Since the implementation of the government initiative-the Development of Western Regions for 2000-2019, a series of major ecological construction projects have been launched, leading to great changes in the ecological conditions and ecological services of western China. This study calculated the amount of total ecosystem services in the western region from 2000 to 2019, and analyzed ecological changes and the characteristics of spatio-temporal variations in ecological services. And a relevant analysis method was applied to explore the trade-offs and synergy of service. It was found that the area of settlements and wetland ecosystems in the study area increased significantly from 2000 to 2015, whereas grassland showed a downward trend year by year. The vegetation fraction showed a decreasing zonal distribution from south to north. A fluctuating increase was observed during 2000-2019, with inter-annual and large spatial differences. The water conservation service had a slight downward trend from 2000 to 2019, and the main decreasing areas were distributed in southeastern Tibet, the western part of the Three Rivers Source Region, and the karst rocky desertification area. The soil conservation service showed an increasing but fluctuating trend, with the greatest increases observed in the Loess Plateau, western Sichuan and Yunnan provinces, northwest Tibet, and southeast Tibet. The windbreak and sand fixation showed a downward trend, and the sharp decline was mainly found in the central and western parts of Inner Mongolia, Tibet and parts of northern Xinjiang. Ecosystem supply, water conservation, and soil conservation were synergistically connected, they were observed north of the Huaihe River-Qinling Mountains, especially in Ningxia and Inner Mongolia. Ecosystem supply was mainly trade-offs with windbreak and sand fixation, and it was observed in the farming-pastoral transitional zone. The synergistic degree of ecosystem services in areas subjected to ecological engineering policy was greater than that in non-engineering areas. Quantitative assessment of ecosystem service changes and their trade-offs is helpful for scientific ecological management and maximizing ecological benefits.

西部大开发战略实施20年以来,一系列重大生态建设工程使得西部地区的生态状况和生态服务发生了重要变化,本文分析西部地区生态状况变化及其生态服务时空变化特征,并运用相关分析法研究其服务功能权衡协同关系。研究发现西部地区2000—2019年间：① 聚落和湿地生态系统面积显著增加,草地有逐年下降趋势。② 植被覆盖度呈波动上升趋势,存在年际差异且空间差异较大。③ 水源涵养服务有轻微下降趋势,下降区域主要分布在藏东南地区、三江源西部地区、喀斯特石漠化地区等;土壤保持服务波动中呈上升趋势,上升区域主要黄土高原地区、川滇西部地区、藏西北地区、藏东南地区等;防风固沙服务呈下降趋势,大幅下降区域主要位于内蒙古中西部地区、西藏和北疆部分地区。④ 生态系统供给与水源涵养、土壤保持主要为协同关系,与防风固沙主要为权衡关系且分布在农牧交错带地区。⑤ 生态工程区内生态系统服务协同程度大于非工程区。定量评估生态系统服务变化及其权衡协同关系有助于进行科学化生态管理,最大化生态效益。

By making a evaluation index system and using AHP to determine the evaluation factor's weights, this paper builds the valuation model of eco-environmental stability of Tibet and uses the overlay function of raster-GIS to make a result map, and finds the distribution characteristics of eco-environmental stability of Tibet based on the analysis of result map. The study shows that the eco-environmental stability of Tibet is almost good and the unstable area that is only 9.78% of the total area of Tibet is distributed in the middle and low reaches of the Yarlung Zangbo river. To protect the eco-environmental of the unstable area from farther degenerating, the government should pay more attention on the eco-environmental construction work on this area.

The shelter function of Tibetan Plateau has an important effect on the ecological security in China, even in Asia. Under the joint influence of global change and human activities, ecosystem destabilizing and resources and environment pressure increasing emerge on the Tibetan Plateau, which have caused some problems, including significant glacier retreat, serious land degradation, aggravated soil erosion and water loss, increased threats to biodiversity along with decreased rare and specious biological resources, and natural disasters increasing. These problems have a great influence on regional ecological security shelter function on the plateau. Based on the relevant research and practical experience in ecological construction, some suggestions are proposed to strengthen ecological protection and construction of the national ecological security shelter zone on the Tibetan Plateau at present, namely, strengthening basic research on the Tibetan Plateau ecological shelter impacts and regional ecological security enhancement and climate change mitigation; developing the key technology of protection and construction of the national ecological security shelter zone on the plateau and demonstration; striving to set up a monitoring system of ecological shelter function, intensifying evaluation of protection and construction efficiency of ecological security shelter zone, perfecting evaluation systems and standards, and summarizing experience, so as to enhance the overall function of national ecological security shelter and to further take the initiative in dealing with global change.

