Understanding the local ecological security status and its underlying drivers can be used as an effective reference for balancing ecosystem development with societal needs. This study assesses the ecological security ...Understanding the local ecological security status and its underlying drivers can be used as an effective reference for balancing ecosystem development with societal needs. This study assesses the ecological security of the Loess Plateau(LP) by integrating ecosystem health and ecosystem services, explores the varying impacts of ecosystem structure, quality, and services on ecological security index(ESI), and identifies the key driving factors of ESI using the Geodetector model. The results show that:(1) the average ESI indicates a relatively safe ecological status in LP with a significant increase in ESI observed in 50.21% of the region, largely due to the ecological restoration programs.(2) Natural factors predominantly influence ESI, although human factors play a significant role in the earthy-rocky mountain region and plateau wind-sand region.(3) The interactions between driving factors have a much greater impact on ESI than any single factor, with the interactions between precipitation and human factors being the most influential combination. This study provides a novel perspective on assessing ecological security in LP. We recommend that future ecological restoration efforts should consider the varying roles of ecosystem structure, quality, and services in ESI while tailoring strategies to the primary driving factors based on local conditions.展开更多
The surface solar radiation in most parts of the world has undergone a phenomenon known as global dimming and brightening,characterized by an initial decrease followed by an increase.As a result,the sunshine duration(...The surface solar radiation in most parts of the world has undergone a phenomenon known as global dimming and brightening,characterized by an initial decrease followed by an increase.As a result,the sunshine duration(SD)has decreased in the past 60 years.Against the backdrop of global dimming and brightening,SD has decreased to varying degrees in many regions of China.Using the observed data of SD,cloud amount(total cloud amount and low cloud amount,abbreviated as TCA and LCA),precipitation,and relative humidity(RH)from 34 meteorological stations in Chongqing during the period of 1961-2020,along with a digital elevation model(DEM)with a resolution of 90 m,this study analyzed the spatiotemporal variations and influencing factors of SD.The analysis employed methods such as linear regression,Mann-Kendall test,wavelet transformation,and DEM-based possible SD distributed model.The results showed that the annual SD in Chongqing has significantly decreased over the last 60 years,with a decreasing interannual trend rate(ITR)of 40.4 h/10a.Except for no obvious trend in spring,SD decreased significantly in summer,autumn and winter at the ITR of 21.1 h/10a,8.5 h/10a and 7.5 h/10a,respectively.An abrupt decrease in the annual SD was found in 1979.The difference before and after the abrupt decrease was 177.7 h.The difference before and after the abrupt decrease was 177.7 h.The annual SD possessed the oscillation period of 11a.The spatial heterogeneity of the mean annual SD during the last 60 years was obvious.The distribution of SD in Chongqing is high in the northeast and low in the southeast.In addition,about 73%of the total area in Chongqing showed a significant and very significant decreasing trend.The regions with significant changes are mainly concentrated in the regions with altitudes of 200~1000 m.The increasing LCA was the main cause of the decrease of the annual SD in the regions with 200-400 m altitude decreased the most and changed the most.Increasing LCA is the primary cause of the reduction in annual SD,showing a strong negative correlation coefficient of-0.7292.In Chongqing,PM2.5 concentration showed a significant decrease trend in annual,spring,autumn and winter during 2000-2020,but the significant correlation between PM2.5 concentration and SD was only in autumn and reached an extremely significant level.展开更多
The long-term spatiotemporal changes of surface biogenic elements in the Changjiang River Estuary and adjacent waters during the summer of 2008–2016 were analyzed in this study.The concentrations of dissolved inorgan...The long-term spatiotemporal changes of surface biogenic elements in the Changjiang River Estuary and adjacent waters during the summer of 2008–2016 were analyzed in this study.The concentrations of dissolved inorganic nitrogen(DIN),soluble reactive phosphate(PO_(4)^(3−))and silicate(SiO_(3)^(2−))were generally stable,with a slight decrease of DIN and PO_(4)^(3−),and a slight increase of SiO_(3)^(2−),which mainly occurred in the estuarine waters.The grey correlation analysis was carried out between biogenic elements and chlorophyll a(Chl-a).Results showed that compared with the absolute values of biogenic elements,the correlations between the concentration ratio of nitrogen to phosphorus(N/P),ratio of silicon to nitrogen(Si/N)and Chl-a were closer,indicating the important influence on phytoplankton by the structure of biogenic elements.The study area was generally in a state of potential P limitation,and could have potential impact on the phytoplankton community,triggering the shift of red tide dominant species from diatoms to dinoflagellates.展开更多
The Three-River Headwaters Region （TRHR）, which is the source area of the Yangtze River, Yellow River, and Lancang River, is of key importance to the ecological secu- rity of China. Because of climate changes and hu...The Three-River Headwaters Region （TRHR）, which is the source area of the Yangtze River, Yellow River, and Lancang River, is of key importance to the ecological secu- rity of China. Because of climate changes and human activities, ecological degradation oc- curred in this region. Therefore, ＂The nature reserve of Three-River Sou,＇ce Regions＂ was established, and ＂The project of ecological protection and construction for the Three-River Headwaters Nature Reserve＂ was implemented by the Chinese government. This study, based on MODIS-NDVI and climate data, aims to analyze the spatiotemporal changes in vegetation coverage and its driving factors in the TRHR between 2000 and 2011, from three dimensions. Linear regression, Hurst index analysis, and partial correlation analysis were employed. The results showed the following： （1） In the past 12 years （2000-2011）, the NDVI of the study area increased, with a linear tendency being 1.2%/10a, of which the Yangtze and Yellow River source regions presented an increasing trend, while the Lancang River source region showed a decreasing trend. （2） Vegetation coverage presented an obvious spatial difference in the TRHR, and the NDVI frequency was featured by a bimodal structure. （3） The area with improved vegetation coverage was larger than the degraded area, being 64.06% and 35.94%, respectively during the study period, and presented an increasing trend in the north and a decreasing trend in the south. （4） The reverse characteristics of vegetation cov- erage change are significant. In the future, degradation trends will be mainly found in the Yangtze River Basin and to the north of the Yellow River, while areas with improving trends are mainly distributed in the Lancang River Basin. （5） The response of vegetation coverage to precipitation and potential evapotranspiration has a time lag, while there is no such lag in the case of temperature. （6） The increased vegetation coverage is mainly attributed to the warm-wet climate change and the implementation of the ecological protection project.展开更多
Sensitivity assessment is useful for monitoring land desertification. Research into how to prevent and control desertification is also important. In the arid region of northwest China, desertification is becoming wors...Sensitivity assessment is useful for monitoring land desertification. Research into how to prevent and control desertification is also important. In the arid region of northwest China, desertification is becoming worse and is a serious problem that affects local sustainable development. Based on remote-sensing and geographic information system technology, this study establishes a 'soil-terrain-hydrology-climate-vegetation' desertification sensitivity comprehensive evaluation system to reflect the spatiotemporal changes of land desertification, and proposes a spatial distance model to calculate a desertification sensitivity index. The spatiotemporal change characteristics of land desertification sensitivity in northwest China are quantitatively assessed from 2000 to 2017. Moreover, the main driving factors are analyzed using the geographical detector method. The results show the following.(1) Terrain, soil, climate, vegetation and hydrology affect and restrict each other, and constitute the background conditions of the distributions and changes of sensitivity to desertification in northwest China.(2) Desertification sensitivity generally displays a low distribution characteristic on the periphery of the area and a high one in the interior. The low-sensitivity regions are mainly in the five major mountain ranges(Altai Mountains, Tianshan Mountains, Kunlun Mountains, Altun Mountains and Qilian Mountains), while the high-sensitivity regions are mainly in regions such as the Junggar Basin, the Tarim Basin and the Inner Mongolia Plateau, as well as the Taklimakan Desert, Badain Jaran Desert and Tengger Desert. The spatial distribution of desertification sensitivity is obviously regional, and the high-and low-sensitivity regions have clear boundaries and a concentrated distribution.(3) With regard to spatiotemporal evolution, changes in desertification sensitivity since 2000 have been predominantly stable, and the overall sensitivity has displayed a slowly decreasing trend, indicating that potential desertification regions are decreasing annually and that some achievements have been made in the control of regional desertification.(4) Soil and climate play a direct role in the driving factors of desertification in northwest China, and these have been found to be the most important influential factors. Vegetation is the most active and basic factor in changing the sensitivity. In addition, topography and hydrology play a role in restricting desertification changes. Socio-economic factors are the most rapid factors affecting regional desertification sensitivity, and their impacts tend to be gradually increasing. In general, desertification has been effectively controlled in northwest China, and positive results have been achieved in such control. However, against the backdrop of intensified global climate change, increasingly prominent human activities and new normals of socio-economic development, the monitoring, assessment and control of desertification in China still have a long way to go.展开更多
