Reducing soil erosion by improving community functional diversity in semi‐arid grasslands

Abstract

Summary1. 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.

The effect of Robinia pseudoacacia afforestation on soil and vegetation properties in the Loess Plateau (China): A chronosequence approach

“…So, Control plots and Robinia plots had different species composition, but Control plots of all ages had lower cover values but higher number of species than Robinia plots, mainly of herbaceous perennial species that contributed most to the soil resistance to erosion (Zhu et al, 2015), and also Control plots of the same age were more homogenous in composition than Robinia plots, accordingly with the values of b-diversity. These differences between Control and Robinia plots may be the consequence of the effects that R. pseudoacacia plantations have on micro-environmental conditions.…”

“…Later, in 1999, the Chinese government implemented the ''Grain for Green" policy (conversion of steep cultivated land to forest and grassland) to control soil erosion, and again R. pseudoacacia was widely used for this purpose with the result that more than 70,000 ha were afforested with this species from 1950 to 2005 in the hilly Loess Plateau (Guo et al, 2005). However, in the past years, several negative effects of R. pseudoacacia plantations on soil properties have been described, questioning its beneficial role (Jiang et al, 2013;Zhu et al, 2015).…”

Effects of plant diversity on soil erosion for different vegetation patterns

“…Different erosion processes and steps have different traits, which can be affected by different plant functional traits (Zhu et al, 2015). Soil erosion types are thus meaningful for studying the relationship between soil erosion and plant diversity or plant functional diversity.…”

Did streamflow or suspended sediment concentration changes reduce sediment load in the middle reaches of the Yellow River?

“…As noted by Zhu et al (2015), the restoration strategies led to large areas of mono-specific vegetation in P 2 , and streamflow had not been substantially conserved by revegetation. The use of a sediment-trapping dam is a long-standing approach to controlling sediment yields, and it contributed approximately 60-70% of sediment load reduction during P 2 across eroding gullies and smaller tributaries (Ran et al, 2000;Zhang et al, 1997;Zheng, 2006).…”

“…Plot experiments showed that soil and water were significantly reduced by 54% and 79% when the vegetation coverage by grasses was 20% and 40%, respectively (Cai et al, 1992;Zeng and Ma, 1990). As noted by Zhu et al (2015), the restoration strategy in the 2000s was improved by incorporating community functional diversity into the restoration design. It was noted that vegetation recovery in the Loess Plateau was the best in China and statistically significant in recent years (Lü et al, 2003).…”