Determinants of Terrestrial and Limnic Species Richness in Germany

ABSTRACT Aim Biodiversity is increasingly threatened by human impacts. While abiotic conditions are well known to shape species richness, the role of human activities remains less clear. We examined how abiotic and human factors influence terrestrial and limnic species richness in a densely populated region with a long land‐use history. Location Germany. Time Period 1900–2023 (varies by taxonomic group). Major Taxa Studied Mammals, breeding birds, fishes, amphibians, reptiles, butterflies, dragonflies, fungi, vascular plants. Methods Species richness data were aggregated in 11 × 11 km grid cells and related to abiotic (climate, soil) and human drivers (land use, protection status). We applied a two‐step approach: (1) Boosted Regression Trees (BRTs) to select relevant predictor variables and (2) Generalised Additive Models (GAMs) to test their effects, accounting for spatial autocorrelation. Results Land‐use and climate were similarly important for species richness (26% vs. 21% in BRTs), while protection status and soil contributed less (8% and 9%). GAMs showed positive effects of temperature across many groups. Among land‐use factors, human footprint, urban open spaces and water bodies consistently enhanced richness. Protected areas were positively related to richness, whereas soil variables had mixed effects. Main Conclusions In Germany, species richness peaks not only in semi‐natural, protected areas but also along water bodies and within settlement open spaces. These results suggest that conservation strategies should integrate both traditional protected areas and human‐modified habitats that sustain high biodiversity.