Study On Dynamic Change Of Soil Moisture And Vegetation Growth In The Small Watershed Of Diediegou Of Liupan Mountains

Considering and optimazing the interrelationship between forest/vegetation and water resources is one of the important subjects for ecological reconstruction and vegetation restoration in the semi-arid zone of Northwest China. In this paper the growth and water use regularities were studied for main vegetation type which is one of the main plantation tree species on north side of the Liupan Mountains. This study is helpful to understand the interrelation between plantation growth and water condition in the semiarid area, and to promote the development of theories and techniques of the restorationan of forest/vegetation in semiarid area. The research conclusions could offer scientific guidance for the harmonious and integrated management of forest and water. The main conclusions were as follows:1. Study on dynamics of soil waterSoil water dynamics during different periods and between different layers: Considering the precipitation during the research period, the soil water seasonal dynamic in different typical plots(0~180cm) can be divided into accumulating period and consuming period and restoring period; soil water dynamics in vertical direction can be divided into soil water variable greatly layer, soil water using layer, soil water subactive using layer and water stable layer.The law of soil water variation in different position on slope: the variance coefficient of soil (0~100 cm) water of Larix principis-rupprechti ahowed a fluctuant rising;The variance coefficient of sunny slope soil water showed a fluctuant rising. The variance coefficient ranged from 22.1% to 38.5%. The variance coefficient of soil water of semi-shady slope showed single peak and the variance coefficient ranged from 23.5% to 43%.2. Hillslopes typical characteristics of vegetation growthLarix principis-rupprechti high growth: Of this study involved Larix principis-rupprechti shade slope in Plantation forest, Its high growth rate can be divided into a slow growth period (5 years after planting) and the rapid growth period (5 ~ 20 years). High-growth year after year there are several factors, the same site of the same age, height growth of trees by tree growth and the impact of spatial characteristics; Different site of the same age, height growth of trees with the soil thickness was positively correlated, followed by the impact of stand density.Stand density and tree height growth is not very high correlation showed that the density can not be good relations between the competition.Shady slope herbaceous vegetation: The Slope of the shade slope there were 29 kinds of plants, each month species richness increased with slope length increased were showed increasing first and then decreasing each month, was clearly a single-front pattern of the central peak appears in the slope.Sunny slope herbaceous vegetation: Sunny slope there were 23 kinds of plant species, species richness to just over a hill from the foot of the slope peak showed a wave-like gradually decreasing trend. In the slope, total biomass increased along the elevation showing a wave-like changes. To below-ground biomass in the lower part of the slope in the plot of the 1-3 largest slope in the upper part of the smallest sample 1-7.Semi-shady slope herbaceous vegetation: The Semi-shady slope, there were 26 kinds of plants, species richness from the foot of the slope to the middle slope changes in the trend of a wave-like by the middle slope is gradually reduced to the slope peak. Total biomass along an altitudinal increase in a wave-like changes. Below-ground biomass trends consistent with the total biomass, and aboveground biomass of the change of in the whole slope is not very clear, we can see the semi-shade slope glass of the trend of total biomass change depending on changes in below-ground biomass. At the same time, It is found that the semi-shade slope each sample plot of above-ground biomass were also significantly less than the below-ground biomass.