青藏高原对我国乃至亚洲生态安全具有重要的屏障作用。在全球变化和人类活动的综合影响下,青藏高原呈现出生态系统稳定性降低、资源环境压力增大等问题,突出表现为:冰川退缩显著、土地退化形势严峻、水土流失加剧、生物多样性威胁加大与珍稀生物资源减少、自然灾害增多等。这些问题严重影响了青藏高原区域生态安全屏障功能的发挥。针对当前高原生态安全状况,在总结相关研究成果和生态建设实践经验的基础上,提出了加强青藏高原国家生态安全屏障保护与建设的对策建议：加强气候变化对青藏高原生态屏障作用影响及区域生态安全调控作用的基础研究;系统开展高原生态安全屏障保护和建设关键技术研究与示范推广;部署建设生态屏障功能动态监测体系,加强生态安全屏障保护与建设成效评估,构建评估体系和标准,并凝练经验,以系统提升国家生态安全屏障的总体功能,在应对全球变化中占据主动地位。

In this paper, we developed a series of assessment indexes based on the evaluation of ecological effects, which consists of the ecosystem structure, qualities, services, and main impacting factors for these changes. Comprehensive monitoring and assessment methods that focused on the planning objectives of ecological conservation and restoration project were developed based on field observation, remote sensing monitoring and quantitative simulation of ecological processes. Then we assessed the ecological effects of the first-stage of ecological conservation and restoration project in Sanjiangyuan region by adopting the trend analysis of dynamics in ecosystem structure and services. The results showed that since the beginning of the project eight years ago, the macro-situation of ecosystem in this region has been getting better but not reached the best situation in the 1970s. The continued degradation trends of grassland have been initially contained, but it is difficult to achieve the expected objective of "the vegetation coverage of grassland increasing by an average of 20%-40%". The wetland and water-body ecosystems have been restored. The water conservation service of ecosystem and water supply capacity of watershed were increased, and the volume of?ecosystem water conservation reached the objective of increasing by 1.32 billion m3. The ecological restoration in the project regions tended to be better than that outside the project regions. In addition to climate change, implementation of the ecological conservation and restoration project had obvious and positive effects on vegetation restoration. However, the degradation situations of grassland were not fundamentally reversed, and the implementation of the project has not been curbing the increasing trend of soil erosion. Therefore, the local and preliminary characteristics of the first-stage of the project highlighted the long-term and arduous ecosystem conservation and protection in the Sanjiangyuan region.

基于生态系统结构--服务动态过程趋势分析,针对生态保护与建设工程预期目标,构建了由生态系统结构,质量,服务及其变化因素构成的生态成效评估指标体系,研究发展野外观测,遥感监测和生态过程定量模拟一体化的监测评估技术体系,评估了三江源生态保护和建设一期工程的生态成效.结果表明:工程实施8年以来,三江源区宏观生态状况趋好但尚未达到1970s比较好的生态状况,草地持续退化趋势得到初步遏制但难以达到预期"草地植被盖度提高平均20%~40%"的目标,水体与湿地生态系统整体有所恢复,生态系统水源涵养和流域水供给能力提高,区域水源涵养量达到了增加13.20亿m³目标;重点工程区内生态恢复程度好于非工程区,除了气候影响以外,工程的实施对促进植被恢复具有明显而积极的作用;然而,草地退化局面没有获得根本性扭转,工程实施尚未遏制土壤水蚀增加趋势,一期工程局部性和初步性特点突显出三江源区生态保护任务的长期性和艰巨性.

The nexus exploration among land use/land cover change, ecosystem services and human well-being has been increasingly crucial in the context of Future Earth. However, the spatial heterogeneity and the entwining process among these three aspects have not yet been in-depth and systematically explored. Here we identified the spatiotemporal pattern of ecosystem services during the past 20 years in Yushu, the eco-fragile region and the centre of Qinghai-Tibet Plateau, as well as clarified its relationships with land use change and human well-being. We revealed that: (1) The structure of the ecosystem and land use in this area have been increasingly stable, and the ecological projects have exerted a positive impact. (2) Although the ecological environmental issues still need more attention, the ecosystem services of the area have been positively developing. (3) Derived by the ecosystem services increase, environmental projects and policies, the human well-beings of culture and education performed much better than other aspects. (4) It is crucial to carry out long-term ecological projects and increase educational investment for maintaining the stability of this ecologically fragile area. This study provides significant support for the regional ecological sustainability decision making, especially for the Qinghai-Tibet Plateau, the roof of the world.

Relief degree of land surface (RDLS) is one of the key indicators in the fields of suitability assessment of human settlements (SAHS) as well as resources and environmental carrying capacity (RECC) evaluation at the regional scale. Currently, there is still a lack of in-depth research on the determination of the optimal window size for the RDLS calculation and evaluation and its correlation analysis with two topographical parameters, e.g., elevation and relative height difference. These issues further affect the effective representation of the RDLS in the delineation of local to regional topographic relief. Therefore, an objective understanding of the RDLS in the Qinghai-Tibet Plateau of China greatly contributes to promoting the construction of national ecological security barrier and regional green development. In this study, based on the 30 m Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM Version 2), the optimal window size for calculating and evaluating the RDLS in the Qinghai-Tibet Plateau was accurately determined using the average change-point method, and the first 30 m RDLS thematic map for the Qinghai-Tibet Plateau was generated accordingly. Next, the interrelation between the RDLS and elevation and relative height difference was quantitatively examined. Based on that, the effective representation or geographical meanings of the RDLS in the plateau were defined. The results/conclusions include: (1) The optimum window size for the RDLS calculation and evaluation in the study area based on the 30 m GDEM is a rectangular neighborhood of 41×41 pixels, equaling to an area of about 1.51 km2. The average change-point analysis approach shows that the optimum window size for regional RDLS analysis is unique. (2) The average RDLS of the study area is approximately 5.06, along with over 60% of the plateau ranging between 4.5 and 5.7. On the whole, the topographic relief increases from the northeast to the southwest and west parts. Gentle to small-relief landforms are mostly seen in the Qaidam Basin, the Southern Tibet Valley, and the Hehuang Valley (Yellow and Huangshui river valleys). Also, the differences in the local surface relief in varied latitudinal sections (along the mountain range) are small, while those at longitudinal level are big, showing hierarchical and regular fluctuations (crossing the mountain trending). (3) Correlation analyses showed that different values of the RDLS in the plateau correspond to geomorphic units with different elevations and relative height differences. The profile characteristics of the mountains in the Qinghai-Tibet Plateau based on different terrain reliefs indicate that the height above sea level of low mountains steadily increases first, then experiences sudden rise and severe fluctuation in surface relief, and finally forms the orderly ups and downs of the extreme mountains, e.g., the Himalayas.

