The spatial distribution of vegetation in Qaidam Basin was analyzed using GIMMS（Global Inventory Modeling and Mapping Studies） /NDVI（Normalized Difference Vegetation Index） data set from January 1982 to December 2...The spatial distribution of vegetation in Qaidam Basin was analyzed using GIMMS（Global Inventory Modeling and Mapping Studies） /NDVI（Normalized Difference Vegetation Index） data set from January 1982 to December 2006.Based on the data of precipitation,terrain,stream systems,land use and the map of vegetation distribution in Qaidam Basin,we studied the factors influencing the spatial distribution of vegetation.The results showed that the vegetation was generally low in Qaidam Basin and there was a clear semi-ring structure from southeast to northwest.In some areas,the existence of rivers,lakes and spring belts turned this semi-ring structure into a non-continuous state and formed distinct bright spots and continuous linear features.There were four main factors that affected the spatial distribution of vegetation coverage in Qaidam Basin,i.e.,precipitation,hydrological conditions,altitude and human activities.Precipitation and altitude have a correlation and determine the basic pattern of vegetation distribution in Qaidam Basin.The impacts of hydrological conditions and human activities were mainly embodied in partial areas,and often broke the pattern of vegetation distribution dominated by precipitation and altitude.展开更多
The Three-River Source Region(TRSR),China's water tower and an important ecological barrier in China,provides a considerable amount of water to the downstream regions,home to more than 500 million people.The prese...The Three-River Source Region(TRSR),China's water tower and an important ecological barrier in China,provides a considerable amount of water to the downstream regions,home to more than 500 million people.The present study focused on the assessment of hydrological components(i.e.,precipitation,actual evapotranspiration,potential evapotranspiration,surface flow,baseflow,streamflow,soil moisture,snowmelt water,and terrestrial water storage),their transformation and trends along with meteorological elements(i.e.,maximum temperature,minimum temperature,mean temperature,relative humidity,wind speed,and sunshine hours)in the historical and future periods.For this,the hydrological model,HEC-HMS,was applied to simulate hydrological components and Mann-Kendal to explore the trends for 1981-2015.First time,the statistical downscaling model,SDSM,was used to generate climatic data under the shared socio-economic scenario-5(SSP585)in the region,which was applied to simulate the hydrological cycle.The assessment results showed that precipitation transformed into evapotranspiration and streamflow by 70% and 30%,respectively.In the region,streamflow was generated by 78%,22%,and 5.6% by baseflow,surface flow,and snowmelt.According to trend results,all climatic variables showed statistically significant trends but insignificant in all hydrological components for the historical period,except evapotranspiration.However,all hydroclimatic components were projected to increase in the future,except windspeed.For example,temperature,precipitation,evapotranspiration,streamflow,and direct flow(surface flow)will increase by 1.4(3.3)℃,12(36)%,8.5(19)%,25(95)%,and 77(473)% in 2021-2060(2061-2100)relative to 1981-2020,which shows,the region will be hotter and wetter,with high flooding potential in the future.These results will be helpful for precise water resources planning and management in this extremely sensitive region to climate change.展开更多
Knowledge of forest management types is key to sustainable forest restoration practices,forest biomass assessment,and carbon accounting.However,there are no available global forest-management maps because of the spect...Knowledge of forest management types is key to sustainable forest restoration practices,forest biomass assessment,and carbon accounting.However,there are no available global forest-management maps because of the spectral similarity of different forest management types.As such,we applied random forest and change detection algorithms to generate annual maps of 6 forest management types at a spatial resolution of 250 m from 2001 to 2020 including naturally regenerated forest(unmanaged and managed),planted forest(rotation of>15 years and≤15 years),oil palm plantation,and agroforestry.In general,validation results on a point scale show that the overall accuracy is 86.82%±9.14%,indicating that our annual maps accurately represent global spatiotemporal variations in forest management types.Furthermore,we estimated the annual biomass carbon stock of different forest management types.The net expanded areas of planted forest,oil palm plantation,and agroforestry offset 59.56%of the loss of forest area and 77.13%of the loss of biomass carbon stock due to the decrease in the naturally regenerated forest.The decrease of managed natural regeneration forests,the expansion of planted forests with a rotation period of more than 15 years,and agroforestry resulted from reforestation practices,while the expansion of planted forests with a rotation period of less than 15 years and oil palm plantations resulted from the removal of part of agroforestry.Moreover,the expansion of planted forests with a rotation of less than 15 years(72.73%)dominates the global expansion of planted forests,and China has contributed 42.20%of this expansion.Our results are beneficial for nature solution-based climate change mitigation.展开更多
基金ssupported by the National Natural Sciences Foundation of China (90302009,40801216)the Ministry of Water Resources' Special Funds for Scientific Research on Public Causes (201001062)
文摘The spatial distribution of vegetation in Qaidam Basin was analyzed using GIMMS（Global Inventory Modeling and Mapping Studies） /NDVI（Normalized Difference Vegetation Index） data set from January 1982 to December 2006.Based on the data of precipitation,terrain,stream systems,land use and the map of vegetation distribution in Qaidam Basin,we studied the factors influencing the spatial distribution of vegetation.The results showed that the vegetation was generally low in Qaidam Basin and there was a clear semi-ring structure from southeast to northwest.In some areas,the existence of rivers,lakes and spring belts turned this semi-ring structure into a non-continuous state and formed distinct bright spots and continuous linear features.There were four main factors that affected the spatial distribution of vegetation coverage in Qaidam Basin,i.e.,precipitation,hydrological conditions,altitude and human activities.Precipitation and altitude have a correlation and determine the basic pattern of vegetation distribution in Qaidam Basin.The impacts of hydrological conditions and human activities were mainly embodied in partial areas,and often broke the pattern of vegetation distribution dominated by precipitation and altitude.
