Model‐based impact analysis of climate change and land‐use intensification on trophic networks

There is well‐established evidence that land use is the main driver of terrestrial biodiversity loss. In contrast, the combined effects of land‐use and climate changes on food webs, particularly on terrestrial trophic networks, are understudied. In this study, we investigate the combined effects of climate change (temperature, precipitation) and land‐use intensification on food webs using a process‐based general mechanistic ecosystem model (‘MadingleyR'). We simulated the ecosystem dynamics of four regions in different climatic zones (Brazil, Namibia, Finland and France) according to trait‐based functional groups of species (ectothermic and endothermic herbivores, carnivores and omnivores). The simulation results were consistent across the selected regions, with land‐use intensification negatively affecting endotherms, whereas ectotherms were under increased pressure from rising temperatures. Land‐use intensification led to the downsizing of endotherms, and thus, to smaller organisms in the food web. In combination with climate change, land‐use intensification had the greatest effect on higher trophic levels, culminating in the extinction of endothermic carnivores in Namibia and Finland and endothermic omnivores in Namibia. Arid and tropical regions showed a slightly higher response of total biomass to climate change under a high‐emissions scenario with rising temperatures, whereas areas with low net primary productivity showed the most negative response to land‐use intensification. Our results suggest that 1) further land‐use intensification will significantly affect larger organisms and predators, leading to a major restructuring of global food webs. 2) Arid low‐productivity regions will experience significant changes in community composition due to global change. 3) Climate changes appear to have slightly greater effects in tropical and arid climates, whereas land‐use intensification tends to affect less productive environments. This paper shows how general ecosystem models deepen our understanding of multitrophic interactions and how climate change or land‐use drivers affect ecosystems in different biomes.