Due to irrational human activities and extreme climate,the Qinghai-Xizang Plateau,China,faces a serious threat of desertification.Desertification has a detrimental effect on the ecological environment and socioeconomi...Due to irrational human activities and extreme climate,the Qinghai-Xizang Plateau,China,faces a serious threat of desertification.Desertification has a detrimental effect on the ecological environment and socioeconomic development.In this study,the desertification sensitivity index(DSI)model was established by integrating the spatial distance model and environmentally sensitive area index evaluation method,and then the model was used to quantitatively analyze the spatial and temporal characteristics of desertification sensitivity of the Qinghai-Xizang Plateau from 1990 to 2020.The results revealed that:(1)a general increasing tendency from southeast to northwest was identified in the spatial distribution of desertification sensitivity.The low-sensitivity areas were mostly concentrated in the Hengduan and Nyaingqêntanglha mountains and surrounding forest and meadow areas.The high-sensitivity areas were located mainly in the Kunlun and Altun mountains and surrounding decertified areas.The center of gravity of all types of desertification-sensitive areas moved to the northwest,and the desertification sensitivity showed a decreasing trend as a whole;(2)the area of highly sensitive desertification areas decreased by 8.37%,with extreme sensitivity being the largest change among the sensitivity types.The desertification sensitivity transfer was characterized by a greater shift to lower sensitivity levels(24.56%)than to higher levels(2.03%),which demonstrated a declining trend;(3)since 1990,the change in desertification sensitivity has been dominated by the stabilizing type Ⅰ(29.30%),with the area of continuously increasing desertification sensitivity accounting for only 1.10%,indicating that the management of desertification has achieved positive results in recent years;and(4)natural factors have had a more significant impact on desertification sensitivity on the Xizang Plateau,whereas socioeconomic factors affected only localized areas.The main factors influencing desertification sensitivity were vegetation drought tolerance and aridity index.Studying spatiotemporal variations in desertification sensitivity and its influencing factors can provide a scientific foundation for developing strategies to control desertification on the Qinghai-Xizang Plateau.Dividing different desertification-sensitive areas on the basis of these patterns of change can facilitate the formulation of more targeted management and protection measures,contributing to ecological construction and sustainable economic development in the area.展开更多
Social vulnerability,as one of the risk components,partially explains the magnitude of the impacts observed after a disaster.In this study,a spatiotemporally comparable assessment of social vulnerability and its drive...Social vulnerability,as one of the risk components,partially explains the magnitude of the impacts observed after a disaster.In this study,a spatiotemporally comparable assessment of social vulnerability and its drivers was conducted in Portugal,at the civil parish level,for three census frames.The first challenging step consisted of the selection of meaningful and consistent variables over time.Data were normalized using the Adjusted Mazziotta-Pareto Index(AMPI)to obtain comparable adimensional-normalized values.A joint principal component analysis(PCA)was applied,resulting in a robust set of variables,interpretable from the point of view of their self-grouping around vulnerability drivers.A separate PCA for each census was also conducted,which proved to be useful in analyzing changes in the composition and type of drivers,although only the joint PCA allows the monitoring of spatiotemporal changes in social vulnerability scores and drivers from 1991 to 2011.A general improvement in social vulnerability was observed for Portugal.The two main drivers are the economic condition(PC1),and aging and depopulation(PC2).The remaining drivers highlighted are uprooting and internal mobility,and daily commuting.Census data proved their value in the territorial,social,and demographic characterization of the country,to support medium-and long-term disaster risk reduction measures.展开更多
Mountain amphibians are exposed to a multitude of threats from climate change and anthropogenic disturbances. However, a lack of data hinders the understanding of the responses of mountain amphibians to these threats,...Mountain amphibians are exposed to a multitude of threats from climate change and anthropogenic disturbances. However, a lack of data hinders the understanding of the responses of mountain amphibians to these threats, which is becoming a conservation concern. Using frogs in the Hengduan Mountains, a biodiversity hotspot in Southwest China as indicators, we attempted to assess the extent and magnitude of changes in alpha diversity(species richness) and beta diversity(community turnover) between two periods(1930–2005 and 2006–2022). We compared elevational patterns for total, endemic and non-endemic frogs between the two periods, evaluated community turnover(i.e., S?rensen and Jaccard binary dissimilarity), and further quantified whether significant homogenization or differentiation of the frog communities occurred over time. Our results showed that the present species richness is greater than the historical species richness. The elevational patterns of total, endemic and non-endemic frogs were similar with slight changes across the two periods and clear increases in richness occurring at low and middle elevations. Although there was no significant biotic homogenization or differentiation over time, the community composition shifted dramatically. This study highlights the importance of assessing spatiotemporal changes in biodiversity in response to environmental changes and contributes to mountain species conservation as global change intensifies. We therefore call for greater efforts in community resurveys to assess biodiversity changes and provide useful insights for conservation strategies and action implementation.展开更多
Shaanxi province in China is rich in vegetation resources,making the study of vegetation phenology crucial for understanding climate change and ecological dynamics.Previous studies on Shaanxi have primarily focused on...Shaanxi province in China is rich in vegetation resources,making the study of vegetation phenology crucial for understanding climate change and ecological dynamics.Previous studies on Shaanxi have primarily focused on coarse-scale phenology,which results in the loss of essential spatial details due to the lack of finer-scale analyses.Moreover,the impact of rapid urbanisation on the phenology of various vegetation types in this region remains unclear.To address these gaps,we integrated Landsat and MODIS data to generate a daily 30 m NDVI sequence.Vegetation phenology across Shaanxi from 2000 to 2020 was then extracted and analysed,and the responses of different vegetation types to urbanisation were explored.Results indicated that accurate vegetation phenology can be obtained at a 30 m resolution,which is more precise than conventional coarse-scale investigations.The Start of Season(SOS)and End of Season(EOS)in the province advanced by-0.56 and-0.08 day/year,respectively,from 2000 to 2020.In general,the SOS gradually delays,and the EOS progressively advances with increasing latitude.However,anomalies were identified in regions south of 32.64°N and across the zone from 34.04°N to 37.56°N,which are primarily due to the effects of high elevation and rapid urbanisation,respectively.Further investigation into phenological differences among various vegetation types revealed that forests exhibit the earliest SOS,while grasslands present the latest.In addition,a significant negative correlation was found between the SOS difference and air temperature difference along the urban-rural gradient,with urbanisation having the most significant impact on cropland phenology.This study provides valuable insights into vegetation phenology and its response to urbanisation.These insights offer crucial information for ecological conservation and management strategies.展开更多
The dynamics of soil organic carbon(SOC)in cropland is one of the central issues related to both soil fertility and environmental safety. However, little information is available at county level regarding the spatiote...The dynamics of soil organic carbon(SOC)in cropland is one of the central issues related to both soil fertility and environmental safety. However, little information is available at county level regarding the spatiotemporal variability of SOC in the southwestern mountainous region of China. Thus, this study aimed to explore spatiotemporal changes of SOC in the cultivated soil layer of dry land in Mojiang County,Yunnan Province, China. Data were obtained from the second national soil survey(SNSS) of 1985 and soil tests for fertilizer application carried out by the Mojiang Agricultural Bureau in 2006. The ANOVA test was applied to determine any significant differences between the datasets, while semivariogram analysis was performed on geostatistics via an ordinary Kriging method in order to map spatial patterns of soil organic carbon density(SOCD). The results revealed that SOCD in the cultivated soil layer significantly decreased from 3.93 kg m^(-2) in 1985 to 2.89 kg m^(-2) in 2006, with a total soil organic carbon stock(SOCS) decrease of 41.54×10~4 t over the same period. SOCS levels fell most markedly in yellow-brown soil at a rate of51.52%, while an increase of 8.70% was found in the analysed latosol. Geostatistical analysis also showed that the recorded changes in SOCD between 1985 and2006 were spatially structured. The decreasing trend might be attributed to the combined action of intense cultivation, major crop residue removal without any protective tillage measures, unreasonable fertilization and natural climatic diversity inducing a large decrease in SOC in the studied cultivated dry land region of Mojiang County. Therefore, management measures such as protective tillage should be undertaken in order to enhance soil C sequestration.展开更多
