Multifaceted Patterns of Diversity and Co-Occurrence along an Extensive Survey of Shrubland Communities Across China

Interpreting biodiversity patterns and the underlying processes is crucial for evaluating the mechanisms of community assembly, but the view of multifaceted diversity patterns spanning broad spatial extents is less strengthened. We implemented an inventory of 1260 vegetation plots from shrublands across China with standardized methods and analyzed patterns of taxonomic and phylogenetic diversity with differential weighting of common and rare species, as well as phylogenetic co-occurrence structures. Taxonomic and phylogenetic diversity were linearly correlated when common and rare species were weighted equally, but had a logarithmic correlation when species were weighted with their relative abundances. While most shrubland communities were phylogenetically unstructured, the correlation between taxonomic and phylogenetic diversity covaried with phylogenetic relatedness when incorporating relative abundance, but only weakly so in phylogenetically over-dispersed communities. When we correlated patterns of taxonomic and phylogenetic diversity with different weightings for common versus rare species, we found an important role for geographic (e.g., longitude, altitude), climatic (temperature, precipitation) and soil factors. The importance of underlying variables varied between facets of diversity. We found a strong role for altitude in taxonomic, but less so for phylogenetic diversity. Furthermore, the importance of several environmental drivers varied depending on whether diversity metrics were strongly influenced by rare species or put more weight on common and/or dominant species. Overall, our assessment highlights the importance of synthetic analyses of patterns and processes of different facets of biodiversity to capture the full complexity of diversity in conservation studies.