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Quantifying the impacts of soil water stress on the winter wheat growth in an arid region,Xinjiang

Journal of Arid Land 2009年第1期1卷 34-42页

作者： Yilihm.Yimam key laboratory of oasis ecology and Desert Environment Xinjiang Institute of Ecology and Geography

Wheat growth in response to soil water deficit play an important role in yield stability. A field experiment was conducted for winter wheat (Triticum aestivum L.) during the period of 2002-2005 to evaluate the effects of limited irrigation on winter wheat growth. 80%, 70%, 60%, 50% and 40% of field capacity was applied at different stages of crop growth. Photosynthetic characteristics of winter wheat, such as photosynthesis rate, transpiration rate, stomatal conductance, photosynthetically active radiation, and soil water content, root and shoot dry mass accumulation were measured, and the root water uptake and water balance in different layer were calculated. Based on the theory of unsaturated dynamic, a one-dimensional numerical model was developed to simulate the effect of soil water movement on winter wheat growth using Hydrus-1 D. The soil water content of stratified soil in the experimental plot was calculated under deficit irrigation. The results showed that, in different growing periods, evapotranspiration, grain yield, biomass, root water uptake, water use efficiency, and photosynthetic characteristics depended on the controlled ranges of soil water content. Grain yield response to irrigation varied considerably due to differences in soil moisture contents and irrigation scheduling between seasons. Evapotranspiration was largest in the high soil moisture treatment, and so was the biomass, but this treatment did not produce the highest grain yield and root water uptake was relatively low. Maximum depth of root water uptake is from the upper 80 cm in soil profile in jointing stage and dropped rapidly upper 40 cm after heading stage, and the velocity of root water uptake in latter stage was less than that in middle stage. The effect of limited irrigation treatment on photosynthesis was complex owing to microclimate. But root water uptake increased linearly with harvest yield and improvement in the latter gave better root water uptake under limited irrigation c

关键词： soil water water stress deficit irrigation numerical simulation photosynthesis arid region

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What makes Haloxylon persicum grow on sand dunes while H. ammodendron grow on interdune lowlands: a proof from reciprocal transplant experiments

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Journal of Arid Land 2014年第5期6卷 581-591页

作者： GuiQing XU DanDan YU JiangBo XIE LiSong TANG Yan LI State key laboratory of Desert and oasis ecology Xinjiang Institute of Ecology and GeographyChinese Academy of Sciences

Determining the mechanisms underlying the spatial distribution of plant species is one of the central themes in biogeography and ecology. However, we are still far from gaining a full understanding of the autecological processes needed to unravel species distribution patterns. In the current study, by comparing seedling recruitment, seedling morphological performance and biomass allocation of two Haloxylon species, we try to identify the causes of the dune/interdune distribution pattern of these two species. Our results show the soil on the dune had less nutrients but was less saline than that of the interdune; with prolonged summer drought, soil water availability was lower on the dune than on the interdune. Both species had higher densities of seedlings at every stage of recruitment in their native habitat than the adjacent habitat. The contrasting different adaptation to nutrients, salinity and soil water conditions in the seedling recruitment stage strongly determined the distribution patterns of the two species on the dune/interdune. Haloxylon persicum on the dunes had lower total dry biomass, shoot and root dry biomass, but allocated a higher percentage of its biomass to roots and possessed a higher specific root length and specific root area by phenotypic traits specialization than that of Haloxylon ammodendron on the interdune. All of these allowed H. persicum to be more adapted to water stress and nutrient shortage. The differences in morphology and allocation facilitated the ability of these two species to persist in their own environments.

