Effects of deforestation on structure and diversity of small mammal communities in the Moravskoslezske Beskydy Mts (Czech Republic)

During 1970s and 1980s,, a large area,of mountains in, the Czech Republic was influenced by long-term industrial air pollution. Among the most degraded areas were the peaks of the Moravskoslezske Beskydy Mts, where vast clearings resulted from emissions and subsequent forest destruction. This study is, aimed at determining the degree of deforestation that is necessary to cause changes in structure and species diversity of small mammal communities that were observed previously. Communities of rodents and insectivores were monitored for a minimum of 3 years at two mountain ranges of the Moravskoslezske Beskydy Mts (Czech Republic) by standard mouse snap-traps. The localities (Smrk and Knchyne) differ by the degree of human disturbance. Clearings on Smrk Mt are very large (> 30 ha) with no remaining original forest growth as a result of intensive air pollution, unlike the same habitat type at Knchync Mt, where the clearings are minor (< 3 ha) and contain living solitary trees. Structure and diversity of small mammal communities in clearings were compared with those from original forests and other mountain habitats. Communities of small mammals at clearings in Smrk Mt (with dominating Microtus agrestis) are structurally very different from all other habitats, while structure of communities at Knchync clearings are very similar to those of original mountain forest (Complete linkage clustering based on Renkonen index). The community of the original mountain spruce forest at Knchync had the highest species diversity (according to Shannon-Weaver, Brillouin, and Simpson indices, Shannon evenness, and rarefaction), while species diversity at clearings of Smrk was the lowest. Shannon diversity of community-at Knchync primeval forest is similar to that of Knchync clearings, while at Smrk Mt the forest diversity is higher than that of clearings. The species diversity of mountain forest and clearings at Knchync Mt was significantly higher than that in the same habitats at Smrk Mt. Our results obtained in disturbed habitats at Knchync and Smrk Mts suggest that the degree of deforestation may influence the presence and/or the degree of community changes. If the forest destruction is relatively small (clearings < 3 ha), the structure and diversity of small mammal communities do not differ from those of original forest.