Influence of the environmental factors on the species composition of lichen Scots pine forests as a guide to maintain the community (Bory Tucholskie National Park, Poland)

Abstract

Central European lichen Scots pine forests occur in extremely dry and poor sandy areas. This forest type, in terms of phytosociological classification, corresponds to the Cladonio-Pinetum association. This community is protected by European Union’s legislation (Natura 2000 habitat, code 91T0) and needs active protection to be maintained. The presented study was planned based on the conservation activities performed in 2017, which included thinning of the tree stand in selected areas of the lichen Scots pine forest community in the Bory Tucholskie National Park. Thinning effect was documented by the LiDAR (Light Detection and Ranging) data collected in 2017 before thinning and 2018 after thinning. Next we characterized two different forms of Cladonio-Pinetum association (lichen-rich and bryophyte-rich forms) and their relation to local environmental factors. To demonstrate that thinning is beneficial to the lichens we also compared the microclimatic conditions (temperature, humidity and light intensity) in thinned and unthinned areas. Vegetation and organic matter sampling was conducted in 2018 in the 24 sampling plots, each of 100 m2. Microclimatic measurements was done in 2018–2019 in one sampling plots of the thinned area and one additional control plot in the unthinned area. Sampling plots representing lichen-rich community had significantly lower canopy cover, higher number of lichen species, higher lichen cover and lower bryophyte cover in comparison to bryophyte-rich plots. The results showed that the lower canopy cover creates more favorable conditions for the occurrence of lichens, because of increasing the daily amplitudes of temperature, humidity and light intensity. Reduction of the canopy cover may be the easiest method to maintain the lichen pine forests community with high abundance of lichens in the field layer. This is particularly important in relation to the observed disappearance phenomenon of lichen pine forest in Europe. Due to this tendency, it is particularly important to actively protect these plant communities.