In recent decades, due to the combined effect of human activities and climate change, the ecosystem of our country has been continuously degraded, seriously affecting the sustainable economic and social development. In order to protect and recover the ecosystem, China has invested heavily in launching a series of key ecological programs and projects including North Shelter Forest Program, Grain for Green Project and integrated ecosystem management of rock desertification. How to comprehensively and timely grasp the ecological effects and existing flaws of the implementation of key ecological projects so as to scroll the implementation of ecological projects and ensure the implementation effect of the projects, and promote the follow-up ecological engineering deployment of being scientific and space-oriented is a major imperative for the country. Therefore, the National Key Research and Development Program of China set up the project of “Monitoring and Assessment of Ecological Benefits of Key Ecological Engineering in China”. Through the implementation of this project, we will establish an indicator system for monitoring and evaluating the ecological benefits of key ecological projects, developing various technical systems for monitoring and evaluating the ecological benefits of key ecological projects, quantitatively evaluating the ecological benefits of key ecological projects, and concise the technical approaches to enhancing ecological benefits. We will provide a scientific basis for future planning and management of key ecological projects.

近几十年来,由于人类活动和气候变化的共同影响,我国生态系统持续退化,严重影响经济社会的可持续发展。为了保护和修复生态系统,我国先后投巨资启动了三北防护林体系建设、退耕还林(草)、石漠化综合治理等重大生态工程。如何全面及时地掌握重大生态工程实施的生态成效及存在问题,以便滚动调整生态工程实施方案、保障工程实施效果,并使后续生态工程部署具有科学性和空间针对性,是国家的重大迫切需求。为此,国家重点研发计划“典型脆弱生态恢复与保护研究”设立了“国家重大生态工程生态效益监测与评估”项目。通过项目实施,构建重大生态工程生态效益监测评价指标体系,研发各类重大生态工程生态效益监测评估技术体系及系统,定量评价重大生态工程的生态效益,提出生态效益提升的技术途径,为国家重大生态工程的布局和管理提供科学依据。

In response to ecosystem degradation from rapid economic development, China began investing heavily in protecting and restoring natural capital starting in 2000. We report on China's first national ecosystem assessment (2000-2010), designed to quantify and help manage change in ecosystem services, including food production, carbon sequestration, soil retention, sandstorm prevention, water retention, flood mitigation, and provision of habitat for biodiversity. Overall, ecosystem services improved from 2000 to 2010, apart from habitat provision. China's national conservation policies contributed significantly to the increases in those ecosystem services. Copyright © 2016, American Association for the Advancement of Science.

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.

In order to understand the windbreak and sand fixation effects of the Three-North Shelter Forest Program (TNSFP) in recent 35 years, this paper analyzes the amount change of ecosystem sand fixation caused by climate change and vegetation degradation or restoration in the project region, and then assesses the sand fixation effects of the Program. Based on Landsat MSS, TM/ETM+, and environmental satellite (HJ) images, the spatial-temporal datasets of land cover changes in the project region of TNSFP were analyzed in the periods of mid 1970s, 1990, 2000, 2010, 2015, especially the forest and grassland. Combining the NDVI data of AVHRR and MODIS, the vegetation coverage was estimated, and then the change of vegetation coverage in the 1982-2015 was analyzed. The soil erosion modulus were estimated at the regional scale by applying the soil erosion equation (RWEQ), and then the ecosystem services of windbreak and sand fixation were assessed using indicators of amount and retention rate of windbreak and sand fixation. Then the contribution rate of ecological program and climate change to regional ecosystem change was determined by comparing the indexes under the conditions of average climate and real climate. The results showed that: 1) In the past 35 years, the area of forest was continuously increased and grassland was decreased, especially in the semi-arid sandy area and Loess Plateau. The vegetation coverage increased continuously in the before 20 years, and then decreased in recent 15 years. 2) The soil wind erosion modulus is decreased continuously, and the decreasing rate in recent 15 years is much higher than that in the before 20 years. The decreasing rates were especially obvious in sandy land, grassland, and regions planting trees and grassland. The retention ratio of ecosystem windbreak and sand fixation service also increased continuously, especially in arid desert area. Grassland and sandy land contributed 71% of the total amount of windbreak and sand fixation. However, just 6.6% of forest land, and the contribution of conversion grassland was higher than that of conversion forest. 3) In the TNSFP, the weakening of wind erosion force due to reducing wind, and the vegetation restoration in local areas due to TNSFP and other ecological programs, both resulted in a decrease of soil wind erosion, and accounted for 85%-89% and 11%-15% of the decrease. Winter monsoon in mid-latitude Asian is weakened due to global warming. In the project region of TNSFP, the grassland played the most important role in ecosystem service of windbreak and sand fixation, which accounts for more than 63% of the total area. Therefore, the conservation of grassland and sandy land were significant in project region of TNSFP. Project planning and implementation should focus on the transfer of funds from afforestation to grassland conservation and restoration.

