Soil organic carbon(SOC):total nitrogen(TN):total phosphorus(TP)(C:N:P)stoichiometry can give important information about biogeochemical cycling in terrestrial ecosystems.The spatial patterns and driving mechanisms of...Soil organic carbon(SOC):total nitrogen(TN):total phosphorus(TP)(C:N:P)stoichiometry can give important information about biogeochemical cycling in terrestrial ecosystems.The spatial patterns and driving mechanisms of soil C:N:P ratios are still poorly understood on the Qinghai-Tibetan Plateau of China.In this study,we therefore combined data of the geography,climate,soil properties,and vegetation characteristics from 319 sites across the plateau to investigate their relationships with the horizontal and vertical patterns of SOC,TN,and TP concentrations and their stoichiometric ratios(C:N and N:P).We observed higher SOC(30.5–46.8 mg g^(-1)),TN(2.4–3.4 mg g^(-1)),C:N(14.7–18.0),and N:P(6.9–8.0)in alpine meadows,forests,and shrublands and higher TP(1.6 mg g^(-1))in croplands.Overall,SOC,TN,TP,C:N,and N:P showed decreasing trends(by 67%,64%,19%,12%,and 54%,respectively)along the whole soil profile(0–100 cm).Soil cation exchange capacity and bulk density were the stronger environmental drivers of SOC and TN.Soil TP showed latitudinal and longitudinal increasing trends in all soil layers.Soil properties explained most of the variations in SOC(67%–90%),TN(67%–87%),C:N(61%–89%),and N:P(64%–85%),with increasing impacts along the soil profile.Geography and climate influenced soil TP directly and indirectly through their impacts on soil properties,with geography being the predominant driver(46%–65%)along the soil profile.The variation in soil C:N was mostly driven by SOC and TN,and the direct and indirect effects of the environmental factors were relatively weak.Geography,climate,soil properties,and vegetation characteristics indirectly impacted soil N:P through their impacts on TN and TP in all the soil layers.Altogether,our findings illuminate the relative contributions of geography,climate,soil properties,and vegetation characteristics to soil C:N and N:P,thus enhancing our understanding of C,N,and P cycling across the Qinghai-Tibetan Plateau.展开更多
This paper analyzes the role of the National Natural Science Foundation of China（NSFC） in advancing human geography in China by focusing on five key research areas： land use, urban systems and urban agglomeration, ...This paper analyzes the role of the National Natural Science Foundation of China（NSFC） in advancing human geography in China by focusing on five key research areas： land use, urban systems and urban agglomeration, economic globalization, climate change and social and cultural geographies. All NSFC-funded human geography programs related to these five topics from 1986 to 2017 comprise the sample for analysis, and the research topics, content, teams, and peer-reviewed journal publications supported by these programs are investigated. Specifically, this paper analyzes the NSFC＇s promotion of the expansion of research topics in response to national developmental needs and the shifting frontiers of human geography research internationally, its enhancement of interdisciplinary research, and its contributions to the assembly of specialized research teams. The paper also reports important progress in Chinese human geography over the past 30 years through the institutional lens of the NSFC, revealing major characteristics and trends in the discipline. The paper concludes by calling for further collaboration between the research community and the NSFC for the development of a locally suitable and globally influential Chinese human geography.展开更多
As an important branch of human geography, transportation geography has experienced three periods of evolution: foundation, systematization, and rapid development of the discipline. It has gradually become a relativel...As an important branch of human geography, transportation geography has experienced three periods of evolution: foundation, systematization, and rapid development of the discipline. It has gradually become a relatively mature discipline. During the period 1930– 1980, the development of transportation geography consisted mainly of the publication of theoretical texts. During 1980–2000, it gradually became a systematic discipline. Since the start of the 21 st century, transportation geography has focused mainly on exploring the impacts of transportation on socio-economic development. Currently, studies on transportation geography have led to significant developments in a number of areas, including transportation theory, facility distribution and planning, transportation flows and network analysis, evaluation of transport modes, transportation planning, and simulation and assessment of urban transportation. Such studies have also enriched human geography research, provided a wider geographical overview and elucidated the development mechanism of transportation, as well as helped to understand the impacts of transport development on socio-economic systems. Some findings obtained by geographers have been widely used in transportation geography and related fields, including the four basic laws of transportation generation, the hub–spoke mode of transport organization, the subordinating and guiding functions of transportation on socio-economic development, regional transport dominance measures, accessibility measures, and spatial organization of port systems.展开更多
Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing...Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing intensification of agricultural practices and negative natural factors,black soils are confronting enhanced degradation.The holistic overview of black soil degradation and the underlying mechanisms for soil health improvement will be key for agricultural sustainability and food security.In this review,the current status and driving factors of soil degradation in the four major black soil regions of the world are summarized,and effective measures for black soil conservation are proposed.The Northeast Plain of China is the research hotspot with 41.5%of the published studies related to black soil degradation,despite its relatively short history of agricultural reclamation,followed by the East European Plain(28.3%),the Great Plains of North America(20.7%),and the Pampas of South American(7.9%).Among the main types of soil degradation,soil erosion and soil fertility decline(especially organic matter loss)have been reported as the most common problems,with 27.6%and 39.4%of the published studies,respectively.In addition to the natural influences of climate and topography,human activities have been reported to have great influences on the degradation of black soils globally.Unsustainable farming practices and excess in agrochemical applications are common factors reported to accelerate the degradation process and threaten the sustainable use of black soils.Global efforts for black soil conservation and utilization should focus on standardizing evaluation criteria including real-time monitoring and the measures of prevention and restoration for sustainable management.International cooperation in technology and policy is crucial for overcoming the challenges and thus achieving the protection,sustainable use,and management of global black soil resources.展开更多
Nitrogen(N)enrichment has resulted in widespread alteration of grassland ecosystem processes and functions mainly through disturbance in soil enzyme activities.However,we lack a comprehensive understanding of how N de...Nitrogen(N)enrichment has resulted in widespread alteration of grassland ecosystem processes and functions mainly through disturbance in soil enzyme activities.However,we lack a comprehensive understanding of how N deposition affects specific key soil enzymes that mediate plant-soil feedback of grassland.Here,with a meta-analysis on 1446 cases from field observations in China,we show that N deposition differently affects soil enzymes associated with soil biochemical processes.Specifically,N-promoted C,N,and P-acquiring hydrolase activities significantly increased by 8.73%,7.67%,and 8.69%,respectively,related to an increase in microbial-specific enzyme secretion.The increased relative N availability and soil acidification were two potential mechanisms accounting for the changes in soil enzyme activities with N enrichment.The mixed N addition in combination of NH_(4)NO_(3) and urea showed greater stimulation effect on soil enzyme activities.However,the high rate and long-term N addition tended to weaken the positive responses of soil C-,Nand P-acquiring hydrolase activities to N enrichment.Spatially increased mean annual precipitation and temperature primarily promoted the positive effects of N enrichment on N-and P-acquiring hydrolase activities,and the stimulation of C-and N-acquiring hydrolase activities by N enrichment was intensified with the increase in soil depth.Finally,multimodal inference showed that grassland type was the most important regulator of responses of microbial C,N,and P-acquiring hydrolase activities to N enrichment.This meta-analysis provides a comprehensive insight into understanding the key role of N enrichment in shaping soil enzyme activities of grassland ecosystems.展开更多
The conversion of forests to pastures is the most important human intervention that has shaped the natural landscape into the Anthropocene environment.The Qinghai-Tibet Plateau(QTP),which has both forest drought-lines...The conversion of forests to pastures is the most important human intervention that has shaped the natural landscape into the Anthropocene environment.The Qinghai-Tibet Plateau(QTP),which has both forest drought-lines and alpine treelines with specific ecotone structures,including isolated trees in treeless plant-covers that represent ever existed forest cover according to‘Lonely Tooth Hypothesis’,offers an excellent model in which to examine the extent and timing of human activity on the conversion of forest to pasture.The objectives of this paper are to review(1)palaeo-environmental records of the Early Holocene that indicate when forests were first converted to‘alpine meadows’,and(2)current records of the changing treeline ecotone in the region.‘Alpine meadows’of the QTP are part of the largest conversion of mountain forests into pastures worldwide.This change in forest cover is possibly a consequence of the agro-pastoral transition and the dawn of the Anthropocene on the QTP.To date,however,there is an interdisciplinary gap in knowledge of 5000 years between the palaeo-ecological and the archaeolocical and zoo-archaeological records.Rapid changes of the rural economy and the exodus from remote highland villages to down-country cities have diminished the age-old impacts of summer grazing and pasture management by fire;reforestation is obvious,but often seen exclusively as an effect of Anthropocene global warming.We believe that more interdisciplinary collaborations on the QTP are necessary to increase our understanding of the treelines of the Anthropocene in High Asia.展开更多
