We propose a theoretical framework for assessing the ecological benefits provided by key national ecological projects in China over the past 20 years.A dataset consisting of six primary indicators and nine secondary i...We propose a theoretical framework for assessing the ecological benefits provided by key national ecological projects in China over the past 20 years.A dataset consisting of six primary indicators and nine secondary indicators of ecosystem structure,ecosystem quality,and ecosystem services for 2000-2019 was generated using ground survey and remote sensing data.Ecological benefits were quantitatively evaluated following the implementation of these projects in China.Areas with medium,relatively high,and high degrees of ecological restoration accounted for 24.1%,11.9%,and 1.7% of the national land,respectively.Degrees of ecological restoration were higher in areas with greater numbers of ecological projects.Areas with relatively and absolutely high degrees of ecological restoration were mainly concentrated in the Loess Plateau,the farming-pastoral zone of northern China,the Northeast China Plain,and an area spanning the borders of Sichuan,Yunnan,Guizhou,Chongqing,and Hunan.The relative contributions of climatic factors and ecological projects to changes in vegetation net primary productivity were 85.4% and 14.6%,respectively,and the relative contributions of climatic factors and ecological projects to changes in water erosion modulus were 69.5% and 30.5%,respectively.The restoration potential of national vegetation coverage was 20%,and the restoration potential percentage of forest and grassland vegetation coverage was 6.4% and 23%,respectively.Climatic conditions can inhibit ecological restoration.Areas with relatively high and high degrees of ecological restoration were mainly distributed in areas with an average annual temperature greater than 0℃ and annual precipitation greater than 300 mm.Therefore,the limitations associated with climate conditions require consideration during the implementation of national ecological projects.The implementation of combined measures should be emphasized,and the benefits of ecological investment funds should be maximized.展开更多
Investigating the spatial and temporal variance in productivity along natural precipitation gradients is one of the most efficient approaches to improve understanding of how ecosystems respond to climate change. In th...Investigating the spatial and temporal variance in productivity along natural precipitation gradients is one of the most efficient approaches to improve understanding of how ecosystems respond to climate change. In this paper, by using the natural precipitation gradient of the Inner Mongolian Plateau from east to west determined by relatively long-term observations, we analyzed the temporal and spatial dynamics of aboveground net primary productivity (ANPP) of the temperate grasslands covering this region. Across this grassland transect, ANPP increased exponentially with the increase of mean annual precipitation (MAP) (ANPP=24.47e0.005MAP, R2=0.48). Values for the three vegetation types desert steppe, typical steppe, and meadow steppe were: 60.86 gm-2a-1, 167.14 gm-2a-1 and 288.73 gm-2a-1 respectively. By contrast, temperature had negative effects on ANPP. The moisture index (K ), which takes into ac- count both precipitation and temperature could explain the spatial variance of ANPP better than MAP alone (ANPP=2020.34K1.24, R2=0.57). Temporally, we found that the inter-annual variation in ANPP (cal- culated as the coefficient of variation, CV) got greater with the increase of aridity. However, this trend was not correlated with the inter-annual variation of precipitation. For all of the three vegetation types, ANPP had greater inter-annual variation than annual precipitation (PPT). Their difference (ANPP CV/PPT CV) was greatest in desert steppe and least in meadow steppe. Our results suggest that in more arid regions, grasslands not only have lower productivity, but also higher inter-annual variation of production. Climate change may have significant effects on the productivity through changes in precipitation pattern, vegetation growth potential, and species diversity.展开更多
