Redistribution Effects of Tree Canopy of Larix principis-rupprechtii Plantation on Precipitation in the Upper Stream of Saihanba Area

From May to October of 2009,the Larix principis-rupprechtii plantation which was 32 years old was observed to study the rainfall and its redistribution by L.principis-rupprechtii through test plot in Saihanba area of Hebei.The results showed that the rainfall was 348.4 mm in observing period,the canopy interception,throughfall,stemflow of the forest were 79.68 mm,266.74 mm,and 1.98 mm respectively.The rates of canopy interception,throughfall,stemflow were 22.87%,76.56%,and 0.57% respectively.In the rainy month of July,the interception,throughfall and stemflow were greater,but the rate of canopy interception was smaller;In the dry month of Auguse to October,the rate of canopy interception was higher than throughfall rate and stemflow rate,the wind made a great impact on stemflow.The relationship between interception,throughfall and rainfal were power and linear functions.The relationship between interception rate,throughfall rate and rainfal were power and logarithmic functions.The relationship between stemflow,stemflow rate and rainfal were linear function.The influence of rainfall intensity was not obvious.