Habitat islands outside nature reserves - Threatened biodiversity hotspots of grassland specialist plant and arthropod species

In transformed landscapes, many populations of grassland specialist plant and animal species live outside the few protected areas and are often preserved on 'small natural features' (SNFs) such as road verges, field margins and rocky outcrops. In the steppe and forest steppe zones of Eurasia ancient burial mounds (kurgans) are widespread SNFs providing refuge for grassland species. Based on a large-scale botanical and zoological survey of 138 kurgans in Hungary, we compared the management regimes, the presence of threatening factors and the conservation potential of kurgans embedded in non-protected transformed landscapes and in protected areas. We found that kurgans extend the borders of the protected areas by maintaining populations of grassland specialist plants and arthropods (ants, orthopterans, true bugs and rove beetles) even in transformed landscapes. We revealed that the lack of proper management, the presence of anthropogenic disturbances and encroachment of woody species are the most considerable threats to the long-term maintenance of biodiversity on kurgans located outside the protected areas. For their effective conservation a new approach is needed, which can cope with the small area and dispersed localities of the kurgans and can integrate them into the network of other SNFs on a landscape-level. As the ecological importance of kurgans is disproportionate to their size conservation actions focusing on their protection offers a greater rate of return of the efforts than can be expected in case of larger continuous sites.