The continuous decrease of low-slope cropland resources caused by construction land crowding poses huge threat to regional sustainable development and food security.Slope spectrum analysis of topographic and geomorphi...The continuous decrease of low-slope cropland resources caused by construction land crowding poses huge threat to regional sustainable development and food security.Slope spectrum analysis of topographic and geomorphic features is considered as a digital terrain analysis method which reflects the macro-topographic features by using micro-topographic factors.However,pieces of studies have extended the concept of slope spectrum in the field of geoscience to construction land to explore its expansion law,while research on the slope trend of cropland from that perspective remains rare.To address the gap,in virtue of spatial analysis and geographically weighted regression(GWR)model,the cropland use change in the Yangtze River Basin(YRB)from 2000 to 2020 was analyzed and the driving factors were explored from the perspective of slope spectrum.Results showed that the slope spectrum curves of cropland area-frequency in the YRB showed a first upward then a downward trend.The change curve of the slope spectrum of cropland in each province(municipality)exhibited various distribution patterns.Quantitative analysis of morphological parameters of cropland slope spectrum revealed that the further down the YRB,the stronger the flattening characteristics,the more obvious the concentration.The province experienced the greatest downhill cropland climbing(CLC)was Shannxi,while province experienced the highest uphill CLC was Zhejiang.The most common cropland use change type in the YRB was horizontal expansion type.The factors affecting average cropland climbing index(ACCI)were quite stable in different periods,while population density(POP)changed from negative to positive during the study period.This research is of practical significance for the rational utilization of cropland at the watershed scale.展开更多
Climate change threatens China’s rice production,making it crucial to assess the impact of climate change and climate year type(CYT)on rice production across regions to safeguard food security.The impact of climate c...Climate change threatens China’s rice production,making it crucial to assess the impact of climate change and climate year type(CYT)on rice production across regions to safeguard food security.The impact of climate change under nine CYTs with different combinations of temperature and precipitation on two rice cropping systems,including single rice and double rice(early and late rice)was evaluated.The results indicate that:(1)the Northeast region was expected to undergo the greatest warming of 2.03–2.48℃,and future climate conditions would be dominated by Warm-Humid,Warm-Normal,and Warm-Dry CYTs across all regions.(2)Climate change would significantly shorten anthesis days after sowing and maturity days after sowing of single rice by 6–12 days and 9–24 days,with little change observed for late rice(<1 day).Late rice yield suffered more from climate change compared to single and early rice yield,declining by 8.8%–16.13%.(3)Different CYTs exhibited varying impacts on rice yields.Yields were projected to decrease by approximately 4.765%to 18.645%in Warm-Humid,Warm-Normal,and Warm-Dry CYTs.Conversely,the Northeast region was anticipated to experience an increase in yield.(4)Relationships between rice yield and meteorological factors varied by region,variety,and CYT.Among the nine CYTs,high killing degree days,mean daily temperature,mean solar radiation and warm spell duration index were the main factors influencing changes in rice yield,explaining nearly 80%of yield change.Our results would help to develop adaptation strategies in different regions and rice cropping systems.展开更多
In recent decades,the spatio-temporal patterns of China’s croplands have been reshaped by disturbances from anthropogenic activities,with complex changes in the topographic characteristics of croplands.Slope-climbing...In recent decades,the spatio-temporal patterns of China’s croplands have been reshaped by disturbances from anthropogenic activities,with complex changes in the topographic characteristics of croplands.Slope-climbing of croplands(SCCL)is an important issue that threatens sustainable agricultural development.While providing land with prominent location advantages,SCCL weakens the water and fertilizer retention capacity for cropland,intensifies various geological disasters,and adversely affects the ecological environment and food yield of these croplands.It is crucial to determine the spatio-temporal variation features and effects of SCCL in China to formulate more accurate cropland protection policies and to maintain food security;however,the current lack of relevant studies is detrimental for capturing trends in cropland resources and sustainable cropland use.In this study,we constructed a multi-scale slope spectrum for cropland and total terrain to explore the spatial differences and trends of SCCL from a three-dimensional view.We evaluated the natural and socioeconomic effects of SCCL in China from multiple perspectives.Results indicate that the proportion of cropland with slopes below 2°,5°,and 6°in China decreased by 0.43%,0.47%,and 0.50%from 1980 to 2020,respectively.SCCL became apparent during 1980-1990 and 2010-2020,especially over the recent decade.The cropland climbing index(CCI)and upper limited slope change(ULSC)to measure the spatio-temporal pattern of SCCL were 0.99%and 1.17°,respectively,during 2010-2020.At the agricultural regional scale,the SCCL was also concentrated in 1980-1990 and 2010-2020,and it is more pronounced in the southern areas.The proportion of provinces and prefecture-level cities with high-intensity SCCL during 1980-2020 were 87.10%and 49.73%,respectively.SCCL was comparatively more pronounced and broader from 2010 to 2020.During this period,17.84%of prefecture-level cities had no SCCL,and the average CCI for all prefecture-level cities peaked at 1.62%.In this study,we also evaluated the pros and cons of SCCL and provided targeted suggestions for decision makers and farmers to refine cropland protection policy systems and further develop the sustainable use of croplands.展开更多
