Human-induced land degradation and biodiversity of classical karst landscape: on the example of enclosed karst depressions (dolines).
In the karst landscape of the Kras Plateau (south-west Slovenia), we studied the impact of historical human-induced land degradation on biodiversity by studying the characteristics and changes in vegetation of degraded and nondegraded karst depressions (dolines). Intensive human-induced land degradation began as a consequence of the abandonment of traditional land use; thus, many dolines have disappeared by being completely filled with waste material and overgrowth. The study is based on a chronosequence approach and assesses whether vegetation (e.g., community succession stages) can be used as a (bio)indicator of land degradation to estimate approximately the duration of degradation on the basis of the stage of succession. The locations and duration of degradation of dolines were identified in advance by analysing a time series of historical aerial photographs, topographical maps, and digital elevation models. Ecological evaluation was based on sampling the floristic composition and the topsoil. In this study, three vegetation measures were established as indicative of degradation: (a) the appearance of ruderal species, (b) hemeroby, and (c) alien and invasive species. A succession model of degraded karst landscape was produced on the basis of identified chronosequences to assess the long-term spatial impact of doline degradation on karst biodiversity. The model is showing the tendency towards the vegetation homogenization of karst landscape.