Ecosystem services are a key to human survival and global sustainability. Consequently, there is the need to avoid unscrupulous or unplanned land use practices that can compromise these services in addition to the ong...Ecosystem services are a key to human survival and global sustainability. Consequently, there is the need to avoid unscrupulous or unplanned land use practices that can compromise these services in addition to the ongoing changes in the global climate whose potentially negative impact are yet to be fully comprehended thus far. The primary objective of this study was to evaluate the Land use—land cover changes of some Eastern Shore sub-watersheds of Maryland from 1986-2006 and qualitatively assess the impact of the changes on some key ecosystem services. Landsat-TM data for Maryland Eastern Shore in the United States were analyzed in ENVI and ArcGIS environment and data interpreted qualitatively. The result showed that forest lands increased during the study period and thus enhanced carbon sequestration favorable for mitigating global warming in the area. Also, the extent of surface water cover increased slightly, possibly due to rising sea level and a thus a potential threat to biodiversity and barrier islands nearby. There was also a significant increase in urban lands due to population increase and thus increase in the extent of impervious layers that could lead to reduced surface runoff and increase the potential for surface water quality impairment;this could lead to a reduction in the capacity of surface water ecosystem to provide clean/recreational waters. The increase in the extent of surface water cover was at the expense of the wetlands that shrunk, thereby threatening the coastal ecosystem’s ability to provide services such as storm and wave protection, nutrient cycling, and the protection of wildlife habitat. There was also a decrease in the extent of Agricultural lands which could lead to loss of food and fiber during the study period. There is therefore an urgent need to formulate or intensify existing policies to regulate land use from an ecological health standpoint in order to ensure sustainability of the various ecosystems within the watersheds of the Lower Eastern Shore of Maryland in the US, and similar coastal locations elsewhere.展开更多
We developed a cost-based methodology to assess the value of forested watersheds to improve water quality in public water supplies. The developed methodology is applicable to other source watersheds to determine ecosy...We developed a cost-based methodology to assess the value of forested watersheds to improve water quality in public water supplies. The developed methodology is applicable to other source watersheds to determine ecosystem services for water quality. We assess the value of forest land for source water mitigation of total organic carbon (TOC) through the use of linked watershed and reservoir simulation models and cost-based valuation economics. Watershed modeling results indicated that expected urbanization will increase TOC loads to Converse Reservoir (Mobile, AL). Reservoir model results indicated that future median TOC concentrations increased by 1.1 mg·L-1 between 1992 and 2020 at the source water intake. Depending upon dynamic reservoir TOC concentrations, additional drinking water treatment with powdered activated carbon (PAC) often is necessary between May and October to comply with Safe Drinking Water Act regulations. The cost for additional treatment was calculated using minimum and maximum volume treated with simulated TOC concentrations at the source water intake. Daily simulated TOC concentrations for the base scenario using 1992 land cover (3% urban) were compared with simulated TOC concentrations following forest to urban land conversion predicted in the watershed by 2020 (22% urban). The daily cost for additional drinking water treatment with PAC was calculated if simulated TOC concentrations exceeded 2.7 mg·L-1. The mean increase in daily treatment costs between base and future scenarios ranged from $91 to $95 per km2 per day for forest land water purification ecosystem services.展开更多
The Ili River Delta(IRD)is an ecological security barrier for the Lake Balkhash and an important water conservation area in Central Asia.In this study,we selected the IRD as a typical research area,and simulated the w...The Ili River Delta(IRD)is an ecological security barrier for the Lake Balkhash and an important water conservation area in Central Asia.In this study,we selected the IRD as a typical research area,and simulated the water yield and water conservation from 1975 to 2020 using the water yield module of the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model.We further analyzed the temporal and spatial variations in the water yield and water conservation in the IRD from 1975 to 2020,and investigated the main driving factors(precipitation,potential evapotranspiration,land use/land cover change,and inflow from the Ili River)of the water conservation variation based on the linear regression,piecewise linear regression,and Pearson's correlation coefficient analyses.The results indicated that from 1975 to 2020,the water yield and water conservation in the IRD showed a decreasing trend,and the spatial distribution pattern was"high in the east and low in the west";overall,the water conservation of all land use types decreased slightly.The water conservation volume of grassland was the most reduced,although the area of grassland increased owing to the increased inflow from the Ili River.At the same time,the increased inflow has led to the expansion of wetland areas,the improvement of vegetation growth,and the increase of regional evapotranspiration,thus resulting in an overall reduction in the water conservation.The water conservation depth and precipitation had similar spatial distribution patterns;the change in climate factors was the main reason for the decline in the water conservation function in the delta.The reservoir in the upper reaches of the IRD regulated runoff into the Lake Balkhash,promoted vegetation restoration,and had a positive effect on the water conservation;however,this positive effect cannot offset the negative effect of enhanced evapotranspiration.These results provide a reference for the rational allocation of water resources and ecosystem protection in the IRD.展开更多
