Li Rui 李 睿 the United Graduate School of Agricultural Sciences

Total Page:16

File Type:pdf, Size:1020Kb

Li Rui 李 睿 the United Graduate School of Agricultural Sciences Agricultural drought management in Northeast China and Inner Mongolia 中国東北部と内モンゴルにおける農業干ばつの管理 Li Rui 李 睿 The United Graduate School of Agricultural Sciences Tottori University, Japan 2015 Agricultural drought management in Northeast China and Inner Mongolia 中国東北部と内モンゴルにおける農業干ばつの管理 A thesis presented to The United Graduate School of Agricultural Sciences In partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Li Rui 李 睿 The United Graduate School of Agricultural Sciences Tottori University, Japan 2015 TABLE OF CONTENTS TABLE OF CONTENTS ........................................................................................................ I LIST OF FIGURES ............................................................................................................ IV LIST OF TABLES ............................................................................................................... VI SUMMARY ........................................................................................................................ VII 摘 要 ................................................................................................................................. XII ACKNOWLEGEMENTS ................................................................................................... XV ABBREVIATIONS ........................................................................................................... XVII Chapter 1 ............................................................................................................................. 1 General introduction ............................................................................................................ 1 1.1 The terminology related with agricultural drought .................................................. 1 1.1.1 Drought concepts ......................................................................................... 1 1.1.2 Drought types ............................................................................................... 1 1.1.3 Aridity, water shortage and drought ............................................................. 2 1.2 Drought in the world ............................................................................................... 3 1.3 Reviews of drought researches .............................................................................. 3 1.3.1 Climate background and drought ................................................................. 3 1.3.2 Basic characteristics of drought and drought indices .................................. 5 1.3.3 The prediction of drought impact on vegetation......................................... 10 1.3.4 Drought monitoring framework................................................................... 11 1.3.5 Modeling of water stress ............................................................................ 11 1.3.6 The impact of agricultural drought and drought mitigation assessment .... 18 1.4 The impact of drought on crop physiology ........................................................... 19 1.5 The objectives of the thesis .................................................................................. 20 1.6 The structure of the thesis .................................................................................... 22 Chapter 2 ........................................................................................................................... 23 Temporal-spatial precipitation variation in Northeast China and Inner Mongolia .............. 23 2.1 Background .......................................................................................................... 23 2.2 Study area ............................................................................................................ 23 2.3 Data and Method .................................................................................................. 24 2.3.1 Data ............................................................................................................ 24 2.3.2 Method ....................................................................................................... 26 2.4 Results .................................................................................................................. 26 2.4.1 Temporal pattern of precipitation from 1961-2010 ..................................... 27 2.4.2 Spatial pattern of seasonal precipitation variation ..................................... 29 2.4.3 Spatial pattern of annual precipitation trend .............................................. 29 2.5 Discussion ............................................................................................................ 30 2.6 Conclusion ............................................................................................................ 30 Chapter 3 ........................................................................................................................... 32 Index-based agricultural drought monitoring in Hailar County, Inner Mongolia ................ 32 3.1 Background .......................................................................................................... 32 3.2 Study area ............................................................................................................ 34 3.3 Conceptual model of the agricultural drought process ........................................ 36 I 3.4 Data and Method .................................................................................................. 36 3.4.1 Data ............................................................................................................ 36 3.4.2 Method ....................................................................................................... 38 3.5 Results .................................................................................................................. 39 3.5.1 Seasonal trends of drought indices ........................................................... 39 3.5.2 Relationships of drought indices with crop yield ........................................ 40 3.5.3 Temporal relationships between drought indices ....................................... 41 3.5.4 Drought assessment .................................................................................. 