KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 中亚土地退化时空格局研究 | |
| Alternative Title | Study on the Spatiotemporal Pattern of Land Degradation in Central Asia |
| 姜亮亮 | |
| Subtype | 博士 |
| Thesis Advisor | 包安明 ; 古丽·加帕尔 ; Philippe De Maeyer |
| 2020-06-30 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 理学博士 |
| Keyword | 土地退化 驱动力 中亚 阿姆河三角洲 咸海流域 Land degradation Driving force Central Asia Amudarya River delta Aral Sea basin |
| Abstract | 土地退化已成为全球最重要的社会经济和环境问题之一。根据联合国环境规划署的估计，土地退化影响到全球陆地面积的 1/3和近 20%的世界人口，在干旱、半干旱及亚湿润干旱地区的影响尤为突出，如果不采取恢复措施，将进一步恶化。土地退化直接导致贫困人口增加，已经成为世界各国广泛关注的全球性问题。 2015 年在联合国可持续发展峰会上，联合国发布了 17 个可持续发展目标（Sustainable Development Goals， SDGs），拟从 2015 年到 2030 年间以综合方式彻底解决社会、经济和环境三个维度发展问题，转向可持续发展道路。联合国可持续发展目标 15.3（SDG 15.3）提出： 制止和扭转土地退化、 减少生物多样性的丧失， 并呼吁在 2030 年前实现土地退化零增长目标。中亚是世界上最大的干旱地区之一，水资源时空不匀，生态环境极为脆弱。近几十年来，在人类活动和气候变化双重作用下，土地退化问题越来越严重，其中最具典型性的咸海萎缩引起的一系列生态环境问题，已经给当地生产生活造成严重影响，被联合国称为“20世纪最严重的环境灾难”。长期以来，中亚土地退化监测和驱动机制研究很少得到关注，因此，有必要开展本研究，为中亚地区 2030 年实现土地退化零增长提供科学支撑。本文开展了不同尺度的土地退化时空变化特征及其驱动因素研究，在构建中亚干旱区土地退化监测与评价体系基础上，分析了中亚地区植被退化和土地退化的时空格局，评估了中亚土地退化敏感性，量化了阿姆河三角洲土地退化的主要驱动力，分析了水分压力对咸海流域农田的影响。主要结论总结如下：（1）中亚，灌木和稀疏植被退化面积要高于林地、草地和耕地。 卡拉库姆和克孜勒库姆沙漠、乌斯秋尔特高原和阿姆河三角洲的稀疏植被退化要比其他区域更为严重。 此外，中亚西部地区的土地退化显著， 其中乌斯秋尔特高原的土地退化较严重， 平均土地退化指数（LDI）高达 0.8，而东部则出现明显土地改善。根据土地退化变化年检测， 大多数植被类型的突变年主要集中在 1993-2002 年期间。（2） 卡拉库姆和克孜勒库姆沙漠的土地退化风险较大， 平均 ESAI 高达1.601。而哈萨克斯坦北部和山区的土地退化风险较低，平均 ESAI 低至 1.112。2008 年前土地退化风险逐渐增加（与 1992 年相比有所增加）， 而 2008 年后有所改善。 收敛性分析结果表明， 中亚大部分地区土地退化敏感性在 1992-2000年期间趋于发散，并在随后时间段内（2000-2008 年和 2008-2015 年）趋于收敛。（3） 不同地区不同植被类型的土地退化过程的主要驱动因素不同。 在1991年苏联解体后， 牧场遗弃是影响哈萨克斯坦东部、塔吉克斯坦和吉尔吉斯斯坦东部草地改善的主要驱动力。 乌斯秋尔特高原南部的稀疏植被和哈萨克斯坦北部耕地的土地退化过程易受到人为活动影响：稀疏植被土地的油气勘探和耕地撂荒。总体上，林地和稀疏植被的土地退化过程主要受气候变化影响，而耕地和草地的土地退化过程中到人类活动影响较大。（4） 阿姆河三角洲， 1990-2015 年期间卡拉卡尔帕克斯坦北部的土地退化较为严重， 变化幅度值（ΔM） 高达 0.38。 土地退化迫使三角洲的土地利用发生变化，有 920.75 km2 和 183.10 km2 的撂荒地分别转变为稀疏植被和草地。不同时间段内土地退化的主要驱动力不同。 1990-2000 年期间， 农业用水和降水减少是影响耕地和天然植被土地退化的主要驱动因素。 与其相反， 2000-2015 年期间，盐分排放到田间地块是不同植被土地退化的主要驱动力。（5） 咸海流域， 卡拉卡尔帕克斯坦、 达绍古兹和卡拉库姆地区水分压力较高，年均水分压力指数（WSI） 值为 0.99， 而阿姆河上游和卡拉达里亚地区的水分压力较低，年均 WSI 值为 0.65。 因此，下游地区的水分压力比上游地区更为严重。 下游地区水分压力呈增加趋势，导致该地区土地退化严重。 水分压力变化突变年份主要为 2005 年、 2008 年和 2010 年。下游平原区的农业用水、水分压力和土地退化之间的相关性均强于上游山区，且农业用水对下游地区的种植强度和棉花产量影响较大。 由于各国家的灌溉计划和耕作模式不同， 达绍古兹和卡拉卡尔帕克斯坦的水分压力和土地退化的空间差异性明显。 |
| Other Abstract | Globally, land degradation had become one of the most critical environmental andsocio-economic issues. According to estimates by the United Nations Convention toCombat Desertification (UNCCD), One-third of the global land area is threatened bythe effects of land degradation, which relates to 20% of the global population, especiallyin arid, semi-arid and sub-humid arid regions. Land degradation will worsen withoutrapid remedial actions. Land degradation directly results in an increase in the numberof poor people, and it has become a global problem that has attracted widespreadattention in the world. In the United Nations Sustainable Development Summit in 2015，the United Nations (UN) released 17 Sustainable Development Goals (SDGs). ThisSummit planned to comprehensively solve the three dimensions of social, economicand environmental development issues from 2015 to 2030, and turn to sustainabledevelopment. SDG 15.3 proposes: by 2030, restore degraded land and soil, reducebiodiversity loss, and strive to achieve a land degradation-neutral world. Central Asiahas one of the world’s largest arid regions, which contains uneven spatial and temporaldistribution of water resources. It is characterized by a fragile ecological environment.In recent decades, due to the dual effects of human activities and climate change, landdegradation has become more serious. The most typical series of ecological andenvironmental problems were caused by the shrinking of the Aral Sea, which haveseriously affected local production and life. The UN called it "the worst environmentaldisaster of the 20th century in the world". For a long time, monitoring land degradationand its driving mechanisms has received little attention. Therefore, it is important andnecessary to carry out this study to provide scientific support for achieving zero netland degradation in Central Asia by 2030.To meet these requirements, this dissertation explored spatiotemporalcharacteristics of land degradation and its driving factors on different scales. Theobjectives of this dissertation are to (1) analyze the spatiotemporal patterns of vegetationdegradation in Central Asia; (2) monitor the spatiotemporal characteristics of landdegradation process in Central