关键词： Haloxylon seedling recruitment root distribution biomass allocation species distribution

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oasis cold island effect and its influence on air temperature: a case study of Tarim Basin, Northwest China

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Journal of Arid Land 2016年第2期8卷 172-183页

作者： HAO Xingming LI Weihong State key laboratory of Desert and oasis ecology Xinjiang Institute of Ecology and GeographyChinese Academy of Sciences

oasis effect can improve the regional climate and habitability of an arid region. In this study, we explored the cold island effects of oases distributed along the edge of Tarim Basin by analyzing the oasis cold island effect （OCIE） intensity, spatial-temporal variation of OCIE, factors influencing the OCIE and impacts of OCIE on air temperature using geographical statistics and GIS methods based on the MODIS land surface temperature, land use/cover change （LUCC） and observed air temperature data. Results showed that all the oases in the Tarim Basin exhibited cold island effects, with the OCIE intensity highest in summer （-9.08℃）, followed by autumn （-4.24℃） and spring （-3.85℃）. The total area of oasis cold island （OCI） and the comprehensive OCIE index showed the same seasonal change trend as the OCIE intensity. However, the changing trends in areas of OCI with strong, medium and weak OCIEs were inconsistent across different seasons. Farmland and water areas were found to be the key contributors that affected the OCIE, and the area and aggregation metrics of these two land use/cover types directly contributed to the OCIE. By contrast, natural vegetation, such as forest and grassland, almost had no contribution to the OCIE. Simulation of observed air temperature data showed that if farmland is replaced by forest or grassland in the oasis, the mean, maximum and minimum air temperatures will increase significantly. This heating effect will be higher in summer （reaching 1.14℃ to 2.08℃） and lower in spring and autumn. Moreover, the heating effect of farmland being replaced by forest will be higher than that of farmland being replaced by grassland. These results can provide a basis for understanding the cold island effect of oases in arid regions.

关键词： oasis cold island effect comprehensive oasis cold island effect index landscape index oasis evolution arid environment

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Impacts of Global Warming Perturbation on Water Resources in Arid Zone: Case Study of Kaidu River Basin in Northwest China

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Journal of Mountain Science 2011年第5期8卷 704-710页

作者： MUPENZI Jean de la Paix State key laboratory of Desert and oasis ecology Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences

The main goal of this study was to assess the long-term impacts of global warming perturbation on water resources of the Kaidu River Basin in Northwest China. Temperature, precipitation and hydrology data during the past 29 years from 1979 to 2007 were collected and analyzed using parametric and non-parametric methods, the connection between temperature and precipitation by the combination of grey correlation analysis method and the hypothesis testing for trend of climate change. The results show a high increase in temperature in the study area as well as an extreme and highly variable hydrological regime in this region, where flash floods can exceed the total runoff from a sequence of years. These variations may be due to the geographical location of the Kaidu River Basin in arid zone. It also reveals that precipitation has a much greater impact on stream flow than that of temperature. The development of new approaches was proposed as responses to climate change in this arid region.

关键词： Global warming Kaidu River Temperature Precipitations Stream flow

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Localized salt accumulation: the main reason for cotton root length decrease during advanced growth stages under drip irrigation with mulch film in a saline soil

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Journal of Arid Land 2014年第3期6卷 361-370页

作者： WenXuan MAI ChangYan TIAN Li LI State key laboratory of Desert and oasis ecology Xinjiang Institute of Ecology and GeographyChinese Academy of Sciences

High salinity in soil can prevent root growth of most plants. To investigate soil salinity dynamics under drip irrigation with mulch film （DI） and its effects on cotton root length, we conducted field experiments in saline soil based on a monolith method using flooding irrigation with mulch film （FI） as a control at the Korla Experimental Station of the Xinjiang Academy of Agricultural Sciences, China in 2009 and 2010. The results showed that the total root length decreased 120 days after sowing （DAS） under DI, and was mainly centered in the 0-30 cm soil layer and at distances of 30-70 cm from the drip-lines. There was almost complete overlap in the area of root length decline and salt accumulation. In the soil depth of 0-30 cm and at distances of 30-70 cm from the drip-lines at 110 to 160 DAS in 2009 and 171 DAS in 2010, the electrical conductivity （EC） in all soil samples was at least 3 mS/cm and in some cases exceeded 5 mS/cm under DI treatment. However, EC barely exceeded 3 mS/cm and no reduction in root length was observed under FI treatment. Correlation analysis of soil EC and root length density indicated that the root length declined when the soil EC exceeded 2.8 mS/cm. The main reason for the decrease of root length in cotton under DI was localized accumulation of salinity.

