Mean indicator values suggest decreasing habitat quality in Swiss dry grasslands and are robust to relocation error

作者：Steffen Boch, Angéline Bedolla, Klaus Ecker, Ulrich Graf, Helen Küchler, Meinrad Küchler, Rolf Holderegger, Ariel Bergamini · 发表于：DORA WSL (Swiss Federal Institute for Forest, Snow and Landscape Research) · 年份：2019 · DOI：10.14471/2019.39.010 · 被引用次数：30 · 研究领域：Wildlife Ecology and Conservation、Ecology and Vegetation Dynamics Studies、Rangeland Management and Livestock Ecology

Resurveys of historical plots are important to study vegetation changes over time. However, there is a high potential of relocation error, as historical plots were usually not permanently marked, which might result in misleading interpretations of changes. Quasi-permanent plots can relatively well be relocated, because of available information on their position (e.g. GPS coordinates). This minimizes relocation error. Quasi-permanent plots have thus been suggested to be suitable for vegetation resur-veys. Land-use abandonment and intensification are the major drivers of habitat degradation and there-by cause biodiversity loss. To counteract the ongoing decline of biodiversity in Swiss grasslands, the dry grasslands of national importance, comprising a total of 3631 sites across Switzerland (0.5% of its total area) were legally protected in 2010. These grassland sites represent various vegetation types and cover a wide elevational gradient. From 1995 to 2006, several thousand quasi-permanent vegetation plots of 28 m 2 were surveyed in the nationally important dry grassland sites. For each plot, GPS coordi-nates and a metric measure of post-processed GPS inaccuracy were recorded. In a set of 384 sites, 538 of the historical plots were resurveyed between 2011 and 2017. We tested the effects of GPS inac-curacy and elevation on temporal changes of species richness, species turnover and mean ecological indicator values. Overall, mean indicator values for light and stress significan...