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Articles 1 - 27 of 27
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Century-Scale Patterns And Trends Of Global Pyrogenic Carbon Emissions And Fire Influences On Terrestrial Carbon Balance, Jia Yang, Hanqin Tian, Bo Tao, Wei Ren, Chaoqun (Crystal) Lu, Shufen Pan, Yuhang Wang, Yongqiang Liu
Century-Scale Patterns And Trends Of Global Pyrogenic Carbon Emissions And Fire Influences On Terrestrial Carbon Balance, Jia Yang, Hanqin Tian, Bo Tao, Wei Ren, Chaoqun (Crystal) Lu, Shufen Pan, Yuhang Wang, Yongqiang Liu
Chaoqun (Crystal) Lu
Fires have consumed a large amount of terrestrial organic carbon and significantly influenced terrestrial ecosystems and the physical climate system over the past century. Although biomass burning has been widely investigated at a global level in recent decades via satellite observations, less work has been conducted to examine the century-scale changes in global fire regimes and fire influences on the terrestrial carbon balance. In this study, we investigated global pyrogenic carbon emissions and fire influences on the terrestrial carbon fluxes from 1901 to 2010 by using a process-based land ecosystem model. Our results show a significant declining trend in global …
Disentangling Climatic And Anthropogenic Controls On Global Terrestrial Evapotranspiration Trends, Jiafu Mao, Wenting Fu, Xiaoying Shi, Daniel M. Ricciuto, Joshua B. Fisher, Robert E. Dickinson, Yaxing Wei, Willis Shem, Shilong Piao, Kaicun Wang, Christopher R. Schwalm, Hanqin Tian, Mingquan Mu, Altaf Arain, Philippe Ciais, Robert Cook, Yongdiu Dai, Daniel Hayes, Forrest M. Hoffman, Maoyi Huang, Suo Huang, Deborah N. Huntzinger, Akihiko Ito, Atul Jain, Anthony W. King, Huimin Lei, Chaoqun (Crystal) Lu, Huimin Lei, Anna M. Michalak, Changhui Peng, Shushi Peng, Benjamin Poulter, Kevin Schaefer, Elshin Jafarov, Peter E. Thornton, Weile Wang, Ning Zeng, Zhenzhong Zeng, Fang Zhao, Qiuan Zhu, Zaichun Zhu
Disentangling Climatic And Anthropogenic Controls On Global Terrestrial Evapotranspiration Trends, Jiafu Mao, Wenting Fu, Xiaoying Shi, Daniel M. Ricciuto, Joshua B. Fisher, Robert E. Dickinson, Yaxing Wei, Willis Shem, Shilong Piao, Kaicun Wang, Christopher R. Schwalm, Hanqin Tian, Mingquan Mu, Altaf Arain, Philippe Ciais, Robert Cook, Yongdiu Dai, Daniel Hayes, Forrest M. Hoffman, Maoyi Huang, Suo Huang, Deborah N. Huntzinger, Akihiko Ito, Atul Jain, Anthony W. King, Huimin Lei, Chaoqun (Crystal) Lu, Huimin Lei, Anna M. Michalak, Changhui Peng, Shushi Peng, Benjamin Poulter, Kevin Schaefer, Elshin Jafarov, Peter E. Thornton, Weile Wang, Ning Zeng, Zhenzhong Zeng, Fang Zhao, Qiuan Zhu, Zaichun Zhu
Chaoqun (Crystal) Lu
We examined natural and anthropogenic controls on terrestrial evapotranspiration (ET) changes from 1982 to 2010 using multiple estimates from remote sensing-based datasets and process-oriented land surface models.A significant increasing trend of ET in each hemisphere was consistently revealed by observationally-constrained data and multi-model ensembles that considered historic natural and anthropogenic drivers. The climate impacts were simulated to determine the spatiotemporal variations in ET. Globally, risingCO2 ranked second in these models after the predominant climatic influences, and yielded decreasing trends in canopy transpiration and ET, especially for tropical forests and high-latitude shrub land. Increasing nitrogen deposition slightly amplified global ET via …
Climate Extremes Dominating Seasonal And Interannual Variations In Carbon Export From The Mississippi River Basin, Hanqin Tian, Wei Ren, Jia Yang, Bo Tao, Wei-Jun Cai, Steve E. Lohrenz, Charles S. Hopkinson, Mingliang Liu, Qichun Yang, Chaoqun (Crystal) Lu, Bowen Zhang, Kamaljit Banger, Shufen Pan, Ruoying He, Zuo Xue
Climate Extremes Dominating Seasonal And Interannual Variations In Carbon Export From The Mississippi River Basin, Hanqin Tian, Wei Ren, Jia Yang, Bo Tao, Wei-Jun Cai, Steve E. Lohrenz, Charles S. Hopkinson, Mingliang Liu, Qichun Yang, Chaoqun (Crystal) Lu, Bowen Zhang, Kamaljit Banger, Shufen Pan, Ruoying He, Zuo Xue
Chaoqun (Crystal) Lu