Since the Grain for Green(GFG)program was implemented in 1999,most steeply sloping farmlands in the Loess Plateau of China have been returned to forestland and grassland.To understand its impact on the food production...Since the Grain for Green(GFG)program was implemented in 1999,most steeply sloping farmlands in the Loess Plateau of China have been returned to forestland and grassland.To understand its impact on the food production,this study analyzed the spatiotemporal changes of food crop production(FCP)in the plateau and quantified the contribution of sown area and yield changes to the total FCP during 1998–2014 using factor decomposition models,and then discussed the impact of GFG program on the FCP based on literature data.With the implementation of GFG program,total sown area in the Loess Plateau quickly deceased by 17.3%from 1998 to 2003,and then gradually restored to 1.03×107 hm2 in 2010.Thereafter,it slightly decreased to 1.02×107 hm2(94.6%of the area in 1998)in 2014.By contrast,total FCP generally showed an apparent growth trend,averagely increased by 1.71%per year in the whole plateau during 1998–2014.This increase was jointly contributed by the improved yield of individual crops,and the adjustment of cropping structure,i.e.,the expansion of high yield maize crop.The factor decomposition analysis results indicate that the sown area shrinkage only reduced the growth rate of total FCP by 0.29%per year during 1998–2014,although a significant impact was found for the early stage of 1999–2003.The results suggest that the implementation of GFG program would not induce an obvious risk of the food security.Therefore,it is suggested that the GFG program should be set as a long-term strategic policy,by not only supporting the conversion of slope farmlands,but also helping local farmers to seek sustainable ways of land use to improve the income and livelihood.It can be combined with the poverty eradication program,to simultaneously achieve the national goals of ecological civilization building and the livelihood improvement of rural people in the Loess Plateau.Considering rainfall limitation,the conversion of slope farmlands should be prioritized to grasslands.展开更多
Accurate and rapid evaluation of the regional eco-environment is critical to policy formulation.The remote sensing ecological index(RSEI)model of the Guangxi Beibu Gulf Economic Zone(GBGEZ)during 2001-2020 was establi...Accurate and rapid evaluation of the regional eco-environment is critical to policy formulation.The remote sensing ecological index(RSEI)model of the Guangxi Beibu Gulf Economic Zone(GBGEZ)during 2001-2020 was established and evaluated using four indices:dryness,wetness,greenness,and heat.This paper proposes an information granulation method for remote sensing based on the RSEI index value that uses granular computing.We found that:(1)From 2001 to 2020,the eco-environmental quality(EEQ)of GBGEZ tended to improve,and the spatial difference tended to expand.The regional spatial distribution of the eco-environment is primarily in the second-level and third-level areas,and the EEQ in the east and west is better than that in the middle.The contribution of greenness,wetness,and dryness to the improvement of EEQ in the study region increased year by year.(2)From 2001to 2020,the order of the contribution of the EEQ index in the GBGEZ was dryness,wetness,greenness,and heat.(3)The social and economic activities in the study region had a certain inhibitory effect on the improvement of the EEQ.展开更多
Agriculture needs to produce more food to feed the growing population in the 21st century.It makes the reference crop water requirement(WREQ)a major challenge especially in regions with limited water and high water de...Agriculture needs to produce more food to feed the growing population in the 21st century.It makes the reference crop water requirement(WREQ)a major challenge especially in regions with limited water and high water demand.Iran,with large climatic variability,is experiencing a serious water crisis due to limited water resources and inefficient agriculture.In order to overcome the issue of uneven distribution of weather stations,gridded Climatic Research Unit(CRU)data was applied to analyze the changes in potential evapotranspiration(PET),effective precipitation(EFFPRE)and WREQ.Validation of data using in situ observation showed an acceptable performance of CRU in Iran.Changes in PET,EFFPRE and WREQ were analyzed in two 30-a periods 1957-1986 and 1987-2016.Comparing two periods showed an increase in PET and WREQ in regions extended from the southwest to northeast and a decrease in the southeast,more significant in summer and spring.However,EFFPRE decreased in the southeast,northeast,and northwest,especially in winter and spring.Analysis of annual trends revealed an upward trend in PET(14.32 mm/decade)and WREQ(25.50 mm/decade),but a downward trend in EFFPRE(-11.8 mm/decade)over the second period.Changes in PET,EFFPRE and WREQ in winter have the impact on the annual trend.Among climate variables,WREQ showed a significant correlation(r=0.59)with minimum temperature.The increase in WREQ and decrease in EFFPRE would exacerbate the agricultural water crisis in Iran.With all changes in PET and WREQ,immediate actions are needed to address the challenges in agriculture and adapt to the changing climate.展开更多
Windbreak and sand fixation services(SR)provided by grasslands are a joint result of climate change and human activities.Series of grassland protection measurements have been successively implemented on Inner Mongolia...Windbreak and sand fixation services(SR)provided by grasslands are a joint result of climate change and human activities.Series of grassland protection measurements have been successively implemented on Inner Mongolia grasslands since 2000,but their effects on SR remains unclear.Based on satellite-derived vegetation dynamics and the Revised Wind Erosion Equation(RWEQ)model,this paper developed a method for quantitatively separating the impact of human activities on SR and revealed the contribution of human activities to SR in the Inner Mongolia grasslands from 2000 to 2020.In 2020,the actual sand fixation(SRA)of Inner Mongolia grasslands was 12.50 t·ha^(-1),spatially characterized as lower in the eastern and western parts,which was dominated by the sparse vegetation coverage and the low potential wind erosion respectively,while higher in the central part,due to the grassland vulnerability.The human-driven sand fixation(SRH)of Inner Mongolia grasslands changed from–1.28 t·ha^(-1)to–0.14 t·ha^(-1)from 2000 to 2020,indicating human activities inhibited SR,but the inhibition was gradually weakened.In semidesert and meadow steppes,the SRHchanged from–3.00 t·ha^(-1)to 0.00 t·ha^(-1)and–0.16 t·ha^(-1)to 0.00 t·ha^(-1),respectively,which showed that the effect of human activities changed from inhibition to promotion.However,it should be noted that human activities still inhibited the SR in typical steppes.The results implicated that grassland ecological protection should pay much more attention to reasonable use of vulnerable typical steppes.Future grassland use requires quantitative evaluation on the effects of human activity for precise monitoring and sustainable management.展开更多
[ Objective] To discuss regional response of reference evapotranspiration （ ETo ） to global climate change and its influencing factors. [Method] Penman-Monteith equation was adopted to calculate ET0 in Australia fro...[ Objective] To discuss regional response of reference evapotranspiration （ ETo ） to global climate change and its influencing factors. [Method] Penman-Monteith equation was adopted to calculate ET0 in Australia from 1998 to 2007. Spatiotemporal change characteristics were analyzed by using GIS spatial analysis tools and relationships between ETo and main climate factors were also analyzed. [ Resultsl The results showed that multi-year average ET0 increased from the east and south part to the northwest part and inland, and its distribution was consistent with climate zones. Multi-year average ETo of the whole region was 1 750 mm, obtaining minimum and maximum values in 2000 and 2002 respectively. Regional ETo decreased in the order of summer, spring, autumn and winter; January and December got the highest monthly ET0, while June got the lowest value 79.55 mm. ETo positively correlated with mean temperature and solar radiation, R2 for each were 0.83 and 0.94, while the relationship between ETo and average relative humidity was negative, and precipitation had no significant relationship with ET0. [ Conclusion] This research could provide important reference for crop water requirement study and making irrigation method for Australia.展开更多
Climate warming and humidification trends have significantly influenced vegetation growth patterns in Chinese semi-arid areas.Exploring vegetation dynamics is crucial for understanding regional ecosystem structure and...Climate warming and humidification trends have significantly influenced vegetation growth patterns in Chinese semi-arid areas.Exploring vegetation dynamics is crucial for understanding regional ecosystem structure and improving the efforts of ecosystem restoration.However,the applicability of various vegetation indices(VIs)in these arid areas remains uncertain.Evaluating the applicability of multiple VIs for vegetation monitoring can elucidate the variability of VIs performance at regional scale.Therefore,this study selected the Zuli River Basin(ZLRB),a typical loess hilly watershed in the semi-arid areas of China.Using Landsat data,we calculated the Normalized Difference Vegetation Index(NDVI),Enhanced Vegetation Index(EVI),and kernel NDVI(kNDVI)for the ZLRB from 1990 to 2020.We analyzed the spatiotemporal variations of these VIs using trend analysis and the Mann-Kendall test,and quantified the contributions of climate change(considering time-lag effects)and human activities to VIs changes through wavelet and residual analyses.Results indicated that VIs generally exhibited an upward trend in the ZLRB,with significant improvements observed in 54.91% of the area for NDVI,31.69% for EVI,and 33.71% for kNDVI.Among them,NDVI outperformed EVI and kNDVI in capturing vegetation changes in the semi-arid area.VIs responded to precipitation with 1-month time lag and no time lag to temperature during growing season.Moreover,precipitation had a stronger positive correlation with VIs than temperature.Climate change was identified as the dominant driver of vegetation dynamics in the ZLRB,accounting for 93.12% of NDVI variation,while human activities contributed only 6.88%.Comparative analysis of VIs suggests that NDVI was more suitable for describing vegetation changes in the typical arid area of the ZLRB.Our findings underscore the importance of selecting appropriate VIs for targeted ecological restoration and sustainable land management.展开更多
