Study On Soil Moisture Content Dynamic Varying Of Pinus Sylvestris Var.Mongolica In Horqin Sandy Land

Soil moisture is an important limiting factor to rebuilt vegetation in semi-arid area, its distribution and content restrict the development of sandy land ecosystem, so the distribution and content of soil moisture are bases for recovery and reconstruction of vegetation in sandy area. In this paper, we select three Mongolian pine(Pinus sylvestris var.Mongolica) fields with various plantation density(400、600、800 strains /hm2) as research object in southern edge of Horqin sandy land, Zhanggutai, Liaoning. Automatic monitoring system is used to continuously and real- time monitor rainfall and soil moisture in Zhanggutai, according to monitoring results, 0~200cm depth of soil moisture changes with time and vertical sect ion are studied, at the same time, water storage of the three density of Mongolian pine is analysed. The results provide references for sustainable development of Mongolian pine in Horqin sandy land. The main results:(1)The results showed that the equation o f water correction for the sandy land was linear function, and the regression equation was y=0.9677*x+0.2635(R2=0.96), which was significantly positively correlated(P<0.01). The validation results showed that the calibration equation of EC H2 O EC-5 sensor for sandy land was stable and reliable and had good applicable effects in measurement for sandy soils.(2)In spring, soil moisture of Mongolian pine is increasing gradually. In summer, with the recharge of precipitation, the soil moisture content is more tha n in spring’s, and the trend of soil moisture is consistent with precipitation. In autumn, soil moisture content decreased, and remained steady in winter eventually. So we divide spring and summer, autumn, winter into water storage stage, water loss stage and water stable stage separately.(3)The soil moisture of three Mongolian pine fields with different density has difference in different layers with soil moisture variation, and according to variation of soil moisture in 0~200cm depth, the soil water condit ion could be divided into three layers: variable layer(0~30cm), utilized layers(30~120cm) and adjustment layer(120~200cm).(4)Soil water storage of three Mongolian pine fields increased gradually and reached the maximum in April; From May to July, soil water storage decreased slowly,but it rised again after a fall in September, with precipitation reduced, soil water storage decreased again in October.