Our case study analyzed the proximity of previously mapped fractures in the aquifer matrix to 93 Florida panther (Puma concolor coryi) dens mapped from 2007-2016 in south Florida. Dens occurred in five counties (Colli...Our case study analyzed the proximity of previously mapped fractures in the aquifer matrix to 93 Florida panther (Puma concolor coryi) dens mapped from 2007-2016 in south Florida. Dens occurred in five counties (Collier = 77, Dade = 1, Hendry = 9, Lee = 5, and Monroe = 1) and three sub-basins of the Greater Everglades Basin (Big Cypress Swamp = 83, Caloosahatchee = 3, and Everglades = 7). Fractured aquifers occur worldwide, but are not the focus of habitat suitability studies, despite evidence that fractures influence plant species composition and density. Habitat alterations can occur many kilometers from the surface footprint of groundwater alterations in the regional Floridan aquifer system via preferential flow through fractures. Increased natural discharge from and recharge to the aquifer occur at fracture intersections. Greater induced recharge and habitat changes also may occur at fracture intersections. All dens were within 5 km of a previously mapped fracture;36% and 74% were within 1 km and 2 km, respectively, of those fractures;and 47%, 74%, and 90% of dens were within 2 km, 3.25 km and 5 km, respectively, from the nearest fracture intersection. Results suggest fractures influence the suitability and/or availability of habitat for panther dens, selection of den sites, and availability as well as abundance of high quality prey items essential for the nutritional demands of successfully rearing panther kittens in the wild. We recommend more detailed investigations of: a) vegetation characteristics near dens, b) groundwater alterations and cumulative impacts of those alterations associated with fractures in panther habitat (e.g., altered plant species composition and density), and c) influence of aquifer fractures in all habitats underlain by fractures.展开更多
Land use/land cover(LULC)change and climate change are two major factors affecting the provision of ecosystem services which are closely related to human well-being.However,a clear understanding of the relationships b...Land use/land cover(LULC)change and climate change are two major factors affecting the provision of ecosystem services which are closely related to human well-being.However,a clear understanding of the relationships between these two factors and ecosystem services in Central Asia is still lacking.This study aimed to comprehensively assess ecosystem services in Central Asia and analyze how they are impacted by changes in LULC and climate.The spatiotemporal patterns of three ecosystem services during the period of 2000-2015,namely the net primary productivity(NPP),water yield,and soil retention,were quantified and mapped by the Carnegie-Ames-Stanford Approach(CASA)model,Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model,and Revised Universal Soil Loss Equation(RUSLE).Scenarios were used to determine the relative importance and combined effect of LULC change and climate change on ecosystem services.Then,the relationships between climate factors(precipitation and temperature)and ecosystem services,as well as between LULC change and ecosystem services,were further discussed.The results showed that the high values of ecosystem services appeared in the southeast of Central Asia.Among the six biomes(alpine forest region(AFR),alpine meadow region(AMR),typical steppe region(TSR),desert steppe region(DSR),desert region(DR),and lake region(LR)),the values of ecosystem services followed the order of AFR>AMR>TSR>DSR>DR>LR.In addition,the values of ecosystem services fluctuated during the period of 2000-2015,with the most significant decreases observed in the southeast mountainous area and northwest of Central Asia.LULC change had a greater impact on the NPP,while climate change had a stronger influence on the water yield and soil retention.The combined LULC change and climate change exhibited a significant synergistic effect on ecosystem services in most of Central Asia.Moreover,ecosystem services were more strongly and positively correlated with precipitation than with temperature.The greening of desert areas and forest land expansion could improve ecosystem services,but unreasonable development of cropland and urbanization have had an adverse impact on ecosystem services.According to the results,ecological stability in Central Asia can be achieved through the natural vegetation protection,reasonable urbanization,and ecological agriculture development.展开更多
Ecosystem-scale water use efficiency (WUE),as a quantification of the coupling between carbon and water cycle,determines whether vegetation could survive under severe drought stress.Nevertheless,how extreme droughts a...Ecosystem-scale water use efficiency (WUE),as a quantification of the coupling between carbon and water cycle,determines whether vegetation could survive under severe drought stress.Nevertheless,how extreme droughts affect ecosystem-scale WUE and its difference among regions and biomes are still poorly understood.In this study,using data-oriented gridded products of gross primary productivity (GPP) and evapotranspiration (ET),we assessed the ecosystem WUE change during extreme drought years over China,and further compared drought impacts on WUE between forest and grassland ecosystems.We found a spatial heterogeneity of WUE change in response to extreme droughts across regions.Particularly,grassland WUE was substantially reduced concurrent with suppressed photosynthesis,while most of forest exhibited slightly decreased or even increased WUE under extreme droughts.In addition,we demonstrated that drought characteristics and environmental conditions modulated drought impacts on WUE.Temperature anomalies during droughts and leaf area were found to be the predominant factors driving WUE change for both forest and grassland.With increasing occurrence of compound dry and hot extremes,our results,therefore,would be an insightful supplement to the current understanding of the influence of extreme events on terrestrial ecosystems.展开更多
