The correlation between soil moisture and grass growth in different slope positions of gully badlands in Dryhot Valley

Badlands are extremely developed due to gully erosion in Yuanmou dryhot valley of Jinsha River. Grass growth characteristics and soil moisture conditions in different slope positions of gully badlands were surveyed and analyzed. The results showed that there were significant differences (P0.05) for grass performance in different slope positions of gully badlands, especially, there were highly significant differences (P0.01) between the upper position and the middle or lower positions in the same slope. Both the grass coverage and aboveground biomass increased in the order of Upper Middle Lower. Under the same precipitation conditions, soil moisture in different slope positions declined in exponential trend with different rates over time which resulted in different soil water contents. The declined rates of soil moisture decreased in the order of Upper Middle Lower which brought different soil water contents in the reverse order in the same monitoring period. There were significant correlations between soil water content including average (P0.05) and final (P0.01) and grass coverage and aboveground biomass during the monitoring periods which indicated that the different soil water content under different slope positions were key factors to determine the grass growth in gully badlands.