Climate-driven expansion and northwest migration of earthworm habitats on China’s Loess Plateau

Earthworms play a pivotal role in regulating terrestrial ecosystem services and functions. However, the regional distribution of suitable earthworm habitats and the key environmental drivers shaping this distribution remain underexplored, particularly in arid and semiarid areas. This study employed an optimized MaxEnt model to predict the suitable habitat distribution of earthworms on the Loess Plateau, integrating 116 earthworm distribution records from systematic field surveys with 21 environmental factors, and analyzed their responses to these factors. We further projected potential changes in earthworm habitat suitability under different future climate scenarios. Results indicate that 63.2 % of the Loess Plateau (39.7 × 104 km2) constitutes suitable habitats for earthworms. Soil properties emerged as the most critical drivers of habitat suitability, with pH, coarse fragment content, and total phosphorus content being the primary influences. Climatic factors, including the minimum temperature of the coldest month and precipitation of the wettest month, also significantly modulated habitat distribution. Under future climate scenarios, earthworm suitable habitats are expected to expand, primarily driven by the expansion of moderately and highly suitable zones. By the 2090 s, the total suitable area is expected to increase to 52.7–56.5 × 104 km2. Concurrently, the centroid of suitable habitats is predicted to migrate northwestward across all scenarios. The study enhances our understanding of earthworm distribution patterns in arid and semiarid ecosystems and provides a scientific basis for conserving earthworm diversity and optimizing their ecological functions in the Loess Plateau and similar regions.