To explore water level variations and their dynamic influence on the water quality of Huayang Lakes,the water level from 1967 to 2023 and water quality from 2015 to 2023 were analyzed using the Mann–Kendall trend tes...To explore water level variations and their dynamic influence on the water quality of Huayang Lakes,the water level from 1967 to 2023 and water quality from 2015 to 2023 were analyzed using the Mann–Kendall trend test,box plots,and violin plots.The results show a notable hydrological rhythm of water level alternation between dry and flood seasons in Huayang Lakes,with an average water level of 12.82 m and a monthly range of 11.21–17.24m.Since 2017,the water level of Huayang Rivers has shown a decreasing trend of–0.02 m/a.Total phosphorus(TP)has become the primary pollutant.The TP concentrations in Longgan Lake(the largest lake)during the dry,rising,flood,and retreating seasons from 2015 to 2023were 0.083,0.061,0.050,and 0.059 mg/L,respectively.The effect of water level on TP was mainly observed during the low-water period.When the water level in the dry season rose to 12.25 and 13.00 m,the percentage of TP exceeding 0.1 mg/L in Longgan Lake decreased to 55.8%and 33.3%,respectively.During the dry season,wind and wave disturbances caused the release of endogenous phosphorus in Huayang Lakes.This led to drastic fluctuations in TP concentration,reducing the correlation between water level and TP.When external control is limited,the water level during the dry season should be maintained between 12.25 and 13.0 m.Additionally,it is necessary to accelerate the restoration of submerged macrophyte species(such as Hydrilla verticillata and Vallisneria natans)in the Huayang Rivers.展开更多
The copper complexing of dissolved organic matter released from hydrochar(HDOM)affects the former’s environmental behavior.In this study,how hydrothermal temperatures(180,220 and 260℃)influence the molecular-level c...The copper complexing of dissolved organic matter released from hydrochar(HDOM)affects the former’s environmental behavior.In this study,how hydrothermal temperatures(180,220 and 260℃)influence the molecular-level constitutions and Cu(II)binding features of HDOM were elucidated via fourier transform ion cyclotron resonance mass spectrometry and multi-spectroscopic analysis.The findings demonstrated that the almost HDOM molecules had the traits of lower polarity and higher hydrophobicity.As the hydrothermal temperature increased,the molecules with particularly high relative strength gradually disappeared,average molecular weight,percentages of CHON and aliphatic compounds of HDOM reduced while the percentages of CHO and aromatic compounds increased.In general,the fluorescence quenching of Cu(II)weakened as hydrothermal temperature rose and the Cu(II)binding stability constants of fluorophores in HDOM were 4.50–5.31.In addition,the Cu(II) binding order of fluorophores in HDOM showed temperature heterogeneities, andpolysaccharides or aromatic rings of non-fluorescent substances had the fastest responsesto Cu(II) binding. Generally, fluorescent components tend to bind Cu(II) at relatively traceconcentrations (0–40 μmol/L), whereas non-fluorescent substances tend to the bind Cu(II)at relatively higher concentrations (50–100 μmol/L). This study contributed to the predictionof the potential environmental behaviors and risks of Cu(II) at the molecular level afterhydrochar application.展开更多
[Objective]Precipitation events caused by Super Typhoon Doksuri in Fujian Province were simulated and evaluated based on the WRF model to provide a reference for typhoon precipitation simulation and forecasting in sou...[Objective]Precipitation events caused by Super Typhoon Doksuri in Fujian Province were simulated and evaluated based on the WRF model to provide a reference for typhoon precipitation simulation and forecasting in southeast coastal areas of China.[Methods]The next-generation mesoscale numerical weather prediction model WRF V4.3(The Weather Research and Forecasting Model)was used to simulate the precipitation caused by Typhoon Doksuri in Fujian Province in 2023.Observations from 86 meteorological stations with hourly rainfall records were used to evaluate the model’s performance.Six evaluation indices were used,including the correlation coefficient(R),root mean square error(RMSE),mean absolute error(MAE),equitable threat score(ETS),probability of detection(POD),and false alarm ratio(FAR).[Results](1)The temporal and spatial evolution of precipitation during Typhoon Doksuri was effectively captured by the WRF model.Precipitation intensity increased gradually from July 27 to 29,2023,with the heaviest rainfall concentrated in the northern and eastern coastal areas of Fujian Province.(2)Significant differences in model performance were observed in terms of R,RMSE,and MAE.The largest errors occurred in Putian City,while smaller errors were found in southwestern Fujian Province.The evaluation result of all six indices showed that the WRF model performed best in simulating daily precipitation compared to hourly,three-hourly,six-hourly,and twelve-hourly precipitation.(3)The R95p index indicated that the WRF model successfully captured the overall spatial distribution of extreme precipitation.However,extreme precipitation intensity was overestimated in certain coastal areas.(4)Despite accurately identifying the coastal regions of Fujian as being most affected,the WRF model failed to accurately simulate the spatial distribution and intensity of precipitation.The simulated precipitation centers showed discrepancies when compared with the observed centers.[Conclusion]Although the WRF model underestimated hourly precipitation,it successfully captured the temporal evolution and spatial distribution of rainfall caused by Typhoon Doksuri in Fujian Province.It reproduced the heavy rainfall centers in central Fujian Province,with daily precipitation peaks reaching up to 350 mm.This highlighted the severity of extreme rainfall caused by Typhoon Doksuri.展开更多
Landslides represent a growing global challenge,particularly in mountainous and rapidly urbanising regions where environmental degradation and socio-economic vulnerabilities converge.This study investigates the interr...Landslides represent a growing global challenge,particularly in mountainous and rapidly urbanising regions where environmental degradation and socio-economic vulnerabilities converge.This study investigates the interrelationships between Integrated Landslide Disaster Risk Management(ILDRiM)and the United Nations Sustainable Development Goals(SDGs),advancing a systemsbased understanding of landslide risk as a socially constructed and development-driven phenomenon.Drawing on a narrative literature review and a Design Structure Matrix(DSM),the research identifies eight critical drivers of landslide disaster risk:deforestation,climate change,urbanisation,infrastructure development,community vulnerability,exposure to landslides,ineffective governance,and lack of scientific integration into policymaking.The DSM framework systematically maps these drivers against the 17 SDGs to evaluate the nature and strength of their interactions.The analysis reveals significant synergies,where addressing specific drivers supports multiple SDGs,and trade-offs,where risk reduction efforts may inadvertently hinder other development objectives if not implemented inclusively and strategically.Findings underscore the transformative potential of embedding ILDRiM within national and local development frameworks.Prioritising governance reform,scientific innovation,and resilient infrastructure(SDGs 16,17,and 9)is particularly effective for advancing landslide risk reduction while supporting broader sustainability outcomes.The study also highlights the need for anticipatory,cross-sectoral,and community-driven approaches to risk governance.This research offers actionable insights for policymakers,practitioners,and researchers seeking to align disaster risk management with sustainable development planning.It proposes a novel methodology for assessing systemic interlinkages between disaster risk drivers and the SDGs.It calls for further research to refine data integration,address context-specific risks,and strengthen the evidence base for risk-informed development.By operationalising ILDRiM through the SDG framework,this study supports creating more resilient,equitable,and sustainable communities in landslide-prone regions.展开更多
Water scarcity frequently contributes to wetland degradation or functional loss.Although agricultural drainage can alleviate water deficits,this often comes at the cost of disrupting native vegetation succession and a...Water scarcity frequently contributes to wetland degradation or functional loss.Although agricultural drainage can alleviate water deficits,this often comes at the cost of disrupting native vegetation succession and altering community structures.In the Songnen Plain of Northeast China,Bolboschoenus planiculmis,a dominant species in saline-alkaline wetlands,provides crucial food for the endangered Siberian crane(Grus leucogeranus).These wetlands,currently threatened by drought,increasingly rely on agricultural drainage for restoration.Previous research has focused on water table change and soil salinization effects,often overlooking the impacts of agricultural drainage-induced water environment changes.A two-year field study was conducted in the Momoge National Natural Reserve on the Songnen Plain,Northeast China from May to August in 2019 and 2020 to examine water environment parameters,vegetation growth,and reproduction characteristics,aiming to identify key factors influencing the plant community.Results reveal spatial heterogeneity in the plant community,with significant correlation between biomass,species diversity,tuber characteristics,and water parameters(P<0.05),albeit with some annual variations.Redundancy analysis identifies water depth,nitrate nitrogen,dissolved oxygen,total dissolved solids,and total phosphorus as primary determinants of community changes(P<0.05).Structural equation modelling demonstrates that water depth directly negatively affects species diversity and reproduction,while indirectly influencing productivity through its direct influence on water salinization.Phosphorus and nitrogen contents positively affect diversity and reproduction,exhibiting a trade-off relationship.These findings highlight the significant impact of agricultural drainage-induced water environment changes on community dynamics,with water parameters collectively influencing species diversity and reproduction through their synergistic and trade-off effects.This study provides valuable scientific insights for optimizing agricultural drainage management and facilitating ecological function restoration amidst ongoing global environmental changes.展开更多
