2003 Volume 16 Issue 6 Pages 605-617
The characteristics of throughfall of two forest stands with contrastive canopy structures were evaluated. Gross precipitation partitioning into throughfall in the experimental plantation stand of Cryptomeria japonica (ever-green coniferous tree) and that of Lithocarpus edulis (ever-green broad leaved tree) are studied. In order to compensate the effect of spatial variability of throughfall on the forest floor, the data of 3 tipping bucket raingauges were calibrated by the data of 25 or 30 fixed position funnel type raingauges. Spatial variability of throughfall in the C. japonica stand was larger than that in the L. edulis stand. The average ratio of throughfall to gross precipitation of C. japonica stand (0.64) was larger than the ratio of L. edulis (0.37) . In the L. edulis stand, throughfall started after only 0.9∼1.6mm of rain fallen, but it started after 1.9∼4.0mm of rain fallen in the C. japonica stand. These results suggested that LAI and canopy openness cannot fully explain the characteristics of throughfall and additional information, e.g. canopy structure (morphological factors), are needed.
