新疆艾比湖湿地自然保护区胡杨根系水分再分配的估算

根据对新疆艾比湖湿地自然保护区荒漠河岸林的主要建群种胡杨(Populus euphratica)的根系分布特征, 林冠下土壤的饱和容积含水量、最大导水率和根系最大导水率的试验观测数据, 以及对其林冠下5层不同深度土壤容积含水量、土壤水势的动态监测数据, 构建了胡杨根系水分再分配量估算的Ryel模型, 并对胡杨不同季节的水分再分配过程进行了短期模拟。结果表明: (1)胡杨根系水分再分配过程的水分再分配量的最大值出现在艾比湖地方时间凌晨2:30。(2)随着生长季节的变化, 胡杨根系水分再分配的作用逐渐减弱, 并表现出向土壤下层迁移的现象。6月份, 水分再分配过程主要发生在0-40 cm土层, 最大分配量为0.022 0 cm, 夜间总分配量为0.111 0 cm; 8月份水分再分配过程主要发生在10-70 cm土层, 最大分配量为0.006 5 cm, 夜间总分配量为0.018 4 cm; 10月份水分再分配过程主要发生在70-100 cm土层, 最大分配量为0.003 9 cm, 夜间总分配量为0.008 6 cm。

Estimation of hydraulic redistribution of Populus euphratica in Ebinur Lake Wetland Nature Reserve in Xinjiang Uygur Autonomous Region,China

Aims Our objective was to construct and use a Ryel model to quantify hydraulic redistribution of Populus euphratica, a species in desert riparian vegetation.
Methods We constructed a Ryel model to estimate the amount of net water redistribution under the canopy of P. euphratica. We based the model on data from studies measuring the shape and distribution of roots under the canopy of P. euphratica and observing values for volumetric water contents (θ_s), saturated hydraulic conductivity (K_s), maximum radial soil-root conductance of the entire active root system for water (C_RT), soil water potential (ψ_i) and residual volumetric water contents (θ_r) in five soil layers. We used this model to make a short-term simulation of root hydraulic redistribution in different seasons.
Important findings Hydraulic redistribution under the canopy of P. euphratica reached a maximum at 2:30 am. The amount of net water redistribution under the canopy decreased and moved towards the underlying soil with changes in the growing season. In June, hydraulic redistribution mainly occurred in the 0–40 cm soil layer, the maximum amount of redistribution was 0.022 0 cm and the total at night was up to 0.111 0 cm. In August, hydraulic redistribution mainly occurred in the 10–70 cm soil layer, the maximum amount of redistribution was 0.006 5 cm and the total at night was up to 0.018 4 cm. In October, hydraulic redistribution mainly occurred in the 70–100 cm soil layer, the maximum amount of redistribution was 0.003 9 cm and the total at night was up to
0.008 6 cm.