Under the guide of system theory, taking the oasis in the Sangong River watershed as a case study, this paper analyzes the oasis structure and function from 4 aspects including oasis spatial structure, water resources...Under the guide of system theory, taking the oasis in the Sangong River watershed as a case study, this paper analyzes the oasis structure and function from 4 aspects including oasis spatial structure, water resources structure, vegetation structure, economic structure and their corresponding functions. The results indicate that as a typical small-scale watershed, Sangong River watershed has the relatively complete mountain-basin structure, and ecological and productive function. Because of human drastic activity the utilization rate of water resources was as high as 98.7%, and the utilization of groundwater was not reasonable, which resulted in an average annual decline of 0.353m in the water table of alluvial-diluvial-fan oasis, and an average annual increase of 0.047m in the alluvial-plain. The layout of crop and shelter forest benefits to the utilization of water and land resources. The development of oasis economy is at low level, and its eco-economic function is weak.展开更多
[Objective] The study aimed to assess the ecosystem services value in Hotan Oasis, Xingjiang. [Method] The visual interpretation method was adopted to process TM/ETM＋ images based on field investigation in Hotan Oasi...[Objective] The study aimed to assess the ecosystem services value in Hotan Oasis, Xingjiang. [Method] The visual interpretation method was adopted to process TM/ETM＋ images based on field investigation in Hotan Oasis. These inter- pretation data, along with two periods of land use data, were reclassified to farm- land, forest, grassland and so on. Then, the ecosystem services value was calculat- ed and analyzed. [Result] Analysis indicated that the ecosystem services value had been increased by 30.44x108 Yuan （16.51%） in the study area during 1980-2010, which can be explained by the increase of glacier and snowfield distributed in the south mountain with the increase of annual precipitation. At the same time, the con- tribution rate of grassland to ecosystem services value had been decreased as a result of degradation of grassland and occupation from farmland. For the whole basin, the increase of ecosystem services value came from the upper reaches, while the ecosystem services value had been reduced in the middle and lower reaches. In the middle reaches, the reduction came mainly from wetland （-1.83x10s Yuan）, waters （-1.68x10s Yuan）, forest （-0.86x108 Yuan） and grassland （-0.80x108 Yuan）. But in the lower reaches, the ecosystem services values of waters, grassland and forest were -0.61 x108 Yuan, -0.24x108 Yuan, and -0.07x10s Yuan, respectively. [Conclusion] If some effective policies, such as the implementation of returning farm- land to forest and ceasing from farming to grazing, would be taken, the ecosystem degradation can be constrained and reversed in the northwest arid region.展开更多
Arid and semi-arid ecosystems exhibit a spatially complex biogeophysical structure. According to arid western special climate-vegetation characters, the fractional cover of photosynthetic vegetation （PV）, non-photos...Arid and semi-arid ecosystems exhibit a spatially complex biogeophysical structure. According to arid western special climate-vegetation characters, the fractional cover of photosynthetic vegetation （PV）, non-photosynthetic vegetation （NPV）, bare soil and water are unmixed, using the remote sensing spectral mixture analysis. We try the method to unmix the canopy funation structure of arid land cover in order to avoid the differentiation of regional vegetation system and the disturbance of environmental background. We developed a modified production efficiency model NPP-PEM appropriate for the arid area at regional scale based on the concept of radiation use efficiency. This model refer to the GLO-PEM and CASA model was driven with remotely sensed observations, and calculates not just the conversion efficiency of absorbed photosynthetically active radiation but also the carbon fluxes that determine net primary productivity （NPP）. We apply and validate the model in the Kaxger and Yarkant river basins in arid western China. The NPP of the study area in 1992 and 1998 was estimated based on the NPP-PEM model. The results show that the improved PEM model, considering the photosynthetical activation of heterogeneous functional vegetation, is in good agreement with field measurements and the existing literature. An accurate agreement （R2= 0.85, P〈0.001） between the estimates and the ground-based measurement was obtained. The spatial distribution of mountain-oasis-desert ecosystem shows an obvious heterogeneous carbon uptake. The results are applicable to arid ecosystem studies ranging from characterizing carbon cycle, carbon flux over arid areas to monitoring change in mountain-oasis-desert productivity, stress and management.展开更多
Wind and sand control are important factors in combating desertification and protecting oases.An oasis protective system can provide these benefits,but quantitative research on protection effects has been lacking to d...Wind and sand control are important factors in combating desertification and protecting oases.An oasis protective system can provide these benefits,but quantitative research on protection effects has been lacking to date.This research describes an oasis protective system in the southeastern border of the Tengger Desert.The system consists of a sand barrier belt,a shrub and herbaceous plant belt,and a farmland shelter belt.The system was compared to a bare dunes area as the control zone.The study investigated windproof effect,sediment transport,and erosion through field observations.Results showed that the roughness of the shrub and herbaceous plant belt,farmland shelter belt,and sand barrier belt were increased compared with bare dunes.The shrub and herbaceous plant belt provided the highest windproof effect values for the same wind velocity measurement height,and the windproof effect values for different protective belts were as follows:shrub and herbaceous plant belt>farmland shelter belt>sand barrier belt.The sand barrier belt provided effective wind and sand control at heights from 0 to 50 cm above the ground.The total sediment transport for each protective belt is as follows:bare dunes>sand barrier belt>shrub and herbaceous plant belt>farmland shelter belt.The sediment transport decreased exponentially as the height increased.In the bare dunes and protective systems,the sediment transport is mainly within 30 cm of the ground surface.The wind erosion intensity for this protective system was as follows:bare dunes>sand barrier belt>shrub and herbaceous plant belt>farmland shelter belt.This research offers quantitative evidence for how oasis protective systems can effectively intercept sand and prevent erosion in oases.The results of this study can be applied in similar regions.展开更多
