Technical guidelines for genetic conservation and use European larch Larix decidua Larix decidua Larix Larix decidua Jan Matras1 and Luc E. Pâques2 1 Forest Research Institute, Warsaw, Poland EUFORGEN 2 INRA, Research Unit AGPF, Olivet Cedex France These Technical Guidelines are intended to assist those who cherish the valuable European larch 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 compete well with other trees. Larch species establish endur- ing and close stands only when European larch (Larix decidua climatic conditions eliminate Mill.) is one of the few decidu- their competitors, such as in the ous conifers. It is monoecious mountains. In the Alps, European and wind pollinated. Larch pol- larch grows best at an altitude of len is small and round without air 1400–1500 m, but faces strong bags. As a result it is transported competition from other species by the wind over only relatively that also grow well at this altitude, short distances of up to 300 m. e.g. silver fir (Abies alba Mill.)and Larch trees reach Norway spruce (Picea abies (L.) sexual maturity at the Karst). At higher altitudes larch age of 15 years in grows less vigorously but faces open stands but at less competition from other spe- the age of 35–40 years cies. At elevations above 1500m, in closed stands. Larch up to more than 2000 m, larch produces seeds every forms closed pure stands. In the 3–4 years on average. Tatra Mountains, larch does not Over 50% of larch seed form extensive pure stands but may be ‘empty’. Larix grows in compact clumps where decidua can eas- local conditions do not favour ily cross with some the growth of Norway spruce. other larch species, Larch grows on a wide range such as Japanese larch (Larix of soils. It grows best on deep, kaempferi (Lamb.) Carr. with well-structured and aerated soils, which it produces very valuable but can also grow on shallow hybrids. stony soils, including calcare- Larch is a typical pioneer, ous soils, with a medium ground colonizing open land on freshly water level. disturbed soils. As a light de- manding species, larch does not EuropeanLarix larchLarix decidua Europeandecidua larchLarix deciduaEuropean larch LarixLarix deciduaEuropean larch deciduaLarix deciduaEuropean larchLarix deciduaEuropean Larix larchLarix decidua Europeandecidua larchLarix deciduaEuropean larch LarixLarix deciduaEuropean larch Larixdec deciduaEuropean larchLa Distribution Importance and use Genetic knowledge European larch is a central Eu- European larch is economically European is one of the most re- ropean species occurring mostly important at regional level, espe- searched tree species in Europe. in mountainous regions (Alps, cially in mountainous areas such This is due to both its economic Sudetes and Carpathians). It is as the Alps. It has long been importance and social and cul- found on lowlands only in South valued for its wood and resin. It tural values. For example, in an- Poland ( wi tokrzyskie Moun- was already used as a con- cient times, larch, lime and oak Ś ę tains). Its natural range extends struction material in ancient were considered sacred. to about 500 000 ha and its dis- Rome. European larch has a high tribution is fragmented. Larch is one of the fast- level of genetic variability for People have planted Euro- est-growing conifer species most silvicultural traits both pean larch well beyond its na- in Western and Central Europe, between and within popula- tive range, particularly in Western producing more than 10 m3 of tions. International provenance Europe. Together with the Japa- wood per ha annually under op- experiments have indicated the nese and hybrid larches, planta- timal conditions. Because of its best larch populations in terms tions of European larch cover fast juvenile growth and its pio- of silvicultural quality. The fastest over 500 000 ha. neer character, larch has found growing populations were found numerous applications in forestry among the Sudetes and Cen- and agroforestry. It is used as a tral Polish larch; Alpine popula- ‘preparatory species’ to afforest tions were slowest growing. The open land, abandoned farmland populations from Central Europe or disturbed land and as a ‘nurse (Sudetes and Central Poland) species’ prior to the introduc- showed also the highest stability tion of more demanding species. across environments (low GxE), There is growing interest in its even across ecologically con- amenity value for forest land- trasting conditions, while south- scaping. western alpine larch populations Larch wood is dense, performed