Luo Chao, Zha Tong Gang, Zhu Meng Xun, Zhu Zhi Jun, Wang Zi Yao, Liu Wen Na
Ministry of Education Forestry Ecological Engineering Research Center,Beijing Forestry University, Beijing 100083, China.
School of Landscape Architecture, Beijing Forestry University, Beijing 100083, China.
Ying Yong Sheng Tai Xue Bao. 2016 May;27(5):1401-1407. doi: 10.13287/j.1001-9332.201605.025.
Water use strategy in growing seasons plays a great role in the management of riparian poplar plantations in northern China. The research was conducted on a poplar (Populus × euramericana cv. '74/76') plantation located near the floodplain of Chaobai River in the northeastern su-burb of Beijing. The influencing factors of poplar sap flow (SF) were presented based on the measurements on the stem SF with thermal dissipation sap flow probe (TDP), soil volumetric water content (VWC) with time-domain-reflectometer (TDR) and environmental factors with eddy cova-riance system from June to July, 2014, to explore the impact of shallow ground water on SF. The results showed that the diurnal variation of SF presented single or double peaks depending on the varia-tion of solar radiation (R). The SF density decreased in soil water relative deficient period (RDP), and the peak time advanced to 12:30 from 14:00, while the time lag between the SF density and R showed no obvious change. The solar radiation and air vapor pressure deficit were the predominant factors of SF during soil water relative sufficient period (RSP), while soil water became the limiting factor in RDP. During the RDP, the daily water consumption of individual poplar tree was significantly negatively correlated with soil VWC at the depth of 100 cm, and significantly positively correlated with soil VWC of the other depths. The shallow ground water (at the depth of ≥150 cm where the soil water content showed little change) might move to the upper soil layer controlled by the capillary force and supply for poplar growth during the soil water-relatively deficient period.
生长季的水分利用策略在中国北方河岸杨树林经营管理中起着重要作用。本研究在北京东北部郊区潮白河漫滩附近的一个杨树（欧美杨无性系‘74/76’）人工林开展。基于2014年6月至7月利用热扩散式茎流探针（TDP）测定的树干茎流（SF）、时域反射仪（TDR）测定的土壤体积含水量（VWC）以及涡度相关系统测定的环境因子，分析了杨树茎流的影响因素，以探究浅层地下水对茎流的影响。结果表明，茎流的日变化根据太阳辐射（R）的变化呈现单峰或双峰。在土壤水分相对亏缺期（RDP），茎流密度降低，峰值时间从14:00提前至12:30，而茎流密度与太阳辐射之间的时间滞后无明显变化。在土壤水分相对充足期（RSP），太阳辐射和空气蒸汽压亏缺是茎流的主要影响因素，而在RDP期土壤水分成为限制因素。在RDP期，单株杨树的日耗水量与100 cm深度处的土壤VWC显著负相关，与其他深度的土壤VWC显著正相关。浅层地下水（在深度≥150 cm处，土壤含水量变化较小）可能在土壤水分相对亏缺期受毛管力作用向上层土壤移动并为杨树生长供水。