42 3.6 Discussion ............................................................................................................ 45 3.6.1 Recent trends of climate and agricultural drought in Hailar County .......... 45 3.6.2 Critical growth stages related with yield reduction ..................................... 46 3.6.3 Time lags between water deficit and NDVI ................................................ 47 3.6.4 Feasibility of SPI, CMI, and NDVI for monitoring agricultural drought ...... 48 3.7 Conclusion ............................................................................................................ 48 Chapter 4 ........................................................................................................................... 50 Agricultural drought severity assessment based on a crop model ................................... 50 4.1 Introduction ........................................................................................................... 50 4.2 Materials and methods ......................................................................................... 52 4.2.1 Description of study area ........................................................................... 52 4.2.2 Agricultural drought assessment framework .............................................. 54 4.2.3 Model calibration and validation ................................................................ 55 4.2.4 Drought index assessment and framework validation ............................... 56 4.2.5 Soil moisture simulation ............................................................................. 58 4.2.6 Data sources and collection ....................................................................... 58 4.3 Results and Discussion ........................................................................................ 60 4.3.1 Crop model performance ........................................................................... 60 4.3.2 Agricultural drought indices assessment ................................................... 62 4.3.3 Validation of assessment framework ......................................................... 67 4.3.4 The relationship between soil moisture simulation and CMI ..................... 69 4.4 Conclusions .......................................................................................................... 70 Chapter 5 ........................................................................................................................... 71 The comparison of agricultural practices to mitigate drought by the crop model ............. 71 5.1 Introduction ........................................................................................................... 71 5.2 Date and Methods ................................................................................................ 73 5.2.1 Study area .................................................................................................. 73 5.2.2 Materials ..................................................................................................... 74 5.2.3 Agricultural practices .................................................................................. 76 5.3 Results
Recommended publications
  • Table of Codes for Each Court of Each Level
    Table of Codes for Each Court of Each Level Corresponding Type Chinese Court Region Court Name Administrative Name Code Code Area Supreme People’s Court 最高人民法院 最高法 Higher People's Court of 北京市高级人民 Beijing 京 110000 1 Beijing Municipality 法院 Municipality No. 1 Intermediate People's 北京市第一中级 京 01 2 Court of Beijing Municipality 人民法院 Shijingshan Shijingshan District People’s 北京市石景山区 京 0107 110107 District of Beijing 1 Court of Beijing Municipality 人民法院 Municipality Haidian District of Haidian District People’s 北京市海淀区人 京 0108 110108 Beijing 1 Court of Beijing Municipality 民法院 Municipality Mentougou Mentougou District People’s 北京市门头沟区 京 0109 110109 District of Beijing 1 Court of Beijing Municipality 人民法院 Municipality Changping Changping District People’s 北京市昌平区人 京 0114 110114 District of Beijing 1 Court of Beijing Municipality 民法院 Municipality Yanqing County People’s 延庆县人民法院 京 0229 110229 Yanqing County 1 Court No. 2 Intermediate People's 北京市第二中级 京 02 2 Court of Beijing Municipality 人民法院 Dongcheng Dongcheng District People’s 北京市东城区人 京 0101 110101 District of Beijing 1 Court of Beijing Municipality 民法院 Municipality Xicheng District Xicheng District People’s 北京市西城区人 京 0102 110102 of Beijing 1 Court of Beijing Municipality 民法院 Municipality Fengtai District of Fengtai District People’s 北京市丰台区人 京 0106 110106 Beijing 1 Court of Beijing Municipality 民法院 Municipality 1 Fangshan District Fangshan District People’s 北京市房山区人 京 0111 110111 of Beijing 1 Court of Beijing Municipality 民法院 Municipality Daxing District of Daxing District People’s 北京市大兴区人 京 0115
    [Show full text]
  • Seroprevalence of Toxoplasma Gondii Infection in Sheep in Inner Mongolia Province, China
    Parasite 27, 11 (2020) Ó X. Yan et al., published by EDP Sciences, 2020 https://doi.org/10.1051/parasite/2020008 Available online at: www.parasite-journal.org RESEARCH ARTICLE OPEN ACCESS Seroprevalence of Toxoplasma gondii infection in sheep in Inner Mongolia Province, China Xinlei Yan1,a,*, Wenying Han1,a, Yang Wang1, Hongbo Zhang2, and Zhihui Gao3 1 Food Science and Engineering College of Inner Mongolia Agricultural University, Hohhot 010018, PR China 2 Inner Mongolia Food Safety and Inspection Testing Center, Hohhot 010090, PR China 3 Inner Mongolia KingGoal Technology Service Co., Ltd., Hohhot 010010, PR China Received 6 January 2020, Accepted 8 February 2020, Published online 19 February 2020 Abstract – Toxoplasma gondii is an important zoonotic parasite that can infect almost all warm-blooded animals, including humans, and infection may result in many adverse effects on animal husbandry production. Animal husbandry in Inner Mongolia is well developed, but data on T. gondii infection in sheep are lacking. In this study, we determined the seroprevalence and risk factors associated with the seroprevalence of T. gondii using an indirect enzyme-linked immunosorbent assay (ELISA) test. A total of 1853 serum samples were collected from 29 counties of Xilin Gol League (n = 624), Hohhot City (n = 225), Ordos City (n = 158), Wulanchabu City (n = 144), Bayan Nur City (n = 114) and Hulunbeir City (n = 588). The overall seroprevalence of T. gondii was 15.43%. Risk factor analysis showed that seroprevalence was higher in sheep 12 months of age (21.85%) than that in sheep <12 months of age (10.20%) (p < 0.01).
