Plant communities of alien broad-leaved species Fagus sylvatica, Quercus rubra and Juglans ailanthifolia in Latvia

In Latvia, the largest areas of introduced broad-leaved species are covered by Fagus sylvatica (44.0 ha), Quercus rubra (14.5 ha) and Juglans ailanthifolia (1.1 ha). Latvia is located in a transitional border zone between the broad-leaved forest and coniferous forest zones, on the northern limits of the nemoral biome. Therefore, an understanding of the diversity and stability of introduced broad-leaved plant communities and species is essential including analysis of soil properties, rgeneration potential, productivity and other parameters. To a great extent, broad-leaved stands predominantly composed by introduced species and their condition in latvia are an indicator of the stability of deciduous plant communities in the contemporary changing environment. In thus study, 49 plots were described in several selected sites. Additionally, soils and stand structure were studied. The relevés were classified and ordinate using multidimensional methods TWINSPAN and DCA. Following basal communities were distinguished: oligomesothropic Luzula pilosa-Fagus sylvatica community, mesoeuthropic Oxalis acetosella-Fagus sylvatica, Oxalis acetosella-Quercus rubra and Stellaria holostea-Juglans ailanthifolia communities, and euthropic Mercurialis perennis-Fagus sylvatica and Rubus caesius-Juglans ailanthifolia communities.