Human beings have had a tremendous i mpact on natural ecosystems and are n ow the principal power to change the biosphere.It is logical t hat we should pay close attention to t he interaction between human system s an...Human beings have had a tremendous i mpact on natural ecosystems and are n ow the principal power to change the biosphere.It is logical t hat we should pay close attention to t he interaction between human system s and environ-mental systems.Taking Minqin basin,Gansu Province,as a case,this paper focuses on the evolution of regional physi-cal environments and the cultural sy stems by which people maintain their relationships with those environme nts.This pa-per presents the conceptual framewo rk for the man-land system.Expectin g to accelerate the regional sustain able develop-ment,it also analyses the evolution ary mechanism of regional man-land s ystem.On the basis of reviewing and a nalyzing the evolution of man-land system in Minqin basin,the paper also brings fo rward an adjusting mode for the studi ed area,which consists of three aspects:to b uild up a concept that economic growt h must harmonize with environmental quality’s and land productivity’s improvemen t;to make a whole planning and management in the drainage area;and to push for-ward the technique of water-saving i rrigation and establish water-saving agricultural system.It’s meanin gful for resource exploitation and sustainable development of Chinese northwestern arid area,which is represented by Minqin basin,by under-standing what great changes the basin has experienced and is experiencin g at the global background,and studying its time order and territorial structure,th e system’s character and law of evolu tion,trend and the regulating ways t o improve man-land relationship.展开更多
The Hexi Corridor,our study area,is located in Northwest China and is also the most developed area of oasis farming in arid regions of Northwestern China.However,the rapid development of metallurgy and chemical indust...The Hexi Corridor,our study area,is located in Northwest China and is also the most developed area of oasis farming in arid regions of Northwestern China.However,the rapid development of metallurgy and chemical industries in this region poses a great threat to the accumulation of heavy metals in crops.The objectives of this study are(1)to determine the influence of heavy metals on plant growth;(2)to assess the translocation capability of heavy metals in soil-plant system;and(3)to investigate the interaction between heavy metals.Pot experiments were conducted on cole(Brassica campestris L.)grown in the arid oasis soils singly and jointly treated with cadmium(Cd)and lead(Pb).Nine treatments were applied into the pots.Under the same planting conditions,three scenarios of Cd,Pb and Cd–Pb were designed to compare the interaction between Cd and Pb.The results showed that the response of cole weights to Cd,Pb and Cd–Pb treatments was slight,while Cd and Pb uptakes in cole were more sensitive to the single effects of Cd and Pb concentration in soils from the lower treatment levels.Under the influence of the single Cd,Pb and joint Cd–Pb treatments,Cd concentrations were lower in the cole roots than in the shoots,while for Pb,the results were opposite.Comparison studies revealed that the interaction of Cd and Pb could weaken the cole’s ability to uptake,concentrate and translocate heavy metals in arid oasis soils.展开更多
The Hexi Inland River Basin in an arid region of northwestern China was chosen as the study area for this research. The authors define the vulnerability of an oasis social-ecological system to glacier change; select 1...The Hexi Inland River Basin in an arid region of northwestern China was chosen as the study area for this research. The authors define the vulnerability of an oasis social-ecological system to glacier change; select 16 indicators from natural and socioeconomic systems according to exposure, sensitivity, and adaptive capacity; and construct a vulnerability-assessment indicator system aimed at an inland river basin in the arid region of Northwestern China. Vulnerability of the oasis socialecological system affected by glacier change in the study area is evaluated by Spatial Principal Component Analysis(SPCA) under the circumstance of glacier change. The key factors affecting the vulnerability are analyzed. The vulnerability of the oasis social-ecological system in the Hexi Inland River Basin affected by glacier change is of more than medium grade, accounting for about 48.0% of the total number of counties in the study area. In terms of the spatial pattern of the vulnerability, the oasis economic belt is the most vulnerable. With the rapid development of the area's society and economy, the exposure of the system to glacial changes is significantly increased; and an increase in glacial meltwater is not enough to overcome the impact of increased exposure, which is the main reason for the high vulnerability. Based on the result of the vulnerability analysis and combined with the present industrial structure in the Hexi Inland River Basin, near-,medium-, and long-term adaptation initiatives are put forward in the article.展开更多
Croplands are decreasing due to the expansion of urban areas into rural communities and to some extent due to sand accumulations. Increases in population numbers, new development, in addition to the accumulation of sa...Croplands are decreasing due to the expansion of urban areas into rural communities and to some extent due to sand accumulations. Increases in population numbers, new development, in addition to the accumulation of sand and soil salinity are the major driving force leading to abandonment and shrinking of cropland. The aim of this study was to investigate and assess to what extent agricultural lands are affected by urban development in the Al Hassa oasis, Eastern region in Saudi Arabia by employing Landsat time series data of years 1988, 2000 and 2017 as the main source of information. A set of ground truth, control points (GCPs) was also used besides population census data. Unsupervised classifications approach, Normalized Difference Vegetation Index (NDVI) and change detection methods were used here. Urban area during 2000-2017 exhibits much higher increase compared to 1988-2000, while the arable lands declined to −3.4% in 1988-2000 and increased to 22% during 2000-2017. The data analysis results provided new accurate numerical information supported by a graphical representation in regard to the decrease and increase in urban and agricultural lands. Therefore the findings of this study should be considered by decision maker for improving and development the agriculture activities in rural and urban communities.展开更多
The development of oasis along the edge of the Tengerli Desert, where underground water is available, is one of the major strategies to reallocate 'ecological refuges' from their seriously degraded grasslands ...The development of oasis along the edge of the Tengerli Desert, where underground water is available, is one of the major strategies to reallocate 'ecological refuges' from their seriously degraded grasslands to agriculturally cultivable land. Yet, underground water resources, the major constraint, hate not been fully integrated in the development process. Therefore, the decline of water resources and deterioration of water quality caused by over-consumption of water resources has begun to hinder further development and has even fed to the abandonment of some oasis. A system dynamics modeling approach is applied to analyze the water use and water management structures in Yaoba Oasis as a case study. The study attempts to identify the characteristics of major feedback loops, which dominate the over-use of underground water resources leading to the deterioration of water resources in quantity and quality.展开更多