地形起伏度是区域人居环境适宜性与资源环境承载力的关键评价指标之一。当前有关其最佳评价窗口、及其与海拔—相对高差的相互关系仍缺乏深入研究,进而影响该指标对区域地形起伏的有效表征。客观认识青藏高原地形起伏度有助于促进其国家生态安全屏障建设与区域绿色发展。以先进星载热发射和反射辐射仪全球数字高程模型（ASTER GDEM, 30 m）地形数据（V2）为基础,本文利用均值变点分析法确定了青藏高原地形起伏度评价的最佳分析窗口,基于地形起伏度模型（RDLS）研制了青藏高原首套30 m地形起伏度专题图,据此分析了地形起伏度与海拔、相对高差的相互关系,并界定了地形起伏度对区域地形起伏状况的有效表征。主要结果/结论包括：① 基于GDEM的青藏高原地形起伏度评价最佳窗口为41×41个像元的矩形邻域,对应面积约为1.51 km²,均值变点分析表明区域地形起伏度评价最佳窗口有其唯一性。② 青藏高原地形起伏度均值约为5.06,超3/5区域地形起伏度介于4.5~5.7之间;整体上,青藏高原地形起伏程度由其东北部向西南部、西部递增,仅在柴达木盆地、藏南谷地以及河湟谷地出现低起伏地貌特征。且地表起伏在不同纬度剖面变化较为一致（沿山脉走向）,但不同经度剖面起伏层次错落（横切山脉走向）。③ 相关性分析表明不同地形起伏度分别对应不同平均海拔、不同相对高差的地貌单元。青藏高原地形起伏度经纬向剖面分析表明,该区由东部的低山稳步爬升,山体经历骤然爬升（即地表起伏特征剧烈）后形成以极高山为主的有序错落起伏（喜马拉雅山脉）。

Land-Use/land Cover Changes (LUCC) are a direct consequence of human and nature interactions. China's Land Use/cover Datasets (CLUD) were updated regularly at five-year intervals from the late 1980s to the year of 2010 with standard procedures based on Landsat TM/ETM + images. A dynamic zoning method was proposed to analyze major land-use conversions. The spatiotemporal characteristics, differences, and causes of land-use changes at a national scale were then examined. The main findings are summarized as follows: Land-Use Changes (LUC) across China indicated a significant variation in spatial and temporal characteristics in the past 20 years between the 20th and 21st centuries. The amount of cropland change decreased in the south and increased in the north, but the total area remained almost unchanged. The reclaimed cropland was shifted from northeast to northwest. The built-up lands were expanded rapidly, which were mainly distributed in the east and gradually spread out to the midwest. Woodland decreased first and then increased, but desert area was inverted. Grassland continued decreasing. Different spatial patterns of LUC in China were found between the late 20th century and the early 21st century. The original 13 LUC zones were replaced by 15 units with changes of boundaries in some zones. The main spatial characteristics of these changes included (1) an accelerated expansion of built-up land in the Huang-Huai-Hai region, the coastal areas of southeastern China, the midstream area of the Yangtze River, and the Sichuan Basin; (2) the shifted land reclamation in the north from Northeast China and eastern Inner Mongolia to the oasis agricultural areas in Northwest China; (3) the continuous transform from rain-fed farmlands in Northeast China to paddy fields; and (4) the effectiveness of the “Grain-for-Green” project in the southern agricultural-pastoral ecotones of Inner Mongolia, the Loess Plateau, and mountainous areas of southwestern China. In recent two decades, although climate change in the north impacted the change in cropland, policy regulation and economic driving forces were still the primary causes of LUC across China. During the first decade of the 21st century, the anthropogenic factors that drove variations in land-use patterns have shifted the emphasis from one-way land development to both development and conservation. The "dynamic zoning method" was used to analyze changes in the spatial patterns of zoning boundaries, the internal characteristics of zones, and the growth and decrease of units. The results revealed "the pattern of the change process," namely the process of LUC and regional differences in characteristics at different stages. The growth and decrease of zones during this dynamic LUC zoning, variations in unit boundaries, and the characteristics of change intensities between the former and latter decades were examined. The patterns of alternative transformation between the "pattern" and "process" of land use and the reasons for changes in different types and different regions of land use were explored.

