WorldWideScience

Sample records for net land carbon

  1. Assessing the influence of historic net and gross land changes on the carbon fluxes of Europe.

    Science.gov (United States)

    Fuchs, Richard; Schulp, Catharina J E; Hengeveld, Geerten M; Verburg, Peter H; Clevers, Jan G P W; Schelhaas, Mart-Jan; Herold, Martin

    2016-07-01

    Legacy effects of land cover/use on carbon fluxes require considering both present and past land cover/use change dynamics. To assess past land use dynamics, model-based reconstructions of historic land cover/use are needed. Most historic reconstructions consider only the net area difference between two time steps (net changes) instead of accounting for all area gains and losses (gross changes). Studies about the impact of gross and net land change accounting methods on the carbon balance are still lacking. In this study, we assessed historic changes in carbon in soils for five land cover/use types and of carbon in above-ground biomass of forests. The assessment focused on Europe for the period 1950 to 2010 with decadal time steps at 1-km spatial resolution using a bookkeeping approach. To assess the implications of gross land change data, we also used net land changes for comparison. Main contributors to carbon sequestration between 1950 and 2010 were afforestation and cropland abandonment leading to 14.6 PgC sequestered carbon (of which 7.6 PgC was in forest biomass). Sequestration was highest for old-growth forest areas. A sequestration dip was reached during the 1970s due to changes in forest management practices. Main contributors to carbon emissions were deforestation (1.7 PgC) and stable cropland areas on peaty soils (0.8 PgC). In total, net fluxes summed up to 203 TgC yr(-1) (98 TgC yr(-1) in forest biomass and 105 TgC yr(-1) in soils). For areas that were subject to land changes in both reconstructions (35% of total area), the differences in carbon fluxes were about 68%. Overall for Europe the difference between accounting for either gross or net land changes led to 7% difference (up to 11% per decade) in carbon fluxes with systematically higher fluxes for gross land change data.

  2. Global net land carbon sink: Results from the Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP)

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    Huntzinger, D. N.; Schwalm, C. R.; Michalak, A. M.; Cook, R. B.; Jacobson, A. R.; Schaefer, K. M.; Dasgupta, A.; Poco, J.

    2013-12-01

    The Multi-scale Synthesis and Model Intercomparison Project (MsTMIP) is a formal model intercomparison effort focused on improving the diagnosis and attribution of carbon exchange at regional and global scales. Here we present results from the terrestrial biospheric models participating in the MsTMIP effort, focusing on global and regional model estimates of the net land carbon sink. When compared to estimates of the residual net land sink inferred from atmospheric CO2 observations (i.e., fossil fuel emission + land use land cover change - atmospheric increase - ocean uptake), MsTMIP models predict, on average, a weaker global net land uptake of carbon. There is a large spread in MsTMIP estimates of the net land sink (e.g., -2.5 to 5.0 Pg C/yr in 2010, where a negative flux represents a net release to the atmosphere). Some models consistently show the land surface as a net source of carbon to the atmosphere, which is inconsistent with the atmospheric record. In addition, we examine how model estimates of the cumulative global net sink diverge over the period 1900 to 2010, and the degree to which model sensitivity to forcing factors and fundamental differences in model formulation contribute to this divergence. We link differences in estimates of the cumulative land sink back to each model's sensitivity to key forcing factors including climate variability, CO2 fertilization, nitrogen limitation, and land cover / land-use change. For example, the strength of carbon uptake in most models appears to be strongly coupled with atmospheric CO2 concentrations (CO2 fertilization effect). The strength of this relationship, however, varies across models with some models exhibiting a very strong CO2 fertilization effect (e.g., ORCHIDEE), while others not so (e.g., CLM). To inform the comparison across models, structural differences (i.e., which processes are included and how those processes are parameterized) among the participating models are evaluated using hierarchical

  3. Australian net (1950s-1990) soil organic carbon erosion: implications for CO2 emission and land-atmosphere modelling

    Science.gov (United States)

    Chappell, A.; Webb, N. P.; Viscarra Rossel, R. A.; Bui, E.

    2014-09-01

    The debate remains unresolved about soil erosion substantially offsetting fossil fuel emissions and acting as an important source or sink of CO2. There is little historical land use and management context to this debate, which is central to Australia's recent past of European settlement, agricultural expansion and agriculturally-induced soil erosion. We use "catchment" scale (∼25 km2) estimates of 137Cs-derived net (1950s-1990) soil redistribution of all processes (wind, water and tillage) to calculate the net soil organic carbon (SOC) redistribution across Australia. We approximate the selective removal of SOC at net eroding locations and SOC enrichment of transported sediment and net depositional locations. We map net (1950s-1990) SOC redistribution across Australia and estimate erosion by all processes to be ∼4 Tg SOC yr-1, which represents a loss of ∼2% of the total carbon stock (0-10 cm) of Australia. Assuming this net SOC loss is mineralised, the flux (∼15 Tg CO2-equivalents yr-1) represents an omitted 12% of CO2-equivalent emissions from all carbon pools in Australia. Although a small source of uncertainty in the Australian carbon budget, the mass flux interacts with energy and water fluxes, and its omission from land surface models likely creates more uncertainty than has been previously recognised.

  4. Net Ecosystem Carbon Flux

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Net Ecosystem Carbon Flux is defined as the year-over-year change in Total Ecosystem Carbon Stock, or the net rate of carbon exchange between an ecosystem and the...

  5. BECCS capability of dedicated bioenergy crops under a future land-use scenario targeting net negative carbon emissions

    Science.gov (United States)

    Kato, E.; Yamagata, Y.

    2014-12-01

    Bioenergy with Carbon Capture and Storage (BECCS) is a key component of mitigation strategies in future socio-economic scenarios that aim to keep mean global temperature rise below 2°C above pre-industrial, which would require net negative carbon emissions in the end of the 21st century. Because of the additional need for land, developing sustainable low-carbon scenarios requires careful consideration of the land-use implications of deploying large-scale BECCS. We evaluated the feasibility of the large-scale BECCS in RCP2.6, which is a scenario with net negative emissions aiming to keep the 2°C temperature target, with a top-down analysis of required yields and a bottom-up evaluation of BECCS potential using a process-based global crop model. Land-use change carbon emissions related to the land expansion were examined using a global terrestrial biogeochemical cycle model. Our analysis reveals that first-generation bioenergy crops would not meet the required BECCS of the RCP2.6 scenario even with a high fertilizer and irrigation application. Using second-generation bioenergy crops can marginally fulfill the required BECCS only if a technology of full post-process combustion CO2 capture is deployed with a high fertilizer application in the crop production. If such an assumed technological improvement does not occur in the future, more than doubling the area for bioenergy production for BECCS around 2050 assumed in RCP2.6 would be required, however, such scenarios implicitly induce large-scale land-use changes that would cancel half of the assumed CO2 sequestration by BECCS. Otherwise a conflict of land-use with food production is inevitable.

  6. Comparing the influence of net and gross anthropogenic land-use and land-cover changes on the carbon cycle in the MPI-ESM

    Directory of Open Access Journals (Sweden)

    S. Wilkenskjeld

    2014-09-01

    Full Text Available Global vegetation models traditionally treat anthropogenic land-use and land-cover changes (LULCCs only as the changes in vegetation cover seen from one year to the next (net transitions. This approach ignores subgrid-scale processes such as shifting cultivation which do not affect the net vegetation distribution but which have an impact on the carbon budget. The differences in the carbon stocks feed back on processes like wildfires and desert formation. The simulations for the Coupled Model Intercomparison Project Phase 5 (CMIP5 all describe LULCCs using the "Land-Use Harmonization Dataset". Though this dataset describes such subgrid-scale processes (gross transitions, some of the CMIP5 models still use the traditional approach. Using JSBACH/CBALANCE – the land carbon component of the Max Planck Institute Earth System Model (MPI-ESM, this study demonstrates how this potentially leads to a severe underestimation of the carbon emissions from LULCCs Using net transitions lowers the average land-use emissions from 1.44 to 0.90 Pg C yr−1 (38% during the historical period (1850–2005 – a total lowering by 85 Pg C. The difference between the methods is smaller in the RCP scenarios (2006–2100 but in RCP2.6 and RCP8.5 still cumulates to 30–40 Pg C (on average 0.3–0.4 Pg C yr−1 or 13–25%. In RCP4.5 essentially no difference between the methods is found. Results from models using net transitions are furthermore found to be sensitive to model resolution.

  7. Carbon and nitrogen tracers of land use effects on net ecosystem metabolism in mangrove estuaries, southwest Florida

    Science.gov (United States)

    Dvorak, Matthew; Mora, Germán; Graniero, Lauren; Surge, Donna

    2016-11-01

    Four estuaries in southwest Florida with different land-use characteristics in their watersheds were chosen to investigate the effects of anthropogenic land use on estuarine biogeochemical cycling. We compared C:N ratios, concentrations of dissolved inorganic carbon (DIC), chlorophyll-a (chl-a) and particulate organic carbon (POC), stable isotope ratios of DIC (δ13CDIC) and POC (δ13CPOC), and nitrogen isotope ratios of particulate organic nitrogen (δ15NPON) among these estuaries. Values of δ13CDIC ranged from -14.1 to +0.9‰. The more negative values occurred upstream, resulting from DIC inputs derived from both the degradation of organic carbon and dissolution of carbonates. Upstream DIC concentrations were as high as 8066 μmol L-1, suggesting high respiration rates. Further, a comparison of DIC values to a conservative mixing model indicates net heterotrophic metabolic state in all four estuaries. Supporting this interpretation, low δ13CPOC values suggest that terrestrial plants were the main source of POC in the upstream sampling points. However, C:N ratios ranged from 7.2 to 13.4, and were consistent with the decomposition of both terrestrial and aquatic sources. Chl-a concentrations were variable and typically below 20 μg L-1, indicating moderate to low levels of autotrophy in all estuaries. Elevated chl-a concentrations indicative of increased primary productivity occurred at intermediate salinities, and were possibly caused by the mixing front at mid-estuary locations. There were no apparent differences in δ15NPON among estuaries, suggesting that the N sources to these estuaries are comparable. The combined results show no differences between near-natural and anthropogenically influenced estuaries, indicating a minimal effect of anthropogenic activities on the parameters measured, possibly as a result of the filtering capacity of the extensive surrounding mangrove vegetation.

  8. RESOLUTION AND ERROR IN MEASURING LAND-COVER CHANGE: EFFECTS ON ESTIMATING NET CARBON RELEASE FROM MEXICAN TERRESTRIAL ECOSYSTEMS

    Science.gov (United States)

    Reliable estimates of carbon exchange between terrestrial ecosystems and the atmosphere due to land-use change have become increasingly important. One source of land-use changes estimates comes from comparing multi-date remote sensing imagery, though the effect of land-cover clas...

  9. Net land-atmosphere flows of biogenic carbon related to bioenergy: towards an understanding of systemic feedbacks.

    Science.gov (United States)

    Haberl, Helmut

    2013-07-01

    The notion that biomass combustion is carbon neutral vis-a-vis the atmosphere because carbon released during biomass combustion is absorbed during plant regrowth is inherent in the greenhouse gas accounting rules in many regulations and conventions. But this 'carbon neutrality' assumption of bioenergy is an oversimplification that can result in major flaws in emission accounting; it may even result in policies that increase, instead of reduce, overall greenhouse gas emissions. This commentary discusses the systemic feedbacks and ecosystem succession/land-use history issues ignored by the carbon neutrality assumption. Based on recent literature, three cases are elaborated which show that the C balance of bioenergy may range from highly beneficial to strongly detrimental, depending on the plants grown, the land used (including its land-use history) as well as the fossil energy replaced. The article concludes by proposing the concept of GHG cost curves of bioenergy as a means for optimizing the climate benefits of bioenergy policies.

  10. Uncovering the Minor Contribution of Land-Cover Change in Upland Forests to the Net Carbon Footprint of a Boreal Hydroelectric Reservoir.

    Science.gov (United States)

    Dessureault, Pierre-Luc; Boucher, Jean-François; Tremblay, Pascal; Bouchard, Sylvie; Villeneuve, Claude

    2015-07-01

    Hydropower in boreal conditions is generally considered the energy source emitting the least greenhouse gas per kilowatt-hour during its life cycle. The purpose of this study was to assess the relative contribution of the land-use change on the modification of the carbon sinks and sources following the flooding of upland forested territories to create the Eastmain-1 hydroelectric reservoir in Quebec's boreal forest using Carbon Budget Model of the Canadian Forest Sector. Results suggest a carbon sink loss after 100 yr of 300,000 ± 100,000 Mg CO equivalents (COe). A wildfire sensitivity analysis revealed that the ecosystem would have acted as a carbon sink as long as forests to the total net carbon footprint of a hydroelectric reservoir in the boreal zone can be. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  11. Net ecosystem exchange from five land-use transitions to bioenergy crops from four locations across the UK - The Ecosystem Land Use Modelling & Soil Carbon GHG Flux Trial (ELUM) project.

    Science.gov (United States)

    Xenakis, Georgios; Perks, Mike; Harris, Zoe M.; McCalmont, Jon; Rylett, Daniel; Brooks, Milo; Evans, Jonathan G.; Finch, Jon; Rowe, Rebecca; Morrison, Ross; Alberti, Giorgio; Donnison, Ian; Siebicke, Lukas; Morison, James; Taylor, Gail; McNamara, Niall P.

    2016-04-01

    A major part of international agreements on combating climate change is the conversion from a fossil fuel economy to a low carbon economy. Bioenergy crops have been proposed as a way to improve energy security while reducing CO2 emissions to help mitigate the effects of climate change. However, the impact of land-use change from a traditional land use (e.g., arable and grassland) to bioenergy cropping systems on greenhouse gas balance (GHG) and carbon stocks are poorly quantified at this time. The Ecosystem Land Use Modelling & Soil Carbon GHG Flux Trial (ELUM) project was commissioned and funded by the Energy Technologies Institute (ETI) to provide scientific evidence within the UK on a range of land-use conversions (LUC) to bioenergy crops. The ELUM network consists of seven partners investigating five LUCs in four locations including Scotland, Wales, North and South England. Transitions included grasslands to short rotation forestry (SRF), to short rotation coppice willow (SRC) and to Miscanthus and arable to SRC and Miscanthus Measurements of net ecosystem exchange (NEE) along with continuous measurements of meteorological conditions were made at seven sub-sites over a two-year period. Results showed that, over two years, two of the land-uses, a grassland in South England and a grassland conversion to Miscanthus in Wales were net sources of carbon. The greatest carbon sink was into the SRF site in Scotland followed by the SRC willow in South England. The annual terrestrial ecosystem respiration (TER) for the SRC willow in North and South Sussex sites were similar, but the annual GPP at the South England site was about 27% higher than that the North England site. Establishing a long term network will allow us to continue monitoring the effects of land use change on whole ecosystem carbon balance, providing an insight into which types of LUC are suitable for bioenergy cropping in the UK.

  12. Net Carbon Balance for the Brazilian Amazon

    Science.gov (United States)

    Houghton, R. A.

    1998-01-01

    The general purpose of this research was to use recent satellite-based estimates of deforestation in Brazilian Amazonia to calculate the net flux of carbon associated with deforestation and subsequent regrowth of secondary forests. We have made such a calculation, in the process comparing two estimates of deforestation and two estimates of biomass for the region. Both estimates were based on the RADAMBRASIL survey. They differed in the equations used to convert wood-volumes to total biomass. The net flux of carbon from changes in land use seems to vary from year to year, perhaps by as much as a factor of 4.

  13. Australian net (1950s-1990) soil organic carbon erosion: implications for CO2 emission and land-atmosphere modelling

    Science.gov (United States)

    The debate remains unresolved about soil erosion substantially offsetting fossil fuel emissions and acting as an important source or sink of CO2. There is little historical land use and management context to this debate, which is central to Australia's recent past of European settlement, agricultura...

  14. Dissolved carbon leaching from soil is a crucial component of the net ecosystem carbon balance

    NARCIS (Netherlands)

    Kindler, R.; Siemens, J.; Kaiser, K.; Moors, E.J.

    2011-01-01

    Estimates of carbon leaching losses from different land use systems are few and their contribution to the net ecosystem carbon balance is uncertain. We investigated leaching of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and dissolved methane (CH4), at forests, grasslands, and

  15. Net Ecosystem Exchange and Net Biome Productivity of different land use in eastern Germany

    Science.gov (United States)

    Grünwald, Thomas; Prescher, Anne-Katrin; Bernhofer, Christian

    2010-05-01

    The carbon (CO2-C) budgets of a managed forest (spruce), grassland and a cropland (crop rotation) have been determined and compared. The sites are part of the Tharandt cluster which features low intersite variability in climate due to the small distances between the sites. This allows the comparison of management effects on the carbon budget of different land use among other things. At the forest site, continuous CO2 flux measurements are available from 1997 to 2008, the common observation period of the grassland and cropland sites was 2005 to 2008. With regard to annual net ecosystem exchange NEE (based on eddy covariance flux measurements), the forest showed the highest net sink (-698 g C m-2 (1999) to -444 g C m-2 (2003)). In contrast the grassland and cropland sites were significantly lower sinks in terms of NEE (-177 g C m-2 (2004) to -62 g C m-2 (2005) and -115 g C m-2 (2005) to -32 g C m-2 (2007 and 2008), respectively). To quantify the net biome productivity (NBP) carbon exports due to thinning or harvest as well as carbon imports due to organic fertilisation are considered besides NEE. Carbon exports and imports change the carbon budget in terms of NBP. At the forest site only the 2002 NBP is a carbon source (+221 g C m-2) due to the thinning in April 2002 when around 43 m3 ha-1 solid wood was removed from the ecosystem. After the thinning the annual NEE is reduced by around 100 g C m-2 until 2007. The grassland NBP alternated between carbon source and sink (+25 g C m-2 (2008) to -28 g C m-2 (2006)) indicating the carbon balance was approximately neutral. Low NEE and NBP values at the grassland site were a consequence of carbon export due to several cuts per year. The NBP of the cropland ecosystem was mainly influenced by the crop type (winter or spring crop) and the application of organic fertiliser (manure) resulting in carbon budgets between +484 g C m-2 (2007) and -89 g C m-2 (2006). The different timing and length of the growing season of winter and

  16. Carbon emissions from land use and land-cover change

    Directory of Open Access Journals (Sweden)

    R. A. Houghton

    2012-12-01

    Full Text Available The net flux of carbon from land use and land-cover change (LULCC accounted for 12.5% of anthropogenic carbon emissions from 1990 to 2010. This net flux is the most uncertain term in the global carbon budget, not only because of uncertainties in rates of deforestation and forestation, but also because of uncertainties in the carbon density of the lands actually undergoing change. Furthermore, there are differences in approaches used to determine the flux that introduce variability into estimates in ways that are difficult to evaluate, and not all analyses consider the same types of management activities. Thirteen recent estimates of net carbon emissions from LULCC are summarized here. In addition to deforestation, all analyses considered changes in the area of agricultural lands (croplands and pastures. Some considered, also, forest management (wood harvest, shifting cultivation. None included emissions from the degradation of tropical peatlands. Means and standard deviations across the thirteen model estimates of annual emissions for the 1980s and 1990s, respectively, are 1.14 ± 0.23 and 1.12 ± 0.25 Pg C yr−1 (1 Pg = 1015 g carbon. Four studies also considered the period 2000–2009, and the mean and standard deviations across these four for the three decades are 1.14 ± 0.39, 1.17 ± 0.32, and 1.10 ± 0.11 Pg C yr−1. For the period 1990–2009 the mean global emissions from LULCC are 1.14 ± 0.18 Pg C yr−1. The standard deviations across model means shown here are smaller than previous estimates of uncertainty as they do not account for the errors that result from data uncertainty and from an incomplete understanding of all the processes affecting the net flux of carbon from LULCC. Although these errors have not been systematically evaluated, based on partial analyses available in the literature and expert opinion, they are estimated to be on the order of ± 0.5 Pg C yr−1.

  17. Carbon balance of Russian agricultural land

    Science.gov (United States)

    Schepaschenko, D.; Shvidenko, A.; Schepaschenko, M.

    2012-04-01

    Russia managed 218.7 mln ha agricultural land (2009) in accordance with national statistics (FSSS, 2011: http://www.gks.ru/dbscripts/Cbsd/DBInet.cgi#1). Among that, 91.75 mln ha is arable land; 92.05 mln ha - hayfield and pasture; 34.9 mln ha - abandoned arable and fallow. Abandoned arable area is not indicated directly in the statistics, but can be calculated as a difference between "arable" and "cultivated" area. We estimated carbon balance of agricultural land by accounting carbon fluxes. Carbon sink includes: net primary productivity (NPP), applying fertilizes and liming. Carbon losses include soil respiration (SR), harvest and lateral flux. The initial data (cultivated area and harvest distribution by regions and crop) was derived from national agriculture statistics (FSSS, 2011). NPP was estimated via harvest and set of regression models. Average NPP for agricultural land was estimated at 435 g C m-2 (530 g C m-2 for crops). Soil respiration was calculated by a model (Mukhortova et. al., 1011: http://www.iiasa.ac.at/Research/FOR/forest_cdrom/Articles/Mukhortova_2011_IBFRA_SR.pdf) developed for Russia which is based on all available empirical data and accounted for climatic parameters, soil type and management practice. Average SR of agricultural land is 344 g C m-2 (372 g C m-2 for the cropland). We applied the IPCC method (National inventory, 2010; IPCC, 2006) for fertilizer and lateral fluxes assessment. The total carbon balance of agricultural land is almost in equilibrium (-0.04 t C ha-1) in spite of arable land is a carbon source (-0.84 t C ha-1). The highest sink (1.21 t C ha-1) is provided by abandoned land. Carbon fluxes vary substantially depending on seasonal weather conditions. For example grains' NPP in 2010 (dry and hot summer in major agricultural regions of European Russia) was estimated at 32% less compare to 2009 and the total carbon balance of this land category decreased by order of magnitude. We used Russian land cover (Schepaschenko et al

  18. Land use change and net C flux in Indian forests

    NARCIS (Netherlands)

    Kaul, M.; Dadhwal, V.K.; Mohren, G.M.J.

    2009-01-01

    This paper reports on the net carbon flux caused by deforestation and afforestation in India over the period from 1982 to 2002, separately for two time periods, 1982¿1992 (PI) and 1992¿2002 (PII), using the IPCC 2006 guidelines for greenhouse gas inventories. The approach accounts for forest and soi

  19. Drivers and patterns of land biosphere carbon balance reversal

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    Müller, Christoph; Stehfest, Elke; van Minnen, Jelle G.; Strengers, Bart; von Bloh, Werner; Beusen, Arthur H. W.; Schaphoff, Sibyll; Kram, Tom; Lucht, Wolfgang

    2016-04-01

    The carbon balance of the land biosphere is the result of complex interactions between land, atmosphere and oceans, including climatic change, carbon dioxide fertilization and land-use change. While the land biosphere currently absorbs carbon dioxide from the atmosphere, this carbon balance might be reversed under climate and land-use change (‘carbon balance reversal’). A carbon balance reversal would render climate mitigation much more difficult, as net negative emissions would be needed to even stabilize atmospheric carbon dioxide concentrations. We investigate the robustness of the land biosphere carbon sink under different socio-economic pathways by systematically varying climate sensitivity, spatial patterns of climate change and resulting land-use changes. For this, we employ a modelling framework designed to account for all relevant feedback mechanisms by coupling the integrated assessment model IMAGE with the process-based dynamic vegetation, hydrology and crop growth model LPJmL. We find that carbon balance reversal can occur under a broad range of forcings and is connected to changes in tree cover and soil carbon mainly in northern latitudes. These changes are largely a consequence of vegetation responses to varying climate and only partially of land-use change and the rate of climate change. Spatial patterns of climate change as deduced from different climate models, substantially determine how much pressure in terms of global warming and land-use change the land biosphere will tolerate before the carbon balance is reversed. A reversal of the land biosphere carbon balance can occur as early as 2030, although at very low probability, and should be considered in the design of so-called peak-and-decline strategies.

  20. Australian net (1950s-1990) soil organic carbon erosion is an omitted CO2 source

    Science.gov (United States)

    Chappell, A.; Webb, N.; Viscarra Rossel, R. A.; Bui, E. N.

    2013-12-01

    The debate about agricultural erosion substantially offsetting fossil fuel emissions and acting as an important source or sink of CO2 is informed by studies of water and tillage erosion at the field scale and extrapolated across regions based on gross erosion. We use ';catchment' scale (~25 km2) estimates of 137Cs-derived net (1950s-1990) soil redistribution of all processes (wind, water and tillage) to calculate the soil organic carbon (SOC) net redistribution across Australia. We include the selective removal of SOC at net eroding locations, SOC enrichment of transported sediment and net depositional locations. We show that the total SOC net redistribution for Australia is -4.06 Tg SOC y-1, a net loss of SOC from the terrestrial ecosystem and 2% of the total carbon stock (0-10 cm) of Australia. Assuming the SOC is mineralised, these losses represent 12% of CO2-e emissions from all carbon pools in Australia and a significant source of uncertainty in the carbon budget SOC net redistribution as a proportion (%) of SOC stocks Calculation of soil organic carbon net (1950s-1990) redistribution and its proportion for land use classes across Australia *Using an equal area projection the area of a pixel is approximately 4.53 km x 4.87 km ≈ 22.03 km2 equivalent to 2203 ha

  1. The Role of Anode Manufacturing Processes in Net Carbon Consumption

    Directory of Open Access Journals (Sweden)

    Khalil Khaji

    2016-05-01

    Full Text Available Carbon anodes are consumed in electrolysis cells during aluminum production. Carbon consumption in pre-bake anode cells is 400–450 kg C/t Al, considerably higher than the theoretical consumption of 334 kg C/t Al. This excess carbon consumption is partly due to the anode manufacturing processes. Net carbon consumption over the last three years at Emirates Aluminium (EMAL, also known as Emirates Global Aluminium (EGA Al Taweelah was analyzed with respect to anode manufacturing processes/parameters. The analysis indicates a relationship between net carbon consumption and many manufacturing processes, including anode desulfurization during anode baking. Anode desulfurization appears to increase the reaction surface area, thereby helping the Boudouard reaction between carbon and carbon dioxide in the electrolysis zone, as well as reducing the presence of sulfur which could inhibit this reaction. This paper presents correlations noted between anode manufacturing parameters and baked anode properties, and their impact on the net carbon consumption in electrolytic pots. Anode reactivities affect the carbon consumption in the pots during the electrolysis of alumina. Pitch content in anodes, impurities in anodes, and anode desulfurization during baking were studied to find their influence on anode reactivities. The understanding gained through this analysis helped reduce net carbon consumption by adjusting manufacturing processes. For an aluminum smelter producing one million tonnes of aluminum per year, the annual savings could be as much as US $0.45 million for every kg reduction in net carbon consumption.

  2. The effect of land-use change on the net exchange rates of greenhouse gases: a meta-analytical approach

    Directory of Open Access Journals (Sweden)

    D.-G. Kim

    2014-01-01

    Full Text Available One of the environmental impacts of land-use change (LUC is a change in the net exchange of the greenhouse gases (GHGs carbon dioxide (CO2, methane (CH4 and nitrous oxide (N2O. Here we summarize findings based on a new global database containing data sets of changes in soil organic carbon stocks and soil CH4 and N2O fluxes. We combine that with estimates of biomass carbon stock changes and enteric CH4 emissions following LUC. Data were expressed in common units by converting net CH4 and N2O fluxes to CO2 equivalents (CO2 eq using established global warming potentials, and carbon-stock changes were converted to annual net fluxes by averaging stock changes over 100 yr. Conversion from natural forest to cropland resulted in the greatest increase in net GHG fluxes, while conversion of cropland to secondary forest resulted in the greatest reduction in net GHG emissions. Specifically, LUC from natural forest to crop and grasslands led to net fluxes of 6.2 ± 1.6 (Mean ± 95% confidence intervals and 4.8 ± 1.6 t CO2 eq ha−1 yr−1 to the atmosphere, respectively. Conversely, conversion from crop and grasslands to secondary forest reduced net emissions by 6.1 ± 4.1 and 3.9 ± 1.2 t CO2 eq ha−1 yr−1, respectively. Land-use change impacts were generally dominated by changes in biomass carbon. A retrospective analysis indicated that LUC from natural forests to agricultural lands contributed a cumulative 1326 ± 449 Gt CO2 eq between 1765 and 2005, which is equivalent to average emissions of 5.5 ± 1.6 Gt CO2 eq yr−1. This study demonstrates how specific LUCs can positively or negatively affect net GHG fluxes to the atmosphere.

  3. Dissolved carbon leaching from soil is a crucial component of the net ecosystem carbon balance

    DEFF Research Database (Denmark)

    Kindler, Reimo; Siemens, Jan; Kaiser, Klaus;

    2011-01-01

    Estimates of carbon leaching losses from different land use systems are few and their contribution to the net ecosystem carbon balance is uncertain. We investigated leaching of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and dissolved methane (CH4), at forests, grasslands......, and croplands across Europe. Biogenic contributions to DIC were estimated by means of its d13C signature. Leaching of biogenic DIC was 8.34.9 gm2 yr1 for forests, 24.17.2 gm2 yr1 for grasslands, and 14.64.8 gm2 yr1 for croplands. DOC leaching equalled 3.51.3 gm2 yr1 for forests, 5.32.0 gm2 yr1 for grasslands...... (hydr)oxides. Partial pressures of CO2 in soil air and soil pH determined DIC concentrations and fluxes, but soil solutions were often supersaturated with DIC relative to soil air CO2. Leaching losses of biogenic carbon (DOC plus biogenic DIC) from grasslands equalled 5–98% (median: 22%) of net...

  4. Net carbon flux in organic and conventional olive production systems

    Science.gov (United States)

    Saeid Mohamad, Ramez; Verrastro, Vincenzo; Bitar, Lina Al; Roma, Rocco; Moretti, Michele; Chami, Ziad Al

    2014-05-01

    Agricultural systems are considered as one of the most relevant sources of atmospheric carbon. However, agriculture has the potentiality to mitigate carbon dioxide mainly through soil carbon sequestration. Some agricultural practices, particularly fertilization and soil management, can play a dual role in the agricultural systems regarding the carbon cycle contributing to the emissions and to the sequestration process in the soil. Good soil and input managements affect positively Soil Organic Carbon (SOC) changes and consequently the carbon cycle. The present study aimed at comparing the carbon footprint of organic and conventional olive systems and to link it to the efficiency of both systems on carbon sequestration by calculating the net carbon flux. Data were collected at farm level through a specific and detailed questionnaire based on one hectare as a functional unit and a system boundary limited to olive production. Using LCA databases particularly ecoinvent one, IPCC GWP 100a impact assessment method was used to calculate carbon emissions from agricultural practices of both systems. Soil organic carbon has been measured, at 0-30 cm depth, based on soil analyses done at the IAMB laboratory and based on reference value of SOC, the annual change of SOC has been calculated. Substracting sequestrated carbon in the soil from the emitted on resulted in net carbon flux calculation. Results showed higher environmental impact of the organic system on Global Warming Potential (1.07 t CO2 eq. yr-1) comparing to 0.76 t CO2 eq. yr-1 in the conventional system due to the higher GHG emissions caused by manure fertilizers compared to the use of synthetic foliar fertilizers in the conventional system. However, manure was the main reason behind the higher SOC content and sequestration in the organic system. As a resultant, the organic system showed higher net carbon flux (-1.7 t C ha-1 yr-1 than -0.52 t C ha-1 yr-1 in the conventional system reflecting higher efficiency as a

  5. Global and regional fluxes of carbon from land use and land cover change 1850-2015

    Science.gov (United States)

    Houghton, R. A.; Nassikas, Alexander A.

    2017-03-01

    The net flux of carbon from land use and land cover change (LULCC) is an important term in the global carbon balance. Here we report a new estimate of annual fluxes from 1850 to 2015, updating earlier analyses with new estimates of both historical and current rates of LULCC and including emissions from draining and burning of peatlands in Southeast Asia. For most of the 186 countries included we relied on data from Food and Agriculture Organization to document changes in the areas of croplands and pastures since 1960 and changes in the areas of forests and "other land" since 1990. For earlier years we used other sources of information. We used a bookkeeping model that prescribed changes in carbon density of vegetation and soils for 20 types of ecosystems and five land uses. The total net flux attributable to LULCC over the period 1850-2015 is calculated to have been 145 ± 16 Pg C (1 standard deviation). Most of the emissions were from the tropics (102 ± 5.8 Pg C), generally increasing over time to a maximum of 2.10 Pg C yr-1 in 1997. Outside the tropics emissions were roughly constant at 0.5 Pg C yr-1 until 1940, declined to zero around 1970, and then became negative. For the most recent decade (2006-2015) global net emissions from LULCC averaged 1.11 (±0.35) Pg C yr-1, consisting of a net source from the tropics (1.41 ± 0.17 Pg C yr-1), a net sink in northern midlatitudes (-0.28 ± 0.21 Pg C yr-1), and carbon neutrality in southern midlatitudes.

  6. Historic simulation of net ecosystem carbon balance for the Great Dismal Swamp

    Science.gov (United States)

    Sleeter, Rachel

    2017-01-01

    Estimating ecosystem carbon (C) balance relative to natural disturbances and land management strengthens our understanding of the benefits and tradeoffs of carbon sequestration. We conducted a historic model simulation of net ecosystem C balance in the Great Dismal Swamp, VA. for the 30-year time period of 1985-2015. The historic simulation of annual carbon flux was calculated with the Land Use and Carbon Scenario Simulator (LUCAS) model. The LUCAS model utilizes a state-and-transition simulation model coupled with a carbon stock-flow accounting model to estimate net ecosystem C balance, and long term sequestration rates under various ecological conditions and management strategies. The historic model simulation uses age-structured forest growth curves for four forest species, C stock and flow rates for 8 pools and 14 fluxes, and known data for disturbance and management. The annualized results of C biomass are provided in this data release in the following categories: Growth, Heterotrophic Respiration (Rh), Net Ecosystem Production (NEP), Net Biome Production (NBP), Below-ground Biomass (BGB) Stock, Above-ground Biomass (AGB) Stock, AGB Carbon Loss from Fire, BGB Carbon Loss from Fire, Deadwood Carbon Loss from Management, and Total Carbon Loss. The table also includes the area (annually) of each forest type in hectares: Atlantic white cedar Area (hectares); Cypress-gum Area (hectares); Maple-gum Area (hectares); Pond pine Area (hectares). Net ecosystem production for the Great Dismal Swamp (~ 54,000 ha), from 1985 to 2015 was estimated to be a net sink of 0.97 Tg C. When the hurricane and six historic fire events were modeled, the Great Dismal Swamp became a net source of 0.89 Tg C. The cumulative above and belowground C loss estimated from the South One in 2008 and Lateral West fire in 2011 totaled 1.70 Tg C, while management activities removed an additional 0.01 Tg C. The C loss in below-ground biomass alone totaled 1.38 Tg C, with the balance (0.31 Tg C

  7. Regional carbon fluxes from land use and land cover change in Asia, 1980-2009

    Science.gov (United States)

    Calle, Leonardo; Canadell, Josep G.; Patra, Prabir; Ciais, Philippe; Ichii, Kazuhito; Tian, Hanqin; Kondo, Masayuki; Piao, Shilong; Arneth, Almut; Harper, Anna B.; Ito, Akihiko; Kato, Etsushi; Koven, Charlie; Sitch, Stephen; Stocker, Benjamin D.; Vivoy, Nicolas; Wiltshire, Andy; Zaehle, Sönke; Poulter, Benjamin

    2016-07-01

    We present a synthesis of the land-atmosphere carbon flux from land use and land cover change (LULCC) in Asia using multiple data sources and paying particular attention to deforestation and forest regrowth fluxes. The data sources are quasi-independent and include the U.N. Food and Agriculture Organization-Forest Resource Assessment (FAO-FRA 2015; country-level inventory estimates), the Emission Database for Global Atmospheric Research (EDGARv4.3), the ‘Houghton’ bookkeeping model that incorporates FAO-FRA data, an ensemble of 8 state-of-the-art Dynamic Global Vegetation Models (DGVM), and 2 recently published independent studies using primarily remote sensing techniques. The estimates are aggregated spatially to Southeast, East, and South Asia and temporally for three decades, 1980-1989, 1990-1999 and 2000-2009. Since 1980, net carbon emissions from LULCC in Asia were responsible for 20%-40% of global LULCC emissions, with emissions from Southeast Asia alone accounting for 15%-25% of global LULCC emissions during the same period. In the 2000s and for all Asia, three estimates (FAO-FRA, DGVM, Houghton) were in agreement of a net source of carbon to the atmosphere, with mean estimates ranging between 0.24 to 0.41 Pg C yr-1, whereas EDGARv4.3 suggested a net carbon sink of -0.17 Pg C yr-1. Three of 4 estimates suggest that LULCC carbon emissions declined by at least 34% in the preceding decade (1990-2000). Spread in the estimates is due to the inclusion of different flux components and their treatments, showing the importance to include emissions from carbon rich peatlands and land management, such as shifting cultivation and wood harvesting, which appear to be consistently underreported.