Groundwater is a key factor controlling the growth of vegetation in desert riparian systems. It is important to recognise how groundwater changes affect the riparian forest ecosystem. This information will not only he...Groundwater is a key factor controlling the growth of vegetation in desert riparian systems. It is important to recognise how groundwater changes affect the riparian forest ecosystem. This information will not only help us to understand the ecological and hydrological process of the riparian forest but also provide support for ecological recovery of riparian forests and water-resources management of arid inland river basins. This study aims to estimate the suitability of the Water Vegetation Energy and Solute Modelling(WAVES) model to simulate the Ejina Desert riparian forest ecosystem changes,China, to assess effects of groundwater-depth change on the canopy leaf area index(LAI) and water budgets, and to ascertain the suitable groundwater depth for preserving the stability and structure of desert riparian forest. Results demonstrated that the WAVES model can simulate changes to ecological and hydrological processes. The annual mean water consumption of a Tamarix chinensis riparian forest was less than that of a Populus euphratica riparian forest, and the canopy LAI of the desert riparian forest should increase as groundwater depth decreases. Groundwater changes could significantly influence water budgets for T. chinensis and P. euphratica riparian forests and show the positive and negative effects on vegetation growth and water budgets of riparian forests. Maintaining the annual mean groundwater depth at around 1.7-2.7 m is critical for healthy riparian forest growth. This study highlights the importance of considering groundwater-change impacts on desert riparian vegetation and water-balance applications in ecological restoration and efficient water-resource management in the Heihe River Basin.展开更多
On the basis of the study on areal differentiation of the natural environment of oasis agriculture ecosystems in the Shiyang River Basin, this paper comparatively analyzes the natural productivities, water economic be...On the basis of the study on areal differentiation of the natural environment of oasis agriculture ecosystems in the Shiyang River Basin, this paper comparatively analyzes the natural productivities, water economic benefits, production efficiency, ecological stabilities and developmental conditions of the Wuwei Oasis agricultural ecosystem in the middle reaches of the river basin and the Minqin Oasis agricultural ecosystem in the lower reaches. Under a same management level and investment of . material and energy, primary productiveness and economic benefits of the former are higher than those of the latter. Construction directions of Wuwei and Minqin oases should be different in order to alleviate the water- use contradiction between the middle and lower reaches. The construction objective of Wuwei Oasis should be efficient irrigated farming production system and Minqin Oasis should become a mixed forestry-pastoral-farming ecosystem taking ecological protection as its major function.展开更多
Desert-oasis ecotones are boundary areas between oases and desert ecosystems.Large efforts to control sediment and stabilize these boundaries depend on understanding sedimentary processes,especially aeolian transport ...Desert-oasis ecotones are boundary areas between oases and desert ecosystems.Large efforts to control sediment and stabilize these boundaries depend on understanding sedimentary processes,especially aeolian transport and deposition.Previous studies on aeolian sediment deposition have focused primarily on a single land surface type or a single engineering approach.Few studies have considered deposition in a multi-layer oasis protective system.A complete oasis protective system consists of an outer bare sand area,a sand barrier zone,a shrub and herbaceous plant zone,and a farmland shelter zone.This study used sedimentary analysis to quantify grain-size characteristics in samples from the four land surfaces under different types of weather conditions in the Gelintan oasis of the Tengger Desert,the fourth largest desert in China.The results showed that aeolian sediment deposition decreased from the outer bare sand area through the oasis protective system and into the interior.The four land surface types showed significant differences in deposition volume(P<0.05).Deposited sediment showed gradual decrease in dominant grain-size from sand to silt,but sediment deposited during dust weather contained a larger coarse-grained fraction.From the outer desert to the inner oasis,transport mechanisms shifted from saltation(sand)to suspension(silt and smaller)in non-dust weather.During dust weather,deposition primarily occurs from near-surface aeolian sand transport with saltation.Sediment sorting decreased from exterior to interior zones of the protective system while skewness and kurtosis showed no significant change(P<0.05).These results can help inform strategies for stabilizing and protecting desert-oasis ecotones in this region and other localities.展开更多
Assume that an oasis and its surrounding desert consist of an isolated system without mass and energy exchange with the outer environment.The characteristics of oasis evolution have been explored under the condition o...Assume that an oasis and its surrounding desert consist of an isolated system without mass and energy exchange with the outer environment.The characteristics of oasis evolution have been explored under the condition of system energy conservation.The results show that oasis evolves with two equilibrium states.The first equilibrium suggests a stable expansive and an unstable degraded oasis whereas the second equilibrium indicates a stable shrink and an unstable increase of the oasis area.If one equilibrium state is unstable,the components of the isolated system(oasis and desert) would tend to be no energy exchange and they each reach to energy balance respectively.Oasis would maintain its initial area in this case.Further analyses point out that the two equilibrium states have completely different characteristics.In the first equilibrium state,a higher vegetation albedo,lower soil albedo and larger canopy resistance,and direr soil both contribute to the oasis area expansion,accompanying an excessive large desert soil and vegetation canopy temperature difference(SCTD).In the second equilibrium state,however,a lower vegetation albedo,higher soil albedo and small canopy resistance,and wetter soil benefit the oasis area to stay near its initial value,following a moderate SCTD.The convergent trajectories of the initial values in phase space are influenced by the separatrices of the equilibrium points.Higher temperature is an advantage factor for initial values convergent to the oasis expansion solution.展开更多
Siwa Oasis,one of Egypts most remote settlements,is also a popular tourist destination thanks to the beautiful salt pools with water that people can float in.Salt is both a blessing and a curse in Siwa.Years ago,peopl...Siwa Oasis,one of Egypts most remote settlements,is also a popular tourist destination thanks to the beautiful salt pools with water that people can float in.Salt is both a blessing and a curse in Siwa.Years ago,people started realizing that there was money to be made in the salt trade,and salt mining operations created the salt lakes that the oasis is now famous for.展开更多