通过分析三北工程区生态系统防风固沙服务量变化,进而评价工程的防风固沙效应。结果表明：① 近35 a,三北工程区林地面积持续增加、草地面积持续减少,特别是半干旱风沙区和黄土高原区。植被覆盖度在前20 a持续增加,近15 a则呈现先下降而后略微增加趋势。②土壤风蚀模数持续减少,近15 a减幅远高于前20 a,沙地、草地、其它类型转林地或转草地区域的减幅尤为明显。生态系统防风固沙服务保有率呈上升态势,干旱荒漠区增幅显著。草地和沙地为工程区生态系统防风固沙服务总量贡献了71%,且转草地区域的贡献高于转林地区域。③ 考虑到植被好转同时受气候变化和人类活动的影响,以风场减弱为主的气候变化导致土壤风蚀力减弱与三北防护林等生态工程对生态系统防风固沙服务变化的贡献率分别介于85%~89%和11%~15%之间。

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 use/cover change is an important theme on the impacts of human activities on the earth systems and global environment change. National land-use changes of China during 2010-2015 were acquired by the digital interpretation method using high-resolution remotely sensed images, i.e. the Landsat8 OLI, and GF-2 remote sensing images. The spatio-temporal characteristics of land-use changes across China during 2010-2015 were revealed by the indexes of dynamic degree model, annual land-use changes ratio, etc. The results indicated that built-up land increased by 24.6×103 km2, while cropland decreased by 4.9×103 km2, and the total area of woodland and grassland decreased by 16.4×103 km2. The spatial pattern of land-use changes in China during 2010-2015 was concordant with that of the period 2000-2010. Specially, new characteristics of land-use changes emerged in different regions of China in 2010-2015. The built-up land in eastern China expanded continually, and the total area of cropland decreased, both at decreasing rates. The rates of built-up land expansion and cropland shrinkage were accelerated in central China. The rates of built-up land expansion and cropland growth increased in western China, while the decreasing rate of woodland and grassland accelerated. In northeastern China, built-up land expansion slowed down continually, and cropland area increased slightly accompanied by the conversions between paddy land and dry land. Besides, woodland and grassland area decreased in northeastern China. The characteristics of land-use changes in eastern China were essentially consistent with the spatial governance and control requirements of the optimal development zones and key development zones according to the Major Function-oriented Zones Planning implemented during the 12th Five-Year Plan (2011-2015). It was a serious challenge for the central government of China to effectively protect the reasonable layout of land use types dominated with the key ecological function zones and agricultural production zones in central and western China. Furthermore, the local governments should take effective measures to strengthen the management of territorial development in future.