Headwater streams play a major role for provision of ecosystem services,e.g.drinking water.We investigated a high-altitude headwater catchment of the Kharaa River(including 411st-order rivers)to understand the impact ...Headwater streams play a major role for provision of ecosystem services,e.g.drinking water.We investigated a high-altitude headwater catchment of the Kharaa River(including 411st-order rivers)to understand the impact of land cover(especially forest cover),environment and human usage on runoff,chemical water quality and macroinvertebrate fauna in a river basin under discontinuous permafrost conditions in an arid,sparsely populated region of Mongolia.To verify our hypotheses that different landuses and environmental impacts in permafrost headwaters influence water quality,we investigated 105 sampling sites,37 of them at intermittent stream sections without water flow.Discharge was positively impacted by land cover types steppe,grassland and forest and negatively by shrubland,forest burnt by wild fires(indicating a reduction of permafrost)and slope.Water quality was affected by altitude,longitude and latitude,shrub growth and water temperature.Shannon diversity of macroinvertebrates was driven by water temperature,iron content of the water,flow velocity,and subbasin size(adjusted R^(2)=0.54).Sample plots clustered in three groups that differed in water chemistry,macroinvertebrate diversity,species composition and bio-indicators.Our study confirms that steppes and grasslands have a higher contribution to runoff than forests,forest cover has a positive impact on water quality,and diversity of macroinvertebrates is higher in sites with less nutrients and pollutants.The excellent ecological status of the upper reaches of the Kharaa is severely threatened by forest fires and human-induced climate change and urgently needs to be conserved.展开更多
Introduction:Understanding the differences in carbon and water vapor fluxes of spatially distributed evergreen needleleaf forests(ENFs)is crucial for accurately estimating regional or global carbon and water budgets a...Introduction:Understanding the differences in carbon and water vapor fluxes of spatially distributed evergreen needleleaf forests(ENFs)is crucial for accurately estimating regional or global carbon and water budgets and when predicting the responses of ENFs to current and future climate.Methods:We compared the fluxes of ten AmeriFlux ENF sites to investigate cross-site variability in net ecosystem exchange of carbon(NEE),gross primary production(GPP),and evapotranspiration(ET).We used wavelet cross-correlation analysis to examine responses of NEE and ET to common climatic drivers over multiple timescales and also determined optimum values of air temperature(T_(a))and vapor pressure deficit(VPD)for NEE and ET.Results:We found larger differences in the NEE spectra than in the ET spectra across sites,demonstrating that spatial(site-to-site)variability was larger for NEE than for ET.The NEE and ET were decoupled differently across ENF sites because the wavelet cospectra between ET and climate variables were similar at all sites,while the wavelet cospectra between NEE and climate variables were higher(i.e.,closer coupling between NEE and climatic drivers)in semi-arid and Mediterranean sites than in other sites.Ecosystem water use efficiency(EWUE)based on annual GPP/ET ranged from 1.3±0.18 to 4.08±0.62 g C mm^(−1) ET,while EWUE based on annual net ecosystem production(NEP)/ET ranged from 0.06±0.04 to 1.02±0.16 g C mm^(−1) ET)among ENFs.Responses of NEE and ET to T_(a) varied across climatic zones.In particular,for ENF sites in semi-arid and Mediterranean climates,the maximum NEE and ET occurred at lower ranges of T_(a) than in sites with warm and humid summers.The optimum T_(a) and VPD values were higher for ET than for NEE,and ET was less sensitive to high values of T_(a) and VPD.Conclusions:Large spatial variability in carbon and water vapor fluxes among ENFs and large variations in responses of NEE and ET to major climate variables among climatic zones necessitate sub-plant functional type parameterization based on climatic zones to better represent climate sensitivity of ENFs and to reduce uncertainty in model predictions.展开更多
The capacity of six water stress factors(ε′(i))to track daily light use efficiency(ε)of water-limited ecosystems was evaluated.These factors are computed with remote sensing operational products and a limited amoun...The capacity of six water stress factors(ε′(i))to track daily light use efficiency(ε)of water-limited ecosystems was evaluated.These factors are computed with remote sensing operational products and a limited amount of ground data:ε′1 uses ground precipitation and air temperature,and satellite incoming global solar radiation;ε′(2) uses ground air temperature,and satellite actual evapotranspiration and incoming global solar radiation;ε′_(3) uses satellite actual and potential evapotranspiration;ε′_(4) uses satellite soil moisture;ε′_(5) uses satellite-derived photochemical reflectance index;and ε′_(6) uses ground vapor pressure deficit.These factors were implemented in a production efficiency model based on Monteith’s approach in order to assess their performance for modeling gross primary production(GPP).Estimated GPP was compared to reference GPP from eddy covariance(EC)measurements(GPP EC)in three sites placed in the Iberian Peninsula(two open shrublands and one savanna).ε′_(i) were correlated to ε,which was calculated by dividing GPP EC by ground measured photosynthetically active radiation(PAR)and satellite-derived fraction of absorbed PAR.Best results were achieved by ε′(1),ε′(2),ε′(3) and ε′(4) explaining around 40% and 50% of ε variance in open shurblands and savanna,respectively.In terms of GPP,R^(2)≈0.70 were obtained in these cases.展开更多