. Land cover (LC) determines the energy exchange, water and carbon cycle between Earth's spheres. Accurate LC information is a fundamental parameter for the environment and climate studies. Considering that the LC in China has been altered dramatically with the economic development in the past few decades, sequential and fine-scale LC monitoring is in urgent need. However, currently, fine-resolution annual LC dataset produced by the observational images is generally unavailable for China due to the lack of sufficient training samples and computational capabilities. To deal with this issue, we produced the first Landsat-derived annual China land cover dataset (CLCD) on the Google Earth Engine (GEE) platform, which contains 30 m annual LC and its dynamics in China from 1990 to 2019. We first collected the training samples by combining stable samples extracted from China's land-use/cover datasets (CLUDs) and visually interpreted samples from satellite time-series data, Google Earth and Google Maps. Using 335 709 Landsat images on the GEE, several temporal metrics were constructed and fed to the random forest classifier to obtain classification results. We then proposed a post-processing method incorporating spatial–temporal filtering and logical reasoning to further improve the spatial–temporal consistency of CLCD. Finally, the overall accuracy of CLCD reached 79.31 % based on 5463 visually interpreted samples. A further assessment based on 5131 third-party test samples showed that the overall accuracy of CLCD outperforms that of MCD12Q1, ESACCI_LC, FROM_GLC and GlobeLand30. Besides, we intercompared the CLCD with several Landsat-derived thematic products, which exhibited good consistencies with the Global Forest Change, the Global Surface Water, and three impervious surface products. Based on the CLCD, the trends and patterns of China's LC changes during 1985 and 2019 were revealed, such as expansion of impervious surface (+148.71 %) and water (+18.39 %), decrease in cropland (−4.85 %) and grassland (−3.29 %), and increase in forest (+4.34 %). In general, CLCD reflected the rapid urbanization and a series of ecological projects (e.g. Gain for Green) in China and revealed the anthropogenic implications on LC under the condition of climate change, signifying its potential application in the global change research. The CLCD dataset introduced in this article is freely available at https://doi.org/10.5281/zenodo.4417810 (Yang and Huang, 2021).

Rainfall erosivity shows the potential ability of the soil loss caused by rainfall and it is very important for predicting soil loss quantitatively. A rainfall erosivity model using daily rainfall amounts to estimate half-month rainfall erosivity directly was established from data of 71 weather stations in China. The average coefficient of determination for all stations was 0.718 and the average relative error estimating the annual average rainfall erosivity was 4.2%. Both parameters of α and β in the model were different in different regions. The parameter α was high correlative with parameter β and parameter β was related to rainfall characteristics, so both parameters could be estimated by using rainfall indexes. With the set of parameter values estimated by using rainfall indexs,the average coefficient of determination decreased to 0.697 and the average relative error estimating the annual average rainfall erosivity increased to 17.3%. The model worked very well in the regions where the rainfall was abundant and the result was on the low side when extreme storm erosivty was estimated. The daily rainfall erosivity model could be used to estimate the annual average rainfall erosivity and its seasonal distribution.

Soil wind erosion is a major ecological environment problem in northern China. Xilingol League is located in the arid and semiarid areas. As one of the areas suffering from most serious wind erosion in northern China, its ecological environment is very fragile. Because of this environmental fragility, the area was included in the Beijing-Tianjin Dust Storms Sources Control Project that was officially approved by The State Council and implemented in 2002. In order to better understand the status of soil erosion and guide the regional desertification prevention, it is necessary to assess the variation of soil erosion and reveal the influences of weather and vegetation on soil erosion in Xilingol. In this study, based on wind speed, temperature, precipitation and other meteorology data, the normalized difference vegetation index, snow coverage and other remote sensing data, the Revised Wind Erosion Equation (RWEQ), which takes Newton's first law of motion as the foundation, was applied to evaluate annual soil losses caused by wind erosion. The results show that: The average soil erosion in Xilingol League between 1990 and 2010 was 0.34 billion tons. The intensity of soil wind erosion is low in most parts of Xilingol—these areas were mainly concentrated in the eastern, central and southern areas, where vegetation coverage is higher, wind erosion forces is lower, and rainfall is abundant. The areas with medium and higher intensity of erosion were mainly distributed in the Hunshandac desert of Suninteyou Banner, Zhengxiangbai Banner and Zhenglan Banner, where the soil is highly prone to wind erosion. Since the 1990s, soil erosion in Xilingol showed a deceasing trend. The reduction of wind erosion intensity is related to the weakened wind energy and improved vegetation cover. Wind erosion forces is the main driving factor of wind erosion—soil erosion was significantly correlated with the wind erosion forces (<i>r</i>=0.95, <i>p</i><0.05). Wind erosion in Xilingol occurred frequently in windy springs. At this time, the effect of soil erosion associated with low vegetation coverage is most significant. Soil erosion was significantly correlated with the spring vegetation coverage in regions of higher wind erosion forces (<i>r</i>>0.7, <i>p</i><0.01). Increased vegetation coverage effectively reduced soil wind erosion of the region in the recent 20 years. Low vegetation coverage makes the prevention of soil erosion more difficult and improving the grassland condition, especially in the spring season, is the key to controlling wind erosion of the soil. The RWEQ model was mainly used in the farmlands of the United States and cannot be directly applied in the grassland areas of China. In order to better apply the model in grasslands, the soil particle content was converted into the US system, surface roughness was measured by the roller chain method and withered vegetation coverage (obtained by photos) was introduced to replace flat residues on the surface of the soil. Even so, more research is needed to solve problems such as the influence of relief on soil wind erosion, the determination of noneroding boundaries, among others.