Asia; (3) assess sensitivity to land degradation in CentralAsia; (4) quantify the main drivers of land degradation in the Amudarya River delta (AD) and (5) detect effects of water stress on croplands in the Aral Sea basin (ASB).Regarding these objectives, the main findings are summarized as follows:(1) In Central Asia, more areas with vegetation degradation were located in areasof shrubs and sparse vegetation than in those corresponding to forests, grasslands andcrops. The degradation of sparse vegetation was more serious in the Karakum andKyzylkum Deserts, the Ustyurt Plateau and the AD than in other regions. Furthermore,significant land degradation in the western part of Central Asia, with the most severedesertification occurring in the Ustyurt Plateau, with mean land degradation indexes(LDIs) as high as 0.8, whereas a significant land improvement was identified in theeastern part of Central Asia. According to a change-year analysis, mutation years ofland degradation were observed from 1993 to 2002 for most vegetation types.(2) In Central Asia, high values were concentrated in the Kyzylkum and KarakumDeserts, with mean environmentally sensitive area indexs (ESAIs) of 1.601, whereaslow average ESAI values were observed in northern Kazakhstan and mountainousregions, with mean ESAI values as low as 1.112. Land degradation risk (LDR)gradually increased in 2008 (more than in 1992) and improved after 2008. Theconvergence analysis revealed that the land degradation sensitivity trend divergedbetween 1992 and 2000 and converged over the subsequent time periods (2000-2008and 2008-2015) in most regions of Central Asia.(3) In Central Asia, the land degradation process of different vegetation types anddifferent regions resulted from different major driving factors. For grasslands in easternKazakhstan, Tajikistan and Kyrgyzstan, pasture abandonment was a major drivingfactor affecting land improvement after the disintegration of the Soviet Union in 1991.The land degradation process of sparse vegetation and croplands was expanded andtriggered by human activities: oil and gas exploration in the southern Ustyurt Plateauand agricultural abandonment in northern Kazakhstan. The land degradation process inforests and areas of sparse vegetation was mainly caused by climatic variations, whilethat in croplands and grasslands was greatly affected by human activities.(4) In the Amudarya River delta (AD), land degradation was especiallyconcentrated in the downstream areas of northern Karakalpakistan throughout the studyperiod (1990-2015), with magnitude values amounting to 0.38. Land degradation couldforce land use changes in the AD. 920.75 km2 and 183.10 km2 of abandoned croplandswere converted to sparse vegetation and grasslands, respectively. Land degradation over different time intervals was caused by several major driving factors. From 1990-2000, water withdrawal availability and decreased precipitation were the mostinfluential factors explaining the land degradation of croplands and natural vegetation,respectively. In contrast, the salt discharge to the field plot was a major force causingland degradation of different vegetation types in the subsequent time interval (2000-2015).(5) In the Aral Sea basin (ASB), higher water stress index (WSI) values were foundin Karakalpakstan, Tashauz and Karakum, with a mean of 0.9, while low average WSIswere identified in the Karadarya and Amu upstream areas, with a mean of 0.65. Thus,water stress in the downstream areas was more serious than that in the upstream areas.The downstream regions experienced an increasing tendency of water stress, resultingin severe land degradation. 2005, 2008 and 2010 were the main years with abruptchanges in the water stress index (WSI). The correlations between agricultural waterconsumption, water stress and land degradation in the downstream plain zone werestronger than those in the upstream mountainous zone. Subsequently, the agriculturalwater consumption had a great influence on the cropping intensity and cotton yield inthe downstream regions. Because each country has its own irrigation schemes andcropping patterns, the results of water stress and land degradation revealed an obviousspatial defference between Tashauz and Karakalpakstan. |
| Subject Area | 地图学与地理信息系统 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/15426 |
| Collection | 中国科学院新疆生态与地理研究所 研究系统 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 姜亮亮. 中亚土地退化时空格局研究[D]. 北京. 中国科学院大学,2020. |
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