Improving Soil and Water Conservation of Riparian Vegetation Based on Landscape Leakiness and Optimal Vegetation Pattern

Soil erosion inflicts multiple and severe damage throughout the world. The importance of vegetation spatial patterns in conserving soil and water has been widely acknowledged. In this study, by using the leakiness index (LI), which indicates the soil and water conservation function of the landscape by integrating landscape patterns closely with hydrological processes, we analyzed the changes in this function of riparian vegetation under different patterns with the aim of identifying the optimal pattern for improving soil and water conservation in severely eroded riparian buffer zones. Prior to this, the relationship between the erosion modulus and LI was discussed to provide certain evidence for the potential application of LI to the study area given the limited empirical works. Results showed that LI illustrated a significantly linear correlation with the erosion modulus (R2 = 0.636, p < 0.01), thereby suggesting a promising application of LI in the Beijiang riparian vegetation buffer zone. A comparison of the LI values regarding four different vegetation patterns indicated that under the premise of the same coverage (40%), the aggregation degree and patch orientation with low LI values exerted improved performance for soil and water conservation, so we selected the horizontal distribution and compact aggregation as the optimal pattern for vegetation regulation. The spatial variations of LI values in the study area showed that five regions were suffering from severe erosion, thus becoming the targeted area for regulation. The final regulation with the optimal vegetation pattern in severely eroded areas performed well given that the soil and water conservation was improved to a high level with a LI value less than or equal to 0.2. The results described in this study provide an alternative screening method to figure out the severe erosion areas needing improvement, a further understanding of the effect of vegetation pattern on soil and water conservation and a theoretical basis for the extended application of LI