Throughfall, stemflow and interception of rainwater in an evergreen broadleaved forest

Abstract In order to analyze the dyanmics of heavy metals in a forest ecosystem, throughfall and stemflow were collected for individual rain showers in an evergreen broad‐leaved forest dominated by Castanopsis cuspidata . The relation between throughfall (or stemflow) ( P x) and gross rainfall ( P ) was approximated by a linear regression equation P x= a(P‐b) . The values of coefficient “a” were 0.32–2.02 for throughfall at each sampling point and the mean values for 1976 and 1977–1978 were 0.682 and 0.767, respectively. The stemflow volume differed widely among individual trees, depending mainly on the tree form of each species. In particular, the tree form of Pasania edulis was found to be especially suited to collecting stemflow. One P. edulis tree collected 64% of the rainwater that fell onto its crown as stemflow. The ratio of stemflow to gross rainfall decreased in summer resulting from an increase in leaf biomass and an increase in air temperature. In fact, the values of coefficient “a” for mean stemflow per unit area were 0.180 for summer and 0.229 for other seasons in 1976, and 0.145 for summer and 0.155 for other seasons in 1977–1978 for different sampled trees.