北京土石山区4种典型林分的水文效应研究

Study of Hydrological Functions of Four Types of Forest Stands in Rocky and Earthy Area of Beijing

以北京土石山区4种典型林分的林冠层、枯落物层、土壤层3个水文作用层为研究对象,采用浸水法等传统测量方法,测定了不同林分的冠层截留量、树干径流量、穿透降雨量以及土壤和枯落物层的水力学参数,并分析了其水文效应。结果表明：不同林分的林冠截留能力相差较大,其中侧柏—黄栌混交林的冠层截留率最大为29.1%,其余依次为侧柏林、油松纯林和元宝枫纯林,油松纯林的树干径流量占降雨比例最大（5.8%）,其余依次为侧柏—黄栌混交林、元宝枫纯林和侧柏林,各项林冠截留率与大多数在干旱半干旱地区取得结果较为一致。从月份尺度的变化趋势来看,不同林分的截留量均为6月最大,7月、8月、9月、10月和5月依次减小,即截留量与降雨量呈正比关系。4种林分枯落物总蓄积量范围为26.3-246.0t/hm^2,其中油松纯林的枯落物储量显著大于其他林分类型（p〈0.05）,侧柏纯林、侧柏—黄栌混交林、元宝枫纯林依次次之,不同林分枯落物的最大持水量和有效持水量的大小排序与之一致。受土壤的物质构成、机械组成、根系的发育状况等因素影响,侧柏纯林的土壤孔隙度和饱和入渗速率（Ks）依次大于侧柏—黄栌混交林、油松纯林和元宝枫纯林。

Hydrological functions of three hydrological function layers of four forest types were investigated in forest stands of rocky and earthy area in Beijing.The traditional measurement methods were used to monitor throughfall,stemflow,interception loss,hydraulics parameters of forest litter and soil.The results indicated that the interception capacity of different vegetation was significantly different,with the maximal canopy interception of stand of mixed Platycladus orientalis（L.）Franco and Cotinus coggygria Scop.（29.1%）,followed by stands of Platycladus orientalis（L.）Franco,Pinus tabuliformis,Acer truncatum.The stem flow ratio of stand Pinus tabuliformis was the highest（5.83%）,which fitted the results obtained in arid and semi-arid region well.At the monthly scale,the maximal interception ratio appeared in June,followed July,August,October and May,and there was a positive correlation between interception and rainfall.The forest litter quantity of four stands ranged from 26.3t/hm^2 to 246.0t/hm^2,and the forest litter quantity of stand Pinus tabuliformis was much greater than the others（p〈0.05）,followed by stands of mixed Platycladus orientalis（L.）Franco and Cotinus coggygria Scop.,Platycladus orientalis（L.）Franco and Acer truncatum,as the same order of the maximum water holding capacity and available interception amount of forest litter.The soil porosity and Ks of stand of mixed Platycladus orientalis（L.）Franco and Cotinus coggygria Scop.were greater than the other stands with the influence of material composition,mechanical composition,root,etc.