Pinus L. Species Richness in Europe: Distribution, Patterns, and Conservation Status

Unraveling large-scale species richness patterns and drivers is central to ecology. While climate, soil, topography, and human activities are widely recognized as key drivers, their relative contributions to Pinus L. diversity (especially in Europe) remain inconclusive due to scale dependence and methodological variations. This study integrates distribution data for 17 European Pinus species along with climatic, soil, topographic, and anthropogenic variables and employs Random Forest and Structural Equation Modeling to analyze spatial patterns of overall, wide-ranged, and narrow-ranged species richness, quantifying factor importance and driving pathways. Additionally, diversity hotspots were identified using the complementarity algorithm and top 5% richness methods. Results indicate higher species richness in topographically complex western Europe. Climatic seasonality emerges as the primary direct driver of overall and wide-ranged species richness. Human activities exert strong positive direct effects on all species groups and produce substantial indirect effects by altering the environment, with a relatively prominent influence on narrow-ranged species richness patterns. Although existing European Pinus hotspots are generally well-protected, conservation gaps in southwestern Europe necessitate targeted strategies. This study elucidates the regulatory mechanisms of Pinus species richness patterns across different distribution ranges, highlighting the need for differentiated conservation under ongoing climate change and anthropogenic pressures.