Knowledge about the annual and seasonal patterns of organic and inorganic carbon (C) exports from the major rivers of the world to the coastal ocean is essential for our understanding and potential management of the global C budget so as to limit anthropogenic modification of global climate. Unfortunately our predictive understanding of what controls the timing, magnitude, and quality of C export is still rudimentary. Here we use a process-based coupled hydrologic/ecosystem biogeochemistry model (the Dynamic Land Ecosystem Model) to examine how climate variability and extreme events, changing land use, and atmospheric chemistry have affected the annual and seasonal patterns …
Toward “Optimal” Integration Of Terrestrial Biosphere Models, Christopher R. Schwalm, Deborah N. Huntzinger, Joshua B. Fisher, Anna M. Michalak, Kevin Bowman, Philippe Ciais, Robert Cook, Bassil El-Masri, Daniel Hayes, Maoyi Huang, Akihiko Ito, Atul Jain, Anthony W. King, Hiumin Lei, Junjie Liu, Chaoqun (Crystal) Lu, Jaifu Mao, Shushi Peng, Benjamin Poulter, Daniel Ricciuto, Kevin Schaefer, Xiaoying Shi, Bo Tao, Hanqin Tian, Weile Wang, Yaxing Wei, Jia Yang, Ning Zeng
Toward “Optimal” Integration Of Terrestrial Biosphere Models, Christopher R. Schwalm, Deborah N. Huntzinger, Joshua B. Fisher, Anna M. Michalak, Kevin Bowman, Philippe Ciais, Robert Cook, Bassil El-Masri, Daniel Hayes, Maoyi Huang, Akihiko Ito, Atul Jain, Anthony W. King, Hiumin Lei, Junjie Liu, Chaoqun (Crystal) Lu, Jaifu Mao, Shushi Peng, Benjamin Poulter, Daniel Ricciuto, Kevin Schaefer, Xiaoying Shi, Bo Tao, Hanqin Tian, Weile Wang, Yaxing Wei, Jia Yang, Ning Zeng
Chaoqun (Crystal) Lu
Multimodel ensembles (MME) are commonplace in Earth system modeling. Here we perform MME integration using a 10-member ensemble of terrestrial biosphere models (TBMs) from the Multiscale synthesis and Terrestrial Model Intercomparison Project (MsTMIP). We contrast optimal (skill based for present-day carbon cycling) versus naïve (“one model-one vote”) integration. MsTMIP optimal and naïve mean land sink strength estimates (−1.16 versus −1.15 Pg C per annum respectively) are statistically indistinguishable. This holds also for grid cell values and extends to gross uptake, biomass, and net ecosystem productivity. TBM skill is similarly indistinguishable. The added complexity of skill-based integration does not materially change …
Global Patterns And Controls Of Soil Organic Carbon Dynamics As Simulated By Multiple Terrestrial Biosphere Models: Current Status And Future Directions, Hanqin Tian, Chaoqun (Crystal) Lu, Jia Yang, Kamaljit Banger, Denorah N. Huntzinger, Christopher R. Schwalm, Anna M. Michalak, Robert Cook, Philippe Ciais, Daniel Hayes, Maoyi Huang, Akihiko Ito, Atul K. Jain, Huimin Lei, Jiafu Mao, Shufen Pan, Wilfred M. Post, Shushi Peng, Benjamin Poulter, Wei Ren, Daniel Ricciuto, Kevin Schaefer, Xiaoying Shi, Bo Tao, Weile Wang, Yaxing Wei, Qichun Yang, Bowen Zhang, Ning Zeng
Global Patterns And Controls Of Soil Organic Carbon Dynamics As Simulated By Multiple Terrestrial Biosphere Models: Current Status And Future Directions, Hanqin Tian, Chaoqun (Crystal) Lu, Jia Yang, Kamaljit Banger, Denorah N. Huntzinger, Christopher R. Schwalm, Anna M. Michalak, Robert Cook, Philippe Ciais, Daniel Hayes, Maoyi Huang, Akihiko Ito, Atul K. Jain, Huimin Lei, Jiafu Mao, Shufen Pan, Wilfred M. Post, Shushi Peng, Benjamin Poulter, Wei Ren, Daniel Ricciuto, Kevin Schaefer, Xiaoying Shi, Bo Tao, Weile Wang, Yaxing Wei, Qichun Yang, Bowen Zhang, Ning Zeng
Chaoqun (Crystal) Lu
Soil is the largest organic carbon (C) pool of terrestrial ecosystems, and C loss from soil accounts for a large proportion of land-atmosphere C exchange. Therefore, a small change in soil organic C (SOC) can affect atmospheric carbon dioxide (CO2) concentration and climate change. In the past decades, a wide variety of studies have been conducted to quantify global SOC stocks and soil C exchange with the atmosphere through site measurements, inventories, and empirical/process-based modeling. However, these estimates are highly uncertain, and identifying major driving forces controlling soil C dynamics remains a key research challenge. This study has compiled century-long …
Global Methane And Nitrous Oxide Emissions From Terrestrial Ecosystems Due To Multiple Environmental Changes, Hanqin Tian, Guangsheng Chen, Chaoqun (Crystal) Lu, Xiaofeng Xu, Wei Ren, Bowen Zhang, Kamaljit Banger, Bo Tao, Shufen Pan, Mingliang Liu, Chi Zhang, Lori Bruhwiler, Steven Wofsy