基金financially supported by Qinghai Provincial Natural Science Foundation(2019-ZJ-7020)the Scientific Research and Promotion Projects of the Second Phase Project of Ecological Protection and Construction of the Three Rivers Headwater Region in Qinghai Province(2018-S-3)the Alliance International Sceince Organaizations(ANSO)Collaborative Research Project(ANSO-CR-PP-2022-06).
文摘The Three-River Source Region(TRSR),China's water tower and an important ecological barrier in China,provides a considerable amount of water to the downstream regions,home to more than 500 million people.The present study focused on the assessment of hydrological components(i.e.,precipitation,actual evapotranspiration,potential evapotranspiration,surface flow,baseflow,streamflow,soil moisture,snowmelt water,and terrestrial water storage),their transformation and trends along with meteorological elements(i.e.,maximum temperature,minimum temperature,mean temperature,relative humidity,wind speed,and sunshine hours)in the historical and future periods.For this,the hydrological model,HEC-HMS,was applied to simulate hydrological components and Mann-Kendal to explore the trends for 1981-2015.First time,the statistical downscaling model,SDSM,was used to generate climatic data under the shared socio-economic scenario-5(SSP585)in the region,which was applied to simulate the hydrological cycle.The assessment results showed that precipitation transformed into evapotranspiration and streamflow by 70% and 30%,respectively.In the region,streamflow was generated by 78%,22%,and 5.6% by baseflow,surface flow,and snowmelt.According to trend results,all climatic variables showed statistically significant trends but insignificant in all hydrological components for the historical period,except evapotranspiration.However,all hydroclimatic components were projected to increase in the future,except windspeed.For example,temperature,precipitation,evapotranspiration,streamflow,and direct flow(surface flow)will increase by 1.4(3.3)℃,12(36)%,8.5(19)%,25(95)%,and 77(473)% in 2021-2060(2061-2100)relative to 1981-2020,which shows,the region will be hotter and wetter,with high flooding potential in the future.These results will be helpful for precise water resources planning and management in this extremely sensitive region to climate change.
基金supported by the BNU-FGS Global Environmental Change Program(grant 2023-GC-ZYTS-01)the High-Resolution Earth Observation Major Special Aerial Observation System(grant 30-H30C01-9004-19/21)the State Key Laboratory of Earth Surface Processes and Resource Ecology(grant 2023-KF-02).
文摘Knowledge of forest management types is key to sustainable forest restoration practices,forest biomass assessment,and carbon accounting.However,there are no available global forest-management maps because of the spectral similarity of different forest management types.As such,we applied random forest and change detection algorithms to generate annual maps of 6 forest management types at a spatial resolution of 250 m from 2001 to 2020 including naturally regenerated forest(unmanaged and managed),planted forest(rotation of>15 years and≤15 years),oil palm plantation,and agroforestry.In general,validation results on a point scale show that the overall accuracy is 86.82%±9.14%,indicating that our annual maps accurately represent global spatiotemporal variations in forest management types.Furthermore,we estimated the annual biomass carbon stock of different forest management types.The net expanded areas of planted forest,oil palm plantation,and agroforestry offset 59.56%of the loss of forest area and 77.13%of the loss of biomass carbon stock due to the decrease in the naturally regenerated forest.The decrease of managed natural regeneration forests,the expansion of planted forests with a rotation period of more than 15 years,and agroforestry resulted from reforestation practices,while the expansion of planted forests with a rotation period of less than 15 years and oil palm plantations resulted from the removal of part of agroforestry.Moreover,the expansion of planted forests with a rotation of less than 15 years(72.73%)dominates the global expansion of planted forests,and China has contributed 42.20%of this expansion.Our results are beneficial for nature solution-based climate change mitigation.
