Haloxylon ammodendron, with its tolerance of drought, high temperature, and salt alkali conditions, is one of the main sand-fixing plant species in the oasis-desert transition zone in China. This study used the TDP30(...Haloxylon ammodendron, with its tolerance of drought, high temperature, and salt alkali conditions, is one of the main sand-fixing plant species in the oasis-desert transition zone in China. This study used the TDP30(where TDP is the thermal dissipation probe) to measure hourly and daily variations in the stem sap flow velocity of H. ammodendron at three age-classes(10, 15, and 20 years old,which were denoted as H10, H15, and H20, respectively) in the Minqin oasis-desert transition zone,China, from May through October 2020. By simultaneously monitoring temperature, relative humidity,photosynthetically active radiation, wind speed, net radiation, rainfall, and soil moisture in this region, we comprehensively investigated the stem sap flow velocity of different-aged H. ammodendron plants(H10,H15, and H20) and revealed its response to physical factors. The results showed that, on sunny days, the hourly variation curves of the stem sap flow velocity of H. ammodendron plants at the three age-classes were mainly unimodal. In addition, the stem sap flow velocity of H. ammodendron plants decreased significantly from September to October, which also delayed its peak time of hourly variation. On rainy days, the stem sap flow velocity of H. ammodendron plants was multimodal and significantly lower than that on sunny days.Average daily water consumption of H. ammodendron plants at H10, H15, and H20 was 1.98, 2.82, and 1.91kg/d, respectively. Temperature was the key factor affecting the stem sap flow velocity of H. ammodendron at all age-classes. Net radiation was the critical factor influencing the stem sap flow velocity of H.ammodendron at H10 and H15;however, for that at H20, it was vapor pressure deficit. The stem sap flow velocity of H. ammodendron was highly significantly correlated with soil moisture at the soil depths of 50and 100 cm, and the correlation was strengthened with increasing stand age. Altogether, our results revealed the dynamic changes of the stem sap flow velocity in different-aged H. ammodendron forest stands and its response mechanism to local physical factors, which provided a theoretical basis for the construction of new protective forests as well as the restoration and protection of existing ones in this region and other similar arid regions in the world.展开更多
[Objectives]This study was conducted to study the variation laws and characteristics of stem sap flow rate in jujube under the injection irrigation mode,to improve the growth quality of jujube trees.[Methods]According...[Objectives]This study was conducted to study the variation laws and characteristics of stem sap flow rate in jujube under the injection irrigation mode,to improve the growth quality of jujube trees.[Methods]According to the characteristics of the growth environment and physiological characteristics of jujube Junzao trees in southern Xinjiang,eight different injection irrigation modes were designed.Through the variation of stem sap flow rate,the most suitable irrigation method for jujube Junzao trees in southern Xinjiang was explored.The variation law of stem sap flow rate of jujube and the effect of meteorological factors on stem sap flow rate of jujube were studied.The variation law of stem sap flow in jujube trees was analyzed,and multiple regression models and time series models were established to predict stem sap flow of jujube trees.[Results]The results showed that the simulation results of the time series model were closer to the actual data,and the model could accurately predict the stem sap flow rate of Junzao.[Conclusions]This study is suitable for the full utilization of water resources in the Tarim Basin in southern Xinjiang,and has important practical significance for analyzing the effect of water stress on the growth and development of jujube trees and precision irrigation.展开更多
The CO_2 released from respiring cells in woody tissues of trees can contribute to one of three fluxes:efflux to the atmosphere(E_A),internal xylem sap transport flux(F_T),and storage flux(DS).Adding those fluxes toge...The CO_2 released from respiring cells in woody tissues of trees can contribute to one of three fluxes:efflux to the atmosphere(E_A),internal xylem sap transport flux(F_T),and storage flux(DS).Adding those fluxes together provides an estimate of actual stem respiration(R_S).We know that the relative proportion of CO_2 in those fluxes varies greatly among tree species,but we do not yet have a clear understanding of the causes for this variation.One possible explanation is that species differ in stem radial CO_2 conductance(g_c).A high g_c would favor the E_A pathway and a low g_cwould favor the F_Tpathway.However,g_chas only been measured once in situ and only in a single tree species.We measured g_cusing two methods in stems of Fraxinus mandshurica Rupr.(ash)and Betula platyphylla Suk.(birch)trees in situ,along with R_S,E_A,F_T and DS.Stem radial CO_2 conductance was substantially greater in ash trees than in birch trees.Corresponding to that finding,in ash trees over 24 h,E_Aconstituted the entire flux of respired CO_2 ,and F_Twas negative,indicating that additional CO_2 ,probably transported from the root system via the xylem,was also diffusing into the atmosphere.In ash trees,F_T was negative over the entire 24 h,and this study represents the first time that has been reported.The addition of xylem-transported CO_2 to E_A caused E_Ato be 9% higher than the actual R_Sover the diel measurement period.Birch trees,which had lower g_c,also had a more commonly seen pattern,with E_A accounting for about 80% of the CO_2 released from local cell respiration and F_T accounting for the remainder.The inorganic carbon concentration in xylem sap was also lower in ash trees than in birch trees:2.7 versus 5.3 mmol L^(-1),respectively.Our results indicate that stem CO_2 conductance could be a very useful measurement to help explain differences among species in the proportion of respired CO_2 that remains in the xylem or diffuses into the atmosphere.展开更多
