Italian Alder (Alnus Cordata)

Technical guidelines for genetic conservation and use Italian alder Alnus cordata Alnus cordata Aln Alnus cordata Fulvio Ducci¹ and Andrea Tani² ¹ CRA-ISSEL (Silviculture Research Centre), Arezzo, Italy ² Faculty of Forestry, University of Florence, Florence, Italy

These Technical Guidelines are intended to assist those who cherish the valuable Italian alder genepool and its inheritance, through conserving valuable seed sources or use in practical forestry. The focus is on conserving the genetic diversity of the species at the European scale. The recommendations provided in this module should be regarded as a commonly agreed basis to be complemented and further developed in local, national or regional conditions. The Guidelines are based on the available knowledge of the species and on widely accepted methods for the conservation of forest genetic resources.

Biology and ecology

Italian alder (Alnus cordata (Lo- isel) Desf.) is a monoecious, wind- pollinated tree. There are two recognized bo- tanical varieties: rotundifolia and genuina. The species reaches repro- ductive maturity at about 10-12 years of age. Flower buds appear in early summer, just before leaf buds burst, and flowering starts the following winter. Male flowers contain 5-6 catkins. The female catkins are axillary to male catkins and develop into pseudo-cones. These ripen during the winter, turning from green to brown, and open the following spring. The seed is wind-dispersed. Buds and pseudo-cones are the largest among alders. Leaves are typically heart- shaped. In spring, bud-burst occurs relatively late. Leaves ItalianAlnus alderAlnus cordataItalian aldercordataAlnus cordataItalian alderAlnus cordata ItalianAlnus alderAlnus cordataItalian aldercordataAlnus cordataItalian alderAlnus cordata ItalianAlnus alderAlnus cordataItalian cordataalderAlnus cordataItalian alderAlnus cordata AlnusItalian alderAlnus cordataItalian c alderAlnus cordata

commonly remain green after Distribution Importance and use the first frosts of winter and per- sist until the end of December. Italian alder grows at alti- Italian alder is found in small Italian alder is a fast-growing, tudes of 200 m (on northern areas of the southern Apennines multipurpose species that can slopes) to 1600 m, depending on (Basilicata, Calabria and Cam- also improve soil fertility though rainfall and temperature. It can pania) and mountains in north- symbiotic nitrogen fixation with reach a height of 25 m or more in eastern Corsica. Both varieties Actinomyces alni (Frankia alni). natural forests, with stem diam- (rotundifolia and genuina) grow It is grown as an ornamental eter of more than 65 cm at breast in southern Italy whereas only tree and also produces valu- height. Italian alder is a heliophil- rotundifolia is found in Corsica. able wood. The dried flower in- ous pioneer species and it can dustry uses the pseudo-cones rapidly colonize gaps created by for Christmas floral ornaments. felling in beech (Fagus sylvatica) In mountainous areas, and chestnut (Castanea sativa) it is planted for soil stands. This allows the species protection. In recent to develop pure stands. It is also decades, Italian alder able to invade black pine (Pinus has been widely used, in Italy, nigra) stands in wet conditions. as a shelter species with wal- Adventitious buds commonly nut (Juglans regia), wild cherry survive on stumps after forest (Prunus avium) and other no- fires and are able to produce ble hardwoods in intensive for- shoots very quickly. est tree-farming programmes. In Italian alder will grow on most France, the potential of this spe- soils, but planting in clay soils cies for biomass production is should be avoided. being considered. Alder timber is reddish-or- ange, with relatively wide an- nual rings resulting from the fast growth typical of the species. In general, the quality of the timber is similar to that of hy- brid poplar, although it is heavier, shrinks much more and has high modulus of rupture. The timber breaks down rapidly when exposed to air, but is durable when immersed in water. The timber is used for turning and carving as well as for the production of moulding, furniture, panelling and plywood. ItalianAlnus alderAlnus cordataItalian aldercordataAlnus cordataItalian alderAlnus cordata ItalianAlnus alderAlnus cordataItalian aldercordataAlnus cordataItalian alderAlnus cordata ItalianAlnus alderAlnus cordataItalian cordataalderAlnus cordataItalian alderAlnus cordata AlnusItalian alderAlnus cordataItalian c alderAlnus cordata

Genetic knowledge Threats to severely damaged near their low- genetic diversity er altitude limits. Climate change could also result in a reduction in Studies on intra-specific varia- Despite its limited natural range, genetic diversity through loss of tion have pointed out that ge- Italian alder is not considered an suitable habitats. Other threats netic diversity at individual level endangered species. It has expe- are connected with competition is very high. However, compar- rienced little human intervention, with beech and other species ing Italian populations, variation largely because it grows over and the isolation due to reduc- in morphological traits, such as a wide range of elevations and tion and/or absence of geneflow leaf size and leaf shape, is small. can spread very rapidly. Natural between populations. Comparisons of growth rate have regeneration occurs readily and The nursery system may also never shown large differences in seedling growth is rapid in clear contribute to the reduction of more than 30 years of observa- cuts or gaps in forests. Moreo- diversity variability in new plantations in provenance trials. ver, most of its natural range oc- tions, if seed collection activities In spite of the small species curs within protected areas. are based on only a very few range area in Italy, the absence The most important threats mother trees. of natural barriers allows the pol- to Italian alder diversity are the len and the seeds to maintain tree’s limited natural range, the sufficient gene flow to prevent reduction of clear cutting in differentiation among popula- mixed forests and in protected tions. Studies, including Corsi- areas, unauthorized grazing in can populations, show consid- forests and the isotherm shift in erable differences compared to the Mediterranean region due to Italian alder: these populations climate change. The increase in are more resistant to drought temperature may force beech–al- than the Italians ones. der ecosystems to shift to higher Self-pollination proved to be elevations. As a result, large parts very low in controlled pollina- of populations tion experiments carried out in could disap- plantations aimed at obtaining pear or be full-sib progenies. This should be taken into account in the design of the seed orchards; ramets from the same clone must be planted as far apart as possible. . ItalianAlnus alderAlnus cordataItalian aldercordataAlnus cordataItalian alderAlnus cordata ItalianAlnus alderAlnus cordataItalian aldercordataAlnus cordataItalian alderAlnus cordata ItalianAlnus alderAlnus cordataItalian cordataalderAlnus cordataItalian alderAlnus cordata AlnusItalian alderAlnus cordataItalian c alderAlnus cordata