Cropland elevation uplift(CLEU) has recently become a new challenge for agricultural modernization,food security,and sustainable cropland use in China.Uncovering the rules of CLEU is of great theoretical and practical...Cropland elevation uplift(CLEU) has recently become a new challenge for agricultural modernization,food security,and sustainable cropland use in China.Uncovering the rules of CLEU is of great theoretical and practical significance for China’s sustainable agricultural development and rural revitalization strategy.However,existing studies lack in-depth disclosure of multi-scale CLEU evolution rules,making it difficult to support the formulation of specific cropland protection policies.We analyzed the spatio-temporal evolution and multiscale CLEU in China from 1980 to 2020 using the Lorenz curve,gravity center model,hotspot analysis,and cropland elevation spectrum.The results indicated that the center of gravity of cropland moved to the northeast from 1980 to 2000 and then shifted to the northwest.The spatial distribution of cropland became increasingly imbalanced from 1980 to 2000.The change hotspots clustered in the northwest and the northeast,whereas cold-spots were mainly in southeastern China.The average elevation of cropland increased by 17.38 m,and the elevation uplift rule in different regions differed evidently across scales.From 1980 to 2000,all provinces except Xinjiang,Inner Mongolia,Gansu,and Yunnan exhibited CLEU,with Qinghai,Tibet,Beijing,and Guangdong showing the most noticeable uplifting.The CLEU can alleviate the shortage of cropland to some extent.However,without a planning constraint,the CLEU will lead to the increase of ecological risk and food security risk.展开更多
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 environment...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 2020.Utilizing 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.展开更多
The response of agricultural productivity anomalies to drought stress plays a crucial role in the carbon cycle within terrestrial ecosystems and in ensuring food security. However, detailed analysis of how global agri...The response of agricultural productivity anomalies to drought stress plays a crucial role in the carbon cycle within terrestrial ecosystems and in ensuring food security. However, detailed analysis of how global agricultural productivity anomalies response to drought stress, particularly within irrigated and rainfed agricultural systems, remains insufficient. In this study, the impact of drought stress on agricultural productivity anomalies during the growing season(zcNDVI^(S)), across both irrigated and rainfed agriculture, were analyzed using a suite of hydro-climatic variables. Specifically, the investigation utilized the multi-scalar Standardized Precipitation Evapotranspiration Index(SPEI), the Multivariate ENSO Index(MEI), and the Madden-Julian Oscillation(MJO). Meanwhile, the relationships between hydroclimatic variables and zcNDVI^(S) were analyzed at one, two, three and four months before the ending of growing season(EOS). Results showed that(1) the percentages of significant(p<0.1) drying trends varied across the globe from 8.30% to 13.42%, 6.50% to 14.63%, 6.52% to 14.23%, and 6.47%to 14.95% at one-, two-, three-, and four-month lead times before EOS, respectively, during 2001–2020, which represented by the multiscalar SPEI. This observation highlights that most regions across the globe tend to be arid, which could significantly impact agricultural productivity;(2) the global mean correlation coefficients(rmax) for SPEI-1, SPEI-3, SPEI-6, SPEI-12(indicating SPEI at 1-, 3-, 6-, and 12-month lags), MEI, and MJO with zcNDVI^(S) ranged between 0.24–0.25, 0.27–0.28, 0.25–0.26, 0.21–0.22, –0.02–0.01 and 0.06–0.11, respectively, across both irrigated and rainfed agriculture system from 2001 to 2020.Agricultural productivity anomalies demonstrated a significant correlation with drought stress. The strongest correlations were noted for SPEI-3 and SPEI-6, suggesting a delayed response of crops to drought conditions. This indicates that agriculture ecosystem experiences prolonged disturbances due to abiotic drought stress;and(3) the percentages of regions that showed significant correlations(p<0.1) between zcNDVI^(S)and drought indices(SPEI-1, SPEI-3, SPEI-6, and SPEI-12), as well as climate indices(MEI and MJO) ranged as follows: 14.77%–20.27%, 21.51%–32.55%, 22.60%–35.68%, 21.89%–35.16%,7.93%–11.20% and 9.44%–17.94%. Quantitatively identifying how zcNDVI^(S) spatially responds to hydro-climatic variables can help us better understand the impact of drought on agricultural productivity anomalies worldwide.展开更多