  8. Squaroglitter: A 3,4-Connected Carbon Net

    KAUST Repository

    Prasad, Dasari L. V. K.

    2013-08-13

    Theoretical calculations are presented on a new hypothetical 3,4-connected carbon net (called squaroglitter) incorporating 1,4 cyclohexadiene units. The structure has tetragonal space group P4/mmm (No. 123) symmetry. The optimized geometry shows normal distances, except for some elongated bonds in the cyclobutane ring substructures in the network. Squaroglitter has an indirect bandgap of about 1.0 eV. The hypothetical lattice, whose density is close to graphite, is more stable than other 3,4-connected carbon nets. A relationship to a (4,4)nanotube is explored, as is a potential threading of the lattice with metal needles. © 2013 American Chemical Society.

  9. Net Biome Productivity of different land use at the sites of the Tharandt cluster

    Science.gov (United States)

    Grünwald, T.; Prescher, A.-K.; Bernhofer, Ch.

    2009-04-01

    Within the Tharandt cluster there are 5 flux monitoring sites including 3 CARBOEUROPE main sites. The CARBOEUROPE sites cover typical land use of the region (spruce [monitored since 1996], grassland [since 2003], cropland [since 2004]). For all sites estimates of the Net Biome Productivity (NBP) and its uncertainty have been derived using Net Ecosystem Productivity (NEP) based on the EC measurements and C exports and imports on an annual basis. The crop site is a small C sink (NEP of 30-110gCm-2a-1) only. The annual NEP values are dependent on the cultivated crop species (winter or summer crop). Including C export (harvest) and C import (manure spreading) lead to a considerable C source of 270-540gCm-2a-1. Organic fertilisation (C import) has a strong impact on NBP values expressed in a reduced annual net carbon source. Also, the largest interannual differences of NBP values are found at this site - mainly induced by the existence and the amount of a carbon import due to organic fertilisation. Management practices affect the NBP in a sensitive way at this crop site. Each crop shows a higher C export due to harvest than the annual NEP. To validate the calculated C equivalent using harvested grain biomass modelled NPP values are available. Uncertainty ranges of C export, C import and NBP as well as the grassland and spruce NBP (for comparison) are also stated. In general, land use and management strongly affect the annual NBP of non-forested ecosystems especially. So, this is the second main driver of the C budget besides the interannual variability in meteorological conditions and water availability with its influence on NEP, GPP and TER.

  10. Nitrogen Dynamics are a Key Factor in Explaining Global Land Carbon Sink

    Science.gov (United States)

    Huntzinger, D. N.; Michalak, A. M.; Schwalm, C.; Ciais, P.; Schaefer, K. M.; King, A. W.; Wei, Y.; Cook, R. B.; Fisher, J. B.; Hayes, D. J.; Huang, M.; Ito, A.; Jain, A. K.; Lei, H.; Lu, C.; Maignan, F.; Mao, J.; Parazoo, N.; Peng, S.; Poulter, B.; Ricciuto, D. M.; Shi, X.; Tian, H.; Wang, W.; Zeng, N.; Zhao, F.

    2015-12-01

    The terrestrial carbon cycle plays a critical role in regulating the amount of anthropogenic emissions that remain in the atmosphere. Yet, land-atmosphere carbon dynamics are one of the largest sources of uncertainty in projections of future climate. Reducing this uncertainty requires understanding the relative role of various drivers to land carbon uptake. We use an ensemble of land surface models to quantify the influence of climate, land use history, atmospheric CO2, and nitrogen deposition on the strength of the net land sink over the past 110 years. Each model can be thought of as one realization of terrestrial carbon cycling and the factors most important in controlling land sink strength. Using a series of sensitivity simulations, we identify the dominant drivers to the net land sink that emerge consistently across models, both globally and regionally. We find that the relative importance of external forcing factors on the strength of net land carbon uptake varies considerably across models and depends strongly on whether nitrogen cycling is explicitly simulated. Models without a nitrogen cycle estimate cumulative land carbon uptake (since 1959) that is 3 times greater (93.3 ± 84.1 PgC) than global mass balance constraints (34.6 ± 41.6 PgC). Surprisingly, the greatest impacts are seen in the tropics, where coupled carbon-nitrogen cycle models estimate CO2 fertilization and climate affects that are ~60% weaker than models without a nitrogen cycle. The results highlight the importance of model structure on the inferred sensitivity of land carbon uptake to external forcing factors. The range in sensitivity across models is important for future climate projections since the differences in the processes that explain trends in net land sink strength between models with and without nitrogen dynamics can lead to very different future trajectories of atmospheric CO2 and thus climate.

  11. Spring Hydrology Determines Summer Net Carbon Uptake in Northern Ecosystems

    Science.gov (United States)

    Yi, Yonghong; Kimball, John; Reichle, Rolf H.

    2014-01-01

    Increased photosynthetic activity and enhanced seasonal CO2 exchange of northern ecosystems have been observed from a variety of sources including satellite vegetation indices (such as the Normalized Difference Vegetation Index; NDVI) and atmospheric CO2 measurements. Most of these changes have been attributed to strong warming trends in the northern high latitudes (greater than or equal to 50N). Here we analyze the interannual variation of summer net carbon uptake derived from atmospheric CO2 measurements and satellite NDVI in relation to surface meteorology from regional observational records. We find that increases in spring precipitation and snow pack promote summer net carbon uptake of northern ecosystems independent of air temperature effects. However, satellite NDVI measurements still show an overall benefit of summer photosynthetic activity from regional warming and limited impact of spring precipitation. This discrepancy is attributed to a similar response of photosynthesis and respiration to warming and thus reduced sensitivity of net ecosystem carbon uptake to temperature. Further analysis of boreal tower eddy covariance CO2 flux measurements indicates that summer net carbon uptake is positively correlated with early growing-season surface soil moisture, which is also strongly affected by spring precipitation and snow pack based on analysis of satellite soil moisture retrievals. This is attributed to strong regulation of spring hydrology on soil respiration in relatively wet boreal and arctic ecosystems. These results document the important role of spring hydrology in determining summer net carbon uptake and contrast with prevailing assumptions of dominant cold temperature limitations to high-latitude ecosystems. Our results indicate potentially stronger coupling of boreal/arctic water and carbon cycles with continued regional warming trends.

  12. Spring hydrology determines summer net carbon uptake in northern ecosystems

    Science.gov (United States)

    Yi, Yonghong; Kimball, John S.; Reichle, Rolf H.

    2014-05-01

    Increased photosynthetic activity and enhanced seasonal CO2 exchange of northern ecosystems have been observed from a variety of sources including satellite vegetation indices (such as the normalized difference vegetation index; NDVI) and atmospheric CO2 measurements. Most of these changes have been attributed to strong warming trends in the northern high latitudes (⩾50° N). Here we analyze the interannual variation of summer net carbon uptake derived from atmospheric CO2 measurements and satellite NDVI in relation to surface meteorology from regional observational records. We find that increases in spring precipitation and snow pack promote summer net carbon uptake of northern ecosystems independent of air temperature effects. However, satellite NDVI measurements still show an overall benefit of summer photosynthetic activity from regional warming and limited impact of spring precipitation. This discrepancy is attributed to a similar response of photosynthesis and respiration to warming and thus reduced sensitivity of net ecosystem carbon uptake to temperature. Further analysis of boreal tower eddy covariance CO2 flux measurements indicates that summer net carbon uptake is positively correlated with early growing-season surface soil moisture, which is also strongly affected by spring precipitation and snow pack based on analysis of satellite soil moisture retrievals. This is attributed to strong regulation of spring hydrology on soil respiration in relatively wet boreal and arctic ecosystems. These results document the important role of spring hydrology in determining summer net carbon uptake and contrast with prevailing assumptions of dominant cold temperature limitations to high-latitude ecosystems. Our results indicate potentially stronger coupling of boreal/arctic water and carbon cycles with continued regional warming trends.

  13. Land-use change and carbon sinks: Econometric estimation of the carbon sequestration supply function

    Energy Technology Data Exchange (ETDEWEB)

    Lubowski, Ruben N.; Plantinga, Andrew J.; Stavins, Robert N.

    2001-01-01

    Increased attention by policy makers to the threat of global climate change has brought with it considerable interest in the possibility of encouraging the expansion of forest area as a means of sequestering carbon dioxide. The marginal costs of carbon sequestration or, equivalently, the carbon sequestration supply function will determine the ultimate effects and desirability of policies aimed at enhancing carbon uptake. In particular, marginal sequestration costs are the critical statistic for identifying a cost-effective policy mix to mitigate net carbon dioxide emissions. We develop a framework for conducting an econometric analysis of land use for the forty-eight contiguous United States and employing it to estimate the carbon sequestration supply function. By estimating the opportunity costs of land on the basis of econometric evidence of landowners' actual behavior, we aim to circumvent many of the shortcomings of previous sequestration cost assessments. By conducting the first nationwide econometric estimation of sequestration costs, endogenizing prices for land-based commodities, and estimating land-use transition probabilities in a framework that explicitly considers the range of land-use alternatives, we hope to provide better estimates eventually of the true costs of large-scale carbon sequestration efforts. In this way, we seek to add to understanding of the costs and potential of this strategy for addressing the threat of global climate change.

  14. [Carbon emissions and low-carbon regulation countermeasures of land use change in the city and town concentrated area of central Liaoning Province, China].

    Science.gov (United States)

    Xi, Feng-ming; Liang, Wen-juan; Niu, Ming-fen; Wang, Jiao-yue

    2016-02-01

    Carbon emissions due to land use change have an important impact on global climate change. Adjustment of regional land use patterns has a great scientific significance to adaptation to a changing climate. Based on carbon emission/absorption parameters suitable for Liaoning Province, this paper estimated the carbon emission of land use change in the city and town concentrated area of central Liaoning Province. The results showed that the carbon emission and absorption were separately 308.51 Tg C and 11.64 Tg C from 1997 to 2010. It meant 3.8% of carbon emission. was offset by carbon absorption. Among the 296.87 Tg C net carbon emission of land use change, carbon emission of remaining land use type was 182.24 Tg C, accounting for 61.4% of the net carbon emission, while the carbon emission of land use transformation was 114.63 Tg C, occupying the rest 38.6% of net carbon emission. Through quantifying the mapping relationship between land use change and carbon emission, it was shown that during 1997-2004 the contributions of remaining construction land (40.9%) and cropland transform ation to construction land (40.6%) to carbon emission were larger, but the greater contributions to carbon absorption came from cropland transformation to forest land (38.6%) and remaining forest land (37.5%). During 2004-2010, the land use types for carbon emission and absorption were the same to the period of 1997-2004, but the contribution of remaining construction land to carbon emission increased to 80.6%, and the contribution of remaining forest land to carbon absorption increased to 71.7%. Based on the carbon emission intensity in different land use types, we put forward the low-carbon regulation countermeasures of land use in two aspects. In carbon emission reduction, we should strict control land transformation to construction land, increase the energy efficiency of construction land, and avoid excessive development of forest land and water. In carbon sink increase, we should

  15. A theoretical framework for the net land-to-atmosphere CO2 flux and its implications in the definition of "emissions from land-use change"

    Directory of Open Access Journals (Sweden)

    T. Gasser

    2013-06-01

    Full Text Available We develop a theoretical framework and analysis of the net land-to-atmosphere CO2 flux in order to discuss possible definitions of "emissions from land-use change". The terrestrial biosphere is affected by two perturbations: the perturbation of the global carbon-climate-nitrogen system (CCN with elevated atmospheric CO2, climate change and nitrogen deposition; and the land-use change perturbation (LUC. Here, we progressively establish mathematical definitions of four generic components of the net land-to-atmosphere CO2 flux. The two first components are the fluxes that would be observed if only one perturbation occurred. The two other components are due to the coupling of the CCN and LUC perturbations, which shows the non-linear response of the terrestrial carbon cycle. Thanks to these four components, we introduce three possible definitions of "emissions from land-use change" that are indeed used in the scientific literature, often without clear distinctions, and we draw conclusions as for their absolute and relative behaviors. Thanks to the OSCAR v2 model, we provide quantitative estimates of the differences between the three definitions, and we find that comparing results from studies that do not use the same definition can lead to a bias of up to 20% between estimates of those emissions. After discussion of the limitations of the framework, we conclude on the three major points of this study that should help the community to reconcile modeling and observation of emissions from land-use change. The appendix mainly provides more detailed mathematical expressions of the four components of the net land-to-atmosphere CO2 flux.

  16. North America's net terrestrial carbon exchange with the atmosphere 1990–2009

    Directory of Open Access Journals (Sweden)

    A. W. King

    2014-07-01

    Full Text Available Scientific understanding of the global carbon cycle is required for developing national and international policy to mitigate fossil-fuel CO2 emissions by managing terrestrial carbon uptake. Toward that understanding and as a contribution to the REgional Carbon Cycle Assessment and Processes (RECCAP project, this paper provides a synthesis of net land–atmosphere CO2 exchange for North America over the period (1990–2009. This synthesis is based on results from three different methods: atmospheric inversion, inventory-based methods and terrestrial biosphere modeling. All methods indicate that the North America land surface was a sink for atmospheric CO2, with a net transfer from atmosphere to land. Estimates ranged from −890 to −280 Tg C yr−1, where the atmospheric inversion estimate forms the lower bound of that range (a larger land-sink and the inventory-based estimate the upper (a smaller land sink. Integrating across estimates, "best" estimates (i.e., measures of central tendency are −472 ± 281 Tg C yr−1 based on the mean and standard deviation of the distribution and −360 Tg C yr−1 (with an interquartile range of −496 to −337 based on the median. Considering both the fossil-fuel emissions source and the land sink, our analysis shows that North America was, however, a net contributor to the growth of CO2 in the atmosphere in the late 20th and early 21st century. The continent's CO2 source to sink ratio for this time period was likely in the range of 4 : 1 to 3 : 1.

  17. Country-level net primary production distribution and response to drought and land cover change.

    Science.gov (United States)

    Peng, Dailiang; Zhang, Bing; Wu, Chaoyang; Huete, Alfredo R; Gonsamo, Alemu; Lei, Liping; Ponce-Campos, Guillermo E; Liu, Xinjie; Wu, Yanhong

    2017-01-01

    Carbon sequestration by terrestrial ecosystems can offset emissions and thereby offers an alternative way of achieving the target of reducing the concentration of CO2 in the atmosphere. Net primary production (NPP) is the first step in the sequestration of carbon by terrestrial ecosystems. This study quantifies moderate-resolution imaging spectroradiometer (MODIS) NPP from 2000 to 2014 at the country level along with its response to drought and land cover change. Our results indicate that the combined NPP for 53 countries represents >90% of global NPP. From 2000 to 2014, 29 of these 53 countries had increasing NPP trends, most notably the Central African Republic (23gC/m(2)/y). The top three and top 12 countries accounted for 30% and 60% of total global NPP, respectively, whereas the mean national NPP per unit area in the countries with the 12 lowest values was only around ~300gC/m(2)/y - the exception to this was Brazil, which had an NPP of 850gC/m(2)/y. Large areas of Russia, Argentina, Peru and several countries in southeast Asia showed a marked decrease in NPP (~15gC/m(2)/y). About 37% of the NPP decrease was caused by drought while ~55% of NPP variability was attributed to changes in water availability. Land cover change explained about 20% of the NPP variability. Our findings support the idea that government policies should aim primarily to improve water management in drought-afflicted countries; land use/land cover change policy could also be used as an alternative method of increasing NPP.

  18. Proposal methodology for Land Carbon Accounting across Europe

    Science.gov (United States)

    Simon, A.; Ivanov, E.; Anaya-Romero, M.; Weber, J.-L.

    2012-04-01

    The need to account natural resources as capital, in the same way as we account economic and financial resources, is getting an important awareness-raising channel for governments, producers, and consumers in order to manage the environment capital. Besides that, the forthcoming Part II of the revised System of Integrated Environmental and Economic Accounting will enclose a framework for experimental ecosystem accounts. This conceptual framework is an initiative led by the European Environment Agency and the World Bank WAVES global partnership for which robust data and indicators are needed. In this context, the aim of this work is to demonstrate a preliminary methodology for land carbon account across Europe. The study area covers EU+38. The territorial unit used was the Socio-Ecological Landscape Units based on the Land Cover Functional Units and other geographical dimensions such as relief, belonging to a river basin, or proximity to the sea. Finally, the grid size used for accounting was 1km x 1km. The characteristic indicator considered for ecosystem capital carbon accounts is the carbon content which is derived from the Net Primary Production (NPP) and its removal by agriculture, forestry. Accordingly, the output data obtained were the stocks of carbon recorded in tons of carbon. The current approach is based on the combination of CORINE Land cover, traditional remote sensing (RS) indicators like NDVI - Normalised Difference Vegetation Index and the modern advances on RS techniques where new indicators like GPP (Gross Primary Productivity) and NPP. Other additional attributes were temperature, precipitation and vegetation type or Land cover. Different national and European data sources were used for the analysis as well as downscales procedures. In the present work soil carbon content were assumed to be a fixed fraction. Nevertheless further research will also take into account soil carbon data considering scenarios of land use change.

  19. MISR Level 3 Component Global Land seasonal product in netCDF format V004

    Data.gov (United States)

    National Aeronautics and Space Administration — This file contains the MISR Level 3 Component Global Land product in netCDF format covering a quarter (seasonal) (Suggested Usage: This file contains the global...

  20. Australian net (1950s–1990 soil organic carbon erosion: implications for CO2 emission and land–atmosphere modelling

    Directory of Open Access Journals (Sweden)

    A. Chappell

    2014-05-01

    Full Text Available The debate about soil erosion substantially offsetting fossil fuel emissions and acting as an important source or sink of CO2 remains unresolved. There is little historical land use and management context to this debate which is central to Australia's recent past of European settlement, agricultural expansion and agriculturally-induced soil erosion. We use "catchment" scale (∼25 km2 estimates of 137Cs-derived net (1950s–1990 soil redistribution of all processes (wind, water and tillage to calculate the net soil organic carbon (SOC redistribution across Australia. We approximate the selective removal of SOC at net eroding locations and SOC enrichment of transported sediment and net depositional locations. We map net (1950s–1990 SOC redistribtion across Australia and estimate erosion by all processes ∼4 Tg SOC yr−1 which represents a~loss of ∼2% of the total carbon stock (0–10 cm of Australia. Assuming this net SOC loss is mineralised, the flux (∼15 Tg CO2-e yr−1 represents an omitted 12% of CO2-e emissions from all carbon pools in Australia. Although a small source of uncertainty in the Australian carbon budget, the mass flux interacts with energy and water fluxes and its omission from land surface models likely creates more uncertainty than has been previously recognised.

  1. Interactions between land use change and carbon cycle feedbacks: Land Use and Carbon Cycle Feedbacks

    Energy Technology Data Exchange (ETDEWEB)

    Mahowald, Natalie M. [Cornell Univ., Ithaca, NY (United States); Randerson, James T. [Univ. of California, Irvine, CA (United States); Lindsay, Keith [National Center for Atmospheric Research, Boulder, CO (United States); Munoz, Ernesto [National Center for Atmospheric Research, Boulder, CO (United States); Doney, Scott C. [Woods Hole Oceanographic Inst., Woods Hole, MA (United States); Lawrence, Peter [National Center for Atmospheric Research, Boulder, CO (United States); Schlunegger, Sarah [Cornell Univ., Ithaca, NY (United States); Princeton Univ., NJ (United States); Ward, Daniel S. [Cornell Univ., Ithaca, NY (United States); Princeton Univ., NJ (United States); Lawrence, David [National Center for Atmospheric Research, Boulder, CO (United States); Hoffman, Forrest M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-01-23

    We explore the role of human land use and land cover change (LULCC) in modifying the terrestrial carbon budget in simulations forced by Representative Concentration Pathway 8.5, extended to year 2300 by using the Community Earth System Model, . Overall, conversion of land (e.g., from forest to croplands via deforestation) results in a model-estimated, cumulative carbon loss of 490 Pg C between 1850 and 2300, larger than the 230 Pg C loss of carbon caused by climate change over this same interval. The LULCC carbon loss is a combination of a direct loss at the time of conversion and an indirect loss from the reduction of potential terrestrial carbon sinks. Approximately 40% of the carbon loss associated with LULCC in the simulations arises from direct human modification of the land surface; the remaining 60% is an indirect consequence of the loss of potential natural carbon sinks. Because of the multicentury carbon cycle legacy of current land use decisions, a globally averaged amplification factor of 2.6 must be applied to 2015 land use carbon losses to adjust for indirect effects. This estimate is 30% higher when considering the carbon cycle evolution after 2100. Most of the terrestrial uptake of anthropogenic carbon in the model occurs from the influence of rising atmospheric CO2 on photosynthesis in trees, and thus, model-projected carbon feedbacks are especially sensitive to deforestation.

  2. Interaction effects of climate and land use/land cover change on soil organic carbon sequestration.

    Science.gov (United States)

    Xiong, Xiong; Grunwald, Sabine; Myers, D Brenton; Ross, C Wade; Harris, Willie G; Comerford, Nicolas B

    2014-09-15

    Historically, Florida soils stored the largest amount of soil organic carbon (SOC) among the conterminous U.S. states (2.26 Pg). This region experienced rapid land use/land cover (LULC) shifts and climate change in the past decades. The effects of these changes on SOC sequestration are unknown. The objectives of this study were to 1) investigate the change in SOC stocks in Florida to determine if soils have acted as a net sink or net source for carbon (C) over the past four decades and 2) identify the concomitant effects of LULC, LULC change, and climate on the SOC change. A total of 1080 sites were sampled in the topsoil (0-20 cm) between 2008 and 2009 representing the current SOC stocks, 194 of which were selected to collocate with historical sites (n = 1251) from the Florida Soil Characterization Database (1965-1996) for direct comparison. Results show that SOC stocks significantly differed among LULC classes--sugarcane and wetland contained the highest SOC, followed by improved pasture, urban, mesic upland forest, rangeland, and pineland while crop, citrus and xeric upland forest remained the lowest. The surface 20 cm soils acted as a net sink for C with the median SOC significantly increasing from 2.69 to 3.40 kg m(-2) over the past decades. The SOC sequestration rate was LULC dependent and controlled by climate factors interacting with LULC. Higher temperature tended to accelerate SOC accumulation, while higher precipitation reduced the SOC sequestration rate. Land use/land cover change observed over the past four decades also favored the C sequestration in soils due to the increase in the C-rich wetland area by ~140% and decrease in the C-poor agricultural area by ~20%. Soils are likely to provide a substantial soil C sink considering the climate and LULC projections for this region.

  3. Temporal Land Cover Analysis for Net Ecosystem Improvement

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Yinghai; Coleman, Andre M.; Diefenderfer, Heida L.

    2013-04-09

    We delineated 8 watersheds contributing to previously defined river reaches within the 1,468-km2 historical floodplain of the tidally influenced lower Columbia River and estuary. We assessed land-cover change at the watershed, reach, and restoration site scales by reclassifying remote-sensing data from the National Oceanic and Atmospheric Administration Coastal Change Analysis Program’s land cover/land change product into forest, wetland, and urban categories. The analysis showed a 198.3 km2 loss of forest cover during the first 6 years of the Columbia Estuary Ecosystem Restoration Program, 2001–2006. Total measured urbanization in the contributing watersheds of the estuary during the full 1996-2006 change analysis period was 48.4 km2. Trends in forest gain/loss and urbanization differed between watersheds. Wetland gains and losses were within the margin of error of the satellite imagery analysis. No significant land cover change was measured at restoration sites, although it was visible in aerial imagery, therefore, the 30-m land-cover product may not be appropriate for assessment of early-stage wetland restoration. These findings suggest that floodplain restoration sites in reaches downstream of watersheds with decreasing forest cover will be subject to increased sediment loads, and those downstream of urbanization will experience effects of increased impervious surfaces on hydrologic processes.

  4. NetLand: quantitative modeling and visualization of Waddington's epigenetic landscape using probabilistic potential.

    Science.gov (United States)

    Guo, Jing; Lin, Feng; Zhang, Xiaomeng; Tanavde, Vivek; Zheng, Jie

    2017-05-15

    Waddington's epigenetic landscape is a powerful metaphor for cellular dynamics driven by gene regulatory networks (GRNs). Its quantitative modeling and visualization, however, remains a challenge, especially when there are more than two genes in the network. A software tool for Waddington's landscape has not been available in the literature. We present NetLand, an open-source software tool for modeling and simulating the kinetic dynamics of GRNs, and visualizing the corresponding Waddington's epigenetic landscape in three dimensions without restriction on the number of genes in a GRN. With an interactive and graphical user interface, NetLand can facilitate the knowledge discovery and experimental design in the study of cell fate regulation (e.g. stem cell differentiation and reprogramming). NetLand can run under operating systems including Windows, Linux and OS X. The executive files and source code of NetLand as well as a user manual, example models etc. can be downloaded from http://netland-ntu.github.io/NetLand/ . zhengjie@ntu.edu.sg. Supplementary data are available at Bioinformatics online.

  5. Net Carbon Emissions from Deforestation in Bolivia during 1990-2000 and 2000-2010: Results from a Carbon Bookkeeping Model.

    Science.gov (United States)

    Andersen, Lykke E; Doyle, Anna Sophia; del Granado, Susana; Ledezma, Juan Carlos; Medinaceli, Agnes; Valdivia, Montserrat; Weinhold, Diana

    2016-01-01

    Accurate estimates of global carbon emissions are critical for understanding global warming. This paper estimates net carbon emissions from land use change in Bolivia during the periods 1990-2000 and 2000-2010 using a model that takes into account deforestation, forest degradation, forest regrowth, gradual carbon decomposition and accumulation, as well as heterogeneity in both above ground and below ground carbon contents at the 10 by 10 km grid level. The approach permits detailed maps of net emissions by region and type of land cover. We estimate that net CO2 emissions from land use change in Bolivia increased from about 65 million tons per year during 1990-2000 to about 93 million tons per year during 2000-2010, while CO2 emissions per capita and per unit of GDP have remained fairly stable over the sample period. If we allow for estimated biomass increases in mature forests, net CO2 emissions drop to close to zero. Finally, we find these results are robust to alternative methods of calculating emissions.

  6. Net Carbon Emissions from Deforestation in Bolivia during 1990-2000 and 2000-2010: Results from a Carbon Bookkeeping Model.

    Directory of Open Access Journals (Sweden)

    Lykke E Andersen

    Full Text Available Accurate estimates of global carbon emissions are critical for understanding global warming. This paper estimates net carbon emissions from land use change in Bolivia during the periods 1990-2000 and 2000-2010 using a model that takes into account deforestation, forest degradation, forest regrowth, gradual carbon decomposition and accumulation, as well as heterogeneity in both above ground and below ground carbon contents at the 10 by 10 km grid level. The approach permits detailed maps of net emissions by region and type of land cover. We estimate that net CO2 emissions from land use change in Bolivia increased from about 65 million tons per year during 1990-2000 to about 93 million tons per year during 2000-2010, while CO2 emissions per capita and per unit of GDP have remained fairly stable over the sample period. If we allow for estimated biomass increases in mature forests, net CO2 emissions drop to close to zero. Finally, we find these results are robust to alternative methods of calculating emissions.

  7. DNA Nano-netting Intertexture on Carbon Electrodes

    Institute of Scientific and Technical Information of China (English)

    Xiang Qin LIN; Xiao Hua JIANG; Li Ping LU

    2004-01-01

    Native calf thymus double stranded DNA (ct-dsDNA) is successfully immobilized from solution onto carbon substrates by covalent linkages under an optimized deposition potential of 1.8±0.3 V vs.50 mmol/L NaCl-Ag/AgCl.The long chain DNA fabricates a layer of well conductive nano-netting intertexture, which is stable in pH 14 alkaline solution and in boiling water.The ct-dsDNA modified carbon fiber disk electrode shows two to three orders of magnitude enlarged electrode effective surface area and similarly enlarged voltammetric responses to Co(phen)33+ and dopamine.Thermal dissociated single stranded ct-DNA can also lead to similar result.This modified electrode will find wide applications in the fields of DNA-based electrochemical biosensors.

  8. Net ecosystem carbon exchange of a dry temperate eucalypt forest

    Science.gov (United States)

    Hinko-Najera, Nina; Isaac, Peter; Beringer, Jason; van Gorsel, Eva; Ewenz, Cacilia; McHugh, Ian; Exbrayat, Jean-François; Livesley, Stephen J.; Arndt, Stefan K.

    2017-08-01

    Forest ecosystems play a crucial role in the global carbon cycle by sequestering a considerable fraction of anthropogenic CO2, thereby contributing to climate change mitigation. However, there is a gap in our understanding about the carbon dynamics of eucalypt (broadleaf evergreen) forests in temperate climates, which might differ from temperate evergreen coniferous or deciduous broadleaved forests given their fundamental differences in physiology, phenology and growth dynamics. To address this gap we undertook a 3-year study (2010-2012) of eddy covariance measurements in a dry temperate eucalypt forest in southeastern Australia. We determined the annual net carbon balance and investigated the temporal (seasonal and inter-annual) variability in and environmental controls of net ecosystem carbon exchange (NEE), gross primary productivity (GPP) and ecosystem respiration (ER). The forest was a large and constant carbon sink throughout the study period, even in winter, with an overall mean NEE of -1234 ± 109 (SE) g C m-2 yr-1. Estimated annual ER was similar for 2010 and 2011 but decreased in 2012 ranging from 1603 to 1346 g C m-2 yr-1, whereas GPP showed no significant inter-annual variability, with a mean annual estimate of 2728 ± 39 g C m-2 yr-1. All ecosystem carbon fluxes had a pronounced seasonality, with GPP being greatest during spring and summer and ER being highest during summer, whereas peaks in NEE occurred in early spring and again in summer. High NEE in spring was likely caused by a delayed increase in ER due to low temperatures. A strong seasonal pattern in environmental controls of daytime and night-time NEE was revealed. Daytime NEE was equally explained by incoming solar radiation and air temperature, whereas air temperature was the main environmental driver of night-time NEE. The forest experienced unusual above-average annual rainfall during the first 2 years of this 3-year period so that soil water content remained relatively high and the forest

  9. CARBON SEQUESTRATION SURFACE MINE LANDS

    Energy Technology Data Exchange (ETDEWEB)

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2003-07-24

    Over 160 acres of tree seedlings were planted during the last quarter. This quarter marked the beginning of the installation of new instrumentation and the inspection and calibration of previously installed recording devices. Sampling systems were initiated to quantify initial seedling success as well as height measurements. Nursery seedlings have been inoculated to produce mycorrhizal treated stock for 2004 spring plantings to determine the effects on carbon sequestration. All planting areas in western Kentucky have been sampled with the recording cone penetrometer and the nuclear density gauge to measure soil density.

  10. Accelerating net terrestrial carbon uptake during the warming hiatus due to reduced respiration

    Science.gov (United States)

    Ballantyne, Ashley; Smith, William; Anderegg, William; Kauppi, Pekka; Sarmiento, Jorge; Tans, Pieter; Shevliakova, Elena; Pan, Yude; Poulter, Benjamin; Anav, Alessandro; Friedlingstein, Pierre; Houghton, Richard; Running, Steven

    2017-01-01

    The recent `warming hiatus' presents an excellent opportunity to investigate climate sensitivity of carbon cycle processes. Here we combine satellite and atmospheric observations to show that the rate of net biome productivity (NBP) has significantly accelerated from -0.007 +/- 0.065 PgC yr-2 over the warming period (1982 to 1998) to 0.119 +/- 0.071 PgC yr-2 over the warming hiatus (1998-2012). This acceleration in NBP is not due to increased primary productivity, but rather reduced respiration that is correlated (r = 0.58 P = 0.0007) and sensitive (γ = 4.05 to 9.40 PgC yr-1 per °C) to land temperatures. Global land models do not fully capture this apparent reduced respiration over the warming hiatus; however, an empirical model including soil temperature and moisture observations better captures the reduced respiration.

  11. Accelerating Net Terrestrial Carbon Uptake During the Warming Hiatus Due to Reduced Respiration

    Science.gov (United States)

    Ballantyne, Ashley; Smith, William; Anderegg, William; Kauppi, Pekka; Sarmiento, Jorge; Tans, Pieter; Shevliakova, Elena; Pan, Yude; Poulter, Benjamin; Anav, Alessandro; hide

    2017-01-01

    The recent warming hiatus presents an excellent opportunity to investigate climate sensitivity of carbon cycle processes. Here we combine satellite and atmospheric observations to show that the rate of net biome productivity (NBP) has significantly accelerated from - 0.007 +/- 0.065 PgC yr(exp -2) over the warming period (1982 to 1998) to 0.119 +/- 0.071 PgC yr(exp -2) over the warming hiatus (19982012). This acceleration in NBP is not due to increased primary productivity, but rather reduced respiration that is correlated (r = 0.58; P = 0.0007) and sensitive ( y = 4.05 to 9.40 PgC yr(exp -1) per C) to land temperatures. Global land models do not fully capture this apparent reduced respiration over the warming hiatus; however, an empirical model including soil temperature and moisture observations better captures the reduced respiration.

  12. Land, carbon and water footprints in Taiwan

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yung-Jaan, E-mail: yungjaanlee@gmail.com

    2015-09-15

    The consumer responsibility approach uses footprints as indicators of the total direct and indirect effects of a product or consumption activity. This study used a time-series analysis of three environmental pressures to quantify the total environmental pressures caused by consumption in Taiwan: land footprint, carbon footprint, and water footprint. Land footprint is the pressure from appropriation of biologically productive land and water area. Carbon footprint is the pressure from greenhouse gas emissions. Water footprint is the pressure from freshwater consumption. Conventional carbon footprint is the total CO{sub 2} emitted by a certain activity or the CO{sub 2} accumulation during a product life cycle. This definition cannot be used to convert CO{sub 2} emissions into land units. This study responds to the needs of “CO{sub 2} land” in the footprint family by applying the carbon footprint concept used by GFN. The analytical results showed that consumption by the average Taiwan citizen in 2000 required appropriation of 5.39 gha (hectares of land with global-average biological productivity) and 3.63 gha in 2011 in terms of land footprint. The average Taiwan citizen had a carbon footprint of 3.95 gha in 2000 and 5.94 gha in 2011. These results indicate that separately analyzing the land and carbon footprints enables their trends to be compared and appropriate policies and strategies for different sectors to be proposed accordingly. The average Taiwan citizen had a blue water footprint of 801 m{sup 3} in 2000 and 784 m{sup 3} in 2011. By comparison, their respective global averages were 1.23 gha, 2.36 gha and 163 m{sup 3} blue water in 2011, respectively. Overall, Taiwan revealed higher environmental pressures compared to the rest of the world, demonstrating that Taiwan has become a high footprint state and has appropriated environmental resources from other countries. That is, through its imports of products with embodied pressures and its exports, Taiwan has

  13. Net carbon balance of three full crop rotations at an agricultural site near Gebesee, Germany

    Science.gov (United States)

    Hurkuck, M.; Brümmer, C.; Kolle, O.; Kutsch, W. L.; Moffat, A. M.; Mukwashi, K.; Truckenbrodt, S. C.; Herbst, M.

    2015-12-01

    Continuous eddy-covariance (EC) measurements of biosphere-atmosphere CO2 and H2O exchange have been conducted since 2001 at an agricultural site near Gebesee, Germany, thus providing one of the longest EC time series of European croplands. During the experimental period, winter wheat and winter barley were alternately planted with potatoes, sugar beet, rape, and peppermint covering three full crop rotations (2001-2004, 2005-2009, and 2010-2014). In this study, data of 14 years of net ecosystem CO2 exchange (NEE) and evapotranspiration (E) were re-calculated. Based on these data, we present the net carbon (C) balance (net biome production, NBP) accounting for any additional C input by fertilization and C output by harvest. Further emphasis was placed on the sensitivity of water use efficiency (WUE) and E to climate and crop type. The main aim was to investigate the interannual variability in both NBP and WUE, thus disentangling the impacts of climatic conditions and land management on the net C balance as well as on WUE and E.

  14. Changes in Carbon Emissions in Colombian Savannas Derived From Recent Land use and Land Cover Change

    Science.gov (United States)

    Etter, A.; Sarmiento, A.

