神农架2树种树干液流特征及与环境因子关系

采用热扩散探针法和自动气象站，于2018年6-8月对神农架华山松和日本落叶松树干液流和环境因子进行连续观测，分析生长旺季树干液流密度变化规律及其与环境因子的关系。结果表明，日本落叶松生长旺季的月树干液流密度（1 824.80 mL·cm^-2）显著高于华山松（1 026.15 mL·cm^-2）。2个树种晴天树干液流密度均高于雨天，晴天树干液流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。2个树种树干液流主要影响因子不同，在小时尺度下，华山松液流密度的主要影响因子依次是光合有效辐射＞风速＞土壤温度＞土壤含水率＞空气温度＞空气相对湿度＞降水量＞蒸汽压亏缺，而日本落叶松主要影响因子依次是光合有效辐射＞风速＞空气相对湿度＞土壤温度＞蒸汽压亏缺；在日尺度下，华山松液流密度主要影响因子依次是土壤含水率＞蒸汽压亏缺＞光合有效辐射＞降水量＞空气相对湿度＞风速，而日本落叶松主要影响因子依次是光合有效辐射＞蒸汽压亏缺＞土壤含水率＞空气温度。

Characteristics of the Sap Flow and Correlation Analysis with Environmental Factors of Two Tree Species in Shennongjia

By means of thermal dissipation probe(TDP) and automatic weather station,environmental factors and stem sap flow density of Pinus armandii and Larix kaempferi were continuously observed in Shennongjia from June to Autumn in 2018,and the relations between sap flow and environmental factors were analyzed at different time scales.The results showed that the sap flow density of L.kaempferi in growing season was significantly higher(1 824.80 mL·cm^-2·month^-1) than that of P.armandii(1 026.15 mL·cm^-2·month^-1).The sap flow density of two tree species in sunny day was higher than those in rainy day.The daily change of sap flow in sunny day was a single peak curve,while the change law was not obvious in rainy day.At the hour scale,the main environmental factors influencing sap flow density of P.armandii followed the order of photosynthetic active radiation(PAR)>wind speed(WS)>soil temperature(TS)>soil water content(SWC)>air temperature(TA)>relative humidity(RH)>rainfall(R)>vapor pressure deficit(VPD),and the order to L.kaempferi was PAR>WS>RH>TS>VPD.At the day scale,the main environmental factors influencing sap flow density of P.armandii followed the order of SWC>VPD>PAR>R>RH>WS,and the order to L.kaempferi was PAR>VPD>SWC>TA.