Xinjiang is the largest semi-arid and arid region in China, and drip irrigation under plastic mulch is widely used in this water-limited area. Quantifying carbon and water fluxes as well as investigating their environ...Xinjiang is the largest semi-arid and arid region in China, and drip irrigation under plastic mulch is widely used in this water-limited area. Quantifying carbon and water fluxes as well as investigating their environ- mental drivers over cotton fields is critical for understanding regional carbon and water budgets in Xinjiang, the largest cotton production basin of China. In this study, an eddy covariance (EC) technique was used to measure the carbon and water fluxes of cotton field under drip irrigation with plastic mulch in the growing seasons of 2009, 2010, 2012 and 2013 at Wulanwusu Agrometeorological Experiment Station, a representative oasis cropland in northern Xinjiang. The diurnal patterns of gross primary production (GPP), net ecosystem exchange (NEE) and evapotran-spiration (ET) showed obviously sinusoidal variations from June to September, while the diurnal ecosystem respiration (Res) was stable between daytime and nighttime. The daytime hourly GPP and ET displayed asymptotic rela-tionships with net solar radiation (Rnet), while showed concave patterns with raising vapor pressure deficit (VPD) and air temperature (Ta). The increases in hourly GPP and ET towards the maximum occurred over half ranges of VPD and Ta. The seasonal variations of GPP, NEE and ET were close to the cotton phenology, which almost reached the peak value in July. The cumulative GPP averaged 816.2±55.0 g C/m^2 in the growing season (from April to October), and more than half of GPP was partitioned into NEE (mean value of -478.6±41.4 g C/m^2). The mean seasonal ET was 501.3±13.9 mm, and the mean water use efficiency (WUE) was 1.0+0.1 (mg C/g H2O)/d. The agro-ecosystem behaved as a carbon sink from squaring to harvest period, while it acted as a carbon source before the squaring time as well as after the harvest time.展开更多
The interactions among industrial development,land use/cover change (LUCC), and environmentaleffects in Changshu in the eastern coastal China wereanalyzed using high-resolution Landsat TM data in 1990,1995, 2000, and ...The interactions among industrial development,land use/cover change (LUCC), and environmentaleffects in Changshu in the eastern coastal China wereanalyzed using high-resolution Landsat TM data in 1990,1995, 2000, and 2006, socio-economic data and waterenvironmental quality monitoring data from researchinstitutes and governmental departments. Three phases ofindustrial development in Changshu were examined (i.e.,the three periods of 1990 to 1995, 1995 to 2000, and 2000to 2006). Besides industrial development and rapidurbanization, land use/cover in Changshu had changeddrastically from 1990 to 2006. This change was characterizedby major replacements of farmland by urban and ruralsettlements, artificial ponds, forested and constructed land.Industrialization, urbanization, agricultural structureadjustment, and rural housing construction were themajor socio-economic driving forces of LUCC inChangshu. In addition, the annual value of ecosystemservices in Changshu decreased slightly during 1990-2000, but increased significantly during 2000-2006.Nevertheless, the local environmental quality in Changshu,especially in rural areas, has not yet been improvedsignificantly. Thus, this paper suggests an increasedattention to fully realize the role of land supply inadjustment of environment-friendly industrial structureand urban-rural spatial restructuring, and translating theland management and environmental protection policiesinto an optimized industrial distribution and land-use pattern.展开更多
文摘Ecosystem services are a key to human survival and global sustainability. Consequently, there is the need to avoid unscrupulous or unplanned land use practices that can compromise these services in addition to the ongoing changes in the global climate whose potentially negative impact are yet to be fully comprehended thus far. The primary objective of this study was to evaluate the Land use—land cover changes of some Eastern Shore sub-watersheds of Maryland from 1986-2006 and qualitatively assess the impact of the changes on some key ecosystem services. Landsat-TM data for Maryland Eastern Shore in the United States were analyzed in ENVI and ArcGIS environment and data interpreted qualitatively. The result showed that forest lands increased during the study period and thus enhanced carbon sequestration favorable for mitigating global warming in the area. Also, the extent of surface water cover increased slightly, possibly due to rising sea level and a thus a potential threat to biodiversity and barrier islands nearby. There was also a significant increase in urban lands due to population increase and thus increase in the extent of impervious layers that could lead to reduced surface runoff and increase the potential for surface water quality impairment;this could lead to a reduction in the capacity of surface water ecosystem to provide clean/recreational waters. The increase in the extent of surface water cover was at the expense of the wetlands that shrunk, thereby threatening the coastal ecosystem’s ability to provide services such as storm and wave protection, nutrient cycling, and the protection of wildlife habitat. There was also a decrease in the extent of Agricultural lands which could lead to loss of food and fiber during the study period. There is therefore an urgent need to formulate or intensify existing policies to regulate land use from an ecological health standpoint in order to ensure sustainability of the various ecosystems within the watersheds of the Lower Eastern Shore of Maryland in the US, and similar coastal locations elsewhere.
