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Desert vegetation distribution and species-environment relationships in an oasis-desert ecotone of northwestern China 被引量:4
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作者 ZHAO Peng QU Jianjun +3 位作者 XU Xianying YU Qiushi JIANG Shengxiu ZHAO Heran 《Journal of Arid Land》 SCIE CSCD 2019年第3期461-476,共16页
Environmental heterogeneity significantly affects the structure of ecological communities.Exploring vegetation distribution and its relationship with environmental factors is essential to understanding the abiotic mec... Environmental heterogeneity significantly affects the structure of ecological communities.Exploring vegetation distribution and its relationship with environmental factors is essential to understanding the abiotic mechanism(s)driving vegetation succession,especially in the ecologically fragile areas.In this study,based on the quantitative analysis of plant community and environmental factors in 68 plots at 10 different transects in the Minqin oasis-desert ecotone(ODE)of northwestern China,we investigated desert vegetation distribution and species-environment relationships using multivariate analysis.Two-way indicator species analysis(TWINSPAN),detrended correspondence analysis(DCA),and canonical correspondence analysis(CCA)methods were used.A total of 28 species,belonging to 27 genera in 8 families,were identified.Chenopodiaceae,Zygophyllaceae,Gramineae,and Leguminosae were the largest families.Annual and perennial herbs accounted for 28.60%of the total number of plants,while shrubs(42.90%)were the most dominant.Nitraria tangutorum was the constructive species of the desert plant community.We divided the 68 plots surveyed in this study into 7 community types,according to the results of TWINSPAN.The distribution of these 7 communities in the DCA ordination graph showed that species with a similar ecotype were clustered together.Results of CCA indicated that groundwater was the dominant factor influencing vegetation distribution,while distance between plot and oasis(Dis)and soil electrical conductivity(EC)were the local second-order factors.Our study suggests that optimizing the utilization of groundwater in oases is key to controlling the degradation of desert vegetation.The favorable topographic conditions of sand dunes should be fully utilized for vegetal dune stabilization,and the influence of soil salinity on the selection of afforestation tree species should be considered. 展开更多
关键词 TWINSPAN classification ORDINATION desert plant GROUNDWATER oasis-desert ecotone species-environment relationship Minqin
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Soil properties and herbaceous characteristics in an age sequence of Haloxylon ammodendron plantations in an oasis-desert ecotone of northwestern China 被引量:5
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作者 ZHANG Ke SU Yongzhong +1 位作者 WANG Ting LIU Tingna 《Journal of Arid Land》 SCIE CSCD 2016年第6期960-972,共13页
Haloxylon ammodendron, a typical desert shrub with C4 pathway of photosynthesis, possessing a strong ability to adapt to an extreme drought environment, has a rapid growth rate in sandy lands and is widely used in san... Haloxylon ammodendron, a typical desert shrub with C4 pathway of photosynthesis, possessing a strong ability to adapt to an extreme drought environment, has a rapid growth rate in sandy lands and is widely used in sand-fixing shelter-forest systems in oasis-desert ecotones. To assess the effects of H. ammodendron plantation on the soil, we measured soil properties and herbaceous characteristics along a nearly 40-year chronosequence after H. ammodendron was planted in shifting sand dunes in an oasis-desert ecotone. Results showed that silt and clay fractions increased significantly in the topsoil. The accumulation rates of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP) were faster in the early stages (0-9 years) and slower in the late stages (9-39 years). The soil pH and electrical conductivity (EC) were higher than those in the non-vegetation dunes. Moreover, the soil properties in the topsoil (0-5 cm) showed larger variation scope than those in the deeper soil layers (5-20 cm). The significant relationships of the soil silt+clay content with the chemical properties mainly appeared in the topsoil. The wind erosion susceptibility of the soil, evaluated by erodible fraction (EF), decreased significantly with increasing H. ammodendron plantation age. Additionally, the annual pioneer herb, Agriophyllum squarrosum, was gradually substituted by the annual salt-tolerant herb, Bassia dasyphylla, with increasing plantation age. These results showed beneficial effects of H. ammodendron plantation on improving soil conditions. However, the dynamics of the herbaceous species also reminded us that the long- term effects of H. ammodendron plantation, especially on changes in vegetation composition, still need further evaluation. 展开更多
