Spatial pattern of the throughfall volume on a steep slope dominated by deciduous broad-leaved trees

Abstract:

Rainfall can be partitioned into throughfall, stemflow and interception loss via the forest canopy. The variability of throughfall has an important role in forest hydrology and biogeochemistry. Previous studies have usually considered the plot scale rainfall partitioned through the canopy, and have not focused on the variation at the whole slope scale. In this study, the effect of stand location on the pattern of rainfall partitioning on a steep slope dominated by deciduous and coniferous trees was evaluated, based on the observation of throughfall and stemflow from the bottom to the top of the slope.

In deciduous forest, the mean throughfall to precipitation rations on upper and lower slope were 79 and 88 %, respectively. The mean stemflow to precipitation ratios on the upper and lower slope were 8.7, 2.4%, respectively. The lower part of the slope had a significantly higher throughfall ratio, and a smaller stemflow compared to the upper part of the slope. In coniferous forest, throughfall, stemflow, interception rates were not significantly different between upper and lower slope. In deciduous forest, the stems and branches of lower slope trees extended in the direction of the valley side, unlike the upper slope trees. Canopy structure of deciduous trees was different between the upper and lower slopes, while canopy structure difference was smaller in coniferous forest. The results of this study suggest that stand location on a hillslope affects the canopy structure of the deciduous trees along the hillslope, and lead to differences in rainfall partitioning processes.