Is the plant species composition of Silver fir mixed forest in the Polish highlands affected by air pollution and climate warming?
Świerkosz, Krzysztof; Reczyńska, Kamila; Pech, Paweł
The changes in species composition of two isolated stands of Silver fir mixed forest (ass. Abietetum albae, syn. Abietetum polonicum) on the north-western border of its range in Poland were investigated, based on published data from 1966, 1995 and the authors' relevés made in 2011–2012. Transformation of vegetation was assessed using relative changes in species density and ordinations (PCA). Environmental conditions were specified using Ellenberg indicator values (EIVs) due to the lack of direct measurements from the past. The Zelený-Schaffers permutation test was used to assess correlation of EIVs with the sample scores of the PCA main axes. Results of the analyses suggest that among the ecological factors causing modifications in species composition were the changes in soil reaction and increase in temperature that occurred between 1961 and 2012. The gradual transition of Silver fir mixed forest in the Polish highlands from mesophilous to acidophilous forest is noticeable, both within investigated areas and the main range of this association in the country. The most likely reasons for this transition may be acidification caused by air pollution and climate change.