关键词 Haloxylon ammodendron soil properties HERBACEOUS erodible fraction oasis-desert ecotone
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Quantification of driving factors on NDVI in oasis-desert ecotone using geographical detector method 被引量:4
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作者 ZHANG Yu ZHANG Ke-cun +1 位作者 AN Zhi-shan YU Yan-ping 《Journal of Mountain Science》 SCIE CSCD 2019年第11期2615-2624,共10页
Within oasis-desert ecotone regions,the normalized difference vegetation index(NDVI)is an important parameter for evaluating the growth of vegetation.An accurate quantitative study between NDVI and environmental and a... Within oasis-desert ecotone regions,the normalized difference vegetation index(NDVI)is an important parameter for evaluating the growth of vegetation.An accurate quantitative study between NDVI and environmental and anthropogenic factors is critical for understand the driving factors of vegetation growth in oasis-desert ecotone.In 2016,four periods Landsat 8 OLI_TIRS images,relevant climatological parameters data(air temperature,air relative humidity,wind velocity and accumulated temperature),land cover type data and soil data were selected as proxies.In order to quantify the explanatory power for NDVI spatial and temporal distribution in the southern edge of Dunhuang City and northern side of the Mingsha Mountain,the geographical detector model was used to explain the potential influences of factors versus the spatial distribution of NDVI,and each explanatory variable's relative importance can be calculated.The factor detector results disclose that the spatial distribution of NDVI is primarily dominated by land cover type.The risk detector results show that,high NDVI region is located within woodland.The mean value of NDVI displays an increase and then decrease trend with air temperature increase.With the increase of wind velocity and decrease of air relative humidity,the NDVI value shows a decrease trend.The interactive q values between the two factors are higher than any q value of separated factors.Results also indicate that the strongest interactive effects of NDVI are different in distinct seasons.Consequently,anthropogenic activity is more important than environmental factors on NDVI in oasis-desert ecotone.We also demonstrate that air relative humidity rather than air temperature have played a greater role in NDVI spatial distribution. 展开更多
关键词 Influence factors Normalized DIFFERENCE VEGETATION index GEOGRAPHICAL DETECTOR oasis-desert ecotone
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Species diversity and its relation with soil factors under different site conditions in a desert-oasis ecotone
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作者 TingTing Xie PeiXi Su +2 位作者 ZiJuan Zhou ShanJia Li HaiNa Zhang 《Research in Cold and Arid Regions》 CSCD 2013年第3期331-338,共8页
Vegetation and soil surveys were conducted under different site conditions in 2007-2011 to study species diversity using richness, evenness and diversity indices, in the middle portion of the Heihe River Basin. The re... Vegetation and soil surveys were conducted under different site conditions in 2007-2011 to study species diversity using richness, evenness and diversity indices, in the middle portion of the Heihe River Basin. The relationship between species distribution and soil environmental factors was also studied by Canonical Correspondence Analysis (CCA). Results show that vegetation coverage and species diversity were the highest in the interdune lowland, and the lowest in the mobile dime. Results of the Hill's index (di- versity ordering) shows that species diversity is reduced along decreasing soil water content, and the order of species diversity was interdune lowland, flat slope, fixed dune, semifixed dune and mobile dune. The influence degree of soil factors on vegetation dis- tribution was soil water content 〉 pH 〉 total K 〉 organic matter 〉 available N 〉 total N 〉 available K 〉 total P 〉 saline content 〉 available P. Soil water content and pH were important factors significantly affecting spatial distribution difference of vegetation, the environmental explanation was 98%. 展开更多