The first-stage of an ecological conservation and restoration project in the Three-River Source Region（TRSR）, China, has been in progress for eight years. However, because the ecological effects of this project rema...The first-stage of an ecological conservation and restoration project in the Three-River Source Region（TRSR）, China, has been in progress for eight years. However, because the ecological effects of this project remain unknown, decision making for future project implementation is hindered. Thus, in this study, we developed an index system to evaluate the effects of the ecological restoration project, by integrating field observations, remote sensing, and process-based models. Effects were assessed using trend analyses of ecosystem structures and services. Results showed positive trends in the TRSR since the beginning of the project, but not yet a return to the optima of the 1970 s. Specifically, while continued degradation in grassland has been initially contained, results are still far from the desired objective, ‘grassland coverage increasing by an average of 20%–40%＇. In contrast, wetlands and water bodies have generally been restored, while the water conservation and water supply capacity of watersheds have increased. Indeed, the volume of water conservation achieved in the project meets the objective of a 1.32 billion m^3 increase. The effects of ecological restoration inside project regions was more significant than outside, and, in addition to climate change projects, we concluded that the implementation of ecological conservation and restoration projects has substantially contributed to vegetation restoration. Nevertheless, the degradation of grasslands has not been fundamentally reversed, and to date the project has not prevented increasing soil erosion. In sum, the effects and challenges of this first-stage project highlight the necessity of continuous and long-term ecosystem conservation efforts in this region.展开更多
Foliar and root carbon isotope composition(δ13C) of grassland communities on the Qinghai-Tibet Plateau,China,was obtained by the biomass weighting method and direct measurement.We investigated the characteristics and...Foliar and root carbon isotope composition(δ13C) of grassland communities on the Qinghai-Tibet Plateau,China,was obtained by the biomass weighting method and direct measurement.We investigated the characteristics and altitudinal patterns of foliar and root δ13C and determined which environmental factors influenced foliar δ13 C most.Foliar δ13 C of alpine steppe was significantly higher than that of alpine meadow and temperate steppe.For alpine meadow,root δ13C was significantly higher than of foliar δ13C.Foliar δ13C increased with altitude at an average rate of 0.60‰ km 1 for the whole grassland ecosystem.This rate was lower than that at species level.However,there were no significant relationships between root δ13C and altitude.Atmospheric pressure was a more important factor than temperature and precipitation in its influence on the altitudinal pattern of foliar δ13C at the community level.展开更多
Land surface emissivity is one of the important parameters in temperature inversion from thermal infrared remote sensing. Using MOD11C3 of Terra-MODIS L3 level products, spatio-temporal data sets of land surface emiss...Land surface emissivity is one of the important parameters in temperature inversion from thermal infrared remote sensing. Using MOD11C3 of Terra-MODIS L3 level products, spatio-temporal data sets of land surface emissivity in China for 10 years from 2001 to 2010 are obtained. The results show that the land surface emissivity in the northwest desert region is the lowest in China, with little seasonal variations. In contrast, there are significant seasonal variations in land surface emissivity in northeast China and northern Xinjiang, the Qinghai-Tibet Plateau, the Yangtze River Valley and the eastern and southern China. In winter, the land surface emissivity in the northeast China and northern Xinjiang is relatively high. The land surface emissivity of the Qinghai-Tibet Plateau region is maintained at low value from November to March, while it becomes higher in other months. The land surface emissivity of the Yangtze River Valley, eastern and southern China, and Sichuan Basin varies from July to October, and peaks in August. Land surface emissivity values could be divided into five levels low emissivity （0.6163-0.9638）, moderate-low emissivity （0.9639-0.9709）, moderate emissivity （0.9710-0.9724）, moderate-high emissivity （0.9725-0.9738）, and high emissivity （0.9739-0.9999）. The percentages of areas with low emissivity, moderate-low emissivity and moderate emissivity are, respectively, about 20%, 10% and 20%. The moderate-high emissivity region makes up 40%-50% of China＇s land surface area. The inter-annual variation of moderate-high emissivity region is also very clear, with two peaks （in spring and autumn） and two troughs （in summer and winter）. The inter-annual variation of the high emissivity region is very significant, with a peak in winter （10%）, while only 1% or 2% in other seasons. There is a clear association between the spatio-temporal distribution of China＇s land surface emissivity and temperature： the higher the emissivity, the lower the temperature, and vice versa. Emissivity is an inherent property of any object, but the precise value of its emissivity depends very much on its surrounding environmental factors.展开更多
