北京山区主要人工林枯落物水文效应

摘要

为探究北京山区主要人工林枯落物水文效应,以北京市怀柔区汤河口镇庄户沟小流域油松、刺槐、侧柏3种林分为研究对象,利用枯落物现存量样地调查、浸泡实验和抗冲槽法,建立枯落物持水量、吸水速率和浸水时间相关关系,定量研究枯落物层水文效应,结果表明:1)3种林分枯落物现存量和总厚度表现为油松最大,分别为6.37t/hm2和4.0cm,其次为刺槐,侧柏最小.2)3种林分枯落物最大持水量为刺槐＞油松＞侧柏,最大持水率为刺槐＞侧柏＞油松；3种林分未分解层和半分解层枯落物的吸水过程表现为0～0.5h内吸水速率最大,4～5h时吸水速率显著减缓；刺槐不同层次枯落物的有效拦蓄量均为最强,总有效拦蓄深为2.6 mm,侧柏总有效拦蓄深最小,为1.0mm.3)不同坡度枯落物覆盖产流产沙实验表明,在相同坡度条件下,产流时间表现为刺槐＞油松＞侧柏＞裸地；径流速率为裸地＞侧柏＞油松＞刺槐；裸地的产流量是3种林地的1.04～1.46倍.%The hydrological effects of forest litters in Pinus tabulaeformis, Robinia pseudoacacia, and Platycladus orientalis forest communities in Zhuanghugou watershed, located in Tanghekou Town, Huairou District of Beijing, were studied in this article. Results show that: 1) The litters amounts and total thickness in Pinus tabulaeformis were the largest, 6. 37 t/hm2 and 4. 0 cm respectively, followed by Robinia pseudoacacia, and the least were in Platycladus orientalis. 2) The largest water-holding capacity of litter was Robinia pseudoacacia > Platycladus orientalis > Pinus tabulaeformis, and the largest water-holding rate was Robinia pseudoacacia > Pinus tabulaeformis > Platycladus orientalis. In the early half hour of water absorption of litter, water-holding rate increased rapidly, and then slightly decreased over time after the 4th to 5 th hour. The effective water holding depth in Robinia pseudoacacia was the highest (2. 6 mm) , and the lowest was in Platycladus orientalis (1.0 mm). 3) It was evident that forest litters could prolong the surface runoff process. In the same slope degree, runoff generation time was given as follows; Robinia pseudoacacia > Pinus tabulaeformis > Platycladus orientalis > bare land, and was runoff velocity bare land > Platycladus orientalis > Pinus tabulaeformis > Robinia pseudoacacia. The runoff amount in bare land was 1. 04 to 1.46 times as great as the three kinds of forests.