With the increasing number of remote sensing satellites,the diversification of observation modals,and the continuous advancement of artificial intelligence algorithms,historically opportunities have been brought to th...With the increasing number of remote sensing satellites,the diversification of observation modals,and the continuous advancement of artificial intelligence algorithms,historically opportunities have been brought to the applications of earth observation and information retrieval,including climate change monitoring,natural resource investigation,ecological environment protection,and territorial space planning.Over the past decade,artificial intelligence technology represented by deep learning has made significant contributions to the field of Earth observation.Therefore,this review will focus on the bottlenecks and development process of using deep learning methods for land use/land cover mapping of the Earth’s surface.Firstly,it introduces the basic framework of semantic segmentation network models for land use/land cover mapping.Then,we summarize the development of semantic segmentation models in geographical field,focusing on spatial and semantic feature extraction,context relationship perception,multi-scale effects modelling,and the transferability of models under geographical differences.Then,the application of semantic segmentation models in agricultural management,building boundary extraction,single tree segmentation and inter-species classification are reviewed.Finally,we discuss the future development prospects of deep learning technology in the context of remote sensing big data.展开更多
Climate change and human interference play significant roles on dynamic of water body abundance,and drive related hydrological,biochemical and social/economic processes.Documenting and monitoring surface water area wi...Climate change and human interference play significant roles on dynamic of water body abundance,and drive related hydrological,biochemical and social/economic processes.Documenting and monitoring surface water area with high resolution multi-temporal satellite imagery provide new perspective to evaluate the dynamics of surface water area,especially in continental and global scale.In this study,based on the Landsat images from 1980 s to 2015,we surveyed the spatial and temporal variation of surface water area,including rivers,lakes and reservoirs,in 10-yr temporal slice across China.Furthermore,the driving forces of the variation has been identified to reveal the interaction of water bodies and the changing environment.The results show that,the water surface area expanded over all three decades with strong spatial and temporal difference,despite the drier and warmer climate background;although lakes comprise the largest portion of the surface water area,the highest contributor of surface water expansion was new constructed reservoir located in the densely populated region;climatic parameters alteration,like precipitation and temperature,resulted in the water surface expansion in the northwestern basin by growing water input linked with rain and glacier melting;in the rest part of China,rise of water surface area was predominately attributed to human relocation of water resource,which yielded more new water storage area than the disappeared water body caused by less precipitation and stronger evapotranspiration.The conclusions highlight the integrative water resource management,especially in water conservation and restoration.展开更多
Water resources play a fundamental role in maintaining ecosystem well-being and supporting socio-economic progress.Nevertheless,the water sustainability confronts unprecedented challenges exacerbated by climate change...Water resources play a fundamental role in maintaining ecosystem well-being and supporting socio-economic progress.Nevertheless,the water sustainability confronts unprecedented challenges exacerbated by climate change and human interventions.This research establishes a comprehensive evaluation framework aligned with the United Nations'Sustainability Development Goals(SDGs)to assess water sustainability across 30 Chinese provinces,municipalities,and autonomous regions(excluding Xizang,Hong Kong,Macao and Taiwan).By integrating natural,economic,and social factors,this research elucidated the spatiotemporal evolution patterns of water sustainability from 2010 to 2020,and projected future trajectories under diverse socio-economic pathways(SSPs)for 2030 and 2050.The main findings include:1)China's water sustainability demonstrated gradual improvement during 2010–2020,yet baseline levels remain suboptimal for achieving SDG targets in 2030.Projections suggest significant enhancements by 2050,particularly under the SSP1-2.6 sustainability-oriented scenario.2)Persistent regional disparities are evident,with acute sustainability deficits observed in densely populated,intensively cultivated northern and the arid northwestern territories.These disparities are projected to attenuate by 2050.3)Natural ecological processes emerge as the dominant contributor to water sustainability,with projected growth potential.Economic processes constitute a secondary driver,while social dimensions exhibit more limited influence,both displaying heterogeneous developmental trajectories.4)SDG 6.4(Water Use Efficiency)demonstrates the highest implementation efficiency,whereas SDG 6.3(Water Quality)and SDG 15.1(Terrestrial Ecosystem Conservation)require urgent policy interventions.This study demonstrates the applicability of the proposed SDGs-aligned framework in diagnosing China's water sustainability challenges,providing actionable insights for regional policy prioritization.The interdisciplinary methodology bridges scientific analysis and governance strategies,enabling robust decision-making under complex future uncertainties.展开更多
Ecosystem services in urban agglomerations are the environmental conditions under which human survival and development are sustained.Quantitative assessment of ecosystem services and complex interactions can contribut...Ecosystem services in urban agglomerations are the environmental conditions under which human survival and development are sustained.Quantitative assessment of ecosystem services and complex interactions can contribute positively to the achievement of the Sustainable Development Goals(SDGs)for urban agglomerations.However,studies on the future contribution of multi-scenario ecosystem services to the SDGS are lacking.We pronovel integrated modeling framework that integrates the CLUES,InVEST,SOM,and GWR approaches to address the complex relationship between ecosystem services over a long“past-present-future”time series.We construct a novel ecosystem service bundle-based approach for measuring urban agglomerations progress towards achieving ecologically relevant sustainable development goals at multiple scales.In the future scenario,the water yield(WY),habitat quality(HQ),and soil conservation(SC)show similar spatial patterns,with comparable spatial grids,while carbon stock(CS)remains predominantly unchanged and the ecological protection scenario(EPS)improves more significantly.The high-synergy regions are mainly distributed in bundle 4,and most of the trade-off regions appear in bundles 1 and 2.Over the last 30 years,all but the water-related SDGs are declining in bundle 1 of the two urban agglomerations,which are 15%higher in the Guangxi Beibu Gulf(GBG)than in the Guangdong-Hong Kong-Macao Greater Bay Area(GBA).From 2020 to 2035,the three scenarios demonstrate that the optimization of the SDGs progresses most effectively under the future ecological protection scenario(EPS).In particular,bundles 3 and 4 are significantly improved.This critical new knowledge can be used in sustainable ecosystem management and decision-making in urban agglomerations.展开更多
Wetlands offer important ecological functions and values.Wetland functional zoning provides a reference and basis for sustainable fulfilment and management.In this study,two coastal urban agglomerations in South China...Wetlands offer important ecological functions and values.Wetland functional zoning provides a reference and basis for sustainable fulfilment and management.In this study,two coastal urban agglomerations in South China were taken as study areas,namely,the Guangxi Beibu Gulf(GBG)and Guangdong-Hong Kong-Macao Greater Bay Area(GBA).Based on multisource information data,a wetland functional zoning system was constructed with the four levels of zoning concept,zoning principle,zoning basis,and zoning scheme.The functional zoning and dynamic analysis of wetlands from 1990 to 2020 were carried out from multiple perspectives of wetland ecological functions,wetland management and conservation functions.The results showed that:1)in terms of wetland ecological functions,the two coastal urban agglomerations were dominated by hydrological regulation and purification of environmental functional areas.The coastal region was largely characterized by the main functional areas of climate regulation and biodiversity maintenance.2)Regarding wetland management and conservation functions,two coastal urban agglomerations exhibited similar trends in terms of the sizes of their conservation and buffer zones from 1990 to 2020.Prevention and control zones were mainly located in core cities in a concentrated manner.Conservation zones largely comprised mountainous woodlands and important wetlands.3)The two coastal urban agglomerations could be divided into 21 wetland functional zones.The central river area has remained the main prevention and control zone for many years.Regarding conservation zones,ecological protection and restoration should be the main focus.Regarding buffer zones,the construction of wetlands and surrounding complex systems should be strengthened or enhanced.Regarding prevention and control zones,activities that do not affect wetland functions should be allowed,provided that they comply with existing laws and regulations.This study could provide technical support and practical application guidance for wetland regulation and management.展开更多
