Environmental heterogeneity as a driver of terrestrial biodiversity on a global scale

To improve the effectiveness of biodiversity conservation and risk assessments under global changes, it is necessary to understand the drivers of terrestrial biodiversity on a global scale. Environmental heterogeneity is an important umbrella term for different environmental factors that contribute to species diversity. Previous studies have shown that there are significant relationships between geodiversity and biodiversity on a global scale, and that heterogeneity in geodiversity features and environmental variables, that is indicators of environmental heterogeneity (EH), drive biodiversity at local and regional scales. However, we do not yet know how terrestrial biodiversity is maintained, how well represented are the different taxa, and where would they be more at risks considering their abundances and diversities. In this study, we quantified EH of climate, topography, and land cover. We used four theoretical indexes (i.e., Fisher’s alpha, Shannon’s H, Hurlbert’s PIE, and Good’s u) to quantify terrestrial biodiversity based on abundance and diversity. We used regression models to explore the relationships between environmental heterogeneity and terrestrial biodiversity across different organismic groups (ants, bats, birds, butterflies, frogs, ground beetles, mosquitoes, odonates, orthopterans, rodents, scarab beetles, and trees) globally. We found significant relationships between environmental heterogeneity and terrestrial biodiversity, particularly for trees across the three EH components (climate, topography, and land cover), however, the effects of environmental heterogeneity on terrestrial biodiversity may vary among different groups of organisms. Land cover EH could affect the terrestrial biodiversity for ants, bats, birds, butterflies, frogs, mosquitoes, odonates, orthopterans, rodents, and scarab beetles. Furthermore, there were significant relationships between topographic EH and the terrestrial biodiversity for bats, butterflies, ground beetles, odonates, and trees. Climatic EH had significant effects on the terrestrial biodiversity for all organism groups. Our study provides new insights into biodiversity conservation by considering the terrestrial biodiversity based on EH, an indicator of geodiversity.