Linking the diversity and structure of French avian communities with landscape parameters, climate and NPP flows

Increasing land use intensification (“LUI”) threatens ecosystem functioning by altering the flows of net primary production (“NPP”) and interacts with other drivers of change (landscape use, climate). According to the “species-energy” hypothesis, such alteration of NPP flows should affect biodiversity patterns. However, the capability of the human appropriation of NPP (“HANPP”) to drive species community patterns has received little evaluation so far. Using linear mixed-effects models, we assessed the efficiency of indicators related to HANPP, landscape and climate to explain the variability of seven biodiversity facets (i.e. species richness, mean trophic level, habitat specialization, functional richness, evenness, divergence and dispersion) calculated from 2286 avian communities from the French national monitoring survey of breeding birds. Whether indicators related to HANPP or landscape best explain biodiversity facets greatly vary from one biodiversity index to another, but the landscape characteristics were almost always the best predictors of avian communities over NPP flows or climate. Only functional evenness and mean trophic level were consistently explained by NPP flows and almost not by landscape parameters. Overall, climate (i.e. temperature and precipitation) was a weak predictor of biodiversity at this spatial scale. Most biodiversity facets exhibited a hump-shaped relationship with NPP flows, except for habitat specialization and functional divergence (U-shaped relationship). These findings imply that (i) the response of one facet cannot be a surrogate for the overall response of biodiversity, (ii) the choice of one indicator should be hypothesis-driven and (iii) account for its ability to detect the phenomenon at stake.