The succession characteristics of soil erosion during different vegetation succession stages in dry-hot river valley of Jinsha River, upper reaches of Yangtze River

摘要

Declining vegetation coverage caused by serious soil erosion in dry-hot river valley of the Jinsha River has resulted in a vicious cycle of environmental deterioration and aggravated soil erosion. In order to identify the relationship between vegetation succession and transformation of soil erosion, the methods of "space replacing time" and ~(137)Cs technique have been used to analyze community structure of vegetation and distribution characteristics of ~(137)Cs contents in the slopes and vegetation units of five succession stages, which included native grassland, shrub, sapling forest, half-mature forest and near mature forest in Jiangjiagou gully, Dongchuan city, Yunnan province. We found, during the course of succession, the number of species in communities increased with vegetation development and succession, but the ~(137)Cs loss decreased with vegetation succession. Following the succession, near mature forest had the highest 137 Cs inventory and native grassland had the lowest ~(137)Cs inventory in both slopes and vegetation units. Principal component analysis showed that ~(137)Cs inventory was significantly positively correlated with average crown diameter of tree (ACDT), species number, tree coverage and average tree height. Average crown diameter of shrub (ACDS) and average shrub height were also positively related to ~(137)Cs inventory but to a lesser extent. Based on the results of our study, we illustrated the improvement of soil erosion control through soil conservation and water regulation with vegetation succession. Consequently, the results suggest that community features significantly affect soil erosion, through which we can evaluate and predict the soil erosion intensity of different vegetation.