关键词 desert-oasis ecotone species diversity soil factor canonical correspondence analysis
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Study on Ecological Landscape Pattern Change of Desert Sewage Discharge Area in Desert-Oasis Ecotone on the Southern Edge of Junggar Basin,Xinjiang
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作者 Xin HAN Li CHEN Shaotang LIU 《Meteorological and Environmental Research》 CAS 2021年第6期7-15,23,共10页
In order to understand the change characteristics of ecological landscape pattern of desert sewage discharge area in the desert-oasis ecotone on the southern edge of Junggar Basin,Xinjiang,based on the remote sensing ... In order to understand the change characteristics of ecological landscape pattern of desert sewage discharge area in the desert-oasis ecotone on the southern edge of Junggar Basin,Xinjiang,based on the remote sensing images of 13 scenes GF1 and GF2 from 2013 to 2019,through image preprocessing,classification interpretation,GIS spatial analysis and landscape pattern index,the conclusions were as follows.From 2013 to 2019,the landscape area of sparse shrub forest land,grassland and saline alkali land increased,while the area of sandy bare land and pond surface increased.The mutual transformation among various types of landscapes was more active,among which the mutual transfer between sandy bare land and sparse shrub forest land was the most frequent.Various landscape dynamics changed significantly with time.All kinds of landscapes and the overall landscape showed the trend of fragmentation,discretization and complexity,and the overall landscape showed the trend of balanced distribution.The above results hoped to provide basic data and technical basis for eco-environmental protection,restoration and treatmen on the southern edge of Junggar Basin,and fill the current research gap. 展开更多
关键词 Landscape pattern index desert-oasis ecotone desert sewage discharge
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Sustainable Development of Agriculture in Northwestern Ecologically Fragile Desert Oasis——A case study of Guazhou County of Gansu Province 被引量:6
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作者 张怀山 乔国华 +1 位作者 王春梅 张茜 《Agricultural Science & Technology》 CAS 2010年第6期175-178,共4页
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
关键词 desert oasis Ecologically fragile area Agricultural sustainable development Guazhou County
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Quantitative Analysis of Land Use Landscape Pattern in Shihezi Desert Oasis
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作者 王玲 吕新 高秀平 《Journal of Landscape Research》 2009年第3期49-54,81,共7页
Based on the land use status map of Shihezi City,the land use landscape map of Shihezi City was made with the support of GIS then many landscape indices were selected to quantitatively analyze the landscape pattern ch... Based on the land use status map of Shihezi City,the land use landscape map of Shihezi City was made with the support of GIS then many landscape indices were selected to quantitatively analyze the landscape pattern characteristics of Shihezi Oasis from three aspects of landscape diversity index,landscape space configuration index and plaque characteristics index. The results showed that the main plaque types of the landscape in Shihezi reclamation area are arable land and water areas,which totally account for 58% of the total area; farmland,gardens,woodland,urban sites,industrial and mining land use were embedded in this oasis landscape in the form of mosaics,and their fractal index was high due to the strong impact of human activities; arable land and mining land distribution was scattered,but marshes and other uncultivated land were relatively concentrated. The dominance degree of the landscape was low because there was no advantageous type in this landscape and all patches distributed equably which was easily to be disturbed so that the whole landscape was unstable. Comprehensively speaking,the landscape in Shihezi region was rather complicate,and its diversity index,fragmentation degree and heterogeneity were high. 展开更多
