北京山区刺槐、栓皮栎生长旺季液流特性及影响因子

Sap Flow Characteristics and Influencing Factors of Robinia Pseudoacacia and Quercus Variabilis in Rapid Growth Season in Mountain Area of Beijing City

利用热扩散式树干液流探针于2008年5—9月对北京西山地区刺槐、栓皮栎树干液流进行系统观测,同时结合环境因子的观测数据。分析结果表明,刺槐、栓皮栎树干液流速率的日变化规律在晴天为宽峰或双峰型曲线,阴雨天为多峰型曲线。5,6月,刺槐月平均树干液流速率小于栓皮栎,后者分别是前者的1.58和1.08倍;7—9月,刺槐月平均液流速率大于栓皮栎,前者分别是后者的1.391,1.408和1.450倍。栓皮栎不同高度处树干液流差异明显,5,6月典型晴天树干上位液流速率大于中位和下位,7—9月典型晴天树干下位液流速率大于上位和中位。生长旺季刺槐、栓皮栎树干液流速率均与太阳辐射强度、大气水势和空气水汽压亏缺呈正相关,与土壤水势呈负相关,建立了生长旺季观测期间的树干液流速率与环境因子多元线性回归方程,经F值检验,均达到极显著水平。

Sap flow of Robinia pseudoacacia and Quercus variabilis in the city west mountain area of Beijing City was systematically measured from May to September of 2008 using thermal dissipation sap flow probes,combined with environmental factors.Diurnal variation of sap flow displayed a wide-peaked or double-peaked curve on sunny days and a multiple-peaked curve on overcast and rainy days.In May and June,the averaged sap flow velocities of R.pseudoacacia were 1.58 and 1.08 times slower than those of Q.variabilis,respectively,and in July,August,and September,1.391,1.408,and 1.450 times higher,respectively.In May and June,sap flow velocities of Q.variabilis were significantly faster at upper heights than median and lower heights and from July to September,faster at lower heights than median and upper heights on typical sunny days.During the season of rapid growth,sap flow velocities of both tree species were positively correlated with solar radiation intensity,atmosphere water potential,and vapor pressure deficit and negatively correlated with soil water potential.Multiple linear regression equations for environmental factors with sap flow velocity were established,which all met the significance at 0.01 levels with F test.