Amphibian distribution and assemblage structure were investigated along the last morphologically intact river corridor in Central Europe (Tagliamento). Thirteen taxa were identified with Rana latastei and Bufo bufo being the predominant species. In the main study reach, a 2 km 2 dynamic island-braided floodplain in the middle section of the river, 130 water bodies were delineated that were situated either in the active floodplain (82 sites) or in the adjacent riparian forest (48 sites). Results demonstrated that the active floodplain increased appreciably the available habitat for amphibians, despite frequent disturbances by floods or droughts. Amphibian richness within a given habitat was significantly correlated with distance from vegetated islands, fish density, and water temperature. In the active floodplain, species distribution was highly predictable, exhibiting nearly perfect nestedness, suggesting that selective colonisation and extinction processes predominated. The degree of nestedness was much higher than in the adjacent riparian forest or in regulated floodplains in Central Europe. Results clearly emphasise that amphibians can exploit the entire hydrodynamic gradient, except the main channel. In the active floodplain, vegetated islands and large woody debris are important, directly and indirectly, in maintaining both habitat and amphibian diversity and density in this gravel-bed river.

The effects of habitat restoration measures designated to promote farmland biodiversity have been documented at the field scale, but little is known about their role in restoring the agricultural mosaic. In this study, we analyzed the effects of wildflower strips (WFS) at the field scale and in the landscape context on butterflies in a Swiss arable landscape. Three hypotheses were tested: (1) butterfly diversity and abundance are higher in WFS than in conventional fields; (2) butterfly diversity and abundance are enhanced by the amount, proximity and connectivity of WFS in the landscape context; (3) additional factors influence butterfly diversity and abundance according to individual site conditions and landscape context characteristics linked to other landscape elements. WFS had more species and individuals of butterflies than conventional habitats. However, promoted species were mainly generalists; few specialists were enhanced. The diversity of all butterflies and of generalists increased linearly with percent cover of WFS, reflecting an effect of restoration measures depending on the landscape context. The influence of proximity and connectivity of WFS were, however, not significant. The occurrence of specialists was conditioned by plant species richness, while the effect of WFS for overall diversity was affected by the amount of grassland in the surroundings. We conclude that to increase the effectiveness of biodiversity-orientated restoration measures, their implementation should be steered toward increasing the share of WFS in the landscape. However, the combination of WFS with additional restoration measures might be needed to halt the decline of specialist species.

Amphibian distribution and assemblage structure were investigated along the last morphologically intact river corridor in Central Europe (Tagliamento). Thirteen taxa were identified with Rana latastei and Bufo bufo being the predominant species. In the main study reach, a 2 km 2 dynamic island-braided floodplain in the middle section of the river, 130 water bodies were delineated that were situated either in the active floodplain (82 sites) or in the adjacent riparian forest (48 sites). Results demonstrated that the active floodplain increased appreciably the available habitat for amphibians, despite frequent disturbances by floods or droughts. Amphibian richness within a given habitat was significantly correlated with distance from vegetated islands, fish density, and water temperature. In the active floodplain, species distribution was highly predictable, exhibiting nearly perfect nestedness, suggesting that selective colonisation and extinction processes predominated. The degree of nestedness was much higher than in the adjacent riparian forest or in regulated floodplains in Central Europe. Results clearly emphasise that amphibians can exploit the entire hydrodynamic gradient, except the main channel. In the active floodplain, vegetated islands and large woody debris are important, directly and indirectly, in maintaining both habitat and amphibian diversity and density in this gravel-bed river.

No abstract