The ecological quality of inland areas is an important aspect of the United Nations Sustainable Development Goals(UN SDGs).The ecological environment of Northwest China is vulnerable to changes in climate and land use...The ecological quality of inland areas is an important aspect of the United Nations Sustainable Development Goals(UN SDGs).The ecological environment of Northwest China is vulnerable to changes in climate and land use/land cover,and the changes in ecological quality in this arid region over the last two decades are not well understood.This makes it more difficult to advance the UN SDGs and develop appropriate measures at the regional level.In this study,we used the Moderate Resolution Imaging Spectroradiometer(MODIS)products to generate remote sensing ecological index(RSEI)on the Google Earth Engine(GEE)platform to examine the relationship between ecological quality and environment in Xinjiang during the last two decades(from 2000 to 2020).We analyzed a 21-year time series of the trends and spatial characteristics of ecological quality.We further assessed the importance of different environmental factors affecting ecological quality through the random forest algorithm using data from statistical yearbooks and land use products.Our results show that the RSEI constructed using the GEE platform can accurately reflect the ecological quality information in Xinjiang because the contribution of the first principal component was higher than 90.00%.The ecological quality in Xinjiang has increased significantly over the last two decades,with the northern part of this region having a better ecological quality than the southern part.The areas with slightly improved ecological quality accounted for 31.26%of the total land area of Xinjiang,whereas only 3.55%of the land area was classified as having a slightly worsen(3.16%)or worsen(0.39%)ecological quality.The vast majority of the deterioration in ecological quality mainly occurred in the barren areas Temperature,precipitation,closed shrublands,grasslands and savannas were the top five environmental factors affecting the changes in RSEI.Environmental factors were allocated different weights for different RSEI categories.In general,the recovery of ecological quality in Xinjiang has been controlled by climate and land use/land cover during the last two decades and policy-driven ecological restoration is therefore crucial.Rapid monitoring of inland ecological quality using the GEE platform is projected to aid in the advancement of the comprehensive assessment of the UN SDGs.展开更多
The Qinghai-Tibet Plateau(QTP),also known as the Third Pole of the Earth,is a vital ecological security barrier for China.It is a tremendously sensitive region affected by the impacts of global climate change.The esca...The Qinghai-Tibet Plateau(QTP),also known as the Third Pole of the Earth,is a vital ecological security barrier for China.It is a tremendously sensitive region affected by the impacts of global climate change.The escalating intensity of climate change has presented profound challenges to its ecosystem functions and stability.This study first analyzes the spatiotemporal variations of the QTP ecosystem patterns and the key functions of the Plateau including water conservation,soil conservation,and windbreak and sand fixation from 2000 to 2020.It clarifies the regional differences in ecosystem functions and their importance,further evaluates the stability of ecosystem functions,and lays a scientific foundation for an ecological civilization on the Plateau by implementing conservation and restoration projects.The main results show that:(1)From 2000 to 2020,the wetland area in the QTP increased,while the grassland area significantly decreased.There were improvements in water conservation and windbreak and sand fixation capacities,with annual rates of change being 3.57m~3·ha^(-1)·a^(-1)and 0.23 t·ha^(-1)·a^(-1),respectively.However,the overall soil conservation trend declined during the same period,with an annual change rate of-0.16 t·ha^(-1)·a^(-1).(2)The core areas of water conservation,soil conservation,and windbreak and sand fixation on the QTP accounted for 12.7%,13.9%,and 14.2%of the total area,respectively.The core water conservation areas are mainly the southeastern QTP,Sanjiangyuan,and Naqu,while the core windbreak and sand fixation areas were concentrated in the central and western parts of the Plateau.The core soil conservation areas surrounded the entire interior of the Plateau.(3)From 2000 to 2020,the water conservation,soil conservation,and windbreak sand-fixation function on the QTP had higher stability in the southeastern and central parts,while stability was lower in the western region.Considering the stability assessment and ecological protection and restoration practices,the QTP can be divided into three major categories and 16 ecological functional zones.Differentiated ecological protection and restoration efforts can be implemented based on the different core ecosystem functions and zoning.展开更多
Using multi-mesh gillnets and trawls, the fish communities in Dianshan Lake at 6 stations from Oct. 2009 to Jul. 2010 were investigated seasonally to reveal the biodiversity and its spatial and temporal distribution p...Using multi-mesh gillnets and trawls, the fish communities in Dianshan Lake at 6 stations from Oct. 2009 to Jul. 2010 were investigated seasonally to reveal the biodiversity and its spatial and temporal distribution patterns. The long-term changes in their structural characteristics were then analyzed to identify the main infl uencing factors and several measures for lake restoration were put forward. Thirty six species, belonging to 9 family and 30 genera, were collected, amongst which, the order Cypriniformes accounted for 61.1% of the total species number. In terms of importance value, Cypriniformes was the predominant group, Coilia nasus the dominant species, while Cyprinus carpio and Rhinogobius giurinus were the subdominant taxa. The community types did not differ among stations, but between seasons. There were no significant differences between seasons and among stations in species diversity, but richness differed both spatially and seasonally. Along with the process of eutrophication and the drastic reduction of the area colonized by macrophytes from 1959 to 2009–2010, the fish diversity declined markedly, and species numbers of herbivores and piscivores declined proportionately more than those of invertivores, omnivores, and planktivores. The decline of potamophilus and river-lake migratory fish was more marked than those of sedentary, river-sea migratory, and estuarine fishes. Eutrophication concomitant with sharp reduction of macrophyte area and overfishing may be the main reasons for the decline in fish diversity in Dianshan Lake.展开更多
Glaciers are a reliable freshwater resource in arid regions of West China and the vulnerability of its changes is closely related to regional ecosystem services and economic sustainable development. Here, we took the ...Glaciers are a reliable freshwater resource in arid regions of West China and the vulnerability of its changes is closely related to regional ecosystem services and economic sustainable development. Here, we took the Qilian Mountains as an example and analyzed the spatiotemporal characteristics of glacier changes from 1998 to 2018, based on remote sensing images and the Second Chinese Glacier Inventory. We estimated the basic organizational framework and evaluation index system of glacier change vulnerability from exposure, sensitivity and adaptability, which covered the factors of physical geography, population status and socio-economic level. We analyzed the spatial and temporal evolutions of glacier change vulnerability by using the vulnerability evaluation model. Our results suggested that:(1) Glacier area and volume decreased by 71.12±98.98 km^(2) and 5.59±4.41 km^(3), respectively, over the recent two decades, which mainly occurred at the altitude below 4800 m, with an area shrinking rate of 2.5%. In addition, glaciers in the northern aspect(northwest, north and northeast) had the largest area reduction. Different counties exhibited remarkable discrepancies in glacier area reduction, Tianjuan and Minle presented the maximum and minimum decrease, respectively.(2) Glacier change vulnerability level showed a decreasing trend in space from the central to the northwestern and southeastern regions with remarkable differences. Vulnerability level had increased significantly over time and was mainly concentrated in moderate, high and extreme levels with typical characteristics of phases and regional complexity. Our study can not only help to understand and master the impacts of recent glacier changes on natural and social aspects but also be conducive to evaluate the influences of glacier retreat on socio-economic developments in the future, thus providing references for formulating relevant countermeasures to achieve regional sustainable development.展开更多
基金National Natural Science Foundation of China,No.42371103Natural Science Basic Research Plan in Shaanxi Province of China,No.2023-JC-YB-229。
文摘Understanding the local ecological security status and its underlying drivers can be used as an effective reference for balancing ecosystem development with societal needs. This study assesses the ecological security of the Loess Plateau(LP) by integrating ecosystem health and ecosystem services, explores the varying impacts of ecosystem structure, quality, and services on ecological security index(ESI), and identifies the key driving factors of ESI using the Geodetector model. The results show that:(1) the average ESI indicates a relatively safe ecological status in LP with a significant increase in ESI observed in 50.21% of the region, largely due to the ecological restoration programs.(2) Natural factors predominantly influence ESI, although human factors play a significant role in the earthy-rocky mountain region and plateau wind-sand region.(3) The interactions between driving factors have a much greater impact on ESI than any single factor, with the interactions between precipitation and human factors being the most influential combination. This study provides a novel perspective on assessing ecological security in LP. We recommend that future ecological restoration efforts should consider the varying roles of ecosystem structure, quality, and services in ESI while tailoring strategies to the primary driving factors based on local conditions.
