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Tracking desertification on the Mongolian steppe through NDVI and field-survey data

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International Journal of Digital Earth 2011年第1期4卷 50-64页

作者： Troy Sternberg Renchin Tsolmon Nicholas Middleton David Thomas School of Geography Oxford UniversitySouth Parks RoadOxford OX13QYUK UNESCO Remote Sensing Lab National University of MongoliaMain Building 1Bag Toru AvenueUlaan BaatarMongolia

Changing environmental and socio-economic conditions make land degradation,a major concern in Central and East *** satellite imagery,particularly Normalized Difference Vegetation Index(NDVI)data,has proved an effective tool for monitoring land cover *** study examines 33 grassland water points using vegetation field studies and remote sensing techniques to track desertification on the Mongolian *** established a significant correlation between same-year field observation(line transects)and NDVI data,enabling an historical land cover perspective to be developed from 1998 to *** show variable land cover patterns in Mongolia with a 16%decrease in plant density over the time *** in cover identified by NDVI suggests degradation;however,continued annual fluctuation indicates desertificationirreversible land cover changehas not ***,in situ data documenting greater cover near water points implies livestock overgrazing is not causing degradation at water *** combination of the two research methodsremote sensing and field surveysstrengthen findings and provide an effective way to track desertification in dryland regions.

关键词： desertification NDVI piosphere Mongolia overgrazing digital earth

Pyrosequencing of nirS gene revealed spatial variation of denitrifying bacterial assemblages in response to wetland desertification at Tibet plateau

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Journal of Mountain Science 2019年第5期16卷 1121-1134页

作者： GU Yun-fu LIU Ting BAI Yan XIANG Quan-ju ZHANG Xiao-ping CHEN Qiang Department of Microbiology College of Resource Science and Technology Sichuan Agricultural University

Amplicon sequencing of functional genes is a powerful technique to explore the diversity and abundance of microbes involved in biogeochemical processes. One such key process, denitrification, is of particular importance because it can transform nitrate(NO3-) to N2 gas that is released to the atmosphere. In nitrogen limited alpine wetlands, assessing bacterial denitrification under the stress of wetland desertification is fundamental to understand nutrients, especially nitrogen cycling in alpine wetlands, and thus imperative for the maintenance of healthy alpine wetland ecosystems. We applied amplicon sequencing of the nirS gene to analyze the response of denitrifying bacterial community to alpine wetland desertification in Zoige, China. Raw reads were processed for quality, translated with frameshift correction, and a total of 95,316 nirS gene sequences were used for rarefaction analysis, and 1011 OTUs were detected and used in downstream analysis. Compared to the pristine swamp soil, edaphic parameters including water content, organic carbon, total nitrogen, total phosphorous, available nitrogen, available phosphorous and potential denitrification rate were significantly decreased in the moderately degraded meadow soil and in severely degraded sandy soil. Diversity of the soil nirS-type denitrifying bacteria communities increased along the Zoige wetland desertification, and Proteobacteria and Chloroflexi were the dominant denitrifying bacterial species. Genus Cupriavidus(formerly Wautersia), Azoarcus, Azospira, Thiothrix, and Rhizobiales were significantly(Pdesertification succession. Soil available phosphorous was the key determinant of the composition of the nirS gene containing denitrifying bacterial communities. The proportion of depleted taxa increased along the desertification of the Zoige wetland, suggesting that wetland desertification created specific physicochemical conditions that decreased the microhabitats for bacteria

关键词： Wetland desertification Amplicon sequencing nirS bacteria Differential abundance analysis

Classification of desertification on the North Bank of Qinghai Lake

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Computers, Materials & Continua 2022年第7期72卷 695-711页

作者： Wenzheng Yu Xin Yao Li Shao Jing Liu Yanbo Shen Hanxiaoya Zhang School of Geographical Sciences Nanjing University of Information Science&TechnologyNanjing210044China School of Environmental Science&Engineering Nanjing University of Information Science&TechnologyNanjing210044China Public Meteorological Service Center China Meteorological AdministrationBeijing100081China Center for Wind and Solar Energy Resources China Meteorological AdministrationBeijing100081China Faculty of Science The University of Auckland1010New Zealand

In this paper,RS,GIS and GPS technologies are used to interpret the remote sensing images of the north shore of Qinghai Lake from 1987 to 2014 according to the inversion results of vegetation coverage(FVC),albedo,land surface temperature(LST),soil moisture(WET)and other major parameters after image preprocessing,such as radiometric correction,geometric correction and atmospheric *** this basis,the decision tree classification method based on landsat8 remote sensing image is used to classify the desertification land in this area,and the development and change of desertification in this period are *** results show that the fluctuation of desertification land area in this area increased during the study period,but from 2003 to 2014,the land area of mild desertification,moderate desertification and severe desertification landwere respectively decreased 0.92,145.89 and 29.39 km2,while the area of serious desertification land still has a slow increasing *** the driving force of desertification change trend in this area is caused by human factors or global change needs to be further studied.

