摘要
应用热脉冲技术和自动气象站对极端干旱区荒漠河岸林建群种胡杨(Populus euphraticaOliv.)的树干的液流流速及其环境因子进行了为期2a的连续观测,对胡杨树干液流日、季变化及其与环境因子相关性进行了深入的研究。结果表明:胡杨树干液流速率日变化具有明显的昼夜节律性。白天树干液流流速变化曲线呈多峰型。夜间,胡杨同样存在明显的树干液流现象,这主要是由根压引起的。胡杨树干液流速率7月最高,6月、8月次之,9月液流速率高于5月,10月最小,主要生长期6—8月胡杨日均蒸腾量占整个生长季的70%以上。不同林龄的胡杨树干液流速率不同,表现为15龄>25龄>50龄。树干液流量变化与环境因子中气象因子的变化密切相关。逐步回归结果表明,液流速率与净辐射、空气温度、空气相对湿度呈显著线性相关,同时给出了依据常规气象因子估算液流速率的统计模型。
In this paper, the heat pulse technique was applied to study the stem sap flow of Populus euphratica in the desert riparian forest in extreme arid region from April to October of 2003 and from May to October of 2004. The experimental sites are located at Qidaoqiao（41°59′ N, 101°10′ E） and Bayantaolai farm（42°01′ N, 101°14′E） in Ejin county, in the low reach of Heihe river basin. The heat-pulse velocity （HPV） method was used to characterize the spatial and seasonal transpiration variability of Populus euphratica. Estimates of whole-tree transpiration trend to differ by less than 15% from HPV sensors and cut-tree （photometer） measurements. The aim of this study was： （1） to measure transpiration of Populus euphratica, and to establish diurnal, monthly, and annual transpiration velocity of Populus euphratica ; （2）to characterize spatial and seasonal transpiration variability of Populus euphratica in desert riparian forest in extreme arid region; （3）to study stem sap flow at different age of Populus euphratica; （4） to study instantaneous responses of tree water flux to the microclimatic factors, and to establish the statistical model between microclimatic factors and sap flow flux.
The results showed that, Populus euphratica is a fast-transpiring tree species with high daily water consumption, in the natural conditions, its sap flow flux density was 0. 14-0.29 L. cm^-2 · d^-1. The diurnal change of sap flow velocity showed minor fluctuations. At night, the ascent of sap flow could be observed in the above main tree species owning to the existence of root pressure. During the growing season, the maximum of average velocity was observed in July, the second in June and August, that in September was higher than that in May, the minimum occurred in October. From July to August, more than 70 percent occupied the average transpiration during the growing season. The variation of sap flow velocity at different age of Populus euphratica showed that 15 a〉25 a〉50 a. The velocity of sap flow was closely related to the change of micrometeorological factors, the average velocity of sap flow showed prominent linear correlation with net radiation, air temperature, and relative humidity.
出处
《中国沙漠》
CSCD
北大核心
2007年第3期442-447,共6页
Journal of Desert Research
基金
国家自然科学基金项目(40501012和40671010)
中国科学院西部行动计划项目(KZCXZ-XB2-04)
中国气象局气候变化专项项目(CCSF2007-34)共同资助
关键词
极端干旱区
荒漠河岸林
胡杨
树干液流
热脉冲技术
extreme arid region
desert riparian forest
Populus euphratica
sap flow velocity
heat-pulse tech nique