关键词： cotton drip irrigation under mulch film flooding irrigation under mulch film root salinity

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Study on Soil Salinization Information in Arid Region Using Remote Sensing Technique

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Agricultural Sciences in China 2011年第3期10卷 404-411页

作者： Tashpolat Tiyip key laboratory of oasis ecology Ministry of Education/College of Resources and Environmental Science Xinjiang University

Extracting information about saline soils from remote sensing data is useful, particularly given the environmental significance and changing nature of these areas in arid environments. One interesting case study to consider is the delta oasis of the Weigan and Kuqa rivers, China, which was studied using a Landsat Enhanced Thematic Mapper Plus （ETM＋） image collected in August 2001. In recent years, decision tree classifiers have been successfully used for land cover classification from remote sensing data. Principal component analysis （PCA） is a popular data reduction technique used to help build a decision tree; it reduces complexity and can help the classification precision of a decision tree to be improved. A decision tree approach was used to determine the key variables to be used for classification and ultimately extract salinized soil from other cover and soil types within the study area. According to the research, the third principal component （PC3） is an effective variable in the decision tree classification for salinized soil information extraction. The research demonstrated that the PC3 was the best band to identify areas of severely salinized soil; the blue spectral band from the ETM＋ sensor （TM1） was the best band to identify salinized soil with the salt-tolerant vegetation of tamarisk （Tamarix chinensis Lour）; and areas comprising mixed water bodies and vegetation can be identified using the spectral indices MNDWI （modified normalized difference water index） and NDVI （normalized difference vegetation index）. Based upon this analysis, a decision tree classifier was applied to classify landcover types with different levels of soil saline. The results were checked using a statistical accuracy assessment. The overall accuracy of the classification was 94.80%, which suggested that the decision tree model is a simple and effective method with relatively high precision.

关键词： soil salinization information arid region remote sensing

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Dielectric properties of saline soil based on a modified Dobson dielectric model

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Journal of Arid Land 2015年第5期7卷 696-705页

作者： Nigara TASHPOLAT DING Jianli YU Danlin key laboratory of oasis ecology Xinjiang University Earth and Environmental Studies Montclair State University

Soil salinization is a major concern for agricultural development in arid areas. In this paper, a modified Dobson dielectric model was applied to simulate the dielectric constant of saline soil in the Ugan-Kuqa river delta oasis of Xinjiang Uygur autonomous region, northwestern China. The model performance was examined through analyzing the influences of its parameters on the soil dielectric constant and the relationship between radar back- scattering coefficient and the dielectric constant of saline soil. The results of the study indicate that：（1） The real part of the soil dielectric constant is affected by soil water content at low radar frequencies; the imaginary part is closely related with both the soil water content and soil salt content. （2） The soil water and salt contents are related with the coefficient of dialectical loss, which is consistent with the natural conditions of saline soil in arid areas and provides valuable references for the study of soil dielectric properties. （3） The changes of soil water content and soil salt content have instant influences on the dielectric constant of saline soil. Subsequently, the radar backscattering coefficient is affected to respond to the dielectric constant of saline soil. The radar backscattering coefficient is most responsible to the radar＇s cross polarization pattern with a correlation coefficient of R2=0.75. This study provides a potential method to monitor soil salinization and soil water content by using a soil dielectric model and radar tech- niques.

关键词： saline soil dielectric constant dielectric constant model backscattering coefficient Radarsat-2 images

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Effects of soil moisture on cotton root length density and yield under drip irrigation with plastic mulch in Aksu oasis farmland

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Journal of Arid Land 2010年第4期2卷 243-249页

作者： Yilihamu Yimamu key laboratory of oasis ecology and Desert Environment Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences

Effects of soil moisture on cotton root length density (total root length per unit soil volume) and yield under drip irrigation with plastic mulch were studied through field experiments. The results indicate that spatial distributions of root length density of cotton under various water treatments were basically similar. Horizontally, both root length densities of cotton in wide and narrow rows were similar, and higher than that between mulches. Vertically, root length density of cotton decreased with increasing soil depth. The distribution of root length density is different under different irrigation treatments. In conditions of over-irrigation, the root length density of cotton between mulches would increase. However, it would decrease in both the wide rows and narrow rows. The mean root length density of cotton increased with increasing irrigation water. Water stress caused the root length density to increase in lower soil layers. There is a significant correlation between root length density and yields of cotton at the flower-boll and wadding stages. The regression between irrigation amount and yield of cotton can be expressed as y = -0.0026x2+18.015x-24845 (R2 = 0.959). It showed that the irrigation volume of 3,464.4 m3/hm2 led to op-timal root length density. The yield of cotton was 6,360 .8 kg/hm2 under that amount of irrigation.