Urban vitality is one of the key indicators of sustainable urban development and an important factor for shrinking cities to achieve internal optimization.The relationship between the built environment and urban vital...Urban vitality is one of the key indicators of sustainable urban development and an important factor for shrinking cities to achieve internal optimization.The relationship between the built environment and urban vitality has been extensively discussed.However,the moderating effect of housing vacancy on the built environment’s effect on urban vitality in shrinking cities has not been explored in detail.This paper selected Yichun District in Yichun City of Heilongjiang Province,a typical shrinking city in Northeast China,as the study area,focusing on the effect of the built environment on urban vitality in shrinking cities based on residential and commercial electricity consumption data for 2013 and 2018.Moreover,this study also explored the moderating mechanisms of residential and commercial housing vacancies on the built environment’s effect on urban vitality.The results demonstrate that the spatial pattern of urban vitality in the Yichun District is‘high in the center and low in the periphery’.Population density,building age,road density,and catering facilities are recognized as the main built environment factors affecting the vitality of shrinking cities.Residential and commercial housing vacancies have a significant moderating effect on the built environment’s effect on urban vitality.Residential housing vacancies enhance the positive effect of road density and the negative effect of greening rate.In addition,commercial housing vacancies suppress the positive effect of building density and enhance the positive effect of accessibility to urban service facilities.The study indicates that built environment factors exhibit heterogeneous effects on vitality in the context of urban shrinkage,as moderated by housing vacancies.Targeted regulation of built environment factors is of practical significance in realizing the internal development and vitality enhancement of shrinking cities.展开更多
Recently,the outbreak and spread of larch caterpillar(Dendrolimus superans)pests have emerged as significant contributors to forest degradation in the Changbai Mountains,China.Understanding the spatiotemporal distribu...Recently,the outbreak and spread of larch caterpillar(Dendrolimus superans)pests have emerged as significant contributors to forest degradation in the Changbai Mountains,China.Understanding the spatiotemporal distribution patterns of these pests is crucial for effective management and protection of forest ecosystems.This study proposes a pest monitoring approach based on Sentinel imagery.Through time-series analysis,we extracted pest-sensitive features and developed a random forest classifier that integrated Sentinel-1,Sentinel-2,and field sampling data from 2019–2023 to monitor larch caterpillar pests in the Changbai Mountains National Nature Reserve(CMNNR),Northeast China.Our findings indicated that bands green(B3),near-infrared(B8),short wave infrared(B11 and B12)from Sentinel-2 remote sensing images exhibited notable discriminative capabilities for identifying larch caterpillar pests.Specifically,the Normalized Difference Vegetation Index(NDVI)at the end of the growing season emerged as the most valuable feature for pest extraction.Incorporating Synthetic Aperture Radar(SAR)features along with optical data marginally enhances model performance.Furthermore,our approach unveiled the outbreak of larch caterpillar pests,achieving classification map with overall accuracy exceeding 85%and Kappa coefficient surpassing 0.8 for five study years.The pest outbreak began in 2019 and progressively intensified over time.In September 2019,the affected area spanned 114.23 km^(2).The infested area exhibited a declining trend from 2020 to 2023.This study introduces a novel method for the high-precision identification of larch caterpillar pests,offering technical advancements and theoretical underpinnings to support forest management strategies.展开更多
Dissolved organic matter(DOM)represents the largest pool of reactive carbon on the Earth and plays a crucial role in various biogeochemical processes and ecosystem functions.However,it is understudied for a global und...Dissolved organic matter(DOM)represents the largest pool of reactive carbon on the Earth and plays a crucial role in various biogeochemical processes and ecosystem functions.However,it is understudied for a global understanding of DOM molecular properties such as molecular weight,stoichiometry,and oxidation state,and the linkages among them across Earth systems.Here,a meta-analysis of 2707 sites in 204 literatures was conducted by synthesizing four representative molecular properties of DOM,i.e.,mass,double bond equivalent(DBE),modified aromaticity index(AI_(mod)),and nominal oxidation state of carbon(NOSC).By exploring H/C and O/C ratios,we examined the relationships among these DOM properties across waters and land systems,and their geographical patterns and environmental drivers.We found that,compared to land system,the mass,DBE,and AI_(mod) were all significantly higher in water systems,with river sediments exhibiting the highest values.The DOM oxidation state indicated by NOSC was greater on average in wastewater(NOSC=0.226±0.06)and marine water(NOSC=0.133±0.06)than in other habitats.Compared to waters,the mass in land system showed more strongly positive correlations with oxidation states such as NOSC and O/C,and the NOSC showed stronger relations to bioavailability properties such as DBE,AI_(mod),and H/C.Among all the properties,H/C and AI_(mod) contributed to the most variations in global DOM properties.In waters,NOSC monotonically increased towards high latitudes,while DBE and AI_(mod) showed significant hump-shaped patterns indicating peaked unsaturation and aromaticity at mid-latitudes of approximately absolute 30°–50°.The variations in DOM properties were significantly correlated with environmental factors such as annual mean temperature and pH.Collectively,we revealed the spatial distribution and environmental drivers of DOM molecular properties across Earth ecosystems,which could shed light on our comprehensive understanding of DOM characteristics and its dynamics.展开更多
Smallholder farming in West Africa faces various challenges, such as limited access to seeds, fertilizers, modern mechanization, and agricultural climate services. Crop productivity obtained under these conditions var...Smallholder farming in West Africa faces various challenges, such as limited access to seeds, fertilizers, modern mechanization, and agricultural climate services. Crop productivity obtained under these conditions varies significantly from one farmer to another, making it challenging to accurately estimate crop production through crop models. This limitation has implications for the reliability of using crop models as agricultural decision-making support tools. To support decision making in agriculture, an approach combining a genetic algorithm (GA) with the crop model AquaCrop is proposed for a location-specific calibration of maize cropping. In this approach, AquaCrop is used to simulate maize crop yield while the GA is used to derive optimal parameters set at grid cell resolution from various combinations of cultivar parameters and crop management in the process of crop and management options calibration. Statistics on pairwise simulated and observed yields indicate that the coefficient of determination varies from 0.20 to 0.65, with a yield deviation ranging from 8% to 36% across Burkina Faso (BF). An analysis of the optimal parameter sets shows that regardless of the climatic zone, a base temperature of 10˚C and an upper temperature of 32˚C is observed in at least 50% of grid cells. The growing season length and the harvest index vary significantly across BF, with the highest values found in the Soudanian zone and the lowest values in the Sahelian zone. Regarding management strategies, the fertility mean rate is approximately 35%, 39%, and 49% for the Sahelian, Soudano-sahelian, and Soudanian zones, respectively. The mean weed cover is around 36%, with the Sahelian and Soudano-sahelian zones showing the highest variability. The proposed approach can be an alternative to the conventional one-size-fits-all approach commonly used for regional crop modeling. Moreover, it has the potential to explore the performance of cropping strategies to adapt to changing climate conditions.展开更多
Urban lakes are vital components of the modern urban water system and landscape design.They play an important role in the construction of urban ecological civilization.However,in recent years,the urban lake ecosystem ...Urban lakes are vital components of the modern urban water system and landscape design.They play an important role in the construction of urban ecological civilization.However,in recent years,the urban lake ecosystem has been increasingly degraded,especially with the frequent cyanobacteria blooms,which directly threatens the maintenance of ecosystem service function and sustainable urban development.In this study,several sedimentary cores were collected from Hudie Lake located in the Yangtze River Delta in China that had not been dredged for centuries.Using one of the sediment cores that spans the past 200 years,we reconstructed the long-term environmental changes and examined the driving mechanisms of both human activities and natural factors affecting the lake's dynamics.Our results indicated that,with the growth of the city,organic matter and nutrients in the lake had gradually increased.Notably,the significant increase in phosphorus had been a key factor driving cyanobacteria blooms in Hudie Lake.Since the 1960s,urban development and changes in land use around the lake had severely disturbed its natural habitats,leading to peak nutrient levels during the period from 2000 to 2010.展开更多
