【作者】 韩辉； 张学利； 党宏忠； 宋晓东； 孟鹏； 张日升；

【Author】 HAN Hui;ZHANG Xue-li;DANG Hong-zhong;SONG Xiao-dong;MENG Peng;ZHANG Ri-sheng;Institute of Sand-fixation Afforestation Research of Liaoning Province;Zhanggutai Desert Ecosystem Research Station;Institute of Desertification,Chinese Academy of Forestry;

【机构】 辽宁章古台科尔沁沙地生态系统国家定位观测研究站； 辽宁省固沙造林研究所； 中国林业科学研究院荒漠化研究所；

【摘要】 [目的]确定优良固沙树种沙地赤松(Pinus densiflora Sieb.et Zucc.)树干边材液流速率(J_s)方位变化规律,探讨环境因素对方位差异的影响。[方法]采用热扩散式树干液流计(TDP)连续监测树干液流并同步监测环境因素,比较分析不同方位树干液流速率的差异、季节动态及与降水、土壤体积含水率(θ)、太阳辐射强度(R_s)间的关系。[结果]表明:(1)在赤松树干东、南、西、北4个方位上,J_s的日变化与季节变化均呈现出基本一致的格局,且均与R_s间表现出紧密的协同变化关系;(2)在中等强度干旱和极端干旱情况下,各方位边材J_s均同步受到明显抑制,在土壤水分得到充分补充后又快速回升;(3)在典型晴日里,树干各方位边材J_s其午间峰值出现的时刻有差异,呈从早到晚分别是东侧、南侧、西侧、北侧这种顺时针的方位规律;(4)在整个生长季,J_s的日平均值大小一般为南侧>西侧>北侧>东侧,但方位间差异并不显著(P=0.35),北侧J_s的平均值最接近4个方位的平均值(约为平均值的1.01倍)。[结论]为降低观测成本,通过北侧一个方位的测定来估算赤松单株的液流通量具有较好的可靠性;影响赤松各方位液流过程明显变化的θ的阈值为7.5%。更多还原

【Abstract】 [Objective]The knowledge of the azimuthal variation of the sap flow rate of trunks(J_s) is of great significance for accurately estimating the evapotranspiration of individual plants and revealing the water relationship of the trees.[Method]In this study,the sap flow rate of Pinus densiflora Sieb.et Zucc.,an important windbreak and sand fixation species,was monitored continuously during the growing season using a thermal dissipation probe(TDP) method,combined with simultaneous observations of precipitation,soil moisture,and solar radiation and other environmental factors.[Result]By comprehensive analysis,the results show that the daily and seasonal changes of the J_s in the four directions of the trunk,i.e.east,south,west and north,are basically with the same pattern,and all are in accordance with the solar radiation.In moderate-intensity drought and extreme drought conditions,the J_s of each direction was significantly suppressed simultaneously and quickly recovered after the soil moisture was fully replenished.On a typical sunny day,there are differences in the time at which the peaks of the J_s appear at various times.From early to later,it ranked with the order of the east,south,west,and north sides clockwisely.During the whole growing season,the daily mean value of J_s was generally ranked of south>west>north>east,but the difference between directions was not significant(P = 0.35).Statistics show that the average of the J_s in the north side is closest to the average of four azimuths(approximately 1.01 times the average).[Conclusion]The sap flow of each plant is estimated through a measurement on the north side in the actual measurement will get better reliability.in order to reduce the cost of observation.Meanwhile,the threshold value of soil moisture affecting sap flow of Pinus densiflora Sieb.et Zucc.is about 7.5%.更多还原