Global Methane And Nitrous Oxide Emissions From Terrestrial Ecosystems Due To Multiple Environmental Changes, Hanqin Tian, Guangsheng Chen, Chaoqun (Crystal) Lu, Xiaofeng Xu, Wei Ren, Bowen Zhang, Kamaljit Banger, Bo Tao, Shufen Pan, Mingliang Liu, Chi Zhang, Lori Bruhwiler, Steven Wofsy
Chaoqun (Crystal) Lu
Greenhouse gas (GHG)-induced climate change is among the most pressing sustainability challenges facing humanity today, posing serious risks for ecosystem health. Methane (CH4) and nitrous oxide (N2O) are the two most important GHGs after carbon dioxide (CO2), but their regional and global budgets are not well known. In this study, we applied a process-based coupled biogeochemical model to concurrently estimate the magnitude and spatial and temporal patterns of CH4 and N2O fluxes as driven by multiple environmental changes, including climate variability, rising atmospheric CO2, increasing nitrogen deposition, tropospheric ozone pollution, land use change, and nitrogen fertilizer use. The estimated CH4 …
Responses Of Global Terrestrial Evapotranspiration To Climate Change And Increasing Atmospheric Co2 In The 21st Century, Shufen Pan, Hanqin Tian, Shree R. S. Dangal, Qichun Yang, Jia Yang, Chaoqun (Crystal) Lu, Bo Tao, Wei Ren, Zhiyun Ouyang
Responses Of Global Terrestrial Evapotranspiration To Climate Change And Increasing Atmospheric Co2 In The 21st Century, Shufen Pan, Hanqin Tian, Shree R. S. Dangal, Qichun Yang, Jia Yang, Chaoqun (Crystal) Lu, Bo Tao, Wei Ren, Zhiyun Ouyang
Chaoqun (Crystal) Lu
Quantifying the spatial and temporal patterns of the water lost to the atmosphere through land surface evapotranspiration (ET) is essential for understanding the global hydrological cycle, but remains much uncertain. In this study, we use the Dynamic Land Ecosystem Model to estimate the global terrestrial ET during 2000–2009 and project its changes in response to climate change and increasing atmospheric CO2 under two IPCC SRES scenarios (A2 and B1) during 2010–2099. Modeled results show a mean annual global terrestrial ET of about 549 (545–552) mm yr−1 during 2000–2009. Relative to the 2000s, global terrestrial ET for the 2090s would increase …
Complex Spatiotemporal Responses Of Global Terrestrial Primary Production To Climate Change And Increasing Atmospheric Co2 In The 21st Century, Shufen Pan, Hanqin Tian, Shree R. S. Dangal, Chi Zhang, Jia Yang, Bo Tao, Zhiyun Ouyang, Xiaoke Wang, Chaoqun (Crystal) Lu, Wei Ren, Kamaljit Banger, Qichun Yang, Bowen Zhang, Xia Li
Complex Spatiotemporal Responses Of Global Terrestrial Primary Production To Climate Change And Increasing Atmospheric Co2 In The 21st Century, Shufen Pan, Hanqin Tian, Shree R. S. Dangal, Chi Zhang, Jia Yang, Bo Tao, Zhiyun Ouyang, Xiaoke Wang, Chaoqun (Crystal) Lu, Wei Ren, Kamaljit Banger, Qichun Yang, Bowen Zhang, Xia Li
Chaoqun (Crystal) Lu
Quantitative information on the response of global terrestrial net primary production (NPP) to climate change and increasing atmospheric CO2 is essential for climate change adaptation and mitigation in the 21st century. Using a process-based ecosystem model (the Dynamic Land Ecosystem Model, DLEM), we quantified the magnitude and spatiotemporal variations of contemporary (2000s) global NPP, and projected its potential responses to climate and CO2 changes in the 21st century under the Special Report on Emission Scenarios (SRES) A2 and B1 of Intergovernmental Panel on Climate Change (IPCC). We estimated a global terrestrial NPP of 54.6 (52.8–56.4) PgC yr−1 as a result …
Impact Of Large-Scale Climate Extremes On Biospheric Carbon Fluxes: An Intercomparison Based On Mstmip Data, Jakov Zscheischler, Anna M. Michalak, Christopher Schwalm, Miguel D. Mahecha, Deborah N. Huntzinger, Markus Reichstein, Gwenaëlle Berthier, Philippe Ciais, Robert B. Cook, Bassil El-Masri, Maoyi Huang, Akihiko Ito, Atul Jain, Anthony King, Huimin Lei, Chaoqun (Crystal) Lu, Jiafu Mao, Shushi Peng, Benjamin Poulter, Daniel Ricciuto, Xiaoying Shi, Bo Tao, Hanqin Tian, Nicolas Viovy, Weile Wang, Yaxing Wei, Jia Yang, Ning Zeng