The diversity and discontinuity of plant communities in the oasis–desert ecotone are largely shaped by variations in groundwater depth,yet the relationships between spatial distribution patterns and ecological niches...The diversity and discontinuity of plant communities in the oasis–desert ecotone are largely shaped by variations in groundwater depth,yet the relationships between spatial distribution patterns and ecological niches at a regional scale remain insufficiently understood.This study examined the oasis–desert ecotone in Qira County located in the Tarim Basin of China to investigate the spatial distribution of plant communities and groundwater depth as well as their relationships using an integrated approach that combined remote sensing techniques,field monitoring,and numerical modeling.The results showed that vegetation distribution exhibits marked spatial heterogeneity,with coverage ranked as follows:Tamarix ramosissima>Phragmites australis>Populus euphratica>Alhagi sparsifolia.Numerical simulations indicated that groundwater depths range from 2.00 to 65.00 m below the surface,with the system currently in equilibrium,sustaining an average annual recharge of 1.06×10^(8) m^(3) and an average annual discharge of 1.01×10^(8) m^(3).Groundwater depth strongly influences vegetation composition and structure:Phragmites australis dominates at average groundwater depth of 5.83 m,followed by Populus euphratica at average groundwater depth of 7.05 m.As groundwater depth increases,the community is initially predominated by Tamarix ramosissima(average groundwater depth of 8.35 m),then becomes a mixture of Tamarix ramosissima,Populus euphratica,and Karelinia caspia(average groundwater depth of 10.50 m),and finally transitions to Alhagi sparsifolia(average groundwater depth of 14.30 m).These findings highlight groundwater-dependent ecological thresholds that govern plant community composition and provide a scientific basis for biodiversity conservation,ecosystem stability,and vegetation restoration in the arid oasis–desert ecotone.展开更多
Biological soil crusts(BSCs)play crucial roles in improving soil fertility and promoting plants settlement and reproduction in arid areas.However,the specific effects of BSCs on growth status and nutrient accumulation...Biological soil crusts(BSCs)play crucial roles in improving soil fertility and promoting plants settlement and reproduction in arid areas.However,the specific effects of BSCs on growth status and nutrient accumulation of plants are still unclear in different arid areas.This study analyzed the effects of three different BSCs treatments(without crust(WC),intact crust(IC),and broken crust(BC))on the growth,inorganic nutrient absorption,and organic solute synthesis of three typical desert plants(Grubovia dasyphylla(Fisch.&C.A.Mey.)Freitag&G.Kadereit,Nitraria tangutorum Bobrov,and Caragana koraiensis Kom.)in the Minqin desert-oasis ecotone of Northwest China.Results showed that the effects of three BSCs treatments on seed emergence and survival of three plants varied with seed types.The IC treatment significantly hindered the emergence and survival of seeds,while the BC treatment was more conducive to seed emergence and survival of plants.BSCs significantly promoted the growth of three plants,but their effects on plant growth varied at different stages of the growth.Briefly,the growth of G.dasyphylla was affected by BSCs in early stage,but the effects on the growth of G.dasyphylla significantly weakened in the middle and late stages.However,the growth of N.tangutorum and C.koraiensis only showed differences at the middle and late stages,with a significant enhancement in growth.Analysis of variance showed that BSCs,plant species,growth period,and their interactions had significant effects on the biomass and root:shoot ratio of three plants.BSC significantly affected the nutrients absorption and organic solute synthesis in plants.Specifically,BSCs significantly promoted nitrogen(N)absorption in plants and increased plant adaptability in N poor desert ecosystems,but had no significant effects on phosphorus(P)absorption.The effects of BSCs on inorganic nutrient absorption and organic solute synthesis in plants varied significantly among different plant species.The results suggest that BSCs have significant effects on the growth and nutrient accumulation of desert plants,which will provide theoretical basis for exploring the effects of BSCs on desert plant diversity,biodiversity conservation,and ecosystem management measures in arid and semi-arid areas.展开更多
Carbon fluxes are essential indicators assessing vegetation carbon cycle functions.However,the extent and mechanisms by which climate change and human activities influence the spatiotemporal dynamics of carbon fluxes ...Carbon fluxes are essential indicators assessing vegetation carbon cycle functions.However,the extent and mechanisms by which climate change and human activities influence the spatiotemporal dynamics of carbon fluxes in arid oasis and non-oasis area remains unclear.Here,we assessed and predicted the future effects of climate change and human activities on carbon fluxes in the Hexi Corridor.The results showed that the annual average gross primary productivity(GPP),net ecosystem productivity(NEP),and ecosystem respiration(Reco)in the Hexi Corridor oasis increased by 263.91 g C·m^(-2)·yr^(-1),118.45 g C·m^(-2)·yr^(-1)and 122.46 g C·m^(-2)·yr^(-1),respectively,due to the expansion of the oasis area by 3424.84 km^(2) caused by human activities from 2000 to 2022.Both oasis and non-oasis arid ecosystems in the Hexi Corridor acted as carbon sinks.Compared to the non-oasis area,the carbon fluxes contributions of oasis area increased,ranging from 10.21%to 13.99%for GPP,8.50%to11.68%for NEP,and 13.34%to 17.13%for Reco.The contribution of the carbon flux from the oasis expansion area to the total carbon flux change in the Hexi Corridor was 30.96%(7.09 Tg C yr^(-1))for GPP,29.57%(3.39 Tg C yr^(-1))for NEP and 32.40%(3.58 Tg C yr^(-1))for Reco.The changes in carbon fluxes in the oasis area were mainly attributed to human activities(oasis expansion)and temperature,whereas non-oasis area was mainly due to climate factors.Moreover,the future increasing trends were observed for GPP(64.99%),NEP(66.29%)and Reco(82.08%)in the Hexi Corridor.This study provides new insights into the regulatory mechanisms of carbon cycle in the arid oasis and non-oasis area.展开更多
Guazhou County of Gansu Province is a typical ecological fragile area lying in the transition area of desert and oasis.The development of its agricultural economy is highly dependent on natural resources and environme...Guazhou County of Gansu Province is a typical ecological fragile area lying in the transition area of desert and oasis.The development of its agricultural economy is highly dependent on natural resources and environment.Contradiction of resources characterized agriculture and the fragile ecological environment has become one of the main barriers to log the impact of local agriculture to achieve sustainable development.Aiming at fragile ecological environment and limiting factors of agricultural sustainable development,thoughts and countermeasures of realizing agricultural sustainable development have been proposed.展开更多
基金Under the auspices of Project of Western Light Related to Eastern Scholar, the National Natural Science Foundation of China (No. 40471134)
文摘Under the guide of system theory, taking the oasis in the Sangong River watershed as a case study, this paper analyzes the oasis structure and function from 4 aspects including oasis spatial structure, water resources structure, vegetation structure, economic structure and their corresponding functions. The results indicate that as a typical small-scale watershed, Sangong River watershed has the relatively complete mountain-basin structure, and ecological and productive function. Because of human drastic activity the utilization rate of water resources was as high as 98.7%, and the utilization of groundwater was not reasonable, which resulted in an average annual decline of 0.353m in the water table of alluvial-diluvial-fan oasis, and an average annual increase of 0.047m in the alluvial-plain. The layout of crop and shelter forest benefits to the utilization of water and land resources. The development of oasis economy is at low level, and its eco-economic function is weak.
