Formation, development and degeneration of Tamarix taklamakanensis M.T. Liu community may be affected by wind-sand disturbance. On the basis of field survey and experiments that took eight years from 1994, it was foun...Formation, development and degeneration of Tamarix taklamakanensis M.T. Liu community may be affected by wind-sand disturbance. On the basis of field survey and experiments that took eight years from 1994, it was found that the plant community was formed in wet and low-lying land, developed in sand burying land, and died out in the land with strong wind erosion and severe sand burying. In the initial stage of the community formation, the low-lying land that was formed by wind erosion provided a suitable habitat for seed germination and plant rooting, but salt stress from ground water reduced seedling survival rate. In the developing stage of the community, sand burying stimulated vigorous growth of the shrubs. In the degenerative stage of the community, the wind erosion and sand burying resulted in dying out of the shrubs. It is therefore concluded that wind-sand disturbance has a positive role in the formation and development of the community, and is in a close association with the process of the community degeneration. Taking the habitat of T taklamakanensis into account, it may be appropriate to note that, under the conditions of frequent disturbance and severe stress, desert pioneer species are adaptable and able to survive. This might be a supplement to the CSR strategy.展开更多
Tamarix taklamakanensis,a dominant species in the Taklimakan Desert of China,plays a crucial role in stabilizing sand dunes and maintaining regional ecosystem stability.This study aimed to determine the water use stra...Tamarix taklamakanensis,a dominant species in the Taklimakan Desert of China,plays a crucial role in stabilizing sand dunes and maintaining regional ecosystem stability.This study aimed to determine the water use strategies of T.taklamakanensis in the Taklimakan Desert under a falling groundwater depth.Four typical T.taklamakanensis nabkha habitats(sandy desert of Tazhong site,saline desert-alluvial plain of Qiemo site,desert-oasis ecotone of Qira site and desert-oasis ecotone of Aral site)were selected with different climate,soil,groundwater and plant cover conditions.Stable isotope values of hydrogen and oxygen were measured for plant xylem water,soil water(soil depths within 0–500 cm),snowmelt water and groundwater in the different habitats.Four potential water sources for T.taklamakanensis,defined as shallow,middle and deep soil water,as well as groundwater,were investigated using a Bayesian isotope mixing model.It was found that groundwater in the Taklimakan Desert was not completely recharged by precipitation,but through the river runoff from snowmelt water in the nearby mountain ranges.The surface soil water content was quickly depleted by strong evaporation,groundwater depth was relatively shallow and the height of T.taklamakanensis nabkha was relatively low,thus T.taklamakanensis primarily utilized the middle(23%±1%)and deep(31%±5%)soil water and groundwater(36%±2%)within the sandy desert habitat.T.taklamakanensis mainly used the deep soil water(55%±4%)and a small amount of groundwater(25%±2%)within the saline desert-alluvial plain habitat,where the soil water content was relatively high and the groundwater depth was shallow.In contrast,within the desert-oasis ecotone in the Qira and Aral sites,T.taklamakanensis primarily utilized the deep soil water(35%±1%and 38%±2%,respectively)and may also use groundwater because the height of T.taklamakanensis nabkha was relatively high in these habitats and the soil water content was relatively low,which is associated with the reduced groundwater depth due 展开更多
Under the native habitat conditions, the seasonal gas exchange characteristics of two natural endemic plant species, Calligonum taklimakanensis B.R. Pan & G.M. Shen and Tamarix taklamakanensis M.T. Liu, which are ...Under the native habitat conditions, the seasonal gas exchange characteristics of two natural endemic plant species, Calligonum taklimakanensis B.R. Pan & G.M. Shen and Tamarix taklamakanensis M.T. Liu, which are located in the hinterland of the Taklimakan Desert, are measured and compared by Li-6400 photosynthesis system. The results indicate that temperature (℃), solar radiation (PAR), soil water content (SWC), and other environmental factors have obvious seasonal variations and the gas exchange characteristics of two plants have different changes in different growing seasons. For C. taklimakanensis, both in July and September, its daily changes of net photosynthetic rate tend to be obvious double peak curve, but in July its peak appeared earlier. Besides its maximum net photosynthetic rate (Pmax), apparent quantum efficiency (Φ ), range of effective photosynthetic radiation significantly less than that in September. Moreover, its water use efficiency (WUE) in July was also lower than that in September due to the higher transpiration rate (Tr ). For T. taklamakanensis, although its daily change of net photosynthetic rate is a single peak curve in September, its peak time has not changed, and except that its WUE is higher in September like C. taklimakanensis, the maximum net photosynthetic rate (Pmax), apparent quantum effi- ciency (Φ ), light saturation point, and range of effective photosynthetic radiation has not changed or slightly declined. That is to say C. taklimakanensis select a season that habitat was better (like September) to progress relative effectively photosynthesis accumulation, in contrast, T. taklamakanensis still keep a relatively stable photosynthesis rate in different growth seasons. The difference of gas exchange characteristics of the two plants in different seasons shows that adaptation strategies of the two plants to extreme conditions in desert are different. Besides, both the higher photosynthetic accumulation rate and the higher water use efficiency in September also indicate tha展开更多
文摘Formation, development and degeneration of Tamarix taklamakanensis M.T. Liu community may be affected by wind-sand disturbance. On the basis of field survey and experiments that took eight years from 1994, it was found that the plant community was formed in wet and low-lying land, developed in sand burying land, and died out in the land with strong wind erosion and severe sand burying. In the initial stage of the community formation, the low-lying land that was formed by wind erosion provided a suitable habitat for seed germination and plant rooting, but salt stress from ground water reduced seedling survival rate. In the developing stage of the community, sand burying stimulated vigorous growth of the shrubs. In the degenerative stage of the community, the wind erosion and sand burying resulted in dying out of the shrubs. It is therefore concluded that wind-sand disturbance has a positive role in the formation and development of the community, and is in a close association with the process of the community degeneration. Taking the habitat of T taklamakanensis into account, it may be appropriate to note that, under the conditions of frequent disturbance and severe stress, desert pioneer species are adaptable and able to survive. This might be a supplement to the CSR strategy.