    2007-12-01

    The global contribution of carbon emissions from land use dynamics and change to the global carbon (C) cycle is still uncertain, a major concern in global change modeling. Carbon emission from fires in the tropics is significant and represents 9% of the net primary production, and 50% of worldwide C emissions from fires are attributable to savanna fires. Such emissions may vary significantly due to differences in ecosystem types. Most savanna areas are devoted to grazing land uses making methane emissions also important in savanna ecosystems. Land use change driven by intensification of grazing and cropping has become a major factor affecting C emission dynamics from savanna regions. Colombia has some 17 MHa of mesic savannas which have been historically burned. Due to changes in market demands and improved accessibility during the last 20 years, important areas of savannas changed land use from predominantly extensive grazing to crops and intensive grazing systems. This research models and evaluates the impacts of such land use changes on the spatial and temporal burning patterns and C emissions in the Orinoco savannas of Colombia. We address the effects of land use change patterns using remote sensing data from MODIS and Landsat, ecosystem mapping products, and spatial GIS analysis. First we map the expansion of the agricultural frontier from the 1980s-2000s. We then model the changes in land use from the 1980s using a statistical modeling approach to analyze and quantify the impact of accessibility, ecosystem type and land tenure. We calculate the effects on C emissions from fire regimes and other sources of C based on patterns and extent of burned areas in the 2000s for different savanna ecosystem types and land uses. In the Llanos the fire regime exhibits a marked seasonal variability with most fire events occurring during the dry season between December-March. Our analysis shows that fire frequencies vary consistently between 0.6 and 2.8 fires.yr-1 per 2

  15. Impact of land use change on the land atmosphere carbon flux of South and South East Asia: A Synthesis of Dynamic Vegetation Model Results

    Science.gov (United States)

    Cervarich, M.; Shu, S.; Jain, A. K.; Poulter, B.; Stocker, B.; Arneth, A.; Viovy, N.; Kato, E.; Wiltshire, A.; Koven, C.; Sitch, S.; Zeng, N.; Friedlingstein, P.

    2015-12-01

    Understanding our present day carbon cycle and possible solutions to recent increases in atmospheric carbon dioxide is dependent upon quantifying the terrestrial carbon budget. Currently, global land cover and land use change is estimated to emit 0.9 PgC yr-1 compared to emissions due to fossil fuel combustion and cement production of 8.4 PgC yr-1. South and Southeast Asia (India, Nepal, Bhutan, Bangladesh, Burma, Thailand, Laos, Vietnam, Cambodia, Malaysia, Philippines, Indonesia, Pakistan, Myanmar, and Singapore) is a region of rapid land cover and land use change due to the continuous development of agriculture, deforestation, reforestation, afforestation, and the increased demand of land for people to live. In this study, we synthesize outputs of nine models participated in Global Carbon Budget Project to identify the carbon budget of South and southeast Asia, diagnose the contribution of land cover and land use change to carbon emissions and assess areas of uncertainty in the suite of models. Uncertainty is determined using the standard deviation and the coefficient of variation of net ecosystem exchange and its component parts. Results show the region's terrestrial biosphere was a source of carbon emissions from the 1980 to the early 1990s. During the same time period, land cover and land use change increasingly contributed to carbon emission. In the most recent two decades, the region became a carbon sink since emission due to land cover land use changes. Spatially, the greatest total emissions occurred in the tropical forest of Southeast Asia. Additionally, this is the subregion with the greatest uncertainty and greatest biomass. Model uncertainty is shown to be proportional to total biomass. The atmospheric impacts of ENSO are shown to suppress the net biosphere productivity in South and Southeast Asia leading to years of increased carbon emissions.

  16. Long term net gains in coastal blue carbon stocks: A search for terrestrial drivers?

    Science.gov (United States)

    Clarke, Jessica; Austin, William; Smeaton, Craig; Winterton, Cathy; Bresnan, Eileen; Davidson, Keith; Lo Giudice Cappelli Lo Giudice Cappelli, Elena; Green, Jade

    2017-04-01

    Peat and Organic soils covers nearly 66% of Scotland, representing over 50% of the UK's soil carbon stocks. Natural processes such as peatland erosion are accelerated by human activities, such as land management and potentially by the impacts of climate change. We present evidence from the isle of Shetland's west coast voes (sea lochs or fjords) to suggest this process may have accelerated since medieval times. This work is supported by the analyses of short sediment Craib cores (triplicate coring) recovered from 17 sites. We present preliminary chronologies supported by radiocarbon dating and sediment characteristics that highlight both changes in the rate of accumulation and source of sedimentary organic carbon to the west coast Shetland voes during the late Holocene. Scottish coastal sediments contain a significant blue carbon stock, a significant proportion of which derives directly from terrestrial sources. The loss of peatland carbon represents a potentially important contribution (i.e. net gain) in refractory carbon within the marine environment and we present preliminary estimates to assess the significance of these large scale transfers and the subsidy of carbon to the coastal ocean.

  17. Black carbon reduction will weaken the aerosol net cooling effect

    Directory of Open Access Journals (Sweden)

    Z. L. Wang

    2014-12-01

    Full Text Available Black carbon (BC, a distinct type of carbonaceous material formed from the incomplete combustion of fossil and biomass based fuels under certain conditions, can interact with solar radiation and clouds through its strong light-absorption ability, thereby warming the Earth's climate system. Some studies have even suggested that global warming could be slowed down in a short term by eliminating BC emission due to its short lifetime. In this study, we estimate the influence of removing some sources of BC and other co-emitted species on the aerosol radiative effect by using an aerosol-climate coupled model BCC_AGCM2.0.1_CUACE/Aero, in combination with the aerosol emissions from the Representative Concentration Pathways (RCPs scenarios. We find that the global annual mean aerosol net cooling effect at the top of the atmosphere (TOA will be enhanced by 0.12 W m−2 compared with present-day conditions if the BC emission is reduced exclusively to the level projected for 2100 based on the RCP2.6 scenario. This will be beneficial for the mitigation of global warming. However, the global annual mean aerosol net cooling effect at the TOA will be weakened by 1.7–2.0 W m−2 relative to present-day conditions if emissions of BC and co-emitted sulfur dioxide and organic carbon are simultaneously reduced as the most close conditions to the actual situation to the level projected for 2100 in different ways based on the RCP2.6, RCP4.5, and RCP8.5 scenarios. Because there are no effective ways to remove the BC exclusively without influencing the other co-emitted components, our results therefore indicate that a reduction in BC emission can lead to an unexpected warming on the Earth's climate system in the future.

  18. Effects of Land Use Change for Crops on Water and Carbon Budgets in the Midwest USA

    Directory of Open Access Journals (Sweden)

    Jian Sun

    2017-02-01

    Full Text Available Increasing demand for food and bioenergy has altered the global landscape dramatically in recent years. Land use and land cover change affects the environmental system in many ways through biophysical and biogeochemical mechanisms. In this study, we evaluate the impacts of land use and land cover change driven by recent crop expansion and conversion on the water budget, carbon exchange, and carbon storage in the Midwest USA. A dynamic global vegetation model was used to simulate and examine the impacts of landscape change in a historical case based on crop distribution data from the United States Department of Agriculture National Agricultural Statistics Services. The simulation results indicate that recent crop expansion not only decreased soil carbon sequestration (60 Tg less of soil organic carbon and net carbon flux into ecosystems (3.7 Tg·year−1 less of net biome productivity, but also lessened water consumption through evapotranspiration (1.04 × 1010 m3·year−1 less over 12 states in the Midwest. More water yield at the land surface does not necessarily make more water available for vegetation. Crop residue removal might also exacerbate the soil carbon loss.

  19. Prediction on Carbon/Carbon Composites Ablative Performance by Artificial Neutral Net

    Institute of Scientific and Technical Information of China (English)

    Guanghui BAI; Songhe MENG; Boming ZHANG; Yang LIU

    2008-01-01

    A preliminary estimation of ablation property for carbon-carbon composites by artificial neutral net (ANN) method was presented.It was found that the carbon-carbon composites' density,degree of graphitization and the sort of matrix are the key controlling factors for its ablative performance.Then,a brief fuzzy mathe-matical relationship was established between these factors and ablative performance.Through experiments,the performance of the ANN was evaluated,which was used in the ablative performance prediction of C/C composites.When the training set,the structure and the training parameter of the net change,the best match ratio of these parameters was achieved.Based on the match ratio,this paper forecasts and evalu-ates the carbon-carbon ablation performance.Through experiences,the ablative performance prediction of carbon-carbon using ANN can achieve the line ablation rate,which satisfies the need of precision of practical engineering fields.

  20. A novel assessment of the role of land-use and land-cover change in the global carbon cycle, using a new Dynamic Global Vegetation Model version of the CABLE land surface model

    Science.gov (United States)

    Haverd, Vanessa; Smith, Benjamin; Nieradzik, Lars; Briggs, Peter; Canadell, Josep

    2017-04-01

    In recent decades, terrestrial ecosystems have sequestered around 1.2 PgC y-1, an amount equivalent to 20% of fossil-fuel emissions. This land carbon flux is the net result of the impact of changing climate and CO2 on ecosystem productivity (CO2-climate driven land sink ) and deforestation, harvest and secondary forest regrowth (the land-use change (LUC) flux). The future trajectory of the land carbon flux is highly dependent upon the contributions of these processes to the net flux. However their contributions are highly uncertain, in part because the CO2-climate driven land sink and LUC components are often estimated independently, when in fact they are coupled. We provide a novel assessment of global land carbon fluxes (1800-2015) that integrates land-use effects with the effects of changing climate and CO2 on ecosystem productivity. For this, we use a new land-use enabled Dynamic Global Vegetation Model (DGVM) version of the CABLE land surface model, suitable for use in attributing changes in terrestrial carbon balance, and in predicting changes in vegetation cover and associated effects on land-atmosphere exchange. In this model, land-use-change is driven by prescribed gross land-use transitions and harvest areas, which are converted to changes in land-use area and transfer of carbon between pools (soil, litter, biomass, harvested wood products and cleared wood pools). A novel aspect is the treatment of secondary woody vegetation via the coupling between the land-use module and the POP (Populations Order Physiology) module for woody demography and disturbance-mediated landscape heterogeneity. Land-use transitions to and from secondary forest tiles modify the patch age distribution within secondary-vegetated tiles, in turn affecting biomass accumulation and turnover rates and hence the magnitude of the secondary forest sink. The resulting secondary forest patch age distribution also influences the magnitude of the secondary forest harvest and clearance fluxes

  1. Simulated Net Ecosystem Carbon Balance of Western US Forests Under Contemporary Climate and Management

    Science.gov (United States)

    Yang, Z.; Law, B. E.; Jones, M. O.

    2015-12-01

    Previous projections of the contemporary forest carbon balance in the western US showed uncertainties associated with impacts of climate extremes and a coarse spatio-temporal resolution implemented over heterogeneous mountain regions. We modified the Community Land Model (CLM) 4.5 to produce 4km resolution forest carbon changes with drought, fire and management in the western US. We parameterized the model with species data using local plant trait observations for 30 species. To quantify uncertainty, we evaluated the model with data from flux sites, inventories and ancillary data in the region. Simulated GPP was lower than the measurements at our AmeriFlux sites by 17-22%. Simulated burned area was generally higher than Landsat observations, suggesting the model overestimates fire emissions with the new fire model. Landsat MTBS data show high severity fire represents only a small portion of the total burnt area (12-14%), and no increasing trend from 1984 to 2011. Moderate severity fire increased ~0.23%/year due to fires in the Sierra Nevada (Law & Waring 2014). Oregon, California, and Washington were a net carbon sink, and net ecosystem carbon balance (NECB) declined in California over the past 15 years, partly due to drought impacts. Fire emissions were a small portion of the regional carbon budget compared with the effect of harvest removals. Fossil fuel emissions in CA are more than 3x that of OR and WA combined, but are lower per capita. We also identified forest regions that are most vulnerable to climate-driven transformations and to evaluate the effects of management strategies on forest NECB. Differences in forest NECB among states are strongly influenced by the extent of drought (drier longer in the SW) and management intensity (higher in the PNW).

  2. A Restricted Boltzman Neural Net to Infer Carbon Uptake from OCO-2 Satellite Data

    Science.gov (United States)

    Halem, M.; Dorband, J. E.; Radov, A.; Barr-Dallas, M.; Gentine, P.

    2015-12-01

    For several decades, scientists have been using satellite observations to infer climate budgets of terrestrial carbon uptake employing inverse methods in conjunction with ecosystem models and coupled global climate models. This is an extremely important Big Data calculation today since the net annual photosynthetic carbon uptake changes annually over land and removes on average ~20% of the emissions from human contributions to atmospheric loading of CO2 from fossil fuels. Unfortunately, such calculations have large uncertainties validated with in-situ networks of measuring stations across the globe. One difficulty in using satellite data for these budget calculations is that the models need to assimilate surface fluxes of CO2 as well as soil moisture, vegatation cover and the eddy covariance of latent and sensible heat to calculate the carbon fixed in the soil while satellite spectral observations only provide near surface concentrations of CO2. In July 2014, NASA successfully launched OCO-2 which provides 3km surface measurements of CO2 over land and oceans. We have collected nearly one year of Level 2 XCO2 data from the OCO-2 satellite for 3 sites of ~200 km2 at equatorial, temperate and high latitudes. Each selected site was part of the Fluxnet or ARM system with tower stations for measuring and collecting CO2 fluxes on an hourly basis, in addition to eddy transports of the other parameters. We are also planning to acquire the 4km NDVI products from MODIS and registering the data to the 3km XCO2 footprints for the three sites. We have implemented a restricted Boltzman machine on the quantum annealing D-Wave computer, a novel deep learning neural net, to be used for training with station data to infer CO2 fluxes from collocated XCO2, MODIS vegetative land cover and MERRA reanalysis surface exchange products. We will present performance assessments of the D-Wave Boltzman machine for generating XCO2 fluxes from the OCO-2 satellite observations for the 3 sites by

  3. CARBON SEQUESTRATION ON SURFACE MINE LANDS

    Energy Technology Data Exchange (ETDEWEB)

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2005-06-22

    An area planted in 2004 on Bent Mountain in Pike County was shifted to the Department of Energy project to centralize an area to become a demonstration site. An additional 98.3 acres were planted on Peabody lands in western Kentucky and Bent Mountain to bring the total area under study by this project to 556.5 acres as indicated in Table 2. Major efforts this quarter include the implementation of new plots that will examine the influence of differing geologic material on tree growth and survival, water quality and quantity and carbon sequestration. Normal monitoring and maintenance was conducted and additional instrumentation was installed to monitor the new areas planted.

  4. Alaska LandCarbon wetland distribution map

    Science.gov (United States)

    Wylie, Bruce K.; Pastick, Neal J.

    2017-01-01

    This product provides regional estimates of specific wetland types (bog and fen) in Alaska. Available wetland types mapped by the National Wetlands Inventory (NWI) program were re-classed into bog, fen, and other. NWI mapping of wetlands was only done for a portion of the area so a decision tree mapping algorithm was then developed to estimate bog, fen, and other across the state of Alaska using remote sensing and GIS spatial data sets as inputs. This data was used and presented in two chapters on the USGS Alaska LandCarbon Report.

  5. Trends in the Global Net Land Sink and Their Sensitivity to Environmental Forcing Factors: Results From the Multi-Scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP)

    Science.gov (United States)

    Huntzinger, D. N.; Schwalm, C. R.; Michalak, A. M.; Wei, Y.; Cook, R. B.; Schaefer, K. M.; Jacobson, A. R.; Arain, M. A.; Ciais, P.; Fisher, J. B.; Hayes, D. J.; Huang, M.; Huang, S.; Ito, A.; Jain, A.; Lei, H.; Lu, C.; Maignan, F.; Mao, J.; Parazoo, N.; Peng, S.; Peng, C.; Poulter, B.; Ricciuto, D. M.; Shi, X.; Tian, H.; Zeng, N.; Zhao, F.; Zhu, Q.; Wang, W.

    2014-12-01

    Predictions of future climate depend strongly on trends in net uptake or release of carbon by the land biosphere. However, model estimates of the strength of the net global land sink during the Industrial Era vary widely. Here we evaluate results from an ensemble of uncoupled models taken from the Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP) and forced by the same input fields. When compared to estimates inferred from atmospheric CO2 observations (i.e., fossil fuel emission + net land use change - atmospheric increase - ocean uptake), MsTMIP models estimate, on average, a stronger global net land uptake of carbon (e.g., -0.3 to 8.7 Pg C/yr from 2000 to 2010, where a negative flux represents a net release to the atmosphere). Some models consistently show the land surface as a net source of carbon to the atmosphere, which is inconsistent with the other terms in the global anthropogenic CO2 budget. In addition, regional differences in land carbon exchange are compared across models and to estimates derived from atmospheric inversions and inventory based approaches. Using the semi-factorial simulations of the MsTMIP activity, we examine how model estimates of the cumulative global net land sink diverge over the period 1900 to 2010, and the degree to which model sensitivity to forcing factors contribute to this divergence. We link differences in estimates of the cumulative land sink back to each model's sensitivity to climate variability, CO2 fertilization, nitrogen limitation, and net land-use change. Throughout the 110-year time period, the strength of carbon uptake in most models appears to be strongly sensitive to atmospheric CO2 concentrations (CO2 fertilization effect). The strength of this relationship, however, varies across models depending on model structure (e.g., stronger CO2 fertilization effect in models without an interactive nitrogen cycle with N limitations) and across decades (e.g., strong sensitivity of net flux to

  6. Carbon Sequestration on Surface Mine Lands

    Energy Technology Data Exchange (ETDEWEB)

    Donald H. Graves; Christopher Barton; Bon Jun Koo; Richard Sweigard; Richard Warner

    2004-11-30

    The first quarter of 2004 was dedicated to tree planting activities in two locations in Kentucky. During the first year of this project there was not available mine land to plant in the Hazard area, so 107 acres were planted in the Martin County mine location. This year 120 acres were planted in the Hazard area to compensate for the prior year and an additional 57 acres were planted on Peabody properties in western Kentucky. Additional sets of special plots were established on each of these areas that contained 4800 seedlings each for carbon sequestration demonstrations. Plantings were also conducted to continue compaction and water quality studies on the newly established areas as well as continual measurements of the first year's plantings. Total plantings on this project now amount to 357 acres containing 245,960 seedlings. During the second quarter of this year monitoring systems were established for all the new research areas. Weather data pertinent to the research as well as hydrology and water quality monitoring continues to be conducted on all areas. Studies established to assess specific questions pertaining to carbon flux and the invasion of the vegetation by small mammals are being quantified. Experimental practices initiated with this research project will eventually allow for the planting on long steep slopes with loose grading systems and allow mountain top removal areas to be constructed with loose spoil with no grading of the final layers of rooting material when establishing trees for the final land use designation. Monitoring systems have been installed to measure treatment effects on both above and below ground carbon and nitrogen pools in the planting areas. Soil and tissue samples were collected from both years planting and analyses were conducted in the laboratory. Examination of decomposition and heterotropic respiration on carbon cycling in the reforestation plots continued during the reporting period. Entire planted trees were

  7. Multiple independent constraints help resolve net ecosystem carbon exchange under nutrient limitation

    Science.gov (United States)

    Thornton, P. E.; Metcalfe, D.; Oren, R.; Ricciuto, D. M.

    2014-12-01

    The magnitude, spatial distribution, and variability of land net ecosystem exchange of carbon (NEE) are important determinants of the trajectory of atmospheric carbon dioxide concentration. Independent observational constraints provide important clues regarding NEE and its component fluxes, with information available at multiple spatial scales: from cells, to leaves, to entire organisms and collections of organisms, to complex landscapes and up to continental and global scales. Experimental manipulations, ecosystem observations, and process modeling all suggest that the components of NEE (photosynthetic gains, and respiration and other losses) are controlled in part by the availability of mineral nutrients, and that nutrient limitation is a common condition in many biomes. Experimental and observational constraints at different spatial scales provide a complex and sometimes puzzling picture of the nature and degree of influence of nutrient availability on carbon cycle processes. Photosynthetic rates assessed at the cellular and leaf scales are often higher than the observed accumulation of carbon in plant and soil pools would suggest. We infer that a down-regulation process intervenes between carbon uptake and plant growth under conditions of nutrient limitation, and several down-regulation mechanisms have been hypothesized and tested. A recent evaluation of two alternative hypotheses for down-regulation in the light of whole-plant level flux estimates indicates that some plants take up and store extra carbon, releasing it to the environment again on short time scales. The mechanism of release, either as additional autotrophic respiration or as exudation belowground is unclear, but has important consequences for long-term ecosystem state and response to climate change signals. Global-scale constraints from atmospheric concentration and isotopic composition data help to resolve this question, ultimately focusing attention on land use fluxes as the most uncertain

  8. Committed carbon emissions, deforestation, and community land conversion from oil palm plantation expansion in West Kalimantan, Indonesia.

    Science.gov (United States)

    Carlson, Kimberly M; Curran, Lisa M; Ratnasari, Dessy; Pittman, Alice M; Soares-Filho, Britaldo S; Asner, Gregory P; Trigg, Simon N; Gaveau, David A; Lawrence, Deborah; Rodrigues, Hermann O

    2012-05-08

    Industrial agricultural plantations are a rapidly increasing yet largely unmeasured source of tropical land cover change. Here, we evaluate impacts of oil palm plantation development on land cover, carbon flux, and agrarian community lands in West Kalimantan, Indonesian Borneo. With a spatially explicit land change/carbon bookkeeping model, parameterized using high-resolution satellite time series and informed by socioeconomic surveys, we assess previous and project future plantation expansion under five scenarios. Although fire was the primary proximate cause of 1989-2008 deforestation (93%) and net carbon emissions (69%), by 2007-2008, oil palm directly caused 27% of total and 40% of peatland deforestation. Plantation land sources exhibited distinctive temporal dynamics, comprising 81% forests on mineral soils (1994-2001), shifting to 69% peatlands (2008-2011). Plantation leases reveal vast development potential. In 2008, leases spanned ∼65% of the region, including 62% on peatlands and 59% of community-managed lands, yet oil palm, generating 26% of net carbon emissions. Intact forest cover declines to 4%, and the proportion of emissions sourced from peatlands increases 38%. Prohibiting intact and logged forest and peatland conversion to oil palm reduces emissions only 4% below BAU, because of continued uncontrolled fire. Protecting logged forests achieves greater carbon emissions reductions (21%) than protecting intact forests alone (9%) and is critical for mitigating carbon emissions. Extensive allocated leases constrain land management options, requiring trade-offs among oil palm production, carbon emissions mitigation, and maintaining community landholdings.

  9. Carbon Flux to the Atmosphere from Land-Use Changes: 1850 to 1990

    Energy Technology Data Exchange (ETDEWEB)

    Houghton, R.A.

    2001-02-22

    The database documented in this numeric data package, a revision to a database originally published by the Carbon Dioxide Information Analysis Center (CDIAC) in 1995, consists of annual estimates, from 1850 through 1990, of the net flux of carbon between terrestrial ecosystems and the atmosphere resulting from deliberate changes in land cover and land use, especially forest clearing for agriculture and the harvest of wood for wood products or energy. The data are provided on a year-by-year basis for nine regions (North America, South and Central America, Europe, North Africa and the Middle East, Tropical Africa, the Former Soviet Union, China, South and Southeast Asia, and the Pacific Developed Region) and the globe. Some data begin earlier than 1850 (e.g., for six regions, areas of different ecosystems are provided for the year 1700) or extend beyond 1990 (e.g., fuelwood harvest in South and Southeast Asia, by forest type, is provided through 1995). The global net flux during the period 1850 to 1990 was 124 Pg of carbon (1 petagram = 10{sup 15} grams). During this period, the greatest regional flux was from South and Southeast Asia (39 Pg of carbon), while the smallest regional flux was from North Africa and the Middle East (3 Pg of carbon). For the year 1990, the global total net flux was estimated to be 2.1 Pg of carbon.

  10. Carbon stocks of different land uses in the Kumrat valley, Hindu Kush Region of Pakistan

    Institute of Scientific and Technical Information of China (English)

    Adnan Ahmad; Syed Moazzam Nizami

    2015-01-01

    Changes in land use cover, particularly from forest to agriculture, is a major contributing factor in increasing carbon dioxide (CO2) level in the atmosphere. Using satellite images of 1999 and 2011, land use and land use changes in the Kumrat valley KPK, Pakistan, were determined:a net decrease of 11.56 and 7.46%occurred in forest and rangeland, while 100% increase occurred in agriculture land (AL). Biomass in different land uses, forest land (FL), AL, and range land (RL) was determined by field inventory. From the biomass data, the amount of carbon was calculated, considering 50%of the biomass as carbon. Soil carbon was also determined to a depth of 0–15 and 16–30 cm. The average carbon stocks (C stocks) in all land uses ranged from 28.62 ± 13.8 t ha-1 in AL to 486.6 ± 32.4 t ha-1 in pure Cedrus deodara forest. The results of the study confirmed that forest soil and vegeta-tion stored the maximum amount of carbon followed by RL. Conversion of FL and RL to AL not only leads to total loss of about 56% (from FL conversion) and 37% (RL conversion) of soil carbon in the last decades but also the loss of a valuable carbon sink. In order to meet the emis-sions reduction obligations of the Kyoto Protocol, Con-servation of forest and RL in the mountainous regions of the Hindu Kush will help Pakistan to meet its emissions reduction goals under the Kyoto Protocol.

  11. The Net Carbon Flux due to Deforestation and Forest Re-Growth in the Brazilian Amazon: Analysis using a Process-Based Model

    Science.gov (United States)

    Hirsch, A. I.; Little, W. S.; Houghton, R. A.; Scott, N. A.; White, J. D.

    2004-01-01

    We developed a process-based model of forest growth, carbon cycling, and land cover dynamics named CARLUC (for CARbon and Land Use Change) to estimate the size of terrestrial carbon pools in terra firme (non-flooded) forests across the Brazilian Legal Amazon and the net flux of carbon resulting from forest disturbance and forest recovery from disturbance. Our goal in building the model was to construct a relatively simple ecosystem model that would respond to soil and climatic heterogeneity that allows us to study of the impact of Amazonian deforestation, selective logging, and accidental fire on the global carbon cycle. This paper focuses on the net flux caused by deforestation and forest re-growth over the period from 1970-1998. We calculate that the net flux to the atmosphere during this period reached a maximum of approx. 0.35 PgC/yr (1PgC = 1 x 10(exp I5) gC) in 1990, with a cumulative release of approx. 7 PgC from 1970- 1998. The net flux is higher than predicted by an earlier study by a total of 1 PgC over the period 1989-1 998 mainly because CARLUC predicts relatively high mature forest carbon storage compared to the datasets used in the earlier study. Incorporating the dynamics of litter and soil carbon pools into the model increases the cumulative net flux by approx. 1 PgC from 1970-1998, while different assumptions about land cover dynamics only caused small changes. The uncertainty of the net flux, calculated with a Monte-Carlo approach, is roughly 35% of the mean value (1 SD).

  12. The Net Carbon Flux due to Deforestation and Forest Re-Growth in the Brazilian Amazon: Analysis using a Process-Based Model

    Science.gov (United States)

    Hirsch, A. I.; Little, W. S.; Houghton, R. A.; Scott, N. A.; White, J. D.

    2004-01-01

    We developed a process-based model of forest growth, carbon cycling, and land cover dynamics named CARLUC (for CARbon and Land Use Change) to estimate the size of terrestrial carbon pools in terra firme (non-flooded) forests across the Brazilian Legal Amazon and the net flux of carbon resulting from forest disturbance and forest recovery from disturbance. Our goal in building the model was to construct a relatively simple ecosystem model that would respond to soil and climatic heterogeneity that allows us to study of the impact of Amazonian deforestation, selective logging, and accidental fire on the global carbon cycle. This paper focuses on the net flux caused by deforestation and forest re-growth over the period from 1970-1998. We calculate that the net flux to the atmosphere during this period reached a maximum of approx. 0.35 PgC/yr (1PgC = 1 x 10(exp I5) gC) in 1990, with a cumulative release of approx. 7 PgC from 1970- 1998. The net flux is higher than predicted by an earlier study by a total of 1 PgC over the period 1989-1 998 mainly because CARLUC predicts relatively high mature forest carbon storage compared to the datasets used in the earlier study. Incorporating the dynamics of litter and soil carbon pools into the model increases the cumulative net flux by approx. 1 PgC from 1970-1998, while different assumptions about land cover dynamics only caused small changes. The uncertainty of the net flux, calculated with a Monte-Carlo approach, is roughly 35% of the mean value (1 SD).

  13. Historical Carbon Dioxide Emissions Caused by Land-Use Changes are Possibly Larger than Assumed

    Science.gov (United States)

    Arneth, A.; Sitch, S.; Pongratz, J.; Stocker, B. D.; Ciais, P.; Poulter, B.; Bayer, A. D.; Bondeau, A.; Calle, L.; Chini, L. P.; hide

    2017-01-01

    The terrestrial biosphere absorbs about 20% of fossil-fuel CO2 emissions. The overall magnitude of this sink is constrained by the difference between emissions, the rate of increase in atmospheric CO2 concentrations, and the ocean sink. However, the land sink is actually composed of two largely counteracting fluxes that are poorly quantified: fluxes from land-use change andCO2 uptake by terrestrial ecosystems. Dynamic global vegetation model simulations suggest that CO2 emissions from land-use change have been substantially underestimated because processes such as tree harvesting and land clearing from shifting cultivation have not been considered. As the overall terrestrial sink is constrained, a larger net flux as a result of land-use change implies that terrestrial uptake of CO2 is also larger, and that terrestrial ecosystems might have greater potential to sequester carbon in the future. Consequently, reforestation projects and efforts to avoid further deforestation could represent important mitigation pathways, with co-benefits for biodiversity. It is unclear whether a larger land carbon sink can be reconciled with our current understanding of terrestrial carbon cycling. Our possible underestimation of the historical residual terrestrial carbon sink adds further uncertainty to our capacity to predict the future of terrestrial carbon uptake and losses.

  14. Historical carbon dioxide emissions caused by land-use changes are possibly larger than assumed

    Science.gov (United States)

    Arneth, A.; Sitch, S.; Pongratz, J.; Stocker, B. D.; Ciais, P.; Poulter, B.; Bayer, A. D.; Bondeau, A.; Calle, L.; Chini, L. P.; Gasser, T.; Fader, M.; Friedlingstein, P.; Kato, E.; Li, W.; Lindeskog, M.; Nabel, J. E. M. S.; Pugh, T. A. M.; Robertson, E.; Viovy, N.; Yue, C.; Zaehle, S.

    2017-01-01

    The terrestrial biosphere absorbs about 20% of fossil-fuel CO2 emissions. The overall magnitude of this sink is constrained by the difference between emissions, the rate of increase in atmospheric CO2 concentrations, and the ocean sink. However, the land sink is actually composed of two largely counteracting fluxes that are poorly quantified: fluxes from land-use change and CO2 uptake by terrestrial ecosystems. Dynamic global vegetation model simulations suggest that CO2 emissions from land-use change have been substantially underestimated because processes such as tree harvesting and land clearing from shifting cultivation have not been considered. As the overall terrestrial sink is constrained, a larger net flux as a result of land-use change implies that terrestrial uptake of CO2 is also larger, and that terrestrial ecosystems might have greater potential to sequester carbon in the future. Consequently, reforestation projects and efforts to avoid further deforestation could represent important mitigation pathways, with co-benefits for biodiversity. It is unclear whether a larger land carbon sink can be reconciled with our current understanding of terrestrial carbon cycling. Our possible underestimation of the historical residual terrestrial carbon sink adds further uncertainty to our capacity to predict the future of terrestrial carbon uptake and losses.

  15. Carbon Storage in Mountain Land Use Systems in Northern Thailand

    OpenAIRE

    Narit Yimyam; Sithichai Lordkaew; Benjavan Rerkasem

    2016-01-01

    Conversion of forested land for agriculture has obvious detrimental effects on its ecological functions, but these effects are not uniform. Mountain land use systems are diverse, encompassing managed forests and cultivated land. This study examined land use systems in 3 mountain villages in northern Thailand with different patterns of cultivation and evaluated the amount of carbon they have accumulated. Land use and management by individual farmers and communities were determined by interview...

  16. Carbon cycling under 300 years of land use change: importance of the secondary vegetation sink

    Science.gov (United States)

    Shevliakova, Elena; Pacala, Stephen W.; Malyshev, Sergey; Hurtt, George C.; Milly, P.C.D.; Caspersen, John P.; Sentman, Lori T.; Fisk, Justin P.; Wirth, Christian; Crevoisier, Cyril

    2009-01-01

    We have developed a dynamic land model (LM3V) able to simulate ecosystem dynamics and exchanges of water, energy, and CO2 between land and atmosphere. LM3V is specifically designed to address the consequences of land use and land management changes including cropland and pasture dynamics, shifting cultivation, logging, fire, and resulting patterns of secondary regrowth. Here we analyze the behavior of LM3V, forced with the output from the Geophysical Fluid Dynamics Laboratory (GFDL) atmospheric model AM2, observed precipitation data, and four historic scenarios of land use change for 1700-2000. Our analysis suggests a net terrestrial carbon source due to land use activities from 1.1 to 1.3 GtC/a during the 1990s, where the range is due to the difference in the historic cropland distribution. This magnitude is substantially smaller than previous estimates from other models, largely due to our estimates of a secondary vegetation sink of 0.35 to 0.6 GtC/a in the 1990s and decelerating agricultural land clearing since the 1960s. For the 1990s, our estimates for the pastures' carbon flux vary from a source of 0.37 to a sink of 0.15 GtC/a, and for the croplands our model shows a carbon source of 0.6 to 0.9 GtC/a. Our process-based model suggests a smaller net deforestation source than earlier bookkeeping models because it accounts for decelerated net conversion of primary forest to agriculture and for stronger secondary vegetation regrowth in tropical regions. The overall uncertainty is likely to be higher than the range reported here because of uncertainty in the biomass recovery under changing ambient conditions, including atmospheric CO2 concentration, nutrients availability, and climate. Copyright 2009 by the American Geophysical Union.

  17. Relevance of methodological choices for accounting of land use change carbon fluxes

    Science.gov (United States)

    Pongratz, Julia; Hansis, Eberhard; Davis, Steven

    2015-04-01

    To understand and potentially steer how humans shape land-climate interactions it is important to accurately attribute greenhouse gas fluxes from land use and land cover change (LULCC) in space and time. However, such accounting of carbon fluxes from LULCC generally requires choosing from multiple options of how to attribute the fluxes to regions and to LULCC activities. Applying a newly-developed and spatially-explicit bookkeeping model, BLUE ("bookkeeping of land use emissions"), we quantify LULCC carbon fluxes and attribute them to land-use activities and countries by a range of different accounting methods. We present results with respect to a Kyoto Protocol-like ``commitment'' accounting period, using land use emissions of 2008-12 as example scenario. We assess the effect of accounting methods that vary (1) the temporal evolution of carbon stocks, (2) the state of the carbon stocks at the beginning of the period, (3) the temporal attribution of carbon fluxes during the period, and (4) treatment of LULCC fluxes that occurred prior to the beginning of the period. We show that the methodological choices result in grossly different estimates of carbon fluxes for the different attribution definitions. The global net flux in the accounting period varies between 4.3 Pg(C) uptake and 15.2 Pg(C) emissions, depending on the accounting method. Regional results show different modes of variation. This finding has implications for both political and scientific considerations: Not all methodological choices are currently specified under the UNFCCC treaties on land use, land-use change and forestry. Yet, a consistent accounting scheme is crucial to assure comparability of individual LULCC activities, quantify their relevance for the global annual carbon budget, and assess the effects of LULCC policies.

  18. Estimating California ecosystem carbon change using process model and land cover disturbance data: 1951-2000

    Science.gov (United States)

    Liu, J.; Vogelmann, J.E.; Zhu, Z.; Key, C.H.; Sleeter, B.M.; Price, D.T.; Chen, J.M.; Cochrane, M.A.; Eidenshink, J.C.; Howard, S.M.; Bliss, N.B.; Jiang, H.

