长三角地区典型树种杉木液流速率变化特征

2012年2月—2013年1月,利用热扩散技术和ECH2O系统对南京东善桥林场的杉木(Cunninghamia lanceolata)树干液流速率及相关环境因子进行连续观测,研究分析了杉木液流速率的变化特征。结果显示:不同季节不同天气的杉木液流速率日变化表现出明显的昼夜变化规律,变化曲线表现为单峰曲线。夏季的液流速率最高,峰值为1.45～3.49 kg/h,其次是秋季(0.55～1.91 kg/h),春季的液流速率峰值为0.71～1.44 kg/h,冬季液流速率最低,峰值为0.30～0.85 kg/h。降雨雨量越大,雨后液流速率开始的时间越早,峰值越高,影响持续的时间越长。冬季,降雨开始后液流速率会迅速升高,雨后就会很快降低,而夏季,液流速率会在雨后的白天表现出明显升高,在次日之后会再次降低到原来水平。影响杉木液流速率的主导环境因子存在季节性差异,各相关性系数分别为:春季饱和水气压差(0.884),夏季空气相对湿度(-0.882),秋季饱和水气压差(0.798),冬季林外太阳辐射(0.621),土壤温度是影响杉木日均液流速率的重要环境因子。

The variation characteristics of sap flow of Chinese fir in the Yangtze River Delta

This study was designed to analyze the changing rules of the sap flow rate of Chinese fir(Cunninghamia lanceolata)based on the 12 months continuous located observation of the sap flow rate and environment factors by using sap flow meter and ECH2O system from February 2012 to January 2013 in Dongshanqiao Forest Farm of Nanjing. The results indicated that the sap flow rate of Chinese fir showed distinct diurnal changing rhythms both in sunny and cloudy days in different seasons. The change of the sap flow showed a single-peak curve. The crest values of the sap flow rate in spring, summer, autumn and winter were 0.71-1.44, 1.45-3.49, 0.55-1.91 and 0.30-0.85 kg/h, respectively. The crest value of summer was the highest, that of the winter was the lowest. The greater rainfall, the earlier the sap flow rate starting and the higher peak, the longer of impact. In winter, the sap flow rate increased rapidly when it rained, after the rain the sap flow rate would decrease soon. In summer, the sap flow rate would show obvious rise in the daytime after the rain, and in the later days it would decrease gradually to the original level. There existed seasonal differences for the main environmental factors that influenced the sap flow rate. The main environmental factors of spring, summer, autumn and winter were VPD(0.884), air relative humidity(-0.882), VPD(0.798)and solar radiation in field(0.621). Soil temperature was an important environmental factor that influenced the average daily sap flow rate of Chinese fir.