The conversion of saline-alkali soils into paddy fields for long-term rice cultivation involves multiple disturbances,and as a result,soil microbial communities are altered to adapt to changing environmental condition...The conversion of saline-alkali soils into paddy fields for long-term rice cultivation involves multiple disturbances,and as a result,soil microbial communities are altered to adapt to changing environmental conditions.However,a comprehensive understanding of the succession of soil bacterial communities that occurs during this process is still lacking.In the present study,we utilized data obtained from paddy fields of different rice cultivation years(0-23 years)to investigate the compositional and functional succession of soil bacterial communities.We focused on core bacterial taxa that were specifically enriched at different successional stages.Generalized joint attribute modeling(GJAM)was used to identify core bacterial taxa.Results indicated that the bare saline-alkali soil(0 year,prior to any rice cultivation)shared few core amplicon sequence variants(ASVs)with paddy fields.In the bare saline-alkali soil,Longimicrobiaceae from the phylum Gemmatimonadetes was dominant,while the dominance was subsequently replaced by Burkholderiaceae and Pedosphaeraceae--phyla affiliated with Proteobacteria and Verrucomicrobia--after 5 and 23 years of rice cultivation,respectively.The relative abundances of nitrogen metabolism functions in the core bacterial communities of the bare saline-alkali soil were higher than those at other successional stages,while sulfur metabolism functions exhibited the opposite trend.These indicated that the role of the core bacterial taxa in mediating nutrient cycling also evolved and adapted to changing soil conditions as rice cultivation was established.Redundancy analysis(RDA)indicated that the composition of the core bacterial community in paddy fields with rice cultivation for 0,2 and 4,6,8,10,and 12,and 20 and 23 years were driven by soil nitrate nitrogen content,pH,available phosphorus content,and the ratio of total carbon to total nitrogen,respectively.In summary,the present study provides insights into the succession of soil bacterial communities and core bacterial taxa that occurs during long-term rice cultivation.展开更多
Understanding the coupling relationships among lake physicochemical properties,internal nutrient recycling,and related microbes is key for the control of freshwater eutrophication.In this study,seasonal variations in ...Understanding the coupling relationships among lake physicochemical properties,internal nutrient recycling,and related microbes is key for the control of freshwater eutrophication.In this study,seasonal variations in microorganisms at the sediment–water interface(SWI)of the eutrophic Lake Chaohu in China were analyzed,in order to reveal changes in phosphorus(P)-cycling-related microbes in the sediments and its association with internal P release during the cyanobacterial life cycle.The identified P-cycling-related microbes include phosphorus-solubilizing bacteria(PSB)(dominant of Bacillus,Thiobacillus and Acinetobacter),sulfate-reducing bacteria(SRB)(dominant of Sva0081_sediment_group,norank_c__Thermodesulfovibrionia and Desulfatiglans)and iron-reducing bacteria(FeRB)(dominant of Geothermobacter,Anaeromyxobacter,Thermoanaerobaculum and Clostridium_sensu_stricto_1).Increased PSB and reduced proportions of iron-aluminum–bound P(Fe/Al-P)and calcium–bound P(Ca-P)from the benthic stage to initial cyanobacterial growth indicated that internal phosphorus was released through the solubilization of Fe/Al-P and Ca-P by PSB.Growth of cyanobacteria was accompanied by cyanobacteria death,deposition,and degradation during early algal blooms,which increased SRB caused by high organic matter and the net deposition of phosphorus in the western lake.Conversely,phosphorus release in eastern lake was observed because of organic phosphorus mineralization.High linear discriminant analysis effect size of SRB and FeRB and the decreased Fe/Al-P in sediments indicated sulfide-mediated chemical iron reduction(SCIR)and FeRB-mediated microbial iron reduction mechanisms for internal phosphorus release during late algal blooms.The observed seasonal pattern of P-cycling-related microbes and its mediation on internal phosphorus release provides a foundation for internal P management in Lake Chaohu.展开更多
Deforestation remains one of the most imminent threats to biodiversity in the tropics.As such,its causes and dynamics need to be studied and understood to put a halt to further forest loss and degradation.In tropical ...Deforestation remains one of the most imminent threats to biodiversity in the tropics.As such,its causes and dynamics need to be studied and understood to put a halt to further forest loss and degradation.In tropical countries such as Uganda,agricultural expansion and wood fuel demand are its leading drivers.While the establishment of protected areas is a key tool in conserving remaining forest biodiversity,results indicate that current management does not sufficiently provide alternatives to forest resources utilised by households and income provided from timber and non-timber forest products.Beyond safeguarding ecosystems,protected areas need to ensure the sustainable socioeconomic development of adjacent communities for effective biodiversity conservation–however,both management and research often neglect to consider all dimensions.In this study,we analysed five decades of forest cover change in the Mount Elgon region,Uganda,by conducting a remote sensing analysis of its protected areas using Landsat MSS and TM data from 1973-2023 in combination with literature and subsequent interview analysis to consider both the ecological and socioeconomic dimension.We applied a random forest approach to differentiate forest and non-forest areas and carried out a pixel-based change detection analysis to differentiate temporal and spatial changes.Throughout the study period of 50 years,forest cover has evolved dynamically within the boundaries of the protected areas of Mount Elgon.A significant decline was observed in both Mount Elgon National Park with a loss of-5.98%(-46.83km²)and Mount Elgon Biosphere Reserve with a loss of-14.96%(-134.33km²).Our results showcase a cycle of deforestation and afforestation that could be tied to a series of development initiatives,re-demarcation of boundaries,changes in management and recurring evictions.Overall,the results lead to the conclusion that the lack of sustainable and efficient management and funding has fostered the rate of deforestation and accelerated ecological degradation in the region,but that existing problems are also rooted in the land tenure history of the region.We recommend the proper implementation of participatory and long-term management approaches on the ground and to address the land rights issue to contribute to both socioeconomic wellbeing and sustainable conservation outcomes.展开更多
Determining the pattern and mechanisms of species richness distribution at large spatial scales has been one of the core objectives in the field of ecology and biogeography.Although climate and soil effects on terrest...Determining the pattern and mechanisms of species richness distribution at large spatial scales has been one of the core objectives in the field of ecology and biogeography.Although climate and soil effects on terrestrial ecosystems are well-documented,largescale patterns in wetlands are poorly understood due to their unique hydrological processes and vegetation types.Here,we explored the pattern of plant species richness of Carex-dominated wetlands and its influencing mechanism in China based on a national field vegetation survey at 120 sites.Results showed that the community type and plant species richness of Carex-dominated wetlands differed significantly among different climate zones in China.The hierarchical partitioning analysis showed that community type and environmental context(spatial location,water regime,climate and soil conditions)together explained 41%of the variations in plant species richness,and community type had the greatest influence on species richness.Partial Least Squares Path Modeling result showed that plant species richness was directly affected by community type,climate factors,soil properties and water regime.Soil properties and water regime also indirectly affected plant species richness by directly affecting community type.These findings help us understand the pattern of plant diversity distribution in wetlands at large spatial scales and design effective conservation strategies for these valuable sedge meadow wetlands in a changing environment.展开更多
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program of China(No.2019QZKK0306-02)the National Natural Science Foundation of China(Nos.42322102 and 42271058)+1 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2021310)the Science&Technology Fundamental Resources Investigation Program of China(No.2022FY100202)
文摘Soil organic carbon(SOC):total nitrogen(TN):total phosphorus(TP)(C:N:P)stoichiometry can give important information about biogeochemical cycling in terrestrial ecosystems.The spatial patterns and driving mechanisms of soil C:N:P ratios are still poorly understood on the Qinghai-Tibetan Plateau of China.In this study,we therefore combined data of the geography,climate,soil properties,and vegetation characteristics from 319 sites across the plateau to investigate their relationships with the horizontal and vertical patterns of SOC,TN,and TP concentrations and their stoichiometric ratios(C:N and N:P).We observed higher SOC(30.5–46.8 mg g^(-1)),TN(2.4–3.4 mg g^(-1)),C:N(14.7–18.0),and N:P(6.9–8.0)in alpine meadows,forests,and shrublands and higher TP(1.6 mg g^(-1))in croplands.Overall,SOC,TN,TP,C:N,and N:P showed decreasing trends(by 67%,64%,19%,12%,and 54%,respectively)along the whole soil profile(0–100 cm).Soil cation exchange capacity and bulk density were the stronger environmental drivers of SOC and TN.Soil TP showed latitudinal and longitudinal increasing trends in all soil layers.Soil properties explained most of the variations in SOC(67%–90%),TN(67%–87%),C:N(61%–89%),and N:P(64%–85%),with increasing impacts along the soil profile.Geography and climate influenced soil TP directly and indirectly through their impacts on soil properties,with geography being the predominant driver(46%–65%)along the soil profile.The variation in soil C:N was mostly driven by SOC and TN,and the direct and indirect effects of the environmental factors were relatively weak.Geography,climate,soil properties,and vegetation characteristics indirectly impacted soil N:P through their impacts on TN and TP in all the soil layers.Altogether,our findings illuminate the relative contributions of geography,climate,soil properties,and vegetation characteristics to soil C:N and N:P,thus enhancing our understanding of C,N,and P cycling across the Qinghai-Tibetan Plateau.