    [Show full text]
  • Human Brucellosis Occurrences in Inner Mongolia, China: a Spatio-Temporal Distribution and Ecological Niche Modeling Approach Peng Jia1* and Andrew Joyner2
    Jia and Joyner BMC Infectious Diseases (2015) 15:36 DOI 10.1186/s12879-015-0763-9 RESEARCH ARTICLE Open Access Human brucellosis occurrences in inner mongolia, China: a spatio-temporal distribution and ecological niche modeling approach Peng Jia1* and Andrew Joyner2 Abstract Background: Brucellosis is a common zoonotic disease and remains a major burden in both human and domesticated animal populations worldwide. Few geographic studies of human Brucellosis have been conducted, especially in China. Inner Mongolia of China is considered an appropriate area for the study of human Brucellosis due to its provision of a suitable environment for animals most responsible for human Brucellosis outbreaks. Methods: The aggregated numbers of human Brucellosis cases from 1951 to 2005 at the municipality level, and the yearly numbers and incidence rates of human Brucellosis cases from 2006 to 2010 at the county level were collected. Geographic Information Systems (GIS), remote sensing (RS) and ecological niche modeling (ENM) were integrated to study the distribution of human Brucellosis cases over 1951–2010. Results: Results indicate that areas of central and eastern Inner Mongolia provide a long-term suitable environment where human Brucellosis outbreaks have occurred and can be expected to persist. Other areas of northeast China and central Mongolia also contain similar environments. Conclusions: This study is the first to combine advanced spatial statistical analysis with environmental modeling techniques when examining human Brucellosis outbreaks and will help to inform decision-making in the field of public health. Keywords: Brucellosis, Geographic information systems, Remote sensing technology, Ecological niche modeling, Spatial analysis, Inner Mongolia, China, Mongolia Background through the consumption of unpasteurized dairy products Brucellosis, a common zoonotic disease also referred to [4].
    [Show full text]
  • Minimum Wage Standards in China August 11, 2020
    Minimum Wage Standards in China August 11, 2020 Contents Heilongjiang ................................................................................................................................................. 3 Jilin ............................................................................................................................................................... 3 Liaoning ........................................................................................................................................................ 4 Inner Mongolia Autonomous Region ........................................................................................................... 7 Beijing......................................................................................................................................................... 10 Hebei ........................................................................................................................................................... 11 Henan .......................................................................................................................................................... 13 Shandong .................................................................................................................................................... 14 Shanxi ......................................................................................................................................................... 16 Shaanxi ......................................................................................................................................................