Ozone production sensitivity is widely used to reveal the chemical dominant precursors of urban ozone rise.Here,we diagnose the impact of the decline in global human production activities level caused by the COVID-19 ...Ozone production sensitivity is widely used to reveal the chemical dominant precursors of urban ozone rise.Here,we diagnose the impact of the decline in global human production activities level caused by the COVID-19 on ozone sensitivity through the ratio of formaldehyde(HCHO)and NO_(2)(FNR=HCHO/NO_(2))observations from the TROPOspheric Monitoring Instrument.We use a relative uncertainty threshold to clean the satellite FNR,and our satellite FNR present a good correlation(R=0.6248)with U.S.Environmental Protection Agency observations.We found that the outbreak of the COVID-19 did not change the pattern of global ozone sensitivity,while the global regimes was transforming or strengthening to VOC-limited regimes due to the significant decline of human production activities levels.During the COVID-19,ozone sensitivity in Eastern China and East Africa continued to shift to VOC-limited regimes,while India,Western Europe and North America first moved to NOx-limited regimes,and then changed to VOC-limited regimes with the resumption of production and the increase in travel.The clustering results tell that urban ozone sensitivity tends to shift towards NOx-limited regimes as economic growing.The ozone formation in cities with lower FNR and per capita gross domestic product(GDP)are more sensitive to changes in VOCs,while cities with higher FNR and per capita GDP are more sensitive to variations in NOx.Cities with intermediate FNR and GDP are good evidence of the existence of transitional regimes.Our study identifies the driving role of urban economics in orienting the evolution of ozone sensitivity regimes.展开更多
Net primary productivity （NPP） and evapotranspiration （ET） are two key variables in the carbon and water cycles of terrestrial ecosystems. In this study, to test a newly developed NPP algorithm designed for H J-1 ...Net primary productivity （NPP） and evapotranspiration （ET） are two key variables in the carbon and water cycles of terrestrial ecosystems. In this study, to test a newly developed NPP algorithm designed for H J-1 A/B data and to evaluate the usage of HJ-1 A/B data in the quantitative assessment of environments, NPP and ET in Jinggangshan city, Jiangxi province, are calculated using H J-1 A/B data. The results illustrate the following： （1） The NPP and ET in Jinggangshan city in 2olo both show obvious seasonal variation, with the highest values in summer and the lowest values in winter, and relatively higher values were observed in autumn than in spring. （2） The spatial pattern indicates that the annual NPP is high in the southern area in Jinggangshan city and low in the northern area. Additionally, high NPP is distributed in forests located in areas with high elevation, and low NPP is found in croplands at low elevations. ET has no significant north-south difference, with high values in the southeast and northwest and low values in the southwest, and high ET is distributed in forests at low elevations in contrast to low ET in forests in high-elevation areas and in cropland and shrub grassland in low-elevation areas. （3） Compared to the MODIS product, the range of H J-1 NPP is larger, and the spatial pattern is more coincident with the topography. The range of H J-1 ET is smaller than that of the MODIS product, and ET is underestimated to some extent but can reflect the effect of topography. This study suggests that the algorithm can be used to estimate NPP and ET in a subtropical monsoon climate if remotely sensed images with high spatial resolution are available.展开更多
As one of the few ecological wetlands in North China,Baiyangdian bears multiple important ecological functions,including ①adjusting the ecological balance of North China;②safeguarding the downstream areas,especially...As one of the few ecological wetlands in North China,Baiyangdian bears multiple important ecological functions,including ①adjusting the ecological balance of North China;②safeguarding the downstream areas,especially Tianjin City,the Beijing-Shanghai Railway and Huabei Oil Field;③serving as the reservoir for the North-to-South Water Diversion Project and the emergent use of water for Beijing;④conserving biodiversity.Wetland ecotourism is a scientific and wise use pattern for wetland resources,through which,a source of financing is provided for wetland conservation,economic alternatives are generated for local people to reduce overexploitation on wetland resources and the public awareness of environmental protection is enhanced.Since wetland ecotourism can benefit the co-existence between human and nature and promote social equity between people,it enjoys broad promise for popularization and implementation.The proactive cooperation and sound interaction between main stakeholders,and the wide participation of the community residents,will guarantee the sustainable development of wetland ecotourism.Based on the analysis of current status of participation and interactive relationships of the main stakeholders in Baiyangdian tourism,this article made an attempt to apply the theory of participatory development to the ecotourism initiatives of Baiyangdian wetland,discussed and brought forward the countermeasures to improve community participation in wetland ecotourism under the guidance of this theory.展开更多
Increasing populations are causing an increase in food demands, and the area of cultivated land expands every year. Inappropriate land transition from ecology to production results in the constant decline of the ecolo...Increasing populations are causing an increase in food demands, and the area of cultivated land expands every year. Inappropriate land transition from ecology to production results in the constant decline of the ecological security level and influences the regional sustainable development. Adjusting unreasonable land use mode and reconstructing natural land cover are important ways to maintain and improve the ecological environment. Also reclaiming farmland as areas for forests and grasslands (FRFG) is another way. Successful implementation of FRFG in China is the result of comprehensive effect of the multi-scales driving forces. This paper analyses the driving forces of FRFG in China on a national (country) –regional (province) – local (county) – household (farmer) level scale, and the results are: driving forces at the national scale include ecological and food security and the western development of China; at the regional scale, ecological and economic benefits become the main factors to influence the dimension of FRFG under the same policy. The driving forces can be divided into 6 types: industrial structure adjustment, water source protection, flood prevention, the Three-Gorge Project protection, reduction of the amount of sediment flowing into the Yellow River and wind erosion desertification prevention. The driving forces at the local scale can be divided into 12 types with developing leading industries, increasing farmers’ income and improving agricultural production conditions as the main types; at the household scale, the nationalpolicy meeting farmers’ demands and the optimization of individual interests are all driving forces.展开更多
A socio-economic data set on China＇s historical flood losses for the period 1984--2012 was compiled to analyze the exposed population, economy, and crop area as well as the vulnerabilities of the population and econo...A socio-economic data set on China＇s historical flood losses for the period 1984--2012 was compiled to analyze the exposed population, economy, and crop area as well as the vulnerabilities of the population and economy to floods. The results revealed that the exposed population was approximately 126 persons km-2 per year when taking China as a whole; in terms of the economy, potential losses due to floods were estimated to be approximately 1.49 million C/W4 km 2 and the crop area exposed to floods covered 153 million hm2 per year. China＇s total exposure to floods significantly increased over the analysis period. The areas that showed the higher exposure were mainly located along the east coast. The population＇s vulnerability to floods showed a significantly increasing trend, however, the economic vulnerability showed a decreasing trend. The populations and economies that were most vulnerable to floods were in Hunan, Anhui, Chongqing, Jiangxi, and Hubei provinces. The municipalities of Shanghai, Beijing, and Tianjin showed the lowest vulnerabilities to floods.展开更多
