Stand structure and species composition in the ‘Czmoń’ nature reserve

The ‘Czmoń’ nature reserve was established in 1998 to protect oak-hornbeam forest (Galio sylvatici-Carpinetum betuli) – a plant community rare in the Wielkopolska region. The reserve covers the area of 23.65 ha of forest in which also other plant communities rare in this region are found (Querco-Ulmetum minoris and Fraxino-Alnetum). Both communities of natural character, as well as degenerated communities, can be found in this reserve. This can be attributed to the type of forest management conducted in this area earlier. The objective of this study was to characterise the stand structure and species composition in this reserve and to trace potential changes in stands resulting from the abandonment of treatments associated with forest management. On potential forest sites of oak-hornbeam forest, elm-oak riparian forest and ash-alder riparian forest, forest communities at different stages of development and forms of degeneration are found to occur. On the basis of the species composition analysis of the undergrowth layer, the quantity of dead trees and shrubs, as well as the DBH distribution of living trees, we found an advancing process of regeneration in the direction of communities complying with potential vegetation. The highest proportion of dead trees was determined among those tree species growing in the reserve which were site (Pinus sylvestris) or geographically (Populus canadensis, Fagus sylvatica) alien for this particular area. In the undergrowth layer, a domination of oak-hornbeam forest and riparian forest tree species (primarily Carpinus betulus and Acer pseudoplatanus) was recorded. Absence of pedunculate oak (Quercus robur), as well as massive dying out of ash (Fraxinus excelsior) occurring in the undergrowth layer is perplexing