    [Show full text]
  • Understanding Land Use and Land Cover Change in Inner Mongolia Using Remote Sensing Time Series
    Humboldt-Universität zu Berlin – Geographisches Institut Understanding land use and land cover change in Inner Mongolia using remote sensing time series DISSERTATION Zur Erlangung des akademischen Grades doctor rerum naturalium (Dr. rer. nat.) Im Fach Geographie eingereicht an der Mathematisch-Naturwissenschaftlichen Fakultät II der Humboldt-Universität zu Berlin von M.Sc. He Yin Präsident der Humboldt-Universität zu Berlin Prof. Dr. Jan-Hendrik Olbertz Dekan der Mathematisch-Naturwissenschaftlichen Fakultät II Prof. Dr. Elmar Kulke Gutachter: Prof. Dr. Patrick Hostert Prof. Dr. Thomas Udelhoven Prof. Dr. Tobias Kümmerle Eingereicht: 06. Juni 2014 Tag der Verteidigung: 05. September 2014 ii iv Abstract Monitoring land use and land cover change (LULCC) support better interpretation about how land surfaces are impacted by human decisions. The overall aim of this thesis is to gain a better understanding about LULCC in Inner Mongolia using remote sensing under consideration of China’s land use policies. With the largest scale land restoration programs in the world, China aims to reduce human pressure on lands and promote sustainable land use. As a hot-spot of environmental change, Inner Mongolia received the heaviest investment from the central government for land restoration. Yet the effectiveness and consequences of China’s land use policies in Inner Mongolia remain unclear. Remote sensing is an effective tool for monitoring land use and land cover change across broad scales, yet data limitations and a lack of available change detection methods hampers the capacity of researchers to apply remote sensing techniques for LULCC monitoring. To reliably map LULCC in Inner Mongolia, the opportunities and limitations of using coarse resolution imagery time series for monitoring long-term land changes was first examined.
    [Show full text]
  • A Case Study in the Xilin Gol League, Inner Mongolia
    International Journal of Environmental Research and Public Health Article Quantifying the Impact of the Grain-for-Green Program on Ecosystem Health in the Typical Agro-Pastoral Ecotone: A Case Study in the Xilin Gol League, Inner Mongolia Zhaoyi Wang 1,2, Qianru Yu 1 and Luo Guo 1,* 1 College of the Life and Environmental Science, Minzu University of China, Beijing 100081, China; [email protected] (Z.W.); [email protected] (Q.Y.) 2 Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117570, Singapore * Correspondence: [email protected] Received: 23 May 2020; Accepted: 30 July 2020; Published: 5 August 2020 Abstract: The Green-for-Grain program (GGP) is the largest environmental restoration program in China. It is effective in controlling land desertification but at the same time is highly affected by regional differences. Ecosystem health, as an important indicator of ecosystem sustainability, can effectively assess the ecological impact of the GGP and provide a basis for follow-up actions. As a typical agro-pastoral ecotone along the Great Wall, the Xilin Gol League has seen increasing land-use intensity, thus, it is crucial to understand the ecological conditions of the region in order to deploy a policy of the GGP in accordance with local conditions. In this study, using remote sensing images and social statistics data from 1990–2015, land-use transformation and the turning point of vegetation coverage was determined. Based on the pressure-state-response (PSR) model, an ecological health evaluation system was constructed to quantify the temporal and spatial variation of ecosystem health.
    [Show full text]
  • Pipe Dreams: Datang’S Failed Coal Chemical Initiative, and the Story of China’S Coal Chemical Sector
    大唐煤化工的折戟沉沙 大唐煤化工的折戟沉沙 Copyright and Disclaimer This report is written by Greenpeace East Asia Regional Office (hereafter referred to as “Greenpeace”). READING THIS REPORT IS CONSIDERED AS YOU HAVE CAREFULLY READ AND FULLY UNDERSTAND THIS COPYRIGHT STATEMENT AND DISCLAIMER, AND AGREE TO BE BOUND BY THE FOLLOWING TERMS. 1. Copyright Statement This report is published by Greenpeace East Asia (herein referred as “Greenpeace”). Greenpeace holds the exclusive ownership of the copyright of this report. 2. Disclaimer a) This report is originally written in English and translated into Chinese subsequently. In case of a discrepancy, the English version prevails. b) This report is ONLY for the public interests purposes of information sharing for environmental protection. Therefore, the report should not be used as the reference of any investment activities or other decision-making process. If so used, Greenpeace is exempt from any liabilities arising from such use. c) The content of this report is based on officially published information Greenpeace independently obtained during the time of research. Greenpeace does not guarantee the promptness, accuracy and thoroughness of the information contained in this report. 大唐煤化工的折戟沉沙 Table of Contents 1. Introduction 1 2. China’s coal chemical sector 3 3. Datang Makes a Move 7 4. Funding Datang’s Move into Coal Chemical: The Initial Impetus 11 5. The Policy Environment: Consistently Inconsistent 13 6. A Long and Winding Road: The Short Version 17 7. A Long and Winding Road: The Long Version 19 8. After the Fire: Why did Datang Give Up 39 1) Change of Leadership at Datang 2) Financial Difficulties 41 3) Continued operational difficulties 44 47 9.