基金the National Key R&D Program(Grant No.2019YFE0115200)Natural Science Foundation of China(Grants No.42071217).
文摘The surface solar radiation in most parts of the world has undergone a phenomenon known as global dimming and brightening,characterized by an initial decrease followed by an increase.As a result,the sunshine duration(SD)has decreased in the past 60 years.Against the backdrop of global dimming and brightening,SD has decreased to varying degrees in many regions of China.Using the observed data of SD,cloud amount(total cloud amount and low cloud amount,abbreviated as TCA and LCA),precipitation,and relative humidity(RH)from 34 meteorological stations in Chongqing during the period of 1961-2020,along with a digital elevation model(DEM)with a resolution of 90 m,this study analyzed the spatiotemporal variations and influencing factors of SD.The analysis employed methods such as linear regression,Mann-Kendall test,wavelet transformation,and DEM-based possible SD distributed model.The results showed that the annual SD in Chongqing has significantly decreased over the last 60 years,with a decreasing interannual trend rate(ITR)of 40.4 h/10a.Except for no obvious trend in spring,SD decreased significantly in summer,autumn and winter at the ITR of 21.1 h/10a,8.5 h/10a and 7.5 h/10a,respectively.An abrupt decrease in the annual SD was found in 1979.The difference before and after the abrupt decrease was 177.7 h.The difference before and after the abrupt decrease was 177.7 h.The annual SD possessed the oscillation period of 11a.The spatial heterogeneity of the mean annual SD during the last 60 years was obvious.The distribution of SD in Chongqing is high in the northeast and low in the southeast.In addition,about 73%of the total area in Chongqing showed a significant and very significant decreasing trend.The regions with significant changes are mainly concentrated in the regions with altitudes of 200~1000 m.The increasing LCA was the main cause of the decrease of the annual SD in the regions with 200-400 m altitude decreased the most and changed the most.Increasing LCA is the primary cause of the reduction in annual SD,showing a strong negative correlation coefficient of-0.7292.In Chongqing,PM2.5 concentration showed a significant decrease trend in annual,spring,autumn and winter during 2000-2020,but the significant correlation between PM2.5 concentration and SD was only in autumn and reached an extremely significant level.
基金The National Research Program of China under contract No.2017YFC1405300.
文摘The long-term spatiotemporal changes of surface biogenic elements in the Changjiang River Estuary and adjacent waters during the summer of 2008–2016 were analyzed in this study.The concentrations of dissolved inorganic nitrogen(DIN),soluble reactive phosphate(PO_(4)^(3−))and silicate(SiO_(3)^(2−))were generally stable,with a slight decrease of DIN and PO_(4)^(3−),and a slight increase of SiO_(3)^(2−),which mainly occurred in the estuarine waters.The grey correlation analysis was carried out between biogenic elements and chlorophyll a(Chl-a).Results showed that compared with the absolute values of biogenic elements,the correlations between the concentration ratio of nitrogen to phosphorus(N/P),ratio of silicon to nitrogen(Si/N)and Chl-a were closer,indicating the important influence on phytoplankton by the structure of biogenic elements.The study area was generally in a state of potential P limitation,and could have potential impact on the phytoplankton community,triggering the shift of red tide dominant species from diatoms to dinoflagellates.
基金Major Project of High-resolution Earth Observation System
文摘The Three-River Headwaters Region （TRHR）, which is the source area of the Yangtze River, Yellow River, and Lancang River, is of key importance to the ecological secu- rity of China. Because of climate changes and human activities, ecological degradation oc- curred in this region. Therefore, ＂The nature reserve of Three-River Sou,＇ce Regions＂ was established, and ＂The project of ecological protection and construction for the Three-River Headwaters Nature Reserve＂ was implemented by the Chinese government. This study, based on MODIS-NDVI and climate data, aims to analyze the spatiotemporal changes in vegetation coverage and its driving factors in the TRHR between 2000 and 2011, from three dimensions. Linear regression, Hurst index analysis, and partial correlation analysis were employed. The results showed the following： （1） In the past 12 years （2000-2011）, the NDVI of the study area increased, with a linear tendency being 1.2%/10a, of which the Yangtze and Yellow River source regions presented an increasing trend, while the Lancang River source region showed a decreasing trend. （2） Vegetation coverage presented an obvious spatial difference in the TRHR, and the NDVI frequency was featured by a bimodal structure. （3） The area with improved vegetation coverage was larger than the degraded area, being 64.06% and 35.94%, respectively during the study period, and presented an increasing trend in the north and a decreasing trend in the south. （4） The reverse characteristics of vegetation cov- erage change are significant. In the future, degradation trends will be mainly found in the Yangtze River Basin and to the north of the Yellow River, while areas with improving trends are mainly distributed in the Lancang River Basin. （5） The response of vegetation coverage to precipitation and potential evapotranspiration has a time lag, while there is no such lag in the case of temperature. （6） The increased vegetation coverage is mainly attributed to the warm-wet climate change and the implementation of the ecological protection project.
基金National Natural Science Foundation of China,No.41861040, No.41761047, No.41961027。
文摘Sensitivity assessment is useful for monitoring land desertification. Research into how to prevent and control desertification is also important. In the arid region of northwest China, desertification is becoming worse and is a serious problem that affects local sustainable development. Based on remote-sensing and geographic information system technology, this study establishes a 'soil-terrain-hydrology-climate-vegetation' desertification sensitivity comprehensive evaluation system to reflect the spatiotemporal changes of land desertification, and proposes a spatial distance model to calculate a desertification sensitivity index. The spatiotemporal change characteristics of land desertification sensitivity in northwest China are quantitatively assessed from 2000 to 2017. Moreover, the main driving factors are analyzed using the geographical detector method. The results show the following.(1) Terrain, soil, climate, vegetation and hydrology affect and restrict each other, and constitute the background conditions of the distributions and changes of sensitivity to desertification in northwest China.(2) Desertification sensitivity generally displays a low distribution characteristic on the periphery of the area and a high one in the interior. The low-sensitivity regions are mainly in the five major mountain ranges(Altai Mountains, Tianshan Mountains, Kunlun Mountains, Altun Mountains and Qilian Mountains), while the high-sensitivity regions are mainly in regions such as the Junggar Basin, the Tarim Basin and the Inner Mongolia Plateau, as well as the Taklimakan Desert, Badain Jaran Desert and Tengger Desert. The spatial distribution of desertification sensitivity is obviously regional, and the high-and low-sensitivity regions have clear boundaries and a concentrated distribution.(3) With regard to spatiotemporal evolution, changes in desertification sensitivity since 2000 have been predominantly stable, and the overall sensitivity has displayed a slowly decreasing trend, indicating that potential desertification regions are decreasing annually and that some achievements have been made in the control of regional desertification.(4) Soil and climate play a direct role in the driving factors of desertification in northwest China, and these have been found to be the most important influential factors. Vegetation is the most active and basic factor in changing the sensitivity. In addition, topography and hydrology play a role in restricting desertification changes. Socio-economic factors are the most rapid factors affecting regional desertification sensitivity, and their impacts tend to be gradually increasing. In general, desertification has been effectively controlled in northwest China, and positive results have been achieved in such control. However, against the backdrop of intensified global climate change, increasingly prominent human activities and new normals of socio-economic development, the monitoring, assessment and control of desertification in China still have a long way to go.
基金funded by the National Natural Science Foundation of China(42371219)the Key Natural Science Foundation of Gansu Province(24JRRA135)the Oasis Scientific Research Achievements Breakthrough Action Plan Project of Northwest Normal University(NWNU-LZKX-202302).