关键词 Shihezi RECLAMATION area desert oasis LANDSCAPE PATTERN LANDSCAPE index QUANTITATIVE analysis
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Carbon uptake and change in net primary productivity of oasis-desert ecosystem in arid western China with remote sensing technique 被引量:4
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作者 ZHANG Jie PAN Xiaoling +2 位作者 GAO Zhiqiang SHI Qingdong LV Guanghui 《Journal of Geographical Sciences》 SCIE CSCD 2006年第3期315-325,共11页
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
关键词 add western area oasis desert spectral mixture analysis NPP-PEM net primary productivity Kaxger
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Wind and sand control by an oasis protective system: a case from the southeastern edge of the Tengger Desert, China 被引量:2
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作者 XIE Yun-hu DANG Xiao-hong +10 位作者 MENG Zhong-ju JIANG Hong-tao LI Xiao-jia ZHOU Rui-ping ZHOU Dan-dan LIU Xiao-xi DING Jing WU Xue-qin WANG Yu-hao HAI Chun-xing WANG Ji 《Journal of Mountain Science》 SCIE CSCD 2019年第11期2548-2561,共14页
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
关键词 oasis protective SYSTEM Windproof effect Sediment transport WIND erosion intensity Tengger desert desertIFICATION
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PHENOMENON OF ESTABLISHING COENOSIUM IN DESERT AND THE ECOLOGICAL RESTORATION IN THE AREA AROUND THE OASIS 被引量:2
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作者 Huang Pei you Department of Biology, Xinjiang Universty, Urumqi 830046 《干旱区资源与环境》 CSCD 1993年第Z1期299-301,共3页
The area around the oasis, lying between the oasis and the natural desert and encirclesthe oasis is different from ecotone of the oasis and the desert, because it is not the trans-forming area betwen them, but it is e... The area around the oasis, lying between the oasis and the natural desert and encirclesthe oasis is different from ecotone of the oasis and the desert, because it is not the trans-forming area betwen them, but it is ecological rift valley or ecological burst zone. The oasisbase will be shaked and the nature desert will be degenerative too. It is the crux of the envi- 展开更多
关键词 desert VEGETATION Coenosium ESTABLISHMENT oasis Ecologic RESTORATION
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Evapotranspiration of an oasis-desert transition zone in the middle stream of Heihe River, Northwest China 被引量:18
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作者 LiWen ZHAO WenZhi ZHAO 《Journal of Arid Land》 SCIE CSCD 2014年第5期529-539,共11页
As a main component in water balance, evapotranspiration is of great importance for water saving and irrigation-measure making, especially in arid or semiarid regions. Although studies of evapotranspiration have been ... As a main component in water balance, evapotranspiration is of great importance for water saving and irrigation-measure making, especially in arid or semiarid regions. Although studies of evapotranspiration have been conducted for a long time, studies concentrated on oasis-desert transition zone are very limited. On the basis of the meteorological data and other parameters(e.g. leaf area index(LAI)) of an oasis-desert transition zone in the middle stream of Heihe River from 2005 to 2011, this paper calculated both reference(ET0) and actual evapotranspiration(ETc) using FAO56 Penman-Monteith and Penman-Monteith models, respectively. In combination with pan evaporation(Ep) measured by E601 pan evaporator, four aspects were analyzed:(1) ET0 was firstly verified by Ep;(2) Characteristics of ET0 and ETc were compared, while the influencing factors were also analyzed;(3) Since meteorological data are often unavailable for estimating ET0 through FAO56 Penman-Monteith model in this region, pan evaporation coefficient(Kp) is very important when using observed Ep to predict ET0. Under this circumstance, an empirical formula of Kp was put forward for this region;(4) Crop coefficient(Kc), an important index to reflect evapotranspiration, was also analyzed. Results show that mean annual values of ET0 and ETc were 840 and 221 mm, respectively. On the daily bases, ET0 and ETc were 2.3 and 0.6 mm/d, respectively. The annual tendency of ET0 and ETc was very similar, but their amplitude was obviously different. The differences among ET0 and ETc were mainly attributed to the different meteorological variables and leaf area index. The calculated Kc was about 0.25 and showed little variation during the growing season, indicating that available water(e.g. precipitation and irrigation) of about 221 mm/a was required to keep the water balance in this region. The results provide an comprehensive analysis of evapotranspiration for an oasis-desert transition zone in the middle stream of Heihe River, which was seldom reported before. 展开更多
