There is growing interest in using ecosystem services to aid development of management strategies that target sustainability and enhance ecosystem support to humans. Challenges remain in the search for methods and ind...There is growing interest in using ecosystem services to aid development of management strategies that target sustainability and enhance ecosystem support to humans. Challenges remain in the search for methods and indicators that can quantify ecosystem services using metrics that are meaningful in light of their high priorities. We developed a framework to link ecosystems to human wellbeing based on a stepwise approach. We evaluated prospective models in terms of their capacity to quantify national ecosystem services of forests. The most applicable models were subsequently used to quantify ecosystem services. The Korea Forest Research Institute model sat- isfied all criteria in its first practical use. A total of 12 key ecosystem services were identified. For our case study, we quantified four ecosystem functions, viz. water storage capacity in forest soil for water storage service, reduced suspended sediment for water purification service, reduced soil erosion for landslide prevention service, and reduced sediment yield for sediment regulation service. Water storage capacity in forest soil was estimated at 2142 t/ha, and reduced suspended sediment was estimated at 608 kg/ ha. Reduced soil erosion was estimated at 77 m^3/ha, and reduced sediment yield was estimated at 285 m^3/ha. These results were similar to those reported by previous studies. Mapped results revealed hotspots of ecosystem services around protected areas that were particularly rich in bio- diversity. In addition, the proposed framework illustrated that quantification of ecosystem services could be sup- ported by the spatial flow of ecosystem services. However, our approach did not address challenges faced when quantifying connections between ecosystem indicators and actual benefits of services described.展开更多
It is critical to study how different forest management practices affect forest carbon sequestration under global climate change regime. Previous researches focused on the stand-level forest carbon sequestration with ...It is critical to study how different forest management practices affect forest carbon sequestration under global climate change regime. Previous researches focused on the stand-level forest carbon sequestration with rare investigation of forest carbon stocks influ- enced by forest management practices and climate change at regional scale. In this study, a general integrative approach was used to simulate spatial and temporal variations of woody biomass and harvested biomass of forest in China during the 21st century under dif- ferent scenarios of climate and CO2 concentration changes and management tasks by coupling Integrated Terrestrial Ecosystem Carbon budget （InTEC） model with Global Forest Model （G4M）. The results showed that forest management practices have more predominant effects on forest stem stocking biomass than climate and CO2 concentration change. Meanwhile, the concurrent future changes in cli- mate and CO2 concentration will enhance the amounts of stem stocking biomass in forests of China by 12%-23% during 2001-2100 relative to that with climate change only. The task for maximizing stem stocking biomass will dramatically enhance the stem stocking biomass from 2001~100, while the task for maximum average increment will result in an increment of stem stocking biomass before 2050 then decline. The difference of woody biomass responding to forest management tasks was owing to the current age structure of forests in China. Meanwhile, the sensitivity of long-term woody biomass to management practices for different forest types （coniferous forest, mixed forest and deciduous forest） under changing climate and CO2 concentration was also analyzed. In addition, longer rotation length under future climate change and rising CO2 concentration scenario will dramatically increase the woody biomass of China during 2001~100. Therefore, our estimation indicated that taking the role of forest management in the carbon cycle into the consideration at regional or national level is very important to project the forest carbon sequestration under future climate change and rising atmospheric CO2 concentration.展开更多
