Research Into Soil Erosion Of Shrub Plant Communities In Moderate Desertification Mountain Areas Under Artificial Rainfall Conditions

Guizhou Province is located at the central area of southwest Karst region. A great deal of land resources loss and a large number of stony desertification are usually seen in the area. As humid subtropical weather controls Guizhou Province, the rainfall is very rich, and the distribution on rainfall space-time is not even. It is a main reason for limiting local sustainable development that the torrential rain frequently causes soil erosion and land productivity to drop. In present research soil erosion and element loss of shrub forest were dealt with in intermediate rock desertification area of Guizhou when different rainfall intensity was set up controlled by the field artificial simulation rainfall device. Moreover, Hood infiltration device was used to test the soil infiltration to explain soil erosion. The main conclusions are as follows:(1) Under five different rainfall intensities conditions, the runoff volume was gradually increased with the passage of time, then gradually declined at three different rock exposed rate plots. In the same rainfall intensity, the bare rock big difference between the rate of district, the runoff larger rocks exposed rate similar to that of the two district, the runoff similar to that.The runoff volume was very similar at the two plots that the rock exposed rate was similar and that was very different among plots that the rock exposed rate was different. Cumulative runoff volume increased gradually with the changes of time. Cumulative runoff volume at the plot rock exposed rate of which was 70% exceeded the cumulative runoff at the plots with shrub plants the rock exposed rate of which were 42% and 32%. If the rock exposed rate of plots was close, the cumulative runoff of them was also very similar. The change curve of runoff at three different rock exposed rate plots can be described by R=b₀+b₁+b₂t² and the correlation efficient R² (>0.93) is very significant (p<0.01).(2) With the increase in rainfall intensity, the beginning of sediment concentration is gradually increasing. In the same rainfall intensity, the concentration of sediment process is not stable, higher concentrations of sediment start later in the sediment concentration gradually reduce volatility. Overall, sediment concentration at the plots with 32% of the rock exposed rate is taller than the other plots. In the same rainfall intensity the sediment of plots with intermediate rock desertification began to increase, when it reached its peak it began to decline. With the increase of rainfall intensity, the sediment also increased. Cumulative sediment at three different rock exposed rate plots with intermediate rock desertification could be described by R =b₀ +b₁ + b₂t². Cumulative runoff and soil erosion at three different rock exposed rate plots were closely related and linear regression equation was y = ax + b.(3) Based on gray correlation analysis we identified the impact of the primary and secondary factors on surface runoff coefficient. The order of the grey association about vegetation parameters was followed by the series: shrub layer leaf area index> Plant height > shrub and herb layers of leaf area index > herb layer leaf area index.(4) The three tested soil infiltration model showed that Kostiakov equation, in most cases, fitter than Philip and Horton equation to describe the soil infiltration in intermediate rock desertification, for which the accuracy of prediction of soil infiltration is high.Cumulative infiltration decreased with the increasing soil moisture at three different rock exposed rate plots .Under different conditions of soil moisture water infiltration with Hood Determination and steady infiltration rate rise with the change of soil moisture reduction.(5) The same rain runoff loss of intensity in a relatively high nutrient content in the beginning, with the rainfall over the extension of nitrogen, potassium, and total nitrogen concentration did not change significantly. Runoff loss of nutrient solution did not clearly reflects the strong correlation with the rain, light rain - have high rainfall intensity akin to the loss of concentration. In the same rainfall intensity, as the rate of increase of bare rock, nutrient runoff loss of gradually increasing the cumulative loss of nutrient runoff and loss of accumulated runoff can be used between the linear equation y = ax + b said. That the cumulative loss of nutrient runoff with the cumulative loss of accumulated runoff volume increase. In other words, with the extension of rainfall, nutrition, the loss of loss of more land productivity has been declining, thus affecting plant growth.