Water Conservation Functions Of Two Typical Forests In Liuxihe Catchment Of Guangzhou City

In Liuxihe national forest park which is the most important land of water source for Guangzhou, Phyllestachys pubescens and broad-leaved forest were selected for study, We set the experiment for water conversation function. It is to carry out of crown interception, water holding of litter, infiltration property,surface runoff,watershed turnoff, to reveal water conversation function of Liuxihe.It studies for crown interception of Phyllestachys pubescens and Boradleaf forests from June 2013 to December 2014. The rainfall of broad-leaved forest is 4602.3mm, crown interception is 738.1mm, rate of the crown interception is 22.4%,throughfall is 3757.4mm,rate of the throughfall is 74.4%, stem-flow is 107.5mm,rate of stem-flow is 3.0%. The rainfall of Phyllestachys pubescens is 3757.4mm.,crown interception is552.8mm, rate of the crown interception is 15.9%,throughfall is 3657.0mm,rate of the throughfall is 79.0%,stem-flow is211.0mm, rate of stem-flow is 5.1%.Crown interception, throughfall are positively correlated with rainfall. Stem-flow of broad-leaved forest are logarithmic with rainfall, stem-flow are positively correlated with rainfall. Rate of the crown interception, rate of the throughfall are logarithmic with rainfall. It is not significant related between rate of stem-flow and rainfall.Storage and water-holding capability of litter fall in evergreen broad-leaved forest and Phyllostachys pubescens forest stand in Liuxihe forest park are investigated and analysized. It indicates that:Litter fall storage of evergreen broad-leaved forest is 7.41 t.hm-2, which is 1.7 times that of Phyllostachys pubescens forest stand. Max holding water of litter fall in evergreen broad-leaved forest stand and Phyllostachys pubescens forest stand are 1.23 mm and 0.87 mm, respectively. The relationship between holding water of litter fall and immersion time can be fitted by logarithm equation. Non-decomposed litter of evergreen broad-leaved forest reaches saturation after about 4h, and the saturation time of half-decomposed litter of evergreen broad-leaved forest and Phyllostachys pubescens are 6h to 8h and 8h to lOh, respectively. Water absorption rate decreases with immersion time, and their relationship can be fitted by power function. Water-holding capability of litter fall in evergreen broad-leaved forest is better than that in Phyllostachys pubescens.Soil bulk density of broad-leaved forest is 1.22 g/cm3,capillary porosity and non-capillary porosity are 31.72%,11.51%. Soil bulk density of Phyllestachys pubescens isl.10 g/cm3,capillary porosity and non-capillary porosity are 40.76%n 7.38%.Soil bulk density is positive correlation with soil depth, porosity is negative correlation with soil depth. Water-holding capacity of broad-leaved forest is as 1.5 times as Phyllestachys pubescens. Soil initial infiltration of Phyllestachys pubescensis 27.43mm.min-1,steady infiltration is 9.19 mm.min’1. Soil initial infiltration of broad-leaved forest is 7.33mm.min-1, steady infiltration is 5.17mm.min-1. Soil infiltration is negative correlation with time of infiltration. Soil infiltration is logarithmic with infiltration time.The annual surface runoff of Phyllestachys pubescens is 36.38mm5as 1.3 times as broad-leaved forest. The most surface runoff is July. Surface runoff is positive correlation with rainfall. Surface runoff is positively correlated with rainfall.Average annual watershed of broad-leaved forest is 1391.4mm, as 1.49 times as Phyllestachys pubescens. Average annual runoff coefficient of broad-leaved forest is 0.69, Phyllestachys pubescens is 0.45.Water production of rainy season is higher than dry season. The water production of forest land at Liuxihe in 2008 is 1.45hundred million m3, is Liuxihe reservoir’s 45 percents.