Impact Of Large-Scale Climate Extremes On Biospheric Carbon Fluxes: An Intercomparison Based On Mstmip Data, Jakov Zscheischler, Anna M. Michalak, Christopher Schwalm, Miguel D. Mahecha, Deborah N. Huntzinger, Markus Reichstein, Gwenaëlle Berthier, Philippe Ciais, Robert B. Cook, Bassil El-Masri, Maoyi Huang, Akihiko Ito, Atul Jain, Anthony King, Huimin Lei, Chaoqun (Crystal) Lu, Jiafu Mao, Shushi Peng, Benjamin Poulter, Daniel Ricciuto, Xiaoying Shi, Bo Tao, Hanqin Tian, Nicolas Viovy, Weile Wang, Yaxing Wei, Jia Yang, Ning Zeng
Chaoqun (Crystal) Lu
Understanding the role of climate extremes and their impact on the carbon (C) cycle is increasingly a focus of Earth system science. Climate extremes such as droughts, heat waves, or heavy precipitation events can cause substantial changes in terrestrial C fluxes. On the other hand, extreme changes in C fluxes are often, but not always, driven by extreme climate conditions. Here we present an analysis of how extremes in temperature and precipitation, and extreme changes in terrestrial C fluxes are related to each other in 10 state-of-the-art terrestrial carbon models, all driven by the same climate forcing. We use model …
Climate And Land Use Controls On Soil Organic Carbon In The Loess Plateau Region Of China, Yaai Dang, Wei Ren, Bo Tao, Guangsheng Chen, Chaoqun (Crystal) Lu, Jia Yang, Shufen Pan, Guodong Wang, Shiqing Li, Hanqin Tian
Climate And Land Use Controls On Soil Organic Carbon In The Loess Plateau Region Of China, Yaai Dang, Wei Ren, Bo Tao, Guangsheng Chen, Chaoqun (Crystal) Lu, Jia Yang, Shufen Pan, Guodong Wang, Shiqing Li, Hanqin Tian
Chaoqun (Crystal) Lu
The Loess Plateau of China has the highest soil erosion rate in the world where billion tons of soil is annually washed into Yellow River. In recent decades this region has experienced significant climate change and policy-driven land conversion. However, it has not yet been well investigated how these changes in climate and land use have affected soil organic carbon (SOC) storage on the Loess Plateau. By using the Dynamic Land Ecosystem Model (DLEM), we quantified the effects of climate and land use on SOC storage on the Loess Plateau in the context of multiple environmental factors during the period …
The North American Carbon Program Multi-Scale Synthesis And Terrestrial Model Intercomparison Project – Part 1: Overview And Experimental Design, D. N. Huntzinger, C. Schwalm, A, M, Michalak, K. Schaefer, A. W. King, Y. Wei, A. Jacobson, S. Liu, R. B. Cook, W. M. Post, G. Berthier, D Hayes, M. Huang, A. Ito, H. Lei, Chaoqun (Crystal) Lu, J. Mao, C. H. Peng, S. Peng, B. Poulter, D. Ricciuto, X. Shi, Hanqin Tian, W. Wang, N. Zeng, F. Zhao, Q. Zhu
The North American Carbon Program Multi-Scale Synthesis And Terrestrial Model Intercomparison Project – Part 1: Overview And Experimental Design, D. N. Huntzinger, C. Schwalm, A, M, Michalak, K. Schaefer, A. W. King, Y. Wei, A. Jacobson, S. Liu, R. B. Cook, W. M. Post, G. Berthier, D Hayes, M. Huang, A. Ito, H. Lei, Chaoqun (Crystal) Lu, J. Mao, C. H. Peng, S. Peng, B. Poulter, D. Ricciuto, X. Shi, Hanqin Tian, W. Wang, N. Zeng, F. Zhao, Q. Zhu
Chaoqun (Crystal) Lu
Terrestrial biosphere models (TBMs) have become an integral tool for extrapolating local observations and understanding of land–atmosphere carbon exchange to larger regions. The North American Carbon Program (NACP) Multi-scale synthesis and Terrestrial Model Intercomparison Project (MsTMIP) is a formal model intercomparison and evaluation effort focused on improving the diagnosis and attribution of carbon exchange at regional and global scales. MsTMIP builds upon current and past synthesis activities, and has a unique framework designed to isolate, interpret, and inform understanding of how model structural differences impact estimates of carbon uptake and release. Here we provide an overview of the MsTMIP effort …
Effect Of Continued Nitrogen Enrichment On Greenhouse Gas Emissions From A Wetland Ecosystem In The Sanjiang Plain, Northeast China: A 5 Year Nitrogen Addition Experiment, Changchun Song, Lili Wang, Hanqin Tian, Deyan Liu, Chaoqun (Crystal) Lu, Xiaofeng Xu, Lihua Zhang, Guisheng Yang, Zhongmei Wan
Effect Of Continued Nitrogen Enrichment On Greenhouse Gas Emissions From A Wetland Ecosystem In The Sanjiang Plain, Northeast China: A 5 Year Nitrogen Addition Experiment, Changchun Song, Lili Wang, Hanqin Tian, Deyan Liu, Chaoqun (Crystal) Lu, Xiaofeng Xu, Lihua Zhang, Guisheng Yang, Zhongmei Wan