文摘This paper analyzes the role of the National Natural Science Foundation of China（NSFC） in advancing human geography in China by focusing on five key research areas： land use, urban systems and urban agglomeration, economic globalization, climate change and social and cultural geographies. All NSFC-funded human geography programs related to these five topics from 1986 to 2017 comprise the sample for analysis, and the research topics, content, teams, and peer-reviewed journal publications supported by these programs are investigated. Specifically, this paper analyzes the NSFC＇s promotion of the expansion of research topics in response to national developmental needs and the shifting frontiers of human geography research internationally, its enhancement of interdisciplinary research, and its contributions to the assembly of specialized research teams. The paper also reports important progress in Chinese human geography over the past 30 years through the institutional lens of the NSFC, revealing major characteristics and trends in the discipline. The paper concludes by calling for further collaboration between the research community and the NSFC for the development of a locally suitable and globally influential Chinese human geography.
基金National Natural Science Foundation of China,No.41171107No.41371143
文摘As an important branch of human geography, transportation geography has experienced three periods of evolution: foundation, systematization, and rapid development of the discipline. It has gradually become a relatively mature discipline. During the period 1930– 1980, the development of transportation geography consisted mainly of the publication of theoretical texts. During 1980–2000, it gradually became a systematic discipline. Since the start of the 21 st century, transportation geography has focused mainly on exploring the impacts of transportation on socio-economic development. Currently, studies on transportation geography have led to significant developments in a number of areas, including transportation theory, facility distribution and planning, transportation flows and network analysis, evaluation of transport modes, transportation planning, and simulation and assessment of urban transportation. Such studies have also enriched human geography research, provided a wider geographical overview and elucidated the development mechanism of transportation, as well as helped to understand the impacts of transport development on socio-economic systems. Some findings obtained by geographers have been widely used in transportation geography and related fields, including the four basic laws of transportation generation, the hub–spoke mode of transport organization, the subordinating and guiding functions of transportation on socio-economic development, regional transport dominance measures, accessibility measures, and spatial organization of port systems.
基金funded by the Science and Technology Plan for the Belt and Road Innovation Cooperation Project of Jiangsu Province,China(No.BZ2023003)the National Key Research and Development Program of China(No.2021YFD1500202)+2 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA28010100)the“14th Five-Year Plan”Self-Deployment Project of the Institute of Soil Science,Chinese Academy of Sciences(No.ISSAS2418)the National Natural Science Foundation of China(No.42107334)。
文摘Black soils represent only one-sixth of the global arable land area but play an important role in maintaining world food security due to their high fertility and gigantic potential for food production.With the ongoing intensification of agricultural practices and negative natural factors,black soils are confronting enhanced degradation.The holistic overview of black soil degradation and the underlying mechanisms for soil health improvement will be key for agricultural sustainability and food security.In this review,the current status and driving factors of soil degradation in the four major black soil regions of the world are summarized,and effective measures for black soil conservation are proposed.The Northeast Plain of China is the research hotspot with 41.5%of the published studies related to black soil degradation,despite its relatively short history of agricultural reclamation,followed by the East European Plain(28.3%),the Great Plains of North America(20.7%),and the Pampas of South American(7.9%).Among the main types of soil degradation,soil erosion and soil fertility decline(especially organic matter loss)have been reported as the most common problems,with 27.6%and 39.4%of the published studies,respectively.In addition to the natural influences of climate and topography,human activities have been reported to have great influences on the degradation of black soils globally.Unsustainable farming practices and excess in agrochemical applications are common factors reported to accelerate the degradation process and threaten the sustainable use of black soils.Global efforts for black soil conservation and utilization should focus on standardizing evaluation criteria including real-time monitoring and the measures of prevention and restoration for sustainable management.International cooperation in technology and policy is crucial for overcoming the challenges and thus achieving the protection,sustainable use,and management of global black soil resources.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA28110300)National Natural Science Foundation of China(No.U23A2004)+3 种基金Natural Science Foundation of Jilin Province,China(No.YDZJ202201ZYTS522)Science and Technology Cooperation Program between Jilin Province and Chinese Academy of Sciences(No.2023SYHZ0053)Innovation Team Program of Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences(No.2023CXTD02)the European Commission under Marie Sk?odowska-Curie(No.101034371)。
文摘Nitrogen(N)enrichment has resulted in widespread alteration of grassland ecosystem processes and functions mainly through disturbance in soil enzyme activities.However,we lack a comprehensive understanding of how N deposition affects specific key soil enzymes that mediate plant-soil feedback of grassland.Here,with a meta-analysis on 1446 cases from field observations in China,we show that N deposition differently affects soil enzymes associated with soil biochemical processes.Specifically,N-promoted C,N,and P-acquiring hydrolase activities significantly increased by 8.73%,7.67%,and 8.69%,respectively,related to an increase in microbial-specific enzyme secretion.The increased relative N availability and soil acidification were two potential mechanisms accounting for the changes in soil enzyme activities with N enrichment.The mixed N addition in combination of NH_(4)NO_(3) and urea showed greater stimulation effect on soil enzyme activities.However,the high rate and long-term N addition tended to weaken the positive responses of soil C-,Nand P-acquiring hydrolase activities to N enrichment.Spatially increased mean annual precipitation and temperature primarily promoted the positive effects of N enrichment on N-and P-acquiring hydrolase activities,and the stimulation of C-and N-acquiring hydrolase activities by N enrichment was intensified with the increase in soil depth.Finally,multimodal inference showed that grassland type was the most important regulator of responses of microbial C,N,and P-acquiring hydrolase activities to N enrichment.This meta-analysis provides a comprehensive insight into understanding the key role of N enrichment in shaping soil enzyme activities of grassland ecosystems.
基金support of the German Research Council(DFG)since 1976 and the cooperation with Sichuan University,Yunnan University,and the Institutes of the Chinese Academy of Sciences(CAS)in Kunming,Chengdu,Lanzhou,Xining,and Beijing.Udo Schickhoff is also grateful to the DFG for funding treeline-related research(SCHI 436/14e1)the National Natural Science Foundation of China(grant numbers U20A2080 and 31622015)Sichuan University(Institutional Research Fund,2021SCUNL102,Fundamental Research Funds for the Central Universities,SCU 2022D003)。
文摘The conversion of forests to pastures is the most important human intervention that has shaped the natural landscape into the Anthropocene environment.The Qinghai-Tibet Plateau(QTP),which has both forest drought-lines and alpine treelines with specific ecotone structures,including isolated trees in treeless plant-covers that represent ever existed forest cover according to‘Lonely Tooth Hypothesis’,offers an excellent model in which to examine the extent and timing of human activity on the conversion of forest to pasture.The objectives of this paper are to review(1)palaeo-environmental records of the Early Holocene that indicate when forests were first converted to‘alpine meadows’,and(2)current records of the changing treeline ecotone in the region.‘Alpine meadows’of the QTP are part of the largest conversion of mountain forests into pastures worldwide.This change in forest cover is possibly a consequence of the agro-pastoral transition and the dawn of the Anthropocene on the QTP.To date,however,there is an interdisciplinary gap in knowledge of 5000 years between the palaeo-ecological and the archaeolocical and zoo-archaeological records.Rapid changes of the rural economy and the exodus from remote highland villages to down-country cities have diminished the age-old impacts of summer grazing and pasture management by fire;reforestation is obvious,but often seen exclusively as an effect of Anthropocene global warming.We believe that more interdisciplinary collaborations on the QTP are necessary to increase our understanding of the treelines of the Anthropocene in High Asia.
