Agriculture & Forestry, Vol. 58. Issue 3: 105-113, 2012, Podgorica 105 UDC (UDK) 630*2:582.635.1 Marina NONIĆ, Jovana DEVETAKOVIĆ, Mirjana ŠIJAČIĆ-NIKOLIĆ 1 , Jelena MILOVANOVIĆ 1 YIELD VARIABILITY AS A BASIS FOR CONSERVATION AND DIRECTED UTILIZATION OF EUROPEAN WHITE ELM (Ulmus effusa Willd.) GENE POOL AT GREAT WAR ISLAND ABSTRACT The European White Elm (Ulmus effusa Willd.) is a species that belongs to the group of noble broadleaves, characterized by exceptional features and wood quality. In the forests of Serbia, the European White Elm belongs to the category of rare and endangered species according to the IUCN categorization. The disappearance of wetland habitats is the primary threat to the survival of White Elm populations and to the genetic diversity of this species. Draining of wetland habitats for the needs of agriculture or cultivation of poplars leads to dramatic changes in ecosystems where the White Elm grows. As a result, fragmentation of White Elm populations into smaller populations, groups of trees and individual trees occurred, which will ultimately lead to genetic drift problems, and therefore, to the ecological instability of this species. The population of European White Elms in the territory of the Great War Island includes more than fifty trees which occur in three spatially isolated subpopulations. This paper presents results of the analysis of morphometric characteristics of fruits (width and length) and seeds (width, length, position and germination), showing significant variability within the population. On the basis of the obtained results, the conservation and directed utilization of White Elm genetic resources will be realized: in situ - by the selection of rare genotypes within the available gene pool and their inclusion into a network of habitat conservation and ex situ – by establishing progeny tests intended for further exploration of population genetic potentials, generative and clonal seed orchards and storing rare genotypes into the seed bank. Keywords: Great War Island, European White Elm, gene pool, yield, variability, conservation INTRODUCTION The European White Elm (Ulmus effusa Willd. 1787; Syn: U. pedunculata Foug. 1787, U. leavis Pallas 1784) belongs to the family Ulmaceae Mirb., which 1 Marina Nonić, (corresp. author: marina.nonic@sfb.bg.ac.rs), Jovana Devetaković, Mirjana Šijačić-Nikolić, Faculty of Forestry, University of Belgrade, Kneza Visešlava 1, Beograd, Srbija (Belgrade, Serbia); Jelena MILOVANOVIĆ, Faculty of Applied Ecology “Futura”, Singidunum University, Maršala Tolbuhina 13-15, Belgrade, Srbija (Serbia)