Data from: Reducing soil erosion by improving community functional diversity in semi-arid grasslands

1. Great efforts have been made to control soil erosion by restoring plant communities in degraded ecosystems world-wide. However, soil erosion has not been substantially reduced mainly because current restoration strategies lead to large areas of mono-specific vegetation, which are inefficient in reducing soil erosion because of their simple canopy and root structure. Therefore, an advanced understanding of how community functional composition affects soil erosion processes, as well as an improved restoration scheme to reduce soil erosion, is urgently needed. 2. We investigated the effect of community functional composition on soil erosion in restored semi-arid grasslands on the Loess Plateau of China. Community functional composition of 16 restored grasslands was quantified by community-weighted mean (CWM) and functional diversity (FD) trait values, which were calculated from nine plant functional traits of thirteen locally dominant plant species. Species richness and evenness were also measured. Soil erosion rates were measured using standard erosion plots. The multimodel inference approach was used to estimate the direction and the relative importance of these biodiversity indices in reducing soil erosion. 3. A robust and strong negative effect of functional divergence (FDiv) on soil erosion was found. The prevalence of particular trait combinations can also decrease soil erosion. The greatest control over soil erosion was exerted when the community mean root diameter was small and the root tensile strength was great. 4. Synthesis and applications: These findings imply that community functional diversity plays an important role in reducing soil erosion in semi-arid restored grasslands. This means that current restoration strategies can be greatly improved by incorporating community functional diversity into restoration design. We propose a trait-based restoration framework for reducing soil erosion, termed ‘SSM’ (Screening–Simulating–Maintaining). SSM aims to translate the target of community functional diversity into community assemblages that can be manipulated by practitioners. Based on this framework, a comprehensive procedure, highlighting functional diversity as the primary concern in determining optimal community assemblages, was developed to meet the pressing need for more effective restoration strategies to reduce soil erosion.

1. 全球范围内，科研人员已通过恢复退化生态系统中的植物群落开展水土流失治理工作，但水土流失并未得到大幅遏制。究其核心原因，当前的修复策略多形成大面积单优植被群落，这类群落因冠层与根系结构单一，抑蚀效能低下。因此，学界亟需深入解析群落功能组成对水土流失过程的调控机制，并优化水土流失防控修复方案。
2. 本研究以中国黄土高原半干旱恢复草原为研究对象，探究群落功能组成对土壤侵蚀的调控效应。研究选取16个恢复草原样地，基于13种本地优势植物的9个植物功能性状，通过群落加权平均性状值（community-weighted mean, CWM）与功能多样性（functional diversity, FD）量化群落功能组成，同时测定物种丰富度与均匀度；采用标准径流小区法测定土壤侵蚀速率，并通过多模型推断方法评估各生物多样性指标在降低水土流失中的作用方向与相对重要性。
3. 研究结果显示，功能分异度（functional divergence, FDiv）对土壤侵蚀具有显著且极强的负调控作用；特定性状组合的优势也可有效降低水土流失。当群落平均根径较小、根系抗拉强度较高时，其对土壤侵蚀的防控效果达到最佳。
4. 综合与应用：本研究结果表明，群落功能多样性在半干旱恢复草原的水土流失防控中发挥关键作用。这意味着，在修复设计中纳入群落功能多样性考量，可大幅优化现有修复策略。据此，我们提出一种基于性状的水土流失防控修复框架，命名为“SSM（筛选-模拟-维持）”，该框架旨在将群落功能多样性目标转化为可被修复从业者实操调控的群落组装方案。基于此框架，我们进一步构建了一套以功能多样性为核心筛选最优群落组装的标准化流程，以满足当前对更高效水土流失防控修复策略的迫切需求。