基金The Joint Research Project for Yangtze River Conservation,No.2022-LHYJ-02-0504-05-08Anhui Provincial Scientific Research Project for Universities,China No.2023AH050508。
文摘To explore water level variations and their dynamic influence on the water quality of Huayang Lakes,the water level from 1967 to 2023 and water quality from 2015 to 2023 were analyzed using the Mann–Kendall trend test,box plots,and violin plots.The results show a notable hydrological rhythm of water level alternation between dry and flood seasons in Huayang Lakes,with an average water level of 12.82 m and a monthly range of 11.21–17.24m.Since 2017,the water level of Huayang Rivers has shown a decreasing trend of–0.02 m/a.Total phosphorus(TP)has become the primary pollutant.The TP concentrations in Longgan Lake(the largest lake)during the dry,rising,flood,and retreating seasons from 2015 to 2023were 0.083,0.061,0.050,and 0.059 mg/L,respectively.The effect of water level on TP was mainly observed during the low-water period.When the water level in the dry season rose to 12.25 and 13.00 m,the percentage of TP exceeding 0.1 mg/L in Longgan Lake decreased to 55.8%and 33.3%,respectively.During the dry season,wind and wave disturbances caused the release of endogenous phosphorus in Huayang Lakes.This led to drastic fluctuations in TP concentration,reducing the correlation between water level and TP.When external control is limited,the water level during the dry season should be maintained between 12.25 and 13.0 m.Additionally,it is necessary to accelerate the restoration of submerged macrophyte species(such as Hydrilla verticillata and Vallisneria natans)in the Huayang Rivers.
基金supported by the National Natural Science Foundation of China(No.42307090)the Open Subject from State Environmental Protection Key Laboratory of Aquatic Ecosystem Health in theMiddle and Lower Reaches of Yangtze River(No.AEHKF2023008).
文摘The copper complexing of dissolved organic matter released from hydrochar(HDOM)affects the former’s environmental behavior.In this study,how hydrothermal temperatures(180,220 and 260℃)influence the molecular-level constitutions and Cu(II)binding features of HDOM were elucidated via fourier transform ion cyclotron resonance mass spectrometry and multi-spectroscopic analysis.The findings demonstrated that the almost HDOM molecules had the traits of lower polarity and higher hydrophobicity.As the hydrothermal temperature increased,the molecules with particularly high relative strength gradually disappeared,average molecular weight,percentages of CHON and aliphatic compounds of HDOM reduced while the percentages of CHO and aromatic compounds increased.In general,the fluorescence quenching of Cu(II)weakened as hydrothermal temperature rose and the Cu(II)binding stability constants of fluorophores in HDOM were 4.50–5.31.In addition,the Cu(II) binding order of fluorophores in HDOM showed temperature heterogeneities, andpolysaccharides or aromatic rings of non-fluorescent substances had the fastest responsesto Cu(II) binding. Generally, fluorescent components tend to bind Cu(II) at relatively traceconcentrations (0–40 μmol/L), whereas non-fluorescent substances tend to the bind Cu(II)at relatively higher concentrations (50–100 μmol/L). This study contributed to the predictionof the potential environmental behaviors and risks of Cu(II) at the molecular level afterhydrochar application.
文摘[Objective]Precipitation events caused by Super Typhoon Doksuri in Fujian Province were simulated and evaluated based on the WRF model to provide a reference for typhoon precipitation simulation and forecasting in southeast coastal areas of China.[Methods]The next-generation mesoscale numerical weather prediction model WRF V4.3(The Weather Research and Forecasting Model)was used to simulate the precipitation caused by Typhoon Doksuri in Fujian Province in 2023.Observations from 86 meteorological stations with hourly rainfall records were used to evaluate the model’s performance.Six evaluation indices were used,including the correlation coefficient(R),root mean square error(RMSE),mean absolute error(MAE),equitable threat score(ETS),probability of detection(POD),and false alarm ratio(FAR).[Results](1)The temporal and spatial evolution of precipitation during Typhoon Doksuri was effectively captured by the WRF model.Precipitation intensity increased gradually from July 27 to 29,2023,with the heaviest rainfall concentrated in the northern and eastern coastal areas of Fujian Province.(2)Significant differences in model performance were observed in terms of R,RMSE,and MAE.The largest errors occurred in Putian City,while smaller errors were found in southwestern Fujian Province.The evaluation result of all six indices showed that the WRF model performed best in simulating daily precipitation compared to hourly,three-hourly,six-hourly,and twelve-hourly precipitation.(3)The R95p index indicated that the WRF model successfully captured the overall spatial distribution of extreme precipitation.However,extreme precipitation intensity was overestimated in certain coastal areas.(4)Despite accurately identifying the coastal regions of Fujian as being most affected,the WRF model failed to accurately simulate the spatial distribution and intensity of precipitation.The simulated precipitation centers showed discrepancies when compared with the observed centers.[Conclusion]Although the WRF model underestimated hourly precipitation,it successfully captured the temporal evolution and spatial distribution of rainfall caused by Typhoon Doksuri in Fujian Province.It reproduced the heavy rainfall centers in central Fujian Province,with daily precipitation peaks reaching up to 350 mm.This highlighted the severity of extreme rainfall caused by Typhoon Doksuri.
基金DGAPA-UNAM for providing financial support to conduct landslide risk research through Project PAPIIT IN300823。
文摘Landslides represent a growing global challenge,particularly in mountainous and rapidly urbanising regions where environmental degradation and socio-economic vulnerabilities converge.This study investigates the interrelationships between Integrated Landslide Disaster Risk Management(ILDRiM)and the United Nations Sustainable Development Goals(SDGs),advancing a systemsbased understanding of landslide risk as a socially constructed and development-driven phenomenon.Drawing on a narrative literature review and a Design Structure Matrix(DSM),the research identifies eight critical drivers of landslide disaster risk:deforestation,climate change,urbanisation,infrastructure development,community vulnerability,exposure to landslides,ineffective governance,and lack of scientific integration into policymaking.The DSM framework systematically maps these drivers against the 17 SDGs to evaluate the nature and strength of their interactions.The analysis reveals significant synergies,where addressing specific drivers supports multiple SDGs,and trade-offs,where risk reduction efforts may inadvertently hinder other development objectives if not implemented inclusively and strategically.Findings underscore the transformative potential of embedding ILDRiM within national and local development frameworks.Prioritising governance reform,scientific innovation,and resilient infrastructure(SDGs 16,17,and 9)is particularly effective for advancing landslide risk reduction while supporting broader sustainability outcomes.The study also highlights the need for anticipatory,cross-sectoral,and community-driven approaches to risk governance.This research offers actionable insights for policymakers,practitioners,and researchers seeking to align disaster risk management with sustainable development planning.It proposes a novel methodology for assessing systemic interlinkages between disaster risk drivers and the SDGs.It calls for further research to refine data integration,address context-specific risks,and strengthen the evidence base for risk-informed development.By operationalising ILDRiM through the SDG framework,this study supports creating more resilient,equitable,and sustainable communities in landslide-prone regions.