土壤风蚀是中国北方地区重要的生态环境问题。锡林郭勒盟位于中国干旱、半干旱地区，是中国北方典型风蚀区，其特殊的地理位置又使得本区成为华北重要的生态屏障，为此锡林郭勒盟全区均划入了京津风沙源治理工程区。为了更好地阐明锡林郭勒盟的土壤风力侵蚀过程，指导区域的荒漠化防治，，基于气象、遥感数据，利用RWEQ模型定量分析了20 世纪90 年代以来锡林郭勒盟的土壤风蚀时空格局，揭示土壤风蚀的主要影响因素。研究表明：锡林郭勒盟多年平均土壤风蚀量为3.39 亿t。土壤风蚀强度以微度和轻度为主，主要集中在植被较好，风蚀力较低，降雨量较高，雪被覆盖地表时间较长的东、中部地区以及南部地区。侵蚀强度为中度以上的侵蚀区集中在苏尼特右旗、正镶白旗和正蓝旗的浑善达克沙地；90 年代以来，锡林郭勒盟的土壤风蚀强度总体上呈减弱趋势，主要与风场强度的减弱，植被盖度等的变化有关。土壤风蚀多发生于风蚀力较大的春季，风蚀强度较大区域的春季植被盖度与风蚀量呈显著负相关（r>0.7，p<0.01），且近20 年植被盖度提升有效降低了该区域的土壤风蚀。

Key ecological functional zones provide continuous ecosystem services and play an indispensable role in ensuring national ecological security and social sustainable development. From the perspective of ecosystem service trade-off and synergy, this paper discusses and analyzes the protection characteristics of key ecological functional areas. The data includes multi-source datasets such as ecosystem types, meteorological data, elevation data and soil data from 2000 to 2019. Methods of the dynamic degree of ecological spatial change, ecosystem service model and partial correlation coefficient were used for evaluation and analysis. This research selects the Qinling-Daba (Qinba) Mountains region with high similarity of natural and geographical conditions as the reference unit, takes ecosystem supply services and regulation services as the core content, and analyzes the trade-off and synergy relationship of ecosystem services based on the quantitative analysis of the characteristics of ecological spatial changes from 2000 to 2019. The results showed that the ecological status of the study area gradually improved, and the ecosystem tended to be stable after the delimitation of key ecological functional zones. The service capacity of key ecological functional zones is gradually increasing, and the average net primary productivity, total soil conservation and total water conservation are higher than those outside the key ecological functional zones by 25.95 gC/m2, 5.81×108 t and 24.95×108 m3, respectively. The synergy between soil conservation services and ecosystem supply services was positively correlated with the improvement of ecological status. Due to the impact of precipitation, the synergistic relationship between water conservation services and ecosystem supply services after 2010 became worse. Overall, the designation of key ecological functional areas in the Qinba Mountains has driven the "quantitative growth" of regional ecological space and the "qualitative improvement" of ecosystem services. However, the "synergy" of the relationship between ecosystem services is not obvious, and even changed to "trade-off", which requires the country to make more targeted ecosystem protection and management decisions in the future, and improve the overall benefits of ecosystem and support the sustainable supply of regional ecosystem services.

重点生态功能区提供着源源不断的生态系统服务,在保障国家生态安全和社会可持续发展方面,有着不可或缺的基础作用。但是,以生态系统服务权衡与协同关系为视角,进而探讨分析重点生态功能区保护特征的研究案例相对较少。本文以秦巴重点生态功能区为评估分析区域,选择自然地理条件相似度极高的秦巴山区为参照单元,以生态系统供给服务与调节服务为核心内容,在定量分析2000&#x02014;2019年期间的生态空间变化特征基础上,分析评估生态系统服务权衡与协同关系。结果表明：秦巴山区生态状况逐渐变好,重点生态功能区划定之后,生态系统趋于稳定;重点生态功能区服务能力呈逐渐增强的趋势,平均净初级生产力、土壤保持总量和水源涵养总量比重点生态功能区外分别高出了25.95 gC/m²、5.81亿t和24.95亿m³;土壤保持服务和生态系统供给服务的协同关系与生态状况改善呈正相关;由于受到降水的影响,2010年之后的水源涵养服务与生态系统供给服务的协同关系变差。总体来看,秦巴重点生态功能区的划定带动了区域生态空间&#x0201c;量的增长&#x0201d;和生态系统服务&#x0201c;质的提升&#x0201d;,但生态系统服务之间关系的&#x0201c;协调性&#x0201d;仍然不足,甚至从&#x0201c;协同&#x0201d;转为&#x0201c;权衡&#x0201d;关系,这要求未来国家需要制定更有针对性的生态系统保护管理决策,提高生态系统总体效益,支撑区域生态系统服务的可持续供给。

