元谋干热河谷新银合欢林对降水截流的效应

The Effect of Leucaena leucocephala Plantation on Rainfall Interception in the Dry-hot valley in Yuanmou,Yunnan Province

将元谋干热河谷新银合欢林对降雨的再分配过程分成了林冠截流、枯落物截流、土壤截流和地表径流4个层次,对其降水截流效应进行了研究.结果表明：林冠最大截流量为8.1 mm,平均截流量为4.5 mm,最大截流率为56.1％,平均截流率为32.6％,当降雨量大于20 mm时,截流率随着降雨量的增大而迅速下降.林内枯落物最大持水量为8.14～ 20.33 mm,平均为12.52 mm,为干重的2倍以上,枯落物截流降雨150.2 mm,占降雨收入的24.48％.土壤最大蓄水量可达219.9 mm,裸地为182.6 mm,土壤截流为219.9mm,占降雨收入的35.82％.新银合欢林地表径流为43.4 mm,占降雨收入的7.07％,而裸地对照区的地表径流为413.2 mm,占降雨收入的70.3％.人工林群落的地表径流比裸地低63.19％.通过林地的层层截流,有效地降低了土壤侵蚀,具有较好的水文效应.

Three representative plots in a Leucaena leucocephala plantation mixed with other indigenous tree species at the dry hot valley in Yuanmou,Yunnan Province were selected to observe the rainfall interception in the plantation through canopy,litter,soil and surface runoff.The canopy of the plantation was found to intercept 8.1 mm of rainfall at maximum and a mean of 4.5 mm with the maximum rainfall interception rate of 56.1％ and a mean of 32.6 ％.When the rainfall was over 20 mm the rainfall interception rate descended rapidly with the increase in rainfall.The litter had a maximum water-holding content of 8.1-20.3 t · hm-2,and a mean of 12.5 t · hm-2,and the maximum was over two times more than the litter dry weight.The litter intercepted 150.2 mm of rainfall,or 24.48 ％ of the total rainfall.The maximum water-holding capacity was upto 2 198.5 t · hm-2 in the soil but 1 825.6 t · hm-2 in the barren land.The rainfall intercepted by soil was 219.9 mm,accounting for 35.82 ％ of the total rainfall.The surface runoff in the L.leucocephala plantation was 43.4 ram,accounting for 7.07 ％ the total rainfall,while the surface runoff in the bare land was 413.2 mm,accounting for 70.24 ％ of the total rainfall.The surface runoff was 63.19 ％ lower in the plantation than in the barren land.This indicates that the planted forest community effectively reduces soil erosion due to efficient rainfall interception and hence has a good hydrological effect.