The spatial distribution of cropland is an important input to many applications including food security monitoring and economic land use modeling. Global land cover maps derived from remote sensing are one source of c...The spatial distribution of cropland is an important input to many applications including food security monitoring and economic land use modeling. Global land cover maps derived from remote sensing are one source of cropland but they are currently not accurate enough in the cropland domain to meet the needs of the user community. Moreover, when compared with one another, these land cover products show large areas of spatial disagreement, which makes the choice very difficult regarding which land cover product to use. This paper takes an entirely different approach to mapping cropland, using crowdsourcing of Google Earth imagery via tools in Geo-Wiki. Using sample data generated by a crowdsourcing campaign for the collection of the degree of cultivation and settlement in Ethiopia, a cropland map was created using simple inverse distance weighted interpolation. The map was validated using data from the GOFC-GOLD validation portal and an independent crowdsourced dataset from Geo-Wiki. The results show that the crowdsourced cropland map for Ethiopia has a higher overall accuracy than the individual global land cover products for this country. Such an approach has great potential for mapping cropland in other countries where such data do not currently exist. Not only is the approach inexpensive but the data can be collected over a very short period of time using an existing network of volunteers.展开更多
Previous studies demonstrated climate change had reduced rice yield in China, but the magnitude of the reduction and the spatial variations of the impact have remained in controversy to date. Based on a gridded daily ...Previous studies demonstrated climate change had reduced rice yield in China, but the magnitude of the reduction and the spatial variations of the impact have remained in controversy to date. Based on a gridded daily weather dataset, we found there were obvious changes in temperatures, diurnal temperature range, and radiation during the rice-growing season from 1961 to 2010 in China. These changes resulted in a signiifcant decline of simulated national rice yield （simulated with CERES-Rice）, with a magnitude of 11.5%. However, changes in growing-season radiation and diurnal temperature range, not growing-season temperatures, contributed most to the simulated yield reduction, which conifrmed previous estimates by empirical studies. Yield responses to changes of the climatic variables varied across different rice production areas. In rice production areas with the mean growing-season temperature at 12-14＆#176;C and above 20＆#176;C, a 1＆#176;C growing-season warming decreased rice yield by roughly 4%. This decrease was partly attributed to increased heat stresses and shorter growth period under the warmer climate. In some rice areas of the southern China and the Yangtze River Basin where the rice growing-season temperature was greater than 20＆#176;C, decrease in the growing-season radiation partly interpreted the widespread yield decline of the simulation, suggesting the signiifcant negative contribution of recent global dimming on rice production in China＇s main rice areas. Whereas in the northern rice production areas with relatively low growing-season temperature, decrease of the diurnal temperature range was identiifed as the main climatic contributor for the decline of simulated rice yield, with larger decreasing magnitude under cooler areas.展开更多
Global land cover(LC)maps have been widely employed as the base layer for a number of applications including climate change,food security,water quality,biodiversity,change detection,and environmental planning.Due to t...Global land cover(LC)maps have been widely employed as the base layer for a number of applications including climate change,food security,water quality,biodiversity,change detection,and environmental planning.Due to the importance of LC,there is a pressing need to increase the temporal and spatial resolution of global LC maps.A recent advance in this direction has been the GlobeLand30 dataset derived from Landsat imagery,which has been developed by the National Geomatics Center of China(NGCC).Although overall accuracy is greater than 80%,the NGCC would like help in assessing the accuracy of the product in different regions of the world.To assist in this process,this study compares the GlobeLand30 product with existing public and online datasets,that is,CORINE,Urban Atlas(UA),OpenStreetMap,and ATKIS for Germany in order to assess overall and per class agreement.The results of the analysis reveal high agreement of up to 92%between these datasets and GlobeLand30 but that large disagreements for certain classes are evident,in particular wetlands.However,overall,GlobeLand30 is shown to be a useful product for characterizing LC in Germany,and paves the way for further regional and national validation efforts.展开更多
