Background/Question/Methods Land use intensification can greatly reduce species richness and dramatically alter ecosystem functioning. Resilience to these and other environmental changes depends critically on response diversity within the ecosystem's biota/biotic communities. Here, we present the results of two distinct meta-analyses that explore how loss of biodiversity with agricultural intensification impact loss of functional diversity, and functional redundancy. First, we analyze changes in species richness and functional diversity (FD) at varying levels of agricultural land use intensity. We test hypotheses of FD responses to land use intensification in plant, bird, and mammal communities using trait data compiled for 1600+ species. To isolate changes in FD from changes in species richness we compare the FD of communities to the null expectations of FD values. Second, we explore how land use change, the main global driver of biodiversity loss, impacts the response diversity of plant communities along 18 land use intensity gradients from nine countries, representing five biomes and more than 3000 species. We first classify species into functional effect groups, using 12 traits that affect biogeochemical processes. We then quantify response diversity through multivariate dispersion in response trait space, using 12 traits that affect plant responses to disturbances.

Results/Conclusions For the study on the loss of functional diversity we found that in over one-quarter of the bird and mammal communities impacted by agriculture, declines in FD were steeper than predicted by declines in species number. In plant communities, changes in FD were indistinguishable from changes in species richness. Land use intensification can reduce the functional diversity of animal communities beyond changes in species richness alone, potentially imperilling provisioning of ecosystem services. For the meta-analysis on the relationship between land use and ecosystem resilience, we found that land use intensification reduced response diversity, suggesting the creation of novel environmental filters that limit response trait distributions. Land use intensification also reduced functional redundancy (the number of species per effect group). Underlying these general trends, the response diversity and functional redundancy of individual effect groups under land use intensification showed a range of distinct trajectories, including decreasing, increasing, and other patterns. Our results show that intensified management of ecosystems for resource extraction can increase their vulnerability to future disturbances in the long term. Identifying the factors influencing the response diversity of individual groups of species that contribute to specific provisioning, regulating and cultural ecosystem services should be an important direction for future research.