto il procedimento di attribuzione dei punteggi e la successiva ripartizione in classi di merito, entrambi automatizzati, dovranno avvenire alla fine del censimento. Lo schema seguente illustra il procedimento logico adottato dai tre filtri successivi. 166 International Congress on The Trees of History

Svolgimento del Censimento e risultati Come detto, la Regione Lombardia a partire dal 1989 ha promosso e contribuito, con proprie risorse tecniche e finanziarie, al censimento di tali “monumenti vegetali”, partendo dalle Province di Pavia, Milano, Brescia e Sondrio, caratterizzate da condizioni socio-ambientali diverse tra loro e sufficientemente rappresentative dell’eterogeneità territoriale regionale. Ai censimenti hanno collaborato attivamente i Comuni, il Corpo forestale dello stato, l’Ente regionale per i servizi agricoli e forestali (ERSAF), le scuole, le associazioni ambientaliste e i privati, sia in quanto proprietari di alberi notevoli sia in qualità di studiosi e cultori della materia. Le Guardie ecologiche volontarie (GEV), in particolare, grazie alla loro radicata conoscenza del territorio, hanno rappresentato un riferimento insostituibile nella rilevazione di un grande numero di esemplari altrimenti sconosciuti.

Provincia di Pavia Pavia è stata, come detto, la prima Provincia lombarda a iniziare nel 1989 il censimento degli alberi monumentali, affidando l’incarico a professionisti esterni all’Amministrazione. Trattandosi della prima esperienza attuata a livello regionale, lo studio è stato seguito in tutte le sue fasi da un gruppo di lavoro interdisciplinare formato da studiosi e professionisti di diversa estrazione (botanici, agronomi, forestali, architetti, paesaggisti e storici). Tale gruppo di lavoro, attraverso l’esame delle esperienze già maturate in altre realtà italiane ed estere, ha elaborato delle linee guida sia per l’organizzazione della fase dei rilievi di campagna sia per la successiva disamina dei dati raccolti. Dall’indagine territoriale sono state escluse tutte le aree già tutelate comprese nel Parco del Ticino e nelle Riserve naturali. La fase di prima raccolta delle segnalazioni e di verifica di quelle trasmesse da parte di alcuni Comuni è stata portata a termine dalle Guardie ecologiche volontarie, che sono state coinvolte in forza della loro passione per la natura e la specifica conoscenza dei luoghi; un breve corso mirato ha consentito alle GEV di acquisire le informazioni di base indispensabili alla conduzione dell’indagine sul territorio. Le segnalazioni, poi, sono state vagliate da tecnici esperti (agronomi, forestali e botanici) sulla base delle informazioni riportate sulle schede di campagna e della consultazione del materiale fotografico allegato; i rilievi che hanno superato la prima fase di selezione a tavolino sono stati sottoposti a una successiva verifica sul posto. In seguito, i risultati della verifica sono stati esaminati mediante l’applicazione di un criterio di analisi elaborato ad hoc dal gruppo di lavoro. Trattandosi dell’esperienza guida per la Lombardia, i criteri di riferimento per individuare le piante di interesse monumentale, derivati dalla letteratura e da esperienze condotte fuori regione hanno determinato una selezione piuttosto marcata delle piante già nella fase di prima raccolta delle segnalazioni. Pertanto, per la Provincia di Pavia il numero complessivo dei rilievi risulta, mediamente, inferiore a quello registrato nelle successive esperienze dove sono stati usati, viceversa, nuovi criteri derivati proprio da questo primo censimento. In un secondo momento, terminato nel 2002, il censimento è stato riverificato e integrato coi dati delle aree protette. Il lavoro è stato commissionato a professionisti esterni all’Amministrazione, che si sono avvalsi della collaborazione del Corpo forestale dello stato. Attualmente gli alberi monumentali sono stati inseriti all’interno del PTCP con una norma che ne salvaguarda la conservazione, fatta salva la possibilità di abbattimenti per problemi di stabilità o fitopatologici. Risultati: segnalazioni raccolte nella prima fase 247, segnalazioni sottoposte a verifica 224, alberi monumentali 31 (esemplari singoli: 26; gruppi: 4; filari: 1), generi botanici più rappresentati Quercus (5), Castanea (4), Populuss (4).

Provincia di Milano La Provincia di Milano ha avviato il censimento nel 1992, organizzando un gruppo di lavoro interdisciplinare composto da tecnici interni all’Amministrazione. Anche in questo caso sono state escluse le aree protette. Le GEV non hanno potuto completare la prima fase del censimento a causa di alcuni problemi organizzativi; pertanto la Provincia ha provveduto a conferire a un professionista esterno l’incarico di portare a termine la fase di rilievo di campagna e la verifica delle segnalazioni inviate da parte di alcuni Comuni. Sia durante l’esecuzione dei rilievi sia nella successiva analisi delle informazioni sono stati sostanzialmente utilizzati i criteri messi a punto nel corso del precedente studio della Provincia di Pavia; ciò ha consentito di sottoporre la metodologia a un valido test di verifica che ha permesso di affinare l’approccio tecnico- Torino, April 1st - 2 nd, 2004 167 metodologico, adattandolo alla realtà provinciale del milanese. Una volta elaborato l’elenco degli alberi monumentali, la Provincia ha avviato, nel 1997, una fase di sperimentazione invitando i Comuni a richiedere, dietro presentazione di un progetto, l’erogazione di un finanziamento per sottoporre alcuni esemplari a interventi di tutela e manutenzione straordinaria; in totale sono stati impegnati e spesi circa 35.000.000 £ per 17 alberi. Attualmente gli alberi monumentali sono stati inseriti all’interno del PTCP (approvato con delibera di consiglio provinciale 14 ottobre 2003, n. 55, pubblicata sul B.U.R.Lombardia serie inserzioni, n. 45 del 5 novembre 2003) con una norma (art. 65) che ne salvaguarda la conservazione, fatta salva la possibilità di abbattimenti per problemi di stabilità o fitopatologici. Dal punto di vista della cartografia del PTCP, in scala 1:25.000, la localizzazione è di tipo ideogrammatico e quindi indicativa. In ogni caso, il Comune può chiedere alla Provincia la localizzazione puntuale, disponibile in scala 1: 10.000. Risultati del censimento: segnalazioni raccolte nella prima fase 1.103, segnalazioni sottoposte a verifica 223, alberi monumentali 223 (esemplari singoli: 136; gruppi: 65; filari: 22), generi botanici più rappresentati Quercus (352), Celtis (164), Platanus (126). Tra il completamento del censimento e l’approvazione del PTCP, l’elenco degli alberi monumentali è stato aggiornato, giungendo a 233 segnalazioni corrispondenti a 1399 esemplari: esemplari singoli 146 corrispondenti a 146 esemplari, filari monospecifici 22 corrispondenti a 788 esemplari, gruppi monospecifici 60 corrispondenti a 438 esemplari, gruppi plurispecifici 5 corrispondenti a 27 esemplari.