文摘Due to irrational human activities and extreme climate,the Qinghai-Xizang Plateau,China,faces a serious threat of desertification.Desertification has a detrimental effect on the ecological environment and socioeconomic development.In this study,the desertification sensitivity index(DSI)model was established by integrating the spatial distance model and environmentally sensitive area index evaluation method,and then the model was used to quantitatively analyze the spatial and temporal characteristics of desertification sensitivity of the Qinghai-Xizang Plateau from 1990 to 2020.The results revealed that:(1)a general increasing tendency from southeast to northwest was identified in the spatial distribution of desertification sensitivity.The low-sensitivity areas were mostly concentrated in the Hengduan and Nyaingqêntanglha mountains and surrounding forest and meadow areas.The high-sensitivity areas were located mainly in the Kunlun and Altun mountains and surrounding decertified areas.The center of gravity of all types of desertification-sensitive areas moved to the northwest,and the desertification sensitivity showed a decreasing trend as a whole;(2)the area of highly sensitive desertification areas decreased by 8.37%,with extreme sensitivity being the largest change among the sensitivity types.The desertification sensitivity transfer was characterized by a greater shift to lower sensitivity levels(24.56%)than to higher levels(2.03%),which demonstrated a declining trend;(3)since 1990,the change in desertification sensitivity has been dominated by the stabilizing type Ⅰ(29.30%),with the area of continuously increasing desertification sensitivity accounting for only 1.10%,indicating that the management of desertification has achieved positive results in recent years;and(4)natural factors have had a more significant impact on desertification sensitivity on the Xizang Plateau,whereas socioeconomic factors affected only localized areas.The main factors influencing desertification sensitivity were vegetation drought tolerance and aridity index.Studying spatiotemporal variations in desertification sensitivity and its influencing factors can provide a scientific foundation for developing strategies to control desertification on the Qinghai-Xizang Plateau.Dividing different desertification-sensitive areas on the basis of these patterns of change can facilitate the formulation of more targeted management and protection measures,contributing to ecological construction and sustainable economic development in the area.
基金funded by FCT (Funda??o para a Ciência e Tecnologia/Portuguese Foundation for Science and Technology),through the projects “Be Safe Slide-Landslide early warning soft technology prototype to improve community resilience and adaptation to environmental change”(PTDC/GES-AMB/30052/2017)“MIT-RSC-Multi-risk interactions towards resilient and sustainable cities”(MIT-EXPL/CS/0018/2019)+3 种基金Jorge Rocha was financed through FCT,within the framework of the project “TRIAD-Health risk and social vulnerability to arboviral diseases in mainland Portugal”(PTDC/GES-OUT/30210/2017)partially developed within the framework of the RISKCOAST project (Ref:SOE3/P4/E0868) funded by the Interreg SUDOE Program (3rd Call for proposals)Pedro Pinto Santos was fi nanced by FCT,within the framework of the contract CEEIND/00268/2017by the Research Unit UID/GEO/00295/2020
文摘Social vulnerability,as one of the risk components,partially explains the magnitude of the impacts observed after a disaster.In this study,a spatiotemporally comparable assessment of social vulnerability and its drivers was conducted in Portugal,at the civil parish level,for three census frames.The first challenging step consisted of the selection of meaningful and consistent variables over time.Data were normalized using the Adjusted Mazziotta-Pareto Index(AMPI)to obtain comparable adimensional-normalized values.A joint principal component analysis(PCA)was applied,resulting in a robust set of variables,interpretable from the point of view of their self-grouping around vulnerability drivers.A separate PCA for each census was also conducted,which proved to be useful in analyzing changes in the composition and type of drivers,although only the joint PCA allows the monitoring of spatiotemporal changes in social vulnerability scores and drivers from 1991 to 2011.A general improvement in social vulnerability was observed for Portugal.The two main drivers are the economic condition(PC1),and aging and depopulation(PC2).The remaining drivers highlighted are uprooting and internal mobility,and daily commuting.Census data proved their value in the territorial,social,and demographic characterization of the country,to support medium-and long-term disaster risk reduction measures.
基金supported by the National Natural Science Foundation of China (32271737, 32071544)the Interdisciplinary Innovation Team of the Chinese Academy of Sciences (CAS) “Light of West China” Program (xbzg-zdsys-202207)China Postdoctoral Science Foundation (2024M753155)。
文摘Mountain amphibians are exposed to a multitude of threats from climate change and anthropogenic disturbances. However, a lack of data hinders the understanding of the responses of mountain amphibians to these threats, which is becoming a conservation concern. Using frogs in the Hengduan Mountains, a biodiversity hotspot in Southwest China as indicators, we attempted to assess the extent and magnitude of changes in alpha diversity(species richness) and beta diversity(community turnover) between two periods(1930–2005 and 2006–2022). We compared elevational patterns for total, endemic and non-endemic frogs between the two periods, evaluated community turnover(i.e., S?rensen and Jaccard binary dissimilarity), and further quantified whether significant homogenization or differentiation of the frog communities occurred over time. Our results showed that the present species richness is greater than the historical species richness. The elevational patterns of total, endemic and non-endemic frogs were similar with slight changes across the two periods and clear increases in richness occurring at low and middle elevations. Although there was no significant biotic homogenization or differentiation over time, the community composition shifted dramatically. This study highlights the importance of assessing spatiotemporal changes in biodiversity in response to environmental changes and contributes to mountain species conservation as global change intensifies. We therefore call for greater efforts in community resurveys to assess biodiversity changes and provide useful insights for conservation strategies and action implementation.
基金The National Key R&D Program of China,No.2023YFD2000105The Shaanxi Province Science and Technology Innovation Team,No.2021TD-51The Shaanxi Province Geoscience Big Data and Geohazard Prevention Innovation Team(2022)。
文摘Shaanxi province in China is rich in vegetation resources,making the study of vegetation phenology crucial for understanding climate change and ecological dynamics.Previous studies on Shaanxi have primarily focused on coarse-scale phenology,which results in the loss of essential spatial details due to the lack of finer-scale analyses.Moreover,the impact of rapid urbanisation on the phenology of various vegetation types in this region remains unclear.To address these gaps,we integrated Landsat and MODIS data to generate a daily 30 m NDVI sequence.Vegetation phenology across Shaanxi from 2000 to 2020 was then extracted and analysed,and the responses of different vegetation types to urbanisation were explored.Results indicated that accurate vegetation phenology can be obtained at a 30 m resolution,which is more precise than conventional coarse-scale investigations.The Start of Season(SOS)and End of Season(EOS)in the province advanced by-0.56 and-0.08 day/year,respectively,from 2000 to 2020.In general,the SOS gradually delays,and the EOS progressively advances with increasing latitude.However,anomalies were identified in regions south of 32.64°N and across the zone from 34.04°N to 37.56°N,which are primarily due to the effects of high elevation and rapid urbanisation,respectively.Further investigation into phenological differences among various vegetation types revealed that forests exhibit the earliest SOS,while grasslands present the latest.In addition,a significant negative correlation was found between the SOS difference and air temperature difference along the urban-rural gradient,with urbanisation having the most significant impact on cropland phenology.This study provides valuable insights into vegetation phenology and its response to urbanisation.These insights offer crucial information for ecological conservation and management strategies.
基金supported as a special project by the Agriculture Ministry of China(Grant No.201503119)the Natural Science Foundation of China(Grant No.41471232)
文摘The dynamics of soil organic carbon(SOC)in cropland is one of the central issues related to both soil fertility and environmental safety. However, little information is available at county level regarding the spatiotemporal variability of SOC in the southwestern mountainous region of China. Thus, this study aimed to explore spatiotemporal changes of SOC in the cultivated soil layer of dry land in Mojiang County,Yunnan Province, China. Data were obtained from the second national soil survey(SNSS) of 1985 and soil tests for fertilizer application carried out by the Mojiang Agricultural Bureau in 2006. The ANOVA test was applied to determine any significant differences between the datasets, while semivariogram analysis was performed on geostatistics via an ordinary Kriging method in order to map spatial patterns of soil organic carbon density(SOCD). The results revealed that SOCD in the cultivated soil layer significantly decreased from 3.93 kg m^(-2) in 1985 to 2.89 kg m^(-2) in 2006, with a total soil organic carbon stock(SOCS) decrease of 41.54×10~4 t over the same period. SOCS levels fell most markedly in yellow-brown soil at a rate of51.52%, while an increase of 8.70% was found in the analysed latosol. Geostatistical analysis also showed that the recorded changes in SOCD between 1985 and2006 were spatially structured. The decreasing trend might be attributed to the combined action of intense cultivation, major crop residue removal without any protective tillage measures, unreasonable fertilization and natural climatic diversity inducing a large decrease in SOC in the studied cultivated dry land region of Mojiang County. Therefore, management measures such as protective tillage should be undertaken in order to enhance soil C sequestration.