In recent years,there has been a pronounced increase in the frequency of extreme weather events.To compre hensively examine the impact of extreme weather on ecosystem services within the Wuhan Urban Agglomera tion(WUA...In recent years,there has been a pronounced increase in the frequency of extreme weather events.To compre hensively examine the impact of extreme weather on ecosystem services within the Wuhan Urban Agglomera tion(WUA),this study utilized meteorological station data,the Mann-Kendall(MK)test,and the Standardized Precipitation-Evapotranspiration Index(SPEI)to quantify the variation trends in heatwaves(HW)and droughts from 1961 to 2020.Then the Integrated Valuation of Ecosystem Services and Trade-offs(InVEST)model was employed to evaluate and compare the differences in water yield and climate regulation ecosystem services un der various HW,droughts,and HW-drought combination scenarios.The results show that over the past 60 years,the temperature,duration,and frequency of HW have significantly increased in the WUA.Specifically,the high est HW temperature,total HW days,HW frequency,and average HW temperature showed changing trend of+0.17℃/decade,+1.4 day/decade,+0.19 event/decade,and+0.07℃/decade,respectively.The year 2000 was identified as a mutation year for HW,characterized by increased frequency and heightened severity thereafter.The SPEI value exhibited an insignificant upward trend,with 1980 marked as a mutation year,indicating a de creasing trend in drought occurrences after 1980.Heatwaves have a weakening effect on both water yield and climate regulation services,while drought significantly weakened water yield and had a relatively modest effect on climate regulation.During HW-drought composite period,the average monthly water yield showed a notable discrepancy of 60 mm compared to humid years.Besides,as heatwaves intensify,the area of low aggregation for ecosystem services expands,whereas the area of high aggregation decreases.This study provides a preliminary understanding of the impact of urban extreme weather on urban ecosystem services under changing climatic conditions.展开更多
Compared with physical models,WRF-Solar,as an excellent numerical forecasting model,includes abundant novel cloud physical and dynamical processes,which enablesenable the high-frequency output of radiation components ...Compared with physical models,WRF-Solar,as an excellent numerical forecasting model,includes abundant novel cloud physical and dynamical processes,which enablesenable the high-frequency output of radiation components which are urgently needed by the solar energy industry.However,the popularisation of WRF-Solar in a wide range of applications,such as the estimation of diffuse radiation,suffers from unpredictable influences of cloud and aerosol optical property parameters.This study assessed the accuracy of the improved numerical weather prediction(WRF-Solar)model in simulating global and diffuse radiation.Aerosol optical properties at 550 nm,which were provided by a moderate resolution imaging spectroradiometer,were used as input to analyse the differences in accuracies obtained by the model with/without aerosol input.The sensitivity of WRF-Solar to aerosol and cloud optical properties and solar zenith angle(SZA)was analysed.The results show the superiority of WRF-Solar to WRF-Dudhia in terms of their root mean square error(RMSE)and mean absolute error(MAE).The coefficients of determination between WRF-Solar and WRF-Dudhia revealed no statistically significant difference,with values greater than 0.9 for the parent and nested domains.In addition,the relative RMSE(RRMSE%)reached 46.60%.The experiment on WRF-Solar and WRF-Dudhia revealed a negative bias for global radiation,but WRF-Solar attained a slightly lower RMSE and higher correlation coefficient than WRF-Dudhia.The WRF-Solar-simulated results on diffuse radiation under clear sky conditions were slightly poorer,with RMSE,RRMSE,mean percentage error and MAE of 181.93 W m^(−2),170.52%,93.04%and 138 W m^(−2),respectively.Based on Himawari-8 cloud data,statistical results on cloud optical thickness(COT)for cloudy days revealed that WRF-Solar overestimated diffuse radiation at COTs greater than 20.Moreover,when the aerosol optical depth was greater than or equal to 0.8,WRF-Solar also overestimated the diffuse radiation,with a mean difference of 58.57 W m^(−2).The errors of WRF-Solar simulations in global and diffuse radiation exhibited a significant dependence on the SZA.The dispersion degree of deviation increased gradually with the decrease in the SZA.Thus,WRF-Solar serves as an improved numerical tool that can provide high temporal and high-spatial-resolution solar radiation data for the prediction of photovoltaic power.Studies should explore the improvement of cumulus parameterisation schemes to enhance the accuracy of solar radiation component estimation and prediction under cloudy conditions.展开更多