Provincia di Brescia La terza Provincia che ha intrapreso il censimento degli alberi monumentali è stata Brescia che, nel 1994, ha incaricato professionisti esterni all’Amministrazione. Anche in questo caso sono state escluse le aree protette. Data la complessità territoriale che caratterizza il bresciano è stato fondamentale il coinvolgimento delle GEV, la cui motivazione è stata alimentata anche grazie alla organizzazione di un breve corso formativo, utile sia per delineare un quadro generale degli obiettivi sia per fornire le adeguate precisazioni operative per una corretta conduzione delle indagini di campagna. Inoltre, ciascun gruppo di Guardie ecologiche volontarie è stato puntualmente seguito da un responsabile che ha operato in stretto contatto coi coordinatori provinciali del progetto e coi professionisti incaricati. Nell’ambito dell’organizzazione del lavoro si è tenuto conto di quanto emerso dalle due precedenti esperienze, sia per lo svolgimento dell’indagine di campagna sia per la successiva fase di verifica e analisi delle informazioni raccolte. Con la Provincia di Brescia, tra l’altro, il censimento si è esteso ad altre unità di paesaggio non interessate dagli studi precedenti (aree lacustri, prealpine e alpine), la qual cosa ha reso possibile l’integrazione degli elenchi degli alberi censiti con le specie tipiche della flora mediterranea e delle quote altimetriche più elevate. Risultati: segnalazioni raccolte nella prima fase 608, segnalazioni sottoposte a verifica 339, alberi monumentali 167 (esemplari singoli: 102; gruppi: 52; filari: 13), generi botanici più rappresentati Fagus (177), Quercus (135), Taxodium (103).

Provincia di Sondrio La Provincia di Sondrio ha dato il via al censimento nel 1997, avvalendosi della collaborazione dell’Azienda regionale delle foreste (ARF, oggi ERSAF). L’indagine ha interessato, a differenza delle altre province, tutto il territorio coinvolgendo anche le aree protette. Sull’esempio della linea operativa seguita nelle altre province lombarde, il censimento si è articolato in una fase iniziale di campagna e nella successiva verifica delle segnalazioni. Innanzitutto le schede di segnalazione sono state distribuite a tutti i Comuni e agli operatori di vari Enti e associazioni che si occupano a vario titolo di ambiente (es. GEV, Enti gestori dei Parchi, CAI, Legambiente e WWF), opportunamente informati e addestrati. Altre schede sono state distribuite anche a privati cittadini tramite comunicati stampa diffusi per mezzo di giornali, radio e televisione. Le segnalazioni acquisite durante la fase di rilievo sono state sottoposte a un primo riscontro comparativo che ha condotto a scartare tutti gli esemplari che non raggiungevano una determinata soglia minima, calcolata applicando i risultati ottenuti nelle altre province e modulata attraverso valutazioni specifiche legate al particolare ambito 168 International Congress on The Trees of History territoriale. La verifica specialistica e la successiva analisi statistica dei risultati sono state condotte da personale tecnico specializzato. La particolare configurazione orografica della provincia ha permesso di arricchire ulteriormente le informazioni disponibili a livello regionale, integrando l’elenco delle specie censite con l’introduzione di quelle prevalentemente alpine. Il numero finale degli alberi monumentali non è particolarmente elevato, sia a causa dello sfruttamento forestale dei boschi ancora in atto in questa provincia sia per la scarsa presenza di dimore storiche che, in altre province, hanno garantito la conservazione di alcuni esemplari nel corso degli anni divenendo, pertanto, fonte di numerose segnalazioni. Probabilmente gli alberi monumentali individuati verranno inseriti all’interno del PTCP con una norma che ne salvaguardi la conservazione, fatta salva la possibilità di abbattimenti per problemi di stabilità o fitopatologici. Risultati: segnalazioni raccolte nella prima fase 212, segnalazioni sottoposte a verifica 168, alberi monumentali 133 (esemplari singoli: 107; gruppi: 23; filari: 3), generi botanici più rappresentati Castanea (24), Fagus (18), Larix (11).

Provincia di Bergamo Il lavoro, svolto su tutto il territorio provinciale comprese le aree protette, è iniziato nel 1998 ed è ormai in conclusione. Nella fase di raccolta dei dati ci si è avvalsi della preziosa collaborazione di GEV, aree protette, Comuni, Corpo Forestale dello Stato e varie associazioni naturalistiche e ambientali; la loro attività ha prodotto circa 1.150 segnalazioni. Per la successiva verifica tecnica ci si è affidati a tecnici esterni alla Amministrazione, coordinati dall’Orto Botanico di Bergamo. Le segnalazioni ritenute monumentali sono circa 400 e attualmente si sta valutando quali inserire all’interno del PTCP con una norma che ne salvaguardi la conservazione, fatta salva la possibilità di abbattimenti per problemi di stabilità o fitopatologici.

Provincia di Lodi Il lavoro, svolto su tutto il territorio provinciale comprese le aree protette, è iniziato nel 1999 ed è ormai entrato nella fase finale. L’incarico è stato affidato a un tecnico esterno alla Amministrazione. Nella fase di raccolta dei dati ci si è avvalsi della preziosa collaborazione di GEV, aree protette e Comuni; la loro attività ha prodotto circa 700 segnalazioni. Attualmente sono stai selezionati circa 100 esemplari da sottoporre alla verifica tecnica.

Provincia di Como Il lavoro, svolto su tutto il territorio provinciale, è iniziato nel 2001 ed è ormai entrato nella seconda e ultima fase. La ricerca, a partire dall’esperienza maturata nelle altre Province, è stata caratterizzata da una fase iniziale di predisposizione delle azioni da intraprendere; a tal fine è stato nominato un apposito “Tavolo tecnico-scientifico”. È stata anche verificata l’esistenza di precedenti e analoghi lavori, attività che ha consentito il recupero dei dati di censimenti compiuti negli anni 90 da parte del WWF e del Corpo Forestale dello Stato. Nella fase di raccolta dei dati si è cercato di coinvolgere, oltre alle GEV, le scuole, i Comuni e le Associazioni, anche i numerosi edifici e ville storiche con parco e/giardino vincolati ai sensi della normativa vigente. Questo lavoro ha prodotto circa 500 segnalazioni da sottoporre alla successiva verifica tecnica. Nel corso del lavoro si è anche compiuta una rivisitazione della scheda di rilevamento e del relativo data-base di archiviazione e di calcolo dei punteggi.

Provincia di Lecco Il lavoro, svolto su tutto il territorio provinciale, è iniziato nel corso del 2002 ed è ormai entrato nella seconda e ultima fase. L’incarico è stato affidato al WWF. Nella fase di raccolta dei dati ci si è avvalsi dei volontari del WWF, mentre con le GEV si sta procedendo alla georeferenziazione degli esemplari sinora segnalati. La prima fase di raccolta dati ha prodotto circa 850-900 segnalazioni, che saranno sottoposte alla verifica tecnica da parte di un esperto forestale del WWF. Sempre con la collaborazione da parte delle GEV si stanno individuando dei “percorsi turistici” alla scoperta degli alberi monumentali della provincia; attualmente si sta lavorando su circa 15 itinerari. Torino, April 1st - 2 nd, 2004 169

Provincia di Cremona Il lavoro di censimento è iniziato nel 2004. Come dato di partenza si è tenuto conto di una pubblicazione sui giardini della provincia; questi sono poco più di 100 e oltre la metà hanno almeno un albero monumentale. Per garantire la completezza del censimento sono state coinvolte non solo le GEV ma anche le aree protette e il Gruppo Floristico Cremonese.

