赤水河上游主要森林类型水源涵养功能评价

Water Conservation Function Evaluation of Some Main Forest Type in the Upper Reaches of Chishui River

以赤水河上游10种主要森林类型为对象,定量评价其土壤层、枯落物层和林冠层的水源涵养能力。结果表明,枯落物储量为3.24~16.13t/hm^2,有效拦蓄深为0.66~2.38mm,最大失水深为0.14~0.88mm,分解越彻底则蓄水能力越强。土壤层有效持水深为14.35~54.41mm,表现为阔叶林、针阔混交林优于针叶林,并随土层深度增加而降低。土壤层与枯落物层的持水速率均大于失水速率,在1~2h下降快,后期下降慢,与时间呈幂函数关系。阔叶林林冠截留率高于针叶林,可用林外降雨量和林内穿透雨量预测林冠截留量。水源涵养能力主要受枯落物储量、有效拦蓄深、最大失水深和土壤容重、饱和持水量影响,据此将10种森林类型划分为低持水（柏木林、撑绿竹林和火棘＋荚蒾林）、中低持水（杉木林、马尾松＋杉木林）、中持水（马尾松＋柏木林、马尾松-白栎林）和高持水（丝栗栲林、白栎林和马尾松林）4种类型。综合分析表明恢复森林水源涵养功能的核心是调整林冠组成和结构。

A preliminary study on water conservation function of soil layer,litters layer and canopy in the 10 main forest types in the upper reaches of Chishui River.The results showed that the litter storage capacity,the effective water holding depth of litter layer and the maximum water loss depth of litter layer was 3.24~16.13t/hm2,0.66~2.38 mm and 0.14~0.88 mm respectively,the more completely the litters decomposed,the stronger for water holding capacity.The effective water holding depth of soil layer was about 14.35~54.41 mm,where both broad-leaved forest and a mixture of coniferous and broad-leaved were higher than that of coniferous forest,and functioning worse with increasing of soil depth.Water holding speed was higher than that of water loss speed to soil layer and litters layer,and the loss speed decreased sharply in initial 1~2hand later slowly that presented a power function relationship with time.The interception rate with broad-leaved forest was higher than that of coniferous forest,and rainfall and throughfall could predict canopy interception. Water conservation capacity were affected mainly by litter storage,effective water holding depth,maximum water loss depth and soil bulk density,saturated water holding depth.It could be defined four types according to these factors,included low water holding（Cupressus funebris,Bambusa pervariabilis,Pyracantha fortuneana ＋ Viburnum chinshanense）, middle-low water holding（Cunninghamia lanceolata,Pinus massoniana＋Cunninghamia lanceolata）,middle water holding（Pinus massoniana＋Cupressus funebris,Pinus massoniana-Quercus fabri）and high water holding（Castanopsis fargesii,Quercus fabri,Pinus massoniana）.The comprehensive analysis showed that the core role was played in recovering forest water conservation capacity by adjusted the canopy composition and structure.