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
基金supported by the National Natural Science Foundation of China Subsidization Project (32260425, 31860238)the Natural Science Foundation of Gansu Province, China (32060246, 21JR7RA733)。
文摘Haloxylon ammodendron, with its tolerance of drought, high temperature, and salt alkali conditions, is one of the main sand-fixing plant species in the oasis-desert transition zone in China. This study used the TDP30(where TDP is the thermal dissipation probe) to measure hourly and daily variations in the stem sap flow velocity of H. ammodendron at three age-classes(10, 15, and 20 years old,which were denoted as H10, H15, and H20, respectively) in the Minqin oasis-desert transition zone,China, from May through October 2020. By simultaneously monitoring temperature, relative humidity,photosynthetically active radiation, wind speed, net radiation, rainfall, and soil moisture in this region, we comprehensively investigated the stem sap flow velocity of different-aged H. ammodendron plants(H10,H15, and H20) and revealed its response to physical factors. The results showed that, on sunny days, the hourly variation curves of the stem sap flow velocity of H. ammodendron plants at the three age-classes were mainly unimodal. In addition, the stem sap flow velocity of H. ammodendron plants decreased significantly from September to October, which also delayed its peak time of hourly variation. On rainy days, the stem sap flow velocity of H. ammodendron plants was multimodal and significantly lower than that on sunny days.Average daily water consumption of H. ammodendron plants at H10, H15, and H20 was 1.98, 2.82, and 1.91kg/d, respectively. Temperature was the key factor affecting the stem sap flow velocity of H. ammodendron at all age-classes. Net radiation was the critical factor influencing the stem sap flow velocity of H.ammodendron at H10 and H15;however, for that at H20, it was vapor pressure deficit. The stem sap flow velocity of H. ammodendron was highly significantly correlated with soil moisture at the soil depths of 50and 100 cm, and the correlation was strengthened with increasing stand age. Altogether, our results revealed the dynamic changes of the stem sap flow velocity in different-aged H. ammodendron forest stands and its response mechanism to local physical factors, which provided a theoretical basis for the construction of new protective forests as well as the restoration and protection of existing ones in this region and other similar arid regions in the world.
基金Supported by Principal Fund of Tarim University(TDZKQN201708).
文摘[Objectives]This study was conducted to study the variation laws and characteristics of stem sap flow rate in jujube under the injection irrigation mode,to improve the growth quality of jujube trees.[Methods]According to the characteristics of the growth environment and physiological characteristics of jujube Junzao trees in southern Xinjiang,eight different injection irrigation modes were designed.Through the variation of stem sap flow rate,the most suitable irrigation method for jujube Junzao trees in southern Xinjiang was explored.The variation law of stem sap flow rate of jujube and the effect of meteorological factors on stem sap flow rate of jujube were studied.The variation law of stem sap flow in jujube trees was analyzed,and multiple regression models and time series models were established to predict stem sap flow of jujube trees.[Results]The results showed that the simulation results of the time series model were closer to the actual data,and the model could accurately predict the stem sap flow rate of Junzao.[Conclusions]This study is suitable for the full utilization of water resources in the Tarim Basin in southern Xinjiang,and has important practical significance for analyzing the effect of water stress on the growth and development of jujube trees and precision irrigation.
基金supported by the National Natural Science Foundation of China(31670476 and 31100284)the Fundamental Research Funds for the Central Universities(2572016CA02)
文摘The CO_2 released from respiring cells in woody tissues of trees can contribute to one of three fluxes:efflux to the atmosphere(E_A),internal xylem sap transport flux(F_T),and storage flux(DS).Adding those fluxes together provides an estimate of actual stem respiration(R_S).We know that the relative proportion of CO_2 in those fluxes varies greatly among tree species,but we do not yet have a clear understanding of the causes for this variation.One possible explanation is that species differ in stem radial CO_2 conductance(g_c).A high g_c would favor the E_A pathway and a low g_cwould favor the F_Tpathway.However,g_chas only been measured once in situ and only in a single tree species.We measured g_cusing two methods in stems of Fraxinus mandshurica Rupr.(ash)and Betula platyphylla Suk.(birch)trees in situ,along with R_S,E_A,F_T and DS.Stem radial CO_2 conductance was substantially greater in ash trees than in birch trees.Corresponding to that finding,in ash trees over 24 h,E_Aconstituted the entire flux of respired CO_2 ,and F_Twas negative,indicating that additional CO_2 ,probably transported from the root system via the xylem,was also diffusing into the atmosphere.In ash trees,F_T was negative over the entire 24 h,and this study represents the first time that has been reported.The addition of xylem-transported CO_2 to E_A caused E_Ato be 9% higher than the actual R_Sover the diel measurement period.Birch trees,which had lower g_c,also had a more commonly seen pattern,with E_A accounting for about 80% of the CO_2 released from local cell respiration and F_T accounting for the remainder.The inorganic carbon concentration in xylem sap was also lower in ash trees than in birch trees:2.7 versus 5.3 mmol L^(-1),respectively.Our results indicate that stem CO_2 conductance could be a very useful measurement to help explain differences among species in the proportion of respired CO_2 that remains in the xylem or diffuses into the atmosphere.
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.
