This study investigated daily and seasonal changes in sap flow rates of individual trees and their relationships to environmental factors in a 18-year-old Chinese Fir plantation,with an ICT2000TE automatic system(TDP3...This study investigated daily and seasonal changes in sap flow rates of individual trees and their relationships to environmental factors in a 18-year-old Chinese Fir plantation,with an ICT2000TE automatic system(TDP30 probe)from December 2005 to November 2006.A single peak pattern was observed for the daily changes in sap flow rates of individual Chinese Fir tree in fine and overcast days with the peak time occurring at 12:30,while no significant variation and no regular change pattern of sap flow rate were found in rainy days.The daily sap flow was(0.32±0.26),(3.22±2.94),(7.31±3.95)and(2.18±1.10)kg·d-1 in winter,spring,summer and autumn,respectively.For monthly sap flow volume,January was the lowest of 9.21 kg and June the highest of 277.28 kg.The total annual sap flow value was 1 206.89 kg.The relationship between sap flow rate and environmental factors varied with temporal scales.The major factors that affected stem sap flow at less hour scale were solar radiation and air temperature,but on daily scale air temperature,soil water content and solar radiation were the major influencing factors,and on monthly scale air temperature and air relative humidity were the major influencing factors.展开更多
文摘This study investigated daily and seasonal changes in sap flow rates of individual trees and their relationships to environmental factors in a 18-year-old Chinese Fir plantation,with an ICT2000TE automatic system(TDP30 probe)from December 2005 to November 2006.A single peak pattern was observed for the daily changes in sap flow rates of individual Chinese Fir tree in fine and overcast days with the peak time occurring at 12:30,while no significant variation and no regular change pattern of sap flow rate were found in rainy days.The daily sap flow was(0.32±0.26),(3.22±2.94),(7.31±3.95)and(2.18±1.10)kg·d-1 in winter,spring,summer and autumn,respectively.For monthly sap flow volume,January was the lowest of 9.21 kg and June the highest of 277.28 kg.The total annual sap flow value was 1 206.89 kg.The relationship between sap flow rate and environmental factors varied with temporal scales.The major factors that affected stem sap flow at less hour scale were solar radiation and air temperature,but on daily scale air temperature,soil water content and solar radiation were the major influencing factors,and on monthly scale air temperature and air relative humidity were the major influencing factors.
