天山中部天然云杉林凋落物层水文生态功能研究

Eco-hydrological characteristics of litter of artificial spruce forest in the middle part of Tianshan Mountains

选取了4种不同郁闭度天然云杉林分,通过对凋落物层的蓄积量、最大持水量、最大持水率、吸水速率及有效拦蓄量进行测定分析,研究了其水文生态功能。结果表明:郁闭度为0.8的云杉林分凋落物层蓄积量最大为21.99 t/hm2,而郁闭度为0.2的云杉林分凋落物层蓄积量最小仅为10.20 t/hm2,4种林分凋落物蓄积量变化总体趋势表现为:随着林分郁闭度的不断增大凋落物蓄积量也不断增大;同一郁闭度处林分凋落物不同层次的蓄积量也存在一定的差异性,表现为:半分解层>未分解层。吸水过程中,总体趋势表现为:未分解层与半分解层持水量的变化均较缓慢,但半分解层要比未分解层更为平缓。4种林分未分解层持水量大小顺序为:0.8>0.6>0.4>0.2,半分解层持水量大小顺序为:0.6>0.2>0.8>0.4。

Litter is an important component of forest.It plays a vital role in the normal circulation of materials and keeping the nutrient balance in the forest system.As the second functionary layer in forest hydrologic process,the litter plays an important role in water circulation in the forest land.Litter has a strong ability to hold water,so as to reduce the surface run-off.Tianshan spruce Pinaceae is evergreen tree of gymnosperm,it is a variant of Scheck spruce and a endemic species in China.Large areas of spruce forest distributes in Xinjiang,which not only provide the state with a large number of commodities with the material,but also maintain the ecological balance of forest systems.In order to study the eco-hydrological characteristics of litter of natural spruce forest in the middle part of the Tianshan Mountains,four plots of spruce forest with different canopy densities were selected for this study.The litter preservation,water holding capacity and water absorption speed were determined.The result shows that the litter storage of 0.8 canopy density forest reaches to 21.99 t/hm2,which is the highest in all the forests we studied.Litter storage of 0.2 canopy density forest is only 10.20 t/hm2.In the same litter department,litter storage of the half-decomposed layer is bigger than that of the semi-decomposed layer.The litter's max water holding capacity and water holding ability of 0.8 canopy density forest are the best among the four kinds of litter forests(44.85 t/hm2);0.6 canopy density forest is second(43.45 t/hm2);0.4 canopy density forest is third(41.93 t/hm2);and 0.2 canopy density forest is the lowest(38.96 t/hm2).In terms of litter's water holding characteristic,forest hydrological effects of 0.8 canopy density forest are the best among the four canopy density natural spruce forest.And the paper finds that there is a significant relationship between canopy density and litter layer,it is namely that the litter storage increases with increasing the canopy density.The water-holding capacities of two layers are relatively slow,but the half-decomposed layer is more slowly.For litter un-decomposed or semi-decomposed layer,the water absorption speed is very fast in the beginning 2 hours;within 6 hours water absorption speed drops quickly,after 10 hours water absorption speed is more slowly and 24 hours later water absorption speed stops.The effective water holding depths of litter layer of four canopy density forest are 0.2(2.812 mm),0.4(2.914 mm),0.6(3.383 mm) and 0.8(3.400 mm) respectively.This provides the scientific basis for studding the water conservation and the water source self-control function of the forest litter layer as well as further synthetic evaluation of the Tianshan forest ecology function in this area.