    2011-01-01

    Land use change, natural disturbance, and climate change directly alter ecosystem productivity and carbon stock level. The estimation of ecosystem carbon dynamics depends on the quality of land cover change data and the effectiveness of the ecosystem models that represent the vegetation growth processes and disturbance effects. We used the Integrated Biosphere Simulator (IBIS) and a set of 30- to 60-m resolution fire and land cover change data to examine the carbon changes of California's forests, shrublands, and grasslands. Simulation results indicate that during 1951-2000, the net primary productivity (NPP) increased by 7%, from 72.2 to 77.1TgCyr-1 (1 teragram=1012g), mainly due to CO2 fertilization, since the climate hardly changed during this period. Similarly, heterotrophic respiration increased by 5%, from 69.4 to 73.1TgCyr-1, mainly due to increased forest soil carbon and temperature. Net ecosystem production (NEP) was highly variable in the 50-year period but on average equalled 3.0TgCyr-1 (total of 149TgC). As with NEP, the net biome production (NBP) was also highly variable but averaged -0.55TgCyr-1 (total of -27.3TgC) because NBP in the 1980s was very low (-5.34TgCyr-1). During the study period, a total of 126Tg carbon were removed by logging and land use change, and 50Tg carbon were directly removed by wildland fires. For carbon pools, the estimated total living upper canopy (tree) biomass decreased from 928 to 834TgC, and the understory (including shrub and grass) biomass increased from 59 to 63TgC. Soil carbon and dead biomass carbon increased from 1136 to 1197TgC. Our analyses suggest that both natural and human processes have significant influence on the carbon change in California. During 1951-2000, climate interannual variability was the key driving force for the large interannual changes of ecosystem carbon source and sink at the state level, while logging and fire were the dominant driving forces for carbon balances in several specific

  19. CARBON SEQUESTRATION OF SURFACE MINE LANDS

    Energy Technology Data Exchange (ETDEWEB)

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2004-05-19

    The January-March 2004 Quarter was dedicated to tree planting activities in two locations in Kentucky. During year one of this project there was no available mine land to plant in the Hazard area so 107 acres were planted in the Martin county mine location. This year 120 acres was planted in the Hazard area to compensate for the prior year and an additional 57 acres was planted on Peabody properties in western Kentucky. An additional set of special plots were established on each of these areas that contained 4800 seedlings each for special carbon sequestration determinations. Plantings were also conducted to continue compaction and water quality studies on two newly established areas as well as confirmed measurements on the first years plantings. Total plantings on this project now amount to 357 acres containing 245,960 tree seedlings.

  20. Global Tree Cover and Biomass Carbon on Agricultural Land

    NARCIS (Netherlands)

    Zomer, Robert J.; Neufeldt, Henry; Xu, Jianchu; Ahrends, Antje; Bossio, Deborah; Trabucco, Antonio; Noordwijk, Van Meine; Wang, Mingcheng

    2016-01-01

    Agroforestry systems and tree cover on agricultural land make an important contribution to climate change mitigation, but are not systematically accounted for in either global carbon budgets or national carbon accounting. This paper assesses the role of trees on agricultural land and their signif

  1. Net coal thickness in the Johnson-107 coal zone, South Carbon coalfield, Wyoming (sccat)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This ArcView shapefile contains a representation of the Johnson-107 coal zone net coal thickness. The Johnson-107 coal zone is in the South Carbon coalfield in the...

  2. The spatio-temporal responses of the carbon cycle to climate and land use/land cover changes between 1981-2000 in China

    Institute of Scientific and Technical Information of China (English)

    Zhiqiang GAO; Xiaoming CAO; Wei GAO

    2013-01-01

    This paper represents the first national effort of its kind to systematically investigate the impact of changes in climate and land use and land cover (LULC) on the carbon cycle with high-resolution dynamic LULC data at the decadal scale (1990s and 2000s).Based on simulations using well calibrated and validated Carbon Exchanges in the Vegetation-Soil-Atmosphere (CEVSA) model,temporal and spatial variations in carbon storage and fluxes in China may be generated empower us to relate these variations to climate variability and LULC with respect to net primary productivity (NPP),heterotrophic respiration (HR),net ecosystem productivity (NEP),storage and soil carbon (SOC),and vegetation carbon (VEGC) individually or collectively.Overall,the increases in NPP were greater than HR in most cases due to the effect of global warming with more precipitation in China from 1981 to 2000.With this trend,the NEP remained positive during that period,resulting in a net increase of total amount of carbon being stored by about 0.296 PgC within a 20-year time frame.Because the climate effect was much greater than that of changes of LULC,the total carbon storage in China actually increased by about 0.17 PgC within the 20-year time period.Such findings will contribute to the generation of carbon emissions control policies under global climate change impacts.

  3. Reconciling Top Down and Bottom Up Approaches to Understand Land Carbon Cycle Variability

    Science.gov (United States)

    Collatz, G. J.; Gurney, K. R.; Denning, A. S.; Randerson, J. T.; van der Werf, G. R.

    2004-12-01

    Cycle Variability Two fundamentally different approaches for estimating global carbon sources and sinks have been used over the past 15 years. The so-called "Top-down" approach involves analysis of atmospheric composition and often includes inversions of atmospheric transport. Bottom-up approaches, on the other hand, involve using carbon cycle process models driven by various observational data. Reconciling the results of these two approaches can provide powerful constraints on each but is challenging because of the large uncertainties in atmospheric measurements and transport and in our understanding of the processes controlling biogeochemical cycling of carbon. Recently, the Atmospheric Carbon Inversion Intercomparison (TransCom 3) completed mean seasonal cycle and interannual variability inversions using 12 transport models. Their results include predictions of biogeochemically driven net carbon fluxes with associated uncertainties for the globe divided into 22 regions, half of which are land regions. The cyclo-stationary inversions predicted the mean seasonal cycle as well as the mean sink/source of each region. The interannual inversions predicted the interannual variability in the sources and sinks for each region between 1980 and 2000. This study describes an analysis of the processes controlling biogeochemically driven net carbon fluxes over the seasonal cycle for each of the Transcom land regions. The processes considered are those included in the CASA biogeochemical model. The seasonally variable model inputs include NDVI, temperature, precipitation and solar radiation and burned area. The contributions of NPP, heterotrophic respiration and fire season to the seasonal cycle are evaluated for each of the 11 TransCom 3 land regions. We prescribed plausible scenarios in the biogeochemical model to evaluate the mechanisms responsible for the size and seasonality of the mean annual carbon sinks reported by TransCom 3. Initial results will also be presented for

  4. Net carbon exchange across the Arctic tundra-boreal forest transition in Alaska 1981-2000

    Science.gov (United States)

    Thompson, Catharine Copass; McGuire, A.D.; Clein, J.S.; Chapin, F. S.; Beringer, J.

    2006-01-01

    Shifts in the carbon balance of high-latitude ecosystems could result from differential responses of vegetation and soil processes to changing moisture and temperature regimes and to a lengthening of the growing season. Although shrub expansion and northward movement of treeline should increase carbon inputs, the effects of these vegetation changes on net carbon exchange have not been evaluated. We selected low shrub, tall shrub, and forest tundra sites near treeline in northwestern Alaska, representing the major structural transitions expected in response to warming. In these sites, we measured aboveground net primary production (ANPP) and vegetation and soil carbon and nitrogen pools, and used these data to parameterize the Terrestrial Ecosystem Model. We simulated the response of carbon balance components to air temperature and precipitation trends during 1981-2000. In areas experiencing warmer and dryer conditions, Net Primary Production (NPP) decreased and heterotrophic respiration (R H ) increased, leading to a decrease in Net Ecosystem Production (NEP). In warmer and wetter conditions NPP increased, but the response was exceeded by an increase in R H ; therefore, NEP also decreased. Lastly, in colder and wetter regions, the increase in NPP exceeded a small decline in R H , leading to an increase in NEP. The net effect for the region was a slight gain in ecosystem carbon storage over the 20 year period. This research highlights the potential importance of spatial variability in ecosystem responses to climate change in assessing the response of carbon storage in northern Alaska over the last two decades. ?? Springer 2005.

  5. Impacts of climate and land use change on ecosystem hydrology and net primary productivity: Linking water availability to food security in Asia

    Science.gov (United States)

    Dangal, S. R. S.; Tian, H.; Pan, S.; Zhang, B.; Yang, J.

    2015-12-01

    The nexus approach to food, water and energy security in Asia is extremely important and relevant as the region has to feed two-third of the world's population and accounts for 59% of the global water consumption. The distribution pattern of food, water and energy resources have been shaped by the legacy effect of both natural and anthropogenic disturbances and therefore are vulnerable to climate change and human activities including land use/cover change (LUCC) and land management (irrigation and nitrogen fertilization). In this study, we used the Dynamic Land Ecosystem Model (DLEM) to examine the effects of climate change, land use/cover change, and land management practices (irrigation and nitrogen fertilization) on the spatiotemporal trends and variability in water availability and its role in limiting net primary productivity (NPP) and food security in the 20th and early 21st centuries. Our specific objectives are to quantify how climate change, LUCC and other environmental changes have interactively affected carbon and water dynamics across the Asian region. In particular, we separated the Asian region into several sub-region based on the primary limiting factor - water, food and energy. We then quantified how changes in environmental factors have altered the water and food resources during the past century. We particularly focused on Net Primary Productivity (NPP) and water cycle (Evapotranspiration, discharge, and runoff) as a measure of available food and water resources, respectively while understanding the linkage between food and water resources in Asia.

  6. Soil carbon vulnerability to land-cover change and implications for the global carbon cycle

    Science.gov (United States)

    Georgiou, K.; Abramoff, R. Z.; Koven, C.; Riley, W. J.; Torn, M. S.

    2015-12-01

    Soil is a major reservoir of carbon (C) that contains more than three times the C in vegetation. While the terrestrial biosphere acts as a sink for approximately 2.5 petagrams C per year (PgC/yr) - equivalent to about 25% of fossil fuel emissions - anthropogenic land-use change reduces the global net land C sink by approximately 1 PgC/yr. Although most assessments of land-use focus on changes in aboveground biomass C, changes to 'live C' (above- and below-ground plant biomass) drive lagged, yet substantial, changes to 'dead C' (soil, dead wood, and litter) storage, with important implications for the overall land C balance. Here we provide an observation- and model-based assessment of the impacts of land-cover change on total C stocks (live and dead C) over the last decade and the potential for long-term soil C storage or loss. We find that afforestation in northern latitudes counteracts deforestation in the tropics, due in part to the greater soil C content of boreal and temperate forests. Deriving geospatial estimates of the steady-state ratio of dead to live C and the turnover time of dead C, we demonstrate that, although many recent studies have focused on forests, non-forest ecosystems (particularly shrublands and savannahs) may be responsible for larger changes in total C stocks in response to changes in C input rates due to their high soil C content. Furthermore, we disaggregate our geospatial predictions by biome and explore the depth-resolved vulnerability of soil C globally, with particular focus on the covariation of soil C sensitivity with soil properties and climate. Our findings suggest that the response of soil to changes in plant inputs significantly contributes to regional and global C budgets.

  7. Carbon consequences and agricultural implications of growing biofuel crops on marginal agricultural lands in China.

    Science.gov (United States)

    Qin, Zhangcai; Zhuang, Qianlai; Zhu, Xudong; Cai, Ximing; Zhang, Xiao

    2011-12-15

    Using marginal agricultural lands to grow energy crops for biofuel feedstocks is a promising option to meet the biofuel needs in populous China without causing further food shortages or environmental problems. Here we quantify the effects of growing switchgrass and Miscanthus on Chinese marginal agricultural lands on biomass production and carbon emissions with a global-scale biogeochemical model. We find that the national net primary production (NPP) of these two biofuel crops are 622 and 1546 g C m(-2) yr(-1), respectively, whereas the NPP of food crops is about 600 g C m(-2) yr(-1) in China. The net carbon sink over the 47 Mha of marginal agricultural lands across China is 2.1 Tg C yr(-1) for switchgrass and 5.0 Tg C yr(-1) for Miscanthus. Soil organic carbon is estimated to be 10 kg C m(-2) in both biofuel ecosystems, which is equal to the soil carbon levels of grasslands in China. In order to reach the goal of 12.5 billion liters of bioethanol in 2020 using crop biomass as biofuel feedstocks, 7.9-8.0 Mha corn grain, 4.3-6.1 Mha switchgrass, or 1.4-2.0 Mha Miscanthus will be needed. Miscanthus has tremendous potential to meet future biofuel needs, and to benefit CO(2) mitigation in China.

  8. Carbon dynamics of land use in Great Britain

    Energy Technology Data Exchange (ETDEWEB)

    Adger, W.N.; Brown, K.; Shiel, R.S.; Whitby, M.C. (East Anglia Univ., Norwich (United Kingdom). Centre for Social and Economic Research on the Global Environment)

    1992-10-01

    Aggregate yearly carbon fluctuations from 20 categories of land use are calculated and presented for groupings of these categories by estimating biomass carbon changes in the vegetation associated with the land use category and soil carbon changes for soil types associated with the same land use categories. The results are then compared with an aggregate carbon balance for the land-using sector for one year, by estimating carbon fixations and emissions from agricultural and forestry activities. The results show that conversion of land to arable cultivation leads to medium-term reductions in soil and biomass carbon, when the limits of the study are set to count agricultural and forestry products leaving the sector as having been fixed by that sector. Forestry in the period studied has not fixed large amounts of carbon because new planting initially causes losses of previously fixed biomass and soil carbon. The aggregate estimates of carbon sequestration are critically dependent on the boundaries of the study, but the estimates are still relatively minor in relation to total carbon emissions from other sectors of the economy in Great Britain. 31 refs., 9 tabs.

  9. Carbon Storage in Mountain Land Use Systems in Northern Thailand

    Directory of Open Access Journals (Sweden)

    Narit Yimyam

    2016-05-01

    Full Text Available Conversion of forested land for agriculture has obvious detrimental effects on its ecological functions, but these effects are not uniform. Mountain land use systems are diverse, encompassing managed forests and cultivated land. This study examined land use systems in 3 mountain villages in northern Thailand with different patterns of cultivation and evaluated the amount of carbon they have accumulated. Land use and management by individual farmers and communities were determined by interviews, field verification, and mapping. Biomass carbon in trees was determined nondestructively, and carbon in ground cover, litter, and soil organic matter was determined by chemical analysis of replicated samples. The 3 villages, with access to land ranging from 1.3 to 6.3 ha per capita, managed largely pristine headwater forests for security of water supply and made a living from crop production supplemented by harvests of timber, firewood, and other forest products from managed community forests. Cultivated land varied in composition and management among the villages, from shifting cultivation with fallow periods of different lengths to permanent cultivation of food and commercial crops. Per capita carbon storage in the villages well exceeded average per capita carbon dioxide emissions in Thailand, with most of the carbon stored in the forests. This has important implications for programs that offer incentives to mountain villages to maintain or enhance their carbon storage, such as the United Nations’ REDD (Reducing Emissions from Deforestation and Forest Degradation program.

  10. Energy Consumption and Net CO2 Sequestration of Aqueous Mineral Carbonation

    NARCIS (Netherlands)

    Huijgen, W.J.J.; Comans, R.N.J.; Witkamp, G.J.; Ruijg, G.J.

    2006-01-01

    Aqueous mineral carbonation is a potentially attractive sequestration technology to reduce CO2 emissions. The energy consumption of this technology, however, reduces the net amount of CO2 sequestered. Therefore, the energetic CO2 sequestration efficiency of aqueous mineral carbonation was studied in

  11. Energy Consumption and Net CO2 Sequestration of Aqueous Mineral Carbonation

    NARCIS (Netherlands)

    Huijgen, W.J.J.; Comans, R.N.J.; Witkamp, G.J.; Ruijg, G.J.

    2006-01-01

    Aqueous mineral carbonation is a potentially attractive sequestration technology to reduce CO2 emissions. The energy consumption of this technology, however, reduces the net amount of CO2 sequestered. Therefore, the energetic CO2 sequestration efficiency of aqueous mineral carbonation was studied in

  12. Systematically variable planktonic carbon metabolism along a land-to-lake gradient in a Great Lakes coastal zone.

    Science.gov (United States)

    Weinke, Anthony D; Kendall, Scott T; Kroll, Daniel J; Strickler, Eric A; Weinert, Maggie E; Holcomb, Thomas M; Defore, Angela A; Dila, Deborah K; Snider, Michael J; Gereaux, Leon C; Biddanda, Bopaiah A

    2014-11-01

    During the summers of 2002-2013, we measured rates of carbon metabolism in surface waters of six sites across a land-to-lake gradient from the upstream end of drowned river-mouth Muskegon Lake (ML) (freshwater estuary) to 19 km offshore in Lake Michigan (LM) (a Great Lake). Despite considerable inter-year variability, the average rates of gross production (GP), respiration (R) and net production (NP) across ML (604 ± 58, 222 ± 22 and 381 ± 52 µg C L(-1) day(-1), respectively) decreased steeply in the furthest offshore LM site (22 ± 3, 55 ± 17 and -33 ± 15 µg C L(-1)day(-1), respectively). Along this land-to-lake gradient, GP decreased by 96 ± 1%, whereas R only decreased by 75 ± 9%, variably influencing the carbon balance along this coastal zone. All ML sites were consistently net autotrophic (mean GP:R = 2.7), while the furthest offshore LM site was net heterotrophic (mean GP:R = 0.4). Our study suggests that pelagic waters of this Great Lakes coastal estuary are net carbon sinks that transition into net carbon sources offshore. Reactive and dynamic estuarine coastal zones everywhere may contribute similarly to regional and global carbon cycles.

  13. Systematically variable planktonic carbon metabolism along a land-to-lake gradient in a Great Lakes coastal zone

    Science.gov (United States)

    Weinke, Anthony D.; Kendall, Scott T.; Kroll, Daniel J.; Strickler, Eric A.; Weinert, Maggie E.; Holcomb, Thomas M.; Defore, Angela A.; Dila, Deborah K.; Snider, Michael J.; Gereaux, Leon C.; Biddanda, Bopaiah A.

    2014-01-01

    During the summers of 2002–2013, we measured rates of carbon metabolism in surface waters of six sites across a land-to-lake gradient from the upstream end of drowned river-mouth Muskegon Lake (ML) (freshwater estuary) to 19 km offshore in Lake Michigan (LM) (a Great Lake). Despite considerable inter-year variability, the average rates of gross production (GP), respiration (R) and net production (NP) across ML (604 ± 58, 222 ± 22 and 381 ± 52 µg C L−1 day−1, respectively) decreased steeply in the furthest offshore LM site (22 ± 3, 55 ± 17 and −33 ± 15 µg C L−1day−1, respectively). Along this land-to-lake gradient, GP decreased by 96 ± 1%, whereas R only decreased by 75 ± 9%, variably influencing the carbon balance along this coastal zone. All ML sites were consistently net autotrophic (mean GP:R = 2.7), while the furthest offshore LM site was net heterotrophic (mean GP:R = 0.4). Our study suggests that pelagic waters of this Great Lakes coastal estuary are net carbon sinks that transition into net carbon sources offshore. Reactive and dynamic estuarine coastal zones everywhere may contribute similarly to regional and global carbon cycles. PMID:25954055

  14. Characterization of changes in land cover and carbon storage in Northeastern China: An analysis based on Landsat TM data

    Institute of Scientific and Technical Information of China (English)

    WANG; Shaoqiang; (王绍强); TIAN; Hanqin; (田汉勤); LIU; Jiyuan; (刘纪远); ZHUANG; Dafang; (庄大方); ZHANG; Shuwen; (张树文); HU; Wenyan; (胡文言)

    2002-01-01

    We use Landsat TM time series data for the years of 1991/1992, 1995/1996 and 1999/2000 to characterize land-cover change in northeast China. With the information on land-cover change and the density of vegetation and soil carbon, we assess the potential effect of land-cover change on vegetation and soil carbon in this region. Our results show a large decrease of 2.76(104km2 in forest area and a rapid increase of 2.32(104km2 in urban area. Land-cover changes in northeast China have resulted in a potential maximum loss of 273.2 Tg C for the period of 1991-2000, with a net loss of 95.7 Tg C in vegetation and 177.5Tg C in soil. . The conversion of forests into other land-cover types could have potentially resulted in a loss of 254.6 Tg C for the study period, accounting for 68.8% of the total potential carbon loss in the northeast China. To quantify the net effect of land-cover change on carbon storage will require accounting for vegetation regrowth and soil processes. Our results also imply that forest protectionand reforestation are of critical importance to carbon sequestration in China.

  15. Accountable Accounting: Carbon-Based Management on Marginal Lands

    Directory of Open Access Journals (Sweden)

    Tara L. DiRocco

    2014-04-01

    Full Text Available Substantial discussion exists concerning the best land use options for mitigating greenhouse gas (GHG emissions on marginal land. Emissions-mitigating land use options include displacement of fossil fuels via biofuel production and afforestation. Comparing C recovery dynamics under these different options is crucial to assessing the efficacy of offset programs. In this paper, we focus on forest recovery on marginal land, and show that there is substantial inaccuracy and discrepancy in the literature concerning carbon accumulation. We find that uncertainty in carbon accumulation occurs in estimations of carbon stocks and models of carbon dynamics over time. We suggest that analyses to date have been largely unsuccessful at determining reliable trends in site recovery due to broad land use categories, a failure to consider the effect of current and post-restoration management, and problems with meta-analysis. Understanding of C recovery could be greatly improved with increased data collection on pre-restoration site quality, prior land use history, and management practices as well as increased methodological standardization. Finally, given the current and likely future uncertainty in C dynamics, we recommend carbon mitigation potential should not be the only environmental service driving land use decisions on marginal lands.

  16. Wide band gap carbon allotropes: Inspired by zeolite-nets

    Science.gov (United States)

    Wei, Zhi-Jing; Zhao, Hui-Yan; Wang, Jing; Liu, Ying

    2016-10-01

    Based on the topologies proposed for zeolites, six metastable semiconductor carbon allotropes with band gaps of 2.72-3.89 eV are predicted using ab initio density functional calculations. The hardnesses of these allotropes are about 90%-94% that of diamond, indicating that they may be superhard materials. We also present simulated X-ray diffraction spectra of these new carbon allotropes to provide a basis for possible experimental observations and synthesis. These new carbon structures with a range of band gaps and with hardnesses comparable to diamond could be potential targets for the synthesis of hard and transparent materials.

  17. Estimation of net ecosystem carbon exchange for the conterminous United States by combining MODIS and AmeriFlux data

    Science.gov (United States)

    Jingfeng Xiao; Qianlai Zhuang; Dennis D. Baldocchi; Beverly E. Law; Andrew D. Richardson; Jiquan Chen; Ram Oren; Gegory Starr; Asko Noormets; Siyan Ma; Sashi B. Verma; Sonia Wharton; Steven C. Wofsy; Paul V. Bolstad; Sean P. Burns; David R. Cook; Peter S. Curtis; Bert G. Drake; Matthias Falk; MArc L. Fischer; David R. Foster; Lianhong Gu; Julian L. Hadley; David Y. Hollinger; Gabriel G. Katul; Marcy Litvak; Timothy Martin; Roser Matamala; Steve McNulty; Tilden P. Meyers; Russell K. Monson; J. William Munger; Walter C. Oechel; Kyaw Tha Paw U; Hans Peter Schmid; Russell L. Scott; Ge Sun; Andrew E. Suyker; Margaret S. Torn

    2008-01-01

    Eddy covariance flux towers provide continuous measurements of net ecosystem carbon exchange (NEE) for a wide range of climate and biome types. However, these measurements only represent the carbon fluxes at the scale of the tower footprint. To quantify the net exchange of carbon dioxide between the terrestrial biosphere and the atmosphere for regions or continents,...

  18. Eddy covariance flux measurements of net ecosystem carbon dioxide exchange from a lowland peatland flux tower network in England and Wales

    Science.gov (United States)

    Morrison, Ross; Balzter, Heiko; Burden, Annette; Callaghan, Nathan; Cumming, Alenander; Dixon, Simon; Evans, Jonathan; Kaduk, Joerg; Page, Susan; Pan, Gong; Rayment, Mark; Ridley, Luke; Rylett, Daniel; Worrall, Fred; Evans, Christopher

    2016-04-01

    Peatlands store disproportionately large amounts of soil carbon relative to other terrestrial ecosystems. Over recent decades, the large amount of carbon stored as peat has proved vulnerable to a range of land use pressures as well as the increasing impacts of climate change. In temperate Europe and elsewhere, large tracts of lowland peatland have been drained and converted to agricultural land use. Such changes have resulted in widespread losses of lowland peatland habitat, land subsidence across extensive areas and the transfer of historically accumulated soil carbon to the atmosphere as carbon dioxide (CO2). More recently, there has been growth in activities aiming to reduce these impacts through improved land management and peatland restoration. Despite a long history of productive land use and management, the magnitude and controls on greenhouse gas emissions from lowland peatland environments remain poorly quantified. Here, results of surface-atmosphere measurements of net ecosystem CO2 exchange (NEE) from a network of seven eddy covariance (EC) flux towers located at a range of lowland peatland ecosystems across the United Kingdom (UK) are presented. This spatially-dense peatland flux tower network forms part of a wider observation programme aiming to quantify carbon, water and greenhouse gas balances for lowland peatlands across the UK. EC measurements totalling over seventeen site years were obtained at sites exhibiting large differences in vegetation cover, hydrological functioning and land management. The sites in the network show remarkable spatial and temporal variability in NEE. Across sites, annual NEE ranged from a net sink of -194 ±38 g CO2-C m-2 yr-1 to a net source of 784±70 g CO2-C m-2 yr-1. The results suggest that semi-natural sites remain net sinks for atmospheric CO2. Sites that are drained for intensive agricultural production range from a small net sink to the largest observed source for atmospheric CO2 within the flux tower network

  19. Contributions of biogenic volatile organic compounds to net ecosystem carbon flux in a ponderosa pine plantation

    Science.gov (United States)

    Bouvier-Brown, Nicole C.; Schade, Gunnar W.; Misson, Laurent; Lee, Anita; McKay, Megan; Goldstein, Allen H.

    2012-12-01

    When assessing net ecosystem exchange (NEE) and net ecosystem carbon balance (NECB), respiration is generally assumed to be the only significant loss of carbon to the atmosphere. However, carbon is also emitted from ecosystems in the form of biogenic volatile organic compounds (BVOCs). Here we consider the magnitude of systematic difference caused by omitting this additional carbon loss from the net ecosystem carbon balance, as compared to the NEE term, of the ponderosa pine plantation at Blodgett Forest. We find that 9.4 (range 6.2-12.5) g C m-2 yr-1 were emitted from this ecosystem as BVOCs. This is 4.0 (2.0-7.9) % of annual NEE, and neglecting this additional loss of carbon causes an overestimation of carbon storage for this rapidly growing commercial forest plantation. For ecosystems that are not storing carbon as rapidly, where photosynthesis and respiration are more closely balanced, ignoring BVOC emission may cause a larger error in the estimation of NECB.

  20. Response of land carbon cycle to stratospheric aerosol geoengineering

    Science.gov (United States)

    Zhang, Q.; Ji, D.

    2016-12-01

    Stabilizing the climate through geoengineering aims to mitigate the climate change induced by increasing atmospheric CO2 and other green house gases. These impacts in climate affect terrestrial ecosystem considerably because terrestrial carbon fluxes are sensitivity to climate change. Here we analyzed the responses of land carbon cycle to GeoMIP G4 experiment from six Earth System Models (ESMs), in which negative radiative forcing is produced by an injection of SO2 into the stratosphere to compensate the global warming in RCP4.5. From the year 2020 to 2090, there was an increase in land carbon uptake with significant discrepancy among models (20 PgC to 260 PgC) for both G4 and RCP4.5 scenario, due to the CO2 fertilization effect. For comparison with RCP4.5, all of the models showed higher land carbon uptakes in G4 scenario (30 Pg C on average), with both increases in vegetation and soil carbon stores. These land carbon increases relative to RCP4.5 are mainly resulted from reduced heterotrophic respiration under cooler temperature, whilst changes in vegetation productivity only account a negligible part of land carbon changes. The models also varied in their sensitivities of carbon fluxes to changes in air temperature and precipitation. Partial correlation analysis shows that interannual sensitivities of NBP to temperature and precipitation increased by 2 folds in the G4 experiment, due to higher sensitivities of NPP and Rh, yet with large differences among ESMs and spatial heterogeneity. This work suggests that stratospheric aerosol engineering would have small and positive impact on land carbon uptake but could increase climate sensitivities of terrestrial carbon fluxes significantly.

  1. Impacts of Land Cover Change on the Carbon Dynamics in Indonesian Tropical Forested Wetlands- Mangroves and Peat Swamp Forests

    Science.gov (United States)

    Kauffman, J. B.; Arifanti, V. B.; Basuki, I.; Kurnianto, S.; Novita, N.; Murdiyarso, D.

    2014-12-01

    Tropical wetland forests including mangroves and lowland peat swamp forests contain among the highest carbon stocks of any ecosystem on the planet. This is largely due to the accumulation of deep organic rich soils which have been sequestering carbon for millennia. Depth of organic layers (peats) can exceed 3 m in mangrove and 10 m in the peat swamp forests. The ecosystem carbon stocks may exceed 2000 Mg/ha in mangroves and 5000 Mg/ha in peat swamp forests. Ironically, rates of deforestation of these tropical forests are among the highest in the tropics. With land cover change comes dramatic shifts in carbon stocks, net ecosystem productivity, and greenhouse gas emissions. Land cover change results in carbon losses of practically all aboveground pools as well as losses arising from soil pools. Based upon studies where we have compared stock changes due to land use the carbon emissions arising from land cover change to shrimp ponds and oil palm have ranged from 800-3000 Mg CO2e/ha. The lowered carbon sequestration rates coupled with increased or similar emissions from decomposition results in an ecosystem shift from a carbon sink to a carbon source. Clearly the large carbon stocks, high rates of deforestation, and large emissions resulting from their degradation suggest that these ecosystems should receive great consideration in climate change mitigation and adaptation strategies.

  2. Effects land surface type, land use, and land use change on aquatic-atmosphere fluxes of carbon dioxide from tropical forests and peat lands of Borneo

    Science.gov (United States)

    Oechel, W. C.; Abelleira Martínez, O.; Anshari, G.; Ikawa, H.; Lawrence, W. T.; Metz, M.; Neteler, M.; Nuriman, M.; Rocchini, D.; Zona, D.

    2011-12-01

    Tropical peat lands appear to be loosing huge amounts of carbon dioxide to the atmosphere due to patterns of land use and land use change including conversion of tropical forest peat lands to palm oil production and other agricultural endeavors and forest exploitation. Here, we look at the effect of land use patterns on the export of carbon to tropical river systems and the efflux from tropical rivers to the atmosphere. Levels of pcarbon dioxide, DOC and POC were measured in the Kapuas River, the longest river in Borneo. Patterns of land use and land use change were correlated with export rates of organic matter to the river as well as the vertical fluxes of carbon dioxide from the river and delta to the atmosphere. Land conversion of tropical forests on peat land soils to agriculture, including palm oil production, had some of the highest rates of lateral fluxes of organic carbon to the river system, and among the highest fluxes of carbon dioxide from the river to the atmosphere. This approach illustrates the utility of using a combination of methods: pcarbon dioxide measurement, water chemistry, temporal remote sensing, and modeling to understand and quantify the impact of land use change on GHG emissions from tropical peat lands. Boat based eddy covariance, developed and tested in the coastal zones of the Pacific Ocean, promises to provide a powerful addition to these approaches.

  3. Can leaf net carbon gain acclimate to keep up with global warming?

    Science.gov (United States)

    Vico, Giulia; Manzoni, Stefano; Way, Danielle; Hurry, Vaughan

    2016-04-01

    Plants are able to adjust their physiological activity to fluctuations and long-term changes in their growing environment. Nevertheless, projected increases in temperature will occur with unprecedented speed. Will global warming exceed the thermal acclimation capacity of leaves, thus reducing net CO2 assimilation? Such a reduction in net CO2 assimilation rate (Anet) in response to warming may deplete ecosystems' net primary productivity, with global impacts on the carbon cycling. Here we combine data on net photosynthetic thermal acclimation to changes in temperature with a probabilistic description of leaf temperature variability. We analytically obtain the probability distribution of the net CO2 assimilation rate as a function of species-specific leaf traits and growing conditions. Using this approach, we study the effects of mean leaf temperature and its variability on average Anet and the frequency of occurrence of sub-optimal thermal conditions. To maximize the net CO2 assimilation in warmer conditions, the thermal optimum for Anet (Topt) must track the growing temperature. Observations suggest that plants' thermal acclimation capacity is limited, so that growing temperatures cannot be tracked by the Topt. It is thus likely that net CO2 assimilation rates will decline in the future. Furthermore, for set leaf traits, large fluctuations in leaf temperature reduce average Anet and increase the frequency of occurrence of sub-optimal conditions for net CO2 assimilation.

  4. Carbon Sequestration on Surface Mine Lands

    Energy Technology Data Exchange (ETDEWEB)

    Donald Graves; Christopher Barton; Richard Sweigard; Richard Warner; Carmen Agouridis

    2006-03-31

    Since the implementation of the federal Surface Mining Control and Reclamation Act of 1977 (SMCRA) in May of 1978, many opportunities have been lost for the reforestation of surface mines in the eastern United States. Research has shown that excessive compaction of spoil material in the backfilling and grading process is the biggest impediment to the establishment of productive forests as a post-mining land use (Ashby, 1998, Burger et al., 1994, Graves et al., 2000). Stability of mine sites was a prominent concern among regulators and mine operators in the years immediately following the implementation of SMCRA. These concerns resulted in the highly compacted, flatly graded, and consequently unproductive spoils of the early post-SMCRA era. However, there is nothing in the regulations that requires mine sites to be overly compacted as long as stability is achieved. It has been cultural barriers and not regulatory barriers that have contributed to the failure of reforestation efforts under the federal law over the past 27 years. Efforts to change the perception that the federal law and regulations impede effective reforestation techniques and interfere with bond release must be implemented. Demonstration of techniques that lead to the successful reforestation of surface mines is one such method that can be used to change perceptions and protect the forest ecosystems that were indigenous to these areas prior to mining. The University of Kentucky initiated a large-scale reforestation effort to address regulatory and cultural impediments to forest reclamation in 2003. During the three years of this project 383,000 trees were planted on over 556 acres in different physiographic areas of Kentucky (Table 1, Figure 1). Species used for the project were similar to those that existed on the sites before mining was initiated (Table 2). A monitoring program was undertaken to evaluate growth and survival of the planted species as a function of spoil characteristics and

  5. Potential Carbon Negative Commercial Aviation through Land Management

    Science.gov (United States)

    Hendricks, Robert C.

    2008-01-01

    Brazilian terra preta soil and char-enhanced soil agricultural systems have demonstrated both enhanced plant biomass and crop yield and functions as a carbon sink. Similar carbon sinking has been demonstrated for both glycophyte and halophyte plants and plant roots. Within the assumption of 3.7 t-C/ha/yr soils and plant root carbon sinking, it is possible to provide carbon neutral U.S. commercial aviation using about 8.5% of U.S. arable lands. The total airline CO2 release would be offset by carbon credits for properly managed soils and plant rooting, becoming carbon neutral for carbon sequestered synjet processing. If these lands were also used to produce biomass fuel crops such as soybeans at an increased yield of 60 bu/acre (225gal/ha), they would provide over 3.15 10(exp 9) gallons biodiesel fuel. If all this fuel were refined into biojet it would provide a 16% biojet-84% synjet blend. This allows the U.S. aviation industry to become carbon negative (carbon negative commercial aviation through carbon credits). Arid land recovery could yield even greater benefits.

  6. Considering Forest and Grassland Carbon in Land Management

    Science.gov (United States)

    M. Janowiak; W.J. Connelly;   K. Dante-Wood; G.M. Domke; C. Giardina; Z. Kayler; K. Marcinkowski; T. Ontl;   C. Rodriguez-Franco; C. Swanston; C.W. Woodall; M. Buford

    2017-01-01

    Forest and grassland ecosystems in the United States play a critical role in the global carbon cycle, and land management activities influence their ability to absorb and sequester carbon. These ecosystems provide a critical regulating function, offsetting about 12 to 19 percent of the Nation’s annual greenhouse gas emissions. Forests and grasslands are managed for...