Tree-ring chronologies were developed for Sabina saltuaria and Abies faxoniana in mixed forests in the Qionglai Mountains of the eastern Tibetan Plateau.Climate-growth relationship analysis indicated that the two co-e...Tree-ring chronologies were developed for Sabina saltuaria and Abies faxoniana in mixed forests in the Qionglai Mountains of the eastern Tibetan Plateau.Climate-growth relationship analysis indicated that the two co-exist-ing species reponded similarly to climate factors,although S.saltuaria was more sensitive than A.faxoniana.The strong-est correlation was between S.saltuaria chronology and regional mean temperatures from June to November.Based on this relationship,a regional mean temperature from June to November for the period 1605-2016 was constructed.Reconstruction explained 37.3%of the temperature variance during th period 1961-2016.Six major warm periods and five major cold periods were identified.Spectral analysis detected significant interannual and multi-decadal cycles.Reconstruction also revealed the influence of the Atlantic Multi-decadal Oscillation,confirming its importance on climate change on the eastern Tibetan Plateau.展开更多
This paper first introduces the background and basic concept of digital twin city,then analyzes the relationship between digital twin city and smart city.Next,it introduces the primary supporting technologies for the ...This paper first introduces the background and basic concept of digital twin city,then analyzes the relationship between digital twin city and smart city.Next,it introduces the primary supporting technologies for the construction of a digital twin city,and finally summarizes the current application status and development trends regarding digital twin city.The authors argue that digital twin technology will face challenges in regards to data,basic knowledge base,system integration,and talent issues if it is to be more widely applied in the construction of the smart city.Additionally,the authors propose institutional and technical suggestions for solving these problems at the macro and micro levels.展开更多
The long-term dynamic evolution and underlying mechanisms of coastal landscape pattern stability,driven by strong anthropogenic interference and consequently climate change,are topics of major interest in national and...The long-term dynamic evolution and underlying mechanisms of coastal landscape pattern stability,driven by strong anthropogenic interference and consequently climate change,are topics of major interest in national and international scientific research.Guangdong Province,located in southeastern China,has been undergoing rapid urbanization over several decades.In this study,we quantitatively determined the scale threshold characteristics of coastal landscape pattern stability in Guangdong Province,from the dual perspective of spatial heterogeneity and spatial autocorrelation.An analysis of the spatiotemporal evolution of the coastal landscape was conducted after the optical scale was determined.Then,we applied the geodetector statistical method to quantitatively explore the mechanisms underlying coastal landscape pattern stability.Based on the inflection point of landscape metrics and the maximum value of the MoranⅠindex,the optimal scale for analyzing coastal landscape pattern stability in Guangdong Province was 240 m×240 m.Within the past several decades,coastal landscape pattern stability increased slightly and then decreased,with a turning point around 2005.The most significant variations in coastal landscape pattern stability were observed in the transition zone of rural-urban expansion.A q-statistics analysis showed that the explanatory power of paired factors was greater than that of a single driving factor;the paired factors with the greatest impact on coastal landscape pattern stability in Guangdong Province were the change in gross industrial output and change in average annual precipitation from 2010 to 2015,based on a q value of 0.604.These results will contribute to future efforts to achieve sustainable coastal development and provide a scientific basis and technical support for the rational planning and utilization of resources in large estuarine areas,including marine disaster prevention and seawall ecological restoration.展开更多
Patterns of taxonomic and phylogenetic beta diversity and their relationships with environmental correlates can help reveal the origin and evolutionary history of regional biota.The Qinghai-Tibet Plateau(QTP)harbors a...Patterns of taxonomic and phylogenetic beta diversity and their relationships with environmental correlates can help reveal the origin and evolutionary history of regional biota.The Qinghai-Tibet Plateau(QTP)harbors an exceptionally diverse flora,however,a phylogenetic perspective has rarely been used to investigate its beta diversity and floristic regions.In this study,we used a phylogenetic approach to identify patterns of beta diversity and quantitatively delimit floristic regions on the Qinghai-Tibet Plateau.We also examined the relationships between multifaceted beta diversity,geographical distance,and climatic difference,and evaluated the relative importance of various factors(i.e.,climate,topography and history)in shaping patterns of beta diversity.Sørensen dissimilarity indices indicated that patterns of species turnover among sites dominated the QTP.We also found that patterns of both taxonomic and phylogenetic beta diversity were significantly related to geographical distance and climatic difference.The environmental factors that contributed most to these patterns of beta diversity include annual precipitation,mean annual temperature,climatic gradients and climatic instability.Hierarchical dendrograms of dissimilarity and non-metric multidimensional scaling ordination based on phylogenetic beta diversity data identified ten floristic subregions in the QTP.Our results suggest that the contemporary environment and historical climate changes have filtered species composition among sites and eventually determined beta diversity patterns of plants in the QTP.展开更多
The increasingly frequent storms pose significant threats to the sustainable development of coastal regions,particularly in densely populated and economically vibrant areas.Comprehending the dynamics and intricate mec...The increasingly frequent storms pose significant threats to the sustainable development of coastal regions,particularly in densely populated and economically vibrant areas.Comprehending the dynamics and intricate mechanisms underlying runoff generation is crucial in the context of climate change and anthropogenic interference.Based on hydro-meteorological and land-use data from 1980 to 2018,this study investigates the runoff variation and its driving factors in the Coastal Chinese Mainland(CCM).The aims of this study are to reveal the temporal and spatial trends of runoff yield,to clarify the sensitivity of runoff in coastal cities to the integrated and individual parameters of climate change and anthropogenic interference,including precipitation(P),potential evapotranspiration(E_(0)),and land cover factor(n),and to support the establishment of spatially tailored adaptation strategies.The results show that:(1)runoff has generally increased over the study period,particularly in regions such as the Yangtze River Delta,Shandong,and Guangxi,while it has decreased in western Liaoning and eastern Guangdong;(2)in the northern CCM with larger aridity index,the land cover factor plays a dominant role in runoff production,while in the wetter southern CCM,precipitation is more influential,and potential evapotranspiration mainly hinders runoff generation all over CCM;(3)urban expansion tends to negatively impact n,while the loss of grasslands and shrinkage of croplands tend to undermine the value of n.To facilitate the achievement of sustainable development goals in the CCM,it is imperative to introduce a more comprehensive and theoretical framework that encompasses the natural,technical,and social dimensions of human-water systems into traditional flood regulation and water resource management.This framework should promote interdisciplinary collaboration from an integrated perspective,to bridge the administrative and watershed boundaries,to effectively address the complex challenges posed by climate change and anthropogenic activities on runoff and water resources in coastal regions,and to enhance the realization of local sustainable development goals(UN SDGs).展开更多