well only at high el- strong and durable. It evation sites. is used extensively in High variability was also the building industry found in resistance to canker dis- (houses, roof con- ease (Lachnellula willkommii (R. structions, bridges, Hartig.) Dennis), one of the most flooring, etc) and in harmful diseases in larch. Resist- furniture making. ance was highest in populations from the eastern Alps and lowest in populations from the southern Alps. Similar genetic differenc- es were found in traits such as seed weight, taper, crown shape, branching, wood properties, re- sistance to insects, frost hardi- ness and drought tolerance. EuropeanLarix larchLarix decidua Europeandecidua larchLarix deciduaEuropean larch LarixLarix deciduaEuropean larch deciduaLarix deciduaEuropean larchLarix deciduaEuropean Larix larchLarix decidua Europeandecidua larchLarix deciduaEuropean larch LarixLarix deciduaEuropean larch Larixdec deciduaEuropean larchLa Several countries have de- Threats to eas, have been established from veloped breeding populations of imported seeds. It is thus likely genetic diversity European larch through selection that natural populations have of plus trees in natural stands. The natural distribution of Eu- been crossed with introduced Trees from Sudetan origins and ropean larch is small and frag- material. central Poland have been widely mented and the species The species belonging to used because of their favourable is subject to two major the section of European characteristics. Progeny testing threats: shrinkage of the larch have separated quite is underway at the intra-specific native range and hybridi- recently and have not (usually from open pollination) sation with ‘alien’ germ- yet established barri- and inter-specific (from control- plasm. ers to crossing. Wide- led pollination with Japanese 1) Due to its pioneer spread introduction larch) levels. and shade-intolerant charac- of Japanese ter, natural occurrence and larch in Western regeneration of European and Central Europe larch are favoured by fre- at the turn of the 20th century quent natural -events in the high led to possible crossing of these mountains that either refresh the two species. As a result of further soil (such as land slides) or de- crossings, pure populations of stroy competing vegetation (such European larch in these areas as fire and snow slides). Chang- have been or may soon be com- es in human activities (abandon- pletely eliminated. ment of farmlands) during the last Finally, climate change is pro- century have also favoured the jected to lead to a migration of natural downward extension European larch populations to- of larch in the Alps. wards higher elevations, which in Now, however, some areas could seriously limit the native range their occurrence. of European larch is shrinking because of two factors: i) human intervention to re- duce the incidence of avalanche and landslide and fire, and ii) the lack of human interven- tion in newly colonised lands with intense competition by shade-tolerant species. 2) European larch has a long history of cultivation across Europe, dating from at least the 18th century. Many extant larch stands, especially in lowland ar- EuropeanLarix larchLarix decidua Europeandecidua larchLarix deciduaEuropean larch LarixLarix deciduaEuropean larch deciduaLarix deciduaEuropean larchLarix deciduaEuropean Larix larchLarix decidua Europeandecidua larchLarix deciduaEuropean larch LarixLarix deciduaEuropean larch Larixdec deciduaEuropean larchLa Guidelines for genetic are no rules preventing the use Ex situ conservation can be of alien material except in natural carried out through establish- conservation and use parks or reserves. ment of artificial gene conserva- The lack of natural regeneration European larch requires spe- tion units. These might include can be favoured at high elevation cial management if it is to survive plantations as part of breeding (e.g. over 1500 m in the Alps), with and flourish, especially in mixed programmes, such as clonal ar- protection against farm animals, forests. For example cutting, in chives, clone banks, seed or- soil scraping and complementary which trees from the upper sto- chards and field trials as well as plantation; at lower elevation the rey are left as shelter precludes specifically designed conserva- competition with shade-tolerant natural regeneration of larch. tion plots. Populations selected tree species should be control- Thus, the drawing up of gen- for ex situ conservation should led by thinning to favour larch