Provincia di Mantova Il lavoro è iniziato nel 2004, affidandosi a professionisti esterni alla Pubblica Amministrazione. Sinora è stata inviata un questionario ai Comuni e alcuni hanno già risposto comunicando dati interessanti. Ci si avvarrà anche della collaborazione delle aree protette e delle associazioni ambientaliste e naturalistiche.

Provincia di Varese Il lavoro è iniziato nel 2004, affidandosi a professionisti esterni alla Pubblica Amministrazione. In ogni caso ci si avvarrà anche della preziosa collaborazione di GEV, Comuni, aree protette e associazioni, che nella altre Province hanno contribuito in modo significativo alla fase iniziale di raccolta dei dati.

Prospettive e sviluppi Nel complesso si può affermare che il censimento degli alberi monumentali in Regione Lombardia ha sinora prodotto ottimi risultati. Per completare e migliorare il lavoro si prevede di promuovere le seguenti azioni: · completare i censimenti ancora in corso o appena iniziati; · estendere i censimenti anche all’interno delle aree protette, inizialmente escluse nelle Province di Brescia e Milano; · aggiornare in continuo i censimenti già conclusi; · prevedere, man mano, l’inserimento degli alberi monumentali all’interno dei PTCP; · prevedere l’inserimento dei dati in Carta Naturalistica della Lombardia; · prevedere finanziamenti per l’esecuzione di perizie e di interventi conservativi (potature, dendrochirurgia ecc.); i fondi potrebbero essere liquidati alle Province in proporzione agli alberi censiti; le Province, in seguito, dovrebbero predisporre un bando oppure convenzionarsi con una ditta che provvederà a verificare tutti i casi segnalati intervenendo ove il caso; · prevedere una serie di pubblicazioni divulgative provinciali e una pubblicazione regionale; · prevedere una norma di legge che tuteli gli alberi monumentali e preveda l’erogazione di fondi. 170 International Congress on The Trees of History

L’ESPERIENZA GESTIONALE DELLE PUBBLICHE AMMINISTRAZIONI NELL’AMBITO DELLA TUTELA E VALORIZZAZIONE DEGLI ALBERI MONUMENTALI: IL CASO DELLA REGIONE VENETO E. Piutti, G. Bullo, A. Vieceli Azienda Regionale Veneto Agricoltura, Agripolis – Legnaro (PD)

1. Premessa Il tema degli alberi monumentali è di estrema attualità oltre che particolarmente affascinante e di grande rilievo per la storia dell’intero territorio nazionale e del paesaggio che lo definisce. Infatti, tutela e conservazione di questi “beni vegetali” nasce da motivazioni sia paesaggistiche che ambientali in quanto è riconosciuto che gli alberi, soprattutto quelli di grandi dimensioni, costituiscono la componente più appariscente ed emozionale di qualsiasi luogo e ricoprono un ruolo fondamentale nel determinarne il valore. Gli alberi sono una delle forme di vita più antiche della terra, silenziosi testimoni dell’evoluzione dell’umanità e del passaggio del tempo. La consapevolezza che tali monumenti naturali, caratterizzati da un’elevata ricchezza genetica che li rende tanto forti da superare le siccità più lunghe e resistere ai freddi più intensi, siano giunti fino ai giorni nostri dopo una lunga e complessa evoluzione attraverso i secoli deve far riflettere anche sul loro valore storico-culturale e testimoniale. Gli alberi monumentali, inoltre, costituiscono un peculiare elemento del patrimonio architettonico ed artistico, caratterizzando ed arricchendo gli ambienti esterni di ville, residenze e palazzi storici, dove spesso sono potuti sopravvivere salvaguardati da eventi bellici e dalle modificazioni urbanistiche degli ultimi decenni. Vanno così considerati come beni preziosi da tutelare e conservare nel tempo, costituendo globalmente un patrimonio naturale e paesaggistico con valenza composita meritevole di attenzione. Un albero monumentale ha perciò un grande valore ecologico, estetico e culturale e va valorizzato in quanto componente della memoria collettiva e componente significativa dei paesaggi. Tuttavia, a causa della longevità e senescenza, degli interventi di ripristino e dell’interferenza con le infrastrutture adiacenti, gli alberi monumentali sono piante molto vulnerabili e maggiormente soggette a deperimento. Strettamente connesse alla loro presenza sono le problematiche relative alla manutenzione ed al ripristino ambientale ed architettonico nonché allo spinoso problema delle responsabilità, della gestione e del tipo degli interventi, trovandosi spesso in aree pubbliche e ad elevata valenza sociale.

2. La situazione normativa regionale e nazionale a supporto del censimento e della catalogazione Soprattutto dagli anni ’90 la maggior parte delle Regioni si sta dotando di norme per la tutela, la valorizzazione e la conservazione del patrimonio vegetale di alto pregio e, più specificatamente, degli alberi monumentali. Molti sono i lavori disponibili di censimento e schedatura delle piante monumentali, avviati dalle singole amministrazioni ed associazioni ambientaliste e culturali. La metodologia seguita è quella già utilizzata per il censimento del verde urbano (impiego di un sistema informativo geografico e di schede di rilevamento informatizzate per la raccolta delle caratteristiche morfologiche, fitosanitarie e di stabilità, strutturazione di un database per la programmazione e la gestione degli interventi e costi di manutenzione, ecc.). Numerosi ormai sono gli esempi sia a livello regionale italiano che internazionale di elenchi e pubblicazioni sugli alberi monumentali in ampi ambiti territoriali o più specificatamente di quelli in ville, parchi e giardini.

3. L’esperienza gestionale delle pubbliche amministrazioni: la Regione Veneto 3.1 Quadro storico Nel Veneto il primo organismo istituzionale ad occuparsi di alberi monumentali è stato il Corpo Forestale dello Stato che nel 1982 ha effettuato un censimento che ha interessato gli alberi che come singoli soggetti arborei hanno una propria individualità per essere eccezionalmente vecchi, per essere stati protagonisti di episodi storici o per essere legati alla vita di grandi uomini o di Santi. L’iniziativa, lanciata al livello nazionale nell’estate del 1982 e condotta dal personale del Corpo Forestale dello Stato, ha censito, in Veneto, 57 alberi. La Regione Veneto, nell’ambito dei lavori di redazione del Piano Regionale di Coordinamento, ha avviato, nel 1987, un censimento degli alberi monumentali della Regione. Tale censimento è stato articolato per provincia e a tal fine è stata elaborata una scheda. I lavori di rilievo, Torino, April 1st - 2 nd, 2004 171 eseguiti dal WWF, hanno dato luogo ad una pubblicazione per ogni singola provincia censita, curata dalla Segreteria regionale per il territorio dal titolo “I grandi alberi della Provincia di .”. Il censimento, sospeso nel 1995, ha consentito la pubblicazione di 5 Province su 7 con i seguenti risultati:

Successivamente alcune amministrazioni provinciali hanno effettuato autonomamente attività di censimento. E’ il caso, ad es., della Provincia di Padova che ha eseguito un censimento e una catalogazione degli alberi monumentali presenti nel suo territorio. I dati sono stati inseriti in un programma di gestione informatico. Per ogni singolo albero censito è stata effettuata l’indagine di stabilità secondo il metodo VTA (Visual Tree Assessmant), consentendo così di individuare l’effettivo stato di salute degli alberi e i soggetti a rischio nonché di raccogliere gli elementi per poter mettere in atto le misure di salvaguardia. Il censimento è stato inoltre arricchito da una ricerca storica. Gli alberi censiti dalla Provincia di Padova sono 92. Anche l’Amministrazione Provinciale di Venezia, visto il mancato completamento del censimento regionale ha deciso di procedere in proprio al censimento degli alberi monumentali presenti sul proprio territorio, che è stato completato nel 2002. Il lavoro è stato reso noto con una pubblicazione che descrive 166 degli alberi censiti.

