Simulated climate change disrupts soil food webs and agroecosystem services in two contrasting Mediterranean drylands

Abstract

Climate change and intensive agriculture are major threats to soil biodiversity and key ecosystem functions, and Mediterranean systems are particularly vulnerable to these global change drivers. In such threatened environments, gaining insight into the interactions between aboveground and belowground agroecosystem components is essential for enhancing ecosystem resilience and long-term agricultural sustainability. Here, we evaluated the effects of experimental drought and warming on indicators of soil functioning, soil food web structure, and crop performance under varying management practices (i.e., inversion tillage vs. non-inversion chisel tillage) over three growing seasons in two rainfed cereal-legume systems in the southern and central Iberian Peninsula. Our results show that climate change reduced SOC and increased β-glucosidase enzymatic activity under reduced tillage and enhanced ammonium and nitrate accumulation under conventional tillage, while drought reduced nematode abundances and favored r-strategist bacterial feeders. Under reduced tillage, warming reduced plant-parasites and favored fungal feeders, revealing a bottom-up regulation of omnivore-predators by plant-parasites, whereas this regulation was suppressed by warming under conventional tillage. Drier and warmer conditions accelerated crop phenology by 10–15 days, impaired photosynthetic efficiency, and reduced crop yields up to 68%, without compromising grain quality. The interaction of multiple climate factors amplified detrimental effects on soil biodiversity and agroecosystem functioning. These results highlight the constraints of current climate-smart agricultural practices, underscoring the urgent need for climate action to ensure food security in drylands.