Chaoqun (Crystal) Lu
Mounting evidence supports that wetland ecosystems, one of the largest carbon pools on the earth, are exposed to ample nitrogen (N) additions due to atmospheric deposition or N loading from upstream agricultural fertilizer application. However, our understanding of how N enrichment affects the fluxes of greenhouse gases (GHGs) in wetlands is weak. A 5 year N addition experiment was conducted to examine the responses of CH4 and N2O fluxes as well as ecosystem respiration from wetlands in the Sanjiang Plain, Northeast China, through 2005 to 2009. Four levels of N addition (control, 0 kg N ha−1 yr−1; low-level, 60 kg …
Effects Of Elevated Carbon Dioxide And Increased Temperature On Methane And Nitrous Oxide Fluxes: Evidence From Field Experiments, Feike A. Dijlstra, Stephen A. Prior, G. Brett Renion, H. Allen Torbert, Hanqin Tian, Chaoqun (Crystal) Lu, Rodney T. Venterea
Effects Of Elevated Carbon Dioxide And Increased Temperature On Methane And Nitrous Oxide Fluxes: Evidence From Field Experiments, Feike A. Dijlstra, Stephen A. Prior, G. Brett Renion, H. Allen Torbert, Hanqin Tian, Chaoqun (Crystal) Lu, Rodney T. Venterea
Chaoqun (Crystal) Lu
Climate change could alter terrestrial ecosystems, which are important sources and sinks of the potent green-house gases (GHGs) nitrous oxide (N2O) and methane (CH4), in ways that either stimulate or decrease the magnitude and duration of global warming. Using manipulative field experiments, we assessed how N2O and CH4 soil fluxes responded to a rise in atmospheric carbon dioxide (CO2) concentration and to increased air temperature. Nitrous oxide and CH4 responses varied greatly among studied ecosystems. Elevated CO2 often stimulated N2O emissions in fertilized systems and CH4 emissions in wetlands, peatlands, and rice paddy fields; both effects were stronger in clayey …
Century-Scale Responses Of Ecosystem Carbon Storage And Flux To Multiple Environmental Changes In The Southern United States, Hanqin Tian, Guangsheng Chen, Chi Zang, Mingliang Liu, Ge Sun, Arthur Chappelka, Wei Ren, Xiaofeng Xu, Chaoqun Lu, Shufen Pan, Hua Chen, Dafeng Hui, Steven Mcnulty, Graeme Lockaby, Eric Vance
Century-Scale Responses Of Ecosystem Carbon Storage And Flux To Multiple Environmental Changes In The Southern United States, Hanqin Tian, Guangsheng Chen, Chi Zang, Mingliang Liu, Ge Sun, Arthur Chappelka, Wei Ren, Xiaofeng Xu, Chaoqun Lu, Shufen Pan, Hua Chen, Dafeng Hui, Steven Mcnulty, Graeme Lockaby, Eric Vance
Chaoqun (Crystal) Lu
Terrestrial ecosystems in the southern United States (SUS) have experienced a complex set of changes in climate, atmospheric CO2 concentration, tropospheric ozone (O3), nitrogen (N) deposition, and land-use and land-cover change (LULCC) during the past century. Although each of these factors has received attention for its alterations on ecosystem carbon (C) dynamics, their combined effects and relative contributions are still not well understood. By using the Dynamic Land Ecosystem Model (DLEM) in combination with spatially explicit, long-term historical data series on multiple environmental factors, we examined the century-scale responses of ecosystem C storage and flux to multiple environmental changes in …
Multifactor Controls On Terrestrial N2o Flux Over North America From 1979 Through 2010, X. F. Xu, Hanqin Tian, G. S. Chen, M. L. Liu, Wei Ren, Chaoqun (Crystal) Lu, C. Zhang
Multifactor Controls On Terrestrial N2o Flux Over North America From 1979 Through 2010, X. F. Xu, Hanqin Tian, G. S. Chen, M. L. Liu, Wei Ren, Chaoqun (Crystal) Lu, C. Zhang
Chaoqun (Crystal) Lu
Nitrous oxide (N2O) is a potent greenhouse gas which also contributes to the depletion of stratospheric ozone (O3). However, the magnitude and underlying mechanisms for the spatiotemporal variations in the terrestrial sources of N2O are still far from certain. Using a process-based ecosystem model (DLEM – the Dynamic Land Ecosystem Model) driven by multiple global change factors, including climate variability, nitrogen (N) deposition, rising atmospheric carbon dioxide (CO2), tropospheric O3 pollution, N fertilizer application, and land conversion, this study examined the spatial and temporal variations in terrestrial N2O flux over North America and further attributed these variations to various driving …