基金Under the auspices of the National Key Research and Development Program of China(No.2022YFF1300900)the National Natural Science Foundation of China(No.41771108,41871102,42471066)+1 种基金the Science and Technology Development Program of Jilin Province of China(No.20230203003SF,20240602026RC)the Major Scientific and Technological Project of Jilin Province of China(No.20230303005SF)。
文摘Water scarcity frequently contributes to wetland degradation or functional loss.Although agricultural drainage can alleviate water deficits,this often comes at the cost of disrupting native vegetation succession and altering community structures.In the Songnen Plain of Northeast China,Bolboschoenus planiculmis,a dominant species in saline-alkaline wetlands,provides crucial food for the endangered Siberian crane(Grus leucogeranus).These wetlands,currently threatened by drought,increasingly rely on agricultural drainage for restoration.Previous research has focused on water table change and soil salinization effects,often overlooking the impacts of agricultural drainage-induced water environment changes.A two-year field study was conducted in the Momoge National Natural Reserve on the Songnen Plain,Northeast China from May to August in 2019 and 2020 to examine water environment parameters,vegetation growth,and reproduction characteristics,aiming to identify key factors influencing the plant community.Results reveal spatial heterogeneity in the plant community,with significant correlation between biomass,species diversity,tuber characteristics,and water parameters(P<0.05),albeit with some annual variations.Redundancy analysis identifies water depth,nitrate nitrogen,dissolved oxygen,total dissolved solids,and total phosphorus as primary determinants of community changes(P<0.05).Structural equation modelling demonstrates that water depth directly negatively affects species diversity and reproduction,while indirectly influencing productivity through its direct influence on water salinization.Phosphorus and nitrogen contents positively affect diversity and reproduction,exhibiting a trade-off relationship.These findings highlight the significant impact of agricultural drainage-induced water environment changes on community dynamics,with water parameters collectively influencing species diversity and reproduction through their synergistic and trade-off effects.This study provides valuable scientific insights for optimizing agricultural drainage management and facilitating ecological function restoration amidst ongoing global environmental changes.
基金Under the auspices of the National Natural Science Foundation of China(No.42171191,41771172,42201211,42401249)Science and Technology Development Plan Project of Jilin Province,China(No.20220508025RC)Young Scientist Group Project of Northeast Institute of Geography and Agroecology,Chinese Academy of Sciences(No.2022QNXZ02)。
文摘Urban vitality is one of the key indicators of sustainable urban development and an important factor for shrinking cities to achieve internal optimization.The relationship between the built environment and urban vitality has been extensively discussed.However,the moderating effect of housing vacancy on the built environment’s effect on urban vitality in shrinking cities has not been explored in detail.This paper selected Yichun District in Yichun City of Heilongjiang Province,a typical shrinking city in Northeast China,as the study area,focusing on the effect of the built environment on urban vitality in shrinking cities based on residential and commercial electricity consumption data for 2013 and 2018.Moreover,this study also explored the moderating mechanisms of residential and commercial housing vacancies on the built environment’s effect on urban vitality.The results demonstrate that the spatial pattern of urban vitality in the Yichun District is‘high in the center and low in the periphery’.Population density,building age,road density,and catering facilities are recognized as the main built environment factors affecting the vitality of shrinking cities.Residential and commercial housing vacancies have a significant moderating effect on the built environment’s effect on urban vitality.Residential housing vacancies enhance the positive effect of road density and the negative effect of greening rate.In addition,commercial housing vacancies suppress the positive effect of building density and enhance the positive effect of accessibility to urban service facilities.The study indicates that built environment factors exhibit heterogeneous effects on vitality in the context of urban shrinkage,as moderated by housing vacancies.Targeted regulation of built environment factors is of practical significance in realizing the internal development and vitality enhancement of shrinking cities.
基金Under the auspices of National Natural Science Foundation of China(No.42171407,42077242)Key Program of National Natural Science Foundation of China(No.42330607)。
文摘Recently,the outbreak and spread of larch caterpillar(Dendrolimus superans)pests have emerged as significant contributors to forest degradation in the Changbai Mountains,China.Understanding the spatiotemporal distribution patterns of these pests is crucial for effective management and protection of forest ecosystems.This study proposes a pest monitoring approach based on Sentinel imagery.Through time-series analysis,we extracted pest-sensitive features and developed a random forest classifier that integrated Sentinel-1,Sentinel-2,and field sampling data from 2019–2023 to monitor larch caterpillar pests in the Changbai Mountains National Nature Reserve(CMNNR),Northeast China.Our findings indicated that bands green(B3),near-infrared(B8),short wave infrared(B11 and B12)from Sentinel-2 remote sensing images exhibited notable discriminative capabilities for identifying larch caterpillar pests.Specifically,the Normalized Difference Vegetation Index(NDVI)at the end of the growing season emerged as the most valuable feature for pest extraction.Incorporating Synthetic Aperture Radar(SAR)features along with optical data marginally enhances model performance.Furthermore,our approach unveiled the outbreak of larch caterpillar pests,achieving classification map with overall accuracy exceeding 85%and Kappa coefficient surpassing 0.8 for five study years.The pest outbreak began in 2019 and progressively intensified over time.In September 2019,the affected area spanned 114.23 km^(2).The infested area exhibited a declining trend from 2020 to 2023.This study introduces a novel method for the high-precision identification of larch caterpillar pests,offering technical advancements and theoretical underpinnings to support forest management strategies.
基金supported by the National Natural Science Foundation of China(Nos.U24A20578,42225708,42377122,92251304)the Basic Research Program of Jiangsu Province(No.BK20240111)+1 种基金the Key Laboratory of Lake and Watershed Science for Water Security(No.NKL2023-QN04)the Science and Technology Planning Project of Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences(No.NIGLAS2022GS09).
文摘Dissolved organic matter(DOM)represents the largest pool of reactive carbon on the Earth and plays a crucial role in various biogeochemical processes and ecosystem functions.However,it is understudied for a global understanding of DOM molecular properties such as molecular weight,stoichiometry,and oxidation state,and the linkages among them across Earth systems.Here,a meta-analysis of 2707 sites in 204 literatures was conducted by synthesizing four representative molecular properties of DOM,i.e.,mass,double bond equivalent(DBE),modified aromaticity index(AI_(mod)),and nominal oxidation state of carbon(NOSC).By exploring H/C and O/C ratios,we examined the relationships among these DOM properties across waters and land systems,and their geographical patterns and environmental drivers.We found that,compared to land system,the mass,DBE,and AI_(mod) were all significantly higher in water systems,with river sediments exhibiting the highest values.The DOM oxidation state indicated by NOSC was greater on average in wastewater(NOSC=0.226±0.06)and marine water(NOSC=0.133±0.06)than in other habitats.Compared to waters,the mass in land system showed more strongly positive correlations with oxidation states such as NOSC and O/C,and the NOSC showed stronger relations to bioavailability properties such as DBE,AI_(mod),and H/C.Among all the properties,H/C and AI_(mod) contributed to the most variations in global DOM properties.In waters,NOSC monotonically increased towards high latitudes,while DBE and AI_(mod) showed significant hump-shaped patterns indicating peaked unsaturation and aromaticity at mid-latitudes of approximately absolute 30°–50°.The variations in DOM properties were significantly correlated with environmental factors such as annual mean temperature and pH.Collectively,we revealed the spatial distribution and environmental drivers of DOM molecular properties across Earth ecosystems,which could shed light on our comprehensive understanding of DOM characteristics and its dynamics.
文摘Smallholder farming in West Africa faces various challenges, such as limited access to seeds, fertilizers, modern mechanization, and agricultural climate services. Crop productivity obtained under these conditions varies significantly from one farmer to another, making it challenging to accurately estimate crop production through crop models. This limitation has implications for the reliability of using crop models as agricultural decision-making support tools. To support decision making in agriculture, an approach combining a genetic algorithm (GA) with the crop model AquaCrop is proposed for a location-specific calibration of maize cropping. In this approach, AquaCrop is used to simulate maize crop yield while the GA is used to derive optimal parameters set at grid cell resolution from various combinations of cultivar parameters and crop management in the process of crop and management options calibration. Statistics on pairwise simulated and observed yields indicate that the coefficient of determination varies from 0.20 to 0.65, with a yield deviation ranging from 8% to 36% across Burkina Faso (BF). An analysis of the optimal parameter sets shows that regardless of the climatic zone, a base temperature of 10˚C and an upper temperature of 32˚C is observed in at least 50% of grid cells. The growing season length and the harvest index vary significantly across BF, with the highest values found in the Soudanian zone and the lowest values in the Sahelian zone. Regarding management strategies, the fertility mean rate is approximately 35%, 39%, and 49% for the Sahelian, Soudano-sahelian, and Soudanian zones, respectively. The mean weed cover is around 36%, with the Sahelian and Soudano-sahelian zones showing the highest variability. The proposed approach can be an alternative to the conventional one-size-fits-all approach commonly used for regional crop modeling. Moreover, it has the potential to explore the performance of cropping strategies to adapt to changing climate conditions.
