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
The sap flow velocity and the micro-meteorological environment of Sophora japonica f.pendula were measured from Aug.to Oct.2006 with sap flow gauge based on heat balance principle and auto-weather station in Ludong Un...The sap flow velocity and the micro-meteorological environment of Sophora japonica f.pendula were measured from Aug.to Oct.2006 with sap flow gauge based on heat balance principle and auto-weather station in Ludong University.The time lag effect of sap flow compared to meteorological factors was analyzed,and the regressive analysis between comprehensive affecting factor put forward by principal component analysis and sap flow was conducted.The time lag effect analysis results showed that the sap flow lag effect existed compared to total solar radiation,wind speed and photosynthetically active radiation,and the lag time was 10 min,20 min and 10 min,respectively.The time lag effect was the reason of water storage adjustment of leaves,branches and trunks.The sap flow lag time to total solar radiation and photosynthetically active radiation was shorter than wind,because solar radiation affected tree transpiration directly,and the wind affected tree transpiration through affecting boundary resistance of leaves.In the case sap flow time lag considered or not,the determination coefficients between comprehensive meteorological affecting factor and sap flow were 0.830 and 0.944,respectively,and the determination coefficient ascending 13.735% because of lag effect considered.In conclusion,the fitted precision would be improved with the time lag effect of trunk sap flow compared to micro-meteorological factors considered.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.
文摘The sap flow velocity and the micro-meteorological environment of Sophora japonica f.pendula were measured from Aug.to Oct.2006 with sap flow gauge based on heat balance principle and auto-weather station in Ludong University.The time lag effect of sap flow compared to meteorological factors was analyzed,and the regressive analysis between comprehensive affecting factor put forward by principal component analysis and sap flow was conducted.The time lag effect analysis results showed that the sap flow lag effect existed compared to total solar radiation,wind speed and photosynthetically active radiation,and the lag time was 10 min,20 min and 10 min,respectively.The time lag effect was the reason of water storage adjustment of leaves,branches and trunks.The sap flow lag time to total solar radiation and photosynthetically active radiation was shorter than wind,because solar radiation affected tree transpiration directly,and the wind affected tree transpiration through affecting boundary resistance of leaves.In the case sap flow time lag considered or not,the determination coefficients between comprehensive meteorological affecting factor and sap flow were 0.830 and 0.944,respectively,and the determination coefficient ascending 13.735% because of lag effect considered.In conclusion,the fitted precision would be improved with the time lag effect of trunk sap flow compared to micro-meteorological factors considered.