土地利用/覆被变化是人类活动对地球表层及全球变化影响研究的重要内容。本文基于Landsat 8 OLI、GF-2等遥感图像和人机交互解译方法,获取的土地利用数据实现了中国2010-2015年土地利用变化遥感动态监测。应用土地利用动态度、年变化率等指标,从全国和分区角度揭示了2010-2015年中国土地利用变化的时空特征。结果表明：2010-2015年中国建设用地面积共增加24.6×10³ km²,耕地面积共减少4.9×10³ km²,林草用地面积共减少16.4×10³ km²。2010-2015年与2000-2010年相比,中国土地利用变化的区域空间格局基本一致,但分区变化呈现新的特征。东部建设用地持续扩张和耕地面积减少,变化速率有所下降;中部建设用地扩张和耕地面积减少速度增加;西部建设用地扩张明显加速,耕地面积增速进一步加快,林草面积减少速率增加;东北地区建设用地扩展持续缓慢,耕地面积稳中有升,水旱田转换突出,林草面积略有下降。从“十二五”期间国家实施的主体功能区布局来看,东部地区的土地利用变化特征与优化和重点开发区的国土空间格局管控要求基本吻合;中部和西部地区则面临对重点生态功能区和农产品主产区相关土地利用类型实现有效保护的严峻挑战,必须进一步加大对国土空间开发格局的有效管控。

The impact of land use change on runoff is one of the key concerns in water cycle research. The Yangtze River Basin is the largest river basin in China, and land use change and its impact on runoff are key research questions for runoff variation and flood and drought hazards analyses of the basin. This study used land use data of the Yangtze River Basin in 1980, 1990, 1995, 2000 and 2005 to calculate the dynamic degree, swapping variable values, and other indexes between the four periods by land use transition matrix, evaluated spatial and temporal variation characteristics of land use, and identified key regions of change and driving factors in the basin. Based on the widely-used precipitation-runoff relationship of the Soil Conservation Service (SCS) model, runoff impacts caused by land use change were assessed. The results show that from 1980 to 2005, land transfer activity was more intense in the first (1980-1990) and the fourth (2001-2005) periods compared to the two periods in between (1991-1995, 1996-2000). The middle and upper reaches around Sichuan Province and to its north were the most active regions. Paddy land, dry land, woodland, and grassland areas changed slightly, less than 8%. Influenced by different approaches of environmental protection and economic development in the four periods, cultivated lands (paddy land and dry land) showed inverse changes with grassland, and water body, unused land, and urban land changed to a much greater extent. In particular, due to rapid urbanization, urban land increased by 196.58%. Land use change directly resulted in the increase of average runoff coefficient, which ranged from -0.67%~0.80%, with the mean of 0.05%. The most obvious changes were in highly urbanized regions, particularly around the Yangtze River Delta region. Increase of runoff coefficient would raise the occurrence probability of flooding.

土地利用变化的径流效应是水循环研究中的重点内容之一。长江流域是中国最大的流域,土地利用变化及其径流效应分析是研究该流域径流演变、水旱灾害的基础。本文利用1980、1990、1995、2000、2005年五期土地利用数据,采用土地利用转移矩阵计算土地利用动态度、交换变量等指标,评价了长江流域土地利用的时空变化特征,识别关键变化区域及其变化原因。在此基础上,利用SCS模型的降水—径流方程,分析了土地利用变化的径流效应。研究结果表明：1980-2005年时期,长江流域土地转移活跃程度在第一(1980-1990年)和第四(2001-2005年)时期内明显高于1991-1995年和1996-2000年,中上游四川及其北部地区的活跃程度最大。1980-2005年期间水田、旱地、林地和草地面积变化幅度都在8%以内。但受不同时期环境保护和经济发展因素影响,耕地(水田和旱地)和林地、草地呈现相反的变化,而水域、未利用地和城镇用地相对变化较大;其中快速的城镇化导致城镇用地增幅最高,可达196.58%。土地利用变化直接导致流域的平均径流系数变大,变幅从-0.67%到0.80%,平均增幅0.05%,变化最显著的地区在城市化水平较高的长三角一带。径流系数的增加导致洪水发生的可能性增大。