Acer Campestre

Technical guidelines for genetic conservation and use Field maple Acer campestre

László Nagy1 and Fulvio Ducci2 1 Forest Research Institute, Sárvár, Hungary EUFORGEN 2 CRA, Forest Research Institute, Arezzo, Italy

These Technical Guidelines are intended to assist those who cherish the valuable field maple 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

Field maple (Acer campestre L.) is a mid-sized deciduous tree of the Platanoidea section. It is a diploid species with a chromo- some number of 2n=26. Although the flowers are mor- phologically hermaphroditic, owing to the reduction of one of the sexes they are functionally unisexual. Dominantly male or female individuals are often observed. Field maple is insect pollinated and at least partially capable of self- pollination. Flowering usually starts in late April, either simulta- neously with, or several days before, bud burst. In the lower elevations of the Mediterranean region, bud burst may start in March. The winged seeds ripen in late September and are dis- persed by the wind from mid- October on. As seed dormancy lasts at least one year, natural germination usually takes 18 months. During their early years, Acereld mapleAcer campestre campestreField mapleAcer campestreField mapleAcer campestreField A m

seedlings tend to develop their Distribution Importance and use root system and shoot elonga- tion is limited. Well-established, 5- to 8-year-old seedlings begin The natural distribution of field The scientific name Acer rapid growth that lasts for about maple covers most of Europe. campestre presumably origi- 25 years. The height of mature The latitudinal distribution nates from Italy, where, especial- trees rarely exceeds 20 m, ranges from 55°N to 38°N, from ly in Tuscany, field maples although exceptional specimens central and southern England, together with elms were planted can reach almost 30 m in height southern Sweden and Denmark in the fields and vineyards as liv- and 90 cm in diameter, and live to the Pyrenees, Sicily, Greece ing props for grapevines, and 250–350 years. and northern Turkey. Isolated considered an important element After reaching reproductive occurrences can be found in of the landscape. maturity at an approximate age Spain and North Africa. Field Field maple rarely produces of 20 years, this species is prolif- maple reaches its eastern limits timber-sized trees. When size- ic and a regular seed disperser. in the Voronezh Region in Rus- able timber is available, it is used As field maple has notable vege- sia, in the Crimean Peninsula, in for cabinetry, turnery and carv- tative capabilities, it quickly the Caucasus and at the south- ing. Regrettably, it is mostly used recovers from stem injuries and ern shores of the Caspian Sea. as firewood and pulpwood due branch system damage, and Field maple usually grows at to the small dimensions and low coppices vigorously. lower elevations, extending up to quantities produced, although its The field maple has a very 800 m a.s.l. in Bavaria, 1400 m valuable wood deserves more wide ecological range. The trees in Switzerland and 1800 m in the attention. Its timber is the hard- prefer warmer climates but are Caucasus. est and has the highest density also winter hardy and tolerate Its excellent social capabili- among the European maples, temperature extremes of conti- ties make field maple one of the being fine-grained, tough, elastic nental sites. Field maple has a most characteristic mixed and hard to split, moderate water need and avoids species of the Central and East with a pale red- waterlogging, favours calcareous European broad-leaved forests. dish or brown- soils but also grows well on Usually found in the lower ish tint and a heavy clay and is able to subsist canopy, it has an important role silky shine. on soils with a pH lower than 6 or in formation of the vertical struc- Pith flecks are higher than 8. However, growth ture of xerothermic oak forests, frequent. The and lifespan are very limited gallery forests and Mediter- timber of the under these conditions. It is ranean shrub vegetation. In the roots is often extremely shade-tolerant during arid lowlands, field maple is bunched and the first decade, but light require- often found in codominant posi- is valued for ments are higher in seed-bearing tion with oaks, while in humid small objects years. areas or higher elevations it has of fine craftwork. only a limited competitiveness The bark is and is nearly overcome in beech slightly anticholes- and hornbeam mixed forests. terolemic and astrin- gent; a bark decoc- tion has been used to bathe sore eyes. The AcermapleAcer campestreField campestre mapleAcer campestreField mapleAcer campestreField Field A m

