Responses of microarthropods and nematodes to long-term warming in alpine meadows are precipitation-dependent effects

Abstract

Global warming significantly impacts soil fauna in terrestrial ecosystems, yet the differential responses of various groups, such as surface-dwelling microarthropods, soil-dwelling microarthropods, and soil nematodes, remain poorly understood. To address this, a long-term warming experiment using open-top chambers (OTCs) was conducted in alpine meadows of the Qinghai-Tibetan Plateau. Ten years after OTC installation, surface-dwelling, soil-dwelling microarthropods and soil nematodes, plant communities, and soil properties were investigated in September in the normal precipitation year 2019 and in the wet year 2020. The results were that: (1) shifts in taxonomic composition were more pronounced in surface-dwelling microarthropods and soil nematodes than in soil-dwelling microarthropods; (2) warming increased nematode taxonomic richness and Shannon diversity but reduced nematode abundance and surface-dwelling arthropod richness in the normal year, while only nematode abundance increased in the wet year; (3) warming altered nematode trophic structure by decreasing the relative abundance of bacterivores and increasing that of plant-parasites; (4) soil moisture and temperature were the primary drivers of soil faunal community changes, with ammonium nitrogen also being an important factor for soil nematodes. Our results demonstrate that the soil nematodes exhibited the strongest response to warming, followed by surface-dwelling and soil-dwelling microarthropods, and the warming effects on soil fauna abundance and diversity were dependent on precipitation. These taxon-specific sensitivities highlight their utility as bioindicators for monitoring alpine ecosystems.