The agricultural water footprint(AWF)is intricately linked to water-related Sustainable Development Goals(SDGs).This study developed a multi-dimensional indicator framework integrating AWF with social,economic,and eco...The agricultural water footprint(AWF)is intricately linked to water-related Sustainable Development Goals(SDGs).This study developed a multi-dimensional indicator framework integrating AWF with social,economic,and ecological metrics to elucidate the spatiotemporal evolution of agricultural water sustainability in Guangdong Province,China,from 2010 to 2020.By disaggregating AWF into green(soil moisture),blue(surface/groundwater),and grey(pollution-related)components,we identified the dominate drivers of sustainability transitions and proposed context-specific policy interventions.Key findings include:1)a 6.98%reduction in total AWF(from 19.35 to 18.00 km^(3))was detected,accompanied by a 14.46%improvement in the agricultural water sustainability level.2)Green water dominated(78.28%of total footprint)the AWF,while blue(19.29%)and grey water(2.43%)contributed less and exhibited lowered degree of spatial variability;3)Within the crop system,rice(Oryza sativa)accounted for nearly 60%of the AWF,and veget-ables(Vegetabilia)shared around 20%,while the rest three crops(peanut(Arachis hypogaea),banana(Musa acuminata)and oranges(Citrus sinensis))contributed another 20%.4)Western Guangdong consumed higher AWF per area,reaching 1.59 times the provincial average due to the climate and cropping system,whereas eastern regions consumed disproportionate blue water,around 1.76 times the provincial average for irrigated crop production.Optimizing AWF governance strengthens food security by enhancing blue water utiliz-ation efficiency in rice production is recommended,especially in eastern Guangdong.The formulation of rice-specific AWF bench-marks facilitates data-driven water resource policies,while strategic greywater management interventions would effectively reduce en-vironmental burdens.Context-specific strategies,such as incorporating organic fertilizer promotion,integrating constructed wetlands,rainwater capture infrastructure,and market-based regulatory tools would synergistically improve crop productivity,diminish pollutant loads,and bolster agricultural water sustainability.展开更多
Vegetation annual gross primary production(AGPP),the total yearly carbon assimilation via photosynthesis,serves as a key indicator of ecosystem carbon uptake.While AGPP variations are jointly influenced by both vegeta...Vegetation annual gross primary production(AGPP),the total yearly carbon assimilation via photosynthesis,serves as a key indicator of ecosystem carbon uptake.While AGPP variations are jointly influenced by both vegetation phenology and physiology,the effectiveness of satellite-derived indicators in capturing these variations has not been fully evaluated.This study develops and evaluates the satellite-derived phenology and physiology indicators for modeling AGPP variability.We assessed the performance of satellite-derived metrics,including solar-induced chlorophyll fluorescence(SIF),leaf area index(LAI),and enhanced vegetation index(EVI),in capturing AGPP variations.Among these,SIF-based indicators exhibited the highest accuracy(Pearson's r=0.79;root mean square error=414.7 gC·m^(-2)·year^(-1)),outperforming LAI-and EVI-based indicators.To further investigate the mechanisms driving AGPP variability,we used a structural equation model based on in situ observations to quantify the direct and indirect effects of climate on AGPP through phenology and physiology.Our results reveal that vegetation physiology,particularly the seasonal maximum gross primary production,plays a more dominant role in regulating AGPP than phenology.Furthermore,we found that globally,SIF-derived phenology indicators tend to be lower than those from LAI and EVI,whereas SIF-derived physiology indicators are elevated in tropical regions and the Southern Hemisphere.These findings highlight the potential of satellite-derived indicators in advancing AGPP modeling and emphasize the predominant role of vegetation physiology in regulating ecosystem carbon uptake.This study contributes to a refined understanding of global carbon cycle dynamics and provides insights for improving large-scale carbon assessments in the context of climate change.展开更多
Rapid determination of soil organic matter(SOM) using regression models based on soil reflectance spectral data serves an important function in precision agriculture. "Deviation of arch"(DOA)-based regressio...Rapid determination of soil organic matter(SOM) using regression models based on soil reflectance spectral data serves an important function in precision agriculture. "Deviation of arch"(DOA)-based regression and partial least squares regression(PLSR)are two modeling approaches to predict SOM.However,few studies have explored the accuracy of the DOA-based regression and PLSR models.Therefore,the DOA-based regression and PLSR were applied to the visible near-infrared(VNIR) spectra to estimate SOM content in the case of various dataset divisions.A two-fold cross-validation scheme was adopted and repeated 10 000 times for rigorous evaluation of the DOA-based models in comparison with the widely used PLSR model.Soil samples were collected for SOM analysis in the coastal area of northern Jiangsu Province,China.The results indicated that both modelling methods provided reasonable estimation of SOM,with PLSR outperforming DOA-based regression in general.However,the performance of PLSR for the validation dataset decreased more noticeably.Among the four DOA-based regression models,a linear model provided the best estimation of SOM and a cutoff of SOM content(19.76 g kg^(-1)),and the performance for calibration and validation datasets was consistent.As the SOM content exceeded 19.76 g kg^(-1),SOM became more effective in masking the spectral features of other soil properties to a certain extent.This work confirmed that reflectance spectroscopy combined with PLSR could serve as a non-destructive and cost-efficient way for rapid determination of SOM when hyperspectral data were available.The DOA-based model,which requires only 3 bands in the visible spectra,also provided SOM estimation with acceptable accuracy.展开更多
Model simulation and in situ observations are often used to research water and carbon cycles in terrestrial ecosystems, but each of these methods has its own advantages and limitations. Combining these two methods cou...Model simulation and in situ observations are often used to research water and carbon cycles in terrestrial ecosystems, but each of these methods has its own advantages and limitations. Combining these two methods could improve the accuracy of quantifying the dynamics of the water and carbon fluxes of an ecosystem. Data assimilation is an effective means of integrating modeling with in situ observation. In this study, the ensemble Kalman filter(En KF) and the unscented Kalman filter(UKF) algorithms were used to assimilate remotely sensed leaf area index(LAI) data with the Biome-BGC model to simulate water and carbon fluxes at the Harvard Forest Environmental Monitoring Site(EMS) and the Dinghushan site. After MODIS LAI data from 2000–2004 were assimilated into the improved Biome-BGC model using the En KF algorithm at the Harvard Forest site, the R2 between the simulated and observed results for NEE and evapotranspiration increased by 7.8% and 4.7%, respectively. In addition, the sum of the absolute error(SAE) and the root mean square error(RMSE) of NEE decreased by an average of 21.9% and 26.3%, and the SAE and RMSE of evapotranspiration decreased by 24.5% and 25.5%, respectively. MODIS LAI data of 2003 were assimilated into the Biome-BGC model for the Dinghushan site, and the R2 values between the simulated and observed results for NEE and evapotranspiration were increased by 6.7% and 17.3%, respectively. In addition, the SAE values of NEE and ET were decreased by 11.3% and 30.7%, respectively, and the RMSE values of NEE and ET decreased by 10.1% and 30.9%, respectively. These results demonstrate that the accuracy of carbon and water flux simulations can be effectively improved when remotely sensed LAI data are properly integrated with ecosystem models through a data assimilation approach.展开更多
Soil organic carbon(SOC) is a major component of the global carbon cycle and has a potentially large impact on the greenhouse effect. Paddy soils are important agricultural soils worldwide, especially in Asia. Thus, a...Soil organic carbon(SOC) is a major component of the global carbon cycle and has a potentially large impact on the greenhouse effect. Paddy soils are important agricultural soils worldwide, especially in Asia. Thus, a better understanding of the relationship between SOC of paddy soils and climate variables is crucial to a robust understanding of the potential effect of climate change on the global carbon cycle. A soil profile data set(n = 1490) from the Second National Soil Survey of China conducted from 1979 to 1994 was used to explore the relationships of SOC density with mean annual temperature(MAT) and mean annual precipitation(MAP) in six soil regions and eight paddy soil subgroups. Results showed that SOC density of paddy soils was negatively correlated with MAT and positively correlated with MAP(P < 0.01). The relationships of SOC density with MAT and MAP were weak and varied among the six soil regions and eight paddy soil subgroups. A preliminary assessment of the response of SOC in Chinese paddy soils to climate indicated that climate could lead to a 13% SOC loss from paddy soils. Compared to other soil regions, paddy soils in Northern China will potentially more sensitive to climate change over the next several decades. Paddy soils in Middle and Lower Yangtze River Basin could be a potential carbon sink. Reducing the climate impact on paddy soil SOC will mitigate the positive feedback loop between SOC release and global climate change.展开更多
基金National Natural Science Foundation of China(Nos.42371406,42071441,42222106,61976234).
