神农架华山松树干液流特征及其影响因素

Characteristics of sap flow and its influencing factors of Pinus amandii in Shennongjia

以神农架华山松为研究对象,采用热扩散探针法对树干液流进行连续1 a的测定,结合同步观测的环境因子,分析华山松树干液流规律及其与环境因子的关系。结果表明:(1)华山松树干液流具有明显的昼夜与季节变化规律。全年夜间树干液流量占整日液流量的10.37%,树干液流速率在不同季节表现为夏季>春季>秋季>冬季。(2)不同天气条件下树干液流速率表现为晴天>阴天>雨天,晴天和阴天树干液流速率日变化规律均为单峰曲线,而雨天树干液流日变化规律不明显。(3)空气相对湿度和蒸汽压亏缺为影响华山松树干液流月通量的主要因子。不同季节影响树干液流日通量的主要因子存在差异,春季主要影响因子是太阳总辐射和蒸汽压亏缺;夏季主要影响因子是风速、空气相对湿度和太阳总辐射;秋季主要影响因子是降水量、空气相对湿度、太阳总辐射和蒸汽压亏缺;冬季主要影响因子是空气温度、空气相对湿度和蒸汽压亏缺。

Abstract： Sap flow of Pinus amandii was continuously observed with thermal dissipation probe （TDP） method in Shennongjia from January to December in 2016, and the relations of sap flow to environmental factors collected from automatic weather station were analyzed. The results showed that： （1） The sap flow ofPinus amandii showed significant diurnal and seasonal variations. The sap flow in different seasons showed summer〉spring 〉 autumn 〉 winter. Nocturnal sap flow was 10.37% of the total daily flow in a year. （2） The sap flow rate in different weather conditions showed sunny day 〉 cloudy day 〉 rainy day. The daily change of sap flow rate in sunny and cloudy day was a single peak curve, while the change law was not obvious in rainy day. （3） The main environmental factors influencing monthly sap flow were air relative humidity and VPD. There existed seasonal differences for main environmental factors that influenced the daily sap flow. The daily sap flow was mainly affected by solar radiation and VPD in spring, wind speed, air relative humidity and solar radiation in summer, precipitation, air relative humidity, solar radiation and VPD in autumn, air temperature, air relative humidity and VPD in winter.