In Situ Phytoplankton Analysis: There’S Plenty Of Room At The Bottom, Jeffrey S. Erickson, Nicole N. Hashemi, James M. Sullivan, Alan D. Weidemann, Frances S. Ligler
In Situ Phytoplankton Analysis: There’S Plenty Of Room At The Bottom, Jeffrey S. Erickson, Nicole N. Hashemi, James M. Sullivan, Alan D. Weidemann, Frances S. Ligler
Nastaran Hashemi
Approximately 70% of the earth is covered with water, within which the most dominant organism is phytoplankton. Not only is phytoplankton at the base of the marine food web, but it also fixes excess carbon dioxide and regulates sulfur on a global scale.1 Changes in phytoplankton populations have been linked to toxicity to humans and marine life, pollution, and global climate change.2 Routine monitoring of both fresh and salt water ecosystems has been taking place formany years, with consortia set up explicitly for this purpose. Consensus indicates that five categories of information are useful for early warning systems.3,4 These are …
Effect Of Nitrogen Deposition On China's Terrestrial Carbon Uptake In The Context Of Multifactor Environmental Changes, Chaoqun (Crystal) Lu, Hanqin Tian, Mingliang Liu, Wei Ren, Xiaofeng Xu, Guangsheng Chen, Chi Zhang
Effect Of Nitrogen Deposition On China's Terrestrial Carbon Uptake In The Context Of Multifactor Environmental Changes, Chaoqun (Crystal) Lu, Hanqin Tian, Mingliang Liu, Wei Ren, Xiaofeng Xu, Guangsheng Chen, Chi Zhang
Chaoqun (Crystal) Lu
The amount of atmospheric nitrogen (N) deposited on the land surface has increased globally and by nearly five times in China from 1901 to 2005. Little is known about how elevated reactive N input has affected the carbon (C) sequestration capability of China's terrestrial ecosystems, largely due to the lack of reliable data on N deposition. Here we have used a newly developed data set of historical N deposition at a spatial resolution of 10 km × 10 km in combination with other gridded historical information on climate, atmospheric composition, land use, and land management practices to drive a process-based …
Contemporary And Projected Biogenic Fluxes Of Methane And Nitrous Oxide In North American Terrestrial Ecosystems, Hanqin Tian, Chaoqun (Crystal) Lu, Guangsheng Chen, Bo Tao, Shufen Pan, Stephen J. Del Grosso, Xiaofeng Xu, Lori Bruhwiler, Steven C. Wofsy, Eric A. Kort, Stephen A. Prior
Contemporary And Projected Biogenic Fluxes Of Methane And Nitrous Oxide In North American Terrestrial Ecosystems, Hanqin Tian, Chaoqun (Crystal) Lu, Guangsheng Chen, Bo Tao, Shufen Pan, Stephen J. Del Grosso, Xiaofeng Xu, Lori Bruhwiler, Steven C. Wofsy, Eric A. Kort, Stephen A. Prior
Chaoqun (Crystal) Lu
Accurately estimating biogenic methane (CH4) and nitrous oxide (N2O) fluxes in terrestrial ecosystems is critical for resolving global budgets of these greenhouse gases (GHGs) and continuing to mitigate climate warming. Here, we assess contemporary biogenic CH4 and N2O budgets and probable climate-change-related impacts on CH4 and N2O emissions in terrestrial North America. Multi-approach estimations show that, during 1990–2010, biogenic CH4 emissions ranged from 0.159 to 0.502 petagrams of carbon dioxide (CO2) equivalents per year (Pg CO2eq yr–1, where 1 Pg = 1 × 1015 g) and N2O emissions ranged from 0.802 to 1.016 Pg CO2eq yr–1, which offset 47–166% of …
Net Exchanges Of Co2, Ch4, And N2o Between China's Terrestrial Ecosystems And The Atmosphere And Their Contributions To Global Climate Warming, Hanqin Tian, Xiaofeng Xu, Chaoqun (Crystal) Lu, Mingliang Liu, Wei Ren, Guangsheng Chen, Jerry Melillo, Jiyuan Liu
Net Exchanges Of Co2, Ch4, And N2o Between China's Terrestrial Ecosystems And The Atmosphere And Their Contributions To Global Climate Warming, Hanqin Tian, Xiaofeng Xu, Chaoqun (Crystal) Lu, Mingliang Liu, Wei Ren, Guangsheng Chen, Jerry Melillo, Jiyuan Liu
Chaoqun (Crystal) Lu
China's terrestrial ecosystems have been recognized as an atmospheric CO2 sink; however, it is uncertain whether this sink can alleviate global warming given the fluxes of CH4 and N2O. In this study, we used a process-based ecosystem model driven by multiple environmental factors to examine the net warming potential resulting from net exchanges of CO2, CH4, and N2O between China's terrestrial ecosystems and the atmosphere during 1961–2005. In the past 45 years, China's terrestrial ecosystems were found to sequestrate CO2 at a rate of 179.3 Tg C yr−1 with a 95% confidence range of (62.0 Tg C yr−1, 264.9 Tg …
