太岳山油松人工林生态系统降雨的第一次分配

１９９２～１９９３年生长季节在山西省太岳山林区观测研究了不同郁闭度油松人工林对降雨的第一次分配．结果表明：林冠对降雨的第一次分配与降雨量级密切相关，降雨量级越大，截留率越小，而茎流率和穿透水比率越大．郁闭度亦影响林冠对降雨的第一次分配，郁闭度越大，截留率和茎流率越大，穿透水比率越小，而且随着降雨量级的增大，郁闭度的影响减弱．降雨的第一次分配主要取决于各月降雨的时间格局．干旱季节林冠对降雨的截留率较大，穿透水比率和茎流率较小，郁闭度对降雨第一次分配的影响较大；而在雨季则相反．整个生长季节，３号实验地（郁闭度为０９）的林冠截留、茎流及穿透水分别占降雨量的１５９％，２１％和８２０％，０号实验地（郁闭度为０６）的相应比率为１３６％，１９％和８４５％．因此，在干旱地区或具有明显干旱季节的地区经营人工林，必须考虑林分的生产力选择适当的林分密度，适时疏伐，增加林下降雨，提高土壤含水量，从而促进林木生长

Study on the First Distribution of Precipitation by Pinus tabulaeformis Plantation in the Taiyue Forest Region

This paper discusses the first distribution of rainfall by two Pinus tabulaeformis plantations with different canopy densities in the Taiyue Forest Division of Shanxi province during the growing seasons from 1992 to 1993.It shows that the first distribution of precipitation by canopy is more relative to the rainfall class,the higher the rainfall class is,the less the interception is, and the more the stemflow and throughfall are. The first distribution is also influenced by canopy density,as the closer the forest is,the more the interception and stemflow are,and the less the throughfall is,and the effect of canopy density on which is weaker with the increasing of rainfall class. The first distribution in every month is mainly dependent on the pattern of rainfall:higher interception,lower throughfall and stemflow,lead to less influence of canopy density on it during dry season,while reversed during rain season.The interception,stemflow and throughfall of No.3 experiment site with the canopy density of 0.9 are respectively 15.9%,2.1% and 82.0% during the whole growing season,while these of No.0 experiment site with the canopy density of 0.6 are respectively 13.6%,1.9% and 84.5%.So the appropriate stand density should be selected to increase the rainfall under the canopy,to raise the soil moisture content and accelerate the growth of forest in the regions which are dry or have longer dry season.