Changes in the Species Composition of Elms (Ulmus spp.) in Poland

Abstract

In nearly 600 randomly selected forest stands including elms (Ulmus spp.), we conducted field research to identify them to species level and to find trees showing symptoms of Dutch elm disease (DED). The presented data show that all the 3 native elms (U. glabra, U. laevis, and U. minor) still exist in the whole ranges of their distribution in Poland reported earlier, but their role as forest-forming species has changed. In comparison to published data, the contribution of U. minor has markedly decreased, while an increased contribution was observed in the case of U. laevis, a species which in the past was predominantly located out of woodland and was rarely cultivated. In mountains, where the most frequent is U. glabra, the contribution of elms to forest stands is currently clearly lower than in the lowlands and uplands of Poland. The observed changes most probably result from Dutch elm disease. It cannot be excluded that the changes are at least partly linked with natural correction of forest stand composition modified earlier by human activity (silviculture). In all parts of Poland, trees with symptoms of Dutch elm disease are found, but large-scale decline (of a majority of elm trees) is observed only in about 1.5% of the directly investigated localities.

The Populations and Habitat Preferences of Three Elm Species in Conditions Prevailing on Plains of Poland

“…It is also considerably uniform in terms of elm resources and the roles of trees of individual species in the tree stands. This homogeneity is indicate ysis [14]. It is also considerably uniform in terms of elm resources and the roles and numbers of trees of individual species in the tree stands.…”

“…The data used in this paper come from a part of Poland located in four natural forest regions (III, IV, V, VI), i.e., large areas characterized by more or less uniform conditions for forest growth and forest production (Figure 1, Table 1). The above-mentioned natural forest regions are described in the publication referred to above [14]. The region of study was selected because of its relatively large area (220,406 km 2 ) and the quantity of data available for analysis, as well as its significant representativeness.…”

“…The Polish populations are much less diverse than the Spanish, Fst = 0.089 and Fst = 0.239, respectively [16,17]. In Poland, the wych elm is practically the only representative of the genus Ulmus at locations above 400 MASL [14].…”

“…This is why today we can see just 1% of what used to be elm-dominated flood plains. All of the three native elm species in Poland are susceptible to infection with DED pathogens, but they show different degrees of damage [4,9,[12][13][14].…”

“…For the last several years, we have been evaluating the elm resources in Poland. As a result of the work, the total number of elm localities has been determined (based on forest documentation) [12] and the number of individual species in forested areas has been estimated [14]. Nearly 800 localities have been directly described and characterized in various respects, including DED occurrence.…”