文摘With the increasing number of remote sensing satellites,the diversification of observation modals,and the continuous advancement of artificial intelligence algorithms,historically opportunities have been brought to the applications of earth observation and information retrieval,including climate change monitoring,natural resource investigation,ecological environment protection,and territorial space planning.Over the past decade,artificial intelligence technology represented by deep learning has made significant contributions to the field of Earth observation.Therefore,this review will focus on the bottlenecks and development process of using deep learning methods for land use/land cover mapping of the Earth’s surface.Firstly,it introduces the basic framework of semantic segmentation network models for land use/land cover mapping.Then,we summarize the development of semantic segmentation models in geographical field,focusing on spatial and semantic feature extraction,context relationship perception,multi-scale effects modelling,and the transferability of models under geographical differences.Then,the application of semantic segmentation models in agricultural management,building boundary extraction,single tree segmentation and inter-species classification are reviewed.Finally,we discuss the future development prospects of deep learning technology in the context of remote sensing big data.
基金Under the auspices of Natural Science Foundation of Guangdong Province(No.2020A1515011065)Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2019)+1 种基金the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0301)the NSFC(National Natural Science Foundation of China)-Guangdong Joint Fund Key Project(No.U1901219)。
文摘Climate change and human interference play significant roles on dynamic of water body abundance,and drive related hydrological,biochemical and social/economic processes.Documenting and monitoring surface water area with high resolution multi-temporal satellite imagery provide new perspective to evaluate the dynamics of surface water area,especially in continental and global scale.In this study,based on the Landsat images from 1980 s to 2015,we surveyed the spatial and temporal variation of surface water area,including rivers,lakes and reservoirs,in 10-yr temporal slice across China.Furthermore,the driving forces of the variation has been identified to reveal the interaction of water bodies and the changing environment.The results show that,the water surface area expanded over all three decades with strong spatial and temporal difference,despite the drier and warmer climate background;although lakes comprise the largest portion of the surface water area,the highest contributor of surface water expansion was new constructed reservoir located in the densely populated region;climatic parameters alteration,like precipitation and temperature,resulted in the water surface expansion in the northwestern basin by growing water input linked with rain and glacier melting;in the rest part of China,rise of water surface area was predominately attributed to human relocation of water resource,which yielded more new water storage area than the disappeared water body caused by less precipitation and stronger evapotranspiration.The conclusions highlight the integrative water resource management,especially in water conservation and restoration.
基金Under the auspices of the National Natural Science Foundation of China(No.42271311)Open Project of State Key Laboratory of Estuarine and Coastal Sciences(No.SKLEC-KF202204)Discipline Co-construction Project on 2024 Guangdong Philosophy and Social Science Foundation(No.GD24XGL026)。
文摘Water resources play a fundamental role in maintaining ecosystem well-being and supporting socio-economic progress.Nevertheless,the water sustainability confronts unprecedented challenges exacerbated by climate change and human interventions.This research establishes a comprehensive evaluation framework aligned with the United Nations'Sustainability Development Goals(SDGs)to assess water sustainability across 30 Chinese provinces,municipalities,and autonomous regions(excluding Xizang,Hong Kong,Macao and Taiwan).By integrating natural,economic,and social factors,this research elucidated the spatiotemporal evolution patterns of water sustainability from 2010 to 2020,and projected future trajectories under diverse socio-economic pathways(SSPs)for 2030 and 2050.The main findings include:1)China's water sustainability demonstrated gradual improvement during 2010–2020,yet baseline levels remain suboptimal for achieving SDG targets in 2030.Projections suggest significant enhancements by 2050,particularly under the SSP1-2.6 sustainability-oriented scenario.2)Persistent regional disparities are evident,with acute sustainability deficits observed in densely populated,intensively cultivated northern and the arid northwestern territories.These disparities are projected to attenuate by 2050.3)Natural ecological processes emerge as the dominant contributor to water sustainability,with projected growth potential.Economic processes constitute a secondary driver,while social dimensions exhibit more limited influence,both displaying heterogeneous developmental trajectories.4)SDG 6.4(Water Use Efficiency)demonstrates the highest implementation efficiency,whereas SDG 6.3(Water Quality)and SDG 15.1(Terrestrial Ecosystem Conservation)require urgent policy interventions.This study demonstrates the applicability of the proposed SDGs-aligned framework in diagnosing China's water sustainability challenges,providing actionable insights for regional policy prioritization.The interdisciplinary methodology bridges scientific analysis and governance strategies,enabling robust decision-making under complex future uncertainties.
基金National Natural Science Foundation of China,No.U21A2022,No.U1901219,No.42071393,No.42101369。
文摘Ecosystem services in urban agglomerations are the environmental conditions under which human survival and development are sustained.Quantitative assessment of ecosystem services and complex interactions can contribute positively to the achievement of the Sustainable Development Goals(SDGs)for urban agglomerations.However,studies on the future contribution of multi-scenario ecosystem services to the SDGS are lacking.We pronovel integrated modeling framework that integrates the CLUES,InVEST,SOM,and GWR approaches to address the complex relationship between ecosystem services over a long“past-present-future”time series.We construct a novel ecosystem service bundle-based approach for measuring urban agglomerations progress towards achieving ecologically relevant sustainable development goals at multiple scales.In the future scenario,the water yield(WY),habitat quality(HQ),and soil conservation(SC)show similar spatial patterns,with comparable spatial grids,while carbon stock(CS)remains predominantly unchanged and the ecological protection scenario(EPS)improves more significantly.The high-synergy regions are mainly distributed in bundle 4,and most of the trade-off regions appear in bundles 1 and 2.Over the last 30 years,all but the water-related SDGs are declining in bundle 1 of the two urban agglomerations,which are 15%higher in the Guangxi Beibu Gulf(GBG)than in the Guangdong-Hong Kong-Macao Greater Bay Area(GBA).From 2020 to 2035,the three scenarios demonstrate that the optimization of the SDGs progresses most effectively under the future ecological protection scenario(EPS).In particular,bundles 3 and 4 are significantly improved.This critical new knowledge can be used in sustainable ecosystem management and decision-making in urban agglomerations.
基金Under the auspices of National Natural Science Foundation of China(No.U21A2022,U1901219,42101369)National Key Research and Development Program of China(No.2023YFF0807204)。
文摘Wetlands offer important ecological functions and values.Wetland functional zoning provides a reference and basis for sustainable fulfilment and management.In this study,two coastal urban agglomerations in South China were taken as study areas,namely,the Guangxi Beibu Gulf(GBG)and Guangdong-Hong Kong-Macao Greater Bay Area(GBA).Based on multisource information data,a wetland functional zoning system was constructed with the four levels of zoning concept,zoning principle,zoning basis,and zoning scheme.The functional zoning and dynamic analysis of wetlands from 1990 to 2020 were carried out from multiple perspectives of wetland ecological functions,wetland management and conservation functions.The results showed that:1)in terms of wetland ecological functions,the two coastal urban agglomerations were dominated by hydrological regulation and purification of environmental functional areas.The coastal region was largely characterized by the main functional areas of climate regulation and biodiversity maintenance.2)Regarding wetland management and conservation functions,two coastal urban agglomerations exhibited similar trends in terms of the sizes of their conservation and buffer zones from 1990 to 2020.Prevention and control zones were mainly located in core cities in a concentrated manner.Conservation zones largely comprised mountainous woodlands and important wetlands.3)The two coastal urban agglomerations could be divided into 21 wetland functional zones.The central river area has remained the main prevention and control zone for many years.Regarding conservation zones,ecological protection and restoration should be the main focus.Regarding buffer zones,the construction of wetlands and surrounding complex systems should be strengthened or enhanced.Regarding prevention and control zones,activities that do not affect wetland functions should be allowed,provided that they comply with existing laws and regulations.This study could provide technical support and practical application guidance for wetland regulation and management.
