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Land-use history impacts functional diversity across multiple trophic groups 

Le Provost et al., 2019

Land-use change is a major driver of biodiversity loss worldwide. Although biodiversity often shows a delayed response to land-use change, previous studies have typically focused on a narrow range of current landscape factors and have largely ignored the role of land-use history in shaping plant and animal communities and their functional characteristics. Here, we used a unique database of 220,000 land-use records to investigate how 20-y of land-use changes have affected functional diversity across multiple trophic groups (primary producers, mutualists, herbivores, invertebrate predators, and vertebrate predators) in 75 grassland fields with a broad range of land-use histories. The effects of land-use history on multitrophic trait diversity were as strong as other drivers known to impact biodiversity, e.g., grassland management and current landscape composition. The diversity of animal mobility and resource-acquisition traits was lower in landscapes where much of the land had been historically converted from grassland to crop. In contrast, functional biodiversity was higher in landscapes containing old permanent grasslands, most likely because they offer a stable and high-quality habitat refuge for species with low mobility and specialized feeding niches. Our study shows that grassland-to-crop conversion has long-lasting impacts on the functional biodiversity of agricultural ecosystems. Accordingly, land-use legacy effects must be considered in conservation programs aiming to protect agricultural biodiversity. In particular, the retention of permanent grassland sanctuaries within intensive landscapes may offset ecological debts.

Importance of the drivers of multitrait diversity, mobility trait diversity, resource-acquisition trait diversity, and body size trait diversity. Relative effects (% R²), resulting from a model averaging procedure, were calculated for each group of predictors (i.e., land-use history, current land use, and the species pool). All predictors were scaled to interpret parameter estimates on a comparable scale. Note that for mobility, resource-acquisition, and body size trait diversity, we focused on animal traits and excluded plant traits from the analyses. Results were consistent considering spatial scales ranging from 500 to 1500 m radii surrounding the sampled grasslands.

https://www.pnas.org/content/early/2020/01/01/1910023117 

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