Vertical variation in stemflow generation.

Abstract

Stem flow production by a 15-yr-old Douglas fir tree was measured in the field, using artificial precipitation of 0.41-0.77 cm/hr, monitored at four points on the trunk below major whorls. Total stemflow was <2% of total precipitation. Some 98% of stemflow was produced in the upper half of the canopy vol., despite the fact that the sheltered, depressed branches of the lower canopy accounted for 31% of branch interception area.