基金National Key R&D Program of China,No.2017YFC0506501Strategic Priority Research Program of the Chinese Academy of Sciences,No.XDA23100203。
文摘We propose a theoretical framework for assessing the ecological benefits provided by key national ecological projects in China over the past 20 years.A dataset consisting of six primary indicators and nine secondary indicators of ecosystem structure,ecosystem quality,and ecosystem services for 2000-2019 was generated using ground survey and remote sensing data.Ecological benefits were quantitatively evaluated following the implementation of these projects in China.Areas with medium,relatively high,and high degrees of ecological restoration accounted for 24.1%,11.9%,and 1.7% of the national land,respectively.Degrees of ecological restoration were higher in areas with greater numbers of ecological projects.Areas with relatively and absolutely high degrees of ecological restoration were mainly concentrated in the Loess Plateau,the farming-pastoral zone of northern China,the Northeast China Plain,and an area spanning the borders of Sichuan,Yunnan,Guizhou,Chongqing,and Hunan.The relative contributions of climatic factors and ecological projects to changes in vegetation net primary productivity were 85.4% and 14.6%,respectively,and the relative contributions of climatic factors and ecological projects to changes in water erosion modulus were 69.5% and 30.5%,respectively.The restoration potential of national vegetation coverage was 20%,and the restoration potential percentage of forest and grassland vegetation coverage was 6.4% and 23%,respectively.Climatic conditions can inhibit ecological restoration.Areas with relatively high and high degrees of ecological restoration were mainly distributed in areas with an average annual temperature greater than 0℃ and annual precipitation greater than 300 mm.Therefore,the limitations associated with climate conditions require consideration during the implementation of national ecological projects.The implementation of combined measures should be emphasized,and the benefits of ecological investment funds should be maximized.
基金Supported by the National Key Research and Development Program (Grant No. 2002CB412501)the National Natural Science Foundation of China (Grant No. 30590381)
文摘Investigating the spatial and temporal variance in productivity along natural precipitation gradients is one of the most efficient approaches to improve understanding of how ecosystems respond to climate change. In this paper, by using the natural precipitation gradient of the Inner Mongolian Plateau from east to west determined by relatively long-term observations, we analyzed the temporal and spatial dynamics of aboveground net primary productivity (ANPP) of the temperate grasslands covering this region. Across this grassland transect, ANPP increased exponentially with the increase of mean annual precipitation (MAP) (ANPP=24.47e0.005MAP, R2=0.48). Values for the three vegetation types desert steppe, typical steppe, and meadow steppe were: 60.86 gm-2a-1, 167.14 gm-2a-1 and 288.73 gm-2a-1 respectively. By contrast, temperature had negative effects on ANPP. The moisture index (K ), which takes into ac- count both precipitation and temperature could explain the spatial variance of ANPP better than MAP alone (ANPP=2020.34K1.24, R2=0.57). Temporally, we found that the inter-annual variation in ANPP (cal- culated as the coefficient of variation, CV) got greater with the increase of aridity. However, this trend was not correlated with the inter-annual variation of precipitation. For all of the three vegetation types, ANPP had greater inter-annual variation than annual precipitation (PPT). Their difference (ANPP CV/PPT CV) was greatest in desert steppe and least in meadow steppe. Our results suggest that in more arid regions, grasslands not only have lower productivity, but also higher inter-annual variation of production. Climate change may have significant effects on the productivity through changes in precipitation pattern, vegetation growth potential, and species diversity.