文摘We developed a cost-based methodology to assess the value of forested watersheds to improve water quality in public water supplies. The developed methodology is applicable to other source watersheds to determine ecosystem services for water quality. We assess the value of forest land for source water mitigation of total organic carbon (TOC) through the use of linked watershed and reservoir simulation models and cost-based valuation economics. Watershed modeling results indicated that expected urbanization will increase TOC loads to Converse Reservoir (Mobile, AL). Reservoir model results indicated that future median TOC concentrations increased by 1.1 mg·L-1 between 1992 and 2020 at the source water intake. Depending upon dynamic reservoir TOC concentrations, additional drinking water treatment with powdered activated carbon (PAC) often is necessary between May and October to comply with Safe Drinking Water Act regulations. The cost for additional treatment was calculated using minimum and maximum volume treated with simulated TOC concentrations at the source water intake. Daily simulated TOC concentrations for the base scenario using 1992 land cover (3% urban) were compared with simulated TOC concentrations following forest to urban land conversion predicted in the watershed by 2020 (22% urban). The daily cost for additional drinking water treatment with PAC was calculated if simulated TOC concentrations exceeded 2.7 mg·L-1. The mean increase in daily treatment costs between base and future scenarios ranged from $91 to $95 per km2 per day for forest land water purification ecosystem services.
基金funded by the National Natural Science Foundation of China(42071245)the Xinjiang Uygur Autonomous Region Innovation Environment Construction Special Project&Science and Technology Innovation Base Construction Project(PT2107)+2 种基金the Third Xinjiang Comprehensive Scientific Survey Project Sub-topic(2021xjkk140305)the Tianshan Talent Training Program of Xinjiang Uygur Autonomous Region(2022TSYCLJ0011)the K.C.Wong Education Foundation(GJTD-2020-14).
文摘The Ili River Delta(IRD)is an ecological security barrier for the Lake Balkhash and an important water conservation area in Central Asia.In this study,we selected the IRD as a typical research area,and simulated the water yield and water conservation from 1975 to 2020 using the water yield module of the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model.We further analyzed the temporal and spatial variations in the water yield and water conservation in the IRD from 1975 to 2020,and investigated the main driving factors(precipitation,potential evapotranspiration,land use/land cover change,and inflow from the Ili River)of the water conservation variation based on the linear regression,piecewise linear regression,and Pearson's correlation coefficient analyses.The results indicated that from 1975 to 2020,the water yield and water conservation in the IRD showed a decreasing trend,and the spatial distribution pattern was"high in the east and low in the west";overall,the water conservation of all land use types decreased slightly.The water conservation volume of grassland was the most reduced,although the area of grassland increased owing to the increased inflow from the Ili River.At the same time,the increased inflow has led to the expansion of wetland areas,the improvement of vegetation growth,and the increase of regional evapotranspiration,thus resulting in an overall reduction in the water conservation.The water conservation depth and precipitation had similar spatial distribution patterns;the change in climate factors was the main reason for the decline in the water conservation function in the delta.The reservoir in the upper reaches of the IRD regulated runoff into the Lake Balkhash,promoted vegetation restoration,and had a positive effect on the water conservation;however,this positive effect cannot offset the negative effect of enhanced evapotranspiration.These results provide a reference for the rational allocation of water resources and ecosystem protection in the IRD.
