Even short-term revegetation complicates soil food webs and strengthens their links with ecosystem functions.
Degradation of dryland ecosystems is a worldwide problem caused by climate change and human activities. To restore these degraded ecosystems, governments have implemented projects that often include revegetation, but we still lack an understanding of how soil food webs and ecosystem functions are affected by revegetation. By conducting a large-scale revegetation experiment under two degradation intensities (low and high) on the Inner Mongolian degraded grassland, we tested the effects of revegetation on primary producers (plants), key components of soil food webs (bacteria, fungi and nematodes) and ecosystem functions (soil C and N mineralization). After 4 years, revegetation greatly increased the biomass of plants and soil bacteria and fungi but had less effects on soil nematode functional groups. Revegetation increased vegetation and bacterial diversity and soil C and N mineralization rates, altered the structures of vegetation and soil microbial communities, but did not affect soil fungal or nematode diversity. The stronger effects of revegetation on plants, soil bacteria, soil fungi and soil nematodes in plots with low degradation intensity than in plots with high degradation intensity indicated that future revegetation efforts should consider the degree of degradation. Revegetation also increased the interactions among plants, soil food webs and ecosystem functions, indicating that the revegetation-induced changes in soil food webs could facilitate the recovery of soil nutrients and vegetation productivity in degraded grasslands. Synthesis and applications. The effects of revegetation were stronger on plants (primary producers) and soil micro-organisms (intermediate trophic levels) than on soil nematodes (higher trophic levels), and even short-term revegetation increased the complexity of soil food webs and strengthened their relationships with soil functions in degraded grasslands. These results highlight the effects of restoration on multiple trophic levels in degraded drylands, and suggest that some aspects of plant-soil interactions in global drylands could be rapidly improved by appropriate restoration.