Vegetation recovery under global change and its consequent evolution of eco-hydrological processes have modulated the water resources conservative capacity in the source region of the Yellow River (YRSR). Based on climatological data, remotely sensed vegetation index and geographical information, the integrated simulations of water and carbon cycles in the YRSR are presented, with the vegetation interface processes (VIP) distributed eco-hydrological dynamic model. Then the co-evolving mechanisms of hydrological and vegetation dynamics are investigated. Results show that warming and wetting climate in the YRSR has improved the vegetation growing condition and extended the growing period for more than 10 days in recent decades. Averaged NDVI from 2010 to 2020 increased by 4.5% relative to that from 2000 to 2009. Vegetation gross primary productivity (GPP) shows a significant uptrend with a rate of 4.57 gC m-2 a-1, 77% of which is contributed by climate change and elevated atmosphere CO2 fertilization, and the rest 23% is by vegetation greening. Evapotranspiration (ET) is increasing at a rate of 2.54 mm a-1 and vegetation water use efficiency (WUE, expressed as GPP/ET) is also improving at a relative rate of 5.1% a-1. Generally, annual ET, GPP and WUE and their trends are decreasing along the elevation below 4200 m. At basin scale, there are significant positive correlations between the vegetation greenness and the runoff coefficient with precipitation in the current and previous years, demonstrating a legacy effect of precipitation for vegetation recovery on water conservation capacity. The increased ET might be a benefit to the water recycle between land surface and atmosphere, which will alleviate the reduced potential of water yield owing to ecological restoration and establish trades-off and synergies among precipitation, vegetation and water yield. Conclusively, exploring the mechanisms of hydrological responses to climate change and vegetation recovery and its feedback will provide scientific support to the assessment of ecological engineering programs in the source regions.

全球变化下黄河源区水文过程的演变影响流域生态系统的水源涵养功能,流域植被改变也影响水循环。本文基于气候、植被信息和VIP分布式生态水文模型,开展黄河源区水碳循环要素变化的集成模拟,分析了气候&#x02014;植被&#x02014;水文要素的协同演变机制。结果表明,2000年以来黄河源区气候呈暖湿化趋势;植被绿度明显提高,2010&#x02014;2019年比2000&#x02014;2009年平均增加了4.5%;生长季延长了至少10 d;植被生产力（GPP）显著上升,倾向率为4.57 gC m^-2 a^-1;植被恢复措施对GPP变化的贡献约为23%,气候变化和大气CO₂升高的施肥效应的贡献为77%。源区植被蒸散量（ET）呈增加趋势,倾向率为2.54 mm a^-1,水分利用效率（WUE）亦提高,平均相对上升率为5.1% a^-1。GPP、ET和WUE年总量及其变化率在海拔4200 m以下随高度上升而减小,之后变化趋缓。源区植被绿度和径流系数与当年和前一年降水呈显著正相关,反映降水蓄存于植物根层土壤的遗留效应。蒸散增强在一定程度上有利于源区地表&#x02014;大气之间的水分再循环,帮助缓解生态恢复引起的产水能力下降,促进降水&#x02014;植被&#x02014;径流之间的良性互馈关系的形成。揭示水文对气候变化和植被恢复的响应和互馈机制,可为生态恢复措施对源区水源涵养功能的影响及效应的定量评估提供科学依据。

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Scientifically assessing the interaction between urbanization and eco-environment in the Tibetan Plateau is critical for optimization of urbanization speed and quality, and for the restoration and improvement of the eco-environment. Based on previous studies about the interaction between urbanization and eco-environment in the Tibetan Plateau, we established complete analysis models to examine the overall process, including comprehensive evaluation index analysis, coupling coordination degree measurement, coupling type identification, decoupling path exploration, and future trend prediction. We used a multi-scale comparison analysis method to clarify the differences between scales (across the Tibetan Plateau and its provinces and prefecture-level cities), identify the problem regions, and propose customized improvement measures. Here we show that the comprehensive evaluation index of urbanization has experienced a staged upward trend in different scales, and the overall urbanization index of Qinghai is higher than that of Tibet. However, the changing trends of the eco-environment index are different. The changes in eco-environment index of Qinghai show a decreasing trend, whereas Tibet's changes tend to be stable. The eco-environment index of prefecture-level cities is stratified. We also found that the changing trends of coupling coordination degree of urbanization and eco-environment in different scales were overall rising. The coupling type has changed from imbalanced recession type to nearly imbalanced recession type, and finally to grudgingly coordinated development type. However, most of these types are lagged urbanization types. The alternate change trend between strong decoupling and weak decoupling indicates a negative interaction between urbanization and the eco-environment at different scales. Thus, it can be inferred that the lagged urbanization is a prominent phenomenon. The result of predication shows that in the next 10 years the coupling coordination degree of urbanization and eco-environment will increase steadily in all geographic units, but there will be a gap in the growth rate.