基金jointly supported by the National Natural Science Foundation of China(41671093)the National Key R&D Program of China(2017YFA0604701,2012CB955304)
文摘Since the Grain for Green(GFG)program was implemented in 1999,most steeply sloping farmlands in the Loess Plateau of China have been returned to forestland and grassland.To understand its impact on the food production,this study analyzed the spatiotemporal changes of food crop production(FCP)in the plateau and quantified the contribution of sown area and yield changes to the total FCP during 1998–2014 using factor decomposition models,and then discussed the impact of GFG program on the FCP based on literature data.With the implementation of GFG program,total sown area in the Loess Plateau quickly deceased by 17.3%from 1998 to 2003,and then gradually restored to 1.03×107 hm2 in 2010.Thereafter,it slightly decreased to 1.02×107 hm2(94.6%of the area in 1998)in 2014.By contrast,total FCP generally showed an apparent growth trend,averagely increased by 1.71%per year in the whole plateau during 1998–2014.This increase was jointly contributed by the improved yield of individual crops,and the adjustment of cropping structure,i.e.,the expansion of high yield maize crop.The factor decomposition analysis results indicate that the sown area shrinkage only reduced the growth rate of total FCP by 0.29%per year during 1998–2014,although a significant impact was found for the early stage of 1999–2003.The results suggest that the implementation of GFG program would not induce an obvious risk of the food security.Therefore,it is suggested that the GFG program should be set as a long-term strategic policy,by not only supporting the conversion of slope farmlands,but also helping local farmers to seek sustainable ways of land use to improve the income and livelihood.It can be combined with the poverty eradication program,to simultaneously achieve the national goals of ecological civilization building and the livelihood improvement of rural people in the Loess Plateau.Considering rainfall limitation,the conversion of slope farmlands should be prioritized to grasslands.
基金Guangxi Natural Science Foundation,No.2020GXNSFAA297176National Natural Science Foundation of China,No.U21A2022,No.42101369Youth Teacher Scientific Research Ability Improvement Project of Guangxi,No.2021KY0393。
文摘Accurate and rapid evaluation of the regional eco-environment is critical to policy formulation.The remote sensing ecological index(RSEI)model of the Guangxi Beibu Gulf Economic Zone(GBGEZ)during 2001-2020 was established and evaluated using four indices:dryness,wetness,greenness,and heat.This paper proposes an information granulation method for remote sensing based on the RSEI index value that uses granular computing.We found that:(1)From 2001 to 2020,the eco-environmental quality(EEQ)of GBGEZ tended to improve,and the spatial difference tended to expand.The regional spatial distribution of the eco-environment is primarily in the second-level and third-level areas,and the EEQ in the east and west is better than that in the middle.The contribution of greenness,wetness,and dryness to the improvement of EEQ in the study region increased year by year.(2)From 2001to 2020,the order of the contribution of the EEQ index in the GBGEZ was dryness,wetness,greenness,and heat.(3)The social and economic activities in the study region had a certain inhibitory effect on the improvement of the EEQ.
文摘Agriculture needs to produce more food to feed the growing population in the 21st century.It makes the reference crop water requirement(WREQ)a major challenge especially in regions with limited water and high water demand.Iran,with large climatic variability,is experiencing a serious water crisis due to limited water resources and inefficient agriculture.In order to overcome the issue of uneven distribution of weather stations,gridded Climatic Research Unit(CRU)data was applied to analyze the changes in potential evapotranspiration(PET),effective precipitation(EFFPRE)and WREQ.Validation of data using in situ observation showed an acceptable performance of CRU in Iran.Changes in PET,EFFPRE and WREQ were analyzed in two 30-a periods 1957-1986 and 1987-2016.Comparing two periods showed an increase in PET and WREQ in regions extended from the southwest to northeast and a decrease in the southeast,more significant in summer and spring.However,EFFPRE decreased in the southeast,northeast,and northwest,especially in winter and spring.Analysis of annual trends revealed an upward trend in PET(14.32 mm/decade)and WREQ(25.50 mm/decade),but a downward trend in EFFPRE(-11.8 mm/decade)over the second period.Changes in PET,EFFPRE and WREQ in winter have the impact on the annual trend.Among climate variables,WREQ showed a significant correlation(r=0.59)with minimum temperature.The increase in WREQ and decrease in EFFPRE would exacerbate the agricultural water crisis in Iran.With all changes in PET and WREQ,immediate actions are needed to address the challenges in agriculture and adapt to the changing climate.
基金National Key Research and Development Program of China,No.2022YFF1301802The Second TibetaPlateau Scientific Expedition and Research Program,No.2019QZKK1006。
文摘Windbreak and sand fixation services(SR)provided by grasslands are a joint result of climate change and human activities.Series of grassland protection measurements have been successively implemented on Inner Mongolia grasslands since 2000,but their effects on SR remains unclear.Based on satellite-derived vegetation dynamics and the Revised Wind Erosion Equation(RWEQ)model,this paper developed a method for quantitatively separating the impact of human activities on SR and revealed the contribution of human activities to SR in the Inner Mongolia grasslands from 2000 to 2020.In 2020,the actual sand fixation(SRA)of Inner Mongolia grasslands was 12.50 t·ha^(-1),spatially characterized as lower in the eastern and western parts,which was dominated by the sparse vegetation coverage and the low potential wind erosion respectively,while higher in the central part,due to the grassland vulnerability.The human-driven sand fixation(SRH)of Inner Mongolia grasslands changed from–1.28 t·ha^(-1)to–0.14 t·ha^(-1)from 2000 to 2020,indicating human activities inhibited SR,but the inhibition was gradually weakened.In semidesert and meadow steppes,the SRHchanged from–3.00 t·ha^(-1)to 0.00 t·ha^(-1)and–0.16 t·ha^(-1)to 0.00 t·ha^(-1),respectively,which showed that the effect of human activities changed from inhibition to promotion.However,it should be noted that human activities still inhibited the SR in typical steppes.The results implicated that grassland ecological protection should pay much more attention to reasonable use of vulnerable typical steppes.Future grassland use requires quantitative evaluation on the effects of human activity for precise monitoring and sustainable management.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences(No.KZCX-XY-340)the Frontier Field Program of NEIGAE-CAS (No.C08Y46)~~
文摘[ Objective] To discuss regional response of reference evapotranspiration （ ETo ） to global climate change and its influencing factors. [Method] Penman-Monteith equation was adopted to calculate ET0 in Australia from 1998 to 2007. Spatiotemporal change characteristics were analyzed by using GIS spatial analysis tools and relationships between ETo and main climate factors were also analyzed. [ Resultsl The results showed that multi-year average ET0 increased from the east and south part to the northwest part and inland, and its distribution was consistent with climate zones. Multi-year average ETo of the whole region was 1 750 mm, obtaining minimum and maximum values in 2000 and 2002 respectively. Regional ETo decreased in the order of summer, spring, autumn and winter; January and December got the highest monthly ET0, while June got the lowest value 79.55 mm. ETo positively correlated with mean temperature and solar radiation, R2 for each were 0.83 and 0.94, while the relationship between ETo and average relative humidity was negative, and precipitation had no significant relationship with ET0. [ Conclusion] This research could provide important reference for crop water requirement study and making irrigation method for Australia.
基金funded by the National Natural Science Foundation of China(U21A2011).
