Background Against the backdrop of worsening global climate change and frequent occurrences of extreme precipitation events, the issue of urban soil erosion has become increasingly prominent. Lawns serve as an important measure for managing urban soil erosion, and Trifolium repens, Lolium perenne, and Cynodon dactylon are typical high-quality grass species for soil and water conservation. However, it remains unclear how these three types of lawns perform in mitigating runoff and sediment under the condition of multiple rainstorms, and which one is more suitable for application in urban soil erosion control. Therefore, in order to explore the characteristics of soil erosion on sloping land covered by these three types of lawns under the condition of multiple rainstorms.
Methods For this study, three runoff plots were selected, each measuring 10 m in length, 2.5 m in width, with a slope of 13° and soil type mainly consisting of red soil and clay loam. Indoor artificial simulated rainfall was employed under the condition of 6 rainstorms (60 mm/h). ANOVA test was used to analyze the significance of differences, curve regression models were applied to obtain the optimal fitting effect for correlation analysis, and principal component analysis was adopted for comprehensive evaluation of soil and water conservation. The soil erosion characteristics of the three types of lawns and the lawn with the best soil and water conservation effect were thus derived.
Results 1) The runoff generation time in T. repens and C. dactylon grasslands showed a trend of first increasing and then decreasing, while no stable pattern was observed in L. perenne grasslands. Among them, C. dactylon grasslands exhibited the best effect in inhibiting and delaying runoff, followed by T. repens, with L. perenne performing relatively poorly. 2) Under 6 rainfall events, the total runoff yields of T. repens, L. perenne, and C. dactylon lawns were 133.02 L, 183.25 L, and 143.32 L, respectively, and the total sediment yields were 21.43 g, 9.38 g, and 5.89 g, respectively. The total runoff yield of T. repens was 7.19%–27.41% lower than that of C. dactylon and L. perenne, and the total sediment yield of C. dactylon was 37.38%–72.55% lower than that of L. perenne and T. repens. T. repens showed the best runoff reduction benefit, while C. dactylon had the best sediment reduction effect. 3) A significant power function relationship was found between runoff and sediment on the sloped land of the three lawn types, indicating a close quantitative correlation between these two key erosion indicators. Comprehensive evaluation, considering multiple factors, revealed that C. dactylon had the optimal soil and water conservation benefit.
Conclusions Comprehensive analysis indicates that herbaceous plants with multi-level horizontal leaves and stolon have a better inhibitory effect on soil erosion. Obviously, under the condition of multiple rainstorms, C. dactylon is the optimal choice for controlling soil erosion in urban lawns, followed by T. repens and L. perenne. This study can provide a reference for the selection of urban lawns, as well as for understanding the mechanisms of soil erosion and soil and water conservation in grasslands.
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