Abstract:

Soil water holding capacities and infiltration characteristics had been studied in 7 vegetation restoration communities in Nüerzhai watershed in the northwest of Hunan Province in this paper. The results showed: 1) Soil saturated water storage and the maximum water holding capacity in capillary porosity in forest communities were higher than that in wasteland-shrub type, proving that forests had relatively ideal functions of meliorating soil properties and enhancing soil water holding capacity. 2) The common experienced infiltration model was the most suitable model for simulating the infiltrating processes in different vegetation communities in this region, followed by Kostiakov equation,and the Horton equation was the most unsuitable model. 3) The initial and mean infiltration rates of Phyllostachys edulis-Cunninghamia lanceolata mixed forests were the highest, which were 17.10 and 7.42 mm·min^-1respectively, and C. lanceolata plantations had the highest stable infiltration rate (11.51 mm·min^-1). However, Vernicia fordii plantations had the lowest initial infiltration rate (4.93 mm·min^-1), stable infiltration rate (0.52 mm·min^-1) and mean infiltration rate (1.23 mm·min -1). 4) The influence of slope position on the infiltration rate had no obvious regularity; there was the regularity of upslope>middle slope>down slope in Eucommia ulmoides plantations; however, there existed a contrary tendency in Pinus massoniana natural forests, Machilus pingii secondary forests and wasteland-shrub community, that is, the highest was observed in down slope and the lowest in upslope. For C. lanceolata plantations and P. edulis-C. lanceolata mixed forests the highest infiltration rate was observed in upslope and the lowest in middle slope; and in V. fordii plantations the highest in middle slope and the lowest in upslope. 5) According to principal component analysis, the closely relative factors to soil water infiltration properties were picked out, which included soil water holding capacity, porosity, forestry structure, vegetation biomass, elevation, slope degree and slope position, and slope exposure, herbaceous layer coverage ratio and soil density had little bearing on the infiltration. 6) Through double sieving stepwise regression analysis, the driven factor equations of initial infiltration rate, stable infiltration rate and mean infiltration rate had been established.

Key words: vegetation restoration communities, water holding capacity, soil water infiltration, watershed