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Reconstructing forest and grassland cover changes in China over the past millennium

Science China Earth Sciences 2025年第1期68卷 94-110页

作者： Fanneng HE Fan YANG Yafei WANG key laboratory of land Surface Pattern and simulation Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences key Research Institute of Yellow River Civilization and Sustainable Development Henan University University of Chinese Academy of Sciences

Historical forest and grassland cover changes not only are critical indicators for quantifying ecological and environmental change processes but also serve as fundamental data for long-term climate change simulations and terrestrial ecosystem carbon emission assessments. However, because of limitations in historical data, quantitative estimations and spatially gridded reconstructions of these changes remain challenging, necessitating further methodological exploration. This study focused on China's present-day land area over the past millennium, objectively capturing the characteristics and drivers of forest and grassland cover changes. On this basis, using the forest transition theory and the space-for-time substitution method, we depicted the historical deforestation process as an inverted “S” curve and developed a model to reconstruct historical forest area changes based on the functional relationship between the forest area and population size dynamics. Subsequently, a gridded forest allocation model was established on the basis of deforestation tendencies. For the grassland cover, we implemented regionspecific methods, such as the cropland area deduction method and the habitat constraint method, to quantitatively reconstruct historical changes. Consequently, we obtained provincial forest and grassland area changes over the past millennium and mapped 10-km-resolution gridded data of forest and grassland cover. The results indicated the following.(1) The methods developed using population data as a proxy objectively reproduced the spatiotemporal evolution of forest and grassland cover in China over the past millennium. These feasible methods offer a novel pathway for the quantitative reconstruction of historical forest and grassland cover changes.(2) The data indicated that China's forest area generally decreased over the past millennium, characterized by a “decrease-then-increase” pattern. The forest area experienced three distinct phases: a slow decline(AD 1000

关键词： land use and land cover change Forest Grassland Quantitative reconstruction Gridded reconstruction China historical period

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Wetland and habitat dynamics in the evolving landscape of the Middle Yangtze River Basin

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Journal of Geographical Sciences 2025年第1期35卷 88-111页

作者： YANG Peng SUN Kaiya ZHU Yanchao XIA Jun HUANG Heqing SONG Jingxia SHI Xiaorui LU Xixi Hubei key laboratory of Regional Ecology and Environmental Change School of Geography and Information Engineering China University of Geosciences Department of Geography National University of Singapore State key laboratory of Water resources and Hydropower Engineering Science Wuhan University

Wetlands play a critical role in the global environment. The Middle Yangtze River Basin(MYRB), known for its abundant wetland resources, has experienced notable changes resulting from the complex interplay of environmental factors. Therefore, we investigated the spatiotemporal characteristics of wetland ecological quality in the MYRB from 2001 to *** the random forest(RF) regression algorithm and patch-generated land-use simulation(PLUS) model, we forecasted variations in wetland habitat quality and their determinants under the Shared Socioeconomic Pathway-Representative Concentration Pathway(SSPRCP) framework from 2035 to 2095. The main findings are as follows:(1) The RF algorithm was optimal for land-use and land-cover(LULC) classification in the MYRB from 2001 to 2020,when notable changes were observed in water bodies and buildings. However, the forested area exhibited an increase and decrease of 3.9% and 1.2% under the SSP1-2.6 and SSP5-8.5 scenarios, respectively, whereas farmland exhibited a diminishing trend.(2) Wetlands were primarily concentrated in the central and eastern MYRB, with counties in the southwest exhibiting superior ecological-environmental quality from 2001 to 2020. Notably,wetland coverage revealed significantly high level, significant changes, frequent but relatively minor changes under the SSP1-2.6, SSP2-4.5, and SSP 5-8.5 scenarios, respectively.(3)Regions with lower habitat quality were primarily concentrated in urbanized areas characterized by frequent human activities, indicating a clear degradation in habitat quality across different scenarios. In conclusion, we established a foundational framework for future investigations into the eco-hydrological processes and ecosystem quality of watersheds.