3.2 La Legge Regionale del Veneto n. 20 del 9 agosto 2002 3.2.1 Finalità e definizioni La legge regionale n. 20/2002 “Tutela e valorizzazione degli alberi monumentali”, detta norme per l’individuazione degli alberi monumentali di alto pregio naturalistico e storico, di interesse paesaggistico e culturale presenti nella Regione Veneto. Il testo di legge definisce come alberi monumentali di alto pregio naturalistico e storico e di interesse paesaggistico e culturale: a) gli alberi isolati o facenti parte di formazioni boschive naturali o artificiali che per età o dimensioni possono essere considerati come rari esempi di maestosità o longevità b) gli alberi che hanno un preciso riferimento a eventi o memorie rilevanti dal punto di vista storico o culturale o a tradizioni locali.

3.2.2 Competenze La legge regionale individua l’Azienda Regionale per i settori agricolo, forestale e agro- alimentare, “Veneto Agricoltura”, ente pubblico economico della Regione Veneto, quale soggetto competente per l’istituzione dell’elenco regionale degli alberi monumentali, incaricando la stessa di definire la metodologia di rilevazione e i contenuti informativi della scheda tipo, che dovrà almeno contenere i dati caratteristici di vegetazione e i criteri di tutela. L’inserimento nell’elenco regionale degli alberi monumentali avviene su proposta diretta delle Province, dei Comuni, delle Comunità Montane e degli Enti Parco oppure a seguito di segnalazioni di singoli cittadini o associazioni ai medesimi enti che trasmetteranno a Veneto Agricoltura la segnalazione corredata da un proprio parere. La scheda tipo e l’elenco regionale degli alberi monumentali sono pubblicati nel Bollettino Ufficiale della Regione del Veneto. L’elenco verrà aggiornato periodicamente. Oltre a Veneto Agricoltura, le strutture regionali interessate sono i Servizi Forestali e i Servizi Fitosanitari che assicurano rispettivamente l’assistenza per gli aspetti agroforestali e fitopatologici in merito agli alberi dell’elenco.

3.2.3 Valorizzazione e tutela L’Azienda Regionale Veneto Agricoltura, le Province, i Comuni, le Comunità Montane e gli Enti Parco promuovono iniziative di pubblicizzazione e di valorizzazione degli alberi inclusi nell’elenco al fine di divulgarne la conoscenza, il significato di tutela nonché per migliorare il contesto territoriale e ambientale circostante. Gli alberi inseriti nell’elenco sono segnalati come Albero Monumentale Protetto. I Comuni riportano nel proprio strumento urbanistico generale gli alberi monumentali protetti e le relative aree di pertinenza dettando apposita normativa di tutela. Gli interventi per una corretta manutenzione e conservazione degli alberi monumentali sono autorizzati dal Comune previa acquisizione di un parere tecnico delle 172 International Congress on The Trees of History strutture regionali competenti in materia di servizi forestali e fitosanitari. È vietato a chiunque abbattere, danneggiare o comunque modificare la struttura degli alberi monumentali inseriti nell’elenco regionale, salvo pareri degli enti competenti. L’abbattimento dei alberi inclusi nell’elenco può avvenire per esigenze di pubblica incolumità o per esigenze fitosanitarie e comunque dopo aver accertato l’impossibilità ad adottare soluzioni alternative. I comuni e le strutture regionali competenti in materia di servizi forestali e fitosanitari vigilano sull’applicazione delle disposizioni della presente legge. 3.3 Metodologia utilizzata Sulla base delle finalità e delle disposizioni della legge regionale n. 20/2002, l’Azienda Regionale Veneto Agricoltura ha predisposto un piano triennale di lavoro dal 2003 al 2005. Fase 1 a. Organizzazione, da parte di Veneto Agricoltura, di un incontro a livello regionale al quale sono stati chiamati a partecipare tutti gli Enti e le Associazioni che si sono occupati in passato o che si occupano oggi di alberi monumentali nonché gli Enti Territoriali interessati dalla Legge per la futura applicazione del vincolo; nell’incontro è stato illustrato il contenuto della Legge e presentata la bozza di programma di lavoro che ha dato luogo ad un partecipato e costruttivo dibattito. b. Istituzione di una Commissione Tecnica Consultiva costituita da un rappresentante di Veneto Agricoltura, della Direzione Foreste ed Economia Montana della Regione Veneto, del Servizio Fitosanitario Regionale, del Dipartimento TESAF (TErritorio e Sistemi Agro- Forestali) dell’Università di Padova, del Corpo Forestale dello Stato, della Soprintendenza per i Beni architettonici ed il Paesaggio del Veneto, dell’Associazione Nazionale Comuni d’Italia e del WWF - sezione regionale del Veneto. La Commissione ha il compito di fornire a Veneto Agricoltura il proprio parere tecnico in merito all’inclusione degli alberi nell’elenco regionale. Svolge inoltre un ruolo consultivo in merito alla definizione della scheda tipo per il rilevamento, alla definizione dei criteri di selezione e delle metodologie di rilevazione. c. Determinazione dei requisiti che qualificano una pianta come monumentale e dei criteri di selezione; d. Raccolta e selezione del materiale pubblicato già esistente relativo alle piante già censite e verifica della disponibilità di altri dati rilevati e non ancora pubblicati; e. Definizione di una scheda tipo di censimento in linea con i requisiti richiesti dalla legge regionale (art. 3 comma 2) e conforme sia agli standard di catalogazione e inventario proposti dalla scheda PG – Parchi e Giardini dell’Istituto Centrale per il Catalogo e la Documentazione del Ministero per i Beni e le Attività culturali; f. Progettazione di un software per la gestione delle schede per ogni singola pianta (localizzazione e georeferenziazione, informazioni amministrative, dati morfologici e botanici, dati fitopatologici, dati storico-culturali, criteri di tutela, foto e bibliografia, ecc.) Fase 2 a. Istituzione di un tavolo provinciale per la verifica della selezione eseguita sul materiale pubblicato (fase 1.d.); sono chiamati al tavolo provinciale gli Enti Territoriali, gli altri Enti Pubblici e le Associazioni interessati dall’argomento (Servizi Forestali, Corpo Forestale dello Stato, Servizi fitosanitari, ); b. Sopralluoghi in campo al fine di verificare e implementare le informazioni raccolte nelle schede già esistenti, applicando i criteri e le schede di cui alla fase 1, così da ottenere un primo inventario degli alberi monumentali; c. Individuazione delle piante appartenenti al primo inventario con possibili problemi relativi alla stabilità e allo stato fitosanitario; d. Informatizzazione delle schede relative al primo inventario con georeferenziazione. Fase 3 a. Approfondimento dello stato fitosanitario e verifica della stabilità per le piante per le quali sono stati individuati problemi di sicurezza; b. Cartellinatura delle piante inserite nel primo inventario: “Regione Veneto – Albero monumentale”; c. Formulazione di indicazioni operative sulla pianificazione e sulle modalità di gestione del patrimonio arboreo censito per i Comuni interessati (o gli Enti Gestori nel caso di Parchi o Riserve); d. Divulgazione: predisposizione di un link a tema su sito web dell’Azienda Regionale Veneto Agricoltura, produzione di un CD rom e di un depliant illustrativo del progetto. Torino, April 1st - 2 nd, 2004 173

