High diversity of odonates in post-mining areas: Meta-analysis uncovers potential pitfalls associated with the formation and management of valuable habitats

A growing number of studies indicate high conservation potential of freshwater habitats occurring in post-mining areas. The overall diversity of these habitats depends on many factors, however, even a high diversity may diminish significantly over time. Therefore, it is difficult to identify and understand the importance of key habitat properties for diversity. Here I present analysis of three studies comparing the diversity of dragonflies and damselflies (Odonata). Each study was performed in different coal mining basins within the Czech Republic (a total of 94 sites). In this analysis, I used generalized linear mixed models and several multivariate methods to analyze the effects of a number of environmental characteristics such as depth, bottom substrate or bank slope, reflecting not only the current quality but also the succession and formation of individual pools. The occurrence of overall 14 nationally red listed species indicates the high conservation value of these habitats, while the 40 species found indicate that these areas contribute significantly to regional diversity. Species richness of individual pools was associated with habitat type (spoil heap vs. mine subsidence) and with several habitat variables, in particular the character of vegetation around aquatic habitats. In conclusion, the results indicate that diversity and species composition are significantly influenced by factors reflecting the formation and subsequent succession of pools. Effective conservation management should concentrate primarily on modifying pools' initial properties such as bottom substrate. Subsequent management should then sustain landscape dynamics, which means in particular to sustain minor disturbances that subsequently affect vegetation succession and prevent excessive overgrowing of expansive vegetation, as doing so is promoting the habitat heterogeneity which is essential to high biodiversity in these areas. (C) 2016 Elsevier B.V. All rights reserved.