Study On The Characteristics Of Transpiration Water Consumption And Carrying Capacity Of Artificial Vegetation In Maobula Tributary Areas Across Desert

Water is the most important factor affecting plant growth.In the"soil-plant-atmosphere"continuum system,rainfall is distributed by vegetation canopy into soil,and then returns from soil to atmosphere through transpiration of plants,forming a complete water cycle.Understanding the water distribution and water balance of forest land can provide practical scientific basis for exploring the rationality of vegetation construction,the adjustment of forest structure and the stable maintenance of artificial vegetation.In this study,Tarangaole Town,Hangjin Banner,Ordos,Inner Mongolia,was selected as the research area,which is located in the Maobula Tributary.Three typical artificial vegetation species,namely Salix psammophila,Caragana korshinskii and Artemisia desertorum,were selected as the research objects.Through field investigation and laboratory experiment,soil properties,rainfall redistribution and transpiration characteristics of different vegetation were analyzed.The Hydrus-1D model was used to simulate the precipitation infiltration process,estimate the effective water storage of soil,and comprehensively analyze the bearing capacity of soil water and vegetation on the basis of the water balance theory,so as to provide a theoretical basis for the construction and stable maintenance of vegetation in this area.The main results are as follows:(1)The biomass and root-shoot ratio were in the order of Salix psammophila>Caragana korshinskii>Artemisia desertorum,and the root biomass first increased and then decreased with the increase of soil profile depth.Soil water content increased first and then decreased with the increase of soil depth.The soil bulk density and non-capillary porosity of Salix psammophila were the largest,while that of Artemisia desertorum was the smallest.The soil water capacity,capillary porosity and total porosity were opposite.The soil particles in the study area were mainly sand particles,and the soil p H value was greater than 7.The contents of soil organic matter,total nitrogen,available nitrogen,total phosphorus and available phosphorus decreased with the increase of soil depth.The content of total K and available K in all soil layers was not significant and had no obvious rule.(2)The penetration rainfall of Caragana korshinskii was the largest,the stem flow of Salix psammophila was the largest,and the canopy intercept of Artemisia desertorum,was the largest.According to the regression equation analysis,there is a good linear correlation between the characteristics of rainfall redistribution and rainfall intensity.Wang Yanhui model was used to simulate canopy interception,and the determination coefficients R~2 were 0.81 and 0.86,respectively.The initial infiltration rate,steady infiltration rate and average infiltration rate of soil were in the order of Salix psammophila>Caragana korshinskii>Artemisia desertorum.The simulation results of Kostiakov model and Philip model were relatively good.The average saturated water conductivity of soil was Salix psammophila>Caragana korshinskii>Artemisia desertorum.The variation trend of soil moisture was similar among willow,Caragana korshinskii and Artemisia desertorum.(3)The sap flow density of Salix psammophila,Caragana korshinskii and Artemisia desertorum showed a multi-peak curve during the day,but had no change at night.The fluctuation of daily liquid flow rate in rainy days is greater than that in sunny days,and the total daily liquid flow in rainy days is lower than that in sunny days.The liquid flow rate of willow,Caragana korshinskii and Artemisia desertorum in August was higher than that in other months.The fluctuation trend of daily liquid flow was seasonal,increasing first and then decreasing with time.In the changes of monthly fluid flow,the cumulative monthly fluid flow of Salix psammophila>Caragana korshinskii>Artemisia desertorum,and the monthly fluid flow of Salix psammophila and Caragana korshinskii was September>August>October>July August>September>October>July.(4)Based on the water balance theory,soil water supply and vegetation water consumption were estimated by the Hydraus-1D model and the vegetation water consumption model,and the soil water carrying capacity of the plantation was estimated.The suitable afforestation densities of willow,Caragana Korshinskii and Artemisia ordosica plantation were about 1272/hm~2,2467/hm~2 and 34158/hm~2,respectively.