I principali aspetti da evidenziare nelle fasi di lavoro sono i seguenti: - la costituzione della Commissione tecnica consultiva che consente di poter disporre del contributo e della competenza di esperti afferenti a varie discipline; - la predisposizione di due prospetti (Tabella 1 e Tabella 2) utili ai fini della classificazione di una pianta come “monumentale”, in cui sono indicati vincoli e criteri di priorità per la scelta delle piante da inserire nell’elenco;

Tabella 1 - Vincoli per la classificazione delle piante monumentali

Deroghe a V1, V2 e V3 potranno essere ammesse con specifica motivazione

Tabella 2 – Criteri di priorità per la classificazione delle piante monumentali

- la raccolta di tutti i censimenti realizzati nel Veneto in più di un ventennio di attività da parte di vari Enti e Associazioni e avvio della selezione per l’elenco regionale da questo materiale raccolto; - l’istituzione del tavolo provinciale che consente di poter disporre della competenza e della conoscenza del territorio che di chi, per lavoro o per passione, percorre quasi quotidianamente le aree dove vegetano gli alberi da selezionare; - accanto all’elenco degli alberi monumentali sarà redatto un elenco di alberi notevoli. 174 International Congress on The Trees of History

4. Problematiche emerse Le difficoltà finora incontrate nello sviluppo delle fasi di lavoro possono essere brevemente sotto elencate: 1. Mancanza di documenti normativi nazionali di riferimento per la classificazione di piante di pregio e per la omogeneizzazione della metodologia di rilievo e censimento Infatti, se da un lato è consolidata l’opinione che l’albero monumentale è un bene ambientale, meritevole di conservazione e tutela, ancor oggi si deve purtroppo constatare che a livello normativo nazionale le cose non sono ben chiare o per lo meno sussiste un approccio ancora approssimativo legato a criteri di catalogazione non esplicitati e codificati in maniera univoca per tutti. Ad oggi infatti, non è stato ancora proposto alcun protocollo operativo ufficiale, a livello nazionale, sulle modalità di individuazione, di censimento, di catalogazione e di gestione degli alberi monumentali, lasciando alle amministrazioni locali piena libertà sull’organizzazione del lavoro. Il Decreto Legislativo n. 490 del 1999, così come il recentissimo Codice dei Beni culturali e del Paesaggio (art. 10 punto 4 lett. f), pur sancendo l’importanza del patrimonio ambientale e paesaggistico, non considera esplicitamente l’elemento “albero” come un bene monumentale da conservare nonostante presenti un indiscutibile valore storico, estetico, paesaggistico, ambientale. Inoltre, l’attuale scheda “Parchi e Giardini” proposta dal Ministero per i Beni Culturali e Ambientali (Istituto Centrale per il Catalogo e la Documentazione, 1994) inquadra il bene parco o giardino, senza però considerare adeguatamente gli alberi quali principali elementi vegetali che compongono e determinano il valore stesso del parco. Infine, anche se vengono comunemente classificati alberi monumentali quelle piante imponenti che suscitano meraviglia per unicità ed armonia, caratterizzate da longevità e dimensioni notevoli, da forma o portamento molto particolari e rare, da essere considerate rarità botaniche o collegate con edifici storici o monumentali, con fatti storici, tradizioni o leggende, manca una metodologia standard di rilievo valida ad ampia scala; pertanto non è possibile, o risulta difficile, fare confronti fra diverse realtà territoriali. Questo permetterebbe di avere un approccio oggettivo alla catalogazione del bene da tutelare, slegato da criteri soggettivi ed emotivi di valutazione, soprattutto nei casi di alberi che già sottostanno a vincoli o che richiederebbero finanziamenti per interventi di manutenzione. 2) La legge non prevede le modalità di applicazione del vincolo Una volta realizzato il primo elenco regionale degli alberi monumentali, sarà necessario individuare le modalità di applicazione del vincolo. 3) Difficoltà a reperire finanziamenti e specifici contributi per gli interventi sia di tipo fitosanitario che di messa in sicurezza degli alberi monumentali Nella legge regionale del Veneto n. 20/2002 per la tutela e valorizzazione degli alberi monumentali non sono previsti contributi specifici per la valorizzazione degli esemplari monumentali individuati nell’apposito elenco. Questo aspetto è molto delicato in quanto la pianta monumentale può essere vista non come un pregio bensì come un onere dal singolo proprietario o amministrazione comunale, impossibilitati spesso a far fronte alle spese di manutenzione, restauro e messa in sicurezza. Quando l’elenco degli alberi monumentali verrà pubblicato nel Bollettino Ufficiale della Regione ed il vincolo di tutela diverrà quindi effettivo, sarà indispensabile poter disporre di un finanziamento per l’esecuzione degli interventi di messa in sicurezza degli alberi.

5. Conclusioni La finalità del lavoro promosso dalla legge regionale del Veneto sulla tutela e valorizzazione degli alberi monumentali è quella di far prendere coscienza di questo enorme patrimonio naturalistico ai cittadini veneti. La tutela e conservazione sono, in un’ottica di sviluppo sostenibile e valorizzazione delle risorse ambientali, i primi e basilari strumenti per trasmettere alle generazioni future l’importanza e il rispetto di tale patrimonio. Solo così ogni cittadino si potrà impegnare in prima persona per difendere questi giganti della storia e potrà essere direttamente coinvolto in azioni di promozione e divulgazione relative alla conoscenza e al significato storico-culturale del patrimonio arboreo paesaggistico regionale. Infine, sarebbe auspicabile che i contributi di studio e il know-how prodotti dalle singole regioni potessero confluire in un unico lavoro di sintesi a livello nazionale con individuazione e definizione di criteri e metodologie organiche di catalogazione; ciò potrebbe servire alla conservazione e gestione delle piante di pregio, al controllo fitosanitario e alla messa in sicurezza nonché, forse, ad un’eventuale pianificazione dei finanziamenti necessari per gli interventi. Torino, April 1st - 2 nd, 2004 175