Impacts Of Tropospheric Ozone And Climate Change On Net Primary Productivity And Net Carbon Exchange Of China's Forest Ecosystems, Wei Ren, Hanqin Tian, Bo Tao, Arthur Chappelka, Ge Sun, Chaoqun (Crystal) Lu, Mingliang Liu, Guangsheng Chen, Xiaofeng Xu
Impacts Of Tropospheric Ozone And Climate Change On Net Primary Productivity And Net Carbon Exchange Of China's Forest Ecosystems, Wei Ren, Hanqin Tian, Bo Tao, Arthur Chappelka, Ge Sun, Chaoqun (Crystal) Lu, Mingliang Liu, Guangsheng Chen, Xiaofeng Xu
Chaoqun (Crystal) Lu
We investigated how ozone pollution and climate change/variability have interactively affected net primary productivity (NPP) and net carbon exchange (NCE) across China's forest ecosystem in the past half century. Using the dynamic land ecosystem model (DLEM) in conjunction with 10-km-resolution gridded historical data sets (tropospheric O3 concentrations, climate variability/change, and other environmental factors such as land-cover/land-use change (LCLUC), increasing CO2 and nitrogen deposition), we conducted nine simulation experiments to: (1) investigate the temporo-spatial patterns of NPP and NCE in China's forest ecosystems from 1961–2005; and (2) quantify the effects of tropospheric O3 pollution alone or in combination with climate variability …
Climate And Land Use Controls Over Terrestrial Water Use Efficiency In Monsoon Asia, Hanqin Tian, Chaoqun (Crystal) Lu, Guangsheng Chen, Xiaofeng Xu, Mingliang Liu, Wei Ren, Bo Tao, Ge Sun, Shufen Pan, Jiyuan Liu
Climate And Land Use Controls Over Terrestrial Water Use Efficiency In Monsoon Asia, Hanqin Tian, Chaoqun (Crystal) Lu, Guangsheng Chen, Xiaofeng Xu, Mingliang Liu, Wei Ren, Bo Tao, Ge Sun, Shufen Pan, Jiyuan Liu
Chaoqun (Crystal) Lu
Much concern has been raised regarding how and to what extent climate change and intensive human activities have altered water use efficiency (WUE, amount of carbon uptake per unit of water use) in monsoon Asia. By using a process-based ecosystem model [dynamic land ecosystem model (DLEM)], we examined effects of climate change, land use/cover change, and land management practices (i.e. irrigation and nitrogen fertilization) on WUE in terrestrial ecosystems of monsoon Asia during 1948–2000. Our simulations indicated that due to climate variability/change, WUE in the entire area decreased by 3·6% during the study period, with the largest decrease of 6·8% …
Attribution Of Spatial And Temporal Variations In Terrestrial Methane Flux Over North America, X. F. Xu, Hanqin Tian, C. Zhang, M. L. Liu, Wei Ren, G. S. Chen, Chaoqun (Crystal) Lu, L. Bruhwiler
Attribution Of Spatial And Temporal Variations In Terrestrial Methane Flux Over North America, X. F. Xu, Hanqin Tian, C. Zhang, M. L. Liu, Wei Ren, G. S. Chen, Chaoqun (Crystal) Lu, L. Bruhwiler
Chaoqun (Crystal) Lu
The attribution of spatial and temporal variations in terrestrial methane (CH4) flux is essential for assessing and mitigating CH4 emission from terrestrial ecosystems. In this study, we used a process-based model, the Dynamic Land Ecosystem Model (DLEM), in conjunction with spatial data of six major environmental factors to attribute the spatial and temporal variations in the terrestrial methane (CH4) flux over North America from 1979 to 2008 to six individual driving factors and their interaction. Over the past three decades, our simulations indicate that global change factors accumulatively contributed 23.51 ± 9.61 T g CH4-C (1 Tg = 1012 g) …
Spatial And Temporal Patterns Of Ch4 And N2o Fluxes In Terrestrial Ecosystems Of North America During 1979–2008: Application Of A Global Biogeochemistry Model, Hanqin Tian, X. Xu, M. Liu, Wei Ren, C. Zhang, G. Chen, Chaoqun (Crystal) Lu
Spatial And Temporal Patterns Of Ch4 And N2o Fluxes In Terrestrial Ecosystems Of North America During 1979–2008: Application Of A Global Biogeochemistry Model, Hanqin Tian, X. Xu, M. Liu, Wei Ren, C. Zhang, G. Chen, Chaoqun (Crystal) Lu
Chaoqun (Crystal) Lu