Changes in wetland ecosystems have a critical impact on the local ecology and species diversity.Different development scenarios and policies are key factors influencing their changes.Therefore,we studied changes of we...Changes in wetland ecosystems have a critical impact on the local ecology and species diversity.Different development scenarios and policies are key factors influencing their changes.Therefore,we studied changes of wetlands in the middle Yangtze River basin(MYRB)in 2001-2020,and a patch-generated land use simulation(PLUS)model and random forest(RF)method were applied to predict and analyze the changes under different scenarios in the MYRB in the future(i.e.2035-2095).The results indicated that:(1)The regions with high wetland proportions were concentrated in the central and eastern MYRB in 2001-2020,with a 1.5%decrease in overall wetland area;(2)The RF could simulate the future ecological quality with training and testing accuracies of 0.98 and 0.92,respectively;(3)Remote Sensing Ecological Index(RSEI)less than 0.5 in the central and eastern regions and 13.3%reduction in the northwest in the SSP245 scenario.In general,the study provides a basis for future regional studies of ecosystem quality and provides data to support wetland conservation and management.展开更多
The ratio of leaf carotenoid to chlorophyll(Car/Chl)is an indicator of vegetation photosynthesis,development and responses to stress.However,the correlation between Car and Chl,and their overlapping absorption in the ...The ratio of leaf carotenoid to chlorophyll(Car/Chl)is an indicator of vegetation photosynthesis,development and responses to stress.However,the correlation between Car and Chl,and their overlapping absorption in the visible spectral domain pose a challenge for optical remote sensing of their ratio.This study aims to investigate combinations of vegetation indices(VIs)to minimize the influence of Car-Chl correlation,thus being more sensitive to the variability in the ratio across vegetation species and sites.VIs sensitive to Car and Chl variability were combined into four candidates of combinations,using a simulated dataset from the PROSPECT model.The VI combinations were then tested using six simulated datasets with different Car-Chl correlations,and evaluated against four independent datasets.The ratio of the carotenoid triangle ratio index(CTRI)with the red-edge chlorophyll index(CIred-edge)was found least influenced by the Car-Chl correlation and demonstrated a superior ability for estimating Car/Chl variability.Compared with published VIs and two machine learning algorithms,CTRI/CIred-edge also showed the optimal performance in the fourfield datasets.This new VI combination could be useful to provide insights in spatiotemporal variability in the leaf Car/Chl ratio,applicable for assessing vegetation physiology,phenology,and response to environmental stress.展开更多
The Yellow River Basin (YRB) is a vital ecological zone in China owing to its sensitive and fragile environment.Under the long-term influence of climate changes and artificial factors,the relationship between precipit...The Yellow River Basin (YRB) is a vital ecological zone in China owing to its sensitive and fragile environment.Under the long-term influence of climate changes and artificial factors,the relationship between precipitation,vegetation,and surface water in the YRB has changed drastically,ultimately affecting the water resources and environmental management.Therefore,we applied multivariate statistical analysis to investigate the precipitation,normalized difference vegetation index (NDVI),and surface water changes in the YRB from 2000to 2021.Furthermore,we attempted to clarify the ecological effects of precipitation by explaining the relationship between precipitation and vegetation in terms of the time-lag relationship using the Integrated Multi-satellite Retrievals for Global Precipitation Measurement algorithm,Moderate Resolution Imaging Spectroradiometer,and hydrological databases.Precipitation,vegetation,and area of surface water in the YRB showed increasing trends from 2000–2021 (e.g.,7.215 mm/yr,0.004 NDVI/yr,and 0.932 km^(2)/yr,respectively).The water level in the upper reaches of the YRB showed a downward trend,whereas that in the middle and lower reaches exhibited an upward trend.Changes in precipitation had a positive effect on vegetation and surface water in the YRB,with correlation coefficients of 0.63 and0.51,respectively.The responses of NDVI and surface water elevation to precipitation were heterogeneous and delayed,with the majority showing a lag time of approximately≤16 days.Moreover,the lag times of Longyangxia Lake and Ngoring-Co Lake were 0 and 8 days,respectively.We showed that precipitation variability can effectively explain vegetation improvement and increases in surface water elevation,while providing a proven scenario for predicting the surface water and vegetation productivity under the influence of climate change.展开更多
1 EXTREME DROUGHT AND HYDROGEODESY TECHNOLOGIES The World Meteorological Organization has officially declared 2023 as the hottest year on record,with the average global temperature surpassing pre-industrial(1850-1900)...1 EXTREME DROUGHT AND HYDROGEODESY TECHNOLOGIES The World Meteorological Organization has officially declared 2023 as the hottest year on record,with the average global temperature surpassing pre-industrial(1850-1900)average by 1.45℃.While temperature is not the only climate observable from the complex processes for the geneses of droughts,recent hottest years have witnessed numerous instances of extreme droughts.展开更多
基金supported in part by the Key Laboratory of Natural Resources Monitoring and Supervision in Southern Hilly Region,Ministry of Natural Resources(NRMSSHR2023Y02)Yunnan Key Laboratory of Plateau Geographic Processes and Environmental Changes(PGPEC2304)+1 种基金Yunnan Normal University,China.This study was also sponsored by the Scientific Research Project of Education Department of Hubei Province(Grant No.B2022262)the Philosophy and Social Sciences Research Project of Education Department of Hubei Province(Grant No.22G024).