基金supported by the National Key R&D Program(No.2021YFE0117300)the National Natural Science Foundation of China(No.42375090)+6 种基金Shenzhen Key Laboratory of Precision Measurement and Early Warning Technology for Urban Environmental Health Risks(No.ZDSYS20220606100604008)Guangdong Basic and Applied Basic Research Foundation(No.2021A1515110713)Guangdong University Research Project Science Team(No.2021KCXTD004)the Major Talent Project of Guangdong Province(No.2021QN020924)Shandong Provincial Natural Science Foundation,China(No.ZR2020QD012)Shenzhen Science and Technology Program(Nos.KQTD20210811090048025,JCYJ20210324104604012 and JCYJ20220530115404009)supported by the Center for Computational Science and Engineering at Southern University of Science and Technology.
文摘Ozone production sensitivity is widely used to reveal the chemical dominant precursors of urban ozone rise.Here,we diagnose the impact of the decline in global human production activities level caused by the COVID-19 on ozone sensitivity through the ratio of formaldehyde(HCHO)and NO_(2)(FNR=HCHO/NO_(2))observations from the TROPOspheric Monitoring Instrument.We use a relative uncertainty threshold to clean the satellite FNR,and our satellite FNR present a good correlation(R=0.6248)with U.S.Environmental Protection Agency observations.We found that the outbreak of the COVID-19 did not change the pattern of global ozone sensitivity,while the global regimes was transforming or strengthening to VOC-limited regimes due to the significant decline of human production activities levels.During the COVID-19,ozone sensitivity in Eastern China and East Africa continued to shift to VOC-limited regimes,while India,Western Europe and North America first moved to NOx-limited regimes,and then changed to VOC-limited regimes with the resumption of production and the increase in travel.The clustering results tell that urban ozone sensitivity tends to shift towards NOx-limited regimes as economic growing.The ozone formation in cities with lower FNR and per capita gross domestic product(GDP)are more sensitive to changes in VOCs,while cities with higher FNR and per capita GDP are more sensitive to variations in NOx.Cities with intermediate FNR and GDP are good evidence of the existence of transitional regimes.Our study identifies the driving role of urban economics in orienting the evolution of ozone sensitivity regimes.
基金funded by the National Natural Science Foundation of China (Grant no. 40971221)the National High Technology Research and Development Program of China (863 Program) (Grant no. 2012AA12A304)
文摘Net primary productivity （NPP） and evapotranspiration （ET） are two key variables in the carbon and water cycles of terrestrial ecosystems. In this study, to test a newly developed NPP algorithm designed for H J-1 A/B data and to evaluate the usage of HJ-1 A/B data in the quantitative assessment of environments, NPP and ET in Jinggangshan city, Jiangxi province, are calculated using H J-1 A/B data. The results illustrate the following： （1） The NPP and ET in Jinggangshan city in 2olo both show obvious seasonal variation, with the highest values in summer and the lowest values in winter, and relatively higher values were observed in autumn than in spring. （2） The spatial pattern indicates that the annual NPP is high in the southern area in Jinggangshan city and low in the northern area. Additionally, high NPP is distributed in forests located in areas with high elevation, and low NPP is found in croplands at low elevations. ET has no significant north-south difference, with high values in the southeast and northwest and low values in the southwest, and high ET is distributed in forests at low elevations in contrast to low ET in forests in high-elevation areas and in cropland and shrub grassland in low-elevation areas. （3） Compared to the MODIS product, the range of H J-1 NPP is larger, and the spatial pattern is more coincident with the topography. The range of H J-1 ET is smaller than that of the MODIS product, and ET is underestimated to some extent but can reflect the effect of topography. This study suggests that the algorithm can be used to estimate NPP and ET in a subtropical monsoon climate if remotely sensed images with high spatial resolution are available.
基金Under the auspices of Global Environment Facility (TA4629)
文摘As one of the few ecological wetlands in North China,Baiyangdian bears multiple important ecological functions,including ①adjusting the ecological balance of North China;②safeguarding the downstream areas,especially Tianjin City,the Beijing-Shanghai Railway and Huabei Oil Field;③serving as the reservoir for the North-to-South Water Diversion Project and the emergent use of water for Beijing;④conserving biodiversity.Wetland ecotourism is a scientific and wise use pattern for wetland resources,through which,a source of financing is provided for wetland conservation,economic alternatives are generated for local people to reduce overexploitation on wetland resources and the public awareness of environmental protection is enhanced.Since wetland ecotourism can benefit the co-existence between human and nature and promote social equity between people,it enjoys broad promise for popularization and implementation.The proactive cooperation and sound interaction between main stakeholders,and the wide participation of the community residents,will guarantee the sustainable development of wetland ecotourism.Based on the analysis of current status of participation and interactive relationships of the main stakeholders in Baiyangdian tourism,this article made an attempt to apply the theory of participatory development to the ecotourism initiatives of Baiyangdian wetland,discussed and brought forward the countermeasures to improve community participation in wetland ecotourism under the guidance of this theory.
文摘Increasing populations are causing an increase in food demands, and the area of cultivated land expands every year. Inappropriate land transition from ecology to production results in the constant decline of the ecological security level and influences the regional sustainable development. Adjusting unreasonable land use mode and reconstructing natural land cover are important ways to maintain and improve the ecological environment. Also reclaiming farmland as areas for forests and grasslands (FRFG) is another way. Successful implementation of FRFG in China is the result of comprehensive effect of the multi-scales driving forces. This paper analyses the driving forces of FRFG in China on a national (country) –regional (province) – local (county) – household (farmer) level scale, and the results are: driving forces at the national scale include ecological and food security and the western development of China; at the regional scale, ecological and economic benefits become the main factors to influence the dimension of FRFG under the same policy. The driving forces can be divided into 6 types: industrial structure adjustment, water source protection, flood prevention, the Three-Gorge Project protection, reduction of the amount of sediment flowing into the Yellow River and wind erosion desertification prevention. The driving forces at the local scale can be divided into 12 types with developing leading industries, increasing farmers’ income and improving agricultural production conditions as the main types; at the household scale, the nationalpolicy meeting farmers’ demands and the optimization of individual interests are all driving forces.
基金supported by the National Basic Research Program of China(No.2012CB955903)
文摘A socio-economic data set on China＇s historical flood losses for the period 1984--2012 was compiled to analyze the exposed population, economy, and crop area as well as the vulnerabilities of the population and economy to floods. The results revealed that the exposed population was approximately 126 persons km-2 per year when taking China as a whole; in terms of the economy, potential losses due to floods were estimated to be approximately 1.49 million C/W4 km 2 and the crop area exposed to floods covered 153 million hm2 per year. China＇s total exposure to floods significantly increased over the analysis period. The areas that showed the higher exposure were mainly located along the east coast. The population＇s vulnerability to floods showed a significantly increasing trend, however, the economic vulnerability showed a decreasing trend. The populations and economies that were most vulnerable to floods were in Hunan, Anhui, Chongqing, Jiangxi, and Hubei provinces. The municipalities of Shanghai, Beijing, and Tianjin showed the lowest vulnerabilities to floods.
基金supported by the National Key Research and Development Program of China(No.2018YFA0605601)Hong Kong Research Grants Council(No.106220169)+1 种基金the National Natural Science Foundation of China(Nos.41671042,42077417,42105155,and 42201083)the National Geographic Society(No.EC-95776R-22).