文摘Climate warming and humidification trends have significantly influenced vegetation growth patterns in Chinese semi-arid areas.Exploring vegetation dynamics is crucial for understanding regional ecosystem structure and improving the efforts of ecosystem restoration.However,the applicability of various vegetation indices(VIs)in these arid areas remains uncertain.Evaluating the applicability of multiple VIs for vegetation monitoring can elucidate the variability of VIs performance at regional scale.Therefore,this study selected the Zuli River Basin(ZLRB),a typical loess hilly watershed in the semi-arid areas of China.Using Landsat data,we calculated the Normalized Difference Vegetation Index(NDVI),Enhanced Vegetation Index(EVI),and kernel NDVI(kNDVI)for the ZLRB from 1990 to 2020.We analyzed the spatiotemporal variations of these VIs using trend analysis and the Mann-Kendall test,and quantified the contributions of climate change(considering time-lag effects)and human activities to VIs changes through wavelet and residual analyses.Results indicated that VIs generally exhibited an upward trend in the ZLRB,with significant improvements observed in 54.91% of the area for NDVI,31.69% for EVI,and 33.71% for kNDVI.Among them,NDVI outperformed EVI and kNDVI in capturing vegetation changes in the semi-arid area.VIs responded to precipitation with 1-month time lag and no time lag to temperature during growing season.Moreover,precipitation had a stronger positive correlation with VIs than temperature.Climate change was identified as the dominant driver of vegetation dynamics in the ZLRB,accounting for 93.12% of NDVI variation,while human activities contributed only 6.88%.Comparative analysis of VIs suggests that NDVI was more suitable for describing vegetation changes in the typical arid area of the ZLRB.Our findings underscore the importance of selecting appropriate VIs for targeted ecological restoration and sustainable land management.
基金the Key Laboratory Open Subjects of Xinjiang Uygur Autonomous Region Science and Technology Department(2020D04038)the Key Project of Natural Science Foundation of Xinjiang Uygur Autonomous Region(2021D01D06)the National Natural Science Foundation of China(41961059).
文摘The ecological quality of inland areas is an important aspect of the United Nations Sustainable Development Goals(UN SDGs).The ecological environment of Northwest China is vulnerable to changes in climate and land use/land cover,and the changes in ecological quality in this arid region over the last two decades are not well understood.This makes it more difficult to advance the UN SDGs and develop appropriate measures at the regional level.In this study,we used the Moderate Resolution Imaging Spectroradiometer(MODIS)products to generate remote sensing ecological index(RSEI)on the Google Earth Engine(GEE)platform to examine the relationship between ecological quality and environment in Xinjiang during the last two decades(from 2000 to 2020).We analyzed a 21-year time series of the trends and spatial characteristics of ecological quality.We further assessed the importance of different environmental factors affecting ecological quality through the random forest algorithm using data from statistical yearbooks and land use products.Our results show that the RSEI constructed using the GEE platform can accurately reflect the ecological quality information in Xinjiang because the contribution of the first principal component was higher than 90.00%.The ecological quality in Xinjiang has increased significantly over the last two decades,with the northern part of this region having a better ecological quality than the southern part.The areas with slightly improved ecological quality accounted for 31.26%of the total land area of Xinjiang,whereas only 3.55%of the land area was classified as having a slightly worsen(3.16%)or worsen(0.39%)ecological quality.The vast majority of the deterioration in ecological quality mainly occurred in the barren areas Temperature,precipitation,closed shrublands,grasslands and savannas were the top five environmental factors affecting the changes in RSEI.Environmental factors were allocated different weights for different RSEI categories.In general,the recovery of ecological quality in Xinjiang has been controlled by climate and land use/land cover during the last two decades and policy-driven ecological restoration is therefore crucial.Rapid monitoring of inland ecological quality using the GEE platform is projected to aid in the advancement of the comprehensive assessment of the UN SDGs.
基金The Second Tibetan Plateau Scientific Expedition and Research Program,No.2019QZKK0404。
文摘The Qinghai-Tibet Plateau(QTP),also known as the Third Pole of the Earth,is a vital ecological security barrier for China.It is a tremendously sensitive region affected by the impacts of global climate change.The escalating intensity of climate change has presented profound challenges to its ecosystem functions and stability.This study first analyzes the spatiotemporal variations of the QTP ecosystem patterns and the key functions of the Plateau including water conservation,soil conservation,and windbreak and sand fixation from 2000 to 2020.It clarifies the regional differences in ecosystem functions and their importance,further evaluates the stability of ecosystem functions,and lays a scientific foundation for an ecological civilization on the Plateau by implementing conservation and restoration projects.The main results show that:(1)From 2000 to 2020,the wetland area in the QTP increased,while the grassland area significantly decreased.There were improvements in water conservation and windbreak and sand fixation capacities,with annual rates of change being 3.57m~3·ha^(-1)·a^(-1)and 0.23 t·ha^(-1)·a^(-1),respectively.However,the overall soil conservation trend declined during the same period,with an annual change rate of-0.16 t·ha^(-1)·a^(-1).(2)The core areas of water conservation,soil conservation,and windbreak and sand fixation on the QTP accounted for 12.7%,13.9%,and 14.2%of the total area,respectively.The core water conservation areas are mainly the southeastern QTP,Sanjiangyuan,and Naqu,while the core windbreak and sand fixation areas were concentrated in the central and western parts of the Plateau.The core soil conservation areas surrounded the entire interior of the Plateau.(3)From 2000 to 2020,the water conservation,soil conservation,and windbreak sand-fixation function on the QTP had higher stability in the southeastern and central parts,while stability was lower in the western region.Considering the stability assessment and ecological protection and restoration practices,the QTP can be divided into three major categories and 16 ecological functional zones.Differentiated ecological protection and restoration efforts can be implemented based on the different core ecosystem functions and zoning.
基金Supported by the Science and Technology Commission of Shanghai Municipality(Nos.08DZ1203101,08DZ1203102)the Shanghai University Knowledge Service Platform,Shanghai Ocean University Aquatic Animal Breeding Center(No.ZF1206)the Open Project of Key Laboratory of Freshwater Biodiversity Conservation and Utilization,Certificated by Ministry of Agriculture of China
文摘Using multi-mesh gillnets and trawls, the fish communities in Dianshan Lake at 6 stations from Oct. 2009 to Jul. 2010 were investigated seasonally to reveal the biodiversity and its spatial and temporal distribution patterns. The long-term changes in their structural characteristics were then analyzed to identify the main infl uencing factors and several measures for lake restoration were put forward. Thirty six species, belonging to 9 family and 30 genera, were collected, amongst which, the order Cypriniformes accounted for 61.1% of the total species number. In terms of importance value, Cypriniformes was the predominant group, Coilia nasus the dominant species, while Cyprinus carpio and Rhinogobius giurinus were the subdominant taxa. The community types did not differ among stations, but between seasons. There were no significant differences between seasons and among stations in species diversity, but richness differed both spatially and seasonally. Along with the process of eutrophication and the drastic reduction of the area colonized by macrophytes from 1959 to 2009–2010, the fish diversity declined markedly, and species numbers of herbivores and piscivores declined proportionately more than those of invertivores, omnivores, and planktivores. The decline of potamophilus and river-lake migratory fish was more marked than those of sedentary, river-sea migratory, and estuarine fishes. Eutrophication concomitant with sharp reduction of macrophyte area and overfishing may be the main reasons for the decline in fish diversity in Dianshan Lake.
基金Second Tibetan Plateau Scientific Expedition and Research Program,No.2019QZKK0201Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDA20020102,No.XDA20060201+2 种基金State Key Laboratory of Cryospheric Science,No.SKLCS-ZZ-2021National Natural Science Foundation of China,No.41721091,42001067National Cryosphere Desert Data Center,No.20D03。
文摘Glaciers are a reliable freshwater resource in arid regions of West China and the vulnerability of its changes is closely related to regional ecosystem services and economic sustainable development. Here, we took the Qilian Mountains as an example and analyzed the spatiotemporal characteristics of glacier changes from 1998 to 2018, based on remote sensing images and the Second Chinese Glacier Inventory. We estimated the basic organizational framework and evaluation index system of glacier change vulnerability from exposure, sensitivity and adaptability, which covered the factors of physical geography, population status and socio-economic level. We analyzed the spatial and temporal evolutions of glacier change vulnerability by using the vulnerability evaluation model. Our results suggested that:(1) Glacier area and volume decreased by 71.12±98.98 km^(2) and 5.59±4.41 km^(3), respectively, over the recent two decades, which mainly occurred at the altitude below 4800 m, with an area shrinking rate of 2.5%. In addition, glaciers in the northern aspect(northwest, north and northeast) had the largest area reduction. Different counties exhibited remarkable discrepancies in glacier area reduction, Tianjuan and Minle presented the maximum and minimum decrease, respectively.(2) Glacier change vulnerability level showed a decreasing trend in space from the central to the northwestern and southeastern regions with remarkable differences. Vulnerability level had increased significantly over time and was mainly concentrated in moderate, high and extreme levels with typical characteristics of phases and regional complexity. Our study can not only help to understand and master the impacts of recent glacier changes on natural and social aspects but also be conducive to evaluate the influences of glacier retreat on socio-economic developments in the future, thus providing references for formulating relevant countermeasures to achieve regional sustainable development.