6. Bibliografia di riferimento AA.VV. 1990. Gli alberi monumentali d’Italia: il Centro e il Nord. Ed. ABETE, Roma. AA.VV. 1991. Grandi alberi e monumenti naturali nel Friuli-Venezia Giulia. Regione Autonoma del Friuli Venezia Giulia, Az. Parchi e Foreste Regionali, pp. 223. Corona P., Salbitano F. 2001. Aspetti progettuali e di gestione delle alberature urbane. EM - Linea Ecologica 33(3): 11-25. Credano V., Pirola A. 1975. La vegetazione della Provincia di Sondrio. Amm. Provinciale Sondrio, Banca Credito Valtellinese, Sondrio. Dalla Fior G. 1985. La nostra flora. Ed. G.B.Monauni, Trento 1985 Fenaroli L. 1967. Guida agli alberi d’Italia. Ed. Marcello, Milano. Gellini R. 1985. Botanica forestale (Testi I e II). Ed. CEDAM, Firenze Hageneder F. 2001. Lo spirito degli alberi. Ed. Crisalide, pp. 439. Harrison R.P. 1982. Foreste. L’ombra della civiltà. Garzanti, pp.300. Pignatti S. 1982. Flora d’Italia. Edagricole, Bologna. Provincia di Brescia. 1996. Alberi monumentali della provincia di Brescia. Il Verde Editoriale, Milano. Provincia di Brescia. 1996. Censimento degli esemplari arborei monumentali del territorio della provincia di Brescia da sottoporre a tutela ex L.R. 30.11.83 n.86. Il Verde Editoriale, Milano. Provincia di Milano. 1996. Censimento degli esemplari arborei monumentali del territorio della provincia di Milano da sottoporre a tutela ex L.R. 30.11.83 n.86. Settore Ufficio del Piano, Milano. Regione Emilia-Romagna. 1991. Alberi monumentali dell’Emilia-Romagna – Censimenti e tutela (Volume n.43). Assessorato Ambiente/Istituto Beni Culturali, Bologna. Regione Lombardia. 1997. Direzione Generale Tutela Ambientale. Criteri e metodi per il censimento degli alberi monumentali – Documento tecnico. Milano. Semenzato P. (a cura di) 1999. Il verde storico. Teoria e tecnica di conservazione e restauro. Regione Veneto, Direzione Cultura e Az. Reg. Veneto Agricoltura, pp. 102.

Summary This paper outlines the importance of veteran trees under the naturalistic, cultural, social and landscape point of view. Then, it is referred the aim of the regional law for defence and protection of veteran trees and the methodology proposed by the Regional Agency “Veneto Agricoltura” to arrange the veteran tree list for the Veneto Region. Problems faced during the work development are presented and discussed. 176 International Congress on The Trees of History

IL SISTEMA REGIONALE PER LA CONSERVAZIONE DELLA NATURA. LA TUTELA DEGLI ALBERI MONUMENTALI E LA CONSERVAZIONE DEL PAESAGGIO IN PUGLIA M. Saccomanno Ufficio Parchi e Riserve Naturali, Assessorato all’Ambiente Regione Puglia

La tutela del patrimonio di alberi monumentali assume una particolare rilevanza in Puglia in relazione ad alcune specificità. Da un lato la regione appare essere quella con la più bassa percentuale di boschi (149.400 Ha pari al 7,75% della superficie regionale), dall’altra la sua posizione geografica gli ha conferito nel tempo un notevole patrimonio di biodiversità. La Puglia è definita infatti regione delle dieci querce, due delle quali appaiono esclusive della nostra regione (Quercus trojana webb, Quercus macrolepis), ospita con la foresta Umbra, la più estesa formazione di latifoglie in Italia (circa 15.000 Ha), presenta estese formazioni di Pinus halepensis. Il carattere determinante della pianura e delle limitate pendenze ha favorito nei secoli la forte riduzione del manto forestale, la cui presenza è testimoniata oggi proprio da vetusti alberi isolati. La tutela di tali esemplari viene operata attraverso il Decreto legislativo 29 ottobre 1999, n° 490 “Testo Unico delle disposizioni legislative in materia di beni culturali e ambientali” che agisce nei casi in cui vi è anche un valore storico del contesto di inserimento e dalla normativa regionale L.R. n° 14 del 31-05-2001 Art. 30 “Tutela paesaggistica degli alberi” che prevede la istituzione di un albo regionale dei monumenti vegetazionali. Per gli esemplari dell’albo è previsto il divieto di espianto e un regime sanzionatorio per gli abusi. La L. R. n.19 del 24-07-1997 “Norme per l’istituzione e la gestione delle aree naturali protette nella Regione Puglia” prevede altresì all’art. 2 - “Classificazione delle aree naturali protette” l’istituto dei monumenti naturali. Le azioni svolte sinora hanno riguardato una prima fase di conoscenza, favorita dalla diffusione di una scheda di censimento e successiva valutazione e validazione delle segnalazioni pervenute agli uffici regionali. Si sta procedendo inoltre ad un raccordo con altri enti (CFS, Ispettorati Forestali regionali) per l’azione di tutela e ulteriore indagine. La problematica della tutela degli alberi monumentali non riguarda solo le specie di interesse forestale, lo dimostra il caso del commercio ed espianto degli ulivi in Puglia. Si tratta di un caso complesso per due motivi: da una lato le dimensioni del problema, dall’altro l’importanza economica della coltura dell’olivo nella regione. In Puglia ci sono oltre 350.000 Ha coltivati ad ulivi, pari al 25% della superficie regionale. Sono interessati tutti i comuni della regione. L’ulivo è il simbolo stesso del paesaggio pugliese. L’ulivo, specie originaria del medio oriente, mostra i primi segni della sua presenza in Puglia in ritrovamenti preistorici tra Torre a Mare e Fasano (sud della provincia di Bari) risalenti al Neolitico, in periodo databile a circa 5000 a.C. Per avere un’idea dell’importanza dell’ulivo nella cultura regionale basti pensare che le antiche monete, gli stateri e le dracme tarantine del VI-V sec. a.C., riportano l’effige di satiri coronati d’ulivo. La presenza dell’ulivo si sostanzia in Puglia anche nei numerosi frantoi ipogei di epoca remota, attraverso la cui analisi è stato possibile verificare come avveniva sin da tempi lontanissimi la spremitura delle olive. Secondi i dati del 2000 l’olivocoltura pugliese produce un reddito di 760 milioni di euro all’anno. Vi sono cinque D.O.P. di produzione e la sua importanza è tale che sono stati realizzati quattro grandi itinerari turistici denominati vie dell’olio. Sono attivi 1200 frantoi, che trattano le 53 diverse varietà di olive coltivate in regione. Vi sono 50 milioni di piante di ulivo in Puglia, di questi circa 15 milioni di esemplari sono censiti come ultracentenari e si può certamente stimare un numero non inferiore ai tre milioni di esemplari pruricentenari e dotati di particolare valore paesaggistico ed estetico. La notevole longevità dell’olivo, con esemplari che in Puglia raggiungono i duemila anni, sembra legata in parte all’estrema capacità rigenerante della specie , in grado di rinascere dal tronco reciso, cosi come dai robusti germogli che si affacciano anche dalle parti più “antiche” dell’ albero. Le aspre condizioni climatiche caratterizzate da aridità, un difficile substrato con roccia affiorante a pochi centimetri dalla superficie, la frequenza degli incendi, il delicato equilibrio tra metabolismo dell’albero e potature, conferiscono agli esemplari di età più avanzata un alternarsi di legna secca dall’aspetto pitreo e vasi turgidi, ricche di linfa, diretti alle parti in vegetazione. Il risultato è un’insieme di sculture viventi dall’aspetto fortemente suggestivo. Ma questi caratteri di rusticità e di adattabilità, se da una lato ci hanno consegnato una pregevole eredità paesaggistica ed economica, dall’altra si stanno traducendo in penoso rischio di impoverimento del paesaggio pugliese, per la relativa facilità Torino, April 1st - 2 nd, 2004 177 dell’espianto e della vendita degli esemplari più pregevoli esteticamente. Nonostante l’impegno di istituzioni e cittadini la Puglia perde giornalmente significativi pezzi della sua identità. Ulivi secolari si acquistano, spendendo dai 2 a 8-10 mila euro a pianta, e vengono richiesti per arredare i giardini del nord Italia e dell’Europa centrale. Le dimensioni del problema determinano la estrema difficoltà di schedatura di tutti gli esemplari rappresentativi e la complessità di varare norme che vietino l’espianto senza confliggere con le esigenze produttive e con il diritto dei proprietari. L’unica normativa di riferimento è una vecchia legge emanata da Umberto II: il decreto legislativo luogotenenziale n. 475 “Divieto di abbattimento di alberi d’olivo” del luglio 1945. La norma è nata nell’immediato dopoguerra per limitare la tendenza all’espianto di ulivi per ricavarne legna da ardere, con il fine di tutelare la produzione. La norma prevede il divieto di abbattimento di alberi di olivo oltre il numero di cinque ogni biennio, tranne in caso di morte fisiologica degli alberi, permanente improduttività o eccessiva fittezza dell’impianto. Attualmente si stanno perseguendo due vie per la tutela di questo patrimonio. Una di analisi e raccolta dati per una maggiore comprensione del problema, l’altra di maggiore sensibilizzazione della popolazione e di raccolta dei dati. I primi risultati mostrano che gli ulivi pluricentenari sono raramente presenti in forma isolata, più spesso sono raccolti in appezzamenti agricoli piuttosto omogenei. E’ il caso di Mass. Pettolecchia, nei pressi di Fasano (Br) dove è stato messo in evidenza che vi sono 3000 ulivi pluricentenari, alcuni dei quali millenari, in una relativamente ridotta superficie aziendale. Tali aree possono comunque essere messe in evidenza con l’uso di ortofoto carte, grazie al caratteristico sesto di impianto irregolare, che una volta individuato può essere verificato attraverso l’analisi diretta dei siti. Resta da definire il modo con il quale intervenire sotto il profilo normativo per tutelare questi particolari paesaggi produttivi. Per una maggiore azione di sensibilizzazione si sta procedendo con la creazione di una scheda di censimento specifica per l’ulivo. Infatti i caratteri morfologici che individuano le specie di interesse forestale (diametro del tronco, altezza dell’albero) non si adattano all’ulivo. La nuova scheda si basa piuttosto su alcune caratteristiche del tronco (forma spiralata, aspetto dell’apparato radicale, ecc.). Con questo sistema sarà facilitata l’individuazione degli esemplari isolati ed anche dei contesti più rappresentativi, accanto ad un’azione di sensibilizzazione dei cittadini. Non si tratta ancora della soluzione del problema, ma certamente di un’azione che riteniamo potrà portare in tempi medio-brevi ad una forte riduzione dell’espianto e traffico di pezzi del nostro paesaggio. 178 International Congress on The Trees of History