Continental-scale estimations of terrestrial methane (CH4) and nitrous oxide (N2O) fluxes over a long time period are crucial to accurately assess the global balance of greenhouse gases and enhance our understanding and prediction of global climate change and terrestrial ecosystem feedbacks. Using a process-based global biogeochemical model, the Dynamic Land Ecosystem Model (DLEM), we quantified simultaneously CH4 and N2O fluxes in North America's terrestrial ecosystems from 1979 to 2008. During the past 30 years, approximately 14.69 ± 1.64 T g C a−1 (1 T g = 1012 g) of CH4, and 1.94 ± 0.1 T g N a−1 of N2O …
全球变化与陆地系统综合集成模拟 ——新一代陆地生态系统动态模型 (Dlem), 汉勤 田, 明亮 刘, 弛 张, 巍 任, 小锋 徐, 广生 陈, 超群 吕, 波 陶
全球变化与陆地系统综合集成模拟 ——新一代陆地生态系统动态模型 (Dlem), 汉勤 田, 明亮 刘, 弛 张, 巍 任, 小锋 徐, 广生 陈, 超群 吕, 波 陶
Chaoqun (Crystal) Lu
人类社会从陆地生态系统获取生产和生活资料的同时也作为一种干扰形式改变着地气之间的动态平衡。这三个既独立又相互耦合的子系统共同组成了一个复杂的陆地系统。如何深入理解这一系统的过程和机制是人类应对气候变化挑战的前提条件。陆地生态系统模型作为一种集成工具，已广泛应用于全球变化研究的各个领域，但从输入数据到模型结构和过程等诸多方面仍存在很大的不确定性。近年来，随着大气和地面生态观测网络的不断完善以及遥感等空间技术的不断强大，使陆地生态系统模型进一步发展和突破成为可能。新一代多因子驱动的陆地生态系统动态模型(Dynamic Land Ecosystem Model, DLEM) 正是在这一背景下 应运而生的。本文旨在介绍DLEM的主体框架、输入输出变量、关键过程、主要功能和特点。
Model Estimates Of Net Primary Productivity, Evapotranspiration, And Water Use Efficiency In The Terrestrial Ecosystems Of The Southern United States During 1895–2007, Hanqin Tian, Guangsheng Chen, Mingliang Liu, Chi Zhang, Ge Sun, Chaoqun (Crystal) Lu, Xiaofeng Xu, Wei Ren, Shufen Pan, Arthur Chappelka
Model Estimates Of Net Primary Productivity, Evapotranspiration, And Water Use Efficiency In The Terrestrial Ecosystems Of The Southern United States During 1895–2007, Hanqin Tian, Guangsheng Chen, Mingliang Liu, Chi Zhang, Ge Sun, Chaoqun (Crystal) Lu, Xiaofeng Xu, Wei Ren, Shufen Pan, Arthur Chappelka
Chaoqun (Crystal) Lu
The effects of global change on ecosystem productivity and water resources in the southern United States (SUS), a traditionally ‘water-rich’ region and the ‘timber basket’ of the country, are not well quantified. We carried out several simulation experiments to quantify ecosystem net primary productivity (NPP), evapotranspiration (ET) and water use efficiency (WUE) (i.e., NPP/ET) in the SUS by employing an integrated process-based ecosystem model (Dynamic Land Ecosystem Model, DLEM). The results indicated that the average ET in the SUS was 710 mm during 1895–2007. As a whole, the annual ET increased and decreased slightly during the first and second half …
Spatial And Temporal Patterns Of Nitrogen Deposition In China: Synthesis Of Observational Data, Chaoqun (Crystal) Lu, Hanqin Tian
Spatial And Temporal Patterns Of Nitrogen Deposition In China: Synthesis Of Observational Data, Chaoqun (Crystal) Lu, Hanqin Tian
Chaoqun (Crystal) Lu
Anthropogenic nitrous pollutant emissions in China significantly increased during the last decades, which contributed to the accelerated nitrogen (N) deposition. In order to characterize spatial pattern of nitrogen deposition, we employed the kriging technique to interpolate sampling data of precipitation chemistry and ambient air concentration from site-network observations over China. The estimation of wet deposition in China was limited to aqueous NO3− and NH4+, while ambient NO2 was the only species involved in the predicted dry deposition fluxes. To obtain wet deposition fluxes, precipitation concentration was multiplied by 20-year mean precipitation amounts with a resolution of 10 × 10 km. …
How Synchronous Are Neogene Marine Plankton Events?, Cinzia Spencer-Cervato, Hans R. Thierstein, David B. Lazarus, Jean-Pierre Beckmann
How Synchronous Are Neogene Marine Plankton Events?, Cinzia Spencer-Cervato, Hans R. Thierstein, David B. Lazarus, Jean-Pierre Beckmann
Cinzia Cervato
An electronic supplement of this material may be obtained on adiskette or Anonymous FTP from KOSMOS.AGU.ORG. (LOGIN toAGU's FTP account using ANONYMOUS as the username andGUEST as the password. Go to the right directory by typing CDAPEND. Type LS to see what files are available. Type GET and thename of the file to get it. Finally, type EXIT to leave the system.)(Paper 94PA01456, How synchronous are Neogene marine planktonevents?, by C. Spencer-Cervato, H. R. Thierstein, D. B. Lazarus, andJ-P Beckmann). Diskette may be ordered from American GeophysicalUnion, 2000 Florida Avenue, N.W., Washington, DC 20009; $15.00.Payment must accompany order. We analyzed …