关键词 EVAPOTRANSPIRATION pan evaporation water requirement arid region oasis-desert transition zone
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How changes of groundwater level affect the desert riparian forest ecosystem in the Ejina Oasis,Northwest China 被引量:1
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作者 HaiYang Xi JingTian Zhang +3 位作者 Qi Feng Lu Zhang JianHua Si TengFei Yu 《Research in Cold and Arid Regions》 CSCD 2019年第1期62-80,共19页
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
关键词 groundwater CHANGES desert RIPARIAN forest EJINA oasis WAVES leaf area index(LAI) water budgets
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Effects of an oasis protective system on aeolian sediment deposition:a case study from Gelintan oasis,southeastern edge of the Tengger Desert,China
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作者 DING Jing XIE Yun-hu +6 位作者 LI Xiao-jia JIANG Hong-tao WANG Ji LIU Xiao-xi WU Xue-qin WANG Yu-hao HAI Chun-xing 《Journal of Mountain Science》 SCIE CSCD 2020年第8期2023-2034,共12页
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
关键词 Aeolian sediment deposition desert oasis ecotone Grain size characteristics oasis protective system Tengger desert
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Oasis in the Desert
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作者 CHEN RINONG 《China Today》 1996年第9期46-48,共3页
OasisintheDesertByCHENRINONGAChinesemantravelstoAmerica'sSouthwest,andcomesawaywithadeeperunderstanding.Atth... OasisintheDesertByCHENRINONGAChinesemantravelstoAmerica'sSouthwest,andcomesawaywithadeeperunderstanding.Atthecountyfair.TUSCO... 展开更多
关键词 oasis in the desert
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Numerical Simulation of the Critical Scale of Oasis Maintenance and Development in the Arid Regions of Northwest China 被引量:12
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作者 高艳红 陈玉春 吕世华 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2004年第1期113-124,共12页
Oasis is a special geographic landscape among the vast desert/Gobi in Northwest China (NWC). The surface sensitive heat flux and latent heat flux at Zhangye Oasis during 1 to 11 August 1991 are simulated using the NCA... Oasis is a special geographic landscape among the vast desert/Gobi in Northwest China (NWC). The surface sensitive heat flux and latent heat flux at Zhangye Oasis during 1 to 11 August 1991 are simulated using the NCAR nonhydrostatic mesoscale model MM5 Version 3. The horizontal grid resolution is set as 1km. By comparing the simulation results with HEIFE observations, it is proved that the model can be used to simulate the surface energy and water mass exchange of arid and semiarid regions in NWC. Based on the above results, the influence of different oasis scales on the local atmospheric field near the ground surface, and the critical scale of oasis maintenance, in NWC are studied dynamically. The following conclusion is obtained: the local thermal circulation between the oasis and the desert/Gobi is formed in the oasis downstream if the oasis scale is larger than 4 km. This local thermal circulation between the oasis and the desert adjacent to the oasis helps to conserve water vapor over the oasis. At the same time, it transfers the abundant water vapor from the oasis into the desert/Gobi near to the oasis to supply relatively plentiful water vapor for desert crops to grow on the fringe of the oasis. So, it is advantageous for oasis extension. However, if the scale of the oasis is smaller than 4 km, it is not easy for the local thermal circulation between the oasis and the desert/Gobi to take shape. This study provides a new standpoint for oasis maintenance and development. 展开更多
关键词 MM5 oasis desert/Gobi critical scale local thermal circulation
