A Pinus tabulaeformis plantation in western Miyun Reservoir of Beijing city was observed and ana-lyzed to study canopy interception

throughfall

and stemflow.Results showed that the relationship between the amounts of canopy interception and precipitation was the power function

but the relationship among throughfall

stemflow and precipitation displayed a linear correlation.Contributions of canopy interception

throughfall

and stemflow to total flux of rainfall were 7.23%～87.39%

12.56%～91.58% and 0.007%～1.77%

respectively. The differences of environmental aspect

meteorological condition

and characteristics of rainfall were a major factor which caused the discrepancy of atmospheric precipitation chemistry in the same area.When the precipitation passed through the canopy

the content of chemical elements in through-fall and stemflow increased in comparision with that of the precipitation.There was a positive correlation be-tween the individual element content in throughfall and the interval of precipitation

but a negative correla-tion with rainfall intensity and its amount. The correlation between the phosphorus and potassium contents in stemflow and characteristics of precipitation was the same as throughfall except for nitrogen element.