The Study On Water Characteritics Of Pinus Tabulaeformis Plantation In Daqing Mountain Of Inner Mongolia

To investigate the water characteritics of Pinus tabulaeformis plantation in arid and semi-arid region.We studied the hydrology characteritics,soil water content and forest growth of different densities Pinus tabulaeformis plantation in Daqing mountain of Innner Mongolia in 2006～2008.With the purpose of providing theoretic foundation and scientific basis for plantation management in semi-arid zone.The main research results were showed as following:(1) There was a significant linear correlation between throughfall and precipitation; The relationship between canopy interception and precipitation was a significant power function;The relationship between stem flow and precipitation was a significant linear function.The mean rate of canopy interception of forest of Pinus tabulaeformis plantation was 34.11%.The relationship between canopy interception and stand density was a significant power function.(2) The relationship between the water capacity of litter production and immersion time was a logarithm function.The relationship of the water absorption speed of litter production and immersion time was a power function.(3) The soil bulk and soil water holding capacity showed significant differences among different soil depths and different stand densities.The saturated hydraulic conductivity decreased as soil depth increased.When the stand density was less than 2000 stock/ha,the mean saturated hydraulic conductivity of 0～60cm soil decreased as stand density increased,and when it was greater than 2000 stock/ha,the saturated hydraulic conductivity of soil increased as stand density increased.(4) Based on equation evaporation theory,using mathematical statistical method to establish the model for computing the soil evapotranspiration of Pinus tabulaeformis plantation:AE=(f+d*E₀)[a+b*exp(cx)].we used this model to compute evapotranspiration of different density plots,the result showed that the evapotranspiratio decreased as the density increased.(5) The rainfall and was the main factor to affect the soil water content dynamic.The CV of soil moisture decreased as soil depth increased.Through dividing the effective threshold of soil moisture,we calculate the effective value of soil moisture of different stand,the result showed that in 2007 years only in July and September the soil moisture could reach the range of middle efficiency water,another months the soil moisture were in the range of difficult efficiency water.The plants of different density stands were under soil water stress.(6) The breast,stem volume and crown biomass per tree of Pinus tabulaeformis plantation decreased as the stand density increased.The relationship between breast. crown biomass and density was power function.The relationship between stem volume and density were linear function.The rate of root increased as the density increased.The growth status of 30a Pinus tabulaeformis plantation in Daqing mountain was not very good.(7) Analyzing the water equilibrium characteristics,The proportion of evapotranspir -ation was 60.19%,and it was the maximal output.(8) By the premise of water equilibrium,computing the soil water carrying capacity of vegetation of Pinus tabulaeformis plantation in Daqing Mountain.It was 3708 stock/ha.