基金Supported by the National Basic Research Program of China (973 Program, 2010CB955905)~~
文摘[Objective] The study aimed to assess the ecosystem services value in Hotan Oasis, Xingjiang. [Method] The visual interpretation method was adopted to process TM/ETM＋ images based on field investigation in Hotan Oasis. These inter- pretation data, along with two periods of land use data, were reclassified to farm- land, forest, grassland and so on. Then, the ecosystem services value was calculat- ed and analyzed. [Result] Analysis indicated that the ecosystem services value had been increased by 30.44x108 Yuan （16.51%） in the study area during 1980-2010, which can be explained by the increase of glacier and snowfield distributed in the south mountain with the increase of annual precipitation. At the same time, the con- tribution rate of grassland to ecosystem services value had been decreased as a result of degradation of grassland and occupation from farmland. For the whole basin, the increase of ecosystem services value came from the upper reaches, while the ecosystem services value had been reduced in the middle and lower reaches. In the middle reaches, the reduction came mainly from wetland （-1.83x10s Yuan）, waters （-1.68x10s Yuan）, forest （-0.86x108 Yuan） and grassland （-0.80x108 Yuan）. But in the lower reaches, the ecosystem services values of waters, grassland and forest were -0.61 x108 Yuan, -0.24x108 Yuan, and -0.07x10s Yuan, respectively. [Conclusion] If some effective policies, such as the implementation of returning farm- land to forest and ceasing from farming to grazing, would be taken, the ecosystem degradation can be constrained and reversed in the northwest arid region.
基金National Project for Basic Research, No.2002CB412507 National key project of fundamental research, No.G1999043500 National Natural Science Foundation of China, No.90202002
文摘Arid and semi-arid ecosystems exhibit a spatially complex biogeophysical structure. According to arid western special climate-vegetation characters, the fractional cover of photosynthetic vegetation （PV）, non-photosynthetic vegetation （NPV）, bare soil and water are unmixed, using the remote sensing spectral mixture analysis. We try the method to unmix the canopy funation structure of arid land cover in order to avoid the differentiation of regional vegetation system and the disturbance of environmental background. We developed a modified production efficiency model NPP-PEM appropriate for the arid area at regional scale based on the concept of radiation use efficiency. This model refer to the GLO-PEM and CASA model was driven with remotely sensed observations, and calculates not just the conversion efficiency of absorbed photosynthetically active radiation but also the carbon fluxes that determine net primary productivity （NPP）. We apply and validate the model in the Kaxger and Yarkant river basins in arid western China. The NPP of the study area in 1992 and 1998 was estimated based on the NPP-PEM model. The results show that the improved PEM model, considering the photosynthetical activation of heterogeneous functional vegetation, is in good agreement with field measurements and the existing literature. An accurate agreement （R2= 0.85, P〈0.001） between the estimates and the ground-based measurement was obtained. The spatial distribution of mountain-oasis-desert ecosystem shows an obvious heterogeneous carbon uptake. The results are applicable to arid ecosystem studies ranging from characterizing carbon cycle, carbon flux over arid areas to monitoring change in mountain-oasis-desert productivity, stress and management.
基金sponsored as a sub-project of the National Key Research and Development Program of China-Desertification Land Management and Sand Industry Technology Research and Development and Demonstration in Inner Mongolia Desertification Area,named Key Techniques and Demonstration of Sand Damage Control in Oasis and Saline-alkali Lake(2016YFC0501003)Central Government’s Special Fund for Guiding Local Science and Technology Development:Inner Mongolia Desertification Control and Innovation Research Center
文摘Wind and sand control are important factors in combating desertification and protecting oases.An oasis protective system can provide these benefits,but quantitative research on protection effects has been lacking to date.This research describes an oasis protective system in the southeastern border of the Tengger Desert.The system consists of a sand barrier belt,a shrub and herbaceous plant belt,and a farmland shelter belt.The system was compared to a bare dunes area as the control zone.The study investigated windproof effect,sediment transport,and erosion through field observations.Results showed that the roughness of the shrub and herbaceous plant belt,farmland shelter belt,and sand barrier belt were increased compared with bare dunes.The shrub and herbaceous plant belt provided the highest windproof effect values for the same wind velocity measurement height,and the windproof effect values for different protective belts were as follows:shrub and herbaceous plant belt>farmland shelter belt>sand barrier belt.The sand barrier belt provided effective wind and sand control at heights from 0 to 50 cm above the ground.The total sediment transport for each protective belt is as follows:bare dunes>sand barrier belt>shrub and herbaceous plant belt>farmland shelter belt.The sediment transport decreased exponentially as the height increased.In the bare dunes and protective systems,the sediment transport is mainly within 30 cm of the ground surface.The wind erosion intensity for this protective system was as follows:bare dunes>sand barrier belt>shrub and herbaceous plant belt>farmland shelter belt.This research offers quantitative evidence for how oasis protective systems can effectively intercept sand and prevent erosion in oases.The results of this study can be applied in similar regions.