关键词： Remote sensing Qinghai Lake desertification classification

Evolution of desertification Types on the North Shore of Qinghai Lake

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Computers, Materials & Continua 2022年第5期71卷 3635-3646页

作者： Wenzheng Yu Jintao Cui Yang Gao Mingxuan Zhu Li Shao Yanbo Shen Xiaozhao Zhang Chen Guo Hanxiaoya Zhang School of Geographical Sciences Nanjing University of Information Science&TechnologyNanjing210044China College of Hydrology and Water Resources Hohai UniversityNanjing210098China School of Environmental Science&Engineering Nanjing University of Information Science&TechnologyNanjing210044China Public Meteorological Service Center China Meteorological AdministrationBeijing100081China Center for Wind and Solar Energy Resources China Meteorological AdministrationBeijing100081China China Huaneng Group Co. Ltd.Beijing100036China China Huaneng Group Cleaning Energy Technology Academy Co. Ltd.100081China Faculty of Science The University of Auckland1010New Zealand

Land desertification is a widely concerned ecological environment *** the evolution trend of desertification types is of great significance to prevent and control land *** this study,we applied the decision tree classification method,to study the land area and temporal and spatial change law of different types of desertification in the North Bank of Qinghai Lake area from 1987 to 2014,based on the current land use situation and TM remote sensing image data of Haiyan County,Qinghai Province,The results show that the area of mild desertification land and moderate desertification land in the study area has decreased,while the area of severe desertification land and extreme desertification land has increased significantly in the past 30 *** area of desertification land decreased by 4.02 km2,of which the area of mild and moderate desertification land decreased by 39.73 km2 and 36.8 km2 respectively,and the area of severe and extreme desertification land increased by 32.78 km2 and 39.73 km2 *** for the mutual transformation relationship,the transformation from severe desertification land to extreme desertification land is the main,and the junction of severe desertification land and extreme desertification land is the sensitive area of *** the north shore of Qinghai Lake,the sandy land tends to expand *** research provides reference basis for local land desertification monitoring,and has a great guidance for local effective land desertification and soil and water conservation.

关键词： Qinghai Lake desertification evolution mechanism remote sensing

Assessing the relative role of climate change and human activities in desertification of North China from 1981 to 2010

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Frontiers of Earth Science 2019年第1期13卷 43-54页

作者： Duanyang XU Alin SONG Dajing LI Xue DING Ziyu WANG Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China Institute of Agricultural Resources and Regional Planning of Chinese Academy of Agricultural Sciences Beijing 100081China College of Resources and Environment Northeast Agricultural UniversityHarbin 150030China College of Forestry Beijing Forestry UniversityBeijing 100083China

desertification is a severe environmental problem induced by both climate change and human *** study assessed the relative contribution of climate change,human activities,and different climatic and anthropogenic factors in desertification reversion and expansion of North China from 1981 to *** results showed that the desertification of North China had changed significantly over the past 30 years;desertification reversion and expansion covered an area of 750,464 km^2, and the spatial distribution of these regions exhibited considerable *** desertification reversion, climate change and human activity accounted for 22.6% and 26%,respectively of total reverted *** speed reduction and the improvement ofhydrothermal conditions were the most important climatic factors for desertification reversion in the arid region of Northwest China (ARNC) and the Three-River Headwaters region (TRHR),and the reduction in grassland use intensity was the most important anthropogenic factor related to desertification reversion in Inner Mongolia and regions along the Great Wall (IMGW). For desertification expansion,the relative role of climate change was more obvious,which was mainly attributed to the continuous reduction in precipitation in eastern IMGW, and the increase in grassland use intensity was the main factor underlying regional human-induced desertification expansion.

关键词： desertification climate change human activity relative role North China

Assessment of desertification in Eritrea: land degradation based on Landsat images

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Journal of Arid Land 2019年第3期11卷 319-331页

作者： Mihretab G GHEBREZGABHER YANG Taibao YANG Xuemei WANG Congqiang Institute of Glaciology and Eco-Geography College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China College of Business and Social Sciences Adi Keihi 59Eritrea Gansu Desert Control Research Institute Lanzhou 730070China

Remote sensing is an effective way in monitoring desertification dynamics in arid and semi-arid *** this study,we used a decision tree method based on NDVI(normalized difference vegetation index),SAVI(soil adjusted vegetation index),and vegetation cover proportion to quantify and analyze the desertification in Eritrea using Landsat data of the 1970 s,1980 s and *** results demonstrate that the NDVI value and the annual mean precipitation declined while the temperature increased over the past 40 *** desertified land increased from 4.82×10^4 km^2(38.5%)in the 1970 s to 8.38×10^4 km^2(66.9%)in 2014:approximately 85%of the land of the country was under serious desertification,which significantly occurred in arid and semi-arid lowlands of the country(eastern,northern,and western lowlands)with relatively scarce precipitation and high *** non-desertified area,mostly located in the sub-humid eastern escarpment,also declined from approximately 2.1%to 0.5%.The study concludes that the desertification is a cause of serious land degradation in Eritrea and may link to climate changes,such as low and unpredictable precipitation,and prolonged drought.