文摘The continuous decrease of low-slope cropland resources caused by construction land crowding poses huge threat to regional sustainable development and food security.Slope spectrum analysis of topographic and geomorphic features is considered as a digital terrain analysis method which reflects the macro-topographic features by using micro-topographic factors.However,pieces of studies have extended the concept of slope spectrum in the field of geoscience to construction land to explore its expansion law,while research on the slope trend of cropland from that perspective remains rare.To address the gap,in virtue of spatial analysis and geographically weighted regression(GWR)model,the cropland use change in the Yangtze River Basin(YRB)from 2000 to 2020 was analyzed and the driving factors were explored from the perspective of slope spectrum.Results showed that the slope spectrum curves of cropland area-frequency in the YRB showed a first upward then a downward trend.The change curve of the slope spectrum of cropland in each province(municipality)exhibited various distribution patterns.Quantitative analysis of morphological parameters of cropland slope spectrum revealed that the further down the YRB,the stronger the flattening characteristics,the more obvious the concentration.The province experienced the greatest downhill cropland climbing(CLC)was Shannxi,while province experienced the highest uphill CLC was Zhejiang.The most common cropland use change type in the YRB was horizontal expansion type.The factors affecting average cropland climbing index(ACCI)were quite stable in different periods,while population density(POP)changed from negative to positive during the study period.This research is of practical significance for the rational utilization of cropland at the watershed scale.
基金supported by the National Natural Science Foundation of China(Grants No.42371354,42375129)Fundamental Research Funds for National University,China University of Geosciences,Wuhan(Grant No.CUGDCJJ202201).
文摘Climate change threatens China’s rice production,making it crucial to assess the impact of climate change and climate year type(CYT)on rice production across regions to safeguard food security.The impact of climate change under nine CYTs with different combinations of temperature and precipitation on two rice cropping systems,including single rice and double rice(early and late rice)was evaluated.The results indicate that:(1)the Northeast region was expected to undergo the greatest warming of 2.03–2.48℃,and future climate conditions would be dominated by Warm-Humid,Warm-Normal,and Warm-Dry CYTs across all regions.(2)Climate change would significantly shorten anthesis days after sowing and maturity days after sowing of single rice by 6–12 days and 9–24 days,with little change observed for late rice(<1 day).Late rice yield suffered more from climate change compared to single and early rice yield,declining by 8.8%–16.13%.(3)Different CYTs exhibited varying impacts on rice yields.Yields were projected to decrease by approximately 4.765%to 18.645%in Warm-Humid,Warm-Normal,and Warm-Dry CYTs.Conversely,the Northeast region was anticipated to experience an increase in yield.(4)Relationships between rice yield and meteorological factors varied by region,variety,and CYT.Among the nine CYTs,high killing degree days,mean daily temperature,mean solar radiation and warm spell duration index were the main factors influencing changes in rice yield,explaining nearly 80%of yield change.Our results would help to develop adaptation strategies in different regions and rice cropping systems.
基金This research was supported in part by grants from the Natural Science Foundation of China(Grant No.42371258 and 42001187)The project was also supported by the Key Laboratory of Natural Resources Monitoring and Supervision in Southern Hilly Region,Ministry of Natural Resources(NRMSSHR2023Y02)Yunnan Key Laboratory of Plateau Geographic Processes and Environmental Changes,Faculty of Geography,Yunnan Normal University(PGPEC2304).
文摘In recent decades,the spatio-temporal patterns of China’s croplands have been reshaped by disturbances from anthropogenic activities,with complex changes in the topographic characteristics of croplands.Slope-climbing of croplands(SCCL)is an important issue that threatens sustainable agricultural development.While providing land with prominent location advantages,SCCL weakens the water and fertilizer retention capacity for cropland,intensifies various geological disasters,and adversely affects the ecological environment and food yield of these croplands.It is crucial to determine the spatio-temporal variation features and effects of SCCL in China to formulate more accurate cropland protection policies and to maintain food security;however,the current lack of relevant studies is detrimental for capturing trends in cropland resources and sustainable cropland use.In this study,we constructed a multi-scale slope spectrum for cropland and total terrain to explore the spatial differences and trends of SCCL from a three-dimensional view.We evaluated the natural and socioeconomic effects of SCCL in China from multiple perspectives.Results indicate that the proportion of cropland with slopes below 2°,5°,and 6°in China decreased by 0.43%,0.47%,and 0.50%from 1980 to 2020,respectively.SCCL became apparent during 1980-1990 and 2010-2020,especially over the recent decade.The cropland climbing index(CCI)and upper limited slope change(ULSC)to measure the spatio-temporal pattern of SCCL were 0.99%and 1.17°,respectively,during 2010-2020.At the agricultural regional scale,the SCCL was also concentrated in 1980-1990 and 2010-2020,and it is more pronounced in the southern areas.The proportion of provinces and prefecture-level cities with high-intensity SCCL during 1980-2020 were 87.10%and 49.73%,respectively.SCCL was comparatively more pronounced and broader from 2010 to 2020.During this period,17.84%of prefecture-level cities had no SCCL,and the average CCI for all prefecture-level cities peaked at 1.62%.In this study,we also evaluated the pros and cons of SCCL and provided targeted suggestions for decision makers and farmers to refine cropland protection policy systems and further develop the sustainable use of croplands.