MONUMENTAL TREES AND RELICT VEGETATIONAL FORMATIONS OF THE PROVINCE OF MATERA: INTERVENTIONS OF PROTECTION AND VALUE INCREASE E.L. De Capua, C. Rugge

1. Introduction The former denomination “Lucania” of Regione Basilicata, evokes what once was the natural landscape of this Region, dominated by the forest (lucus) and testifying its ancient sylvan-pastoral origins. Also the lucanian forest landscape has suffered deep modifications through the ages. Nevertheless interesting traditions have remained intact, which are tightly connected to ancient uses and customs of the various civilizations that alternated in the territory at different times. They concern celebrations and cults devoted to trees. The presence of important forest resources, characterizing the Province of Matera, has stimulated different studies, in particular on the relict vegetational realities, being rare ones, as well as on the suggestive monumental trees that grow within its territory. Such natural resources, connected to their historical and cultural aspects, represent fundamental elements to build up an educational knowledge path about the environment, underlining the signs that the human and natural history have handed down to us. In order to reach this goal, the Province of Matera has started and extended a series of interventions, aimed at protecting and raising the value of the forest resource in general and in particular of the unusual patrimony represented by the monumental trees. These deserve to be preserved for their noteworthy scientific-cultural and aesthetical value, being, moreover, important testimonies of the native Italian wood patrimony.

2. History and cult of the tree in the province of Matera Traditions and historical references about forests and trees offer very interesting hints for the Lucanian territory and particularly for the province of Matera. The Greek civilization, that mainly concerned the Metapontino Plain, introduced new cults and religious forms, to be identified in the natural cycles. In the classical age trees were object of cult and “humanized”, as it happened for instance for Dafne, the mythical nymph transformed into laurel, or for the fantastic forests populated by splendid female divinities called Driadi. Already between the III and the VI century B.C., in the territory of Policoro (the ancient Heraclea), the first laws concerning forest matters were passed. They still represent the only document regarding the forest ecosystem in pre-Roman Age. Besides offering accurate indications on the type of environment at those times, these laws, written on bronze boards, enacted the obligation for farmers to replace the trees that had been cut along the Agri river banks with others of the same species. In this way the lands that were sacred to Dionisio and Atena would not be deprived of their natural beauties. In the Roman Age the cult of the Italic god Silvano was widespread in the valley of the river Sele. It was the god of the woods and the countryside, to whom Autumn propitiatory rites were devoted. In the following centuries, the reduction of the forest surface mostly concerned the hilly areas, that allowed better general conditions of life compared with the ones in coast and mountain areas. In particular in the Lucanian territory, the work of deforestation continued despite the special Law for the Basilicata passed in the 1904, better known as Zanardelli Law, aimed at somehow stopping the devastation of Lucanian woods. As in the rest of Italy, with the advent of Fascism, also in Basilicata the reforestation and realization of urban parks favored a progressive change of the forest landscape. In fact both the area of the Ionian coast and the one of the Materan hill, are dominated by the presence of artificial settings of conifers, with a prevalence of Pinus halepensis, replacing the natural formations merely reduced to relict evidence today. The ancient pagan cult linked to the wood and tree is still strongly felt today by Lucanian people and brought back to life through the celebrations of the “May”, celebrating the nuptial rite between the prince of the trunks (Quercus cerris) and its top (Ilex aquifolium).

