Runoff and sediment effects in erosive rainfall of typical plant conservation practice in the upper reach of Guanting Reservoir, Beijing

To study the runoff and sediment reduction benefits from typical plant conservation practices in the upper reach of the Guanting Reservoir of northern Beijing, we selected five standard plots and analyzed the characteristics of erosive rainfall and plant diversity. Then the changes of runoff and sediment reduction benefits with precipitation, rainfall intensity and duration in different measures of typical plant preparation were studied, and the effects of different plant coverages on the runoff depth and the amount of sediment were evaluated, so as to explore the effective measure of plant conservation in the upper reach of the Guanting Reservoir. The results showed that: 1) the higher the grass coverage is, the better the runoff and sediment reduction benefits are, especially in torrential rains. The grassland with a coverage of 45%-60% can be effective for water and soil conservation plant measure, and this is recommended to be applied in Beijing mountainous areas. The combination of brush and high-coverage grass is proved to be rather effective in reducing runoff and sediment, and it is safer than sole grassland measure in the upper reach of Guanting Reservoir. 2) Reasonable vegetation configuration can strengthen the resistance to poor environment, and vegetation diversity is the key, which can increase plant coverage and maintain stability at certain level. When plant coverage is ensured, the higher the degree of diversity is, the slower the plant degeneration is, which can keep plant coverage and physiological activity normal, and reduce runoff and sediment. When designing plant conservation practice, diversity of plants should be concerned, diversity index, richness index and evenness index should be taken into account, and complementary-planting should be carried out year by year after the project finishing. Our study lays the foundation for comparison of runoff and sediment reduction benefits under varying measures, which could provide theoretical basis for the research of ecological security in Beijing mountainous area.