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The shifts of precipitation phases and their impacts

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Science China Earth Sciences 2025年

作者： Xuemei LI Tao CHE Yuanlong TANG Huan'e DUAN Guigang WANG Xu ZHANG Chuanming YANG Jun WU Yue ZHANG Lanhai LI Faculty of Geomatics Lanzhou Jiaotong University National-Local Joint Engineering Research Center of Technologies and Applications for National Geographic State monitoring key laboratory of Science and Technology in Surveying & Mapping Gansu Province key laboratory of Cryospheric Science and Frozen Soil Engineering Heihe Remote Sensing Experimental Research StationNorthwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Xinjiang key laboratory of Water Cycle and Utilization in Arid Zone Xinjiang Institute of Ecology and Geography Chinese academy of Sciences Tianshan Snow Cover and Avalanche Observation and Research Station of Xinjiang

Precipitation comes in various phases, including rainfall, snowfall, sleet, and hail. Shifts of precipitation phases, as well as changes in precipitation amount, intensity, and frequency, have significant impacts on regional climate, hydrology,ecology, and the energy balance of the land-atmosphere system. Over the past century, certain progress has been achieved in aspects such as the observation, discrimination, transformation, and impact of precipitation phases. Mainly including:since the1980s, studies on the observation, formation mechanism, and prediction of precipitation phases have gradually received greater attention and reached a certain scale. The estimation of different precipitation phases using new detection theories and methods has become a research focus. Avariety of discrimination methods or schemes, such as the potential thickness threshold method of the air layer, the temperature threshold method of the characteristic layer, and the near-surface air temperature threshold method,have emerged one after another. Meanwhile, comparative studies on the discrimination accuracy and applicability assessment of multiple methods or schemes have also been carried out simultaneously. In recent years, the shift of precipitation from solid to liquid (SPSL) in the mid-to-high latitudes of the Northern Hemisphere has become more pronounced due to global warming and human activities. It leads to an increase in rain-on-snow (ROS) events and avalanche disasters, affecting the speed, intensity, and duration of spring snow-melting, accelerating sea ice and glacier melting, releasing carbon from permafrost, altering soil moisture, productivity, and phenological characteristics of ecosystems, and thereby affecting their structures, processes, qualities, and service functions. Although some progress has been made in the study of precipitation phases, there remains considerable research potential in terms of completeness of basic data, reliability of discrimination schemes,

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Interaction of land Demand and Supply Effects in Intensive land Use: a simulation Study for Chengdu,China

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Journal of Donghua University(English Edition) 2015年第4期32卷 636-641页

作者：辜寄蓉陈先伟江浏光艳杨海龙于有翔 key laboratory of land resources Evaluation and monitoring in Southwest The Bureau of land and resources of Chengdu

Intensive land use( ILU) policies affect the demand and supply of land. These policies promote efficient land use, and demands for land must therefore be evaluated in terms of the level of land-use intensity. If the demand is considered excessive, ILU policies act like a "valve"to restrict the land supply. Drawing on data from Chengdu,China,where developable land is scarce,we construct a model using system dynamics( SD) to simulate two scenarios: ILU development and non-ILU development. The results show that when ILU leads to positive land-use efficiency,land supply will exceed demand,resulting in an appropriate level of real demand for the current population level and GDP. Thus,artificial demand( inflated by investors) is reduced. By contrast,when non-ILU leads to negative land-use efficiency,land demand will exceed supply. In this scenario,artificial demand is higher than real demand.

关键词： land demand and supply intensive land use(ILU) developable land land area system dynamics(SD)

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Unsupervised GRNN flood mapping approach combined with uncertainty analysis using bi-temporal Sentinel-2 MSI imageries

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International Journal of Digital Earth 2021年第11期14卷 1561-1581页

作者： Qi Zhang Penglin Zhang Xudong Hua School of Remote Sensing and Information Engineering Wuhan UniversityWuhanPeople’s Republic of China key laboratory of urban land resources monitoring and simulation Ministry of Natural ResourcesShenzhenPeople’s Republic of China

Floods occur frequently *** timely,accurate mapping of the flooded areas is an important ***,an unsupervised approach is proposed for automated flooded area mapping from bitemporal Sentinel-2 multispectral images in this ***,spatial–spectral features of the images before and after the flood are extracted to construct the change magnitude image(CMI).Then,the certain flood pixels and non-flood pixels are obtained by performing uncertainty analysis on the CMI,which are considered reliable classification ***,Generalized Regression Neural Network(GRNN)is used as the core classifier to generate the initial flood ***,an easy-toimplement two-stage post-processing is proposed to reduce the mapping error of the initial flood map,and generate the final flood *** from other methods based on machine learning,GRNN is used as the classifier,but the proposed approach is automated and unsupervised because it uses samples automatically generated in uncertainty analysis for model *** of comparative experiments in the three sub-regions of the Poyang Lake Basin demonstrate the effectiveness and superiority of the proposed ***,its superiority in dealing with uncertain pixels is further proven by comparing the classification accuracy of different methods on uncertain pixels.

