荒漠防护林典型树种液流特征及其对环境因子的响应

利用基于热补偿理论的SF300分体液流仪对干旱荒漠区人工防护林典型树种(俄罗斯杨、胡杨、榆树、沙枣)树干液流全天候监测,自动气象站同步记录相关环境因子变化。研究表明:①4种防护林树种茎干液流日变化除沙枣树外均存在明显昼夜节律,液流速度在同属种间差异较小,在不同属种间差异显著,俄罗斯杨的日平均液流速度可以达到沙枣的13.8倍,耗水量排序为俄罗斯杨胡杨榆树沙枣树。②水分充足条件下,增加实验地灌溉量使4种树木蒸腾受到抑制,液流流速降低,水分利用效率降低。③液流流速因所处树干径向位点不同而存在差异,俄罗斯杨、榆树、沙枣液流速度表现出由形成层到髓心的递减趋势,胡杨树干径向位点液流没有表现一定规律。④树干液流流速与环境因子进行相关分析,通过逐步回归分析建立了4个典型树种茎干液流速度与环境因子关系估算模型,分析认为4种树木的环境敏感性排序为俄罗斯杨榆树胡杨沙枣。

Characteristics of sap flow of 4 typical shelter-belt tree species and it's relationships with environmental factors in the desert region of Northwest China

Pulse sensors based on the heat compensation theory were applied to measure the stem sap flow of 4 typical tree species in shelter-belt of the desert region in Northwest China. Wind speed, relative humidity, air temperature, soil temperature and leaf temperature were measured at an automatic weather station. The aim of this study was to investigate the diurnal variations of sap flow of different desert trees, and try to understand the characteristics of their water requirements and ecological significance. The results indicated that sap flow rate in Populus Russkii Jabl., P.euphratica Oliv. and Ulmus pumila L. have distinct diurnal variations and the sap flow rates present single-peaks curves, but Elaeagnus angustifolia L. have not been observed clear diurnal pattern in sap flow. The sap flow velocity altered with the probe-inserted depth into the stem. Sap flow velocity had significant diversity among the 4 tree species. Under sufficient soil water content, increase of irrigation can influence on the microhabitat and have an effect to reduce the transpirations. The correlation between the sap flow velocity and the meteorological factors was analyzed. The dynamics of stem sap flows could be fitted well by a regression model based on the meteorological factors. The model could be used to estimate the transpiration of the 4 tree species.