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. 摘要 1. 干旱生态系统退化是气候变化和人类活动造成的世界性问题。各国政府采取了一系列恢复措施，例如植被重建，以恢复这些退化的干旱生态系统。但是目前为止，有关植被重建如何影响土壤食物网及其生态系统功能的实验论证相对匮乏。 2. 本研究利用中国内蒙古自治区锡林郭勒盟乌拉盖管理区不同退化强度草地上建立的大型植被重建控制实验，研究了植被重建如何影响土壤食物网中关键生物组分(植物、微生物和线虫)以及生态系统功能(土壤碳和氮矿化)。 3. 植被重建四年后，我们发现植物、土壤细菌和真菌的生物量得到了明显恢复，但土壤线虫多度恢复较差。植被重建增加了植物和细菌多样性以及土壤碳和氮矿化速率，也改变了植物和土壤微生物群落的结构，但不影响土壤真菌或线虫的多样性。研究表明退化草地土壤食物网多样性的恢复滞后于土壤食