不同时间尺度山杏树干液流密度对环境因子的响应

确定不同时间尺度树干液流的主要影响因子，对理解液流密度响应环境的驱动机制提供理论基础。以宁夏黄土丘陵区的山杏为对象，在生长季同步监测树干液流密度、气象要素、土壤环境等指标，分析时、日和月尺度树干液流对环境因子的响应关系。结果表明：1)日尺度上，树干液流与太阳辐射(R_s)、饱和水汽压差(V_PD)、气温(T_a)、相对湿度(R_H)、风速(W_a)、降雨量(P_re)、土壤水分(V_SM)、土壤温度(T_s)8个环境因子相关性极显著；时尺度上，树干液流与除W_a外的其他7个环境因子呈极显著相关；月尺度上，树干液流仅与V_SM、T_a呈极显著相关。2)从时尺度到日尺度，树干液流对V_PD和T_s的响应程度逐渐增强；从日尺度到月尺度，树干液流对R_s、V_PD、T_s的响应程...

Responses of the Tree Trunk Sap Flow Density of Armeniaca sibirica to Environmental Factors in Different Time Scales

The objective of this study was to determine the main influencing factors of tree trunk sap flow (TTSF) at different time scales to provide a theoretical basis for understanding the driving mechanism of liquid flow density in response to the environment.Taking Armeniaca sibirica in the loess hilly region of Ningxia as an example,the TTSF density,meteorological elements,soil environment and other indicators were simultaneously monitored during the growing season,and the response relationships of the TTSF on the hourly,daily and monthly scales to environmental factors were analyzed.The results showed that 1) on the daily scale,the TTSF had extremely significant correlations with eight environmental factors,including solar radiation (R_s),saturated vapor pressure deficit (V_PD),air temperature (T_a),relative humidity (R_H),wind speed (W_a),precipitation (P_re),soil moisture (V_SM),and soil temperature (T_s).On the hourly scale,TTSF was extremely and significantly correlated with 7 other environmental factors except for W_a.On the monthly scale,TTSF was extremely and significantly correlated only to V_SM and T_a.2) From the hourly scale to the daily scale,the response degree of TTSF to V_PD and T_s gradually increased.From daily to monthly scales,the response of TTSF to R_s,V_PD,and T_s gradually weakened,while the response to V_SM gradually increased.On three time scales,the TTSF had positive responses to R_s,T_a,T_s,and VPD,and negative responses to R_H,W_a,and V_SM.3) The relationships between TTSF and environmental factors on three time scales were established.At smaller scales (hour),the selected factors included 7 factors,including R_s and T_a,etc.For the larger scale (month),only one factor (V_SM) was selected.For the intermediate scale (day),four factors were selected,including V_SM and R_s.As the scale changes from hour,day to month,the interpretation rates of TTSF were 61.5%,76.6%,and 80.5%,respectively.The primary influencing factors of TTSF on the hourly and daily scales were R_s,while it was V_SM on the monthly scale.