  7. An integrated approach to modeling changes in land use, land cover, and disturbance and their impact on ecosystem carbon dynamics: a case study in the Sierra Nevada Mountains of California

    Directory of Open Access Journals (Sweden)

    Benjamin M. Sleeter

    2015-06-01

    Full Text Available Increased land-use intensity (e.g. clearing of forests for cultivation, urbanization, often results in the loss of ecosystem carbon storage, while changes in productivity resulting from climate change may either help offset or exacerbate losses. However, there are large uncertainties in how land and climate systems will evolve and interact to shape future ecosystem carbon dynamics. To address this we developed the Land Use and Carbon Scenario Simulator (LUCAS to track changes in land use, land cover, land management, and disturbance, and their impact on ecosystem carbon storage and flux within a scenario-based framework. We have combined a state-and-transition simulation model (STSM of land change with a stock and flow model of carbon dynamics. Land-change projections downscaled from the Intergovernmental Panel on Climate Change’s (IPCC Special Report on Emission Scenarios (SRES were used to drive changes within the STSM, while the Integrated Biosphere Simulator (IBIS ecosystem model was used to derive input parameters for the carbon stock and flow model. The model was applied to the Sierra Nevada Mountains ecoregion in California, USA, a region prone to large wildfires and a forestry sector projected to intensify over the next century. Three scenario simulations were conducted, including a calibration scenario, a climate-change scenario, and an integrated climate- and land-change scenario. Based on results from the calibration scenario, the LUCAS age-structured carbon accounting model was able to accurately reproduce results obtained from the process-based biogeochemical model. Under the climate-only scenario, the ecoregion was projected to be a reliable net sink of carbon, however, when land use and disturbance were introduced, the ecoregion switched to become a net source. This research demonstrates how an integrated approach to carbon accounting can be used to evaluate various drivers of ecosystem carbon change in a robust, yet transparent

  8. Assessment Impacts of Weather and Land Use/Land Cover (LULC Change on Urban Vegetation Net Primary Productivity (NPP: A Case Study in Guangzhou, China

    Directory of Open Access Journals (Sweden)

    Xiantie Zeng

    2013-08-01

    Full Text Available Net primary productivity (NPP can indicate vegetation ecosystem services ability and reflect variation response to climate change and human activities. This study applied MODIS-1 km NPP products to investigate the NPP variation from 2001 to 2006, a fast urban expansion and adjustment period in Guangzhou, China, and quantify the impacts of weather and land use/land cover (LULC changes, respectively. The results showed that the NPP mean value increased at a rate of 11.6 g∙C∙m−2∙yr−1 during the initial three years and decreased at an accelerated rate of 31.0 g∙C∙m−2∙yr−1 during the final three years, resulting in a total NPP loss of approximately 167 × 106 g∙C. The spatiotemporal of NPP varied obviously in the central area, suburb and exurb of Guangzhou driven by three patterns of weather and LULC changes. By the interactive effects and the weather variation dominated effects, NPP of most areas changed slightly with dynamic index less than 5% of NPP mean value in the central area and the suburb. The LULC change dominated effects caused obvious NPP reduction, by more than 15% of the NPP mean value, which occurred in some areas of the suburb and extended to the exurb with the outward urban sprawl. Importantly, conversion from wood grassland, shrublands and even forests to croplands occupied by urban landscapes proved to be a main process in the conversion from high-NPP coverage to low-NPP coverage, thereby leading to the rapid degradation of urban carbon stock capacity in urban fringe areas. It is helpful for government to monitor urban ecological health and safety and make relevant policies.

  9. The loss of Scottish peatlands: Implications for long-term net gains in coastal Blue Carbon stocks.

    Science.gov (United States)

    Austin, William; Smeaton, Craig; Winterton, Cathy; Clarke, Jessica; Smith, Laura; Ward, Hannah; Bennett, Keith

    2016-04-01

    Nearly 66% of Scotland is covered by peat and organic soils, representing over 50% of the UK's soil carbon stocks. Peatland erosion, while partly a natural process, is also accelerated by human activities, such as land management and potentially by the impacts of climate change. We present evidence from the voes (sea lochs or fjords) of Shetland's west coast to suggest that this process may have accelerated since Medieval times. Our work is supported by the analyses of short sediment (Craib) cores (triplicate coring) recovered from 17 sites. We present preliminary chronologies supported by radiocarbon dating and sediment characteristics that highlight both changes in the rate of accumulation and source of sedimentary organic carbon to the west Shetland voes during the late Holocene. Scottish coastal sediments contain a significant Blue Carbon stock, a significant proportion of which derives directly from terrestrial sources. The loss of peatland carbon represents a potentially important contribution (i.e. net gain) in refractory carbon within the marine environment and we present preliminary estimates to assess the significance of these large-scale transfers to the coastal ocean.

  10. Effects of ozone on net primary production and carbon sequestration in the conterminous United States using a biogeochemistry model

    Science.gov (United States)

    Felzer, B.; Kicklighter, D.; Melillo, J.; Wang, C.; Zhuang, Q.; Prinn, R.

    2004-07-01

    The effects of air pollution on vegetation may provide an important control on the carbon cycle that has not yet been widely considered. Prolonged exposure to high levels of ozone, in particular, has been observed to inhibit photosynthesis by direct cellular damage within the leaves and through possible changes in stomatal conductance. We have incorporated empirical equations derived for trees (hardwoods and pines) and crops into the Terrestrial Ecosystem Model to explore the effects of ozone on net primary production (NPP) and carbon sequestration across the conterminous United States. Our results show a 2.6 6.8% mean reduction for the United States in annual NPP in response to modelled historical ozone levels during the late 1980s-early 1990s. The largest decreases (over 13% in some locations) occur in the Midwest agricultural lands, during the mid-summer when ozone levels are highest. Carbon sequestration since the 1950s has been reduced by 18 38 Tg C yr1 with the presence of ozone. Thus the effects of ozone on NPP and carbon sequestration should be factored into future calculations of the United States' carbon budget.

  11. Estimating agro-ecosystem carbon balance of northern Japan, and comparing the change in carbon stock by soil inventory and net biome productivity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xi, E-mail: icy124@hotmail.com [School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Graduate school of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo 060-8589 (Japan); Toma, Yo [Faculty of Agriculture, Ehime University, 3-5-7, Tarumi, Matsuyama 790-8566, Ehime (Japan); Yeluripati, Jagadeesh [The James Hutton Institute, Craigiebuckler, Aberdeen AB15 8QH, Scotland (United Kingdom); Iwasaki, Shinya [Graduate school of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo 060-8589 (Japan); Bellingrath-Kimura, Sonoko D. [Leibniz Centre for Agricultural Landscape Research, Institute of Land Use Systems (Germany); Jones, Edward O. [Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London (United Kingdom); Hatano, Ryusuke [Graduate school of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo 060-8589 (Japan)

    2016-06-01

    Soil C sequestration in croplands is deemed to be one of the most promising greenhouse gas mitigation options for agriculture. We have used crop-level yields, modeled heterotrophic respiration (Rh) and land use data to estimate spatio-temporal changes in regional scale net primary productivity (NPP), plant C inputs, and net biome productivity (NBP) in northern Japan's arable croplands and grasslands for the period of 1959–2011. We compared the changes in C stocks derived from estimated NBP and using repeated inventory datasets for each individual land use type from 2005 to 2011. For the entire study region of 2193 ha, overall annual plant C inputs to the soil constituted 37% of total region NPP. Plant C inputs in upland areas (excluding bush/fallow) could be predicted by climate variables. Overall NBP for all land use types increased from − 1.26 Mg C ha{sup −1} yr{sup −1} in 1959–0.26 Mg C ha{sup −1} yr{sup −1} in 2011. However, upland and paddy fields showed a decreased in NBP over the period of 1959–2011, under the current C input scenario. From 1988, an increase in agricultural abandonment (bush/fallow) and grassland cover caused a slow increase in the regional C pools. The comparison of carbon budgets using the NBP estimation method and the soil inventory method indicated no significant difference between the two methods. Our results showed C loss in upland crops, paddy fields and sites that underwent land use change from paddy field to upland sites. We also show C gain in grassland from 2005 to 2011. An underestimation of NBP or an overestimation of repeated C inventories cannot be excluded, but either method may be suitable for tracking absolute changes in soil C, considering the uncertainty associated with these methods. - Highlights: • We compared C stocks change by two methods: (i) net biome productivity (NBP) and (ii) soil inventory. • Variation in net primary productivity (NPP), plant C input, NBP can be predicted by climate

  12. Climate change - Storing carbon on land

    CSIR Research Space (South Africa)

    Scholes, RJ

    2001-11-02

    Full Text Available The terrestrial biosphere currently absorbs about a quarter of the anthropogenic carbon emissions. Can this carbon sink help to mitigate climate change? In their Perspective, the authors argue that the world will not be worse off for having...

  13. Convergent evolution towards high net carbon gain efficiency contributes to the shade tolerance of palms (Arecaceae)

    NARCIS (Netherlands)

    Ma, Ren Yi; Zhang, Jiao Lin; Cavaleri, Molly A.; Sterck, Frank; Strijk, J.S.; Cao, Kun Fang

    2015-01-01

    Most palm species occur in the shaded lower strata of tropical rain forests, but how their traits relate to shade adaptation is poorly understood. We hypothesized that palms are adapted to the shade of their native habitats by convergent evolution towards high net carbon gain efficiency (CGEn),

  14. ENHANCEMENT OF TERRESTRIAL CARBON SINKS THROUGH RECLAMATION OF ABANDONED MINE LANDS IN THE APPALACHIAN REGION

    Energy Technology Data Exchange (ETDEWEB)

    Gary D. Kronrad

    2002-12-01

    The U.S.D.I. Office of Surface Mining (OSM) estimates that there are approximately 1 million acres of abandoned mine land (AML) in the Appalachian region. AML lands are classified as areas that were inadequately reclaimed or were left unreclaimed prior to the passage of the 1977 Surface Mining Control and Reclamation Act, and where no federal or state laws require any further reclamation responsibility to any company or individual. Reclamation and afforestation of these sites have the potential to provide landowners with cyclical timber revenues, generate environmental benefits to surrounding communities, and sequester carbon in the terrestrial ecosystem. Through a memorandum of understanding, the OSM and the U.S. Department of Energy (DOE) have decided to investigate reclaiming and afforesting these lands for the purpose of mitigating the negative effects of anthropogenic carbon dioxide in the atmosphere. This study determined the carbon sequestration potential of northern red oak (Quercus rubra L.), one of the major reclamation as well as commercial species, planted on West Virginia AML sites. Analyses were conducted to (1) calculate the total number of tons that can be stored, (2) determine the cost per ton to store carbon, and (3) calculate the profitability of managing these forests for timber production alone and for timber production and carbon storage together. The Forest Management Optimizer (FORMOP) was used to simulate growth data on diameter, height, and volume for northern red oak. Variables used in this study included site indices ranging from 40 to 80 (base age 50), thinning frequencies of 0, 1, and 2, thinning percentages of 20, 25, 30, 35, and 40, and a maximum rotation length of 100 years. Real alternative rates of return (ARR) ranging from 0.5% to 12.5% were chosen for the economic analyses. A total of 769,248 thinning and harvesting combinations, net present worths, and soil expectation values were calculated in this study. Results indicate that

  15. Carbon Sequestration on Surface Mine Lands

    Energy Technology Data Exchange (ETDEWEB)

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2005-10-02

    During this quarter a general forest monitoring program was conducted to measure treatment effects on above ground and below ground carbon C and Nitrogen (N) pools for the tree planting areas. Detailed studies to address specific questions pertaining to Carbon cycling was initiated with the development of plots to examine the influence of mycorrhizae, spoil chemical and mineralogical properties, and use of amendment on forest establishment and carbon sequestration. Efforts continued during this period to examine decomposition and heterotrophic respiration on C cycling in the reforestation plots. Projected climate change resulting from elevated atmospheric carbon dioxide has given rise to various strategies to sequester carbon in various terrestrial ecosystems. Reclaimed surface mine soils present one such potential carbon sink where traditional reclamation objectives can complement carbon sequestration. New plantings required the modification and design and installation on monitoring equipment. Maintenance and data monitoring on past and present installations are a continuing operation. The Department of Mining Engineering continued the collection of penetration resistance, penetration depth, and bulk density on both old and new treatment areas. Data processing and analysis is in process for these variables. Project scientists and graduate students continue to present results at scientific meetings, tours and field days presentations of the research areas are being conducted on a request basis.

  16. Anthropogenic perturbation of the carbon fluxes from land to ocean

    KAUST Repository

    Regnier, Pierre

    2013-06-09

    A substantial amount of the atmospheric carbon taken up on land through photosynthesis and chemical weathering is transported laterally along the aquatic continuum from upland terrestrial ecosystems to the ocean. So far, global carbon budget estimates have implicitly assumed that the transformation and lateral transport of carbon along this aquatic continuum has remained unchanged since pre-industrial times. A synthesis of published work reveals the magnitude of present-day lateral carbon fluxes from land to ocean, and the extent to which human activities have altered these fluxes. We show that anthropogenic perturbation may have increased the flux of carbon to inland waters by as much as 1.0 Pg C yr -1 since pre-industrial times, mainly owing to enhanced carbon export from soils. Most of this additional carbon input to upstream rivers is either emitted back to the atmosphere as carbon dioxide (∼0.4 Pg C yr -1) or sequestered in sediments (∼0.5 Pg C yr -1) along the continuum of freshwater bodies, estuaries and coastal waters, leaving only a perturbation carbon input of ∼0.1 Pg C yr -1 to the open ocean. According to our analysis, terrestrial ecosystems store ∼0.9 Pg C yr -1 at present, which is in agreement with results from forest inventories but significantly differs from the figure of 1.5 Pg C yr -1 previously estimated when ignoring changes in lateral carbon fluxes. We suggest that carbon fluxes along the land-ocean aquatic continuum need to be included in global carbon dioxide budgets.

  17. CARBON SEQUESTRATION ON SURFACE MINE LANDS

    Energy Technology Data Exchange (ETDEWEB)

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2004-11-30

    A monitoring program to measure treatment effects on above ground, and below ground carbon and nitrogen pools for the planting areas is being conducted. The collection of soil and tissue samples from both the 2003 and 2004 plantings is complete and are currently being processed in the laboratory. Detailed studies have been initiated to address specific questions pertaining to carbon cycling. Examinations of decomposition and heterotropic respiration on carbon cycling in the reforestation plots were continued during this reporting period. A whole-tree harvesting method was employed to evaluate carbon accumulation as a function of time on the mined site. The trees were extracted from the sites and separated into the following components: foliage, stems, branches, and roots.

  18. A Terrestrial Ecosystem Full Verified Carbon Accounting for Russian Land: Results and Uncertainty

    Science.gov (United States)

    Shvidenko, A.; Schepaschenko, D.; Maksyutov, S.

    2010-12-01

    We present a terrestrial full carbon account (FCA) for Russian land in a spatially explicit form for 2009 and aggregated country-wide annual estimates for 2004-2008. The integrated methodology of the FCA takes into account the fuzzy character of the studied systems. IIASA’s landscape-ecosystem approach (LEA) is used for designing the account boundaries and assessment of major pools and fluxes. An Integrated Land Information System (ILIS) serves as the information background of the FCA. The ILIS is based on a system integration of all available ground data and multi-sensor remote sensing applications. The ILIS includes a georeferenced hybrid land cover (~500 land classes, resolution 1 x 1 km), corresponding attributive datasets and sets of empirical and semi-empirical ecosystem and landscape models. The latter are based on long-period measurements of ecological parameters with corrections - if necessary - due to weather specifics of individual growth seasons. On average, terrestrial ecosystems of Russia served as a sink of roughly 0.6 Pg C yr-1 during the last five years which exceeds the technosphere’s emissions of the country by about one third. Two major fluxes (net primary production and heterotrophic respiration) for all productive lands of the country are estimated at 323 and 204 g C yr-1 m-2, respectively. Disturbance and consumption of plant products comprise from 15 to 20% of the net primary production. Forests serve as a major component of the sink (~85% of the country’s total). Disturbed forests and peatlands, as well as cultivated agricultural lands, are a relatively small carbon source. The interannual variability of the net ecosystem carbon balance are mostly driven by climatic conditions and natural disturbance (fire, insects) of the growth periods and is in limits of 10-15% for the country as a whole, but could exceed 25-30% for large regions with weather anomalies of the vegetation periods. Uncertainty within the LEA was assessed for all

  19. Tropical Africa: Land use, biomass, and carbon estimates for 1980

    Energy Technology Data Exchange (ETDEWEB)

    Brown, S. [Environmental Protection Agency, Corvallis, OR (United States). Western Ecology Division; Gaston, G. [Environmental Protection Agency, Corvallis, OR (United States). National Research Council; Daniels, R.C. [ed.] [Oak Ridge National Lab., TN (United States)

    1996-06-01

    This document describes the contents of a digital database containing maximum potential aboveground biomass, land use, and estimated biomass and carbon data for 1980 and describes a methodology that may be used to extend this data set to 1990 and beyond based on population and land cover data. The biomass data and carbon estimates are for woody vegetation in Tropical Africa. These data were collected to reduce the uncertainty associated with the possible magnitude of historical releases of carbon from land use change. Tropical Africa is defined here as encompassing 22.7 x 10{sup 6} km{sup 2} of the earth`s land surface and includes those countries that for the most part are located in Tropical Africa. Countries bordering the Mediterranean Sea and in southern Africa (i.e., Egypt, Libya, Tunisia, Algeria, Morocco, South Africa, Lesotho, Swaziland, and Western Sahara) have maximum potential biomass and land cover information but do not have biomass or carbon estimate. The database was developed using the GRID module in the ARC/INFO{sup TM} geographic information system. Source data were obtained from the Food and Agriculture Organization (FAO), the U.S. National Geophysical Data Center, and a limited number of biomass-carbon density case studies. These data were used to derive the maximum potential and actual (ca. 1980) aboveground biomass-carbon values at regional and country levels. The land-use data provided were derived from a vegetation map originally produced for the FAO by the International Institute of Vegetation Mapping, Toulouse, France.

  20. Ocean acidification accelerates net calcium carbonate loss in a coral rubble community

    Science.gov (United States)

    Stubler, Amber D.; Peterson, Bradley J.

    2016-09-01

    Coral rubble communities are an important yet often overlooked component of a healthy reef ecosystem. The organisms inhabiting reef rubble are primarily bioeroders that contribute to the breakdown and dissolution of carbonate material. While the effects of ocean acidification on calcifying communities have been well studied, there are few studies investigating the response of bioeroding communities to future changes in pH and calcium carbonate saturation state. Using a flow-through pH-stat system, coral rubble pieces with a naturally occurring suite of organisms, along with bleached control rubble pieces, were subjected to three different levels of acidification over an 8-week period. Rates of net carbonate loss in bleached control rubble doubled in the acidification treatments (0.02 vs. 0.04% CaCO3 d-1 in ambient vs. moderate and high acidification), and living rubble communities experienced significantly increased rates of net carbonate loss from ambient to high acidification conditions (0.06 vs. 0.10% CaCO3 d-1, respectively). Although more experimentation is necessary to understand the long-term response and succession of coral rubble communities under projected conditions, these results suggest that rates of carbonate loss will increase in coral rubble as pH and calcium carbonate saturation states are reduced. This study demonstrates a need to thoroughly investigate the contribution of coral rubble to the overall carbonate budget, reef resilience, recovery, and function under future conditions.

  1. The Chinese Grain for Green Programme: assessing the carbon sequestered via land reform.

    Science.gov (United States)

    Persson, Martin; Moberg, Jesper; Ostwald, Madelene; Xu, Jintao

    2013-09-15

    The Grain for Green Programme (GGP) was launched in China in 1999 to control erosion and increase vegetation cover. Budgeted at USD 40 billion, GGP has converted over 20 million hectares of cropland and barren land into primarily tree-based plantations. Although GGP includes energy forests, only a negligible part (0.6%) is planted as such, most of the land (78%) being converted for protection. Future use of these plantations is unclear and an energy substitution hypothesis is valid. We estimate the overall carbon sequestration via GGP using official statistics and three approaches, based on i) net primary production, ii) IPCC's greenhouse gas inventory guidelines, and iii) mean annual increment. We highlight uncertainties associated with GGP and the estimates. Results indicate that crop- and barren-land conversion sequestered 222-468 Mt of carbon over GGP's first ten years, the IPCC approach yielding the highest estimate and the other two approaches yielding similar but lower estimates (approximately 250 Mt of carbon). The carbon stock in these plantation systems yields a mean of 12.3 t of carbon per hectare. Assessment uncertainties concern the use of growth curves not designed for particular species and locations, actual plantation survival rates, and discrepancies in GGP figures (e.g., area, type, and survival rate) at different authority levels (from national to local). The carbon sequestered in above- and below-ground biomass from GGP represents 14% (based on the median of the three approaches) of China's yearly (2009) carbon dioxide emissions from fossil fuel use and cement production.

  2. Spatiotemporal Variability of Carbon Flux from Different Land Use and Land Cover Changes: A Case Study in Hubei Province, China

    Directory of Open Access Journals (Sweden)

    Li Gao

    2014-04-01

    Full Text Available Carbon sources and sinks as a result of land use and land cover changes (LUCC are significant for global climate change. This paper aims to identify and analyze the temporal and spatial changes of land use-based carbon emission in the Hubei Province in China. We use a carbon emission coefficient to calculate carbon emissions in different land use patterns in Hubei Province from 1998 to 2009. The results indicate that regional land use is facing tremendous pressure from rapid carbon emission growth. Source:sink ratios and average carbon emission intensity values of urban land are increasing, while slow-growing carbon sinks fail to offset the rapidly expanding carbon sources. Overall, urban land carbon emissions have a strong correlation with the total carbon emissions, and will continue to increase in the future mainly due to the surge of industrialization and urbanization. Furthermore, carbon emission in regions with more developed industrial structures is much higher than in regions with less advanced industrial structures. Lastly, carbon emission per unit of GDP has declined since 2004, indicating that a series of reform measures i.e., economic growth mode transformation and land-use structure optimization, has initiated the process of carbon emission reduction.

  3. Carbon offsets and land use in the brazilian Amazon

    Energy Technology Data Exchange (ETDEWEB)

    Del Carmen Vera Diaz, M. [Boston University, Boston (United States); Schwartzman, S. [Environmental Defense, Washington DC (United States)

    2005-07-01

    Reducing tropical deforestation will be central to an effective international carbon emissions control regime. The 'compensated reduction' concept proposes a voluntary mechanism for tropical countries to receive compensation for demonstrated reductions of deforestation below a national baseline through international carbon markets. Two questions arise in examining ways to implement this concept. First, is carbon economically competitive with current land uses in tropical regions? If so, what effects on carbon markets would carbon crediting for reduced deforestation be liable to produce, that is, what volume of carbon would likely be available for sale? This paper addresses these two issues in the case of the largest remaining tropical forest region in the world, the Brazilian Amazon.

  4. Development of an ensemble-adjoint optimization approach to derive uncertainties in net carbon fluxes

    Directory of Open Access Journals (Sweden)

    T. Ziehn

    2011-11-01

    Full Text Available Accurate modelling of the carbon cycle strongly depends on the parametrization of its underlying processes. The Carbon Cycle Data Assimilation System (CCDAS can be used as an estimator algorithm to derive posterior parameter values and uncertainties for the Biosphere Energy Transfer and Hydrology scheme (BETHY. However, the simultaneous optimization of all process parameters can be challenging, due to the complexity and non-linearity of the BETHY model. Therefore, we propose a new concept that uses ensemble runs and the adjoint optimization approach of CCDAS to derive the full probability density function (PDF for posterior soil carbon parameters and the net carbon flux at the global scale. This method allows us to optimize only those parameters that can be constrained best by atmospheric carbon dioxide (CO2 data. The prior uncertainties of the remaining parameters are included in a consistent way through ensemble runs, but are not constrained by data. The final PDF for the optimized parameters and the net carbon flux are then derived by superimposing the individual PDFs for each ensemble member. We find that the optimization with CCDAS converges much faster, due to the smaller number of processes involved. Faster convergence also gives us much increased confidence that we find the global minimum in the reduced parameter space.

  5. An ecosystem-scale perspective of the net land methanol flux: synthesis of micrometeorological flux measurements

    Directory of Open Access Journals (Sweden)

    G. Wohlfahrt

    2015-01-01

    Full Text Available Methanol is the second most abundant volatile organic compound in the troposphere and plays a significant role in atmospheric chemistry. While there is consensus about the dominant role of living plants as the major source and the reaction with OH as the major sink of methanol, global methanol budgets diverge considerably in terms of source/sink estimates reflecting uncertainties in the approaches used to model, and the empirical data used to separately constrain these terms. Here we compiled micrometeorological methanol flux data from eight different study sites and reviewed the corresponding literature in order to provide a first cross-site synthesis of the terrestrial ecosystem-scale methanol exchange and present an independent data-driven view of the land–atmosphere methanol exchange. Our study shows that the controls of plant growth on the production, and thus the methanol emission magnitude, and stomatal conductance on the hourly methanol emission variability, established at the leaf level, hold across sites at the ecosystem-level. Unequivocal evidence for bi-directional methanol exchange at the ecosystem scale is presented. Deposition, which at some sites even exceeds methanol emissions, represents an emerging feature of ecosystem-scale measurements and is likely related to environmental factors favouring the formation of surface wetness. Methanol may adsorb to or dissolve in this surface water and eventually be chemically or biologically removed from it. Management activities in agriculture and forestry are shown to increase local methanol emission by orders of magnitude; they are however neglected at present in global budgets. While contemporary net land methanol budgets are overall consistent with the grand mean of the micrometeorological methanol flux measurements, we caution that the present approach of simulating methanol emission and deposition separately is prone to opposing systematic errors and does not allow taking full

  6. Global Network Enterprise Construct (GNEC): The Army’s Strategic Vision for the Transformation of LandWarNet

    Science.gov (United States)

    2010-07-10

    activities, increased LandWarNet security, and synchronized capabili- ties delivery. Information Technology Service Management ( ITSM ) is the management...business objectives in an optimally cost effective manner. ITSM is an all-inclusive, holis- tic approach to managing IT components, processes, and ser...vices Army-wide. The focus of the Army CIO/G-6 IE Strategy is enterprise ITSM — People, Processes and Technology — that improves the Army’s ability to

  7. PALADYN, a comprehensive land surface-vegetation-carbon cycle model of intermediate complexity

    Science.gov (United States)

    Willeit, Matteo; Ganopolski, Andrey

    2016-04-01

    PALADYN is presented, a new comprehensive and computationally efficient land surface-vegetation-carbon cycle model designed to be used in Earth system models of intermediate complexity for long-term simulations and paleoclimate studies. The model treats in a consistent manner the interaction between atmosphere, terrestrial vegetation and soil through the fluxes of energy, water and carbon. Energy, water and carbon are conserved. The model explicitly treats permafrost, both in physical processes and as important carbon pool. The model distinguishes 9 surface types of which 5 are different vegetation types, bare soil, land ice, lake and ocean shelf. Including the ocean shelf allows to treat continuous changes in sea level and shelf area associated with glacial cycles. Over each surface type the model solves the surface energy balance and computes the fluxes of sensible, latent and ground heat and upward shortwave and longwave radiation. It includes a single snow layer. The soil model distinguishes between three different macro surface types which have their own soil column: vegetation and bare soil, ice sheet and ocean shelf. The soil is vertically discretized into 5 layers where prognostic equations for temperature, water and carbon are consistently solved. Phase changes of water in the soil are explicitly considered. A surface hydrology module computes precipitation interception by vegetation, surface runoff and soil infiltration. The soil water equation is based on Darcy's law. Given soil water content, the wetland fraction is computed based on a topographic index. Photosynthesis is computed using a light use efficiency model. Carbon assimilation by vegetation is coupled to the transpiration of water through stomatal conductance. The model includes a dynamic vegetation module with 5 plant functional types competing for the gridcell share with their respective net primary productivity. Each macro surface type has its own carbon pools represented by a litter, a fast

  8. Multi-year net ecosystem carbon balance at a horticulture-extracted restored peatland

    Science.gov (United States)

    Nugent, Kelly; Strachan, Ian; Strack, Maria

    2017-04-01

    Restoration of previously extracted peatlands is essential to minimize the impact of drainage and peat removal. Best practices restoration methods have been developed that include ditch blocking, site leveling and reintroducing bog vegetation using the moss layer transfer technique. A long term goal of restoration is the return to a peat accumulating ecosystem. Bois-des-Bel is a cool-temperate bog, located in eastern Quebec, Canada, that was vacuum harvested until 1980 and restored in 1999. While several studies have used discrete (chamber) methods to determine the net carbon exchange from rewetted or restored peatlands, ours appears to be the first to have multiple complete years of net ecosystem carbon exchange from a restored northern peatland. An eddy covariance flux tower instrumented with a sonic anemometer and open-path CO2/H2O and CH4 analyzers was operated continuously over three years to produce a robust estimate of net carbon sequestration. Our initial results indicate that this restored peatland was a consistent moderate annual net sink for CO2, a moderate source of CH4 and had low losses of dissolved organic carbon compared to undisturbed northern latitude peatlands. Closed chambers combined with a fast response CO2/H2O/CH4 analyzer were used to investigate ecohydrological controls on net ecosystem exchange of CO2 (NEE) and CH4 flux from the restored fields and remnant ditches at the site. CH4 release was found to be an order of magnitude higher in the ditches compared to the fields, with non-vegetated ditch showing a greater range in flux compared to areas invaded by Typha latifolia. Bubble magnitude and count were highest in the non-vegetated ditch, followed by Typha plots and were undetectable in the restored fields. The latter may be partially attributed to the high cover of Eriophorum vaginatum in the restored fields, plants that have aerenchymous tissue, as well as a much deeper water table level. While the non-vegetated ditch areas were a steady

  9. Carbon stewardship: land management decisions and the potential for carbon sequestration in Colorado, USA

    Science.gov (United States)

    Failey, Elisabeth L.; Dilling, Lisa

    2010-04-01

    Land use and its role in reducing greenhouse gases is a key element of policy negotiations to address climate change. Calculations of the potential for enhanced terrestrial sequestration have largely focused on the technical characteristics of carbon stocks, such as vegetation type and management regime, and to some degree, on economic incentives. However, the actual potential for carbon sequestration critically depends on who owns the land and additional land management decision drivers. US land ownership patterns are complex, and consequently land use decision making is driven by a variety of economic, social and policy incentives. These patterns and incentives make up the 'carbon stewardship landscape'—that is, the decision making context for carbon sequestration. We examine the carbon stewardship landscape in the US state of Colorado across several public and private ownership categories. Achieving the full potential for land use management to help mitigate carbon emissions requires not only technical feasibility and financial incentives, but also effective implementing mechanisms within a suite of often conflicting and hard to quantify factors such as multiple-use mandates, historical precedents, and non-monetary decision drivers.

  10. Biodiverse planting for carbon and biodiversity on indigenous land.

    Science.gov (United States)

    Renwick, Anna R; Robinson, Catherine J; Martin, Tara G; May, Tracey; Polglase, Phil; Possingham, Hugh P; Carwardine, Josie

    2014-01-01

    Carbon offset mechanisms have been established to mitigate climate change through changes in land management. Regulatory frameworks enable landowners and managers to generate saleable carbon credits on domestic and international markets. Identifying and managing the associated co-benefits and dis-benefits involved in the adoption of carbon offset projects is important for the projects to contribute to the broader goal of sustainable development and the provision of benefits to the local communities. So far it has been unclear how Indigenous communities can benefit from such initiatives. We provide a spatial analysis of the carbon and biodiversity potential of one offset method, planting biodiverse native vegetation, on Indigenous land across Australia. We discover significant potential for opportunities for Indigenous communities to achieve carbon sequestration and biodiversity goals through biodiverse plantings, largely in southern and eastern Australia, but the economic feasibility of these projects depend on carbon market assumptions. Our national scale cost-effectiveness analysis is critical to enable Indigenous communities to maximise the benefits available to them through participation in carbon offset schemes.

  11. Carbon cycling along the land to ocean continuum (Invited)

    Science.gov (United States)

    Ciais, P.; Regnier, P.; Friedlingstein, P.; Mackenzie, F. T.; Gruber, N.; Raymond, P. A.

    2013-12-01

    A fraction of atmospheric CO2 taken up on land through photosynthesis and chemical weathering is transported laterally from upland terrestrial ecosystems into the ocean. Global carbon budget estimates have assumed that the lateral transport and sources / sinks along this aquatic continuum have remained unchanged. Based upon the recent review of Regnier et al., the main flux components of carbon fluxes along the land to ocean continuum will be presented, together with more recent estimates of CO2 outgassing fluxes from rivers and lakes. The potential origin of carbon delivered to rivers will be discussed, as well as missing components in the system such as wetlands and flooded regions. How these processes could be incorporated in Earth System Models will be presented.

  12. Assessing carbon stocks and modelling win-win scenarios of carbon sequestration through land-use changes

    Energy Technology Data Exchange (ETDEWEB)

    Ponce-Hernandez, R.; Koohafkan, P.; Antoine, J. (eds.)

    2004-07-01

    This publication presents a methodology and software tools for assessing carbon stocks and modelling scenarios of carbon sequestration that were developed and tested in pilot field studies in Mexico and Cuba. The models and tools enable the analysis of land use change scenarios in order to identify in a given area (watershed or district) land use alternatives and land management practices that simultaneously maximize food production, maximize soil carbon sequestration, maximize biodiversity conservation and minimize land degradation. The objective is to develop and implement 'win-win' options that satisfy the multiple goals of farmers, land users and other stakeholders in relation to food security, carbon sequestration, biodiversity and land conservation.

  13. Carbon Emission Effect of Land Use in Nanchang City and Its Optimization Countermeasures

    Institute of Scientific and Technical Information of China (English)

    Haisheng; CAI; Ting; ZHANG; Xueling; ZHANG

    2013-01-01

    Land use/coverage change(LUCC)exerts a profound influence on global carbon emission through changing structure and functions of ecosystem.Taking Nanchang City as an example,this study determined organic carbon emission of land ecosystem by ecosystem type method.In 2005,total carbon emission of Nanchang City was 4.826 2 Tg.In 2010,it became 5.535 9 Tg,showing a growth trend of carbon emission from land use change.The carbon emission of cropland and grassland decreased in 2005-2010,that of garden land and construction land had increase,and carbon absorption function of water land and other unused land was weakened.Due to difference of land use structure,the carbon emission of Nanchang City is varied.In 2005-2010,the rank of carbon emission from high to low is as follows:Nanchang County,Xinjian County,Jinxian County and Qingshanhu District.In combination with land use change and development plan of Nanchang City,Nanchang City should take carbon emission reduction measures,including conceding the land to forestry,returning the land to water,limiting excessive expansion of construction land,optimizing distribution of urban land use,flexibly regulating land supply policies,and establishing carbon trading legal system,to reach the objective of combining land use plan with ecological construction.

  14. Derived crop management data for the LandCarbon Project

    Science.gov (United States)

    Schmidt, Gail; Liu, Shu-Guang; Oeding, Jennifer

    2011-01-01

    The LandCarbon project is assessing potential carbon pools and greenhouse gas fluxes under various scenarios and land management regimes to provide information to support the formulation of policies governing climate change mitigation, adaptation and land management strategies. The project is unique in that spatially explicit maps of annual land cover and land-use change are created at the 250-meter pixel resolution. The project uses vast amounts of data as input to the models, including satellite, climate, land cover, soil, and land management data. Management data have been obtained from the U.S. Department of Agriculture (USDA) National Agricultural Statistics Service (NASS) and USDA Economic Research Service (ERS) that provides information regarding crop type, crop harvesting, manure, fertilizer, tillage, and cover crop (U.S. Department of Agriculture, 2011a, b, c). The LandCarbon team queried the USDA databases to pull historic crop-related management data relative to the needs of the project. The data obtained was in table form with the County or State Federal Information Processing Standard (FIPS) and the year as the primary and secondary keys. Future projections were generated for the A1B, A2, B1, and B2 Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES) scenarios using the historic data values along with coefficients generated by the project. The PBL Netherlands Environmental Assessment Agency (PBL) Integrated Model to Assess the Global Environment (IMAGE) modeling framework (Integrated Model to Assess the Global Environment, 2006) was used to develop coefficients for each IPCC SRES scenario, which were applied to the historic management data to produce future land management practice projections. The LandCarbon project developed algorithms for deriving gridded data, using these tabular management data products as input. The derived gridded crop type, crop harvesting, manure, fertilizer, tillage, and cover crop

  15. CARBON SEQUESTRATION ON SURFACE MINE LANDS

    Energy Technology Data Exchange (ETDEWEB)

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2004-08-02

    The April-June 2004 quarter was dedicated to the establishment of monitoring systems for all the new research areas. Hydrology and water quality monitoring continues to be conducted on all areas as does weather data pertinent to the research. Studies assessing specific questions pertaining to carbon flux has been established and the invasion of the vegetation by small mammals is being quantified. The approval of two experimental practices associated with this research by the United States Office of Surface Mining was a major accomplishment during this period of time. These experimental practices will eventually allow for tree planting on long steep slopes with loose grading systems and for the use of loose dumped spoil on mountain top removal areas with no grading in the final layer of rooting material for tree establishment.