科学评估青藏高原城镇化与生态环境交互影响的总体状况,对优化城镇化速度和质量,修复和提升生态环境状态具有重要意义。在梳理青藏高原城镇化与生态环境交互影响研究进展基础上,本文尝试构建一套完整的城镇化与生态环境交互影响分析模型体系,实现从综合评价指数分析、耦合协调度量化、耦合类型识别、解耦路径探索到未来趋势预测的全过程解析。以青藏高原及其省域、地级单元多尺度分析对比为手段,尝试厘清尺度之间的差异性,识别出问题区域,并提出针对性的改进措施。研究发现,青藏高原不同尺度间城镇化综合评价指数呈阶段性上升趋势,青海的整体城镇化指数高于西藏;生态环境指数变化趋势不同,青海呈下降态势,西藏则趋向平稳,各地级单元生态环境指数存在分层现象。青藏高原不同尺度城镇化与生态环境耦合协调度总体呈上升趋势,协调类型由失调衰退类向濒临失调衰退类转变,最后转为勉强协调发展类,基本属于城镇化滞后型。城镇化指数与生态环境指数呈现出强脱钩、弱脱钩交互出现的波动态势,说明不同尺度间存在城镇化与生态环境的负相互作用,消极城镇化现象突出。通过预测,青藏高原各地级单元在未来10年内,系统耦合协调度将稳步上升,但各地增长速度将存在显著差距。

Geographically explicit historical land use and land cover datasets are increasingly required in studies of climatic and ecological effects of human activities. In this study, using historical population data as a proxy, the provincial cropland areas of Qinghai province and the Tibet Autonomous Region (TAR) for 1900, 1930, and 1950 were estimated. The cropland areas of Qinghai and the TAR for 1980 and 2000 were obtained from published statistical data with revisions. Using a land suitability for cultivation model, the provincial cropland areas for the 20th century were converted into crop cover datasets with a resolution of 1 × 1 km. Finally, changes of sediment retention due to crop cover change were assessed using the sediment delivery ratio module of the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model (version 3.3.1). There were two main results. (1) For 1950-1980 the fractional cropland area increased from 0.32% to 0.48% and land use clearly intensified in the Tibetan Plateau (TP), especially in the Yellow River-Huangshui River Valley (YHRV) and the midstream of the Yarlung Zangbo River and its two tributaries valley (YRTT). For other periods of the 20th century, stability was the main trend. (2) For 1950-1980, sediment export increased rapidly in the Minhe autonomous county of the YHRV, and in the Nianchu River and Lhasa River basins of the YRTT, which means that sediment retention clearly decreased in these regions over this period. The results of this assessment provide scientific support for conservation planning, development planning, or restoration activities.

Spatialization of human activity intensity is the basis for examining regional differences of human activities and its change process, and it is also the scientific basis for accurately identifying the driving factors of land change and rationally regulating human activities. The current research on human activity intensity mostly uses mathematical methods to spatially assign indirect indicators, which lacks the reflection of the mechanism of human activity and also restricts the display of the spatial heterogeneity of human activity intensity. This paper took grazing activity on the Tibetan Plateau as the research object in an attempt to spatialize grazing intensity. First, based on grazing preferences and grassland management strategies, and from the perspective of grazing mechanism, we proposed a method to distinguish grazing areas and non-grazing areas; then, we used grazing density to measure the overall grazing pressure of grassland, and used grazing probability to describe the spatial difference of grazing pressure. In addition, we developed a spatial model of regional grazing intensity according to grazing density and grazing probability. As a case study, we used this model to spatialize grazing intensity of Zeku County, a typical pastoral area on the Tibetan Plateau, based on township-level animal husbandry data and basic physical geographic information. The results showed that the spatial model of grazing intensity we developed can reflect the spatial characteristics of grazing activity well, and the selection of direct indicators and objective assignment methods improve the accuracy of the spatialization results. It is also found that the results of this paper can more clearly reflected the spatial difference of grazing intensity within the county than the previous research results, and the change process of grazing intensity had a better coupling with the change of NDVI value over the same period. This paper could provide a useful reference for the research on spatialization methods of human activities.

人类活动强度空间化是分析人类活动区域差异及其变化过程的基础,也是准确辨识土地变化驱动因素、合理调控人类活动的科学依据。当前人类活动强度研究多以数理方法对代用指标进行空间化,缺乏对人类活动机理过程的反映,也制约了人类活动强度空间异质性的展现。本文以青藏高原放牧活动为研究对象,在综合放牧喜好和草地管理策略的基础上,从放牧行为机理的角度,提出了区分放牧区与非放牧区的方法;以放牧密度衡量草地整体放牧压力,以放牧概率刻画放牧活动的空间差异,构建了区域放牧强度空间化模型。并以高原典型牧业县&#x02014;泽库县为例,基于乡镇级牧业数据和自然地理基础信息进行了实证研究。结果表明：空间化结果较好反映了泽库县放牧强度的空间特征;直接指标的选取和客观的赋值方法提高了放牧强度空间化结果的准确性;比现有研究结果更能体现出县域内放牧强度的空间差异,且放牧强度变化过程与同期NDVI值变化具有较好的耦合性。本文为人类活动空间化方法研究提供了有益参考。

