干热河谷大叶相思树干液流季节动态及其与气象因子的关系

应用热扩散式探针法(TDP)对干热河谷主要造林树种大叶相思的树干液流进行了湿季(7-8月)和干季(1-3月)典型月连续监测,并结合自动气象站对周围气象要素进行同步测定,据此分析液流速率的昼夜、季节变化规律及其与气象因子的关系.结果显示:(1)无论是干季还是湿季,大叶相思树干液流均表现出明显的昼夜变化规律,即呈现“昼高夜低”典型的液流单峰曲线；(2)树干南面液流速率均高于北面,干季南、北方位液流速率最大相差0.0037 cm· s-1,湿季最大相差0.0014cm·s-1；(3)干、湿季液流平均值和最大值具显著差异,湿季树干液流速率平均值和峰值约为干季的2.8倍和2.5倍；(4)大叶相思树干液流速率与光合辐射强度、水汽压亏缺、大气温度、风速呈极显著的正相关关系,而与相对湿度呈极显著负相关关系,按相关程度排序为光合辐射强度＞大气温度＞水汽压亏缺＞相对湿度＞风速,其中,光合有效辐射、相对湿度、水汽压亏缺是影响液流速率的主导因子.

Stem Sap Flow Characteristics of Acacia auriculaeformis in Dry-hot Valley and Their Relations to Meteorological Factors

The thermal dissipation probes(TDP) were applied to measure the sap flow of Acacia auriculaeformis in dry and wet seasons in Yuanmou dry-hot valley, southwest China. The meteorological factors such as photosynthetic active radiation(PAR), air temperature(T), relative humidity(RH), water vapor pressure deficit(VPD) and wind speed were measured at the same time. The diurnal, seasonal variation of liquid flow rate and its relationship with meteorological factors were analyzed. The results indicated: (1)The diurnal variation of sap flow displayed a typical single-peaked curve during the wet and dry seasons. (2)The value of sap flow velocities in south side was higher than that in the north side. (3)There were obviously difference between the wet season and the dry season in the mean and the maximal value of sap flow velocities. The mean and the maximal values of sap flow velocities in wet season were 2.8 and 2.5 times that in dry season. (4)The sap-flow velocity was significantly correlated with PAR, air temperature and VPD and was negatively correlated with the atmospheric relative humidity. The ranking of correlation coefficients was PAR>air temperature>VPD>relative humidity>wind speed. The dominant factors were PAR, RH, and VPD.