文摘Our case study analyzed the proximity of previously mapped fractures in the aquifer matrix to 93 Florida panther (Puma concolor coryi) dens mapped from 2007-2016 in south Florida. Dens occurred in five counties (Collier = 77, Dade = 1, Hendry = 9, Lee = 5, and Monroe = 1) and three sub-basins of the Greater Everglades Basin (Big Cypress Swamp = 83, Caloosahatchee = 3, and Everglades = 7). Fractured aquifers occur worldwide, but are not the focus of habitat suitability studies, despite evidence that fractures influence plant species composition and density. Habitat alterations can occur many kilometers from the surface footprint of groundwater alterations in the regional Floridan aquifer system via preferential flow through fractures. Increased natural discharge from and recharge to the aquifer occur at fracture intersections. Greater induced recharge and habitat changes also may occur at fracture intersections. All dens were within 5 km of a previously mapped fracture;36% and 74% were within 1 km and 2 km, respectively, of those fractures;and 47%, 74%, and 90% of dens were within 2 km, 3.25 km and 5 km, respectively, from the nearest fracture intersection. Results suggest fractures influence the suitability and/or availability of habitat for panther dens, selection of den sites, and availability as well as abundance of high quality prey items essential for the nutritional demands of successfully rearing panther kittens in the wild. We recommend more detailed investigations of: a) vegetation characteristics near dens, b) groundwater alterations and cumulative impacts of those alterations associated with fractures in panther habitat (e.g., altered plant species composition and density), and c) influence of aquifer fractures in all habitats underlain by fractures.
基金This study was supported by the Strategic Priority Research Program of Chinese Academy of Sciences,the Pan-Third Pole Environment Study for a Green Silk Road(Pan-TPE)(XDA2004030202).
文摘Land use/land cover(LULC)change and climate change are two major factors affecting the provision of ecosystem services which are closely related to human well-being.However,a clear understanding of the relationships between these two factors and ecosystem services in Central Asia is still lacking.This study aimed to comprehensively assess ecosystem services in Central Asia and analyze how they are impacted by changes in LULC and climate.The spatiotemporal patterns of three ecosystem services during the period of 2000-2015,namely the net primary productivity(NPP),water yield,and soil retention,were quantified and mapped by the Carnegie-Ames-Stanford Approach(CASA)model,Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model,and Revised Universal Soil Loss Equation(RUSLE).Scenarios were used to determine the relative importance and combined effect of LULC change and climate change on ecosystem services.Then,the relationships between climate factors(precipitation and temperature)and ecosystem services,as well as between LULC change and ecosystem services,were further discussed.The results showed that the high values of ecosystem services appeared in the southeast of Central Asia.Among the six biomes(alpine forest region(AFR),alpine meadow region(AMR),typical steppe region(TSR),desert steppe region(DSR),desert region(DR),and lake region(LR)),the values of ecosystem services followed the order of AFR>AMR>TSR>DSR>DR>LR.In addition,the values of ecosystem services fluctuated during the period of 2000-2015,with the most significant decreases observed in the southeast mountainous area and northwest of Central Asia.LULC change had a greater impact on the NPP,while climate change had a stronger influence on the water yield and soil retention.The combined LULC change and climate change exhibited a significant synergistic effect on ecosystem services in most of Central Asia.Moreover,ecosystem services were more strongly and positively correlated with precipitation than with temperature.The greening of desert areas and forest land expansion could improve ecosystem services,but unreasonable development of cropland and urbanization have had an adverse impact on ecosystem services.According to the results,ecological stability in Central Asia can be achieved through the natural vegetation protection,reasonable urbanization,and ecological agriculture development.
基金Supported by the National Natural Science Foundation of China (42105160)。
文摘Ecosystem-scale water use efficiency (WUE),as a quantification of the coupling between carbon and water cycle,determines whether vegetation could survive under severe drought stress.Nevertheless,how extreme droughts affect ecosystem-scale WUE and its difference among regions and biomes are still poorly understood.In this study,using data-oriented gridded products of gross primary productivity (GPP) and evapotranspiration (ET),we assessed the ecosystem WUE change during extreme drought years over China,and further compared drought impacts on WUE between forest and grassland ecosystems.We found a spatial heterogeneity of WUE change in response to extreme droughts across regions.Particularly,grassland WUE was substantially reduced concurrent with suppressed photosynthesis,while most of forest exhibited slightly decreased or even increased WUE under extreme droughts.In addition,we demonstrated that drought characteristics and environmental conditions modulated drought impacts on WUE.Temperature anomalies during droughts and leaf area were found to be the predominant factors driving WUE change for both forest and grassland.With increasing occurrence of compound dry and hot extremes,our results,therefore,would be an insightful supplement to the current understanding of the influence of extreme events on terrestrial ecosystems.
基金This research was financially supported by the German Federal Ministry for Economic Cooperation and Development(grant number:BMZ 81212690)and a‘Forschung vor Ort’grant for G.K.of the Max Weber-Program of the State of Bavaria.Special thanks are due to the Deutsche Gesellschaft für Internationale Zusammenarbeit(GIZ)GmbH,especially Klaus Schmidt-Corsitto,at that time Programme Director for“Biodiversity and Adaptation of Key Forest Ecosystems to Climate Change II Program”of GIZ and many employees of GIZ Mongolia.