sap contains some sugar and Genetic knowledge management techniques and can be drunk or boiled into habitat destruction do not affect syrup. The sugar content is con- the genetic constitution of field siderably lower than in sugar Information on the species’ maple in most of its distribution maple (Acer saccharum) sap. genetic resources is very scarce area. Field maple is a melliferous plant due to a lack of extensive genet- with good honey and honeydew ic studies. yield. It has limited ornamental Field maple is a taxonomical- importance, but when ly divided species. Its intraspe- used in hedges, it cific classification is based on bears trimming and morphological, phenological drastic pruning and, partially, ecogeographical quite well. characteristics. Genetic differen- tiation is presumed from the high morphological polymor- phism and its very wide ecological range. The species’ reproductive characteristics— such as insect pollination, partial self-compatibility, limited seed dispersal and good vegetative capabilities—may lead to higher between-population variation compared with other widely dis- tributed species. In addition, the observed separation of functionally unisexual flowers (even specimens) and their segregation to more or less distinct flowering phases, substantially limits the possibility of random mating. Owing to the low economic importance of field maple, human impact on its genepool is fairly low. The genetic structure of the populations, the range, distribution and ecogeographical pattern of the genetic variation is presumably close to the natural state. Long-distance transfer of reproductive material, aggressive AcermapleAcer campestreField campestre mapleAcer campestreField mapleAcer campestreField mapleAA

Threats to Guidelines for genetic genetic diversity conservation and use

On a pan-European scale, field Given the presumed good maple is not endangered at overall status of the genet- species level. This species ic resources and the limit- seems to maintain persistently ed value of field maple, a almost the same distribution low-intensity in situ con- area. Stress caused by human servation approach is influence, biotic and climatic fac- advised. tors, including sudden changes An efficient conservation in site conditions, is considered programme requires substantial fairly low. Hybridization pressure genetic knowledge of the target is negligible, with a slight possi- species. In order to obtain this The marginal regions bility of crossing with ornamental knowledge, inventories and should also be represented. varieties near populated areas. genetic studies are needed to In the case of endangered, frag- However, this species might assess the existing genetic diver- mented or small populations, and be endangered at the population sity and its distribution. As this stands growing under special level. In spite of the existence of information is lacking, several conditions or carrying unique fea- long-range pollen transfer mech- general measures are described tures, ex situ collections should anisms, the effective size of mar- below. supplement the network of con- ginalized populations might be With regard to the different servation units. These collections too small to maintain sufficient ecological conditions within the should be established from prop- genetic diversity. In certain cases, natural distribution, a network of agation material obtained within field maple has suffered from at least 30 in situ conservation the same ecological region, competition in gallery forests units, each with more than 50 should be designed to avoid with invasive species like Acer unrelated, flowering and seed- inbreeding and be preferred for negundo or Fraxinus pennsylvan- dispersing specimens, is needed use as seed sources. ica. It also has suffered from habi- to capture the existing adaptabil- Maintaining the landscape tat destruction and changes in ity. This network should evenly function of field maple in vine- land use, especially in the lower cover the whole distribution area, yards could be an efficient forest zone. as well as the ecological variation approach for on-farm conserva- of the occurrences. tion in agricultural areas. In order to enhance efficien- cy, the network might include existing conservation areas, seed stands, breeding collections and conservation units of other species (e.g. oak, beech, other noble hardwoods), as long as the management practices and measures do not hinder the conservation of field maple genetic resources. AcerField mapleAcer campestre Fieldcampestre mapleAcer campestreField mapleAcer campestreF

Distribution range of field maple eField Acer mapleAcer campestreField campestre mapleAcer campestreField mapleAcer campestreField EUFORGEN

These Technical Guidelines were Selected bibliography produced by members of the EUFORGEN Noble Hardwoods Network. The objective of the Net- Bendixen, K. 2001. Zum Reproduktionssystem des Feldahorns (Acer campestre L.): Blühphänologie und genetische Untersuchungen. Disserta- work is to identify minimum genet- tion, Georg-August-Universität Göttingen, Germany ic conservation requirements in Fenaroli, L. and G. Gambi. 1976. Alberi, Dendroflora italica. Museo Tridentino the long term in Europe, in order di Scienze Naturali, Trento, pp. 541–544. to reduce the overall conservation Hoffmann, E. 1960. Der Ahorn: Wald-, Park- und Straßenbaum. VEB Deutsch- cost and to improve the quality of er Landwirtschaftsverlag, Berlin. standards in each country. Leinemann, L. and K. Bendixen. 1999. Inheritance of isozyme variants in field maple (Acer campestre L.). Forest Genetics 6(2):73-77. Van Gelderen, D.M., P.C. de Jong and H.J. Oterdom. 1995. Maples of the World. Timber Press Inc., USA.

Citation: Nagy, L. and F. Ducci. 2004. EUFORGEN Technical Guidelines for genetic conservation and use for field maple (Acer campestre). International Plant Genetic Resources Institute, Rome, Italy. 6 pages.

ISBN 92-9043-664-6

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