Being a key ecological security barrier and production base for grassland animal husbandry in China, the balance between grassland forage supply and livestock-carrying pressure in China's pasture regions directly affects grassland degradation and restoration, thereby impacting grassland ecosystem services. This paper analyzes the spatiotemporal variation in grassland vegetation coverage, forage supply, and the balance between grassland forage supply and livestock-carrying pressure in China's pasture regions from 2000 to 2015. We then discuss the spatial pattern of grassland ecological conservation under the impacts of grassland degradation and restoration, and livestock-carrying pressure. Over the last 16 years, the total grassland area in China's pasture regions decreased by 16,000 km2, with vegetation coverage degraded in 6.7% of grasslands but significantly restored in 5.4% of grasslands. The provisioning of forage by natural grassland mainly increased over time, with an annual growth rate of approximately 0.3 kg/hm2, but livestock-carrying pressure also increased continuously. The livestock-carrying pressure index (without any supplementary feeding) reached as high as 3.8. Apart from the potential livestock carrying capacity in northeastern Inner Mongolia and the central Tibetan Plateau, that in most parts of China's pasture regions is currently overburdened. Considering the actual supplementary feeding during the cold season, the livestock-carrying pressure index is about 3.1, with the livestock-carrying pressure mitigated in central and eastern Inner Mongolia. Assuming full supplemental feeding in the cold season, livestock-carrying pressure index will fall to 1.9, thus significantly alleviating pressure in Inner Mongolia and the Tibetan Plateau. Based on these data, we propose different conservation and development strategies to balance grassland ecological conservation and animal husbandry production in different regions, namely nature reserves, pastoral areas, semi-farming and semi-pastoral areas, and farming areas, according to prevailing patterns of grassland ecological protection.

中国草原牧区作为重要生态安全屏障和草地畜牧业生产基地,其草畜平衡状态直接影响草地退化与恢复,进而影响草地生态系统服务能力的强弱。本文分析了2000—2015年主要草原牧区草地植被覆盖、牧草供给、草畜平衡状态的时空变化特征,深入探讨草地退化与恢复及载畜压力下草地生态系统保护与恢复空间格局。结果表明：过去16年主要草原牧区草地面积净减少约163万hm²,6.7%的草地出现植被覆盖退化,而5.4%的草地呈现植被覆盖明显恢复。天然草地牧草供给量以增加为主,年增率约0.3 kg/hm²,然而其载畜压力亦持续增加,不考虑补饲的载畜压力指数高达3.8,除内蒙古东北部、青藏高原中部仍有载畜潜力,其余多处于超载状态;考虑实际冷季补饲的载畜压力指数约3.1,内蒙古中东部有所缓解;假设冷季全额补饲则载畜压力指数减至1.9,内蒙古、青藏高原等区域明显缓解。叠加上述数据,本文针对自然保护地、牧区、半农半牧区和农区等不同区域的草地生态保护格局,提出了平衡草地生态保护与畜牧生产利用的不同发展策略。

In view of the lack of research on the screening and comprehensive evaluation of vegetation ecological parameters based on remotely sensed date products, this paper firstly proposes a method to evaluate the vegetation eco-environmental quality in Tibet by PCA (principal component analysis). Based on five indicators, including fractional vegetation coverage (FVC), leaf area index (LAI), gross primary productivity (GPP), land surface temperature (LST) and modified wet (Wet) from MODIS satellite data, the law and mechanism of spatial-temporal changes of eco-environmental quality in Tibet in the last 10 years are explored. The experimental results show that: (1) The comprehensive quality of the eco-environmental quality in Tibet is relatively fragile, and the spatial difference in eco-environmental quality is significant. It is excellent in the southeast but poor in the northwest. (2) During the period from 2006 to 2016, the eco-environmental quality in Tibet shows a trend of improving overall. In terms of time series, the proportion of areas improved and degraded in the past 10 years was 31.88% and 4.13% respectively. In terms of spatial distribution, the improved areas are distributed in the northwestwen, central and eastern parts, but but the degraded areas are distributed in the southeastern parts. (3) Improvements in hydrothermal conditions (especially the increase in precipitation) and human protection policies have led to improvements in the eco-environmental quality in the western and central Tibet. The strengthening of social and economic activities is the main reason for the deterioration of the eco-environmental quality in the southeast of Tibet.

针对缺少基于遥感数据产品的西藏地区植被生态参数筛选及综合评价的研究现状,以2006年和2016年西藏地区MODIS卫星遥感产品反演得到的植被覆盖度、叶面积指数、植被总初级生产力、区域热度与改进的湿度5项指标为基础,提出了基于主成分分析法的西藏植被生态环境质量评价方法,并探索了其时空变化规律及机理。结果表明：① 西藏地区植被生态质量整体较为脆弱,且区域差异明显,呈现东南优、西北差的分布格局。② 2006-2016年间西藏地区植被生态质量总体呈现变好的趋势。在时间序列上,2006-2016年间改善、退化的区域占比分别为31.88%和4.13%;在空间分布上,变好的区域分布在西北、中部和东部,变差的区域集中在东南部。③ 水热状况改善特别是降水量的增加和人为保护政策使得研究区西部和中部地区生态质量有所提高。社会经济活动加强是研究区东南部生态质量变差的主要原因。