关键词： Unsupervised flood mapping optical remote sensing image spatial–spectral feature extraction uncertainty analysis GRNN Sentinel-2

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Holdout Problem and Its Governance in Market-Oriented urban Renewal: Taking Shenzhen as an Example

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China City Planning Review 2019年第2期28卷 52-59页

作者： Ouyang Yifan Du Jingshen Jin Xiangmu Liu Jinxin(译) School of Public Administration Zhejiang UniversityKey Laboratory of Urban Land Resources Monitoring and SimulationMinistry of Land and ResourcesHangzhouP.R.China Shenzhen Digital City Engineering Research Center Key Laboratory of Urban Land Resources Monitoring and SimulationMinistry of Land and ResourcesShenzhenP.R.China 不详

This paper studies the occurrence, characteristics, and governance mechanism of the holdout problem during market-oriented urban renewal in Shenzhen after a related foreign experience analysis, through methodologies of logical analysis and case *** results indicate that the holdout problem is almost an inevitable result of market-oriented urban renewal, and its proliferation not only goes against social morality and the principle of justice, but also harms social public interests, and even causes market *** paper proposes two approaches to dealing with holdout problem: first, to introduce the contracting commitment to restrict the owners’ freedom of contract, and to guarantee the public benefit of all owners;second, to introduce land expropriation right to regulate holdout behavior via authority of state.

关键词： market orientation urban renewal holdout problem compulsory contracting system expropriation right

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Relationships between climate change, agricultural development and social stability in the Hexi Corridor over the last 2000 years

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Science China Earth Sciences 2019年第9期62卷 1453-1460页

作者： Yanpeng LI Quansheng GE Huanjiong WANG Haolong LIU Zexing TAO key laboratory of land Surface Pattern and simulation Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences

This case study of the Hexi Corridor, Northwestern China, utilizes statistical methods to estimate quantitatively the interaction at a regional level between climate change, ancient social developments, and political coping strategies over the past 2000 years. The data is sourced from high-resolution reconstructions of climate series(temperature and precipitation), and historical records of cultivated land, war, population, and changes in regional administrative systems. The results show that moisture conditions played a more significant role than temperature in driving land reclamation in the Hexi Corridor. Analysis also showed a negative correlation between war frequency and the area of cultivated land in the Corridor over 20-year time intervals. Population growth was found to have a significant positive correlation with the cultivated land area during the study period. The results indicate that a climate-induced decline in agricultural production and the subsequent fluctuations in population could act as a trigger for social unrest, which is especially true at the mutual decadal time-scales. However, the interaction with administrative reform also suggests that, in the face of social and economic turmoil, a reasonable administrative hierarchy could strengthen the social governance of regional government, and promote social stability and economic development at a regional level. The study substantiates this notion with empirical quantitative evidence.

关键词： Climate change Agricultural development Social stability Regional administrative reform Hexi Corridor

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An event-driven dynamic updating method for 3D geo-databases

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Geo-Spatial Information Science 2016年第2期19卷中插5-中插5,140-147页

作者： Han Guo Weixi Wang Zhihan Lv Chen Wu Weiping Xu Shenzhen Research Center of Digital City Engineering ShenzhenChina key laboratory of urban land resources monitoring and simulation Ministry of Land and ResourcesShenzhenChina Shenzhen Institutes of Advanced Technology Chinese Academy of SciencesShenzhenChina State key laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhanChina

With the rapid development of 3D Digital City, the focus of research has shifted from 3D city modeling and geo-database construction to 3D geo-database service and maintenance. The frequent modifications on geometry, texture, attribute, and topology present a great challenge to the 3D geo-database *** article proposes an event-driven spatiotemporal database model (ESDM) that combines the historical and present 3D city models with the semantic classification and state expression, triggered by changing events predefined. In addition, a corresponding dynamic updating method based on adaptive matching algorithm is presented to perform the dynamic updating operation for the complex 3D city models automatically, according to the compound matching of semantics, attributes, and spatial locations. finally, the validity and feasibility of the proposed ESDM and its updating method are demonstrated through a 3D geo-database with more than 1.5 million 3D city models.

