Dominance of precipitation and its interactive effects with warming on epigeic arthropod communities in an alpine meadow

Arthropods play a vital role in litter decomposition, nutrient cycling and the regulation of microbial activity. Despite climate change-induced increases in temperature and precipitation anomalies, the interactive effects of these drivers on arthropod communities remain poorly understood. A three-year field experiment was conducted in an alpine meadow on the eastern edge of the Qinghai-Tibetan Plateau to examine the independent and interactive effects of altered precipitation and warming on epigeic arthropod communities. The full factorial experiment included nine treatments combining three precipitation levels (-50%, 0% and +50%) with three warming levels (+0, +1 and +2 °C). The results showed that the precipitation treatment significantly changed the taxonomic composition of the epigeic arthropod communities, with a significant increase in their richness and Shannon index along the precipitation gradient. Collembola were more sensitive to altered precipitation than mites. In contrast, warming alone had no significant effect on these communities, but it nonadditively interacted with precipitation on the arthropod abundance (mainly Collembola). Critically, 1 °C warming reversed the effect of increased precipitation, resulting in a significant increase of 105.25% in the arthropod abundance. These climate-induced alterations in the arthropod communities were primarily mediated by changes in the vegetation coverage, species richness, soil bulk density, water content and nutrients. Our findings highlight that it is interactive climate drivers, rather than factors in isolation, that govern these alpine ecosystems, cautioning against over-reliance on single-factor studies. Consequently, climate-induced changes in arthropod communities may cascade through the soil food web, influencing overall ecosystem functioning.