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On a Simple Dynamics Model of Interaction between Oasis and Climate 被引量:5
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作者 吴凌云 巢纪平 +1 位作者 符淙斌 潘晓玲 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2003年第5期775-780,共6页
This paper constructs a coupled system of oasis and atmosphere based on an oasis evolvement model by adding atmospheric motion to discuss the problem of oasis evolvement and its effects on regional climate. The result... This paper constructs a coupled system of oasis and atmosphere based on an oasis evolvement model by adding atmospheric motion to discuss the problem of oasis evolvement and its effects on regional climate. The results indicate that the range and scope of the negative temperature anomalies become larger when the oasis cover fraction increases. Correspondingly, the positive temperature anomalies becomes smaller in the desert no matter in summer or spring. And the variability is more obvious in summer than in spring. So it may be concluded that the oasis not only maintains and develops itself but also develops partial air over the desert into an oasis climate. 展开更多
关键词 oasis desert temperature anomalies
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Microclimatic characteristics of the Heihe oasis in the hyperarid zone of China 被引量:4
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作者 FENG Qi SI Jianhua ZHANG Yanwu YAO Jiming LIU Wei SU Yonghong 《Journal of Geographical Sciences》 SCIE CSCD 2006年第1期34-44,共11页
The microclimate of a desert oasis in hyperarid zone of China was monitored using micrometeorological methods and compared with those of areas adjacent to forested land. Differences in ground-level photosynthetically ... The microclimate of a desert oasis in hyperarid zone of China was monitored using micrometeorological methods and compared with those of areas adjacent to forested land. Differences in ground-level photosynthetically active radiation (PAR) on clear, cloudy and dust storm days and their subtending causes are analysed and discussed. Desert oases serve the ecological functions of altering solar radiation, adjusting near-ground and land surface temperatures, reducing soil temperature differences, lowering wind velocity, and increasing soil and atmospheric humidity. The total solar radiation in the interior of the oasis was roughly half of that outside a forest canopy. During the growing season, air temperatures in Populus euphratica Oliv. (poplar) and Tamarix ramosissima Ledeb. (tamarisk) forests were 1.62℃ and 0.83 ℃ lower respectively than those in the areas around the forests. Furthermore, the miler the forest cover, the greater the temperature drops; air temperatures in the upper storey were greater than those in the lower storey, i.e., air temperature rose with increasing height. Over the growing season, the relative humidities of the air in the poplar and tamarisk forests were 8.5% and 4.2% higher respectively than those in areas around the forests. Mean wind velocity in poplar-forested lands was 0.33 m·s^-1, 2.31 m·s^-1 lower than that in the surrounding area. During dust storm days the PAR was significantly lower than that on cloudy or clear days, when it was high and varied in an irregular manner. 展开更多
关键词 hyperarid zone desert oasis photosynthetically active radiation (PAR) MICROCLIMATE
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Evaluation of Waterlogged Areas in El-Farafra Oasis, Egypt
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作者 Ahmed Ibrahim Mohamed El-Sayed Ewis Omran 《Open Journal of Soil Science》 2019年第11期232-242,共11页
A geographic information system (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographical data. The key word to this technology is Geography—this means that some... A geographic information system (GIS) is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographical data. The key word to this technology is Geography—this means that some portion of the data is spatial. In other words, data that is in some way referenced to locations on the earth. The goal of this study is to evaluate how precisely waterlogging can be identified from medium-goals satellite pictures utilizing EWIS list. The point is to distinguish and mapping of the waterlogged territories in the piece of Farafra Desert Oasis of