  16. CARBON SEQUESTRATION ON SURFACE MINE LANDS

    Energy Technology Data Exchange (ETDEWEB)

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2003-10-30

    The 2002-2003 Department of Energy plantings amounted to 164 acres containing 111,520 tree seedlings in eastern and western Kentucky. Data gathered on these trees included an inventory to determine survival of all planted species. A sub-sample of seedlings was selected to assess the height and diameter of individual species of seedlings established. Additional efforts involved collection of soil sample and litter samples, analysis of herbaceous ground cover from vegetation clip plots and leaf area on each tree species, and development of tissue collections. All areas were sampled for penetration resistance, penetration depth (or depth to refusal), and bulk density at various depths. Rain fall events and flow rates were recorded. The water quality of runoff samples involved the determination of total and settleable solids and particle size distribution. A study was initiated that will focus on the colonization of small mammals from forest edges to various areas located on reclaimed surface mines. This effort will provide a better understanding of the role small mammals and birds have in the establishment of plant communities on mine lands that will be useful in developing and improving reclamation techniques.

  17. Integrating livestock manure with a corn-soybean bioenergy cropping system improves short-term carbon sequestration rates and net global warming potential

    Energy Technology Data Exchange (ETDEWEB)

    Thelen, K.D.; Fronning, B.E.; Kravchenko, A.; Min, D.H.; Robertson, G.P. [Michigan State University, East Lansing, MI 48824 (United States)

    2010-07-15

    Carbon cycling and the global warming potential (GWP) of bioenergy cropping systems with complete biomass removal are of agronomic and environmental concern. Corn growers who plan to remove corn stover as a feedstock for the emerging cellulosic ethanol industry will benefit from carbon amendments such as manure and compost, to replace carbon removed with the corn stover. The objective of this research was to determine the effect of beef cattle feedlot manure and composted dairy manure on short-term carbon sequestration rates and net global warming potential (GWP) in a corn-soybean rotation with complete corn-stover removal. Field experiments consisting of a corn-soybean rotation with whole-plant corn harvest, were conducted near East Lansing, MI over a three-year period beginning in 2002. Compost and manure amendments raised soil carbon (C) at a level sufficient to overcome the C debt associated with manure production, manure collection and storage, land application, and post-application field emissions. The net GWP in carbon dioxide equivalents for the manure and compost amended cropping systems was -934 and -784 g m{sup -2} y{sup -1}, respectively, compared to 52 g m{sup -2} y{sup -1} for the non-manure amended synthetic fertilizer check. This work further substantiates the environmental benefits associated with renewable fuels and demonstrates that with proper management, the integration of livestock manures in biofuel cropping systems can enhance greenhouse gas (GHG) remediation. (author)

  18. Assessing the implications of human land-use change for the transient climate response to cumulative carbon emissions

    Science.gov (United States)

    Simmons, C. T.; Matthews, H. D.

    2016-03-01

    Recent research has shown evidence of a linear climate response to cumulative CO2 emissions, which implies that the source, timing, and amount of emissions does not significantly influence the climate response per unit emission. Furthermore, these analyses have generally assumed that the climate response to land-use CO2 emissions is equivalent to that of fossil fuels under the assumption that, once in the atmosphere, the radiative forcing induced by CO2 is not sensitive to the emissions source. However, land-cover change also affects surface albedo and the strength of terrestrial carbon sinks, both of which have an additional climate effect. In this study, we use a coupled climate-carbon cycle model to assess the climate response to historical and future cumulative land-use CO2 emissions, in order to compare it to the response to fossil fuel CO2. We find that when we isolate the CO2-induced (biogeochemical) temperature changes associated with land-use change, then the climate response to cumulative land-use emissions is equivalent to that of fossil fuel CO2. We show further that the globally-averaged albedo-induced biophysical cooling from land-use change is non-negligible and may be of comparable magnitude to the biogeochemical warming, with the result that the net climate response to land-use change is substantially different from a linear response to cumulative emissions. However, our new simulations suggest that the biophysical cooling from land-use change follows its own independent (negative) linear response to cumulative net land-use CO2 emissions, which may provide a useful scaling factor for certain applications when evaluating the full transient climate response to emissions.

  19. CARBON SEQUESTRATION ON SURFACE MINE LANDS

    Energy Technology Data Exchange (ETDEWEB)

    Donald H. Graves; Christopher Barton; Richard Sweigard; Richard Warner

    2005-02-25

    The October-December Quarter was dedicated to analyzing the first two years tree planting activities and evaluation of the results. This included the analyses of the species success at each of the sites and quantifying the data for future year determination of research levels. Additional detailed studies have been planned to further quantify total carbon storage accumulation on the research areas. At least 124 acres of new plantings will be established in 2005 to bring the total to 500 acres or more in the study area across the state of Kentucky. During the first 2 years of activities, 172,000 tree seedlings were planted on 257 acres in eastern Kentucky and 77,520 seedlings were planted on 119 acres in western Kentucky. The quantities of each species was discussed in the first Annual Report. A monitoring program was implemented to measure treatment effects on above and below ground C and nitrogen (N) pools and fluxes. A sampling strategy was devised that will allow for statistical comparisons of the various species within planting conditions and sites. Seedling heights and diameters are measured for initial status and re-measured on an annual basis. Leaves were harvested and leaf area measurements were performed. They were then dried and weighed and analyzed for C and N. Whole trees were removed to determine biomass levels and to evaluate C and N levels in all components of the trees. Clip plots were taken to determine herbaceous production and litter was collected in baskets and gathered each month to quantify C & N levels. Soil samples were collected to determine the chemical and mineralogical characterization of each area. The physical attributes of the soils are also being determined to provide information on the relative level of compaction. Hydrology and water quality monitoring is being conducted on all areas. Weather data is also being recorded that measures precipitation values, temperature, relative humidity wind speed and direction and solar radiation

  20. Seasonal distribution of dissolved inorganic carbon and net community production on the Bering Sea shelf

    Directory of Open Access Journals (Sweden)

    J. T. Mathis

    2010-01-01

    Full Text Available The southeastern shelf of the Bering Sea is one of the ocean's most productive ecosystems and sustains more than half of the total US fish landings annually. However, the character of the Bering Sea shelf ecosystem has undergone a dramatic shift over the last several decades, causing notable increases in the dominance of temperate features coupled to the decline of arctic species and decreases in the abundance of commercially important organisms. In order to assess the current state of primary production in the southeastern Bering Sea, we measured the spatio-temporal distribution and controls on dissolved inorganic carbon (DIC concentrations in spring and summer of 2008 across six shelf domains defined by differing biogeochemical characteristics. DIC concentrations were tightly coupled to salinity in spring and ranged from ~1900 μmol kg−1 over the inner shelf to ~2400 μmol kg−1 in the deeper waters of the Bering Sea. In summer, DIC concentrations were lower due to dilution from sea ice melt and primary production. Concentrations were found to be as low ~1800 μmol kg−1 over the inner shelf. We found that DIC concentrations were drawn down 30–150 μmol kg−1 in the upper 30 m of the water column due to primary production between the spring and summer occupations. Using the seasonal drawdown of DIC, estimated rates of net community production (NCP on the inner, middle, and outer shelf averaged 28±10 mmol C m−2 d−1. However, higher rates of NCP (40–47 mmol C m−2 d−1 were observed in the ''Green Belt'' where the greatest confluence of nutrient-rich basin water and iron-rich shelf water occurs. We estimated that in 2008, total productivity across the shelf was on the order of ~105 Tg C yr−1. Due to the paucity of consistent, comparable productivity data, it is impossible at this time to quantify whether the system is becoming

  1. A Preliminary Study of the Carbon Emissions Reduction Effects of Land Use Control

    Science.gov (United States)

    Chuai, Xiaowei; Huang, Xianjin; Qi, Xinxian; Li, Jiasheng; Zuo, Tianhui; Lu, Qinli; Li, Jianbao; Wu, Changyan; Zhao, Rongqin

    2016-11-01

    Land use change not only directly influences carbon storage in terrestrial ecosystems but can also cause energy-related carbon emissions. This study examined spatiotemporal land use change across Jiangsu Province, China; calculated vegetation carbon storage loss caused by land use change and energy-related carbon emissions; analysed the relationship among land use change, carbon emissions and social-economic development; and optimized land use structure to maximize carbon storage. Our study found that 13.61% of the province’s land area underwent a change in type of land use between 1995 and 2010, mainly presented as built-up land expansion and cropland shrinkage, especially in southern Jiangsu. Land use change caused a 353.99 × 104 t loss of vegetation carbon storage loss. Energy-related carbon emissions increased 2.5 times from 1995 to 2013; the energy consumption structure has been improved to some extent while still relying on coal. The selected social-economic driving forces have strong relationships with carbon emissions and land use changes, while there are also other determinants driving land use change, such as land use policy. The optimized land use structure will slow the rate of decline in vegetation carbon storage compared with the period between 1995 and 2010 and will also reduce energy-related carbon emissions by 12%.

  2. Land use effects on terrestrial carbon sources and sinks

    Institute of Scientific and Technical Information of China (English)

    Josep; G.; Canadell

    2002-01-01

    Current and past land use practices are critical in determining the distribution and size of global terrestrial carbon (C) sources and sinks. Althoughfossil fuel emissions dominate the anthropogenic perturbation of the global C cycle, land use still drives the largest portion of anthropogenic emissions in a number of tropical regions of Asia. The size of the emission flux owing to land use change is still the biggest uncertainty in the global C budget. The Intergovernmental Panel on Climate Change (IPCC) reported a flux term of 1.7 PgC@a-1 for 1990-1995 but more recent estimates suggest the magnitude of this source may be only of 0.96 PgC@a-1 for the 1990s. In addition, current and past land use practices are now thought to contribute to a large degree to the northern hemisphere terrestrial sink, and are the dominant driver for some regional sinks. However, mechanisms other than land use change need to be invoked in order to explain the inferred C sink in the tropics. Potential candidates are the carbon dioxide (CO2) fertilization and climate change; fertilization due to nitrogen (N) deposition is believed to be small or nil. Although the potential for managing C sinks is limited, improved land use management and new land uses such as reforestation and biomass fuel cropping, can further enhance current terrestrial C sinks. Best management practices in agriculture alone could sequester 0.4-0.8 PgC per year in soils if implemented globally. New methodologies to ensure verification and permanency of C sequestration need to be developed.

  3. LandCarbon Conterminous United States Land-Use/Land-Cover Mosaics 1992-2050

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Source data for this variable were obtained from the USGS Land Cover Trends Project. Annual maps of LULC were extrapolated for baseline years (1992 to 2005) and...

  4. Land use and land management effects on soil organic carbon stock in Mediterranean agricultural areas (Southern Spain)

    Science.gov (United States)

    Parras-Alcántara, Luis; Lozano-García, Beatriz

    2014-05-01

    INTRODUCTION Soils play a key role in the carbon geochemical cycle. Agriculture contributes to carbon sequestration through photosynthesis and the incorporation of carbon into carbohydrates. Soil management is one of the best tools for climate change mitigation. Small increases or decreases in soil carbon content due to changes in land use or management practices, may result in a significant net exchange of carbon between the soil carbon pool and the atmosphere. In the last decades arable crops (AC) have been transformed into olive grove cultivations (OG) or vineyards (V) in Mediterranean areas. A field study was conducted to determine long-term effects of land use change (LUC) (AC by OG and V) on soil organic carbon (SOC), total nitrogen (TN), C:N ratio and their stratification in Calcic-Chromic Luvisols (LVcc/cr) in Mediterranean conditions. MATERIAL AND METHODS An unirrigated farm in Montilla-Moriles (Córdoba, Spain) cultivated under conventional tillage (animal power with lightweight reversible plows and non-mineral fertilization or pesticides) was selected for study in 1965. In 1966, the farm was divided into three plots with three different uses (AC, OG and V). The preliminary analyses were realized in 1965 for AC (AC1), and the second analyses were realized in 2011 for AC (AC2 - winter crop rotation with annual wheat and barley, receiving mineral fertilization or pesticides), OG (annual passes with disk harrow and cultivator in the spring, followed by a tine harrow in the summer receiving mineral fertilization and weed control with residual herbicides), and V (with three or five chisel passes a year from early spring to early autumn with mineral fertilization or pesticides.). In all cases (AC1, AC2, OG and V) were collected soil entire profiles. Soil properties determined were: soil particle size, bulk density, SOC, TN, C:N ratio, stocks and SRs. The statistical significance of the differences in the variables between land use practices was tested using the

  5. Impacts of land-use and climate changes on ecosystem productivity and carbon cycle in the cropping-grazing transitional zone in China

    Institute of Scientific and Technical Information of China (English)

    GAO Zhiqiang; LIU Jiyuan; CAO Mingkui; LI Kerang; TAO Bo

    2005-01-01

    The impact of land-use/land-cover and climate changes on ecosystem productivity and carbon cycle is one of the most important issues in global change studies. In the past 20 years, the climate and land-use in China have changed significantly and have had important ecological consequences, especially in ecologically sensitive regions, e.g. the cropping-grazing transition zone (CGTZ). Here we present a study that used a process-based ecosystem model and data of land-use changes based on remote sensing and of climate change at high spatial and temporal resolution to estimate the impacts of land-use and climate changes on net primary productivity (NPP), vegetation carbon storage, soil heterotrophic respiration (HR), carbon storage and net ecosystem productivity (NEP) in the CGTZ of China. The results show that the warming and decreases in precipitation in CGTZ reduced NPP by 3.4%, increased HR by 4.3%, and reduced annual mean total NEP by 33.7Tg from the 1980s to the 1990s. Although carbon storage in vegetation and soil was increasing because the mean NPP for the period was higher than HR, the decreasing NEP indicate that climate change reduced the carbon uptake rate. However, land-use changes in this zone caused increases in NPP by 3.8%, vegetation carbon storage by 2.4%, and annual total NEP by 0.59Tg. The land-use changes enhanced ecosystem carbon uptake, but not enough to offset the negative effect of the climate change. The climate change had greater impacts than the land-use change for the whole CGTZ zone, but had smaller impacts than the land-use change in the regions where it occurred.

  6. Inventory-based model estimates of the net impact of natural disturbances on the C balance of Canada’s managed forest lands

    Science.gov (United States)

    Stinson, G.; Kurz, W.; Neilson, E.; Metsaranta, J.

    2009-12-01

    The net impact of natural disturbances on the C budget of Canada’s managed forest lands (230 million ha) has not previously been estimated. Natural disturbances affect forest ecosystem C budgets by directly releasing C to the atmosphere, by transferring large quantities of living biomass to dead organic matter pools which subsequently decompose, and by altering the carbon uptake capacity of the affected ecosystems. We define the net impact as the difference in the forest carbon balance with and without a specific natural disturbance type. We estimated the net impact of fire and insect disturbances on Canada’s managed forest C budget from 1990 through 2007 using the CBM-CFS3, an inventory-based simulation model that uses data from Canada’s National Forest Carbon Monitoring, Accounting and Reporting System (NFCMARS). Four scenarios were simulated: (i) a base scenario that includes all natural disturbances, (ii) base with fire removed, (iii) base with insects removed, and (iv) base with both fire and insects removed. Disturbance impacts were found to be highly variable between years and not normally distributed about their means. Direct fire emissions ranged from 3 to 75 Tg C yr-1 (11 to 291 Mt CO2e yr-1, accounting for CO2, CO, CH4 and N2O) during 1990-2007. Fires that occurred during 1990-2007 reduced NEP during this same period by 1 to 5 Tg C yr-1 and insects reduced NEP by 1 to 17 Tg C yr-1. Fires resulted in a 1 to 12 Tg C yr-1 reduction in NPP while insects reduced NPP by 1 to 13 Tg C yr-1. Insect impacts on heterotrophic respiration (Rh) during 1990-2007 were minor because most of the recorded insect-induced tree mortality occurred towards the end of the period. Interactive effects between natural disturbances and forest management activities (harvest and salvage) were also analyzed. Quantification of natural disturbance impacts on the forest ecosystem C budget is not staight forward on a land base where natural and anthropogenic factors are interacting

  7. The seasonal carbon and water balances of the Cerrado environment of Brazil: Past, present, and future influences of land cover and land use

    Science.gov (United States)

    Arantes, Arielle Elias; Ferreira, Laerte G.; Coe, Michael T.

    2016-07-01

    The Brazilian savanna (known as Cerrado) is an upland biome made up of various vegetation types from herbaceous to arboreal. In this paper, MODIS remote sensing vegetation greenness from the Enhanced Vegetation Index (EVI) and evapotranspiration (ET) data for the 2000-2012 period were analyzed to understand the differences in the net primary productivity (NPP-proxy), carbon, and the evaporative flux of the major Cerrado natural and anthropic landscapes. The understanding of the carbon and evaporative fluxes of the main natural and anthropic vegetation types is of fundamental importance in studies regarding the impacts of land cover and land use changes in the regional and global climate. The seasonal dynamics of EVI and ET of the main natural and anthropic vegetation types of the Cerrado biome were analyzed using a total of 35 satellite-based samples distributed over representative Cerrado landscapes. Carbon and water fluxes were estimated for different scenarios, such as, a hypothetical unconverted Cerrado, 2002 and 2050 scenarios based on values derived from literature and on the PROBIO land cover and land use map for the Cerrado. The total growing season biomass for 2002 in the Cerrado region was estimated to be 28 gigatons of carbon and the evapotranspiration was 1336 gigatons of water. The mean estimated growing season evapotranspiration and biomass for 2002 was 576 Gt of water and 12 Gt of carbon for pasture and croplands compared to 760 Gt of water and 15 Gt of carbon for the Cerrado natural vegetation. In a modeled future scenario for the year 2050, the ET flux from natural Cerrado vegetation was 394 Gt less than in 2002 and 991 Gt less than in an unconverted scenario, with only natural vegetation, while the carbon was 8 Gt less than in 2002 and 21 Gt less than in this hypothetical pre-conversion Cerrado. On the other hand, the sum of the pasture and cropland ET flux increased by 405 Gt in 2050 relative to 2002 and the carbon by 11 Gt of carbon. Given the

  8. Net Community Metabolism and Seawater Carbonate Chemistry Scale Non-intuitively with Coral Cover

    Directory of Open Access Journals (Sweden)

    Heather N. Page

    2017-05-01

    Full Text Available Coral cover and reef health have been declining globally as reefs face local and global stressors including higher temperature and ocean acidification (OA. Ocean warming and acidification will alter rates of benthic reef metabolism (i.e., primary production, respiration, calcification, and CaCO3 dissolution, but our understanding of community and ecosystem level responses is limited in terms of functional, spatial, and temporal scales. Furthermore, dramatic changes in coral cover and benthic metabolism could alter seawater carbonate chemistry on coral reefs, locally alleviating or exacerbating OA. This study examines how benthic metabolic rates scale with changing coral cover (0–100%, and the subsequent influence of these coral communities on seawater carbonate chemistry based on mesocosm experiments in Bermuda and Hawaii. In Bermuda, no significant differences in benthic metabolism or seawater carbonate chemistry were observed for low (40% and high (80% coral cover due to large variability within treatments. In contrast, significant differences were detected between treatments in Hawaii with benthic metabolic rates increasing with increasing coral cover. Observed increases in daily net community calcification and nighttime net respiration scaled proportionally with coral cover. This was not true for daytime net community organic carbon production rates, which increased the most between 0 and 20% coral cover and then less so between 20 and 100%. Consequently, diel variability in seawater carbonate chemistry increased with increasing coral cover, but absolute values of pH, Ωa, and pCO2 were not significantly different during daytime. To place the results of the mesocosm experiments into a broader context, in situ seawater carbon dioxide (CO2 at three reef sites in Bermuda and Hawaii were also evaluated; reefs with higher coral cover experienced a greater range of diel CO2 levels, complementing the mesocosm results. The results from this study

  9. A new stepwise carbon cycle data assimilation system using multiple data streams to constrain the simulated land surface carbon cycle

    Science.gov (United States)

    Peylin, Philippe; Bacour, Cédric; MacBean, Natasha; Leonard, Sébastien; Rayner, Peter; Kuppel, Sylvain; Koffi, Ernest; Kane, Abdou; Maignan, Fabienne; Chevallier, Frédéric; Ciais, Philippe; Prunet, Pascal

    2016-09-01

    Large uncertainties in land surface models (LSMs) simulations still arise from inaccurate forcing, poor description of land surface heterogeneity (soil and vegetation properties), incorrect model parameter values and incomplete representation of biogeochemical processes. The recent increase in the number and type of carbon cycle-related observations, including both in situ and remote sensing measurements, has opened a new road to optimize model parameters via robust statistical model-data integration techniques, in order to reduce the uncertainties of simulated carbon fluxes and stocks. In this study we present a carbon cycle data assimilation system that assimilates three major data streams, namely the Moderate Resolution Imaging Spectroradiometer (MODIS)-Normalized Difference Vegetation Index (NDVI) observations of vegetation activity, net ecosystem exchange (NEE) and latent heat (LE) flux measurements at more than 70 sites (FLUXNET), as well as atmospheric CO2 concentrations at 53 surface stations, in order to optimize the main parameters (around 180 parameters in total) of the Organizing Carbon and Hydrology in Dynamics Ecosystems (ORCHIDEE) LSM (version 1.9.5 used for the Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations). The system relies on a stepwise approach that assimilates each data stream in turn, propagating the information gained on the parameters from one step to the next. Overall, the ORCHIDEE model is able to achieve a consistent fit to all three data streams, which suggests that current LSMs have reached the level of development to assimilate these observations. The assimilation of MODIS-NDVI (step 1) reduced the growing season length in ORCHIDEE for temperate and boreal ecosystems, thus decreasing the global mean annual gross primary production (GPP). Using FLUXNET data (step 2) led to large improvements in the seasonal cycle of the NEE and LE fluxes for all ecosystems (i.e., increased amplitude for temperate ecosystems). The

  10. [Net CO2 exchange and carbon isotope flux in Acacia mangium plantation].

    Science.gov (United States)

    Zou, Lu-Liu; Sun, Gu-Chou; Zhao, Ping; Cai, Xi-An; Zeng, Xiao-Ping; Wang, Quan

    2009-11-01

    By using stable carbon isotope technique, the leaf-level 13C discrimination was integrated to canopy-scale photosynthetic discrimination (Deltacanopy) through weighted the net CO2 assimilation (Anet) of sunlit and shaded leaves and the stand leaf area index (L) in an A. mangium plantation, and the carbon isotope fluxes from photosynthesis and respiration as well as their net exchange flux were obtained. There was an obvious diurnal variation in Deltacanopy, being lower at dawn and at noon time (18.47 per thousand and 19.87 per thousand, respectively) and the highest (21.21 per thousand) at dusk. From the end of November to next May, the Deltacanopy had an increasing trend, with an annual average of (20.37 +/- 0.29) per thousand. The carbon isotope ratios of CO2 from autotrophic respiration (excluding daytime foliar respiration) and heterotrophic respiration were respectively (- 28.70 +/- 0.75) per thousand and (- 26.75 +/- 1.3) per thousand in average. The delta13 C of nighttime ecosystem-respired CO2 in May was the lowest (-30.14 per thousand), while that in November was the highest (-28.01 per thousand). The carbon isotope flux of CO2 between A. mangium forest and atmosphere showed a midday peak of 178.5 and 217 micromol x m(-2) x s(-1) x per thousand in May and July, with the daily average of 638.4 and 873.2 micromol x m(-2) x s(-1) x per thousand, respectively. The carbon isotope flux of CO2 absorbed by canopy leaves was 1.6-2.5 times higher than that of CO2 emitted from respiration, suggesting that a large sum of CO2 was absorbed by A. mangium, which decreased the atmospheric CO2 concentration and improved the environment.

  11. Interactions between nitrogen deposition, land cover conversion, and climate change determine the contemporary carbon balance of Europe

    Directory of Open Access Journals (Sweden)

    G. Churkina

    2010-09-01

    Full Text Available European ecosystems are thought to take up large amounts of carbon, but neither the rate nor the contributions of the underlying processes are well known. In the second half of the 20th century, carbon dioxide concentrations have risen by more that 100 ppm, atmospheric nitrogen deposition has more than doubled, and European mean temperatures were increasing by 0.02 °C yr−1. The extents of forest and grasslands have increased with the respective rates of 5800 km2 yr−1 and 1100 km2 yr−1 as agricultural land has been abandoned at a rate of 7000 km2 yr−1. In this study, we analyze the responses of European land ecosystems to the aforementioned environmental changes using results from four process-based ecosystem models: BIOME-BGC, JULES, ORCHIDEE, and O-CN. The models suggest that European ecosystems sequester carbon at a rate of 56 TgC yr−1 (mean of four models for 1951–2000 with strong interannual variability (±88 TgC yr−1, average across models and substantial inter-model uncertainty (±39 TgC yr−1. Decadal budgets suggest that there has been a continuous increase in the mean net carbon storage of ecosystems from 85 TgC yr−1 in 1980s to 108 TgC yr−1 in 1990s, and to 114 TgC yr−1 in 2000–2007. The physiological effect of rising CO2 in combination with nitrogen deposition and forest re-growth have been identified as the important explanatory factors for this net carbon storage. Changes in the growth of woody vegetation are suggested as an important contributor to the European carbon sink. Simulated ecosystem responses were more consistent for the two models accounting for terrestrial carbon-nitrogen dynamics than for the two models which only accounted for carbon cycling and the effects of land cover change. Studies of the interactions of carbon-nitrogen dynamics with

  12. Impacts of land cover and climate data selection on understanding terrestrial carbon dynamics and the CO2 airborne fraction

    Directory of Open Access Journals (Sweden)

    E. L. Hodson

    2011-08-01

    Full Text Available Terrestrial and oceanic carbon cycle processes remove ~55 % of global carbon emissions, with the remaining 45 %, known as the "airborne fraction", accumulating in the atmosphere. The long-term dynamics of the component fluxes contributing to the airborne fraction are challenging to interpret, but important for informing fossil-fuel emission targets and for monitoring the trends of biospheric carbon fluxes. Climate and land-cover forcing data for terrestrial ecosystem models are a largely unexplored source of uncertainty in terms of their contribution to understanding airborne fraction dynamics. Here we present results using a single dynamic global vegetation model forced by an ensemble experiment of climate (CRU, ERA-Interim, NCEP-DOE II, and diagnostic land-cover datasets (GLC2000, GlobCover, MODIS. For the averaging period 1996–2005, forcing uncertainties resulted in a large range of simulated global carbon fluxes, up to 13 % for net primary production (52.4 to 60.2 Pg C a−1 and 19 % for soil respiration (44.2 to 54.8 Pg C a−1. The sensitivity of contemporary global terrestrial carbon fluxes to climate strongly depends on forcing data (1.2–5.9 Pg C K−1 or 0.5 to 2.7 ppmv CO2 K−1, but weakening carbon sinks in sub-tropical regions and strengthening carbon sinks in northern latitudes are found to be robust. The climate and land-cover combination that best correlate to the inferred carbon sink, and with the lowest residuals, is from observational data (CRU rather than reanalysis climate data and with land-cover categories that have more stringent criteria for forest cover (MODIS. Since 1998, an increasing positive trend in residual error from bottom-up accounting of global sinks and sources (from 0.03 (1989–2005 to 0.23 Pg C a−1 (1998–2005 suggests that either modeled drought sensitivity of carbon fluxes is too high, or that carbon emissions from net land-cover change is too large.

  13. Management effects on net ecosystem carbon and GHG budgets at European crop sites

    DEFF Research Database (Denmark)

    Ceschia, Eric; Bêziat, P; Dejoux, J.F.

    2010-01-01

    . The variability of the different terms and their relative contributions to the net ecosystem carbon budget (NECB) were analysed for all site-years, and the effect of management on NECB was assessed. To account for greenhouse gas (GHG) fluxes that were not directly measured on site, we estimated the emissions......, and more studies are needed to assess the effects of management on crop efficiency.......The greenhouse gas budgets of 15 European crop sites covering a large climatic gradient and corresponding to 41 site-years were estimated. The sites included a wide range of management practices (organic and/or mineral fertilisation, tillage or ploughing, with or without straw removal...

  14. Implications of land-use change on forest carbon stocks in the eastern United States

    Science.gov (United States)

    Puhlick, Joshua; Woodall, Christopher; Weiskittel, Aaron

    2017-02-01

    Given the substantial role that forests play in removing CO2 from the atmosphere, there has been a growing need to evaluate the carbon (C) implications of various forest management and land-use decisions. Although assessment of land-use change is central to national-level greenhouse gas monitoring guidelines, it is rarely incorporated into forest stand-level evaluations of C dynamics and trajectories. To better inform the assessment of forest stand C dynamics in the context of potential land-use change, we used a region-wide repeated forest inventory (n = 71 444 plots) across the eastern United States to assess forest land-use conversion and associated changes in forest C stocks. Specifically, the probability of forest area reduction between 2002–2006 and 2007–2012 on these plots was related to key driving factors such as proportion of the landscape in forest land use, distance to roads, and initial forest C. Additional factors influencing the actual reduction in forest area were then used to assess the risk of forest land-use conversion to agriculture, settlement, and water. Plots in forests along the Great Plains had the highest periodic (approximately 5 years) probability of land-use change (0.160 ± 0.075; mean ± SD) with forest conversion to agricultural uses accounting for 70.5% of the observed land-use change. Aboveground forest C stock change for plots with a reduction in forest area was ‑4.2 ± 17.7 Mg ha‑1 (mean ± SD). The finding that poorly stocked stands and/or those with small diameter trees had the highest probability of conversion to non-forest land uses suggests that forest management strategies can maintain the US terrestrial C sink not only in terms of increased net forest growth but also retention of forest area to avoid conversion. This study highlights the importance of considering land-use change in planning and policy decisions that seek to maintain or enhance regional C sinks.

  15. Simulating the impacts of land use in northwest Europe on Net Ecosystem Exchange (NEE): the role of arable ecosystems, grasslands and forest plantations in climate change mitigation.

    Science.gov (United States)

    Abdalla, Mohamed; Saunders, Matthew; Hastings, Astley; Williams, Mike; Smith, Pete; Osborne, Bruce; Lanigan, Gary; Jones, Mike B

    2013-11-01

    In this study, we compared measured and simulated Net Ecosystem Exchange (NEE) values from three wide spread ecosystems in the southeast of Ireland (forest, arable and grassland), and investigated the suitability of the DNDC (the DeNitrification-DeComposition) model to estimate present and future NEE. Although, the field-DNDC version overestimated NEE at temperatures >5 °C, forest-DNDC under-estimated NEE at temperatures >5 °C. The results suggest that the field/forest DNDC models can successfully estimate changes in seasonal and annual NEE from these ecosystems. Differences in NEE were found to be primarily land cover specific. The annual NEE was similar for the grassland and arable sites, but due to the contribution of exported carbon, the soil carbon increased at the grassland site and decreased at the arable site. The NEE of the forest site was an order of magnitude larger than that of the grassland or arable ecosystems, with large amounts of carbon stored in woody biomass and the soil. The average annual NEE, GPP and Reco values over the measurement period were -904, 2379 and 1475 g C m(-2) (forest plantations), -189, 906 and 715 g C m(-2) (arable systems) and -212, 1653 and 1444 g C m(-2) (grasslands), respectively. The average RMSE values were 3.8 g C m(-2) (forest plantations), 0.12 g C m(-2) (arable systems) and 0.21 g C m(-2) (grasslands). When these models were run with climate change scenarios to 2060, predictions show that all three ecosystems will continue to operate as carbon sinks. Further, climate change may decrease the carbon sink strength in the forest plantations by up to 50%. This study supports the use of the DNDC model as a valid tool to predict the consequences of climate change on NEE from different ecosystems. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Hysteretic Behavior of Tubular Steel Braces Having Carbon Fiber Reinforced Polymer Reinforcement Around End Net Sections

    Directory of Open Access Journals (Sweden)

    Cem Haydaroğlu

    2015-12-01

    Full Text Available This study presents an experimental investigation into the seismic retrofit of tubular steel braces using carbon fiber reinforced polymer (CFRP members. CFRP retrofitting of net sections for compact tubes are proposed for delaying potential local net section failure. A total of almost full-scale three (TB-1, TB-2, and TB-3 compact steel tubular specimens were designed per AISC specifications, constructed, and cyclically tested to fracture. Retrofitted braces, when compared to the reference specimen, developed fuller hysteretic curves. Increase in cumulative hysteretic energy dissipation and the elongation in fracture life in the specimen retrofitted with CFRP plates and CFRP sheet wraps at net sections are observed during testing. This resulted in a maximum of 82.5% more dissipated energy for compact tube specimens. Also, this retrofit provided a longer experimental fracture life (maximum 59% more. Due to fracture initiation during the last cycles, significant reductions in strength and stiffness have been obtained. No significant change (maximum 10% in the brace stiffness was observed, which could be desirable in seismic retrofit applications. Pushover analysis per FEMA 356 for the bare specimen shows that FEMA does not represent actual brace behavior in the compression side although pushover and experimental results are in good agreement in the tension side.

  17. Assessment on the rates and potentials of soil organic carbon sequestration in agricultural lands in Japan using a process-based model and spatially explicit land-use change inventories - Part 2: Future potentials

    Science.gov (United States)

    Yagasaki, Y.; Shirato, Y.

    2014-08-01

    Future potentials of the sequestration of soil organic carbon (SOC) in agricultural lands in Japan were estimated using a simulation system we recently developed to simulate SOC stock change at country-scale under varying land-use change, climate, soil, and agricultural practices, in a spatially explicit manner. Simulation was run from 1970 to 2006 with historical inventories, and subsequently to 2020 with future scenarios of agricultural activity comprised of various agricultural policy targets advocated by the Japanese government. Furthermore, the simulation was run subsequently until 2100 while forcing no temporal changes in land-use and agricultural activity to investigate duration and course of SOC stock change at country scale. A scenario with an increased rate of organic carbon input to agricultural fields by intensified crop rotation in combination with the suppression of conversion of agricultural lands to other land-use types was found to have a greater reduction of CO2 emission by enhanced soil carbon sequestration, but only under a circumstance in which the converted agricultural lands will become settlements that were considered to have a relatively lower rate of organic carbon input. The size of relative reduction of CO2 emission in this scenario was comparable to that in another contrasting scenario (business-as-usual scenario of agricultural activity) in which a relatively lower rate of organic matter input to agricultural fields was assumed in combination with an increased rate of conversion of the agricultural fields to unmanaged grasslands through abandonment. Our simulation experiment clearly demonstrated that net-net-based accounting on SOC stock change, defined as the differences between the emissions and removals during the commitment period and the emissions and removals during a previous period (base year or base period of Kyoto Protocol), can be largely influenced by variations in future climate. Whereas baseline-based accounting, defined

  18. Impacts of land cover and climate data selection on understanding terrestrial carbon dynamics and the CO2 airborne fraction

    Directory of Open Access Journals (Sweden)

    N. E. Zimmermann

    2011-02-01

    Full Text Available Terrestrial and oceanic carbon cycle processes remove ~ 55% of global carbon emissions, with the remaining 45%, known as the "airborne fraction", accumulating in the atmosphere. The long-term dynamics of the component fluxes contributing to the airborne fraction are challenging to interpret, but important for informing fossil-fuel emission targets and for monitoring the trends of biospheric carbon fluxes. Climate and land-cover forcing data for terrestrial ecosystem models are a largely unexplored source of uncertainty in terms of their contribution to understanding airborne fraction dynamics. Here we present results using a single dynamic global vegetation model forced by an ensemble experiment of climate (CRU, ERA-Interim, NCEP-DOE II, and diagnostic land-cover datasets (GLC2000, GlobCover, MODIS. Forcing uncertainties resulted in a large range of simulated global carbon fluxes, up to 13% for net primary production (52.4 to 60.2 Pg C a−1 and 19% for soil respiration (44.2 to 54.8 Pg C a−1. The sensitivity of contemporary global terrestrial carbon fluxes to climate strongly depends on forcing data (1.2–5.9 Pg C K−1 or 0.5 to 2.7 ppmv CO2 K−1, but weakening carbon sinks in sub-tropical regions and strengthening carbon sinks in northern latitudes are found to be robust. The climate and land-cover combination that best correlate to the inferred carbon sink, and with the lowest residuals, is from observational data (CRU rather than reanalysis climate data and with land-cover categories that have more stringent criteria for forest cover (MODIS. Since 1998, an increasing positive trend in residual error from bottom-up accounting of global sinks and sources (from 0.03 (1989–2005 to 0.23 Pg C a−1 (1998–2005 suggests that either modeled drought sensitivity of carbon fluxes is too high, or that the trend toward decreased net land-use fluxes (~ 0.5 Pg C is overestimated.

