Study On Physiology Of Drought Resistanc And Water Dynamic Of Salix Psammophila And Caragana Korshinskii On Sandy Land In Yanchi, Ningxia

This research through two consecutive years observation to the soil moisture of different parts of sandy region , different site types woodland of Salix psammophila and Caragana Korshinskii woodland in Yanchi County of Ningxia province, determining the transpiration rate of Caragana Korshinskii and Salix psammophila in growing season, studied on the physiology of drought resistanc ,discussed the ablity of fight drought of Caragana Korshinskii and Salix psammophila and the distribution patterns and the change rule of soil moisture in different parts of sandy region, different site types woodland of Salix psammophila and Caragana Korshinskii woodland. The results as follows:(1) The result of plant tissue water content showed that the water deficit value of Salix psammophila and Caragana Korshinskii is lower,but they are growing well.Through the different nidex of the leaves'water content of the two plants can be seen the drought resistance of them is different , Salix psammophila is more drought. The change of rule water potential of the two plant is obviously different, Salix psammophila is single peak, Caragana Korshinskii is obvious double peak. Salix psammophila water potential is higher all the time except the early morning,this shows that Caragana Korshinskii need more water to keep higher water potential,also shows that the adaptive capacity of Salix psammophila is stronger than Caragana intermedia's. Salix psammophila has taproot,lateral root is also very developed,the root mostly distributs in the shallower soil,this can make for abtaining larger area precipitation. The taproot of Caragana Korshinskii grows vertically in order to abtain Deep soil moisture.(2) Plants daily transpiration types as follows: Salix psammophila is single peak, Caragana Korshinskii is mixed. Transpiration rate: Salix psammophila 551.36 mg?h-1?g-1, Caragana Korshinskii 316.58 mg?h-1?g-1 Transpiration weighs in growing season: Salix psammophila 226.9mm/m2 Caragana Korshinskii 202.4mm/m2 .(3) The vertical distribution of soil moisture in different research samples appears obviously stratified features, can be divided into three tiers: low soil moisture layer, active soil moisture layer, relative jarless soil moisture layer. The thickness of each layer is different for different site type. Seasonal changes divided into three stages: May soil moisture weak dehydrate stage,June-August on soil water consumption stage, September soil moisture slow recovery phase. Vegetation, atmospheric precipitation and terrain are the main factors affected changes in soil moisture.(4)All the plots'soil moisture appears different levels of profit and loss status in two growing seasons of 2006 and 2007. Because of scarce rainfall in 2006, all the plots'soil moisture have deficits,in which the Salix psammophila woodland that growing in interdual land is the most, -57mm,growing in hilly top is the least, its value is -2.2mm. Because of abundant rainfall in 2007, all the plots'soil moisture have surplus, in which the Salix psammophila woodland that growing in hilly top is the most, its value is 45.64mm,the bottom of sandy region is the least, its value is 2.2mm. According to the degree of profit and loss of soil moisture,the plot can be divided into three species:the soil moisture is in a high degree, moderate degree and minor degree of surplus or deficits.The profit and loss of soil moisture is changed for different time and space.which is different in spatial distribution,because of different root distribution of plant, vegetation types, stand density, site conditions,especially the depth of groundwater.