基于群落功能参数理解黄土区草地植物对土壤侵蚀的影响机制

Understanding the mechanisms for the effects of plants on soil erosion in the grasslands, is a hot issue in the field of soil erosion research, and will guide and improve the future practice of ecological restoration in the regions that suffer serious soil erosion (such as the Loess Plateau). The controls of plant community on soil erosion are the integration of the effects of different species, and this integration depends on abundances of constitutive species and their erosion-reducing traits. If we sum the information of species abundances and traits into a single index, this index will facilitate our understanding of the relationship between soil erosion and plants. The proposal of community functional parameter (CFP) provides us an approach to construct the index embracing species abundances and traits. However, the performance of CFP to predict soil erosion is not tested. In a small watershed of the Loess Plateau, we will monitor the soil erosion in the field plots in different plant communities, investigate the composition and structure of plant communities, measure the erosion-reducing traits of root and leaf, and calculate the CFPs using different traits. Then, we will establish the models that quantify the relationships between soil sediment yield and different factors (including CFPs and other indicators, for example, community cover and biomass, root density and root length density). By doing this, we can test the performance of CFPs calculated using different traits in predicting soil sediment yield compared with other indicators. If the CFP could predict soil erosion well, it will be a new approach to scale from plant organs to plant community, and will provide a new perspective to investigate the mechanisms for the effects of plants on soil erosion.

理解草地植物对土壤侵蚀的影响及其机制，是土壤侵蚀研究领域重要的科学问题，对于改善未来土壤侵蚀严重地区植被恢复的实践具有重要的指导意义。植物群落对土壤侵蚀的抑制本质上是群落中不同物种共同作用的结果，而这些作用的发挥取决于组成物种的多度及其抗侵蚀性状。如何有效地将物种的多度和性状值综合为一个指标，对于认识土壤侵蚀与植物的关系具有重要的意义。群落功能参数的提出，为此项问题的解决提供了一个研究思路。鉴于群落功能参数在预测土壤侵蚀方面的表现目前尚未得到检验，本研究在黄土高原小流域，通过径流小区监测、植物群落调查、植物根系和叶片抗侵蚀性状测定、以及群落功能参数计算，比较不同性状计算的群落功能参数与其他因子（例如，群落生物量、根系密度等）预测土壤产沙量的表现，检验群落功能参数是否是实现从植物器官到植物群落的尺度上推，并有效预测土壤产沙量的方法，以期为研究植物对土壤侵蚀的影响机制提供新的思路。

理解草地植物对土壤侵蚀的影响及其机制，是土壤侵蚀研究领域重要的科学问题，对于改善未来土壤侵蚀严重地区植被恢复的实践具有重要的指导意义。植物群落对土壤侵蚀的抑制本质上是群落中不同物种共同作用的结果，而这些作用的发挥取决于组成物种的多度及其抗侵蚀性状。本研究在黄土高原小流域，通过径流小区监测、植物群落调查、植物根系和叶片抗侵蚀性状测定、以及群落功能参数计算，利用网络分析研究了植物根系和其他性状之间的相互关系，利用第四角分析研究了植物性状和植物多度的交互作用对抑制土壤侵蚀的作用，比较了不同性状计算的群落功能参数与其他因子预测土壤产沙量的表现。发现，根系抗拉强度和根系质量分数与其他植物性状之间没有明显的相关关系，并各自形成独立的功能维度，而根系侧向分布和深度、植物高度另外一个功能维度；植物盖度和表征植物个体大小的性状（植物高度、根系侧向分布和深度）的交互作用会抑制土壤侵蚀；利用根系直径计算的群落功能参数与土壤侵蚀速率正相关，而利用根系抗拉强度计算的群落功能参数与土壤侵蚀速率负相关。以上结果表明，综合考虑植物多度和性状的交互作用，可以进一步深化土壤侵蚀的研究；群落功能参数是实现从植物器官到植物群落的尺度上推，并有效预测土壤产沙量的方法，在今后的研究中应该被重视。