Acta Scientiarum Polonorum
Silvarum Colendarum Ratio et Industria Lignaria

Like in other parts of Europe, also in Poland three species of elm (Ulmus glabra, U. laevis, and U. minor) have been destroyed by Dutch elm disease (DED) - a fungal disease that appeared at the beginning of the last century. It is widely believed, that this fact is associated with a significant reduction in the number of all elm trees.

To determine how strong this reduction is and to assess the state of elms resources, we conduct research in various parts of Poland since 2013. In this article we present data on the Baltic Natural Forest Region.

In order to determine the number of elm stands, their participation in the tree stands and the age structure - forest documentation was comprehensively analyzed. In order to determine the share of particular species, their habitat preferences and the degree of damage by DED - field research, included 158 localities was carried out.

The presented data show that all the 3 native elms still exist in the whole ranges of their distribution 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 comparison with the previously analyzed Wielkopolska-Pomeranian region, a significant increase of U. glabra localities was noted in the studied area, This elm very clearly prefers forest plots located on the slopes. In all area of Baltic Natural Forest Region the symptoms of DED was noted, but the mass dying was recorded only in the case of two localities: one of U. glabra and one of U. minor.