    [Show full text]
  • Impact of Climate Change on the Water Requirements of Oat in Northeast and North China
    water Article Impact of Climate Change on the Water Requirements of Oat in Northeast and North China Hao Jia 1,2 , Ting Zhang 1,2, Xiaogang Yin 1,2, Mengfei Shang 1,2, Fu Chen 1,2, Yongdeng Lei 1,2,* and Qingquan Chu 1,2,* 1 College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China; [email protected] (H.J.); [email protected] (T.Z.); [email protected] (X.Y.); [email protected] (M.S.); [email protected] (F.C.) 2 Key Laboratory of Farming System, Ministry of Agriculture and Rural Affairs, Beijing 100193, China * Correspondence: [email protected] (Q.C.); [email protected] (Y.L.); Tel.: +86-10-62731207 Received: 22 October 2018; Accepted: 30 December 2018; Published: 8 January 2019 Abstract: Crop water requirements are directly affected by climatic variability, especially for crops grown in the areas which are sensitive to climatic change. Based on the SIMETAW model and a long-term meteorological dataset, we evaluated the spatiotemporal variations of climatic change impacts on water requirement of oat in North and Northeast China. The results indicated that effective rainfall showed an increasing trend, while the crop water requirement and irrigation demand presented decreasing trends over the past decades. The water requirement of oat showed significant longitudinal and latitudinal spatial variations, with a downtrend from north to south and uptrend from east to west. Climatic factors have obviously changed in the growth season of oat, with upward trends in the average temperature and precipitation, and downward trends in the average wind speed, sunshine hours, relative humidity, and solar radiation.
    [Show full text]
  • CWSI) for Monitoring Drought from 2001 to 2017 Over Inner Mongolia
    sustainability Article Characterization and Evaluation of MODIS-Derived Crop Water Stress Index (CWSI) for Monitoring Drought from 2001 to 2017 over Inner Mongolia Zi-Ce Ma 1, Peng Sun 1,2,3,* , Qiang Zhang 2,3,*, Yu-Qian Hu 1 and Wei Jiang 1 1 School of Geography and Tourism, Anhui Normal University, Wuhu 241002, China; [email protected] (Z.-C.M.); [email protected] (Y.-Q.H.); [email protected] (W.J.) 2 State Key Laboratory of Surface Process and Resource Ecology, Beijing Normal University, Beijing 100875, China 3 Academy of Disaster Reduction and Emergency Management, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China * Correspondence: [email protected] (P.S.); [email protected] (Q.Z.) Abstract: Inner Mongolia is one of the main green production bases of agricultural and animal husbandry products. Due to factors such as natural geographical location, drought occurs frequently in Inner Mongolia. Based on the MOD16 product and the method of crop water stress index (CWSI) combined with multi-year precipitation and temperature data, the spatial and temporal distribution characteristics and major influencing factors of drought in Inner Mongolia from 2001 to 2017 were analyzed. In order to provide effective scientific basis for drought control and drought resistance in Inner Mongolia for decision. The results showed that: (1) during 2001–2017, the average annual CWSI in Inner Mongolia had a strong spatial heterogeneity, which showed a trend of gradual increase from northeast to southwest. The annual average CWSI was 0.7787 and showed a fluctuating downward trend for Inner Mongolia. (2) The CWSI of every 8d during one year in Inner Mongolia showed the Citation: Ma, Z.-C.; Sun, P.; Zhang, double-peak trend, reaching its maximum of 0.9043 in the 121st day.
