Tree mortality after wind disturbance differs among tree species more than among habitat types in a lowland forest in northeastern Poland

Tree mortality was studied in a 460-ha swath of managed lowland forest that was damaged by a windstorm in July 2002 and set aside for research purposes. The goal of our investigation was to answer three specific questions: (1) Were tree stands in some habitat types more affected by the wind than others? (2) Were some tree species more vulnerable to wind damage? (3) Have smaller trees survived the windstorm better than larger ones? Based on measurements in 111 regularly distributed sample plots, we found that tree mortality amounted to 49% of tree numbers and more than 48% of the basal area. Only two plots were not damaged, and in one sample plot, all trees had been broken or uprooted by the wind. Differences in tree mortality among three major habitat types, apparent in satellite images, were not statistically significant. Scots pine and silver birch displayed significantly higher mortality rates than other tree species, and black alder was least affected by the windstorm. Scots pines were the tallest trees in analysed forest, but statistical analysis employing the odds ratio revealed that these higher mortality rates were not associated with the height difference between the pines and other trees growing in their immediate vicinity. Species composition of the remaining stands was more complex than that prior to the windstorm. We concluded that although salvage logging and replanting with seedlings is the most reasonable option from the point of view of timber production, it is not necessary for saving the integrity of the forest ecosystem and maintaining the continuity of ecosystem services.