关键词： desertification Landsat images NDVI index SPI analysis Eritrea

An over review of desertification in Xinjiang,Northwest China

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Journal of Arid Land 2022年第11期14卷 1181-1195页

作者： YU Xiang LEI Jiaqiang GAO Xin State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and GeographyChinese Academy of SciencesUrumqi 830011China University of Chinese Academy of Sciences Beijing 100049China

desertification research in arid and semi-arid regions has always been actively *** China,the problem of desertification in Xinjiang has also received extensive *** to its unique geography,many scholars have conducted corresponding research on the desertification status of *** this paper,we comprehensively reviewed desertification in Xinjiang,and compared the underlying mechanisms of desertification and the status of desertification conditions after the implementation of ecological control *** a larger scale,desertification in Xinjiang can be divided into soil salinization inside oases and sandy desertification on the edges of *** activities are considered the main cause of desertification,but natural factors also contribute to varying *** on the mechanisms of desertification has effectively curbed the development of desertification,but unreasonable use of land resources accelerates the risk of *** desertification control,there are several key ***,desertification monitoring and the early warning of desertification expansion should be ***,monitoring and reversing soil salinization also play an important role in the interruption of desertification *** is very effective to control soil salinization through biological and chemical ***,the management of water resources is also essential,because unreasonable utilization of water resources is one of the main reasons for the expansion of desertification in *** to the unreasonable utilization of water resources,the lower reaches of the Tarim River are cut off,which leads to a series of vicious cycles,such as the deterioration of ecological environment on both sides of the river and the worsening of ***,in recent years,various desertification control projects implemented in Xinjiang according to the conditions of different regions have achieved remarkable *** future studies,resea

关键词： desertification soil salinization sandy desertification desertification control soil wind erosion human activities Tarim Basin

A STUDY ON desertification OF WEST JILIN PROVINCE BASED ON REMOTE SENSING AND GIS TECHNIQUES

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Chinese Geographical Science 2002年第1期12卷 73-79页

作者： ZHU Jin hua, LI Jin song(Changchun Institute of Geography, the Chinese Academy of Sciences, Changchun 130021, P.R. China) Changchun Institute of Geography the Chinese Academy of Sciences Changchun P. R. China

'West Jilin Province' in this paper means Zhenlai, Baicheng, Taonan, Da'an,Tongyu, Fuyu, Songyuan, Qian'an, Changling, also includes Gongzhuling, Shuangliao, Lishu, Siping andNong' an which have been suffered from desertification. In west Jilin Province there are three sandzones passing through, they are Xiang (Xianghai) -Wu (Ulan Tug) sand zone, Hai-Feng sand zone, andTao'er River right bank sand zone. The desertification area of west Jilin Province is 819 100 ha,making up 12. 5% of the total land area. Among desertification types, in Jilin Province lightdesertification is the major, then is medium decertification, hevey desertification is the *** to the comparison of the interpretation results of the Landsat images of the 1980s and the1990s by remote sensing and GIS techniques, it can be seen that the desertification area in westJilin Province basically didn't change on the whole, only increased 6130 ha, making up 0. 8% of thedesertification area, change scale is less than 1%. Evidently, desertification is controlled mostly,but some areas are continuing deterioration. The desertification process of China can be dividedinto three types according to origin nature, they are sandy steppe desertification, fixed sandarea(sand land) activation and dunes transfer invasion. Reasons of desertification of West JilinProvince are analyzed, they include natural factors (such as material source factors, chimatefactors) and artificial factors (such as destroying grass to reclaim, steppe decreasing greatly,illegally feeling shelter forest stands, constructing reservoir to influence eco-environment etc. ).Some suggestions are put forward as follows: establishing the social project for ecologicalreconstruction of degenerated land; intensifying planning and management of land use, revertingfarmland into forestland or pasture in a planned way. The key desertification control is to dependmainly on policy and management, then control techniques.

关键词： remote sensing (RS) and GIS techniques desertification west jilin province

Factor influencing land degradation sensitivity and desertification in a drought prone watershed in Thailand

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International Soil and Water Conservation Research 2021年第2期9卷 217-228页

作者： Saowanee Wijitkosum Environmental Research Institute Chulalongkorn University Phayathai RoadPathumwanBangkok10330Thailand

This study aimed to assess land degradation sensitivity of an area contributing to desertification risk in Lam Ta Kong Watershed using Environmental Sensitivity Area Index(ESAI).Five risk factors comprised climatic,soil,geographical,land utilization and vegetation,and water resources factors together with fifteen sub-factors were used to analyze the sensitivity to land *** spatial analysis was calculated using Geographic Information System(GIS)and Remote Sensing(RS)*** key factors influencing land degradation risks in the watershed area were analyzed using the triangular fuzzy numbers(TFNs)*** results showed that approximately 33%of Lam Ta Kong watershed was affected by a high desertification risk excluded the water bodies and around 24.64%of the area suffered from a moderate *** research pointed out that key factors causing land degradation and desertification in the watershed area were related to the soil factors,followed by climatic,geographical factors,water resources,and land utilization and vegetation,*** results of this study can be used as a database for planning and implementing area-based mitigations and measures as well as for land use planning in the watershed area.

关键词： Land degradation desertification Critical factor Medalus Triangular fuzzy numbers