3. Vegetational patrimony and monumental trees The natural environment of Basilicata shows extremely heterogeneous physical and biological characteristics to which different vegetational landscapes correspond: from the hilly to the mountain system, from the torrential basin to the duny environment and the damp zones, from the natural parks to the reservations, not to forget the artificial reforestations, the urban parks and the gardens. Torino, April 1st - 2 nd, 2004 179

The whole Region belongs to the Mediterranean climatic area, boasting the presence of almost all its vegetational Plains. Within the Lucanian territory, in fact, you can find groups of plants belonging to the thermo-Mediterranean Plain, that is strongly characterized by the presence of thermopile vegetation, in particular sclerofilles such as the oleo-lentiscetis and the Mediterranean pines. Or you can find vegetation belonging to the meso-Mediterranean Plain where you can easily see the Leccio (Quercus ilex) and the thorny Oak (Quercus coccifera). Moving from the valley of the Basento upward, these plains are overhung by the supra-Mediterranean plain, with its characteristic deciduous oak woods, and by zones belonging to the Mountain Mediterranean plain, where areas of forest with Abies alba grow. In particular in the Province of Matera important relict vegetational evidence has survived. The Wood of Policoro (Oriented Natural Reservation managed by the Province) represents the last remains of what was the luxuriant forest “maze of tall and deciduous trees “, described by Norman Douglas, in 1907, when the English writer measured, inside the “dense brushwood”, a lentisco having a three meter circumference. The present remains of the wood represent what is left of the two complexes called “wood of the Pantano soprano “ and “wood of the Pantano sottano”, that were, up to some decades ago, one of the widest plain forests in Southern Italy. It is a hydric wood linked to the Carici-fraxinetum angustifoliae, dominated by the ossifillo Ash tree, with the presence of numerous other species, among which the Rural Elm, the Farnia, the black Ontano, the Poplars and the Laurel. When not subjected to systematic wood culture interventions, this forest had arboreal specimens of considerable size, reduced to sporadic samples today. Different areas of the Province of Matera along the Ionian coast belong to the same context. Here important shrubby formations of the Mediterranean bush grow with a prevalence of juniper and lentisco. The latter is present at various stages, from the gariga to the tall bush, where the shrubby elements often exceptionally assume arboreal forms. Among these, numerous specimens could be considered monumental trees due to the exceptional sizes and the age, as well as their strange forms forged by the main wind, blowing from the sea. In the province of Matera, within the territory of the “ Teresa Forest “, isolated specimens of Juniperus macrocarpa, whose age has been assessed about 110 years, have been individuated. In the Materan Comune of Montescaglioso, within the area called “the Monks’ Olive-grove”, a small wood area of about half hectare still exists, mainly composed of specimens of Pinus halepensis. In this group, formed by numerous plants of more than one century, a specimen of over 110 years stands out. This specimen has got a trunk with a four meter circumference growing up to about three meters and splitting itself into two big branches of 70 cm of diameter each. Moreover there are numerous specimens of deciduous oaks, typical of the upper plain, of exceptional massive structure and longevity. Among the innumerable examples, a specimen of Quercus pubescens, growing in the place called “Calla” , in the Comune of Tricarico, stands out. Its age has been estimated to be 600 years. It seems to be the oldest plant in whole Lucania, having a height of 16 m. and a trunk circumference of 6,25 m. A further example of the extraordinary longevity of this specimen is in the area called “ Pocco Hill “ in Oliveto Lucano. The “Cersone”, as it is called by the inhabitants of Oliveto, is more than one hundred years, a height of 18 m. and a circumference of 5,30 m. Among the suggestive calanchis of the Comune of Pomarico, in the area of “ Melito Plain “, four stately specimens of Pinus pinea grow. Their age has been estimated to be about 160 years. They have a height of 30 m. and trunk circumference between 2 and 3.5 m. The following table sums up a list of the main plants having a particular naturalistic and landscape value to be protected according to the Regional Law n. 42 of 22-5-1980, passed with Decree by the President of the Regional Assembly of January 4 th 1988 n.3.

Tab.1 - List of the trees having major naturalistic and landscape value in the Province of Matera

Kind Common Place Età(anni) C1,30(cm) Htot Posizione Salix babylonica Aliano Acinello 25 175 14 isolated Tamarixgallica Matera Cilvestri 50 140 3,50 isolated Juniperusmacrocarpa Matera Forest Teresa 100 160 12 isolated Phoenixdactiliphera Matera BorgoLa Hammers 100 220 8 isolated Rhamnusalaternus Matera Forest Teresa 50 70 4 isolated Quercus trojana Matera Farm S.Francesco 100 150 12 in group Pinushalepensis Montesca-glioso Olive-grove deiMonaci 100 370 25 in group 180 International Congress on The Trees of History

Taxodium disticum Pomarico S. Felice 150 80 20 in group Quercus pubescens OlivetoLucano Calle lily Rocco 300 530 18 isolated Pinushalepensis OlivetoLucano Olive-grove / Accettura 50 270 18 isolated Trembling Populus OlivetoLucano Scarrone 50 115 14 in to spin Pinus pinea Pomarico Plan MelitoDemanio 150 307 30 in group Salyxbabylonica Salandra Villa 35 80 12 isolated Quercus pubescens Tricarico Calle lily 600 680 16 isolated

Fig. 1 An ancient Ceratonia siliqua in Montescaglioso (MT)

4. Interventions of protection and value raise

The Province of Matera intends to continue with the activity of preservation and value raise of its own forest patrimony, by promoting a series of scientific and historical - naturalistic studies aimed at defining the most appropriate ways of action and intervention. It has undertaken for a long time scientific and geo-historical studies on the relict woods and on the numerous monumental trees of the Province. The necessity of an interdisciplinary approach is of fundamental importance, also because of the complexity of the territory and the problems concerning the preservation of monumental trees. Such trees, being ancient and very big specimens, need phytosanitary analysis, to prevent deterioration to take place, and investigations about their stability. To such purpose the Province of Matera proposes to collect the necessary data for the management and application of the appropriate culture measures to adopt within a short period and over a longer one. The numerous activities and implications coming out around a monumental tree have given the idea for the institution of an Observatory on the relict woods and the monumental trees of the Province of Matera. Given the institutional role of the Province, the realization of informative didactic material on the monumental trees and what they represent is considered to be of fundamental importance. The idea of promoting the monumental tree areas with a series of initiatives connected to the local traditions is to be placed in the same context. So that the places and the selected trees will not remain a closed reality but a well known one that the public can enjoy, the realization of a suitable cartography is also essential. This will be followed by the realization, where possible, of a series of paths, conceived in such a way to focus the public attention on the important natural aspects and on the particularities that can be seen there.

Conclusions The structural and composition particularities of some woods contribute to define some communities of considerable naturalistic value and, as to the monumental trees, some rare examples of longevity and bulk, deeply connected to the culture and the popular traditions of the territory. The census of the monumental trees taken till today represents only a part Torino, April 1st - 2 nd, 2004 181 of the vegetational patrimony of the Province that needs to be analyzed with greater detail. The importance currently assumed by the monumental tree as a source of important anthropological –territorial information, requires an appropriate scientific and historical - geographical search to be spread. Having been recognized the essential value by now assumed by the environmental tourism, the natural resources currently represent a crucial expectation of the traveler. The relict woods and the monumental trees can represent, if correctly managed and protected, a precious resource also in the field of the ecotourism and a further opportunity for the smaller centers situated in the marginal territories of the Province.

Bibliography

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