基金National Nature Sciences Foundation of China,No.41571504National Key Technology Research and Development Program,No.2013BAC03B00
文摘The first-stage of an ecological conservation and restoration project in the Three-River Source Region（TRSR）, China, has been in progress for eight years. However, because the ecological effects of this project remain unknown, decision making for future project implementation is hindered. Thus, in this study, we developed an index system to evaluate the effects of the ecological restoration project, by integrating field observations, remote sensing, and process-based models. Effects were assessed using trend analyses of ecosystem structures and services. Results showed positive trends in the TRSR since the beginning of the project, but not yet a return to the optima of the 1970 s. Specifically, while continued degradation in grassland has been initially contained, results are still far from the desired objective, ‘grassland coverage increasing by an average of 20%–40%＇. In contrast, wetlands and water bodies have generally been restored, while the water conservation and water supply capacity of watersheds have increased. Indeed, the volume of water conservation achieved in the project meets the objective of a 1.32 billion m^3 increase. The effects of ecological restoration inside project regions was more significant than outside, and, in addition to climate change projects, we concluded that the implementation of ecological conservation and restoration projects has substantially contributed to vegetation restoration. Nevertheless, the degradation of grasslands has not been fundamentally reversed, and to date the project has not prevented increasing soil erosion. In sum, the effects and challenges of this first-stage project highlight the necessity of continuous and long-term ecosystem conservation efforts in this region.
基金supported by National Key Basic Research Program of China (Grant No.2010CB950902)National Natural Science Foundation of China(Grant No.31070427)National High-tech R&D Program of China(Grant No.2009BAC61B01)
文摘Foliar and root carbon isotope composition(δ13C) of grassland communities on the Qinghai-Tibet Plateau,China,was obtained by the biomass weighting method and direct measurement.We investigated the characteristics and altitudinal patterns of foliar and root δ13C and determined which environmental factors influenced foliar δ13 C most.Foliar δ13 C of alpine steppe was significantly higher than that of alpine meadow and temperate steppe.For alpine meadow,root δ13C was significantly higher than of foliar δ13C.Foliar δ13C increased with altitude at an average rate of 0.60‰ km 1 for the whole grassland ecosystem.This rate was lower than that at species level.However,there were no significant relationships between root δ13C and altitude.Atmospheric pressure was a more important factor than temperature and precipitation in its influence on the altitudinal pattern of foliar δ13C at the community level.
基金China Global Change Research Program, No.2010CB950902 National Natural Science Foundation of China, No.41071240
文摘Land surface emissivity is one of the important parameters in temperature inversion from thermal infrared remote sensing. Using MOD11C3 of Terra-MODIS L3 level products, spatio-temporal data sets of land surface emissivity in China for 10 years from 2001 to 2010 are obtained. The results show that the land surface emissivity in the northwest desert region is the lowest in China, with little seasonal variations. In contrast, there are significant seasonal variations in land surface emissivity in northeast China and northern Xinjiang, the Qinghai-Tibet Plateau, the Yangtze River Valley and the eastern and southern China. In winter, the land surface emissivity in the northeast China and northern Xinjiang is relatively high. The land surface emissivity of the Qinghai-Tibet Plateau region is maintained at low value from November to March, while it becomes higher in other months. The land surface emissivity of the Yangtze River Valley, eastern and southern China, and Sichuan Basin varies from July to October, and peaks in August. Land surface emissivity values could be divided into five levels low emissivity （0.6163-0.9638）, moderate-low emissivity （0.9639-0.9709）, moderate emissivity （0.9710-0.9724）, moderate-high emissivity （0.9725-0.9738）, and high emissivity （0.9739-0.9999）. The percentages of areas with low emissivity, moderate-low emissivity and moderate emissivity are, respectively, about 20%, 10% and 20%. The moderate-high emissivity region makes up 40%-50% of China＇s land surface area. The inter-annual variation of moderate-high emissivity region is also very clear, with two peaks （in spring and autumn） and two troughs （in summer and winter）. The inter-annual variation of the high emissivity region is very significant, with a peak in winter （10%）, while only 1% or 2% in other seasons. There is a clear association between the spatio-temporal distribution of China＇s land surface emissivity and temperature： the higher the emissivity, the lower the temperature, and vice versa. Emissivity is an inherent property of any object, but the precise value of its emissivity depends very much on its surrounding environmental factors.