关键词： Dynamic updating 3D geo-database semantic event-driven adaptive matching

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Spatial variability and long-term change in pollen diversity in Nam Co catchment(central Tibetan Plateau): Implications for alpine vegetation restoration from a paleoecological perspective

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Science China Earth Sciences 2018年第3期61卷 270-284页

作者： LI Quan key laboratory of land Surface Pattern and simulation Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences

Pollen diversity offers abundant clues into the floristic diversity and history of vegetation change. Few palynological studies investigated modem pollen diversity or the past floristic diversity on the Tibetan Plateau （TP）. Based on modem pollen assemblages from 37 topsoils and 63 surface lake sediments in the Nam Co catchment on the central TP, this study quantitatively explored spatial distribution of modem pollen diversity using Shannon-Wiener index （H） and palynological richness （E（Tn）, n=600）. Pollen diversity indices showed spatial variability among vegetation types, reflecting the differences in terrestrial floristic diversity in the lake catchment. Their values were high in the southeastern region of the lake catchment which is covered by alpine steppe, while values were low for alpine meadow and marsh meadow. The pollen diversity in lacustrine pollen assemblage could be an effective proxy to document past floristic diversity. The past floristic diversity in the lake catchment, recovered from a fossil pollen record ofNMLC-1, showed a long-term change of ascending overlaid by several rapid diversity changes during the last 8400 years due to the downward shift of altitudinal vegetation belt driven by a general climatic cooling. The results imply that under the environmental challenge of climate warming and vegetation degradation, alpine vegetation restoration in the Nam Co catchment and the central TP should pay attention to altitudinal vegetation belt and zonal vegetation of alpine steppe, and use the long-term change of floristic diversity as a historical analogue.

关键词： Pollen diversity Palynological richness Vegetation restoration Nam Co Lake Tibetan Plateau

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Modern pollen assemblages from surface lake sediments in northwestern China and their importance as indicators of vegetation and climate

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Science China Earth Sciences 2015年第9期58卷 1643-1655页

作者： QIN Feng ZHAO Yan LI Quan CAI MaoTang key laboratory of land Surface Pattern and simulation Institute of Geographic Sciences and Nature Resources ResearchChinese Academy of Sciences

The modern pollen assemblages of surface lake sediments and topsoils in northwestern China were studied to understand the relationship of modem pollen data with contemporary vegetation and climate, and the differences between the pollen assem- blages of surface lake sediments and topsoils. The results show that Chenopodiaceae and Artemisia are dominant elements in the pollen assemblages of northwestern China. Additionally, Ephedra, Cyperaceae, Asteraceae, Poaceae, Picea, Pinus, and Betula are also important pollen taxa. Both pollen assemblages and principal component analysis indicate that pollen data from surface lake sediments and topsoils can be used to differentiate the main vegetation types of this region （desert, steppe, mead- ow and forest）. However, differences exist between modern pollen assemblages of the two types of sediments due to the dif- ferent relevant source areas of pollen and degrees of pollen preservation. For example, the larger relevant source area of sur- face lake sediment results in a higher abundance of Betula in pollen assemblage from surface lake sediment, whereas the ten- dency to disintegrate thin-walled pollen types in topsoil leads to a higher proportion of resistant pollen, such as Asteraceae. Linear regression analysis indicates that the Artemisia/Chenopodiaceae （A/C） ratio in pollen assemblages of surface lake sedi- ments can be used to indicate humidity changes in the study area. However, the A/C ratio in topsoils should be used carefully. Our results suggest that pollen data from surface lake sediments would be better references for interpreting the fossil pollen assemblages of lake cores or lacustrine profiles.

关键词： modern pollen assemblage surface lake sediment topsoil vegetation climate northwestern China

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