  19. Net ecosystem carbon exchange in three contrasting Mediterranean ecosystems – the effect of drought

    Directory of Open Access Journals (Sweden)

    T. S. David

    2007-09-01

    Full Text Available Droughts reduce gross primary production (GPP and ecosystem respiration (Reco, contributing to most of the inter-annual variability in terrestrial carbon sequestration. In seasonally dry climates (Mediterranean, droughts result from reductions in annual rainfall and changes in rain seasonality. We compared carbon fluxes measured by the eddy covariance technique in three contrasting ecosystems in southern Portugal: an evergreen oak woodland (savannah-like with ca.~21% tree crown cover, a grassland dominated by herbaceous annuals and a coppiced short-rotation eucalyptus plantation. During the experimental period (2003–2006 the eucalyptus plantation was always the strongest sink for carbon: net ecosystem exchange rate (NEE between −861 and −399 g C m−2 year−1. The oak woodland and the grassland were much weaker sinks for carbon: NEE varied in the oak woodland between −140 and −28 g C m−2 year−1 and in the grassland between −190 and +49 g C m−2 year−1. The eucalyptus stand had higher GPP and a lower proportion of GPP spent in respiration than the other systems. The higher GPP resulted from high leaf area duration (LAD, as a surrogate for the photosynthetic photon flux density absorbed by the canopy. The eucalyptus had also higher rain use efficiency (GPP per unit of rain volume and light use efficiency (the daily GPP per unit incident photosynthetic photon flux density than the other two ecosystems. The effects of a severe drought could be evaluated during the hydrological-year (i.e., from October to September of 2004–2005. Between October 2004 and June 2005 the precipitation was only 40% of the long-term average. In 2004–2005 all ecosystems had GPP lower than in wetter years and carbon sequestration was strongly restricted (less negative NEE. The grassland was a net source of carbon dioxide (+49 g C m−2 year−1. In the oak woodland a large proportion of GPP resulted from carbon assimilated by its annual vegetation

  20. Divergent predictions of carbon storage between two global land models: attribution of the causes through traceability analysis

    Science.gov (United States)

    Rafique, Rashid; Xia, Jianyang; Hararuk, Oleksandra; Asrar, Ghassem R.; Leng, Guoyong; Wang, Yingping; Luo, Yiqi

    2016-07-01

    Representations of the terrestrial carbon cycle in land models are becoming increasingly complex. It is crucial to develop approaches for critical assessment of the complex model properties in order to understand key factors contributing to models' performance. In this study, we applied a traceability analysis which decomposes carbon cycle models into traceable components, for two global land models (CABLE and CLM-CASA') to diagnose the causes of their differences in simulating ecosystem carbon storage capacity. Driven with similar forcing data, CLM-CASA' predicted ˜ 31 % larger carbon storage capacity than CABLE. Since ecosystem carbon storage capacity is a product of net primary productivity (NPP) and ecosystem residence time (τE), the predicted difference in the storage capacity between the two models results from differences in either NPP or τE or both. Our analysis showed that CLM-CASA' simulated 37 % higher NPP than CABLE. On the other hand, τE, which was a function of the baseline carbon residence time (τ'E) and environmental effect on carbon residence time, was on average 11 years longer in CABLE than CLM-CASA'. This difference in τE was mainly caused by longer τ'E of woody biomass (23 vs. 14 years in CLM-CASA'), and higher proportion of NPP allocated to woody biomass (23 vs. 16 %). Differences in environmental effects on carbon residence times had smaller influences on differences in ecosystem carbon storage capacities compared to differences in NPP and τ'E. Overall, the traceability analysis showed that the major causes of different carbon storage estimations were found to be parameters setting related to carbon input and baseline carbon residence times between two models.

  1. Climatic Benefit of Swiss Forest Cover Change: Including Albedo Change into Net Carbon Balance

    Science.gov (United States)

    Schwaab, J.; Lehning, M.; Bebi, P.

    2012-12-01

    Forests influence climate through physical, chemical and biological processes. It has been shown that warming caused by the comparatively low albedo of forests (albedo-effect), can reduce or even exceed cooling caused by carbon storage in forests (CO2-effect). Although warming caused by albedo and the amount of carbon storage depend on local characteristics, studies are lacking that investigate the combined local patterns of albedo and CO2-effect. Our study area, Switzerland, provides a variety of geographical features and thus the possibility to show how different geographical variables influence the two effects. We used the concept of radiative forcing to compare the effect of a changing albedo and a change in atmospheric CO2 concentration due to land cover change in the past. The change of forest cover was analysed over a period of 12 years based on aerial photographs. We estimate the albedo-effect by combining albedo data derived from the satellite sensor MODIS and data on snow cover derived from the satellite sensor AVHRR. Changes in carbon storage were calculated as differences in biomass and soil stocks of specific land cover classes. We found carbon storage induced cooling to be higher than albedo induced warming everywhere in Switzerland. However, especially in altitudes over 1200 m the albedo-effect reduced the benefits of carbon storage by more than 50%. In lower altitudes the albedo change was less important. The albedo-effect in altitudes above 1200 m was more relevant because of a more persistent snow-cover, a slightly higher global radiation and less additional carbon storage. The relevance of warming caused by an albedo change did not only depend on altitude, but also on the characteristics of forest cover change. While transitions from open land to open forest were accompanied by high albedo changes, the albedo change was only marginal if open forest turned into closed forest. Since snow cover has a large influence on the albedo effect, we included

  2. Crater Morphology in the Phoenix Landing Ellipse: Insights Into Net Erosion and Ice Table Depth

    Science.gov (United States)

    Noe Dobrea, E. Z.; Stoker, C. R.; McKay, C. P.; Davila, A. F.; Krco, M.

    2015-01-01

    Icebreaker [1] is a Discovery class mission being developed for future flight opportunities. Under this mission concept, the Icebreaker payload is carried on a stationary lander, and lands in the same landing ellipse as Phoenix. Samples are acquired from the subsurface using a drilling system that penetrates into materials which may include loose or cemented soil, icy soil, pure ice, rocks, or mixtures of these. To avoid the complexity of mating additional strings, the drill is single-string, limiting it to a total length of 1 m.

  3. Will the tropical land biosphere dominate the climate-carbon cycle feedback during the twenty-first century?

    Energy Technology Data Exchange (ETDEWEB)

    Raddatz, T.J.; Reick, C.H. [Max Planck Institute for Biogeochemistry, Jena (Germany); Max Planck Institute for Meteorology, Hamburg (Germany); Knorr, W. [Max Planck Institute for Biogeochemistry, Jena (Germany); QUEST, University of Bristol, Bristol (United Kingdom); Kattge, J. [Max Planck Institute for Biogeochemistry, Jena (Germany); Roeckner, E.; Schnur, R.; Schnitzler, K.G.; Wetzel, P.; Jungclaus, J. [Max Planck Institute for Meteorology, Hamburg (Germany)

    2007-11-15

    Global warming caused by anthropogenic CO{sub 2} emissions is expected to reduce the capability of the ocean and the land biosphere to take up carbon. This will enlarge the fraction of the CO{sub 2} emissions remaining in the atmosphere, which in turn will reinforce future climate change. Recent model studies agree in the existence of such a positive climate-carbon cycle feedback, but the estimates of its amplitude differ by an order of magnitude, which considerably increases the uncertainty in future climate projections. Therefore we discuss, in how far a particular process or component of the carbon cycle can be identified, that potentially contributes most to the positive feedback. The discussion is based on simulations with a carbon cycle model, which is embedded in the atmosphere/ocean general circulation model ECHAM5/MPI-OM. Two simulations covering the period 1860-2100 are conducted to determine the impact of global warming on the carbon cycle. Forced by historical and future carbon dioxide emissions (following the scenario A2 of the Intergovernmental Panel on Climate Change), they reveal a noticeable positive climate-carbon cycle feedback, which is mainly driven by the tropical land biosphere. The oceans contribute much less to the positive feedback and the temperate/boreal terrestrial biosphere induces a minor negative feedback. The contrasting behavior of the tropical and temperate/boreal land biosphere is mostly attributed to opposite trends in their net primary productivity (NPP) under global warming conditions. As these findings depend on the model employed they are compared with results derived from other climate-carbon cycle models, which participated in the Coupled Climate-Carbon Cycle Model Intercomparison Project (C4MIP). (orig.)

  4. Influence of the Asian Monsoon on net ecosystem carbon exchange in two major plant functional types in Korea

    Directory of Open Access Journals (Sweden)

    H. Kwon

    2009-11-01

    Full Text Available Considering the feedback loops in radiation, temperature, and soil moisture with alterations in rainfall patterns, the influence of the changing monsoon on net ecosystem CO2 exchange can be critical to the estimation of carbon balance in Asia. In this paper, we examined the eddy covariance CO2 fluxes observed from 2004 to 2008 in two major plant functional types in KoFlux, i.e., the Gwangneung deciduous forest (GDK site and the Haenam farmland (HFK site. The objectives of the study were to (1 quantify the net ecosystem CO2 exchange (NEE, ecosystem respiration (RE, and gross primary production (GPP, (2 examine their interannual patterns, and (3 assess the mechanism for the coupling of carbon and water exchange associated with the summer monsoon. The GDK site, which had a maximum leaf area index (LAI of ~5, was on average a relatively weak carbon sink with NEE of −84 gC m−2 y−1, RE of 1028 gC m−2 y−1, and GPP of 1113 gC m−2 y−1. Despite about 20% larger GPP (of 1321 gC m−2 y−1 in comparison with the GDK site, the HFK site (with the maximum LAI of 3 to 4 was a weaker carbon sink with NEE of −58 gC m−2 y−1 because of greater RE of 1263 gC m−2 y−1. In both sites, the annual patterns of NEE and GPP had a striking "mid-season depression" each year with two distinctive peaks of different timing and magnitude, whereas RE did not. The mid-season depression at the GDK site occurred typically from early June to late August, coinciding with the season of summer monsoon when the solar radiation decreased substantially due to frequent rainfalls and cloudiness. At the HFK site, the mid-season depression began earlier in May and continued until the end of July due to land use management (e.g., crop rotation in addition to such disturbances as summer monsoon and typhoons

  5. Net farm income and land use under a U.S. greenhouse gas cap and trade

    Science.gov (United States)

    Justin S. Baker; Bruce A. McCarl; Brian C. Murray; Steven K. Rose; Ralph J. Alig; Darius Adams; Greg Latta; Robert Beach; Adam. Daigneault

    2010-01-01

    During recent years, the U.S. agricultural sector has experienced high prices for energy related inputs and commodities, and a rapidly developing bioenergy market. Greenhouse gas (GHG) emissions mitigation would further alter agricultural markets and increase land competition in forestry and agriculture by shifting input costs, creating an agricultural GHG abatement...

  6. Implication of Land-Use and Land-Cover Change into Carbon Dioxide Emissions in Karang Gading and Langkat Timur Wildlife Reserve, North Sumatra, Indonesia

    Directory of Open Access Journals (Sweden)

    Mohammad Basyuni

    2015-06-01

    Full Text Available Mangrove forest in the context of climate change is important sector to be included in the inventory of greenhouse gas (GHG emissions. The present study describes land-use and land-cover change during 2006–2012 of a mangrove forest conservation area, Karang Gading and Langkat Timur Laut Wildlife Reserve (KGLTLWR in North Sumatra, Indonesia and their implications to carbon dioxide emissions. A land-use change matrix showed that the decrease of mangrove forest due to increases of other land-use such as aquaculture (50.00% and oil palm plantation (28.83%. Furthermore, the net cumulative of carbon emissions in KGLTLWR for 2006 was 3804.70 t CO2-eq year-1, whereas predicting future emissions in 2030 was 11,318.74 t CO2-eq year-1 or an increase of 33.61% for 12 years. Source of historical emissions mainly from changes of secondary mangrove forests into aquaculture and oil palm plantation were 3223.9 t CO2-eq year-1 (84.73% and 959.00 t CO2-eq year-1 (25.21%, respectively, indicating that the KGLTLWR is still a GHG emitter. Mitigation scenario with no conversion in secondary mangrove forest reduced 16.21% and 25.8% carbon emissions in 2024 and 2030, respectively. This study suggested that aquaculture and oil palm plantation are drivers of deforestation as well as the largest of GHG emission source in this area. Keywords: carbon emission, climate change, deforestation, forest degradation, mangrove conservation

  7. Land Cover Differences in Soil Carbon and Nitrogen at Fort Benning, Georgia

    Energy Technology Data Exchange (ETDEWEB)

    Garten Jr., C.T.

    2004-02-09

    Land cover characterization might help land managers assess the impacts of management practices and land cover change on attributes linked to the maintenance and/or recovery of soil quality. However, connections between land cover and measures of soil quality are not well established. The objective of this limited investigation was to examine differences in soil carbon and nitrogen among various land cover types at Fort Benning, Georgia. Forty-one sampling sites were classified into five major land cover types: deciduous forest, mixed forest, evergreen forest or plantation, transitional herbaceous vegetation, and barren land. Key measures of soil quality (including mineral soil density, nitrogen availability, soil carbon and nitrogen stocks, as well as properties and chemistry of the O-horizon) were significantly different among the five land covers. In general, barren land had the poorest soil quality. Barren land, created through disturbance by tracked vehicles and/or erosion, had significantly greater soil density and a substantial loss of carbon and nitrogen relative to soils at less disturbed sites. We estimate that recovery of soil carbon under barren land at Fort Benning to current day levels under transitional vegetation or forests would require about 60 years following reestablishment of vegetation. Maps of soil carbon and nitrogen were produced for Fort Benning based on a 1999 land cover map and field measurements of soil carbon and nitrogen stocks under different land cover categories.

  8. Evaluating land cover influences on model uncertainties—A case study of cropland carbon dynamics in the Mid-Continent Intensive Campaign region

    Science.gov (United States)

    Li, Zhengpeng; Liu, Shuguang; Zhang, Xuesong; West, Tristram O.; Ogle, Stephen M.; Zhou, Naijun

    2016-01-01

    Quantifying spatial and temporal patterns of carbon sources and sinks and their uncertainties across agriculture-dominated areas remains challenging for understanding regional carbon cycles. Characteristics of local land cover inputs could impact the regional carbon estimates but the effect has not been fully evaluated in the past. Within the North American Carbon Program Mid-Continent Intensive (MCI) Campaign, three models were developed to estimate carbon fluxes on croplands: an inventory-based model, the Environmental Policy Integrated Climate (EPIC) model, and the General Ensemble biogeochemical Modeling System (GEMS) model. They all provided estimates of three major carbon fluxes on cropland: net primary production (NPP), net ecosystem production (NEP), and soil organic carbon (SOC) change. Using data mining and spatial statistics, we studied the spatial distribution of the carbon fluxes uncertainties and the relationships between the uncertainties and the land cover characteristics. Results indicated that uncertainties for all three carbon fluxes were not randomly distributed, but instead formed multiple clusters within the MCI region. We investigated the impacts of three land cover characteristics on the fluxes uncertainties: cropland percentage, cropland richness and cropland diversity. The results indicated that cropland percentage significantly influenced the uncertainties of NPP and NEP, but not on the uncertainties of SOC change. Greater uncertainties of NPP and NEP were found in counties with small cropland percentage than the counties with large cropland percentage. Cropland species richness and diversity also showed negative correlations with the model uncertainties. Our study demonstrated that the land cover characteristics contributed to the uncertainties of regional carbon fluxes estimates. The approaches we used in this study can be applied to other ecosystem models to identify the areas with high uncertainties and where models can be improved to

  9. Energy consumption and net CO2 sequestration of aqueous mineral carbonation

    Energy Technology Data Exchange (ETDEWEB)

    Huijgen, W.J.J.; Ruijg, G.J.; Comans, R.N.J. [ECN Biomass, Coal and Environmental Research, Petten (Netherlands); Witkamp, G.J. [Laboratory for Process Equipment, Delft University of Technology, Delft (Netherlands)

    2006-12-15

    Aqueous mineral carbonation is a potentially attractive sequestration technology to reduce CO2 emissions. The energy consumption of this technology, however, reduces the net amount of CO2 sequestered. Therefore, the energetic CO2 sequestration efficiency of aqueous mineral carbonation was studied in dependence of various process variables using either wollastonite (CaSiO3) or steel slag as feedstock. For wollastonite, the maximum energetic CO2 sequestration efficiency within the ranges of process conditions studied was 75% at 200C, 20 bar CO2, and a particle size of <38{mu}m. The main energy-consuming process steps were the grinding of the feedstock and the compression of the CO2 feed. At these process conditions, a significantly lower efficiency was determined for steel slag (69%), mainly because of the lower Ca content of the feedstock. The CO2 sequestration efficiency might be improved substantially for both types of feedstock by, e.g., reducing the amount of process water applied and further grinding of the feedstock. The calculated energetic efficiencies warrant a further assessment of the (energetic) feasibility of CO2 sequestration by aqueous mineral carbonation on the basis of a pilot-scale process.

  10. Sea spray geoengineering can reduce ocean net primary productivity and carbon uptake

    Science.gov (United States)

    Partanen, Antti-Ilari; Keller, David; Korhonen, Hannele; Matthews, Damon

    2016-04-01

    Sea spray geoengineering or marine cloud brightening is one of the proposed methods to deliberately increase planetary albedo and thus counteract climate change. Previous studies have shown that it has potential to significantly alter the global energy balance and reduce impacts on temperature and precipitation. However, its effects on ecosystems have received considerably less attention. Our goal is to assess the effects of sea spray geoengineering on marine biological productivity and global carbon cycle. We use the University of Victoria Earth System Climate Model (UVic ESCM) to simulate the effects of prescribed aerosol forcing from previous simulations with the aerosol-climate model ECHAM-HAMMOZ. In our baseline simulation (GEO), forcing from geoengineering was applied over three persistent stratocumulus regions off the coasts of North America, South America, and South Africa. The global mean forcing was -1 W m-2. Other forcings and emissions were set according to the RCP4.5 scenario. The control run (CTRL) was identical to GEO except that no geoengineering was present. As a more extreme case, we simulated a scenario where forcing from geoengineering was applied over all ocean area (GEO-ALL) giving a global mean forcing of -4.9 W m-2. Geoengineering decreased the global total ocean net primary productivity (NPP) during the first decades, but the effect was insignificant by the end of the 21st century. The decrease was caused by decreased temperature of the ocean and climate system in general, not by the decrease in available sunlight as might have been expected. This was demonstrated by two sensitivity simulations where geoengineering was affecting only either temperature or the light available to marine ecosystems. The simulation GEO-ALL behaves in a different way than GEO: ocean NPP was lower than that in CTRL for the first three decades of geoengineering as in GEO, but then NPP increased over the level in CTRL for the remaining of the simulation. In

  11. Importance of soil thermal dynamics on land carbon sequestration in Northern Eurasia during the 21st century

    Science.gov (United States)

    Kicklighter, David; Monier, Erwan; Sokolov, Andrei; Zhuang, Qianlai; Melillo, Jerry

    2015-04-01

    Recent modeling studies have suggested that carbon sinks in pan-arctic ecosystems may be weakening partially as a result of warming-induced increases in soil organic matter (SOM) decomposition and the exposure of previously frozen SOM to decomposition. This weakening of carbon sinks is likely to continue in the future as vast amount of carbon in permafrost soils is vulnerable to thaw. Here, we examine the importance of considering soil thermal dynamics when determining the effects of climate change and land-use change on carbon dynamics in Northern Eurasia during the 21st century. This importance is assessed by comparing results for a "business as usual" scenario between a version of the Terrestrial Ecosystem Model that does not consider soil thermal dynamics (TEM 4.4) and a version that does consider these dynamics (TEM 6.0). In this scenario, which is similar to the IPCC Representative Concentration Pathways (RCP) 8.5 scenario, the net area covered by food crops and pastures in Northern Eurasia is assumed to remain relatively constant over the 21st century, but the area covered by secondary forests is projected to double as a result of timber harvest and the abandonment of land associated with displacement of agricultural land. Enhanced decomposition from the newly exposed SOM from permafrost thaw also increases nitrogen availability for plant production so that the loss of carbon from the enhanced decomposition is partially compensated by enhanced uptake and storage of atmospheric carbon dioxide in vegetation. Our results indicate that consideration of soil thermal dynamics have a large influence on how simulated terrestrial carbon dynamics in Northern Eurasia respond to changes in climate, atmospheric chemistry (e.g., carbon dioxide fertilization, ozone pollution, nitrogen deposition) and disturbances.

  12. Diet control on carbon isotopic composition of land snail shell carbonate

    Institute of Scientific and Technical Information of China (English)

    LIU ZongXiu; GU ZhaoYan; WU NaiQin; XU Bing

    2007-01-01

    Carbon isotope compositions for both the carbonate shells and soft bodies (organic tissue) of living land snails collected mostly from the Loess Plateau, China have been measured. The result shows that δ13C values range from -13.1‰ to -4.3‰ for the aragonite shell samples and from -26.8‰ to -18.0‰ for the soft body samples. Although the shells are enriched in 13C relative to the bodies averagely by 14.2(±0.8)‰, the shell δ13Ca values are closely correlated to the body δ13Corg values, expressed as δ13Ca = 1.021 δ13Corg + 14.38 (R = 0.965; N = 31). This relationship indicates that δ13Ca is primarily a function of the isotopic composition of the snail diets since previous studies have proved that the snail body is the same as their food in carbon isotope composition. In other words, carbon isotope compo-sition of the carbonate shell can be used as a proxy to estimate the dietary 13C abundance of the land snails. The data also support that the 13C enrichment of the carbonate shells results mainly from the equilibrium fractionations between the metabolic CO2, HCO3- in the hemolymph and shell aragonite, and partially from kinetic fractionations when snail shells form during their activity.

  13. From zeolite nets to sp(3) carbon allotropes: a topology-based multiscale theoretical study.

    Science.gov (United States)

    Baburin, Igor A; Proserpio, Davide M; Saleev, Vladimir A; Shipilova, Alexandra V

    2015-01-14

    We present a comprehensive computational study of sp(3)-carbon allotropes based on the topologies proposed for zeolites. From ≈600,000 zeolite nets we identified six new allotropes, lying by at most 0.12 eV per atom above diamond. The analysis of cages in the allotropes has revealed close structural relations to diamond and lonsdaleite phases. Besides the energetic and mechanical stability of new allotropes, three of them show band gaps by ca. 1 eV larger than that of diamond, and therefore represent an interesting technological target as hard and transparent materials. A structural relation of new allotropes to continuous random networks is pointed out and possible engineering from diamond thin films and graphene is suggested.

  14. Net changes in aboveground woody carbon stock in western juniper woodlands, 1946-1998

    Science.gov (United States)

    Strand, Eva K.; Vierling, Lee A.; Smith, Alistair M. S.; Bunting, Stephen C.

    2008-03-01

    Although regional increases in woody plant cover in semiarid ecosystems have been identified as a worldwide phenomenon affecting the global carbon budget, quantifying the impact of these vegetation shifts on C pools and fluxes is challenging. Challenges arise because woody encroachment is governed by ecological processes that occur at fine spatial resolutions (1-10 m) and, in many cases, at slow (decadal-scale) temporal rates over large areas. We therefore analyzed time series aerial photography, which exhibits both the necessary spatial precision and temporal extent, to quantify the expansion of western juniper into sagebrush steppe landscapes in southwestern Idaho. We established upper and lower bounds of aboveground woody carbon change across the landscape via two-dimensional spatial wavelet analysis, image texture analysis, and field data collection. Forty-eight 100-ha blocks across a 330,000-ha region were stratified by topography, soil characteristics, and land stewardship for analyses. Across the area we estimate aboveground woody carbon accumulation rates of 3.3 gCm-2yr-1 and 10.0 gCm-2yr-1 using the wavelet and texture method, respectively, during the time period 1946-1998. Carbon accumulation rates were significantly affected by soil properties and were highly dependent on the spatial and temporal scales of analysis. For example, at a 100-ha scale the aboveground carbon accumulation varied from -1.7 to 9.9 gCm-2yr-1, while at the 1-ha scale the range of variability increased to -11 to 22 gCm-2yr-1. These values are an order of magnitude lower than those previously suggested due to woody encroachment, highlighting the need for examining multiple spatial scales when accounting for changes in terrestrial carbon storage.

  15. Contemporary mire net ecosystem carbon balance - controls and susceptibility to change (Invited)

    Science.gov (United States)

    Nilsson, M. B.

    2013-12-01

    In this presentation I will address three main issues: 1 - The relative importance of the component carbon (C) fluxes for the annual mire Net Ecosystem Carbon Balance (NECB); 2 - The importance of gross primary production (GPP) versus ecosystem respiration (Reco) for the annual Net Ecosystem Exchange (NEE) and finally; 3) the degree of consistency or inconsistency in how controlling factors affects NEE of different mire types. The annual mire NECB is made up principally by the biosphere-atmosphere exchange of CO2 (NEE) and CH4 and the runoff C-export. One important research issue is to further understand what controls the relative contribution from the component fluxes to the annual mire NECB. A second important major research issue is to reveal the relative importance of gross photosynthesis (GPP) and ecosystem respiration (Reco) respectively for the annual mire NEE. The relative importance of GPP and Reco respectively for the NECB also encounters the effect of changes in the lengths of the growing season and non-growing season respectively. The general understanding is that the low rate of decomposition constitutes the major control on peat accumulation. There is though growing evidences from estimates of contemporary annual as well as growing season NEE and peat core based estimates of long-term C accumulation that GPP is at least as important for the annual NEE. Finally, I will address the question to what extent different mire types respond differently to controlling e.g. if bogs and fens respond differently. Recent empirical as well as modeling studies indicate that e.g. changes in water table level causes contrasting response in NEE between bogs and fens.

  16. Ignoring detailed fast-changing dynamics of land use overestimates regional terrestrial carbon sequestration

    Directory of Open Access Journals (Sweden)

    S. Zhao

    2009-03-01

    Full Text Available Land use change is critical in determining the distribution, magnitude and mechanisms of terrestrial carbon budgets at the local to global scales. To date, almost all regional to global carbon cycle studies are driven by a static land use map or land use change statistics with decadal time intervals. The biases in quantifying carbon exchange between the terrestrial ecosystems and the atmosphere caused by using such land use change information have not been investigated. Here, we used the General Ensemble biogeochemical Modeling System (GEMS, along with consistent and spatially explicit land use change scenarios with different intervals (1 yr, 5 yrs, 10 yrs and static, respectively, to evaluate the impacts of land use change data frequency on estimating regional carbon sequestration in the southeastern United States. Our results indicate that ignoring the detailed fast-changing dynamics of land use can lead to a significant overestimation of carbon uptake by the terrestrial ecosystem. Regional carbon sequestration increased from 0.27 to 0.69, 0.80 and 0.97 Mg C ha−1 yr−1 when land use change data frequency shifting from 1 year to 5 years, 10 years interval and static land use information, respectively. Carbon removal by forest harvesting and prolonged cumulative impacts of historical land use change on carbon cycle accounted for the differences in carbon sequestration between static and dynamic land use change scenarios. The results suggest that it is critical to incorporate the detailed dynamics of land use change into local to global carbon cycle studies. Otherwise, it is impossible to accurately quantify the geographic distributions, magnitudes, and mechanisms of terrestrial carbon sequestration at local to global scales.

  17. The net benefits of human-ignited wildfire forecasting: the case of Tribal land units in the United States.

    Science.gov (United States)

    Prestemon, Jeffrey P; Butry, David T; Thomas, Douglas S

    2016-01-01

    Research shows that some categories of human-ignited wildfires might be forecastable, due to their temporal clustering, with the possibility that resources could be pre-deployed to help reduce the incidence of such wildfires. We estimated several kinds of incendiary and other human-ignited wildfire forecast models at the weekly time step for tribal land units in the United States, evaluating their forecast skill out of sample. Analyses show that an Autoregressive Conditional Poisson (ACP) model of both incendiary and non-incendiary human-ignited wildfires is more accurate out of sample compared to alternatives, and the simplest of the ACP models performed the best. Additionally, an ensemble of these and simpler, less analytically intensive approaches performed even better. Wildfire hotspot forecast models using all model types were evaluated in a simulation mode to assess the net benefits of forecasts in the context of law enforcement resource reallocations. Our analyses show that such hotspot tools could yield large positive net benefits for the tribes in terms of suppression expenditures averted for incendiary wildfires but that the hotspot tools were less likely to be beneficial for addressing outbreaks of non-incendiary human-ignited wildfires.

  18. Land-use and carbon cycle responses to moderate climate change: implications for land-based mitigation?

    Science.gov (United States)

    Humpenöder, Florian; Popp, Alexander; Stevanovic, Miodrag; Müller, Christoph; Bodirsky, Benjamin Leon; Bonsch, Markus; Dietrich, Jan Philipp; Lotze-Campen, Hermann; Weindl, Isabelle; Biewald, Anne; Rolinski, Susanne

    2015-06-02

    Climate change has impacts on agricultural yields, which could alter cropland requirements and hence deforestation rates. Thus, land-use responses to climate change might influence terrestrial carbon stocks. Moreover, climate change could alter the carbon storage capacity of the terrestrial biosphere and hence the land-based mitigation potential. We use a global spatially explicit economic land-use optimization model to (a) estimate the mitigation potential of a climate policy that provides economic incentives for carbon stock conservation and enhancement, (b) simulate land-use and carbon cycle responses to moderate climate change (RCP2.6), and (c) investigate the combined effects throughout the 21st century. The climate policy immediately stops deforestation and strongly increases afforestation, resulting in a global mitigation potential of 191 GtC in 2100. Climate change increases terrestrial carbon stocks not only directly through enhanced carbon sequestration (62 GtC by 2100) but also indirectly through less deforestation due to higher crop yields (16 GtC by 2100). However, such beneficial climate impacts increase the potential of the climate policy only marginally, as the potential is already large under static climatic conditions. In the broader picture, this study highlights the importance of land-use dynamics for modeling carbon cycle responses to climate change in integrated assessment modeling.

  19. Distinguishing the drivers of trends in land carbon fluxes and plant volatile emissions over the past three decades

    Directory of Open Access Journals (Sweden)

    X. Yue

    2015-08-01

    Full Text Available The terrestrial biosphere has experienced dramatic changes in recent decades. Estimates of historical trends in land carbon fluxes remain uncertain because long-term observations are limited on the global scale. Here, we use the Yale Interactive terrestrial Biosphere (YIBs model to estimate decadal trends in land carbon fluxes and emissions of biogenic volatile organic compounds (BVOCs and to identify the key drivers for these changes during 1982–2011. Driven with hourly meteorology from WFDEI (WATCH Forcing Data methodology applied to ERA-Interim data, the model simulates an increasing trend of 297 Tg C a−2 in gross primary productivity (GPP and 185 Tg C a−2 in the net primary productivity (NPP. CO2 fertilization is the main driver for the flux changes in forest ecosystems, while meteorology dominates the changes in grasslands and shrublands. Warming boosts summer GPP and NPP at high latitudes, while drought dampens carbon uptake in tropical regions. North of 30° N, increasing temperatures induce a substantial extension of 0.22 day a−1 for the growing season; however, this phenological change alone does not promote regional carbon uptake and BVOC emissions. Nevertheless, increases of LAI at peak season accounts for ~ 25 % of the trends in GPP and isoprene emissions at the northern lands. The net land sink shows statistically insignificant increases of only 3 Tg C a−2 globally because of simultaneous increases in soil respiration. In contrast, driven with alternative meteorology from MERRA (Modern Era-Retrospective Analysis, the model predicts significant increases of 59 Tg C a−2 in the land sink due to strengthened uptake in the Amazon. Global BVOC emissions are calculated using two schemes. With the photosynthesis-dependent scheme, the model predicts increases of 0.4 Tg C a−2 in isoprene emissions, which are mainly attributed to warming trends because CO2 fertilization and inhibition effects offset each other. Using the MEGAN

  20. Distinguishing the drivers of trends in land carbon fluxes and plant volatile emissions over the past three decades

    Science.gov (United States)

    Yue, X.; Unger, N.; Zheng, Y.

    2015-08-01

    The terrestrial biosphere has experienced dramatic changes in recent decades. Estimates of historical trends in land carbon fluxes remain uncertain because long-term observations are limited on the global scale. Here, we use the Yale Interactive terrestrial Biosphere (YIBs) model to estimate decadal trends in land carbon fluxes and emissions of biogenic volatile organic compounds (BVOCs) and to identify the key drivers for these changes during 1982-2011. Driven with hourly meteorology from WFDEI (WATCH Forcing Data methodology applied to ERA-Interim data), the model simulates an increasing trend of 297 Tg C a-2 in gross primary productivity (GPP) and 185 Tg C a-2 in the net primary productivity (NPP). CO2 fertilization is the main driver for the flux changes in forest ecosystems, while meteorology dominates the changes in grasslands and shrublands. Warming boosts summer GPP and NPP at high latitudes, while drought dampens carbon uptake in tropical regions. North of 30° N, increasing temperatures induce a substantial extension of 0.22 day a-1 for the growing season; however, this phenological change alone does not promote regional carbon uptake and BVOC emissions. Nevertheless, increases of LAI at peak season accounts for ~ 25 % of the trends in GPP and isoprene emissions at the northern lands. The net land sink shows statistically insignificant increases of only 3 Tg C a-2 globally because of simultaneous increases in soil respiration. In contrast, driven with alternative meteorology from MERRA (Modern Era-Retrospective Analysis), the model predicts significant increases of 59 Tg C a-2 in the land sink due to strengthened uptake in the Amazon. Global BVOC emissions are calculated using two schemes. With the photosynthesis-dependent scheme, the model predicts increases of 0.4 Tg C a-2 in isoprene emissions, which are mainly attributed to warming trends because CO2 fertilization and inhibition effects offset each other. Using the MEGAN (Model of Emissions of Gases

  1. Baseline Assessment of Net Calcium Carbonate Accretion Rates on U.S. Pacific Reefs.

    Directory of Open Access Journals (Sweden)

    Bernardo Vargas-Ángel

    Full Text Available This paper presents a comprehensive quantitative baseline assessment of in situ net calcium carbonate accretion rates (g CaCO3 cm(-2 yr(-1 of early successional recruitment communities on Calcification Accretion Unit (CAU plates deployed on coral reefs at 78 discrete sites, across 11 islands in the central and south Pacific Oceans. Accretion rates varied substantially within and between islands, reef zones, levels of wave exposure, and island geomorphology. For forereef sites, mean accretion rates were the highest at Rose Atoll, Jarvis, and Swains Islands, and the lowest at Johnston Atoll and Tutuila. A comparison between reef zones showed higher accretion rates on forereefs compared to lagoon sites; mean accretion rates were also higher on windward than leeward sites but only for a subset of islands. High levels of spatial variability in net carbonate accretion rates reported herein draw attention to the heterogeneity of the community assemblages. Percent cover of key early successional taxa on CAU plates did not reflect that of the mature communities present on surrounding benthos, possibly due to the short deployment period (2 years of the experimental units. Yet, net CaCO3 accretion rates were positively correlated with crustose coralline algae (CCA percent cover on the surrounding benthos and on the CAU plates, which on average represented >70% of the accreted material. For foreeefs and lagoon sites combined CaCO3 accretion rates were statistically correlated with total alkalinity and Chlorophyll-a; a GAM analysis indicated that SiOH and Halimeda were the best predictor variables of accretion rates on lagoon sites, and total alkalinity and Chlorophyll-a for forereef sites, demonstrating the utility of CAUs as a tool to monitor changes in reef accretion rates as they relate to ocean acidification. This study underscores the pivotal role CCA play as a key benthic component and supporting actively calcifying reefs; high Mg-calcite exoskeletons

  2. Baseline Assessment of Net Calcium Carbonate Accretion Rates on U.S. Pacific Reefs.

    Science.gov (United States)

    Vargas-Ángel, Bernardo; Richards, Cristi L; Vroom, Peter S; Price, Nichole N; Schils, Tom; Young, Charles W; Smith, Jennifer; Johnson, Maggie D; Brainard, Russell E

    2015-01-01

    This paper presents a comprehensive quantitative baseline assessment of in situ net calcium carbonate accretion rates (g CaCO3 cm(-2) yr(-1)) of early successional recruitment communities on Calcification Accretion Unit (CAU) plates deployed on coral reefs at 78 discrete sites, across 11 islands in the central and south Pacific Oceans. Accretion rates varied substantially within and between islands, reef zones, levels of wave exposure, and island geomorphology. For forereef sites, mean accretion rates were the highest at Rose Atoll, Jarvis, and Swains Islands, and the lowest at Johnston Atoll and Tutuila. A comparison between reef zones showed higher accretion rates on forereefs compared to lagoon sites; mean accretion rates were also higher on windward than leeward sites but only for a subset of islands. High levels of spatial variability in net carbonate accretion rates reported herein draw attention to the heterogeneity of the community assemblages. Percent cover of key early successional taxa on CAU plates did not reflect that of the mature communities present on surrounding benthos, possibly due to the short deployment period (2 years) of the experimental units. Yet, net CaCO3 accretion rates were positively correlated with crustose coralline algae (CCA) percent cover on the surrounding benthos and on the CAU plates, which on average represented >70% of the accreted material. For foreeefs and lagoon sites combined CaCO3 accretion rates were statistically correlated with total alkalinity and Chlorophyll-a; a GAM analysis indicated that SiOH and Halimeda were the best predictor variables of accretion rates on lagoon sites, and total alkalinity and Chlorophyll-a for forereef sites, demonstrating the utility of CAUs as a tool to monitor changes in reef accretion rates as they relate to ocean acidification. This study underscores the pivotal role CCA play as a key benthic component and supporting actively calcifying reefs; high Mg-calcite exoskeletons makes CCA

  3. Nutrient limitation reduces land carbon uptake in simulations with a model of combined carbon, nitrogen and phosphorus cycling

    Directory of Open Access Journals (Sweden)

    D. S. Goll

    2012-09-01

    Full Text Available Terrestrial carbon (C cycle models applied for climate projections simulate a strong increase in net primary productivity (NPP due to elevated atmospheric CO2 concentration during the 21st century. These models usually neglect the limited availability of nitrogen (N and phosphorus (P, nutrients that commonly limit plant growth and soil carbon turnover. To investigate how the projected C sequestration is altered when stoichiometric constraints on C cycling are considered, we incorporated a P cycle into the land surface model JSBACH (Jena Scheme for Biosphere–Atmosphere Coupling in Hamburg, which already includes representations of coupled C and N cycles.