文摘Headwater streams play a major role for provision of ecosystem services,e.g.drinking water.We investigated a high-altitude headwater catchment of the Kharaa River(including 411st-order rivers)to understand the impact of land cover(especially forest cover),environment and human usage on runoff,chemical water quality and macroinvertebrate fauna in a river basin under discontinuous permafrost conditions in an arid,sparsely populated region of Mongolia.To verify our hypotheses that different landuses and environmental impacts in permafrost headwaters influence water quality,we investigated 105 sampling sites,37 of them at intermittent stream sections without water flow.Discharge was positively impacted by land cover types steppe,grassland and forest and negatively by shrubland,forest burnt by wild fires(indicating a reduction of permafrost)and slope.Water quality was affected by altitude,longitude and latitude,shrub growth and water temperature.Shannon diversity of macroinvertebrates was driven by water temperature,iron content of the water,flow velocity,and subbasin size(adjusted R^(2)=0.54).Sample plots clustered in three groups that differed in water chemistry,macroinvertebrate diversity,species composition and bio-indicators.Our study confirms that steppes and grasslands have a higher contribution to runoff than forests,forest cover has a positive impact on water quality,and diversity of macroinvertebrates is higher in sites with less nutrients and pollutants.The excellent ecological status of the upper reaches of the Kharaa is severely threatened by forest fires and human-induced climate change and urgently needs to be conserved.
基金supported in part by grants from the Agriculture and Food Research Initiative of the USDA National Institute of Food and Agriculture(NIFA,Grant No.2013-69002 to P.Wagle,X.Xiao,and P.Gowda,and Grant No.2013-67003-20652 to B.Law)the National Science Foundation EPSCoR(IIA-1301789 to X.Xiao)+8 种基金supported by US Department of Energy(Grant No.65076)to B.Lawsupported by the North American Carbon Program/USDA CREES NRI(2004-35111-15057,2008-35101-19076)Science Foundation Arizona(CAA 0-203-08)to T.Kolbsupported by grants from US Department of Energy[the National Institute for Climate Change Research(NICCR)and Terrestrial Carbon Processes Program(TCP)]the National Science Foundation Environmental Biology(Grant 0918565)supported by an agreement among the University of Washington,the Pacific Northwest Research Station,and the Gifford Pinchot National Forestsupported by DOE BER-TES awards number 7090112 and 11-DE-SC-0006700USDA NIFA CAP 560 Award 2011-68002-30185USDA Forest Service Eastern Forest Environmental Threat Assessment Center Grant 08-JV-11330147-038。
文摘Introduction:Understanding the differences in carbon and water vapor fluxes of spatially distributed evergreen needleleaf forests(ENFs)is crucial for accurately estimating regional or global carbon and water budgets and when predicting the responses of ENFs to current and future climate.Methods:We compared the fluxes of ten AmeriFlux ENF sites to investigate cross-site variability in net ecosystem exchange of carbon(NEE),gross primary production(GPP),and evapotranspiration(ET).We used wavelet cross-correlation analysis to examine responses of NEE and ET to common climatic drivers over multiple timescales and also determined optimum values of air temperature(T_(a))and vapor pressure deficit(VPD)for NEE and ET.Results:We found larger differences in the NEE spectra than in the ET spectra across sites,demonstrating that spatial(site-to-site)variability was larger for NEE than for ET.The NEE and ET were decoupled differently across ENF sites because the wavelet cospectra between ET and climate variables were similar at all sites,while the wavelet cospectra between NEE and climate variables were higher(i.e.,closer coupling between NEE and climatic drivers)in semi-arid and Mediterranean sites than in other sites.Ecosystem water use efficiency(EWUE)based on annual GPP/ET ranged from 1.3±0.18 to 4.08±0.62 g C mm^(−1) ET,while EWUE based on annual net ecosystem production(NEP)/ET ranged from 0.06±0.04 to 1.02±0.16 g C mm^(−1) ET)among ENFs.Responses of NEE and ET to T_(a) varied across climatic zones.In particular,for ENF sites in semi-arid and Mediterranean climates,the maximum NEE and ET occurred at lower ranges of T_(a) than in sites with warm and humid summers.The optimum T_(a) and VPD values were higher for ET than for NEE,and ET was less sensitive to high values of T_(a) and VPD.Conclusions:Large spatial variability in carbon and water vapor fluxes among ENFs and large variations in responses of NEE and ET to major climate variables among climatic zones necessitate sub-plant functional type parameterization based on climatic zones to better represent climate sensitivity of ENFs and to reduce uncertainty in model predictions.
基金This work was partially funded by the RESET CLIMATE(CGL2012-35831)the ESCENARIOS(CGL2016-75239-R)+1 种基金the PROMISES(ESP2015-67549-C3)projects from the Spanish Ministry of Economy and Competitivenessby the LSA SAF CDOP-2 project from the European Organization for the Exploitaition of Meteorological Satellites(EUMETSAT).
