The ratio of transpiration to evapotranspiration (T/ET) is a key parameter for quantifying water use efficiency of ecosystems and understanding the interaction between ecosystem carbon uptake and water cycling in the ...The ratio of transpiration to evapotranspiration (T/ET) is a key parameter for quantifying water use efficiency of ecosystems and understanding the interaction between ecosystem carbon uptake and water cycling in the context of global change.The estimation of T/ET has been paid increasing attention from the scientific community in recent years globally.In this paper,we used the Priestly-Taylor Jet Propulsion Laboratory Model (PT-JPL) driven by regional remote sensing data and gridded meteorological data,to simulate the T/ET in forest ecosystems along the North-South Transect of East China (NSTEC) during 2001-2010,and to analyze the spatial distribution and temporal variation of T/ET,as well as the factors influencing the variation in T/ET.The results showed that:(1) The PT-JPL model is suitable for the simulation of evapotranspiration and its components of forest ecosystems in Eastern China,and has relatively good stability and reliability.(2) Spatial distribution of T/ET in forest ecosystems along NSTEC was heterogeneous,i.e.,T/ET was higher in the north and lower in the south,with an averaged value of 0.69;and the inter-annual variation of T/ET showed a significantly increasing trend,with an increment of 0.007/yr (p<0.01).(3) Seasonal and inter- annual variations of T/ET had different dominant factors.Temperature and EVI can explain around 90%(p<0.01) of the seasonal variation in T/ET,while the inter-annual variation in T/ET was mainly controlled by EVI (53%,p<0.05).展开更多
Soil moisture of Leymus chinensis (Trin.) Tzvel. community has obviously stratified phenomena: the layer (0-40 cm) in which roots are concentrically distributed is directly influenced by precipitation and evapotranspi...Soil moisture of Leymus chinensis (Trin.) Tzvel. community has obviously stratified phenomena: the layer (0-40 cm) in which roots are concentrically distributed is directly influenced by precipitation and evapotranspiration. It can be called interaction layer of precipitation and evapotranspiration. The layer (40-120 cm), where water-storage capacity exchange lagged exchange of the root-layer water-storage capacity and the community evapotranspiration, can be called major water-storage layer. The layer (under 120 cm) can be called water relatively stable/balanced layer. The year 1996 was a normal flow year, and soil water had a surplus of 18 mm at the end of the growing season. The year 1998 was a high flow year, because leakage took place under continuous heavy rainfall, soil water had a deficit of 15 mm at the end of the growing season. Transpiration to evapotranspiration ( T/ET) value reflected not only the luxuriance degree of the community, but also the water use regime of the environmental resources. T/ET value was low (0.5) in May 1998, reaching 0.7 in June, then decreasing to 0.6 in July, due to the impact of rainfall inclining, while August reached the maximum (0.9), and September decreased to 0.6. Water use efficiency (WUE) was mainly restricted by the growing rate of plants under sufficient water condition (1998). Its seasonal changes were coincident with the grand period of growth of the plants. When both meanings of WUE and T/ET were analyzed profoundly, the concept of evapotranspiration efficiency (ETE) which can all-side reflect utilization regime of the environmental water resources was advanced.展开更多
基金National Key Research and Development Program of China,No.2015CB954102National Natural Science Foundation of China,No.31700417,No.41571424
文摘The ratio of transpiration to evapotranspiration (T/ET) is a key parameter for quantifying water use efficiency of ecosystems and understanding the interaction between ecosystem carbon uptake and water cycling in the context of global change.The estimation of T/ET has been paid increasing attention from the scientific community in recent years globally.In this paper,we used the Priestly-Taylor Jet Propulsion Laboratory Model (PT-JPL) driven by regional remote sensing data and gridded meteorological data,to simulate the T/ET in forest ecosystems along the North-South Transect of East China (NSTEC) during 2001-2010,and to analyze the spatial distribution and temporal variation of T/ET,as well as the factors influencing the variation in T/ET.The results showed that:(1) The PT-JPL model is suitable for the simulation of evapotranspiration and its components of forest ecosystems in Eastern China,and has relatively good stability and reliability.(2) Spatial distribution of T/ET in forest ecosystems along NSTEC was heterogeneous,i.e.,T/ET was higher in the north and lower in the south,with an averaged value of 0.69;and the inter-annual variation of T/ET showed a significantly increasing trend,with an increment of 0.007/yr (p<0.01).(3) Seasonal and inter- annual variations of T/ET had different dominant factors.Temperature and EVI can explain around 90%(p<0.01) of the seasonal variation in T/ET,while the inter-annual variation in T/ET was mainly controlled by EVI (53%,p<0.05).
文摘Soil moisture of Leymus chinensis (Trin.) Tzvel. community has obviously stratified phenomena: the layer (0-40 cm) in which roots are concentrically distributed is directly influenced by precipitation and evapotranspiration. It can be called interaction layer of precipitation and evapotranspiration. The layer (40-120 cm), where water-storage capacity exchange lagged exchange of the root-layer water-storage capacity and the community evapotranspiration, can be called major water-storage layer. The layer (under 120 cm) can be called water relatively stable/balanced layer. The year 1996 was a normal flow year, and soil water had a surplus of 18 mm at the end of the growing season. The year 1998 was a high flow year, because leakage took place under continuous heavy rainfall, soil water had a deficit of 15 mm at the end of the growing season. Transpiration to evapotranspiration ( T/ET) value reflected not only the luxuriance degree of the community, but also the water use regime of the environmental resources. T/ET value was low (0.5) in May 1998, reaching 0.7 in June, then decreasing to 0.6 in July, due to the impact of rainfall inclining, while August reached the maximum (0.9), and September decreased to 0.6. Water use efficiency (WUE) was mainly restricted by the growing rate of plants under sufficient water condition (1998). Its seasonal changes were coincident with the grand period of growth of the plants. When both meanings of WUE and T/ET were analyzed profoundly, the concept of evapotranspiration efficiency (ETE) which can all-side reflect utilization regime of the environmental water resources was advanced.