基金sponsored in part by the National Natural Science Foundation of China (Grant No.42001187)Scientific Research Project of Education Department of Hubei Province (No.B2022262)。
文摘Cropland elevation uplift(CLEU) has recently become a new challenge for agricultural modernization,food security,and sustainable cropland use in China.Uncovering the rules of CLEU is of great theoretical and practical significance for China’s sustainable agricultural development and rural revitalization strategy.However,existing studies lack in-depth disclosure of multi-scale CLEU evolution rules,making it difficult to support the formulation of specific cropland protection policies.We analyzed the spatio-temporal evolution and multiscale CLEU in China from 1980 to 2020 using the Lorenz curve,gravity center model,hotspot analysis,and cropland elevation spectrum.The results indicated that the center of gravity of cropland moved to the northeast from 1980 to 2000 and then shifted to the northwest.The spatial distribution of cropland became increasingly imbalanced from 1980 to 2000.The change hotspots clustered in the northwest and the northeast,whereas cold-spots were mainly in southeastern China.The average elevation of cropland increased by 17.38 m,and the elevation uplift rule in different regions differed evidently across scales.From 1980 to 2000,all provinces except Xinjiang,Inner Mongolia,Gansu,and Yunnan exhibited CLEU,with Qinghai,Tibet,Beijing,and Guangdong showing the most noticeable uplifting.The CLEU can alleviate the shortage of cropland to some extent.However,without a planning constraint,the CLEU will lead to the increase of ecological risk and food security risk.
基金National Natural Science Foundation of China,No.42207078CUG Scholar-Scientific Research Funds at China University of Geosciences(Wuhan),No.2022166+1 种基金China Scholarship Council,No.202306410026Opening Fund of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,China Institute of Water Resources and Hydropower Research,No.IWHR-SKL-KF202217。
文摘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 2020.Utilizing 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.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 41925007, 42001314, 41771360, 41975044 & 41801021)the Fundamental Research Funds for National UniversitiesChina University of Geosciences, Wuhan and China Scholarship Council。
文摘The response of agricultural productivity anomalies to drought stress plays a crucial role in the carbon cycle within terrestrial ecosystems and in ensuring food security. However, detailed analysis of how global agricultural productivity anomalies response to drought stress, particularly within irrigated and rainfed agricultural systems, remains insufficient. In this study, the impact of drought stress on agricultural productivity anomalies during the growing season(zcNDVI^(S)), across both irrigated and rainfed agriculture, were analyzed using a suite of hydro-climatic variables. Specifically, the investigation utilized the multi-scalar Standardized Precipitation Evapotranspiration Index(SPEI), the Multivariate ENSO Index(MEI), and the Madden-Julian Oscillation(MJO). Meanwhile, the relationships between hydroclimatic variables and zcNDVI^(S) were analyzed at one, two, three and four months before the ending of growing season(EOS). Results showed that(1) the percentages of significant(p<0.1) drying trends varied across the globe from 8.30% to 13.42%, 6.50% to 14.63%, 6.52% to 14.23%, and 6.47%to 14.95% at one-, two-, three-, and four-month lead times before EOS, respectively, during 2001–2020, which represented by the multiscalar SPEI. This observation highlights that most regions across the globe tend to be arid, which could significantly impact agricultural productivity;(2) the global mean correlation coefficients(rmax) for SPEI-1, SPEI-3, SPEI-6, SPEI-12(indicating SPEI at 1-, 3-, 6-, and 12-month lags), MEI, and MJO with zcNDVI^(S) ranged between 0.24–0.25, 0.27–0.28, 0.25–0.26, 0.21–0.22, –0.02–0.01 and 0.06–0.11, respectively, across both irrigated and rainfed agriculture system from 2001 to 2020.Agricultural productivity anomalies demonstrated a significant correlation with drought stress. The strongest correlations were noted for SPEI-3 and SPEI-6, suggesting a delayed response of crops to drought conditions. This indicates that agriculture ecosystem experiences prolonged disturbances due to abiotic drought stress;and(3) the percentages of regions that showed significant correlations(p<0.1) between zcNDVI^(S)and drought indices(SPEI-1, SPEI-3, SPEI-6, and SPEI-12), as well as climate indices(MEI and MJO) ranged as follows: 14.77%–20.27%, 21.51%–32.55%, 22.60%–35.68%, 21.89%–35.16%,7.93%–11.20% and 9.44%–17.94%. Quantitatively identifying how zcNDVI^(S) spatially responds to hydro-climatic variables can help us better understand the impact of drought on agricultural productivity anomalies worldwide.