文摘Human beings have had a tremendous i mpact on natural ecosystems and are n ow the principal power to change the biosphere.It is logical t hat we should pay close attention to t he interaction between human system s and environ-mental systems.Taking Minqin basin,Gansu Province,as a case,this paper focuses on the evolution of regional physi-cal environments and the cultural sy stems by which people maintain their relationships with those environme nts.This pa-per presents the conceptual framewo rk for the man-land system.Expectin g to accelerate the regional sustain able develop-ment,it also analyses the evolution ary mechanism of regional man-land s ystem.On the basis of reviewing and a nalyzing the evolution of man-land system in Minqin basin,the paper also brings fo rward an adjusting mode for the studi ed area,which consists of three aspects:to b uild up a concept that economic growt h must harmonize with environmental quality’s and land productivity’s improvemen t;to make a whole planning and management in the drainage area;and to push for-ward the technique of water-saving i rrigation and establish water-saving agricultural system.It’s meanin gful for resource exploitation and sustainable development of Chinese northwestern arid area,which is represented by Minqin basin,by under-standing what great changes the basin has experienced and is experiencin g at the global background,and studying its time order and territorial structure,th e system’s character and law of evolu tion,trend and the regulating ways t o improve man-land relationship.
基金supported by the National Natural Science Foundation of China(51178209,91025015)the Fundamental Research Funds for the Central Universities in Lanzhou University(lzujbky-2011-66)
文摘The Hexi Corridor,our study area,is located in Northwest China and is also the most developed area of oasis farming in arid regions of Northwestern China.However,the rapid development of metallurgy and chemical industries in this region poses a great threat to the accumulation of heavy metals in crops.The objectives of this study are(1)to determine the influence of heavy metals on plant growth;(2)to assess the translocation capability of heavy metals in soil-plant system;and(3)to investigate the interaction between heavy metals.Pot experiments were conducted on cole(Brassica campestris L.)grown in the arid oasis soils singly and jointly treated with cadmium(Cd)and lead(Pb).Nine treatments were applied into the pots.Under the same planting conditions,three scenarios of Cd,Pb and Cd–Pb were designed to compare the interaction between Cd and Pb.The results showed that the response of cole weights to Cd,Pb and Cd–Pb treatments was slight,while Cd and Pb uptakes in cole were more sensitive to the single effects of Cd and Pb concentration in soils from the lower treatment levels.Under the influence of the single Cd,Pb and joint Cd–Pb treatments,Cd concentrations were lower in the cole roots than in the shoots,while for Pb,the results were opposite.Comparison studies revealed that the interaction of Cd and Pb could weaken the cole’s ability to uptake,concentrate and translocate heavy metals in arid oasis soils.
基金supported by the Global Change Research Program of China (2013CBA01808)the China National Natural Science Foundation (41271088)
文摘The Hexi Inland River Basin in an arid region of northwestern China was chosen as the study area for this research. The authors define the vulnerability of an oasis social-ecological system to glacier change; select 16 indicators from natural and socioeconomic systems according to exposure, sensitivity, and adaptive capacity; and construct a vulnerability-assessment indicator system aimed at an inland river basin in the arid region of Northwestern China. Vulnerability of the oasis socialecological system affected by glacier change in the study area is evaluated by Spatial Principal Component Analysis(SPCA) under the circumstance of glacier change. The key factors affecting the vulnerability are analyzed. The vulnerability of the oasis social-ecological system in the Hexi Inland River Basin affected by glacier change is of more than medium grade, accounting for about 48.0% of the total number of counties in the study area. In terms of the spatial pattern of the vulnerability, the oasis economic belt is the most vulnerable. With the rapid development of the area's society and economy, the exposure of the system to glacial changes is significantly increased; and an increase in glacial meltwater is not enough to overcome the impact of increased exposure, which is the main reason for the high vulnerability. Based on the result of the vulnerability analysis and combined with the present industrial structure in the Hexi Inland River Basin, near-,medium-, and long-term adaptation initiatives are put forward in the article.
文摘Croplands are decreasing due to the expansion of urban areas into rural communities and to some extent due to sand accumulations. Increases in population numbers, new development, in addition to the accumulation of sand and soil salinity are the major driving force leading to abandonment and shrinking of cropland. The aim of this study was to investigate and assess to what extent agricultural lands are affected by urban development in the Al Hassa oasis, Eastern region in Saudi Arabia by employing Landsat time series data of years 1988, 2000 and 2017 as the main source of information. A set of ground truth, control points (GCPs) was also used besides population census data. Unsupervised classifications approach, Normalized Difference Vegetation Index (NDVI) and change detection methods were used here. Urban area during 2000-2017 exhibits much higher increase compared to 1988-2000, while the arable lands declined to −3.4% in 1988-2000 and increased to 22% during 2000-2017. The data analysis results provided new accurate numerical information supported by a graphical representation in regard to the decrease and increase in urban and agricultural lands. Therefore the findings of this study should be considered by decision maker for improving and development the agriculture activities in rural and urban communities.
文摘The development of oasis along the edge of the Tengerli Desert, where underground water is available, is one of the major strategies to reallocate 'ecological refuges' from their seriously degraded grasslands to agriculturally cultivable land. Yet, underground water resources, the major constraint, hate not been fully integrated in the development process. Therefore, the decline of water resources and deterioration of water quality caused by over-consumption of water resources has begun to hinder further development and has even fed to the abandonment of some oasis. A system dynamics modeling approach is applied to analyze the water use and water management structures in Yaoba Oasis as a case study. The study attempts to identify the characteristics of major feedback loops, which dominate the over-use of underground water resources leading to the deterioration of water resources in quantity and quality.
基金supported by the National Key Research and Development program (2016YFC0400908)the National Natural Science Foundation of China (Nos. 41101026, 31370466)the STS project of Chinese academy of sciences (29Y829731)
文摘Groundwater is a key factor controlling the growth of vegetation in desert riparian systems. It is important to recognise how groundwater changes affect the riparian forest ecosystem. This information will not only help us to understand the ecological and hydrological process of the riparian forest but also provide support for ecological recovery of riparian forests and water-resources management of arid inland river basins. This study aims to estimate the suitability of the Water Vegetation Energy and Solute Modelling(WAVES) model to simulate the Ejina Desert riparian forest ecosystem changes,China, to assess effects of groundwater-depth change on the canopy leaf area index(LAI) and water budgets, and to ascertain the suitable groundwater depth for preserving the stability and structure of desert riparian forest. Results demonstrated that the WAVES model can simulate changes to ecological and hydrological processes. The annual mean water consumption of a Tamarix chinensis riparian forest was less than that of a Populus euphratica riparian forest, and the canopy LAI of the desert riparian forest should increase as groundwater depth decreases. Groundwater changes could significantly influence water budgets for T. chinensis and P. euphratica riparian forests and show the positive and negative effects on vegetation growth and water budgets of riparian forests. Maintaining the annual mean groundwater depth at around 1.7-2.7 m is critical for healthy riparian forest growth. This study highlights the importance of considering groundwater-change impacts on desert riparian vegetation and water-balance applications in ecological restoration and efficient water-resource management in the Heihe River Basin.
