2019 Volume 32 Issue 3 Pages 138-147
Throughfall at an experimental Cryptomeria japonica stands in Nagasaka, Akita prefecture in a snowy region of Japan was measured using large bucket rain-snow gauges during the snow cover season from December 24, 2008 through March 17, 2009: 83 days. The canopy openness above the gauges was also calculated from hemispherical photographs. The order of canopy openness values (mean ± SD) from least open to most open was unthinned (15.1 % ± 6.5), thinned (34.3 % ± 8.2), and spur road (61.4 % ± 11.7). Multiple comparisons for canopy openness revealed significant differences among all combinations of the unthinned, thinned and spur road plots. During the season, the order of ratio of throughfall to gross precipitation from lowest to highest was unthinned plot (83.7 % ± 12.1), thinned plot (85.9 % ± 8.3), and spur road plot (89.6 % ± 5.8). Positive correlation was found between canopy openness and the ratio of throughfall to gross precipitation (r = 0.783, p < 0.001). Additionally, a significant logarithmic relation was found between canopy openness and the ratio of throughfall to gross precipitation (r = 0.884, p < 0.001). Winter precipitation during the season was categorized into solid and liquid precipitations based on the air temperature. The ratio of throughfall to gross precipitation tended to increase with the ratio of snowfall to gross precipitation.
