Technical guidelines for genetic conservation and use European white Ulmus laevis

Eric Collin CEMAGREF, Nogent-sur-Vernisson, France EUFORGEN

These Technical Guidelines are intended to assist those who cherish the valuable white elm genepool and its inheritance, through conserving valuable 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

White elm (Ulmus laevis Pall.) is allogamous, and does not hybridize with the other Euro- pean elm species which belong to a different sec- tion of the genus. are hermaphroditic and wind pollinated. Gen- eration time is short and seed production is regular and prolif- ic, with a high per- centage of viable seed and high germination rates. dispersed by wind or carried downstream by rivers enable the colonisation of new sites. Root suckering may play a role in the regeneration of established stands whereas stool sucker- ing is thought to be poor. The typical habitat of the white elm is riparian forest, where it can tolerate pro- longed flooding for longer periods UlmusEuropean white elmUlmus laevis Europeanlaevis white elmUlmus laevisUlmuEuropean white elm

and withstand lower tempera- Distribution Importance and use tures than the field elm (U. minor Mill.), with which it is often asso- ciated. Although it is typically White elm is distributed across White elm is of low economic found in moist sites, it can toler- central and eastern Europe, from value and unlike other European ate moderately dry, deep soils the Ural Mountains to eastern , the timber is not prized. and it is also found as a compo- France, and from southern Fin- The cross-grained wood causes nent in wooded steppe environ- land to the Caucasus and Bosnia. difficulty in machine cutting and ments. Along with field elm, the Since it is relatively rare and often defects. Wood density is lower white elm is sporadically found in confused with the other two elm than in other elm species, and it mixed oak forest. It is not found species indigenous to Europe, its produces poor quality firewood. on mountainous sites and distribution in southern France However, due to its fast growth, prefers altitudes of less than 300 and northern Switzerland has ornamental value, and tolerance m. In forest stands, it is a second been underestimated in the past. to soil compaction, de-icing salts storey , and in the open it can It must still be confirmed if small and , white elm has reach heights of 35 m. Individual riparian populations recently long been used for amenity rarely live longer than 200 discovered in southern France plantings in towns and on road- years, but have been recorded are autochthonous or estab- sides. It is rarely affected by as old as 300. lished aliens. Natural populations (DED) in of white elm are not western Europe, and its renewed found in the British use in urban forestry has been Isles, Italy or Spain, suggested. and very little is known about this species in western Europe. usmUlmus laevis Europeanlaevis white elmUlmus laevis EuropeanUlmus white elmUlmus laevisEuropean la

Genetic knowledge Threats to (Scolytus sp.) which are the vec- genetic diversity tors of the DED fungal agent (Ophiostoma novo-ulmi), which Ulmus laevis has not been div- Habitat destruction has caused prefer to feed on field elms in ided into sub-species and var- enormous damage to white elm western Europe and rarely visit ieties. More information is parti- populations, and continues to white elms. cularly needed about U. celtidea pose a major threat to the genet- - an endemic species occurring ic diversity of the species. Dra- in Russia, taxonomically very matic changes in the landscape close to the white elm. are occurring in riparian forests Studies using different along the banks of large rivers, molecular markers have revealed especially where land can be significant differences of white drained and reclaimed for agri- elm from the other two European culture or poplar cultivation. elm species, and also highlight- Consequently, white elm is now ed similarities with its North often restricted to fragmented American counterpart in the populations of a limited size, same section, the American facing the risk of genetic drift. white elm (U. americana L.). The impact of DED on white Chloroplast DNA studies of a elm populations is more serious large, West European sample in central and eastern Europe, identified the same haplotype in where infections and mortality 93 % of the trees, and only two are frequent, than at the western other types: a rare type in south- fringe of its natural range. This is west France, and another on the largely due to the bark beetles south eastern limit of the sampled zone. Isoenzyme studies carried out in Finland suggest that random genetic drift may have caused substantial differentiation among the small populations at the northern fringe of the natural range. aevisn white elmUlmus laevis EuropeanUlmus white elmUlmus laevisEuropean laevis white elmUlmus laev

Guidelines for genetic situ conservation units, such as conservation and use conservation seed orchards (in artificial conditions) or pseudo in Despite this pathological threat, situ conservation units (- the in situ conservation of white ations in original habitat), which elm genetic resources is still pos- brings together diverse material sible through the establishment from the same eco-region and of a network of conservation enhances genetic exchange, are stands. These stands should be highly recommended. White selected across the natural dis- elms can easily be propagated tribution range, incorporating by cuttings, and field clonal ecological variation, comprising archives can be maintained as at least 50 flowering trees in low hedges (1.5 – 2 m), which are each. In countries where the less attractive to the vectors of distribution of this species in DED. the wild is unknown, a pre- A European core collection liminary inventory should of elm clones has already be undertaken. Priority been established with should be given to margin- material from the nine al populations and rare countries participating floodplain communities in in the EU RESGEN danger of deforestation. project. It is important Silvicultural management that this collection is should stimulate and complemented with promote natural regener- material originating ation. However, planting from all the relevant of the original or local regions of Europe. material may be required when regen- eration is poor or the number of seed trees is insufficient. Complementary ex situ conservation measures must be undertaken when no legal habitat protection measure can be taken, when populations are small and fragmented, or when the impact of DED is too strong. In emergency cases, ‘static’ con- servation measures, such as clonal archives and cryo- preservation of seed lots can be applied. However, ‘dynamic’ ex UlmusEuropean white elmUlmus laevis Europeanlaevis white elmUlmus laevis EuropeanUlm whi

Distribution range of European white elm.

The Author wishes to acknowledge contribution from Dr. Lorenzo Mittempergher and CAB International Forestry Compendium CD-Rom (2003). for the 'Biology and ecology' and 'Importance and uses' para- graphs mushite elmUlmus laevisEuropean laevis white elmUlmus laevis EuropeanUlmus white elmUlmus laevis

EUFORGEN

These Technical Guidelines were Selected bibliography produced by members of the EUFORGEN Noble Hardwoods Network. The objective of the Net- Collin, E. 2002. Strategies and guidelines for the conservation of the genetic resources of Ulmus spp. Pp. 50-67 in Noble Hardwoods Network: Report work is to identify minimum genet- of the fourth and fifth meetings, September 1999 and May 2001 (J. Turok, ic conservation requirements in G. Eriksson, K. Russel and S. Borelli, compilers). International Plant Genet- the long term in Europe, in order ic Resources Institute, Rome, Italy. to reduce the overall conservation Mittempergher, L., A. Fagnani, and F. Ferrini. 1993. The White Elm: an interest- cost and to improve the quality of ing and ill-known elm [in Italian]. Monti e Boschi 44 (4): 13-17. standards in each country. Webber, J. 2000. Insect vector behavior and the evolution of Dutch elm dis- ease. Pp. 47-60 in The Elms: breeding, conservation and disease man- agement (C. P. Dunn, editor). Kluwer Academic Publishers, Boston, USA. Collin, E. 2003. EUFORGEN Tech- Whiteley R.E., Black-Samuelsson S., Jansson G. 2004. Within and between nical Guidelines for genetic con- population variation in adaptive traits in Ulmus laevis, the European white servation and use for European elm. (manuscript). white elm (Ulmus laevis). Interna- tional Plant Genetic Resources Institute, Rome, Italy. 6 pages.

Drawings: Ulmus laevis, Giovanna Bernetti. © IPGRI, 2003.

ISBN 92-9043-603-4

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