Water Conservation Function Of Alnus Cremastogyne Burk Plantations In North Of Hunan Province

Based on the theory of forestry hydrology, the located research method were adopted. Studied on the hydrological characteristics and water holding function of Alnus cremastogyne artificial forest, Alnus formosana artificial forest and waste land in north of Hunan province from crown canopy, shrub-grass layer, litter layer and soil layer. And water quality of rainfall redistribution were determined.The results are as follows:①In A. cremastogyne types, the relationships of liner, exponential function and puadratic equation were marked among precipitation with throughfall, crowen interception and stemflow. About crowen interception and stemflow, the A.cremastogyne was 16.51% and 5.28%,which were the best.For the different rainfall magnitude, the throughfall,crown interception and canopy interception increased along with the precipitation increased while/,however,the interception rate increased along with the precipitation assumed decreasing progressively tendency.②The water-holding capacity of shrub-grass layer under canopy was inferior.③The order of various chemical element content in the precipitation outside the forest was:Ca>NH4+-N>K>NO3--N>Mg> Fe> Mn> Cu. In throughfall and stemflow of A. cremastogyne artificial forest and A.formosana artificial forest,the element content of K, Fe and Cu assumed the increasing trend.Meanwhile,NH4+-N assumed increasing after decreasing trend.④In A. cremastogyne plantation,the average biomass of litter was 8.27t/hm2,which was higer than in A.s formosana plantation(7.97 t/hm2).The effective store water quantity of litter ranged from 0.13 to 1.70mm.A cremastogyne plantation was the best. There had a relationship of exponential function between soarking time with water-taking rate of litter.⑤The ability of water-holding in A. cremastogyne plantation was obviously better than wasteland. The effective water-holding quantity of soil in A. formosana plantation was 56.82mm, which was 2.1 times more than wasteland. Soil permeability of A. cremastogyne plantation was better than wasteland. The average Soil steady infiltration rate of A. formosana plantation was 2.25mm·min-1, which was 1.18 times more than wasteland. And the average Soil steady infiltration rate of A. formosana plantation was 2.04mm·min-1, which was 1.07 times more than wasteland.As a whole, the water-holding capacity and soil structure could improve markedly for retained plantation.At the same time, A. formosana plantation improves soil penetration storing water ability. Under close situation to the storage capacity of crown canopy, shrub-grass layer and litter layer,Soil water conservation ability of A. formosana plantation was much bettert than others.So that A. formosana plantation has was water conservation function.