Functional traits explain seasonal variation effects of plant communities on soil erosion in semiarid grasslands in the Loess Plateau of China

Abstract Improved understanding of the impact of vegetation on soil erosion is critical for identifying effective strategies to use in soil and water conservation. Recently, although the concept of functional identity and diversity has been applied extensively in ecology, few studies have attempted to explore the effects of functional identity and diversity on soil erosion. In this study, the plant functional traits in different periods of a season were measured, and soil erosion was monitored in runoff plots of different types of plant community in the field under actual rain events. The measured plant functional traits were extrapolated to functional identity and diversity on the plant community scale. The impacts of functional identity and diversity on soil erosion in different periods of a season and with different rainfall intensity conditions were analyzed. The results showed that in the early and middle season, functional richness and functional evenness of the plant community play an important role in reducing soil erosion during low rainfall intensity. Plant tensile strength has a great effect on soil erosion at intermediate and high rainfall intensity in the early season. However, at the intermediate and high rainfall intensity in the middle season, plant aboveground parts has the greatest effect on soil erosion. At the end of the growing season, functional divergence is the largest determinant of soil erosion form low to high rainfall intensity. This work can provide insight into the mechanism of soil erosion and provide a valuable reference for plants used in soil and water conservation.