Rice-wheat （R-W） rotation systems are ubiquitous in South and East Asia, and play an important role in modulating the carbon cycle and climate. Long-term, continuous flux measurements help in better understanding th...Rice-wheat （R-W） rotation systems are ubiquitous in South and East Asia, and play an important role in modulating the carbon cycle and climate. Long-term, continuous flux measurements help in better understanding the seasonal and interannual variation of the carbon budget over R-W rotation systems. In this study, measurements of CO2 fluxes and meteorological variables over an R-W rotation system on the North China Plain from 2007 to 2010 were analyzed. To analyze the abiotic factors regulating Net Ecosystem Exchange （NEE）, NEE was partitioned into gross primary production （GPP） and ecosystem respiration. Nighttime NEE or ecosystem respiration was controlled primarily by soil temperature, while daytime NEE was mainly determined by photosythetically active radiation （PAR）. The responses of nighttime NEE to soil temperature and daytime NEE to light were closely associated with crop development and photosynthetic activity, respectively. Moreover, the interannual variation in GPP and NEE mainly depended on precipitation and PAR. Overall, NEE was negative on the annual scale and the rotation system behaved as a carbon sink of 982 g C m 2 per year over the three years. The winter wheat field took up more CO2 than the rice paddy during the longer growing season, while the daily NEE for wheat and rice were -2.35 and -3.96 g C m-2, respectively. After the grain harvest was subtracted from the NEE, the winter wheat field became a moderately strong carbon sink of 251-334 g C m-2 per season, whereas the rice paddy switched to a weak carbon sink of 107-132 per season.展开更多
A 35 year record of production and respiration in the Northern Hemisphere bas been derived from monthly records of atmospheric concentration, fossil fuel combustion, and oceanic absorption of carbon dioxide using a me...A 35 year record of production and respiration in the Northern Hemisphere bas been derived from monthly records of atmospheric concentration, fossil fuel combustion, and oceanic absorption of carbon dioxide using a method developed by Hall et al. The original conclusion of Hall et al. that there was no significant change in biotic metabolism, is confirmed by measuring both production and respiration from 1958 to 1972. But the analysis of the subsequent record shows that both production and respiration have been enhanced since the early 1970s by some large scale global change, probably of human origin. Our results also show that high-latitude regions in the Northern Hemisphere are changing more than regions further south. Nevertheless, the ratio of production to respiration (P/R) remains unchanged during the time period examined. Thus, no argument can be made for net carbon storage of or release from the biosphere from this analysis, although the turnover rate of the biosphere appears to be enhanced.展开更多
The response of plant leaf and root phenology and biomass in the Arctic to global change remains unclear due to the lack of synchronous measurements of above-and belowground parts.Our objective was to determine the ph...The response of plant leaf and root phenology and biomass in the Arctic to global change remains unclear due to the lack of synchronous measurements of above-and belowground parts.Our objective was to determine the phenological dynamics of the above-and belowground parts of Eriophorum vaginatum in the Arctic and its response to warming.We established a common garden located at Toolik Lake Field Station;tussocks of E.vaginatum from three locations,Coldfoot,Toolik Lake and Sagwon,were transplanted into the common garden.Control and warming treatments for E.vaginatum were set up at the Toolik Lake during the growing seasons of 2016 and 2017.Digital cameras,a handheld sensor and minirhizotrons were used to simultaneously observe leaf greenness,normalized difference vegetation index and root length dynamics,respectively.Leaf and root growth rates of E.vaginatum were asynchronous such that the timing of maximal leaf growth(mid-july)was about 28 days earlier than that of root growth.Warming of air temperature by 1°C delayed the timing of leaf senescence and thus prolonged the growing season,but the temperature increase had no significant effect on root phenology.The seasonal dynamics of leaf biomass were affected by air temperature,whereas root biomass was correlated with soil thaw depth.Therefore,we suggest that leaf and root components should be considered comprehensively when using carbon and nutrient cycle models,as above-and belowground productivity and functional traits may have a different response to climate warming.展开更多
The long atmospheric residence time of CO2 creates an urgent need to add atmospheric carbon drawdown to CO2 regulatory strategies.Synthetic and systems biology(SSB),which enables manipulation of cellular phenotypes,of...The long atmospheric residence time of CO2 creates an urgent need to add atmospheric carbon drawdown to CO2 regulatory strategies.Synthetic and systems biology(SSB),which enables manipulation of cellular phenotypes,offers a powerful approach to amplifying and adding new possibilities to current land management practices aimed at reducing atmospheric carbon.The participants(in attendance:Christina Agapakis,George Annas,Adam Arkin,George Church,Robert Cook-Deegan,Charles DeLisi,Dan Drell,Sheldon Glashow,Steve Hamburg,Henry Jacoby,Henry Kelly,Mark Kon,Todd Kuiken,Mary Lidstrom,Mike MacCracken,June Medford,Jerry Melillo,Ron Milo,Pilar Ossorio,Ari Patrinos,Keith Paustian,Kristala Jones Prather,Kent Redford,David Resnik,John Reilly,Richard J.Roberts,Daniel Segre,Susan Solomon,Elizabeth Strychalski,Chris Voigt,Dominic Woolf,Stan Wullschleger,and Xiaohan Yang)identified a range of possibilities by which SSB might help reduce greenhouse gas concentrations and which might also contribute to environmental sustainability and adaptation.These include,among other possibilities,engineering plants to convert CO2 produced by respiration into a stable carbonate,designing plants with an increased root-to-shoot ratio,and creating plants with the ability to self-fertilize.A number of serious ecological and societal challenges must,however,be confronted and resolved before any such application can be fully assessed,realized,and deployed.展开更多