Volunteered geographic information(VGI)is the assembly of spatial information based on public input.While VGI has proliferated in recent years,assessing the quality of volunteer-contributed data has proven challenging...Volunteered geographic information(VGI)is the assembly of spatial information based on public input.While VGI has proliferated in recent years,assessing the quality of volunteer-contributed data has proven challenging,leading some to question the efficiency of such programs.In this paper,we compare several quality metrics for individual volunteers’contributions.The data were the product of the‘Cropland Capture’game,in which several thousand volunteers assessed 165,000 images for the presence of cropland over the course of 6 months.We compared agreement between volunteer ratings and an image’s majority classification with volunteer self-agreement on repeated images and expert evaluations.We also examined the impact of experience and learning on performance.Volunteer self-agreement was nearly always higher than agreement with majority classifications,and much greater than agreement with expert validations although these metrics were all positively correlated.Volunteer quality showed a broad trend toward improvement with experience,but the highest accuracies were achieved by a handful of moderately active contributors,not the most active volunteers.Our results emphasize the importance of a universal set of expert-validated tasks as a gold standard for evaluating VGI quality.展开更多
Crop-residue return is a recommended practice for soil and nutrient management and is important in soil organic carbon(SOC)sequestration and CO2 mitigation.We applied a process-based Environmental Policy Integrated Cl...Crop-residue return is a recommended practice for soil and nutrient management and is important in soil organic carbon(SOC)sequestration and CO2 mitigation.We applied a process-based Environmental Policy Integrated Climate(EPIC)model to simulate the spatial pattern of topsoil organic carbon changes from 2001 to 2010under 4 crop-residue return scenarios in China.The carbon loss(28.89 Tg yr–1)with all crop-residue removal(CR0%)was partly reduced by 22.38 Tg C yr–1 under the status quo CR30%(30% of crop-residue return).The topsoil in cropland of China would become a net carbon sink if the crop-residue return rate was increased from 30%to 50%,or even 75%.The national SOC sequestration potential of cropland was estimated to be 25.53 Tg C yr–1 in CR50%and 52.85 Tg C yr–1 in CR75%,but with high spatial variability across regions.The highest rate of SOC sequestration potential in density occurred in Northwest and North China while the lowest was in East China.Croplands in North China tended to have stronger regional SOC sequestration potential in storage.During the decade,the reduced CO2 emissions from enhanced topsoil carbon in CR50%and CR75% were equivalent to 1.4% and 2.9%of the total CO2 emissions from fossil fuels and cement production in China,respectively.In conclusion,we recommend encouraging farmers to return crop-residue instead of burning in order to improve soil properties and alleviate atmospheric CO2 rises,especially in North China.展开更多
基金supported by the Korea Ministry of Environment as ‘‘Climate Change Correspondence Program(2014001310008)’’ and ‘‘The Eco-Innovation Project(Project Number:2012-00021-0002)’’
文摘There is growing interest in using ecosystem services to aid development of management strategies that target sustainability and enhance ecosystem support to humans. Challenges remain in the search for methods and indicators that can quantify ecosystem services using metrics that are meaningful in light of their high priorities. We developed a framework to link ecosystems to human wellbeing based on a stepwise approach. We evaluated prospective models in terms of their capacity to quantify national ecosystem services of forests. The most applicable models were subsequently used to quantify ecosystem services. The Korea Forest Research Institute model sat- isfied all criteria in its first practical use. A total of 12 key ecosystem services were identified. For our case study, we quantified four ecosystem functions, viz. water storage capacity in forest soil for water storage service, reduced suspended sediment for water purification service, reduced soil erosion for landslide prevention service, and reduced sediment yield for sediment regulation service. Water storage capacity in forest soil was estimated at 2142 t/ha, and reduced suspended sediment was estimated at 608 kg/ ha. Reduced soil erosion was estimated at 77 m^3/ha, and reduced sediment yield was estimated at 285 m^3/ha. These results were similar to those reported by previous studies. Mapped results revealed hotspots of ecosystem services around protected areas that were particularly rich in bio- diversity. In addition, the proposed framework illustrated that quantification of ecosystem services could be sup- ported by the spatial flow of ecosystem services. However, our approach did not address challenges faced when quantifying connections between ecosystem indicators and actual benefits of services described.