基金supported by the National Natural Science Foundation of China(Grants No.42371354,42375129,42371115)the Fundamental Research Funds for National Universities,China Uni-versity of Geosciences,Wuhan.
文摘In recent years,there has been a pronounced increase in the frequency of extreme weather events.To compre hensively examine the impact of extreme weather on ecosystem services within the Wuhan Urban Agglomera tion(WUA),this study utilized meteorological station data,the Mann-Kendall(MK)test,and the Standardized Precipitation-Evapotranspiration Index(SPEI)to quantify the variation trends in heatwaves(HW)and droughts from 1961 to 2020.Then the Integrated Valuation of Ecosystem Services and Trade-offs(InVEST)model was employed to evaluate and compare the differences in water yield and climate regulation ecosystem services un der various HW,droughts,and HW-drought combination scenarios.The results show that over the past 60 years,the temperature,duration,and frequency of HW have significantly increased in the WUA.Specifically,the high est HW temperature,total HW days,HW frequency,and average HW temperature showed changing trend of+0.17℃/decade,+1.4 day/decade,+0.19 event/decade,and+0.07℃/decade,respectively.The year 2000 was identified as a mutation year for HW,characterized by increased frequency and heightened severity thereafter.The SPEI value exhibited an insignificant upward trend,with 1980 marked as a mutation year,indicating a de creasing trend in drought occurrences after 1980.Heatwaves have a weakening effect on both water yield and climate regulation services,while drought significantly weakened water yield and had a relatively modest effect on climate regulation.During HW-drought composite period,the average monthly water yield showed a notable discrepancy of 60 mm compared to humid years.Besides,as heatwaves intensify,the area of low aggregation for ecosystem services expands,whereas the area of high aggregation decreases.This study provides a preliminary understanding of the impact of urban extreme weather on urban ecosystem services under changing climatic conditions.
基金supported by the National Natural Science Foundation of China(41975044,41925007,42371354,42375129,and 41801021)Fundamental Research Funds for National University,China University of Geosciences,Wuhan(CUGDCJJ202201).
文摘Compared with physical models,WRF-Solar,as an excellent numerical forecasting model,includes abundant novel cloud physical and dynamical processes,which enablesenable the high-frequency output of radiation components which are urgently needed by the solar energy industry.However,the popularisation of WRF-Solar in a wide range of applications,such as the estimation of diffuse radiation,suffers from unpredictable influences of cloud and aerosol optical property parameters.This study assessed the accuracy of the improved numerical weather prediction(WRF-Solar)model in simulating global and diffuse radiation.Aerosol optical properties at 550 nm,which were provided by a moderate resolution imaging spectroradiometer,were used as input to analyse the differences in accuracies obtained by the model with/without aerosol input.The sensitivity of WRF-Solar to aerosol and cloud optical properties and solar zenith angle(SZA)was analysed.The results show the superiority of WRF-Solar to WRF-Dudhia in terms of their root mean square error(RMSE)and mean absolute error(MAE).The coefficients of determination between WRF-Solar and WRF-Dudhia revealed no statistically significant difference,with values greater than 0.9 for the parent and nested domains.In addition,the relative RMSE(RRMSE%)reached 46.60%.The experiment on WRF-Solar and WRF-Dudhia revealed a negative bias for global radiation,but WRF-Solar attained a slightly lower RMSE and higher correlation coefficient than WRF-Dudhia.The WRF-Solar-simulated results on diffuse radiation under clear sky conditions were slightly poorer,with RMSE,RRMSE,mean percentage error and MAE of 181.93 W m^(−2),170.52%,93.04%and 138 W m^(−2),respectively.Based on Himawari-8 cloud data,statistical results on cloud optical thickness(COT)for cloudy days revealed that WRF-Solar overestimated diffuse radiation at COTs greater than 20.Moreover,when the aerosol optical depth was greater than or equal to 0.8,WRF-Solar also overestimated the diffuse radiation,with a mean difference of 58.57 W m^(−2).The errors of WRF-Solar simulations in global and diffuse radiation exhibited a significant dependence on the SZA.The dispersion degree of deviation increased gradually with the decrease in the SZA.Thus,WRF-Solar serves as an improved numerical tool that can provide high temporal and high-spatial-resolution solar radiation data for the prediction of photovoltaic power.Studies should explore the improvement of cumulus parameterisation schemes to enhance the accuracy of solar radiation component estimation and prediction under cloudy conditions.
基金supported by Open Research Fund of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin(China Institute of Water Resources and Hydropower Research)[grant number IWHR-SKL-202217]Open Fund of National Engineering Research Center for Geographic Information System,China University of Geosciences[grant number 2021KFJJ01]National Nature Science Foundation of China[grant number 42171047].