基金supported by the "Research and Development of Sand Prevention Technology of Highway and Soil Erosion Control Technology of Pipelines" of the Strategic Priority Research Program of the Chinese Academy of Sciences "Environmental Changes and Silk Road Civilization in Pan-Third Pole Region"(XDA2003020201)the Key Inter-governmental Projects for International Scientific and Technological Innovation Cooperation of the National Key Research and Development Program of China:"China-Mongolia Cooperation Research and Demonstration in Grassland Desertification Control Technology"(2017YFE0109200)+2 种基金the National Natural Science Foundation of China(41571011,31971731,U1703102)the Key Technical Personnel(Y932111)the Thousand Youth Talents Plan Project(Y472241001)
文摘Tamarix taklamakanensis,a dominant species in the Taklimakan Desert of China,plays a crucial role in stabilizing sand dunes and maintaining regional ecosystem stability.This study aimed to determine the water use strategies of T.taklamakanensis in the Taklimakan Desert under a falling groundwater depth.Four typical T.taklamakanensis nabkha habitats(sandy desert of Tazhong site,saline desert-alluvial plain of Qiemo site,desert-oasis ecotone of Qira site and desert-oasis ecotone of Aral site)were selected with different climate,soil,groundwater and plant cover conditions.Stable isotope values of hydrogen and oxygen were measured for plant xylem water,soil water(soil depths within 0–500 cm),snowmelt water and groundwater in the different habitats.Four potential water sources for T.taklamakanensis,defined as shallow,middle and deep soil water,as well as groundwater,were investigated using a Bayesian isotope mixing model.It was found that groundwater in the Taklimakan Desert was not completely recharged by precipitation,but through the river runoff from snowmelt water in the nearby mountain ranges.The surface soil water content was quickly depleted by strong evaporation,groundwater depth was relatively shallow and the height of T.taklamakanensis nabkha was relatively low,thus T.taklamakanensis primarily utilized the middle(23%±1%)and deep(31%±5%)soil water and groundwater(36%±2%)within the sandy desert habitat.T.taklamakanensis mainly used the deep soil water(55%±4%)and a small amount of groundwater(25%±2%)within the saline desert-alluvial plain habitat,where the soil water content was relatively high and the groundwater depth was shallow.In contrast,within the desert-oasis ecotone in the Qira and Aral sites,T.taklamakanensis primarily utilized the deep soil water(35%±1%and 38%±2%,respectively)and may also use groundwater because the height of T.taklamakanensis nabkha was relatively high in these habitats and the soil water content was relatively low,which is associated with the reduced groundwater depth due
基金Supported by Knowledge Innovating Project of the Chinese Academy of Sciences (CAS) (Grant No. KZCX3-SW-342-02)the Key Project of Ministry of Science and Technology of China (Grant No. 2004BA901A21-1)+2 种基金Key Programs for Science and Technology Development of Xinjiang (Grant No. 200633130)Major Program for Science and Technology of Xinjiang (Grant No. 200733144-2)Knowledge Innovation Project of the Chinese Academy of Sciences (Grant No. KZCX3- SW-342-02)
文摘Under the native habitat conditions, the seasonal gas exchange characteristics of two natural endemic plant species, Calligonum taklimakanensis B.R. Pan & G.M. Shen and Tamarix taklamakanensis M.T. Liu, which are located in the hinterland of the Taklimakan Desert, are measured and compared by Li-6400 photosynthesis system. The results indicate that temperature (℃), solar radiation (PAR), soil water content (SWC), and other environmental factors have obvious seasonal variations and the gas exchange characteristics of two plants have different changes in different growing seasons. For C. taklimakanensis, both in July and September, its daily changes of net photosynthetic rate tend to be obvious double peak curve, but in July its peak appeared earlier. Besides its maximum net photosynthetic rate (Pmax), apparent quantum efficiency (Φ ), range of effective photosynthetic radiation significantly less than that in September. Moreover, its water use efficiency (WUE) in July was also lower than that in September due to the higher transpiration rate (Tr ). For T. taklamakanensis, although its daily change of net photosynthetic rate is a single peak curve in September, its peak time has not changed, and except that its WUE is higher in September like C. taklimakanensis, the maximum net photosynthetic rate (Pmax), apparent quantum effi- ciency (Φ ), light saturation point, and range of effective photosynthetic radiation has not changed or slightly declined. That is to say C. taklimakanensis select a season that habitat was better (like September) to progress relative effectively photosynthesis accumulation, in contrast, T. taklamakanensis still keep a relatively stable photosynthesis rate in different growth seasons. The difference of gas exchange characteristics of the two plants in different seasons shows that adaptation strategies of the two plants to extreme conditions in desert are different. Besides, both the higher photosynthetic accumulation rate and the higher water use efficiency in September also indicate tha