文摘The capacity of six water stress factors(ε′(i))to track daily light use efficiency(ε)of water-limited ecosystems was evaluated.These factors are computed with remote sensing operational products and a limited amount of ground data:ε′1 uses ground precipitation and air temperature,and satellite incoming global solar radiation;ε′(2) uses ground air temperature,and satellite actual evapotranspiration and incoming global solar radiation;ε′_(3) uses satellite actual and potential evapotranspiration;ε′_(4) uses satellite soil moisture;ε′_(5) uses satellite-derived photochemical reflectance index;and ε′_(6) uses ground vapor pressure deficit.These factors were implemented in a production efficiency model based on Monteith’s approach in order to assess their performance for modeling gross primary production(GPP).Estimated GPP was compared to reference GPP from eddy covariance(EC)measurements(GPP EC)in three sites placed in the Iberian Peninsula(two open shrublands and one savanna).ε′_(i) were correlated to ε,which was calculated by dividing GPP EC by ground measured photosynthetically active radiation(PAR)and satellite-derived fraction of absorbed PAR.Best results were achieved by ε′(1),ε′(2),ε′(3) and ε′(4) explaining around 40% and 50% of ε variance in open shurblands and savanna,respectively.In terms of GPP,R^(2)≈0.70 were obtained in these cases.
基金supported by the West Light Foundation of the Chinese Academy of Sciences (XBBS201110)the National Natural Science Foundation of China (41101101)the Chinese Academy of Sciences Key Deployment Project (KZZDEW-08-02-02)
文摘Xinjiang is the largest semi-arid and arid region in China, and drip irrigation under plastic mulch is widely used in this water-limited area. Quantifying carbon and water fluxes as well as investigating their environ- mental drivers over cotton fields is critical for understanding regional carbon and water budgets in Xinjiang, the largest cotton production basin of China. In this study, an eddy covariance (EC) technique was used to measure the carbon and water fluxes of cotton field under drip irrigation with plastic mulch in the growing seasons of 2009, 2010, 2012 and 2013 at Wulanwusu Agrometeorological Experiment Station, a representative oasis cropland in northern Xinjiang. The diurnal patterns of gross primary production (GPP), net ecosystem exchange (NEE) and evapotran-spiration (ET) showed obviously sinusoidal variations from June to September, while the diurnal ecosystem respiration (Res) was stable between daytime and nighttime. The daytime hourly GPP and ET displayed asymptotic rela-tionships with net solar radiation (Rnet), while showed concave patterns with raising vapor pressure deficit (VPD) and air temperature (Ta). The increases in hourly GPP and ET towards the maximum occurred over half ranges of VPD and Ta. The seasonal variations of GPP, NEE and ET were close to the cotton phenology, which almost reached the peak value in July. The cumulative GPP averaged 816.2±55.0 g C/m^2 in the growing season (from April to October), and more than half of GPP was partitioned into NEE (mean value of -478.6±41.4 g C/m^2). The mean seasonal ET was 501.3±13.9 mm, and the mean water use efficiency (WUE) was 1.0+0.1 (mg C/g H2O)/d. The agro-ecosystem behaved as a carbon sink from squaring to harvest period, while it acted as a carbon source before the squaring time as well as after the harvest time.
基金This work was supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(No.KZCX2-YWQN304)the National Natural Science Foundation of China(Grant Nos.40771014 and 40635029)the Ministry of Science and Technology of China(No.2007BAC03A11-01).
文摘The interactions among industrial development,land use/cover change (LUCC), and environmentaleffects in Changshu in the eastern coastal China wereanalyzed using high-resolution Landsat TM data in 1990,1995, 2000, and 2006, socio-economic data and waterenvironmental quality monitoring data from researchinstitutes and governmental departments. Three phases ofindustrial development in Changshu were examined (i.e.,the three periods of 1990 to 1995, 1995 to 2000, and 2000to 2006). Besides industrial development and rapidurbanization, land use/cover in Changshu had changeddrastically from 1990 to 2006. This change was characterizedby major replacements of farmland by urban and ruralsettlements, artificial ponds, forested and constructed land.Industrialization, urbanization, agricultural structureadjustment, and rural housing construction were themajor socio-economic driving forces of LUCC inChangshu. In addition, the annual value of ecosystemservices in Changshu decreased slightly during 1990-2000, but increased significantly during 2000-2006.Nevertheless, the local environmental quality in Changshu,especially in rural areas, has not yet been improvedsignificantly. Thus, this paper suggests an increasedattention to fully realize the role of land supply inadjustment of environment-friendly industrial structureand urban-rural spatial restructuring, and translating theland management and environmental protection policiesinto an optimized industrial distribution and land-use pattern.