基金State Key Laboratory of Lake and Watershed Science for Water Security,No.2024SKL016National Natural Science Foundation of China,No.42002204,No.42373060+1 种基金Innovative Training Program for University Students,No.2024219,No.2024224Jiangsu Provincial Government Scholarship Program for Studying Abroad,No.2024-075。
文摘Urban lakes are vital components of the modern urban water system and landscape design.They play an important role in the construction of urban ecological civilization.However,in recent years,the urban lake ecosystem has been increasingly degraded,especially with the frequent cyanobacteria blooms,which directly threatens the maintenance of ecosystem service function and sustainable urban development.In this study,several sedimentary cores were collected from Hudie Lake located in the Yangtze River Delta in China that had not been dredged for centuries.Using one of the sediment cores that spans the past 200 years,we reconstructed the long-term environmental changes and examined the driving mechanisms of both human activities and natural factors affecting the lake's dynamics.Our results indicated that,with the growth of the city,organic matter and nutrients in the lake had gradually increased.Notably,the significant increase in phosphorus had been a key factor driving cyanobacteria blooms in Hudie Lake.Since the 1960s,urban development and changes in land use around the lake had severely disturbed its natural habitats,leading to peak nutrient levels during the period from 2000 to 2010.
基金supported by the National Natural Science Foundation of China(Nos.32371734,42007034,41920104008,and U22A20593)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA28020400)+2 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2023205)the Young Scientist Group Project of Northeast Institute of Geography and Agroecology of China(No.2022QNXZ04)the Science and Technology Development Project of Jilin Province of China(No.YDZJ202101ZYTS006).
文摘The conversion of saline-alkali soils into paddy fields for long-term rice cultivation involves multiple disturbances,and as a result,soil microbial communities are altered to adapt to changing environmental conditions.However,a comprehensive understanding of the succession of soil bacterial communities that occurs during this process is still lacking.In the present study,we utilized data obtained from paddy fields of different rice cultivation years(0-23 years)to investigate the compositional and functional succession of soil bacterial communities.We focused on core bacterial taxa that were specifically enriched at different successional stages.Generalized joint attribute modeling(GJAM)was used to identify core bacterial taxa.Results indicated that the bare saline-alkali soil(0 year,prior to any rice cultivation)shared few core amplicon sequence variants(ASVs)with paddy fields.In the bare saline-alkali soil,Longimicrobiaceae from the phylum Gemmatimonadetes was dominant,while the dominance was subsequently replaced by Burkholderiaceae and Pedosphaeraceae--phyla affiliated with Proteobacteria and Verrucomicrobia--after 5 and 23 years of rice cultivation,respectively.The relative abundances of nitrogen metabolism functions in the core bacterial communities of the bare saline-alkali soil were higher than those at other successional stages,while sulfur metabolism functions exhibited the opposite trend.These indicated that the role of the core bacterial taxa in mediating nutrient cycling also evolved and adapted to changing soil conditions as rice cultivation was established.Redundancy analysis(RDA)indicated that the composition of the core bacterial community in paddy fields with rice cultivation for 0,2 and 4,6,8,10,and 12,and 20 and 23 years were driven by soil nitrate nitrogen content,pH,available phosphorus content,and the ratio of total carbon to total nitrogen,respectively.In summary,the present study provides insights into the succession of soil bacterial communities and core bacterial taxa that occurs during long-term rice cultivation.
基金supported by the National Natural Science Foundation of China(No.U22A20616).
文摘Understanding the coupling relationships among lake physicochemical properties,internal nutrient recycling,and related microbes is key for the control of freshwater eutrophication.In this study,seasonal variations in microorganisms at the sediment–water interface(SWI)of the eutrophic Lake Chaohu in China were analyzed,in order to reveal changes in phosphorus(P)-cycling-related microbes in the sediments and its association with internal P release during the cyanobacterial life cycle.The identified P-cycling-related microbes include phosphorus-solubilizing bacteria(PSB)(dominant of Bacillus,Thiobacillus and Acinetobacter),sulfate-reducing bacteria(SRB)(dominant of Sva0081_sediment_group,norank_c__Thermodesulfovibrionia and Desulfatiglans)and iron-reducing bacteria(FeRB)(dominant of Geothermobacter,Anaeromyxobacter,Thermoanaerobaculum and Clostridium_sensu_stricto_1).Increased PSB and reduced proportions of iron-aluminum–bound P(Fe/Al-P)and calcium–bound P(Ca-P)from the benthic stage to initial cyanobacterial growth indicated that internal phosphorus was released through the solubilization of Fe/Al-P and Ca-P by PSB.Growth of cyanobacteria was accompanied by cyanobacteria death,deposition,and degradation during early algal blooms,which increased SRB caused by high organic matter and the net deposition of phosphorus in the western lake.Conversely,phosphorus release in eastern lake was observed because of organic phosphorus mineralization.High linear discriminant analysis effect size of SRB and FeRB and the decreased Fe/Al-P in sediments indicated sulfide-mediated chemical iron reduction(SCIR)and FeRB-mediated microbial iron reduction mechanisms for internal phosphorus release during late algal blooms.The observed seasonal pattern of P-cycling-related microbes and its mediation on internal phosphorus release provides a foundation for internal P management in Lake Chaohu.
基金The financial support by the Deutsche Bundesstiftung Umwelt (DBU)
文摘Deforestation remains one of the most imminent threats to biodiversity in the tropics.As such,its causes and dynamics need to be studied and understood to put a halt to further forest loss and degradation.In tropical countries such as Uganda,agricultural expansion and wood fuel demand are its leading drivers.While the establishment of protected areas is a key tool in conserving remaining forest biodiversity,results indicate that current management does not sufficiently provide alternatives to forest resources utilised by households and income provided from timber and non-timber forest products.Beyond safeguarding ecosystems,protected areas need to ensure the sustainable socioeconomic development of adjacent communities for effective biodiversity conservation–however,both management and research often neglect to consider all dimensions.In this study,we analysed five decades of forest cover change in the Mount Elgon region,Uganda,by conducting a remote sensing analysis of its protected areas using Landsat MSS and TM data from 1973-2023 in combination with literature and subsequent interview analysis to consider both the ecological and socioeconomic dimension.We applied a random forest approach to differentiate forest and non-forest areas and carried out a pixel-based change detection analysis to differentiate temporal and spatial changes.Throughout the study period of 50 years,forest cover has evolved dynamically within the boundaries of the protected areas of Mount Elgon.A significant decline was observed in both Mount Elgon National Park with a loss of-5.98%(-46.83km²)and Mount Elgon Biosphere Reserve with a loss of-14.96%(-134.33km²).Our results showcase a cycle of deforestation and afforestation that could be tied to a series of development initiatives,re-demarcation of boundaries,changes in management and recurring evictions.Overall,the results lead to the conclusion that the lack of sustainable and efficient management and funding has fostered the rate of deforestation and accelerated ecological degradation in the region,but that existing problems are also rooted in the land tenure history of the region.We recommend the proper implementation of participatory and long-term management approaches on the ground and to address the land rights issue to contribute to both socioeconomic wellbeing and sustainable conservation outcomes.
基金Under the auspices of National Key Research and Development Program of China(No.2023YFF1305800)National Natural Science Foundation of China(No.42494820,U23A2004,42077070)Youth Innovation Promotion Association Chinese Academy of Sciences(No.2019234,2020237)。
文摘Determining the pattern and mechanisms of species richness distribution at large spatial scales has been one of the core objectives in the field of ecology and biogeography.Although climate and soil effects on terrestrial ecosystems are well-documented,largescale patterns in wetlands are poorly understood due to their unique hydrological processes and vegetation types.Here,we explored the pattern of plant species richness of Carex-dominated wetlands and its influencing mechanism in China based on a national field vegetation survey at 120 sites.Results showed that the community type and plant species richness of Carex-dominated wetlands differed significantly among different climate zones in China.The hierarchical partitioning analysis showed that community type and environmental context(spatial location,water regime,climate and soil conditions)together explained 41%of the variations in plant species richness,and community type had the greatest influence on species richness.Partial Least Squares Path Modeling result showed that plant species richness was directly affected by community type,climate factors,soil properties and water regime.Soil properties and water regime also indirectly affected plant species richness by directly affecting community type.These findings help us understand the pattern of plant diversity distribution in wetlands at large spatial scales and design effective conservation strategies for these valuable sedge meadow wetlands in a changing environment.
