Predicting earthworm biogeography and climate-driven shifts on China's Loess Plateau

Abstract

Earthworms are essential for soil health and ecosystem functions, yet their distribution and underlying mechanisms in arid and semiarid regions remain poorly understood. Here, we conducted a systematic field survey of 600 plots across 59 sites and employed a random forest model to map the earthworm distribution on the Loess Plateau and quantify potential changes under future climate scenarios. The resulting maps indicate that the total abundance and biomass of earthworms on the Loess Plateau are approximately 5.52 × 10¹² individuals and 1.88 × 10¹³ g, respectively. Regionally, the earthworm distribution decreases from southeast to northwest, driven by climate, whereas locally, soil, topography, and vegetation differences contribute to spatial heterogeneity. Under future climate scenarios, earthworm abundance is projected to increase by 44–61%, and earthworm biomass is projected to increase by 77–96% by the 2090s. Our results highlight the widespread distribution of earthworms in arid and semiarid regions and their potential expansion under global climate change, particularly in ecologically fragile areas.