文摘On the basis of the study on areal differentiation of the natural environment of oasis agriculture ecosystems in the Shiyang River Basin, this paper comparatively analyzes the natural productivities, water economic benefits, production efficiency, ecological stabilities and developmental conditions of the Wuwei Oasis agricultural ecosystem in the middle reaches of the river basin and the Minqin Oasis agricultural ecosystem in the lower reaches. Under a same management level and investment of . material and energy, primary productiveness and economic benefits of the former are higher than those of the latter. Construction directions of Wuwei and Minqin oases should be different in order to alleviate the water- use contradiction between the middle and lower reaches. The construction objective of Wuwei Oasis should be efficient irrigated farming production system and Minqin Oasis should become a mixed forestry-pastoral-farming ecosystem taking ecological protection as its major function.
基金sponsored as a sub-project of the National Key Research and Development Program of China-Desertification Land Management and Sand Industry Technology Research and Development and Demonstration in Inner Mongolia Desertification Area,named Key Techniques and Demonstration of Sand Damage Control in Oasis and Saline-alkali Lake(2016YFC0501003)a sub-project of the National Key Research and Development Program of Study on Restoration and Protection of Typical Fragile Ecology,named Study and Demonstration of Sand-fixing and Wind-breaking Techniques of Cyperus Esculentus L.in North Wind-blown Sand Region(2019YFC0507600)。
文摘Desert-oasis ecotones are boundary areas between oases and desert ecosystems.Large efforts to control sediment and stabilize these boundaries depend on understanding sedimentary processes,especially aeolian transport and deposition.Previous studies on aeolian sediment deposition have focused primarily on a single land surface type or a single engineering approach.Few studies have considered deposition in a multi-layer oasis protective system.A complete oasis protective system consists of an outer bare sand area,a sand barrier zone,a shrub and herbaceous plant zone,and a farmland shelter zone.This study used sedimentary analysis to quantify grain-size characteristics in samples from the four land surfaces under different types of weather conditions in the Gelintan oasis of the Tengger Desert,the fourth largest desert in China.The results showed that aeolian sediment deposition decreased from the outer bare sand area through the oasis protective system and into the interior.The four land surface types showed significant differences in deposition volume(P<0.05).Deposited sediment showed gradual decrease in dominant grain-size from sand to silt,but sediment deposited during dust weather contained a larger coarse-grained fraction.From the outer desert to the inner oasis,transport mechanisms shifted from saltation(sand)to suspension(silt and smaller)in non-dust weather.During dust weather,deposition primarily occurs from near-surface aeolian sand transport with saltation.Sediment sorting decreased from exterior to interior zones of the protective system while skewness and kurtosis showed no significant change(P<0.05).These results can help inform strategies for stabilizing and protecting desert-oasis ecotones in this region and other localities.
基金supported by the National Basic Research Program of China(Grant No.2014CB953903)the Fundamental Research Funds for the Central Universities(Grant No.2013YB45)
文摘Assume that an oasis and its surrounding desert consist of an isolated system without mass and energy exchange with the outer environment.The characteristics of oasis evolution have been explored under the condition of system energy conservation.The results show that oasis evolves with two equilibrium states.The first equilibrium suggests a stable expansive and an unstable degraded oasis whereas the second equilibrium indicates a stable shrink and an unstable increase of the oasis area.If one equilibrium state is unstable,the components of the isolated system(oasis and desert) would tend to be no energy exchange and they each reach to energy balance respectively.Oasis would maintain its initial area in this case.Further analyses point out that the two equilibrium states have completely different characteristics.In the first equilibrium state,a higher vegetation albedo,lower soil albedo and larger canopy resistance,and direr soil both contribute to the oasis area expansion,accompanying an excessive large desert soil and vegetation canopy temperature difference(SCTD).In the second equilibrium state,however,a lower vegetation albedo,higher soil albedo and small canopy resistance,and wetter soil benefit the oasis area to stay near its initial value,following a moderate SCTD.The convergent trajectories of the initial values in phase space are influenced by the separatrices of the equilibrium points.Higher temperature is an advantage factor for initial values convergent to the oasis expansion solution.
文摘Siwa Oasis,one of Egypts most remote settlements,is also a popular tourist destination thanks to the beautiful salt pools with water that people can float in.Salt is both a blessing and a curse in Siwa.Years ago,people started realizing that there was money to be made in the salt trade,and salt mining operations created the salt lakes that the oasis is now famous for.
基金financially supported by the Tianchi Talents Program of Xinjiang Uygur Autonomous Region(E5358525,2025–2026)the Major Science and Technology Special Project of Xinjiang Uygur Autonomous Region(2024A03009-4)+4 种基金the Third Xinjiang Scientific Expedition Program(2022xjkk010402)the National Key Research and Development Program of China(2022FY202305-06)the Tianshan Talents Program of Xinjiang Uygur Autonomous Region(2022TSYCJU0002)the Outstanding Member of the Youth Innovation Promotion Association of the Chinese Academy of Sciences(20192024–2026).
