Environmental heterogeneity as a universal driver of species richness across taxa, biomes and spatial scales

• Published in: Ecology letters Vol. 17; no. 7; pp. 866 - 880
• Main Authors: Stein, Anke, Gerstner, Katharina, Kreft, Holger, Arita, Hector
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Science 01.07.2014; Blackwell Publishing Ltd; Blackwell
• Subjects: Animal and plant ecology; Animal behavior; Animal, plant and microbial ecology; Animals; Biodiversity; Biological and medical sciences; climate; Ecology; Ecosystem; ecosystems; Environment; Fundamental and applied biological sciences. Psychology; General aspects; Habitat diversity; habitat structure; habitats; Heterogeneity; land cover; landscapes; meta-analysis; meta-regression; Plants; plants (botany); Population Dynamics; robust variance estimation; soil; spatial scale; species diversity; Species richness; Taxa; topographical heterogeneity; topography; Vegetation; vegetation structure; habitat structure; Regression; meta-analysis; Environmental factor; Spatial scale; Habitat diversity; Variance; robust variance estimation; Metaanalysis; meta-regression; topographical heterogeneity; Species diversity; Heterogeneity; Biome; Topography; Habitat; Vegetation structure; Species richness; vegetation structure; species diversity; spatial scale
• ISSN: 1461-023X; 1461-0248; 1461-0248
• DOI: 10.1111/ele.12277

Environmental heterogeneity is regarded as one of the most important factors governing species richness gradients. An increase in available niche space, provision of refuges and opportunities for isolation and divergent adaptation are thought to enhance species coexistence, persistence and diversification. However, the extent and generality of positive heterogeneity–richness relationships are still debated. Apart from widespread evidence supporting positive relationships, negative and hump‐shaped relationships have also been reported. In a meta‐analysis of 1148 data points from 192 studies worldwide, we examine the strength and direction of the relationship between spatial environmental heterogeneity and species richness of terrestrial plants and animals. We find that separate effects of heterogeneity in land cover, vegetation, climate, soil and topography are significantly positive, with vegetation and topographic heterogeneity showing particularly strong associations with species richness. The use of equal‐area study units, spatial grain and spatial extent emerge as key factors influencing the strength of heterogeneity–richness relationships, highlighting the pervasive influence of spatial scale in heterogeneity–richness studies. We provide the first quantitative support for the generality of positive heterogeneity–richness relationships across heterogeneity components, habitat types, taxa and spatial scales from landscape to global extents, and identify specific needs for future comparative heterogeneity–richness research.