Succession of epigeic spider communities in substitute birch forests between 1988 and 1998.

We investigated spider fauna in 6 substitute birch stands in northern Bohemia between 1988 and 1998 in areas destroyed by air pollution. Spiders were caught using either pitfall traps or photoeclectors and each collecting method was evaluated separately. The comparison of results from year 1988 and year 1998 showed an increase in number of individuals but not in number of species. Although no clear trends were found when comparing the data by biodiversity indexes, two distinct clusters separating localities in 1988 and 1998 were found when comparing spider communities by Soerensen's index and cluster analysis. Based on these data we identified species mainly responsible for such changes. Our stud y shows that although biodiversity evaluated by biodiversity indexes and number of species was not changed during ten years of succession, progressive changes in the spider community occur in its structure at the level of single species.