基金Under the auspices of International Science and Technology Cooperation Project(No.2010DFA22480)Major State Basic Research Development Program of China(No.2010CB833503)
文摘It is critical to study how different forest management practices affect forest carbon sequestration under global climate change regime. Previous researches focused on the stand-level forest carbon sequestration with rare investigation of forest carbon stocks influ- enced by forest management practices and climate change at regional scale. In this study, a general integrative approach was used to simulate spatial and temporal variations of woody biomass and harvested biomass of forest in China during the 21st century under dif- ferent scenarios of climate and CO2 concentration changes and management tasks by coupling Integrated Terrestrial Ecosystem Carbon budget （InTEC） model with Global Forest Model （G4M）. The results showed that forest management practices have more predominant effects on forest stem stocking biomass than climate and CO2 concentration change. Meanwhile, the concurrent future changes in cli- mate and CO2 concentration will enhance the amounts of stem stocking biomass in forests of China by 12%-23% during 2001-2100 relative to that with climate change only. The task for maximizing stem stocking biomass will dramatically enhance the stem stocking biomass from 2001~100, while the task for maximum average increment will result in an increment of stem stocking biomass before 2050 then decline. The difference of woody biomass responding to forest management tasks was owing to the current age structure of forests in China. Meanwhile, the sensitivity of long-term woody biomass to management practices for different forest types （coniferous forest, mixed forest and deciduous forest） under changing climate and CO2 concentration was also analyzed. In addition, longer rotation length under future climate change and rising CO2 concentration scenario will dramatically increase the woody biomass of China during 2001~100. Therefore, our estimation indicated that taking the role of forest management in the carbon cycle into the consideration at regional or national level is very important to project the forest carbon sequestration under future climate change and rising atmospheric CO2 concentration.
文摘The spatial distribution of cropland is an important input to many applications including food security monitoring and economic land use modeling. Global land cover maps derived from remote sensing are one source of cropland but they are currently not accurate enough in the cropland domain to meet the needs of the user community. Moreover, when compared with one another, these land cover products show large areas of spatial disagreement, which makes the choice very difficult regarding which land cover product to use. This paper takes an entirely different approach to mapping cropland, using crowdsourcing of Google Earth imagery via tools in Geo-Wiki. Using sample data generated by a crowdsourcing campaign for the collection of the degree of cultivation and settlement in Ethiopia, a cropland map was created using simple inverse distance weighted interpolation. The map was validated using data from the GOFC-GOLD validation portal and an independent crowdsourced dataset from Geo-Wiki. The results show that the crowdsourced cropland map for Ethiopia has a higher overall accuracy than the individual global land cover products for this country. Such an approach has great potential for mapping cropland in other countries where such data do not currently exist. Not only is the approach inexpensive but the data can be collected over a very short period of time using an existing network of volunteers.
基金supported by the National Basic Research Program of China(2010CB951504,2012CB95590004)the National Natural Science Foundation of China(41171093)the Key Technologies R&D Program of China during the 12th Five-Year Plan period(2012BAC19B01)
文摘Previous studies demonstrated climate change had reduced rice yield in China, but the magnitude of the reduction and the spatial variations of the impact have remained in controversy to date. Based on a gridded daily weather dataset, we found there were obvious changes in temperatures, diurnal temperature range, and radiation during the rice-growing season from 1961 to 2010 in China. These changes resulted in a signiifcant decline of simulated national rice yield （simulated with CERES-Rice）, with a magnitude of 11.5%. However, changes in growing-season radiation and diurnal temperature range, not growing-season temperatures, contributed most to the simulated yield reduction, which conifrmed previous estimates by empirical studies. Yield responses to changes of the climatic variables varied across different rice production areas. In rice production areas with the mean growing-season temperature at 12-14＆#176;C and above 20＆#176;C, a 1＆#176;C growing-season warming decreased rice yield by roughly 4%. This decrease was partly attributed to increased heat stresses and shorter growth period under the warmer climate. In some rice areas of the southern China and the Yangtze River Basin where the rice growing-season temperature was greater than 20＆#176;C, decrease in the growing-season radiation partly interpreted the widespread yield decline of the simulation, suggesting the signiifcant negative contribution of recent global dimming on rice production in China＇s main rice areas. Whereas in the northern rice production areas with relatively low growing-season temperature, decrease of the diurnal temperature range was identiifed as the main climatic contributor for the decline of simulated rice yield, with larger decreasing magnitude under cooler areas.