文摘Tree-ring chronologies were developed for Sabina saltuaria and Abies faxoniana in mixed forests in the Qionglai Mountains of the eastern Tibetan Plateau.Climate-growth relationship analysis indicated that the two co-exist-ing species reponded similarly to climate factors,although S.saltuaria was more sensitive than A.faxoniana.The strong-est correlation was between S.saltuaria chronology and regional mean temperatures from June to November.Based on this relationship,a regional mean temperature from June to November for the period 1605-2016 was constructed.Reconstruction explained 37.3%of the temperature variance during th period 1961-2016.Six major warm periods and five major cold periods were identified.Spectral analysis detected significant interannual and multi-decadal cycles.Reconstruction also revealed the influence of the Atlantic Multi-decadal Oscillation,confirming its importance on climate change on the eastern Tibetan Plateau.
基金National Natural Science Foundation of China(42071441)National Key R&D Program of China(2018YFB2100702)Spatio-temporal Information Cloud Platform Project of Smart Guangzhou(GZIT2016-A5-147)。
文摘This paper first introduces the background and basic concept of digital twin city,then analyzes the relationship between digital twin city and smart city.Next,it introduces the primary supporting technologies for the construction of a digital twin city,and finally summarizes the current application status and development trends regarding digital twin city.The authors argue that digital twin technology will face challenges in regards to data,basic knowledge base,system integration,and talent issues if it is to be more widely applied in the construction of the smart city.Additionally,the authors propose institutional and technical suggestions for solving these problems at the macro and micro levels.
基金The National Natural Science Foundation of China under contract Nos 42201104 and 42071123the China Postdoctoral Research Foundation under contract No.2023M730758.
文摘The long-term dynamic evolution and underlying mechanisms of coastal landscape pattern stability,driven by strong anthropogenic interference and consequently climate change,are topics of major interest in national and international scientific research.Guangdong Province,located in southeastern China,has been undergoing rapid urbanization over several decades.In this study,we quantitatively determined the scale threshold characteristics of coastal landscape pattern stability in Guangdong Province,from the dual perspective of spatial heterogeneity and spatial autocorrelation.An analysis of the spatiotemporal evolution of the coastal landscape was conducted after the optical scale was determined.Then,we applied the geodetector statistical method to quantitatively explore the mechanisms underlying coastal landscape pattern stability.Based on the inflection point of landscape metrics and the maximum value of the MoranⅠindex,the optimal scale for analyzing coastal landscape pattern stability in Guangdong Province was 240 m×240 m.Within the past several decades,coastal landscape pattern stability increased slightly and then decreased,with a turning point around 2005.The most significant variations in coastal landscape pattern stability were observed in the transition zone of rural-urban expansion.A q-statistics analysis showed that the explanatory power of paired factors was greater than that of a single driving factor;the paired factors with the greatest impact on coastal landscape pattern stability in Guangdong Province were the change in gross industrial output and change in average annual precipitation from 2010 to 2015,based on a q value of 0.604.These results will contribute to future efforts to achieve sustainable coastal development and provide a scientific basis and technical support for the rational planning and utilization of resources in large estuarine areas,including marine disaster prevention and seawall ecological restoration.
基金This study was funded by the National Natural Science Foundation of China(grant no.31901212)Talent Start-up Foundation of Guangzhou University(grant no.RP2020079).
文摘Patterns of taxonomic and phylogenetic beta diversity and their relationships with environmental correlates can help reveal the origin and evolutionary history of regional biota.The Qinghai-Tibet Plateau(QTP)harbors an exceptionally diverse flora,however,a phylogenetic perspective has rarely been used to investigate its beta diversity and floristic regions.In this study,we used a phylogenetic approach to identify patterns of beta diversity and quantitatively delimit floristic regions on the Qinghai-Tibet Plateau.We also examined the relationships between multifaceted beta diversity,geographical distance,and climatic difference,and evaluated the relative importance of various factors(i.e.,climate,topography and history)in shaping patterns of beta diversity.Sørensen dissimilarity indices indicated that patterns of species turnover among sites dominated the QTP.We also found that patterns of both taxonomic and phylogenetic beta diversity were significantly related to geographical distance and climatic difference.The environmental factors that contributed most to these patterns of beta diversity include annual precipitation,mean annual temperature,climatic gradients and climatic instability.Hierarchical dendrograms of dissimilarity and non-metric multidimensional scaling ordination based on phylogenetic beta diversity data identified ten floristic subregions in the QTP.Our results suggest that the contemporary environment and historical climate changes have filtered species composition among sites and eventually determined beta diversity patterns of plants in the QTP.
基金supported by the National Natural Science Foundation of China(Grant No.42271311)Open Project of State Key Laboratory of Estuarine and Coastal Sciences(Grant No.SKLEC-KF202204)+1 种基金Guangzhou city-Guangzhou university joint funding program(Grant No.202201020215)Key Project of the National Natural Science Foundation of China-Guangdong Joint Fund(Grant No.U1901219).
文摘The increasingly frequent storms pose significant threats to the sustainable development of coastal regions,particularly in densely populated and economically vibrant areas.Comprehending the dynamics and intricate mechanisms underlying runoff generation is crucial in the context of climate change and anthropogenic interference.Based on hydro-meteorological and land-use data from 1980 to 2018,this study investigates the runoff variation and its driving factors in the Coastal Chinese Mainland(CCM).The aims of this study are to reveal the temporal and spatial trends of runoff yield,to clarify the sensitivity of runoff in coastal cities to the integrated and individual parameters of climate change and anthropogenic interference,including precipitation(P),potential evapotranspiration(E_(0)),and land cover factor(n),and to support the establishment of spatially tailored adaptation strategies.The results show that:(1)runoff has generally increased over the study period,particularly in regions such as the Yangtze River Delta,Shandong,and Guangxi,while it has decreased in western Liaoning and eastern Guangdong;(2)in the northern CCM with larger aridity index,the land cover factor plays a dominant role in runoff production,while in the wetter southern CCM,precipitation is more influential,and potential evapotranspiration mainly hinders runoff generation all over CCM;(3)urban expansion tends to negatively impact n,while the loss of grasslands and shrinkage of croplands tend to undermine the value of n.To facilitate the achievement of sustainable development goals in the CCM,it is imperative to introduce a more comprehensive and theoretical framework that encompasses the natural,technical,and social dimensions of human-water systems into traditional flood regulation and water resource management.This framework should promote interdisciplinary collaboration from an integrated perspective,to bridge the administrative and watershed boundaries,to effectively address the complex challenges posed by climate change and anthropogenic activities on runoff and water resources in coastal regions,and to enhance the realization of local sustainable development goals(UN SDGs).
