杜仲林下穿透雨时间及空间分布特征

通过对杜仲林下穿透雨的定位监测,结果表明:在测定期间,穿透雨量占总降雨量的72.5%,2004年7月的穿透雨量最大(319.9 mm),而穿透雨率最大值(85.5%)出现在2004年12月;在水平空间分布上,林下穿透雨显示出明显的空间变化,各观测点的穿透雨率具有显著性差异,而且穿透雨的空间变化率随着降雨量和降雨强度的增加而减小;杜仲林下穿透雨呈现明显的汇集效应,其中50%的观测点和28.8%的降雨出现了穿透雨率大于100%的情况;林冠特征影响穿透雨的空间分布,冠层的厚度和盖度与穿透雨之间均有显著的负相关性,但是穿透雨率与距主干的距离和分枝角度呈正相关.

Temporal and Spatial Distribution Patterns of Throughfall Under Eucommia ulmoides Forest

Throughfall under Eucommia ulmoides forest was measured from July 2004 to June 2005 at the Ecological Benefit Monitoring Station for Yangtze River Protection Forests.Over the whole measurement period,the volume of throughfall accounted for 72.5% of gross rainfall.Its maximum amount occurred in July 2004 and its maximum percentage relative to rainfall appeared in December 2004.Significant spatial variation in throughfall was observed below the canopy of E.ulmoides forest.The throughfall among different sampling sites differed significantly (p<0.05) and its CV decreased with the increase of rainfall amount and intensity.The throughfall under canopy had an evident effect as an influx,for the throughfall at 50% of the sampling sites and 28.8% of the total rainfall took on a throughfall percentage bigger than 100%.In addition,the canopy characteristics influenced the spatial distribution of throughfall.There was a significantly negative correlation among canopy height,coverage and throughfall percentage.However,there was a significantly positive correlation between the throughfall percentage,and the distance from the sampling site to the nearest tree trunk and the branches' angle inclination.