    [Show full text]
  • Xilingol League of Inner Mongolia Taked As an Example
    2019 2nd International Workshop on Advances in Social Sciences (IWASS 2019) Developing Characteristics and Optimal Strategic Decision of Traditional Horse Industry--Xilingol League of Inner Mongolia Taked as an Example Ai Yunhui, Wang Huaidong, Wang Ruixing, Xue Chen Vocational Technical College, Inner Mongolia Agricultural University, Baotou, Inner Mongolia, China Keywords: National Horse Industry, Development Evaluation, Strategy Analysis, Western Region Abstract: the Index System of Development Evaluation of National Horse Industry of Xilingol League Was Constructed in the Article to Reveal the Intensive Development and Characteristics of Various Regions of Xilingol League, and the Topsis Model Was Used in the Paper. on This Basis, the Structure Model of Strategic Decision-Making Analysis Was Constructed to Carry out Specific Strategic Measures. the Study Showed That There Were Significant Differences in the Development of the National Industry in Xilingol League, and Cities of Xilinhaote, Xiwuzhumuqin and Abaga Were At the First Development Level. Cities of Dongwuzhumuqin, Taipusi and Sunitezuo Wre in the Second Level, and Other Areas in the Third Level. the Development of Horse Industry Should Be Considered from Following Areas: to Protect the Horses in the Region, to Speed Up the Demonstration of Key Projects, to Optimize the Allocation of Resources and Play the Traditional Characteristics of the Region, to Develop National Horse Culture Development Model, to Establish National Horse Racing Mechanism, to Innovate Horse Product Development,
    [Show full text]
  • Spatial Analysis on Human Brucellosis Incidence in Mainland China: 2004–2010
    Open Access Research BMJ Open: first published as 10.1136/bmjopen-2013-004470 on 8 April 2014. Downloaded from Spatial analysis on human brucellosis incidence in mainland China: 2004–2010 Junhui Zhang,1,2 Fei Yin,1 Tao Zhang,1 Chao Yang,2 Xingyu Zhang,1 Zijian Feng,3 Xiaosong Li1 To cite: Zhang J, Yin F, ABSTRACT et al Strengths and limitations of this study Zhang T, . Spatial Objectives: China has experienced a sharply analysis on human increasing rate of human brucellosis in recent years. ▪ brucellosis incidence in Exploratory spatial data analysis methods and Effective spatial monitoring of human brucellosis mainland China: 2004–2010. the empirical Bayes smoothing technique were BMJ Open 2014;4:e004470. incidence is very important for successful used to analyse spatial patterns of incidence doi:10.1136/bmjopen-2013- implementation of control and prevention programmes. rates for human brucellosis at the county level in 004470 The purpose of this paper is to apply exploratory mainland China. Therefore, random variability spatial data analysis (ESDA) methods and the empirical was reduced, and greater stability of incidence Bayes (EB) smoothing technique to monitor county- ▸ Prepublication history for rates was provided mainly in small counties and this paper is available online. level incidence rates for human brucellosis in mainland true cluster areas with low false-positive rates To view these files please China from 2004 to 2010 by examining spatial performing especially well on outlier detection visit the journal online patterns. had a better chance of being detected. (http://dx.doi.org/10.1136/ Methods: ESDA methods were used to characterise ▪ The number of reported cases of human brucel- bmjopen-2013-004470).
    [Show full text]
  • Spatiotemporal Variation of Vegetation Coverage and Its
    sustainability Article Spatiotemporal Variation of Vegetation Coverage and Its Response to Climate Factors and Human Activities in Arid and Semi-Arid Areas: Case Study of the Otindag Sandy Land in China Hao Wang 1,2, Fei Yao 1,2, Huasheng Zhu 1,2,* and Yuanyuan Zhao 3 1 State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China; [email protected] (H.W.); [email protected] (F.Y.) 2 School of Geography, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China 3 Key Laboratory of State Forestry Administration on Soil and Water Conservation, Beijing Forestry University, Beijing 100083, China; [email protected] * Correspondence: [email protected]; Tel.: +86-10-5880-0193 Received: 4 June 2020; Accepted: 24 June 2020; Published: 26 June 2020 Abstract: Vegetation coverage is a key variable in terrestrial ecosystem monitoring and climate change research and is closely related to soil erosion and land desertification. In this article, we aimed to resolve two key scientific issues: (1) quantifying the spatial-temporal vegetation dynamics in the Otindag Sandy Land (OSL); and (2) identifying the relative importance of climate factors and human activities in impacting vegetation dynamics. Based on correlation analysis, simple regression analysis, and the partial derivative formula method, we examined the spatiotemporal variation of vegetation coverage in the OSL, belonging to the arid and semiarid region of northern China, and their interaction with climate-human factors. The results showed that the vegetation coverage of the area showed a downward trend with a rate of 0.0006/a during 2001–2017, and gradually decreased − from east to west.
    [Show full text]