基金supported by the China Meteorological Administration (Grant No.GYHY201006024)the National Key Basic Research Program (Grant Nos.2010CB428502 and 2012CB417203)+2 种基金the Chinese Academy of Sciences Strategic Priority Research Program (Grant No.XDA05110101)the National Natural Science Foundation of China (Grant Nos.40975009 and 41405018)the State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry,Institute of Atmospheric Physics,Chinese Academy of Sciences (Grant No.LAPC-KF-2009-02)
文摘Rice-wheat （R-W） rotation systems are ubiquitous in South and East Asia, and play an important role in modulating the carbon cycle and climate. Long-term, continuous flux measurements help in better understanding the seasonal and interannual variation of the carbon budget over R-W rotation systems. In this study, measurements of CO2 fluxes and meteorological variables over an R-W rotation system on the North China Plain from 2007 to 2010 were analyzed. To analyze the abiotic factors regulating Net Ecosystem Exchange （NEE）, NEE was partitioned into gross primary production （GPP） and ecosystem respiration. Nighttime NEE or ecosystem respiration was controlled primarily by soil temperature, while daytime NEE was mainly determined by photosythetically active radiation （PAR）. The responses of nighttime NEE to soil temperature and daytime NEE to light were closely associated with crop development and photosynthetic activity, respectively. Moreover, the interannual variation in GPP and NEE mainly depended on precipitation and PAR. Overall, NEE was negative on the annual scale and the rotation system behaved as a carbon sink of 982 g C m 2 per year over the three years. The winter wheat field took up more CO2 than the rice paddy during the longer growing season, while the daily NEE for wheat and rice were -2.35 and -3.96 g C m-2, respectively. After the grain harvest was subtracted from the NEE, the winter wheat field became a moderately strong carbon sink of 251-334 g C m-2 per season, whereas the rice paddy switched to a weak carbon sink of 107-132 per season.
文摘A 35 year record of production and respiration in the Northern Hemisphere bas been derived from monthly records of atmospheric concentration, fossil fuel combustion, and oceanic absorption of carbon dioxide using a method developed by Hall et al. The original conclusion of Hall et al. that there was no significant change in biotic metabolism, is confirmed by measuring both production and respiration from 1958 to 1972. But the analysis of the subsequent record shows that both production and respiration have been enhanced since the early 1970s by some large scale global change, probably of human origin. Our results also show that high-latitude regions in the Northern Hemisphere are changing more than regions further south. Nevertheless, the ratio of production to respiration (P/R) remains unchanged during the time period examined. Thus, no argument can be made for net carbon storage of or release from the biosphere from this analysis, although the turnover rate of the biosphere appears to be enhanced.
基金the Office of Polar Programs(National Science Foundation)(1417763 to J.T.,1418010 to N.F.and 1417645 to M.L.M.).
文摘The response of plant leaf and root phenology and biomass in the Arctic to global change remains unclear due to the lack of synchronous measurements of above-and belowground parts.Our objective was to determine the phenological dynamics of the above-and belowground parts of Eriophorum vaginatum in the Arctic and its response to warming.We established a common garden located at Toolik Lake Field Station;tussocks of E.vaginatum from three locations,Coldfoot,Toolik Lake and Sagwon,were transplanted into the common garden.Control and warming treatments for E.vaginatum were set up at the Toolik Lake during the growing seasons of 2016 and 2017.Digital cameras,a handheld sensor and minirhizotrons were used to simultaneously observe leaf greenness,normalized difference vegetation index and root length dynamics,respectively.Leaf and root growth rates of E.vaginatum were asynchronous such that the timing of maximal leaf growth(mid-july)was about 28 days earlier than that of root growth.Warming of air temperature by 1°C delayed the timing of leaf senescence and thus prolonged the growing season,but the temperature increase had no significant effect on root phenology.The seasonal dynamics of leaf biomass were affected by air temperature,whereas root biomass was correlated with soil thaw depth.Therefore,we suggest that leaf and root components should be considered comprehensively when using carbon and nutrient cycle models,as above-and belowground productivity and functional traits may have a different response to climate warming.
基金The workshop was supported by a grant from the Alfred P.Sloan Foundationby the Boston University(BU)Program in Bioinformatics and Systems Biology,and by the BU College of Engineering。
文摘The long atmospheric residence time of CO2 creates an urgent need to add atmospheric carbon drawdown to CO2 regulatory strategies.Synthetic and systems biology(SSB),which enables manipulation of cellular phenotypes,offers a powerful approach to amplifying and adding new possibilities to current land management practices aimed at reducing atmospheric carbon.The participants(in attendance:Christina Agapakis,George Annas,Adam Arkin,George Church,Robert Cook-Deegan,Charles DeLisi,Dan Drell,Sheldon Glashow,Steve Hamburg,Henry Jacoby,Henry Kelly,Mark Kon,Todd Kuiken,Mary Lidstrom,Mike MacCracken,June Medford,Jerry Melillo,Ron Milo,Pilar Ossorio,Ari Patrinos,Keith Paustian,Kristala Jones Prather,Kent Redford,David Resnik,John Reilly,Richard J.Roberts,Daniel Segre,Susan Solomon,Elizabeth Strychalski,Chris Voigt,Dominic Woolf,Stan Wullschleger,and Xiaohan Yang)identified a range of possibilities by which SSB might help reduce greenhouse gas concentrations and which might also contribute to environmental sustainability and adaptation.These include,among other possibilities,engineering plants to convert CO2 produced by respiration into a stable carbonate,designing plants with an increased root-to-shoot ratio,and creating plants with the ability to self-fertilize.A number of serious ecological and societal challenges must,however,be confronted and resolved before any such application can be fully assessed,realized,and deployed.
