Comparative Biome-Level Diversity Patterns

Abstract

Biomes -- the Earth's major terrestrial ecosystem types defined by characteristic vegetation physiognomy and climate regime (tropical forest; savannah; temperate grassland; boreal forest; tundra; desert; Mediterranean; tropical montane) - represent the primary spatial units for understanding global patterns of species diversity, ecosystem function, and biodiversity conservation priority at the largest scales. Yet comparative analyses of diversity patterns across all biomes simultaneously -- using standardised sampling designs and concurrent measurements of species richness, functional diversity, phylogenetic diversity, ecosystem multifunctionality, and climate sensitivity -- have been rare due to the logistical challenge of assembling globally representative datasets. This study integrates data from 247 standardised sampling sites across 18 biomes in 84 countries, measuring all four biodiversity dimensions simultaneously (species richness; FRic; PD; EMF) alongside climate sensitivity indicators (thermal niche breadth; phenological advancement rate; range shift velocity). Tropical forests showed the highest species richness (1,247 +- 384 species per ha; all groups combined) and highest EMF (0.84 +- 0.08) -- confirming their status as the global biodiversity and multifunctionality capital. Arctic tundra showed the lowest absolute diversity but highest climate sensitivity (range shift velocity 74.7 m/decade upslope; phenological advancement 6.4 days/decade) -- identifying it as the biome most rapidly transforming under climate change. A Biome Diversity Profile (BDP) integrating all four biodiversity dimensions reveals that no single biome leads on all dimensions simultaneously -- justifying the multi-dimensional conservation approach that accounts for the full spectrum of biodiversity value across biomes rather than focusing solely on species richness hotspots