A preliminary observation for quantifying detached stemflow

Detached stemflow has been defined as rainwater that breaks away from the stemflow and falls around the trees as throughfall. Quantitative measurements of detached stemflow were taken for two sample broadleaf trees on the university campus. Zelkova, with smooth bark, has a tree structure that concentrates rainwater, producing a large amount of stemflow. A rainwater collection system installed around the trunk can capture large amounts of throughfall as detached stemflow. The detached stemflow amount had almost doubled in water height equivalent to throughfall at the tree stand. Therefore, some trees generate much throughfall in the forest near the trunk. In the case of the Katsura tree, however, the stemflow was low. The throughfall attributable to the detached stemflow was less than the average throughfall. This low stemflow generation was assumed to be due to the roughness of the Katsura bark. The rainwater which attaches to the trunk and branches breaks away easily. Presumably, the leaves near the trunk intercept raindrops and disperse the rainwater to the surroundings. The detached stemflow can constitute a large quantity. It can be expected to be related closely to the stemflow generation mechanism.