文摘The diversity and discontinuity of plant communities in the oasis–desert ecotone are largely shaped by variations in groundwater depth,yet the relationships between spatial distribution patterns and ecological niches at a regional scale remain insufficiently understood.This study examined the oasis–desert ecotone in Qira County located in the Tarim Basin of China to investigate the spatial distribution of plant communities and groundwater depth as well as their relationships using an integrated approach that combined remote sensing techniques,field monitoring,and numerical modeling.The results showed that vegetation distribution exhibits marked spatial heterogeneity,with coverage ranked as follows:Tamarix ramosissima>Phragmites australis>Populus euphratica>Alhagi sparsifolia.Numerical simulations indicated that groundwater depths range from 2.00 to 65.00 m below the surface,with the system currently in equilibrium,sustaining an average annual recharge of 1.06×10^(8) m^(3) and an average annual discharge of 1.01×10^(8) m^(3).Groundwater depth strongly influences vegetation composition and structure:Phragmites australis dominates at average groundwater depth of 5.83 m,followed by Populus euphratica at average groundwater depth of 7.05 m.As groundwater depth increases,the community is initially predominated by Tamarix ramosissima(average groundwater depth of 8.35 m),then becomes a mixture of Tamarix ramosissima,Populus euphratica,and Karelinia caspia(average groundwater depth of 10.50 m),and finally transitions to Alhagi sparsifolia(average groundwater depth of 14.30 m).These findings highlight groundwater-dependent ecological thresholds that govern plant community composition and provide a scientific basis for biodiversity conservation,ecosystem stability,and vegetation restoration in the arid oasis–desert ecotone.
基金supported by the Natural Science Foundation of Gansu Province,China(24JRRA733,23JRRA589)the National Natural Science Foundation of China(42377470,42207539)the Light of Western Light Program of Talent Cultivation of Chinese Academy of Sciences(22JR9KA028).
文摘Biological soil crusts(BSCs)play crucial roles in improving soil fertility and promoting plants settlement and reproduction in arid areas.However,the specific effects of BSCs on growth status and nutrient accumulation of plants are still unclear in different arid areas.This study analyzed the effects of three different BSCs treatments(without crust(WC),intact crust(IC),and broken crust(BC))on the growth,inorganic nutrient absorption,and organic solute synthesis of three typical desert plants(Grubovia dasyphylla(Fisch.&C.A.Mey.)Freitag&G.Kadereit,Nitraria tangutorum Bobrov,and Caragana koraiensis Kom.)in the Minqin desert-oasis ecotone of Northwest China.Results showed that the effects of three BSCs treatments on seed emergence and survival of three plants varied with seed types.The IC treatment significantly hindered the emergence and survival of seeds,while the BC treatment was more conducive to seed emergence and survival of plants.BSCs significantly promoted the growth of three plants,but their effects on plant growth varied at different stages of the growth.Briefly,the growth of G.dasyphylla was affected by BSCs in early stage,but the effects on the growth of G.dasyphylla significantly weakened in the middle and late stages.However,the growth of N.tangutorum and C.koraiensis only showed differences at the middle and late stages,with a significant enhancement in growth.Analysis of variance showed that BSCs,plant species,growth period,and their interactions had significant effects on the biomass and root:shoot ratio of three plants.BSC significantly affected the nutrients absorption and organic solute synthesis in plants.Specifically,BSCs significantly promoted nitrogen(N)absorption in plants and increased plant adaptability in N poor desert ecosystems,but had no significant effects on phosphorus(P)absorption.The effects of BSCs on inorganic nutrient absorption and organic solute synthesis in plants varied significantly among different plant species.The results suggest that BSCs have significant effects on the growth and nutrient accumulation of desert plants,which will provide theoretical basis for exploring the effects of BSCs on desert plant diversity,biodiversity conservation,and ecosystem management measures in arid and semi-arid areas.
基金The Foundation for Distinguished Young Scholars of Gansu Province,No.22JR5RA046Key Research Program of Gansu Province,No.23ZDKA0004+2 种基金The Joint Funds of the National Natural Science Foundation of China,No.U22A202690Interdisciplinary Youth Team Project from the Key Laboratory of Cryospheric Science and Frozen Soil Engineering,No.CSFSE-ZQ-2408The Youth Innovation Promotion Association CAS to X.W.,No.2020422。
文摘Carbon fluxes are essential indicators assessing vegetation carbon cycle functions.However,the extent and mechanisms by which climate change and human activities influence the spatiotemporal dynamics of carbon fluxes in arid oasis and non-oasis area remains unclear.Here,we assessed and predicted the future effects of climate change and human activities on carbon fluxes in the Hexi Corridor.The results showed that the annual average gross primary productivity(GPP),net ecosystem productivity(NEP),and ecosystem respiration(Reco)in the Hexi Corridor oasis increased by 263.91 g C·m^(-2)·yr^(-1),118.45 g C·m^(-2)·yr^(-1)and 122.46 g C·m^(-2)·yr^(-1),respectively,due to the expansion of the oasis area by 3424.84 km^(2) caused by human activities from 2000 to 2022.Both oasis and non-oasis arid ecosystems in the Hexi Corridor acted as carbon sinks.Compared to the non-oasis area,the carbon fluxes contributions of oasis area increased,ranging from 10.21%to 13.99%for GPP,8.50%to11.68%for NEP,and 13.34%to 17.13%for Reco.The contribution of the carbon flux from the oasis expansion area to the total carbon flux change in the Hexi Corridor was 30.96%(7.09 Tg C yr^(-1))for GPP,29.57%(3.39 Tg C yr^(-1))for NEP and 32.40%(3.58 Tg C yr^(-1))for Reco.The changes in carbon fluxes in the oasis area were mainly attributed to human activities(oasis expansion)and temperature,whereas non-oasis area was mainly due to climate factors.Moreover,the future increasing trends were observed for GPP(64.99%),NEP(66.29%)and Reco(82.08%)in the Hexi Corridor.This study provides new insights into the regulatory mechanisms of carbon cycle in the arid oasis and non-oasis area.
基金Supported by Central Public-interest Scientific Institution Basal Research Fund of China(BRF090202)~~
文摘Guazhou County of Gansu Province is a typical ecological fragile area lying in the transition area of desert and oasis.The development of its agricultural economy is highly dependent on natural resources and environment.Contradiction of resources characterized agriculture and the fragile ecological environment has become one of the main barriers to log the impact of local agriculture to achieve sustainable development.Aiming at fragile ecological environment and limiting factors of agricultural sustainable development,thoughts and countermeasures of realizing agricultural sustainable development have been proposed.
