Study On Transpiration Water Consumption And Water Holding Capacity Of Typical Plantation In Loess Hill District

Qingshuihe County is located in the middle of Inner Mongolia Autonomous Region,the ecological environment is very bad,and it is one of the areas with the most serious soil erosion in the middle and upper reaches of the Yellow River.Therefore,how to use water resources efficiently and select afforestation tree species scientifically has become the focus of current research.According to the relationship between transpiration water consumption and environmental factors,and the water holding capacity of litter layer and soil layer,Pinus tabulaeformis,Armeniaca sibirica,Caragana korshinskii were selected as typical afforestation trees in Qingshuihe County,Inner Mongolia)As the research object,EMS62 wrapped plant stem flow measurement system was used to measure the transpiration rate of each tree species,to screen the environmental factors such as solar radiation,air temperature,relative humidity of air,wind speed,and to study the water holding capacity of litter and soil layer under the forest.The conclusions are as follows:(1)The characteristics of the change of sap flow rate of different tree species are obvious day and night.The curve of transpiration rate of apricot and Caragana korshinskii shows a double peak change trend,the peak value appears around 9:00 and 14:00,the curve of transpiration rate of Pinus tabulaeformis shows a single peak change,the peak value appears around 13:30,and the rate of sap flow of the three tree species is small and the change range is relatively stable at night.In typical weather,the maximum daily average sap flow rate of trees is the largest in sunny days,the minimum in rainy days,and the earliest start-up time of trunk sap flow in sunny days,the later the change of transpiration rate into stable period,the later the start-up time of trunk sap flow in rainy days,and the earliest the change of transpiration rate into stable period.(2)The correlation analysis shows that the transpiration rate of each tree species has a significant positive correlation with air temperature,water vapor pressure deficit,solar radiation,wind speed,and a significant negative correlation with air relative humidity.The correlation coefficients of each environmental factor and transpiration rate are solar radiation,air temperature,water vapor pressure deficit,relative humidity and wind speed.The relationship between transpiration rate and environmental factors is linear in the form of Y=A0+A1X1+A2X2+A3X3+A4X4+A5X5.(3)According to the relationship between transpiration water consumption and soil physical properties of tree species,it is found that transpiration rate is negatively related to the maximum soil water holding capacity,capillary water holding capacity,non capillary water holding capacity,capillary porosity,non capillary porosity and total porosity,and positively related to soil bulk density.Among many soil physical indexes,capillary porosity and transpiration rate are most closely related,followed by soil maximum The correlation between water holding capacity and non capillary porosity is the least.According to the study on the water holding capacity of litter layer and soil layer of different forest types,the results showed that the thickness of litter in the non decomposed layer was higher than that in the semi decomposed layer,and that of litter in the non decomposed layer was higher than that in the semi decomposed layer.The maximum thickness of litter in Pinus tabulaeformis was 5.00cm,and that in Caragana korshinskii was 1.45cm.The maximum litter volume of Pinus tabulaeformis was 12.54t�hm-2,and that of Caragana korshinskii was 1.10t�hm-2.The minimum soil bulk density of Pinus tabulaeformis was 1.39g/cm3,and that of Caragana korshinskii was 1.52g/cm3.The maximum water holding capacity of Pinus tabulaeformis and Caragana korshinskii was 35.41g and 28.87g respectively.