长三角区麻栎树干液流的季节变化特征

2012-05-2013-04,利用树干液流仪和小气象站对南京东善桥林场的麻栎（Quercus acutissima）树干液流速率及环境因子进行连续观测,研究分析麻栎树干液流的季节变化特征.结果表明：1）春、夏、秋季晴天与阴天的液流速率日变化表现出明显的昼夜变化规律,白天液流速率高于晚上,晴天液流速率高于阴天,而冬季则波动较大;2）春季液流速率平均峰值约为5.69 kg/h,夏、秋、冬季的平均峰值分别约为春季的1.58、1.08、0.012倍;3）春、夏、秋季液流速率峰值与太阳辐射峰值主要存在滞后效应,约1 ～2h,与空气温度、饱和水汽压差、土壤温度的峰值主要存在置前效应,约1 h;4）春、夏、秋季液流速率及日液流量与环境因子的相关系数较高,而冬季的相关系数则较低;5）春、夏、秋季液流速率及其日液流量与环境因子的回归模型决定系数均在0.8左右,而冬季的决定系数较低.

Seasonal variation characteristics of sap flow of Quercus acutissima in the Yangtze River Delta

This study was designed to analyze the seasonal variation characteristics of the sap flow of Quercus acutissima,based on the 12-month continuous located observation of the sap flow rate and environmental factors by using sap flow meter and mini weather station in Nanjing Dongshanqiao Forest from May 2012 to April 2013.The results indicated that：1） the sap flow rate of Q.acutissima showed distinct diurnal change rhythms both in sunny and cloudy days in spring,summer and autumn.Sap flow rates in daytime were higher than those during the night,and sap flow rates in sunny days were higher than those in cloudy days.The fluctuation of the daily sap flow rates was relatively violent in winter.2） The average peak of sap flow rate in spring was about 5.69 kg/h; the average peaks of sap flow rate in summer,autumn and winter were 1.58,1.08 and 0.012 times as high as that in spring.3） The lag effect existed between the peaks of sap flow rate and the peaks of solar radiation,and the lag time was about 1-2 h.The peaks of sap flow rate were about 1 hour ahead of those of air temperature,vapor pressure deficiency and soil temperature.4） The correlation coefficients between environmental factors and sap flow rate and daily sap flow in spring,summer,autumn were higher than in winter.5） The determination coefficients of multiple linear regression models in spring,summer and autumn were around 0.8,and the determination coefficient was lower in winter.