Guidelines for genetic by harvesting. nursery, where the micro-site conservation and use Seed should be collected factors should be appropriate from 30-40 well scattered trees for maximum seedling survival The first long-term action is to per seed stand. Nearly ripe and development. Extreme con- ensure the in situ conservation pseudo-cones should be col- ditions for the range required of existing populations accord- lected in mid-October and early by seedlings should be avoided ing to dynamic gene conserva- November to ensure that viable (pH, minerals, temperatures, tion criteria. Italian alder can be seeds material is ob- light, water supply, etc.) as these managed in high forest or tained. The pseu- may impose selection pressures coppice systems. High do-cones should which only allow those that are forest management be dried at 38-40°C best adapted to these conditions can be applied for 15-18 hours to survive. to mixed or pure and between 5 Seed collection should be stands. In both and 6% air hu- regularly rotated among several cases the best midity. stands, so that different popula- regeneration Seeds can be tions or subpopulations are sam- method for stored up to about pled. Similarly, different groups Italian alder 2-3 years at 5-7°C of trees within a stand should is the crea- and 5-6% air humidity. be used for successive collection of small Indeed, concerning the tions. Stands should be selected clear cuts seed preparation and pre-treat- across a range of altitudes to en- or strips (e.g. ments, precise temperature and sure that the full range of genetic 20 x 200 m). The best results moisture requirements during the variation is captured. for regeneration are achieved seed extraction and conserva- Seedlings should be planted where mineral soil is exposed, tion should be met (temperature on a site that matches the re- i.e. when top soil layers are for between -3° and +3°C and mois- quirements of the species. This some reason disturbed by ero- ture of the seed-bed between will help ensure seedling survival. sion or ‘ploughed’ by animals or 5 and 7%), as well as chilling Seedlings should be carefully la- by humans. A typical situation conditions (±5°C and 70-80% belled to ensure that is represented on slopes along moisture) should be carefully their origin can roads where light is plentiful and supplied. This process should be traced, and mineral soil is accessible. Es- induce a prompt, complete and should be the pecially in mixed stands, small quick germination of all seeds. species includ- subpopulations or 10-20 trees In this way, possible selective ed in the official should be used as seed trees on micro-environmental list of species of clear cuts and strips. effects will be re- the European direc- In mixed beech-alder cop- duced and most tive on forest reproduc- pices, standards of Italian alder of the ge- tive material trade. are usually allowed to develop to netic variation Results of several provide seed for growing natural present in the controlled pollination ex- regenaration, by taking advan- seed lots will periments showed that seed tage of suitable light conditions, be maintained. orchards should not be based of the more rapid partial minerali- A similar stra- on mixtures of populations. zation of the litter and of the soil tegy should be Seedlings from within-population mineral layers made accessible followed in the crosses performed better than AlnusItalian alderAlnus cordataItalian cordata alderAlnus cordataItalian alderAlnus cordata AlnusItalian alderAlnus cordataItalian cordata alderAlnus cordataItalian alderAlnus cordata AlnItalian alderAln

Distribution range of Italian alder

those from between-population crosses. Possible problems of inbreeding can be reduced in single-population seed orchards by the inclusion of adequate numbers of clones. AlnusItalian alderAlnus cordataItalian cordata alderAlnus cordataItalian alderAlnus cordata AlnusItalian alderAlnus cordataItalian cordata alderAlnus cordataItalian alderAlnus cordata AlnItalian alderAln

This series of Technical Guide- Selected bibliography lines and distribution maps were produced by members of the EUFORGEN Networks. The Magini, E. and M. Paci 1988. Comportamento al 12 anno di popolazioni diverse di ontano napoletano (Alnus cordata Loisel.). L’Italia Forestale e objective is to identify minimum Montana LXIII (5): 111–127. requirements for long-term genetic conservation in Europe, Mannucci, M. 1995. Il legno di ontano. Sherwood 7: 21-24. in order to reduce the overall Paci, M. and A. Tani 1995. La ricerca sull’ontano napoletano: il punto della conservation cost and to improve situazione dopo oltre vent’anni di osservazioni. Sherwood 6: 15–21. quality standards in each country. Paci, M. and A. Tani 1995. La ricerca sull’ontano napoletano: il punto della situazione dopo oltre vent’anni di osservazioni (seconda parte). Sherwood 7: 13–20. Gamisans, J. 1983. L’aulne à feuilles en coeur (Alnus cordata Loisel.) dans son milieu naturel en Corse. Revue Forestiere Francaise 30 (6): 445–442. Prat, D. 1998. Alnus cordata – Aulne à feuilles en cœur. En: Les ressources Citation: Ducci F. and A. Tani génétiques forestières en France. Tome 2: les feuillus (M. Arbez et J.F. 2009. EUFORGEN Technical Lacaze, eds.). Bureau des ressources genetiques, INRA, Paris, France. Guidelines for genetic conser- pp 33–36. vation and use of Italian alder (Alnus cordata). Bioversity Inter- national, Rome, Italy. 6 pages.

ISBN 978-92-9043-786-4

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