基金Under the auspices of the National Natural Science Foundation of China(No.42271311)Open Project of State Key Laboratory of Estuarine and Coastal Sciences(No.SKLEC-KF202204)。
文摘The agricultural water footprint(AWF)is intricately linked to water-related Sustainable Development Goals(SDGs).This study developed a multi-dimensional indicator framework integrating AWF with social,economic,and ecological metrics to elucidate the spatiotemporal evolution of agricultural water sustainability in Guangdong Province,China,from 2010 to 2020.By disaggregating AWF into green(soil moisture),blue(surface/groundwater),and grey(pollution-related)components,we identified the dominate drivers of sustainability transitions and proposed context-specific policy interventions.Key findings include:1)a 6.98%reduction in total AWF(from 19.35 to 18.00 km^(3))was detected,accompanied by a 14.46%improvement in the agricultural water sustainability level.2)Green water dominated(78.28%of total footprint)the AWF,while blue(19.29%)and grey water(2.43%)contributed less and exhibited lowered degree of spatial variability;3)Within the crop system,rice(Oryza sativa)accounted for nearly 60%of the AWF,and veget-ables(Vegetabilia)shared around 20%,while the rest three crops(peanut(Arachis hypogaea),banana(Musa acuminata)and oranges(Citrus sinensis))contributed another 20%.4)Western Guangdong consumed higher AWF per area,reaching 1.59 times the provincial average due to the climate and cropping system,whereas eastern regions consumed disproportionate blue water,around 1.76 times the provincial average for irrigated crop production.Optimizing AWF governance strengthens food security by enhancing blue water utiliz-ation efficiency in rice production is recommended,especially in eastern Guangdong.The formulation of rice-specific AWF bench-marks facilitates data-driven water resource policies,while strategic greywater management interventions would effectively reduce en-vironmental burdens.Context-specific strategies,such as incorporating organic fertilizer promotion,integrating constructed wetlands,rainwater capture infrastructure,and market-based regulatory tools would synergistically improve crop productivity,diminish pollutant loads,and bolster agricultural water sustainability.
基金support from the National Natural Science Foundation of China(Nos.42450226,42371483,and 42171308)the Natural Science Foundation of Guangdong Province,China(No.2025A1515010770)the Postdoctoral Fellowship Program of CPSF(No.GZB20240880).
文摘Vegetation annual gross primary production(AGPP),the total yearly carbon assimilation via photosynthesis,serves as a key indicator of ecosystem carbon uptake.While AGPP variations are jointly influenced by both vegetation phenology and physiology,the effectiveness of satellite-derived indicators in capturing these variations has not been fully evaluated.This study develops and evaluates the satellite-derived phenology and physiology indicators for modeling AGPP variability.We assessed the performance of satellite-derived metrics,including solar-induced chlorophyll fluorescence(SIF),leaf area index(LAI),and enhanced vegetation index(EVI),in capturing AGPP variations.Among these,SIF-based indicators exhibited the highest accuracy(Pearson's r=0.79;root mean square error=414.7 gC·m^(-2)·year^(-1)),outperforming LAI-and EVI-based indicators.To further investigate the mechanisms driving AGPP variability,we used a structural equation model based on in situ observations to quantify the direct and indirect effects of climate on AGPP through phenology and physiology.Our results reveal that vegetation physiology,particularly the seasonal maximum gross primary production,plays a more dominant role in regulating AGPP than phenology.Furthermore,we found that globally,SIF-derived phenology indicators tend to be lower than those from LAI and EVI,whereas SIF-derived physiology indicators are elevated in tropical regions and the Southern Hemisphere.These findings highlight the potential of satellite-derived indicators in advancing AGPP modeling and emphasize the predominant role of vegetation physiology in regulating ecosystem carbon uptake.This study contributes to a refined understanding of global carbon cycle dynamics and provides insights for improving large-scale carbon assessments in the context of climate change.
基金supported by the National Natural Science Foundation of China (No. 41201215)
文摘Rapid determination of soil organic matter(SOM) using regression models based on soil reflectance spectral data serves an important function in precision agriculture. "Deviation of arch"(DOA)-based regression and partial least squares regression(PLSR)are two modeling approaches to predict SOM.However,few studies have explored the accuracy of the DOA-based regression and PLSR models.Therefore,the DOA-based regression and PLSR were applied to the visible near-infrared(VNIR) spectra to estimate SOM content in the case of various dataset divisions.A two-fold cross-validation scheme was adopted and repeated 10 000 times for rigorous evaluation of the DOA-based models in comparison with the widely used PLSR model.Soil samples were collected for SOM analysis in the coastal area of northern Jiangsu Province,China.The results indicated that both modelling methods provided reasonable estimation of SOM,with PLSR outperforming DOA-based regression in general.However,the performance of PLSR for the validation dataset decreased more noticeably.Among the four DOA-based regression models,a linear model provided the best estimation of SOM and a cutoff of SOM content(19.76 g kg^(-1)),and the performance for calibration and validation datasets was consistent.As the SOM content exceeded 19.76 g kg^(-1),SOM became more effective in masking the spectral features of other soil properties to a certain extent.This work confirmed that reflectance spectroscopy combined with PLSR could serve as a non-destructive and cost-efficient way for rapid determination of SOM when hyperspectral data were available.The DOA-based model,which requires only 3 bands in the visible spectra,also provided SOM estimation with acceptable accuracy.
基金supported by the National Natural Science Foundation of China(Grant Nos.41301451&41471349)the Fundamental Research Funds for the Central Universities(Grant No.QN2013074)China’s Qian-Ren Program
文摘Model simulation and in situ observations are often used to research water and carbon cycles in terrestrial ecosystems, but each of these methods has its own advantages and limitations. Combining these two methods could improve the accuracy of quantifying the dynamics of the water and carbon fluxes of an ecosystem. Data assimilation is an effective means of integrating modeling with in situ observation. In this study, the ensemble Kalman filter(En KF) and the unscented Kalman filter(UKF) algorithms were used to assimilate remotely sensed leaf area index(LAI) data with the Biome-BGC model to simulate water and carbon fluxes at the Harvard Forest Environmental Monitoring Site(EMS) and the Dinghushan site. After MODIS LAI data from 2000–2004 were assimilated into the improved Biome-BGC model using the En KF algorithm at the Harvard Forest site, the R2 between the simulated and observed results for NEE and evapotranspiration increased by 7.8% and 4.7%, respectively. In addition, the sum of the absolute error(SAE) and the root mean square error(RMSE) of NEE decreased by an average of 21.9% and 26.3%, and the SAE and RMSE of evapotranspiration decreased by 24.5% and 25.5%, respectively. MODIS LAI data of 2003 were assimilated into the Biome-BGC model for the Dinghushan site, and the R2 values between the simulated and observed results for NEE and evapotranspiration were increased by 6.7% and 17.3%, respectively. In addition, the SAE values of NEE and ET were decreased by 11.3% and 30.7%, respectively, and the RMSE values of NEE and ET decreased by 10.1% and 30.9%, respectively. These results demonstrate that the accuracy of carbon and water flux simulations can be effectively improved when remotely sensed LAI data are properly integrated with ecosystem models through a data assimilation approach.
基金Under the auspices of National Natural Science Foundation of China(No.41301242,41201213)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA05050509)
文摘Soil organic carbon(SOC) is a major component of the global carbon cycle and has a potentially large impact on the greenhouse effect. Paddy soils are important agricultural soils worldwide, especially in Asia. Thus, a better understanding of the relationship between SOC of paddy soils and climate variables is crucial to a robust understanding of the potential effect of climate change on the global carbon cycle. A soil profile data set(n = 1490) from the Second National Soil Survey of China conducted from 1979 to 1994 was used to explore the relationships of SOC density with mean annual temperature(MAT) and mean annual precipitation(MAP) in six soil regions and eight paddy soil subgroups. Results showed that SOC density of paddy soils was negatively correlated with MAT and positively correlated with MAP(P < 0.01). The relationships of SOC density with MAT and MAP were weak and varied among the six soil regions and eight paddy soil subgroups. A preliminary assessment of the response of SOC in Chinese paddy soils to climate indicated that climate could lead to a 13% SOC loss from paddy soils. Compared to other soil regions, paddy soils in Northern China will potentially more sensitive to climate change over the next several decades. Paddy soils in Middle and Lower Yangtze River Basin could be a potential carbon sink. Reducing the climate impact on paddy soil SOC will mitigate the positive feedback loop between SOC release and global climate change.
