|其他摘要||Soil moisture is the main restrictive factor for the growth of desert vegetation in the Gurbantunggut Desert, is a critical component of water circulation in Soil Plant Atmosphere Continuum, and is the basis for the determination of vegetation carrying capacity and the management of sandy soil moisture. Beishawo, in the southern of Gurbantunggut Desert, was selected as research area, and Haloxylon ammodendron community was selected as studied object. In-situ observation was performed from February 2014 to October 2015，combined with the measure of soil physics characteristics parameter in the laboratory of Fukang Station, the spatial and temporal dynamics of sandy soil moisture, the difference of soil moisture content in the soil layers under the canopy of Haloxylon ammodendron at different growth stages, the influencing factors of spatial difference in sandy soil moisture and the dynamic prediction of sandy soil moisture were researched. The preliminary conclusions can be list as follows:
(1) soil moisture content had obvious temporal variation, and the annual variation of soil moisture content could be divided into 3 periods, i.e., moisture gaining period (from March to May), moisture losing period (from June to October) and moisture stable period (from November to February the following year).
soil moisture content was higher and varied a lot with the depth in 0~30 cm soil layer, soil moisture content was lower and relatively constant with depth in 30~400 cm soil layer; based on the variation coefficients of soil moisture content, the variation coefficients of soil moisture content was higher and varied a lot with the depth in 0~70 cm soil layer, the variation coefficients of soil moisture content was lower and relatively constant with depth in 70~400 cm soil layer.
The difference in soil moisture content was not significant between slope positions, in the west slope, east slope and top of the dune, but it was significant between interdune and the above-mentioned three slope positions, and the soil moisture content in the former was relatively higher; the soil moisture content in the top of the dune was lowest, the difference in soil moisture content was not significant between west slope and east slope, and the soil moisture content in west slope was higher than the soil moisture content in east slope.
(2) The averaged soil moisture content at different life stages in spring, summer, fall, as well as in the whole year displayed a pattern in order of dead individual > adult individual > young individual > bare soil; soil moisture decreased gradually with the increasing distance to the Haloxylon ammodendron base stem within 5 meters; and following rainfall events, the soil moisture content in 10 cm soil increased more in the root zone than in the bare soil.
(3) Rainfall and evaporation had no significant influence on spatial difference of soil moisture content, snowfall, crust and vegetation had significant influence on spatial difference of soil moisture content. On the whole year, the existence of crust increased the evaporation of soil moisture to a certain extent. The wet island effect and shade effect of Haloxylon ammodendron shrub increased the soil moisture content in the interdune to a certain extent. Soil texture had significant influence on spatial difference of soil moisture content. In all, snowfall, vegetation and soil texture resulted in the high soil moisture content in the interdune.
(4) The soil moisture dynamics Haloxylon ammodendron community was simulated with quadratic exponential smoothing model and cubic exponential smoothing model using the soil moisture data in 2014 and 2015. And the soil moisture in a future period of time was forecasted. In the quadratic exponential smoothing model, predictive value was close to measured value, however, the trend of predictive value and measured value was not consistent; in cubic exponential smoothing model, the dynamic trend of predictive value and measured value was consistent.|