关键词： drip irrigation under plastic mulch soil moisture cotton root length density

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Monitoring variations of inland lakes in the arid region of Central Asia

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Frontiers of Earth Science 2012年第2期6卷 147-156页

作者： Jie BAI Xi CHEN Liao YANG Hui FANG State key laboratory of Desert and oasis ecology Xinjiang Institute of Ecology and GeographyChinese Academy of SciencesUrumqi 830011China

Inland lakes are the major surface water resource in the arid regions of Central Asia. Therefore, the surface area changes in inland lakes have been a sensitive indicator of climate changes and human activ- ities, and have often been the focus of ecological and environmental research. This study aimed to monitor the changes in surface area of nine major lakes over a 32-year period. The water body was extracted from MSS images from the mid-1970s, TM images from the early 1990s, ETM ＋ images in the late 1990s, and TM images in 2007. The results indicated that the total surface area of these nine lakes had decreased over time to 50.38% of the area, from 91402.06km^2 in 1975 to 46049.23 km^2 in 2007. As the surface area of lakes in the western part of Central Asia was larger than that in the eastern part, the shrinking trend of lake area was more significant in the west than in the east. There was a varied reduction of closed lakes in flat regions. The most substantial decrease was in the surface area of closed lakes in flat regions. Most significantly, the area of the Aral Sea was reduced by 75.7% from its original area in 1975. The area of alpine lakes remained relatively stable; the change in surface area was less than 0.7% during the period 1975-2007. The area change in opened lakes with outlets was notably different from the other two types. The area of Zaysan had increased sharply by 5.85%, and that of Bosten had decreased by 9.1%. Sasykkol had hardly any changes in this period. Due to global climate wanning, vapor transfer to the south via westerly winds had been blocked, resulting in a decrease of much-needed precipitation in the western parts of Turkmenistan, Uzbekistan, and Kazakhstan between 1970 and 2000. The decrease in precipitation and the increase in water consumption for agricultural irrigation resulted in the decrease of fiver runoff. Consequently, thearea of inland lakes in Central Asia shrank over the past 32 years.

关键词： Central Asia inland lake area change climatechange

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Arbuscular mycorrhizal fungi infection in desert riparian forest and its environmental implications: A case study in the lower reach of Tarim River

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Progress in Natural Science:Materials International 2008年第8期18卷 983-991页

作者： Yuhai Yang, Yaning Chen *, Weihong Li key laboratory of oasis ecology and Desert Environment, Xinjiang Institute of ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China key laboratory of oasis ecology and Desert Environment Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi 830011 China

This study was conducted on the desert riparian forest along the lower reach of the inland Tarim River, which is located in the arid region of Northwest *** plant species in 10 families were collected from five monitoring sections,and examined for the infection of arbuscular mycorrhizal fungi (AMF). The impact of different soil factors on AMF infection rate and intensity was compared using the principal component analysis (PCA) method. The results indicate that 11 species are AM and only 4 are non-AM plants. The estimated capacity of AMF infection depends on families of plants and also the parameters (infection rate, infection intensity, fungal spore density) used. The density of fungal spores was relatively higher in Phragmites communis and Populus euphratica in Graminaceae and Salicaceae families, *** infection rate was above 50%in all the AM plants,except Calligonum *** highest infection rate appeared in Alhagi sparsifolia (97%) and Glycyrrhiza inflata (92%). However, when compared by AMF infection intensity, Tamarix spp. became the top one, followed by Alhagi sparsifolia, and Glycyrrhiza inflata was in the middle range of all the species. The PCA has identified that soil total salt, moisture, organic matter, total nitrogen, total P, available K and pH were closely associated with the AMF infection.

关键词： Arbuscular mycorrhiza Infection Ecological restoration Desert riparian forest Soil

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