Distance to nature-A new biodiversity relevant environmental indicator set at the landscape level

The ongoing worldwide biodiversity crisis comes along with a growing demand for feasible environmental indicators to measure, evaluate and communicate anthropogenic influence on biodiversity. Those indicators can be useful tools for national and regional management and support decision making processes. We propose degree of naturalness (Nd), distance to natural habitat (Dn) and the composite index distance to nature (D2N) as a highly comprehensible environmental indicator set that can be used as surrogate for land use related anthropogenic influence on biodiversity. A high resolution naturalness map for Austria based on the best nationwide available land use data was produced and used to test and demonstrate the applicability of the indicator set. Spatially inclusive and comprehensive indicator maps were calculated for the entire country (83,872 km2). Exemplary indicator values for all 2359 municipalities and six altitudinal zones were calculated and evaluated. Indicator maps of Austria clearly delimitate regions with elevated anthropogenic pressure on biodiversity due to land use characteristics. A sensitivity analysis conducted to evaluate the effect of land use data with different spatial and thematic resolution on the indicators showed that Dn reacts sensitive to spatially more detailed information about natural and near natural habitats. By contrast Nd and D2N were robust regarding the spatial and thematic resolution of input data. The proposed indicators do not measure biodiversity or a part of it directly, but the degree of habitat changes caused by anthropogenic land use, therefore they can be used for analysis over wide geographic ranges including different bio-geographic or climatic zones, and different spatial scales.