基金The authors would also like to acknowledge the support and contribution of COST Action TD1202‘Mapping and the Citizen Sensor’as well as COST Action IC1203‘European Network Exploring Research into Geospatial Information Crowdsourcing’(ENERGIC).
文摘Global land cover(LC)maps have been widely employed as the base layer for a number of applications including climate change,food security,water quality,biodiversity,change detection,and environmental planning.Due to the importance of LC,there is a pressing need to increase the temporal and spatial resolution of global LC maps.A recent advance in this direction has been the GlobeLand30 dataset derived from Landsat imagery,which has been developed by the National Geomatics Center of China(NGCC).Although overall accuracy is greater than 80%,the NGCC would like help in assessing the accuracy of the product in different regions of the world.To assist in this process,this study compares the GlobeLand30 product with existing public and online datasets,that is,CORINE,Urban Atlas(UA),OpenStreetMap,and ATKIS for Germany in order to assess overall and per class agreement.The results of the analysis reveal high agreement of up to 92%between these datasets and GlobeLand30 but that large disagreements for certain classes are evident,in particular wetlands.However,overall,GlobeLand30 is shown to be a useful product for characterizing LC in Germany,and paves the way for further regional and national validation efforts.
基金supported by the European Research Council[grants 617754 and 603719]a IIASA postdoctoral fellowship to Carl Salk.
文摘Volunteered geographic information(VGI)is the assembly of spatial information based on public input.While VGI has proliferated in recent years,assessing the quality of volunteer-contributed data has proven challenging,leading some to question the efficiency of such programs.In this paper,we compare several quality metrics for individual volunteers’contributions.The data were the product of the‘Cropland Capture’game,in which several thousand volunteers assessed 165,000 images for the presence of cropland over the course of 6 months.We compared agreement between volunteer ratings and an image’s majority classification with volunteer self-agreement on repeated images and expert evaluations.We also examined the impact of experience and learning on performance.Volunteer self-agreement was nearly always higher than agreement with majority classifications,and much greater than agreement with expert validations although these metrics were all positively correlated.Volunteer quality showed a broad trend toward improvement with experience,but the highest accuracies were achieved by a handful of moderately active contributors,not the most active volunteers.Our results emphasize the importance of a universal set of expert-validated tasks as a gold standard for evaluating VGI quality.
基金The National Key Research and Development Program of China(2017YFC0503803)The National Key Research and Development Program of China(2016YFA0600202)+1 种基金General Program of National Natural Science Foundation of China(41571192)Science and Technology Planning Project of Hebei,China(17390313D)
文摘Crop-residue return is a recommended practice for soil and nutrient management and is important in soil organic carbon(SOC)sequestration and CO2 mitigation.We applied a process-based Environmental Policy Integrated Climate(EPIC)model to simulate the spatial pattern of topsoil organic carbon changes from 2001 to 2010under 4 crop-residue return scenarios in China.The carbon loss(28.89 Tg yr–1)with all crop-residue removal(CR0%)was partly reduced by 22.38 Tg C yr–1 under the status quo CR30%(30% of crop-residue return).The topsoil in cropland of China would become a net carbon sink if the crop-residue return rate was increased from 30%to 50%,or even 75%.The national SOC sequestration potential of cropland was estimated to be 25.53 Tg C yr–1 in CR50%and 52.85 Tg C yr–1 in CR75%,but with high spatial variability across regions.The highest rate of SOC sequestration potential in density occurred in Northwest and North China while the lowest was in East China.Croplands in North China tended to have stronger regional SOC sequestration potential in storage.During the decade,the reduced CO2 emissions from enhanced topsoil carbon in CR50%and CR75% were equivalent to 1.4% and 2.9%of the total CO2 emissions from fossil fuels and cement production in China,respectively.In conclusion,we recommend encouraging farmers to return crop-residue instead of burning in order to improve soil properties and alleviate atmospheric CO2 rises,especially in North China.