Egypt. To complete this identification, Landsat-8 symbolism and geographical sheets (1:50,000) have been utilized and handling through Envi 5.3 and Circular segment GIS 10.3, with field perceptions. The waterlogged regions have positive change (+), anyway grounds have negative change (&minus;). Land has been diminished while water bodies have upward pattern. These waterlogged zones have been mapped at a general exactness of 99.22%. The primary explanations behind this descending rate are mostly improvement and anthropogenic mediations. The investigation shows utility of reconciliation of remote detecting and GIS systems for evaluation of waterlogged territories especially in districts where waterlogging conditions happen both because of over the top water system and poor waste. This investigation is recommended that an appraisal of water logging utilizing remotely detected information ought to be completed at customary interims. 展开更多
关键词 Waterlogged Farafra desert oasis EGYPT Landsat-8 GIS
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Carbon assimilation characteristics of plants in oasis-desert ecotone and their response to CO_2 enrichment 被引量:6
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作者 SU Peixi CHEN Huaishun AN Lizhe LIU Xinmin 《Science China Earth Sciences》 SCIE EI CAS 2004年第z1期39-49,共11页
Six species of more than 20-year-old desert woody plants in the oasis-desert ecotone were selected for study. The results showed that: (1) in different growing seasons δ13C values of assimilating organ varied between... Six species of more than 20-year-old desert woody plants in the oasis-desert ecotone were selected for study. The results showed that: (1) in different growing seasons δ13C values of assimilating organ varied between -14‰ and -16‰ for Haloxylon ammodendron (HA),-14‰-15‰ for Calligonum mongolicum (CM) and-25‰- -28‰ for Caragana korshinskii(CK), Nitraria sphaerocarpa (NS) and Hedysarum scoparium (HS). (2) The net photosynthetic rate (Pn) of HA and CM was significantly higher than those of the other species. With the decrease in Pn for the six species, their intercellular CO2 concentration increased, but stomatal limitation value decreased under the intensive light. At the same time, the photochemical efficiency of PS II dropped to different degrees. (3) The CO2 enrichment experiment demonstrated that, Pn of HA and CM increased to different extent under 450 umol/mol, but their Pn reduced or approximated to the current condition under 650 umol/mol. Under 450 umol/mol the efficiency for solar energy utilization of CK and HS significantly reduced and under 650 umol/mol their respiration rate exceeded photosynthesis rate. It can be concluded that HA and CM have some function of pathway for C4, but the other three species have the function for C3. The decline in their Pn is mainly caused by non-stomatal factors. HA, CM, CKand HS exhibited photoinhibition, which disappeared in a short time. This is a kind of positive readjustment to adapting to the desert environment. HA and CM can adapt to the high CO2 environment, but CK and HS cannot. With the rise in atmospheric CO2 concentration and climate warming, the latter two species in the oasis-desert ecotone may be gradually degraded or even disappear. 展开更多
关键词 oasis-desert ecotone CARBON assimilation stable CARBON ISOTOPE ratio photoinhibition CO2 enrichment.
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荒漠-绿洲过渡带NDVI演变及影响因子相关性分析 被引量:1
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作者 赵琪 王琳 +3 位作者 潘世兵 熊伟 左芸 达朝吉 《中国水利水电科学研究院学报(中英文)》 北大核心 2024年第3期239-249,共11页
荒漠-绿洲过渡带是绿洲与荒漠相互转化过程中表现最活跃的地区,具有防止荒漠扩张、维持绿洲生态安全等重要的生态功能。本研究以民勤县为研究区域,根据绿洲外围归一化差异植被指数(Normalized difference vegetation index,NDVI)的变化... 荒漠-绿洲过渡带是绿洲与荒漠相互转化过程中表现最活跃的地区,具有防止荒漠扩张、维持绿洲生态安全等重要的生态功能。本研究以民勤县为研究区域,根据绿洲外围归一化差异植被指数(Normalized difference vegetation index,NDVI)的变化规律,确定民勤荒漠-绿洲过渡带的范围;利用2000—2020年内最大NDVI数据及降水、温度、日照时数、土壤水分影响因子,在像元尺度采用偏相关及多元相关分析方法,研究过渡带NDVI变化趋势及影响因子相关性分析。结果表明,绿洲边界外5000 m范围为民勤荒漠-绿洲过渡带范围,其中绿洲外0~300 m为过渡带核心区,300~2000 m为过渡带交错区,2000~5000 m范围为过渡带缓冲区。自2000年以来,过渡带区域NDVI整体呈增加趋势,其中,明显改善和稳定不变的面积占比较高,分别为47.8%和42.2%,其他占比较小,严重退化区域主要在靠近绿洲的过渡带核心区。降水增加对过渡带南部地带性植被的改善起主导作用,温度的上升对过渡带东部及西北部NDVI改善的促进作用更明显,日照时数的增加对过渡带西部及东南部NDVI改善的促进作用更大,土壤水分的增加对过渡带整体NDVI的改善均具有促进作用。土壤水分和降水是促进过渡带NDVI改善的主要因子。 展开更多
关键词 荒漠-绿洲过渡带 NDVI 影响因子 空间相关性
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