鄱阳湖典型洲滩湿地植物根系对水分垂向通量的影响

为了定量揭示湿地植物根系的水文效应，采用全物理机制的土壤水分运移数值模型，以鄱阳湖吴城湿地国家自然保护区的茵陈篙群落为例，模拟分析根系引起的水文效应.结果表明，根系将增加土壤饱和含水量与土壤进气值，显著改变土壤水分特征曲线（SWRC）与土壤蓄水能力；在考虑根系影响SWRC下模拟率定的土壤含水量与观测数据的时空变化一致：模型10和50cm观测值与拟合值相关系数由不考虑根系效应下的0.83提高至0.85，10和50cm深度土壤含水量的实测值与模拟值的均方根误差分别减少61%和83%.同时这种率定方法下的模拟相比以往的研究地下水补给根系层水量提高34%；考虑典型的根系效应蒸散发量和累积地下水边界向上通量分别增加10%和150%.而在气候极端干旱条件下地下水向上补给量在根系效应下增加7%~56%，累计差异可达38~312cm，同时蒸散发量增加13%.在植被生长旺季时若地下水埋深较深，则根系效应对蒸散发量的影响会放大.因此在进行相关的湿地生态水文过程和湿地水与物质平衡研究中，建议充分评估湿地植物根系的水文效应，并视计算的工况条件，考虑其水文效应在整个水文过程中的影响.

Impact of typical plant roots on vertical soil water movement in Poyang Lake Wetland: a numerical study

Soil water retention curve (SWRC) governs soil water transport. Plant roots significantly change SWRC, thus affecting the dynamic conditions of soil moisture. In order to quantitatively reveal the hydrological effects of wetland plant roots, this paper used the physical model HYRUS-1D to simulate soil water movement of the Artemisia capillaris community in the Wucheng Wetland National Nature Reserve of Poyang Lake. Roots increased the soil saturated water content and air entry potential, which leads to an increase of soil water content and soil water storage capacity. The calibrated spatial and temporal changes of the observed data of soil water content at different depths are more consistent when considering the root effects on SWRC. The correlation coefficient of the fitting on the with and without considering the root effects were 0.83and 0.85, respectively. The root mean square error of the measured and simulated soil water content at 10cm and 50cm depths decreased by 61% and 83%, respectively. At the same time, the simulation under this calibration method has a difference of up to 34% in groundwater recharge compared with previous studies. Considering the typical root effects under field conditions, the evapotranspiration and cumulative groundwater flux were increased by 10% and 150%, respectively. Under extreme drought conditions, it improved upward flux of the groundwater by 7%~56% with cumulative difference of 38~312cm. Meanwhile, root effects increased evapotranspiration by 13%. Moreover,root effects on evapotranspiration would be amplified if deeper groundwater during the growing season. In the relevant wetland eco-hydrological processes, wetland water and material balance studies, it is recommended to fully assess the hydrological effects of wetland plant roots and consider it throughout the hydrological process based on the calculated working conditions.