Native earthworms maintain their environmental functionality following deforestation

Deforestation alters the abundance and diversity of key native soil organisms and may encourage the invasion of alien species. However, certain soil organisms (e.g., earthworms) can adapt to new land-use patterns following deforestation and continue to survive and thrive in the resulting new environments. It remains unknown whether the environmental functionalities of native soil fauna are influenced during their adaptation to land-use changes. The environmental impacts of earthworms are partially driven by their casts. For this study, we combined a field experiment with metagenomics and metabolomics to investigate the influences of deforestation (i.e., paired tea plantations vs. native forests) on fresh earthworm casts. It was found that the compositions of microbial communities in earthworm casts between tea plantations and forests were altered, as evidenced by Adonis analysis based on Bray-Curtis distance. In earthworm casts from tea plantations, the abundance of Thaumarchaeota increased by 152.6 % compared with forests, while those of Chloroflexi decreased by 32.9 %. Concurrently, some functions of earthworm were significantly upregulated to deal with environmental stress. For example, the nitrotoluene and xylene degradation functions of microbiota in earthworm casts were notably enhanced by 31.9 % and 14.8 %, respectively, in the tea plantations. Based on Adonis analysis, there were no significant differences between the functional compositions of bacterial communities and those of metabolites in the earthworm casts of tea plantations and forests. Our analysis revealed that, in response to long-term land -use modifications, microbiota and their associated metabolites in earthworm casts had the capacity to adapt to novel environments. Nevertheless, native earthworms still carried a significant imprint from their original habitats, which was critical for the preservation of environmental functionality. This knowledge is essential for elucidating the consequences of deforestation on the often neglected functionalities supported by native soil fauna as they adapt to land-use changes.