文摘Changes in wetland ecosystems have a critical impact on the local ecology and species diversity.Different development scenarios and policies are key factors influencing their changes.Therefore,we studied changes of wetlands in the middle Yangtze River basin(MYRB)in 2001-2020,and a patch-generated land use simulation(PLUS)model and random forest(RF)method were applied to predict and analyze the changes under different scenarios in the MYRB in the future(i.e.2035-2095).The results indicated that:(1)The regions with high wetland proportions were concentrated in the central and eastern MYRB in 2001-2020,with a 1.5%decrease in overall wetland area;(2)The RF could simulate the future ecological quality with training and testing accuracies of 0.98 and 0.92,respectively;(3)Remote Sensing Ecological Index(RSEI)less than 0.5 in the central and eastern regions and 13.3%reduction in the northwest in the SSP245 scenario.In general,the study provides a basis for future regional studies of ecosystem quality and provides data to support wetland conservation and management.
基金supported by the National Natural Science Foundation of China(42001314)the Open Research Fund of the State Laboratory of Information Engineering in Surveying,Mapping,and Remote Sensing,Wuhan University(grant number 20R02)+1 种基金Torbern Tagesson was additionally funded by the Swedish National Space Agency(SNSA 2021-00144)FORMAS(Dnr.2021-00644).
文摘The ratio of leaf carotenoid to chlorophyll(Car/Chl)is an indicator of vegetation photosynthesis,development and responses to stress.However,the correlation between Car and Chl,and their overlapping absorption in the visible spectral domain pose a challenge for optical remote sensing of their ratio.This study aims to investigate combinations of vegetation indices(VIs)to minimize the influence of Car-Chl correlation,thus being more sensitive to the variability in the ratio across vegetation species and sites.VIs sensitive to Car and Chl variability were combined into four candidates of combinations,using a simulated dataset from the PROSPECT model.The VI combinations were then tested using six simulated datasets with different Car-Chl correlations,and evaluated against four independent datasets.The ratio of the carotenoid triangle ratio index(CTRI)with the red-edge chlorophyll index(CIred-edge)was found least influenced by the Car-Chl correlation and demonstrated a superior ability for estimating Car/Chl variability.Compared with published VIs and two machine learning algorithms,CTRI/CIred-edge also showed the optimal performance in the fourfield datasets.This new VI combination could be useful to provide insights in spatiotemporal variability in the leaf Car/Chl ratio,applicable for assessing vegetation physiology,phenology,and response to environmental stress.
基金The National Key Research and Development Program of China,No.2021YFC3201102National Natural Science Foundation of China,No.42207078Joint Open Research Fund Program of State Key Laboratory of Hydroscience and Engineering and Tsinghua-Ningxia Yinchuan Joint Institute of Internet of Waters on Digital Water Governance,No.sklhse-2022-Iow04。
文摘The Yellow River Basin (YRB) is a vital ecological zone in China owing to its sensitive and fragile environment.Under the long-term influence of climate changes and artificial factors,the relationship between precipitation,vegetation,and surface water in the YRB has changed drastically,ultimately affecting the water resources and environmental management.Therefore,we applied multivariate statistical analysis to investigate the precipitation,normalized difference vegetation index (NDVI),and surface water changes in the YRB from 2000to 2021.Furthermore,we attempted to clarify the ecological effects of precipitation by explaining the relationship between precipitation and vegetation in terms of the time-lag relationship using the Integrated Multi-satellite Retrievals for Global Precipitation Measurement algorithm,Moderate Resolution Imaging Spectroradiometer,and hydrological databases.Precipitation,vegetation,and area of surface water in the YRB showed increasing trends from 2000–2021 (e.g.,7.215 mm/yr,0.004 NDVI/yr,and 0.932 km^(2)/yr,respectively).The water level in the upper reaches of the YRB showed a downward trend,whereas that in the middle and lower reaches exhibited an upward trend.Changes in precipitation had a positive effect on vegetation and surface water in the YRB,with correlation coefficients of 0.63 and0.51,respectively.The responses of NDVI and surface water elevation to precipitation were heterogeneous and delayed,with the majority showing a lag time of approximately≤16 days.Moreover,the lag times of Longyangxia Lake and Ngoring-Co Lake were 0 and 8 days,respectively.We showed that precipitation variability can effectively explain vegetation improvement and increases in surface water elevation,while providing a proven scenario for predicting the surface water and vegetation productivity under the influence of climate change.
基金funded by the National Natural Science Fund of China(Nos.42442015,42274111)。
文摘1 EXTREME DROUGHT AND HYDROGEODESY TECHNOLOGIES The World Meteorological Organization has officially declared 2023 as the hottest year on record,with the average global temperature surpassing pre-industrial(1850-1900)average by 1.45℃.While temperature is not the only climate observable from the complex processes for the geneses of droughts,recent hottest years have witnessed numerous instances of extreme droughts.