    The model reveals a distinct geographic pattern of P and N limitation. Under the SRES (Special Report on Emissions Scenarios A1B scenario, the accumulated land C uptake between 1860 and 2100 is 13% (particularly at high latitudes and 16% (particularly at low latitudes lower in simulations with N and P cycling, respectively, than in simulations without nutrient cycles. The combined effect of both nutrients reduces land C uptake by 25% compared to simulations without N or P cycling. Nutrient limitation in general may be biased by the model simplicity, but the ranking of limitations is robust against the parameterization and the inflexibility of stoichiometry. After 2100, increased temperature and high CO2 concentration cause a shift from N to P limitation at high latitudes, while nutrient limitation in the tropics declines. The increase in P limitation at high-latitudes is induced by a strong increase in NPP and the low P sorption capacity of soils, while a decline in tropical NPP due to high autotrophic respiration rates alleviates N and P limitations. The quantification of P limitation remains challenging. The poorly constrained processes of soil P sorption and biochemical mineralization are identified as the main uncertainties in the strength of P limitation

  4. Sub-grid scale representation of vegetation in global land surface schemes: implications for estimation of the terrestrial carbon sink

    Directory of Open Access Journals (Sweden)

    J. R. Melton

    2014-02-01

    Full Text Available Terrestrial ecosystem models commonly represent vegetation in terms of plant functional types (PFTs and use their vegetation attributes in calculations of the energy and water balance as well as to investigate the terrestrial carbon cycle. Sub-grid scale variability of PFTs in these models is represented using different approaches with the "composite" and "mosaic" approaches being the two end-members. The impact of these two approaches on the global carbon balance has been investigated with the Canadian Terrestrial Ecosystem Model (CTEM v 1.2 coupled to the Canadian Land Surface Scheme (CLASS v 3.6. In the composite (single-tile approach, the vegetation attributes of different PFTs present in a grid cell are aggregated and used in calculations to determine the resulting physical environmental conditions (soil moisture, soil temperature, etc. that are common to all PFTs. In the mosaic (multi-tile approach, energy and water balance calculations are performed separately for each PFT tile and each tile's physical land surface environmental conditions evolve independently. Pre-industrial equilibrium CLASS-CTEM simulations yield global totals of vegetation biomass, net primary productivity, and soil carbon that compare reasonably well with observation-based estimates and differ by less than 5% between the mosaic and composite configurations. However, on a regional scale the two approaches can differ by > 30%, especially in areas with high heterogeneity in land cover. Simulations over the historical period (1959–2005 show different responses to evolving climate and carbon dioxide concentrations from the two approaches. The cumulative global terrestrial carbon sink estimated over the 1959–2005 period (excluding land use change (LUC effects differs by around 5% between the two approaches (96.3 and 101.3 Pg, for the mosaic and composite approaches, respectively and compares well with the observation-based estimate of 82.2 ± 35 Pg C over the same

  5. Divergent predictions of carbon storage between two global land models: attribution of the causes through traceability analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rafique, Rashid; Xia, Jianyang; Hararuk, Oleksandra; Asrar, Ghassem R.; Wang, Yingping; Luo, Yiqi

    2015-08-27

    Representations of the terrestrial carbon cycle in land models are becoming increasingly complex. It is crucial to develop approaches for critical assessment of the complex model properties in order to understand key factors contributing to models’ performance. In this study, we applied a traceability analysis, which decomposes carbon cycle models into traceable components, to two global land models (CABLE and CLM-CASA’) to diagnose the causes of their differences in simulating ecosystem carbon storage capacity. Driven with similar forcing data, the CLM-CASA’ model predicted ~31% larger carbon storage capacity than the CABLE model. Since ecosystem carbon storage capacity is a product of net primary productivity (NPP) and ecosystem residence time (τE), the predicted difference in the storage capacity between the two models results from differences in either NPP or τE or both. Our analysis showed that CLM-CASA’ simulated 37% higher NPP than CABLE due to higher rates of carboxylation (Vcmax) in CLM-CASA’. On the other hand, τE , which was a function the baseline carbon residence time (τ´E) and environmental effect on carbon residence time, was on average 11 years longer in CABLE than CLM-CASA’. The difference in τE was mainly found to be caused by longer τ´E in CABLE than CLM-CASA’. This difference in τE was mainly caused by longer τ´E of woody biomass (23 vs. 14 years in CLM-CASA’) and higher proportion of NPP allocated to woody biomass (23% vs. 16%). Differences in environmental effects on carbon residence times had smaller influences on differences in ecosystem carbon storage capacities compared to differences in NPP and τ´E. Overall; the traceability analysis is an effective method for identifying sources of variations between the two models.

  6. Can Switching from Coal to Shale Gas Bring Net Carbon Reductions to China?

    Science.gov (United States)

    Qin, Yue; Edwards, Ryan; Tong, Fan; Mauzerall, Denise L

    2017-02-21

    To increase energy security and reduce emissions of air pollutants and CO2 from coal use, China is attempting to duplicate the rapid development of shale gas that has taken place in the United States. This work builds a framework to estimate the lifecycle greenhouse gas (GHG) emissions from China's shale gas system and compares them with GHG emissions from coal used in the power, residential, and industrial sectors. We find the mean lifecycle carbon footprint of shale gas is about 30-50% lower than that of coal in all sectors under both 20 year and 100 year global warming potentials (GWP20 and GWP100). However, primarily due to large uncertainties in methane leakage, the upper bound estimate of the lifecycle carbon footprint of shale gas in China could be approximately 15-60% higher than that of coal across sectors under GWP20. To ensure net GHG emission reductions when switching from coal to shale gas, we estimate the breakeven methane leakage rates to be approximately 6.0%, 7.7%, and 4.2% in the power, residential, and industrial sectors, respectively, under GWP20. We find shale gas in China has a good chance of delivering air quality and climate cobenefits, particularly when used in the residential sector, with proper methane leakage control.

  7. Convergent Evolution towards High Net Carbon Gain Efficiency Contributes to the Shade Tolerance of Palms (Arecaceae).

    Science.gov (United States)

    Ma, Ren-Yi; Zhang, Jiao-Lin; Cavaleri, Molly A; Sterck, Frank; Strijk, Joeri S; Cao, Kun-Fang

    2015-01-01

    Most palm species occur in the shaded lower strata of tropical rain forests, but how their traits relate to shade adaptation is poorly understood. We hypothesized that palms are adapted to the shade of their native habitats by convergent evolution towards high net carbon gain efficiency (CGEn), which is given by the maximum photosynthetic rate to dark respiration rate ratio. Leaf mass per area, maximum photosynthetic rate, dark respiration and N and P concentrations were measured in 80 palm species grown in a common garden, and combined with data of 30 palm species growing in their native habitats. Compared to other species from the global leaf economics data, dicotyledonous broad-leaved trees in tropical rainforest or other monocots in the global leaf economics data, palms possessed consistently higher CGEn, achieved by lowered dark respiration and fairly high foliar P concentration. Combined phylogenetic analyses of evolutionary signal and trait evolution revealed convergent evolution towards high CGEn in palms. We conclude that high CGEn is an evolutionary strategy that enables palms to better adapt to shady environments than coexisting dicot tree species, and may convey advantages in competing with them in the tropical forest understory. These findings provide important insights for understanding the evolution and ecology of palms, and for understanding plant shade adaptations of lower rainforest strata. Moreover, given the dominant role of palms in tropical forests, these findings are important for modelling carbon and nutrient cycling in tropical forest ecosystems.

  8. Convergent Evolution towards High Net Carbon Gain Efficiency Contributes to the Shade Tolerance of Palms (Arecaceae.

    Directory of Open Access Journals (Sweden)

    Ren-Yi Ma

    Full Text Available Most palm species occur in the shaded lower strata of tropical rain forests, but how their traits relate to shade adaptation is poorly understood. We hypothesized that palms are adapted to the shade of their native habitats by convergent evolution towards high net carbon gain efficiency (CGEn, which is given by the maximum photosynthetic rate to dark respiration rate ratio. Leaf mass per area, maximum photosynthetic rate, dark respiration and N and P concentrations were measured in 80 palm species grown in a common garden, and combined with data of 30 palm species growing in their native habitats. Compared to other species from the global leaf economics data, dicotyledonous broad-leaved trees in tropical rainforest or other monocots in the global leaf economics data, palms possessed consistently higher CGEn, achieved by lowered dark respiration and fairly high foliar P concentration. Combined phylogenetic analyses of evolutionary signal and trait evolution revealed convergent evolution towards high CGEn in palms. We conclude that high CGEn is an evolutionary strategy that enables palms to better adapt to shady environments than coexisting dicot tree species, and may convey advantages in competing with them in the tropical forest understory. These findings provide important insights for understanding the evolution and ecology of palms, and for understanding plant shade adaptations of lower rainforest strata. Moreover, given the dominant role of palms in tropical forests, these findings are important for modelling carbon and nutrient cycling in tropical forest ecosystems.

  9. Effects of land management on large trees and carbon stocks

    Directory of Open Access Journals (Sweden)

    P. E. Kauppi

    2014-02-01

    Full Text Available Large trees are important and unique organisms in forests, providing ecosystem services including carbon dioxide removal from the atmosphere and long-term storage. There is concern about reports of global decline of big trees. Based on observations from Finland and the United States we report that trends of big trees during recent decades have been surprisingly variable among regions. In southern Finland, the growing stock volume of trees larger than 30 cm at breast height increased nearly five-fold during the second half of the 20th century, yet more recently ceased to expand. In the United States, large hardwood trees have become increasingly common since the 1950s, while large softwood trees declined until the mid 1990's as a consequence of harvests in the Pacific region, and then rebounded when harvesting there was reduced. We conclude that in the regions studied, the history of land use and forest management governs changes of tree populations especially with reference to large trees. Large trees affect greatly the carbon density of forests and usually have deeper roots and relatively lower mortality than small trees. An accumulating stock of large trees in forests may have negligible direct biophysical effects on climate because from changes in transpiration or forest albedo. Large trees have particular ecological importance and often constitute an unusually large proportion of biomass carbon stocks in a forest. Understanding the changes in big tree distributions in different regions of the world and the demography of tree populations makes a contribution to estimating the past impact and future potential of the role of forests in the global carbon budget.

  10. Effects of land management on large trees and carbon stocks

    Science.gov (United States)

    Kauppi, P. E.; Birdsey, R. A.; Pan, Y.; Ihalainen, A.; Nöjd, P.; Lehtonen, A.

    2015-02-01

    Large trees are important and unique organisms in forests, providing ecosystem services including carbon dioxide removal from the atmosphere and long-term storage. Some reports have raised concerns about the global decline of large trees. Based on observations from two regions in Finland and three regions in the United States we report that trends of large trees during recent decades have been surprisingly variable among regions. In southern Finland, the growing stock volume of trees larger than 30 cm at breast height increased nearly five-fold during the second half of the 20th century, yet more recently ceased to expand. In the United States, large hardwood trees have become increasingly common in the Northeast since the 1950s, while large softwood trees declined until the mid 1990s as a consequence of harvests in the Pacific region, and then rebounded when harvesting there was reduced. We conclude that in the regions studied, the history of land use and forest management governs changes of the diameter-class distributions of tree populations. Large trees have significant benefits; for example, they can constitute a large proportion of the carbon stock and affect greatly the carbon density of forests. Large trees usually have deeper roots and long lifetimes. They affect forest structure and function and provide habitats for other species. An accumulating stock of large trees in existing forests may have negligible direct biophysical effects on climate through transpiration or forest albedo. Understanding changes in the demography of tree populations makes a contribution to estimating the past impact and future potential of forests in the global carbon budget and to assessing other ecosystem services of forests.

  11. Environmental Control of Net Ecosystem Carbon Dioxide Exchange in Contrasting Peatlands in northern Alberta, Canada

    Science.gov (United States)

    Syed, K. H.; Carlson, P. J.; Glenn, A. J.; Flanagan, L. B.

    2004-12-01

    Peatlands cover about 21 per cent of the landscape and contain about 80 per cent of the soil carbon stock in western Canada. However, the current rates of carbon accumulation and the environmental controls on ecosystem photosynthesis and respiration in peatland ecosystems is poorly understood. As part of Fluxnet-Canada, we continuously measured net ecosystem carbon dioxide exchange (NEE) using the eddy covariance technique in a treed fen (main site) dominated by stunted black spruce and larch trees during August 2003 through July 2004. Additional NEE measurements were made at two auxiliary sites during intervals in the active growing season (May through September 2004). One auxiliary site was dominated by Sphagnum moss, while the dominant species at other site were Carex and brown mosses. The NEE measurements were used to develop statistical models to assess temporal variation in physiological parameters for ecosystem photosynthesis and respiration. Large seasonal changes occurred in maximum photosynthetic capacity and standardized ecosystem respiration rate at 10 degrees C (R10). The mid-day NEE uptake rate during July averaged 10 μ mol m-2 s-1 at the main site, while lower values of approximately 6 μ mol m-2 s-1 were observed at the two auxiliary sites. No photosynthetic activity was observed during mid-November through mid-March. On an annual basis R10 varied from less than 0.5 μ mol m-2 s-1 in the winter to approximately 3 μ mol m-2 s-1 during August at the main site. During much of the growing season, a distinct hysteresis was observed in the light (photon flux density, PFD) response curves for NEE between morning and afternoon periods. This was caused by large diurnal changes in temperature, which at times resulted in the light compensation point for NEE shifting from a PFD of 100 μ mol m-2 s-1 in the morning to 350 μ mol m-2 s-1 in the afternoon. The main site recorded a net annual gain of 160 g C m-2 yr-1, the result of a difference between gross

  12. Modeling the Net Ecosystem Carbon Balance and Net Ecosystem Exchange of Agroecosystems of the Mid-Continent Intensive Campaign Region during 2000-2008

    Science.gov (United States)

    Izaurralde, R. C.; Zhang, X.; Post, W. M.; Thomson, A. M.; West, T. O.; Williams, J. R.; Manowitz, D.; Nichols, J.; Bandaru, V.; Doraiswamy, P. C.

    2009-12-01

    The terrestrial ecosystem model EPIC (Environment Policy Integrated Climate) is used to simulate the Net Ecosystem Carbon Balance (NECB) and Net Ecosystem Exchange (NEE) in the Mid-Continent Intensive Campaign Region during 2000-2008. EPIC simulates NECB as the difference between C additions (surface and subsurface litter, organic amendments) and C losses (harvest, heterotrophic respiration, soil erosion, and leaching), and NEE as the difference between net primary productivity and heterotrophic respiration. We used the USDA Crop Data Layer to delineate croplands and pasturelands, NCEP Reanalysis data to construct weather files, the SSURGO database to build soil layer files, the NRI database to build management files, and the CTIC database to capture the evolution of tillage practices during the study period. Each site is simulated multiple times by varying input parameters in order to estimate output uncertainty. Simulations of NECB and NEE are aggregated to and reported at the county scale in order to be compared with C flux results obtained using atmospheric inversion methods.

  13. Weakening temperature control on the interannual variations of spring carbon uptake across northern lands

    Energy Technology Data Exchange (ETDEWEB)

    Piao, Shilong [Chinese Academy of Sciences (CAS), Beijing (China); Peking Univ., Beijing (China); Liu, Zhuo [Peking Univ., Beijing (China); Wang, Tao [Chinese Academy of Sciences (CAS), Beijing (China); Peng, Shushi [Peking Univ., Beijing (China); Ciais, Philippe [Alternative Energies and Atomic Energy Commission (CEA), Gif-sur-Yvette (France); Huang, Mengtian [Peking Univ., Beijing (China); Ahlstrom, Anders [Stanford Univ., CA (United States); Burkhart, John F. [Univ. of Oslo (Norway); Chevallier, Frédéric [Alternative Energies and Atomic Energy Commission (CEA), Gif-sur-Yvette (France); Janssens, Ivan A. [Univ. of Antwerp, Wilrijk (Belgium); Jeong, Su-Jong [South Univ. of Science and Technology of China, Shenzhen (China); Lin, Xin [Alternative Energies and Atomic Energy Commission (CEA), Gif-sur-Yvette (France); Mao, Jiafu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Miller, John [National Oceanic and Atmospheric Administration Earth Systems Research Lab., Boulder, CO (United States); Univ. of Colorado, Boulder, CO (United States); Mohammat, Anwar [Chinese Academy of Sciences (CAS), Beijing (China); Myneni, Ranga B. [Boston Univ., MA (United States); Peñuelas, Josep [Centre for Ecological Research and Forestry Applications (CREAF), Barcelona (Spain); Shi, Xiaoying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Stohl, Andreas [Norwegian Institute for Air Research (NILU), Kjeller (Norway); Yao, Yitong [Peking Univ., Beijing (China); Zhu, Zaichun [Peking Univ., Beijing (China); Tans, Pieter P. [National Oceanic and Atmospheric Administration Earth Systems Research Lab., Boulder, CO (United States)

    2017-04-24

    Ongoing spring warming allows the growing season to begin earlier, enhancing carbon uptake in northern ecosystems. We use 34 years of atmospheric CO2 concentration measurements at Barrow, Alaska (BRW, 71° N) to show that the interannual relationship between spring temperature and carbon uptake has recently shifted. Here, we use two indicators: the spring zero-crossing date of atmospheric CO2 (SZC) and the magnitude of CO2 drawdown between May and June (SCC). The previously reported strong correlation between SZC, SCC and spring land temperature (ST) was found in the first 17 years of measurements, but disappeared in the last 17 years. As a result, the sensitivity of both SZC and SCC to warming decreased. Simulations with an atmospheric transport model coupled to a terrestrial ecosystem model suggest that the weakened interannual correlation of SZC and SCC with ST in the last 17 years is attributable to the declining temperature response of spring net primary productivity (NPP) rather than to changes in heterotrophic respiration or in atmospheric transport patterns. Reduced chilling during dormancy and emerging light limitation are possible mechanisms that may have contributed to the loss of NPP response to ST. These results thus challenge the ‘warmer spring–bigger sink’ mechanism.

  14. Lateral transport of soil carbon and land-atmosphere CO2 flux induced by water erosion in China.

    Science.gov (United States)

    Yue, Yao; Ni, Jinren; Ciais, Philippe; Piao, Shilong; Wang, Tao; Huang, Mengtian; Borthwick, Alistair G L; Li, Tianhong; Wang, Yichu; Chappell, Adrian; Van Oost, Kristof

    2016-06-14

    Soil erosion by water impacts soil organic carbon stocks and alters CO2 fluxes exchanged with the atmosphere. The role of erosion as a net sink or source of atmospheric CO2 remains highly debated, and little information is available at scales larger than small catchments or regions. This study attempts to quantify the lateral transport of soil carbon and consequent land-atmosphere CO2 fluxes at the scale of China, where severe erosion has occurred for several decades. Based on the distribution of soil erosion rates derived from detailed national surveys and soil carbon inventories, here we show that water erosion in China displaced 180 ± 80 Mt C⋅y(-1) of soil organic carbon during the last two decades, and this resulted a net land sink for atmospheric CO2 of 45 ± 25 Mt C⋅y(-1), equivalent to 8-37% of the terrestrial carbon sink previously assessed in China. Interestingly, the "hotspots," largely distributed in mountainous regions in the most intensive sink areas (>40 g C⋅m(-2)⋅y(-1)), occupy only 1.5% of the total area suffering water erosion, but contribute 19.3% to the national erosion-induced CO2 sink. The erosion-induced CO2 sink underwent a remarkable reduction of about 16% from the middle 1990s to the early 2010s, due to diminishing erosion after the implementation of large-scale soil conservation programs. These findings demonstrate the necessity of including erosion-induced CO2 in the terrestrial budget, hence reducing the level of uncertainty.

  15. Lateral transport of soil carbon and land-atmosphere CO2 flux induced by water erosion in China

    Science.gov (United States)

    Yue, Yao; Ni, Jinren; Ciais, Philippe; Piao, Shilong; Wang, Tao; Huang, Mengtian; Borthwick, Alistair G. L.; Li, Tianhong; Wang, Yichu; Chappell, Adrian; Van Oost, Kristof

    2016-06-01

    Soil erosion by water impacts soil organic carbon stocks and alters CO2 fluxes exchanged with the atmosphere. The role of erosion as a net sink or source of atmospheric CO2 remains highly debated, and little information is available at scales larger than small catchments or regions. This study attempts to quantify the lateral transport of soil carbon and consequent land-atmosphere CO2 fluxes at the scale of China, where severe erosion has occurred for several decades. Based on the distribution of soil erosion rates derived from detailed national surveys and soil carbon inventories, here we show that water erosion in China displaced 180 ± 80 Mt Cṡy-1 of soil organic carbon during the last two decades, and this resulted a net land sink for atmospheric CO2 of 45 ± 25 Mt Cṡy-1, equivalent to 8-37% of the terrestrial carbon sink previously assessed in China. Interestingly, the “hotspots,” largely distributed in mountainous regions in the most intensive sink areas (>40 g Cṡm-2ṡy-1), occupy only 1.5% of the total area suffering water erosion, but contribute 19.3% to the national erosion-induced CO2 sink. The erosion-induced CO2 sink underwent a remarkable reduction of about 16% from the middle 1990s to the early 2010s, due to diminishing erosion after the implementation of large-scale soil conservation programs. These findings demonstrate the necessity of including erosion-induced CO2 in the terrestrial budget, hence reducing the level of uncertainty.

  16. Distinguishing the drivers of trends in land carbon fluxes and plant volatile emissions over the past 3 decades

    Science.gov (United States)

    Yue, X.; Unger, N.; Zheng, Y.

    2015-10-01

    The terrestrial biosphere has experienced dramatic changes in recent decades. Estimates of historical trends in land carbon fluxes remain uncertain because long-term observations are limited on the global scale. Here, we use the Yale Interactive terrestrial Biosphere (YIBs) model to estimate decadal trends in land carbon fluxes and emissions of biogenic volatile organic compounds (BVOCs) and to identify the key drivers for these changes during 1982-2011. Driven by hourly meteorology from WFDEI (WATCH forcing data methodology applied to ERA-Interim data), the model simulates an increasing trend of 297 Tg C a-2 in gross primary productivity (GPP) and 185 Tg C a-2 in the net primary productivity (NPP). CO2 fertilization is the main driver for the flux changes in forest ecosystems, while meteorology dominates the changes in grasslands and shrublands. Warming boosts summer GPP and NPP at high latitudes, while drought dampens carbon uptake in tropical regions. North of 30° N, increasing temperatures induce a substantial extension of 0.22 day a-1 for the growing season; however, this phenological change alone does not promote regional carbon uptake and BVOC emissions. Nevertheless, increases of leaf area index at peak season accounts for ~ 25 % of the trends in GPP and isoprene emissions at the northern lands. The net land sink shows statistically insignificant increases of only 3 Tg C a-2 globally because of simultaneous increases in soil respiration. Global BVOC emissions are calculated using two schemes. With the photosynthesis-dependent scheme, the model predicts increases of 0.4 Tg C a-2 in isoprene emissions, which are mainly attributed to warming trends because CO2 fertilization and inhibition effects offset each other. Using the MEGAN (Model of Emissions of Gases and Aerosols from Nature) scheme, the YIBs model simulates global reductions of 1.1 Tg C a-2 in isoprene and 0.04 Tg C a-2 in monoterpene emissions in response to the CO2 inhibition effects. Land use

  17. Evaluation of Carbon and Oxygen Balances in Urban Ecosystems Using Land Use/Land Cover and Statistical Data

    Directory of Open Access Journals (Sweden)

    Kai Yin

    2014-12-01

    Full Text Available Urban areas play an important role in the global carbon cycle, and human-induced carbon emissions from urban areas urgently need to be reduced. Therefore, understanding the relationship between carbon sources and sinks is the first step toward mitigating the effect of urban areas on climate change. Combined with the land use and land cover (LULC empirical coefficients and statistical methods, urban carbon and oxygen balances in Beijing were evaluated. In this study, the carbon sequestration and oxygen emission capabilities of various LULC types were calculated, and the partitioning of carbon emissions and oxygen consumption in Beijing were estimated. The evaluation results indicated that the ecosystem services from the LULC in an area were not adequate to offset the urban carbon emissions and oxygen consumption. The areas with a high capacity for carbon sequestration and oxygen emissions were primarily distributed in the exurban districts of Beijing, and the carbon and oxygen balances in the exurban districts were superior to those of core urban areas. Industrial fossil fuel consumption dominated all of the human-induced carbon sources. The methods developed in this research were shown to be viable for the quantitative evaluation of urban ecosystem carbon and oxygen balances.

  18. Assessing net ecosystem carbon exchange of U S terrestrial ecosystems by integrating eddy covariance flux measurements and satellite observations

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Qianlai [Purdue University; Law, Beverly E. [Oregon State University; Baldocchi, Dennis [University of California, Berkeley; Ma, Siyan [University of California, Berkeley; Chen, Jiquan [University of Toledo, Toledo, OH; Richardson, Andrew [Harvard University; Melillo, Jerry [Marine Biological Laboratory; Davis, Ken J. [Pennsylvania State University; Hollinger, D. [USDA Forest Service; Wharton, Sonia [University of California, Davis; Falk, Matthias [University of California, Davis; Paw, U. Kyaw Tha [University of California, Davis; Oren, Ram [Duke University; Katulk, Gabriel G. [Duke University; Noormets, Asko [North Carolina State University; Fischer, Marc [Lawrence Berkeley National Laboratory (LBNL); Verma, Shashi [University of Nebraska; Suyker, A. E. [University of Nebraska, Lincoln; Cook, David R. [Argonne National Laboratory (ANL); Sun, G. [USDA Forest Service; McNulty, Steven G. [USDA Forest Service; Wofsy, Steve [Harvard University; Bolstad, Paul V [University of Minnesota; Burns, Sean [University of Colorado, Boulder; Monson, Russell K. [University of Colorado, Boulder; Curtis, Peter [Ohio State University, The, Columbus; Drake, Bert G. [Smithsonian Environmental Research Center, Edgewater, MD; Foster, David R. [Harvard University; Gu, Lianhong [ORNL; Hadley, Julian L. [Harvard University; Litvak, Marcy [University of New Mexico, Albuquerque; Martin, Timothy A. [University of Florida, Gainesville; Matamala, Roser [Argonne National Laboratory (ANL); Meyers, Tilden [NOAA, Oak Ridge, TN; Oechel, Walter C. [San Diego State University; Schmid, H. P. [Indiana University; Scott, Russell L. [USDA ARS; Torn, Margaret S. [Lawrence Berkeley National Laboratory (LBNL)

    2011-01-01

    More accurate projections of future carbon dioxide concentrations in the atmosphere and associated climate change depend on improved scientific understanding of the terrestrial carbon cycle. Despite the consensus that U.S. terrestrial ecosystems provide a carbon sink, the size, distribution, and interannual variability of this sink remain uncertain. Here we report a terrestrial carbon sink in the conterminous U.S. at 0.63 pg C yr 1 with the majority of the sink in regions dominated by evergreen and deciduous forests and savannas. This estimate is based on our continuous estimates of net ecosystem carbon exchange (NEE) with high spatial (1 km) and temporal (8-day) resolutions derived from NEE measurements from eddy covariance flux towers and wall-to-wall satellite observations from Moderate Resolution Imaging Spectroradiometer (MODIS). We find that the U.S. terrestrial ecosystems could offset a maximum of 40% of the fossil-fuel carbon emissions. Our results show that the U.S. terrestrial carbon sink varied between 0.51 and 0.70 pg C yr 1 over the period 2001 2006. The dominant sources of interannual variation of the carbon sink included extreme climate events and disturbances. Droughts in 2002 and 2006 reduced the U.S. carbon sink by 20% relative to a normal year. Disturbances including wildfires and hurricanes reduced carbon uptake or resulted in carbon release at regional scales. Our results provide an alternative, independent, and novel constraint to the U.S. terrestrial carbon sink.

  19. Soil Organic Carbon Fractions and Stocks Respond to Restoration Measures in Degraded Lands by Water Erosion.

    Science.gov (United States)

    Nie, Xiaodong; Li, Zhongwu; Huang, Jinquan; Huang, Bin; Xiao, Haibing; Zeng, Guangming

    2017-01-11

    Assessing the degree to which degraded soils can be recovered is essential for evaluating the effects of adopted restoration measures. The objective of this study was to determine the restoration of soil organic carbon under the impact of terracing and reforestation. A small watershed with four typical restored plots (terracing and reforestation (four different local plants)) and two reference plots (slope land with natural forest (carbon-depleted) and abandoned depositional land (carbon-enriched)) in subtropical China was studied. The results showed that soil organic carbon, dissolved organic carbon and microbial biomass carbon concentrations in the surface soil (10 cm) of restored lands were close to that in abandoned depositional land and higher than that in natural forest land. There was no significant difference in soil organic carbon content among different topographic positions of the restored lands. Furthermore, the soil organic carbon stocks in the upper 60 cm soils of restored lands, which were varied between 50.08 and 62.21 Mg C ha(-1), were higher than 45.90 Mg C ha(-1) in natural forest land. Our results indicated that the terracing and reforestation could greatly increase carbon sequestration and accumulation and decrease carbon loss induced by water erosion. And the combination measures can accelerate the restoration of degraded soils when compared to natural forest only. Forest species almost have no impact on the total amount of soil organic carbon during restoration processes, but can significantly influence the activity and stability of soil organic carbon. Combination measures which can provide suitable topography and continuous soil organic carbon supply could be considered in treating degraded soils caused by water erosion.

  20. Sea and land surface temperatures, ocean heat content, Earth's energy imbalance and net radiative forcing over the last decade

    Science.gov (United States)

    Dieng, Habib B.; Cazenave, Anny; Meyssignac, Benoit; Schuckmann, Karina

    2016-04-01

    The Earth's global mean surface temperature (GMST) has increased less rapidly since the early 2000s than during the previous decades. Here we investigate the regional distribution of the reported temperature slowdown, focusing on the 2003-2014 decade of most complete global datasets. We find that both land surface temperature (LST) and sea surface temperature (SST) have increased at a rate significantly lower than over the previous decades with small regional differences. While confirming cooling of eastern tropical Pacific during the last decade, our results show that the reduced rate of change is a global phenomenon. We further evaluate the time derivative of full-depth ocean heat content to determine the planetary energy imbalance based on three different approaches: in situ measurements, ocean reanalysis and an indirect measure through the global sea level budget. For the 2003-2014 time span, it is estimated to 0.5 +/- 0.06 Wm-2, 0.64 +/- 0.04 Wm-2, and 0.6 +/- 0.07 Wm-2, respectively for the 3 approaches. We constrain the ocean heat uptake rates using the EBAF energy imbalance time series from the CERES/TOA project and find significant agreement at interannual scales. Finally, we compute the net radiative forcing of the last decade, considering the radiative feedback from observed GMST and the 3 different rates of the total ocean heat content. We obtain values of 1.6 +/- 0.19 Wm-2, 1.75 +/- 0.17 Wm-2, and 1.70 +/- 0.19 Wm-2, respectively over 2003-2014. We find no evidence of decrease in the net radiative forcing in the recent years, but rather increase compared to the previous decades.

  1. Decoupling of soil carbon and nitrogen turnover partly explains increased net ecosystem production in response to nitrogen fertilization

    Science.gov (United States)

    Ehtesham, Emad; Bengtson, Per

    2017-04-01

    During the last decade there has been an ongoing controversy regarding the extent to which nitrogen fertilization can increase carbon sequestration and net ecosystem production in forest ecosystems. The debate is complicated by the fact that increased nitrogen availability caused by nitrogen deposition has coincided with increasing atmospheric carbon dioxide concentrations. The latter could further stimulate primary production but also result in increased allocation of carbon to root exudates, which could potentially ‘prime’ the decomposition of soil organic matter. Here we show that increased input of labile carbon to forest soil caused a decoupling of soil carbon and nitrogen cycling, which was manifested as a reduction in respiration of soil organic matter that coincided with a substantial increase in gross nitrogen mineralization. An estimate of the magnitude of the effect demonstrates that the decoupling could potentially result in an increase in net ecosystem production by up to 51 kg C ha-1 day-1 in nitrogen fertilized stands during peak summer. Even if the effect is several times lower on an annual basis, the results still suggest that nitrogen fertilization can have a much stronger influence on net ecosystem production than can be expected from a direct stimulation of primary production alone.

  2. Seasonal effects of irrigation on land-atmosphere latent heat, sensible heat, and carbon fluxes in semiarid basin

    Science.gov (United States)

    Zeng, Yujin; Xie, Zhenghui; Liu, Shuang

    2017-02-01

    Irrigation, which constitutes ˜ 70 % of the total amount of freshwater consumed by the human population, is significantly impacting land-atmosphere fluxes. In this study, using the improved Community Land Model version 4.5 (CLM4.5) with an active crop model, two high-resolution (˜ 1 km) simulations investigating the effects of irrigation on latent heat (LH), sensible heat (SH), and carbon fluxes (or net ecosystem exchange, NEE) from land to atmosphere in the Heihe River basin in northwestern China were conducted using a high-quality irrigation dataset compiled from 1981 to 2013. The model output and measurements from remote sensing demonstrated the capacity of the developed models to reproduce ecological and hydrological processes. The results revealed that the effects of irrigation on LH and SH are strongest during summer, with a LH increase of ˜ 100 W m-2 and a SH decrease of ˜ 60 W m-2 over intensely irrigated areas. However, the reactions are much weaker during spring and autumn when there is much less irrigation. When the irrigation rate is below 5 mm day-1, the LH generally increases, whereas the SH decreases with growing irrigation rates. However, when the irrigation threshold is in excess of 5 mm day-1, there is no accrued effect of irrigation on the LH and SH. Irrigation produces opposite effects to the NEE during spring and summer. During the spring, irrigation yields more discharged carbon from the land to the atmosphere, increasing the NEE value by 0.4-0.8 gC m-2 day-1, while the summer irrigation favors crop fixing of carbon from atmospheric CO2, decreasing the NEE value by ˜ 0.8 gC m-2 day-1. The repercussions of irrigation on land-atmosphere fluxes are not solely linked to the irrigation amount, and other parameters (especially the temperature) also control the effects of irrigation on LH, SH, and NEE.

  3. Net ecosystem exchange of CO2 and carbon balance for eight temperate organic soils under agricultural management

    DEFF Research Database (Denmark)

    Elsgaard, Lars; Görres, C.-M.; Hoffmann, Carl Christian

    2012-01-01

    This study presents the first annual estimates of net ecosystem exchange (NEE) of CO2 and net ecosystem carbon balances (NECB) of contrasting Danish agricultural peatlands. Studies were done at eight sites representing permanent grasslands (PG) and rotational (RT) arable soils cropped to barley......, potato or forage grasses in three geo-regional settings. Using an advanced flux-chamber technique, NEE was derived from modelling of ecosystem respiration (ER) and gross primary production (GPP) with temperature and photosynthetically active radiation as driving variables. At PG (n = 3) and RT (n = 5...

  4. Fire, hurricane and carbon dioxide: effects on net primary production of a subtropical woodland.

    Science.gov (United States)

    Hungate, Bruce A; Day, Frank P; Dijkstra, Paul; Duval, Benjamin D; Hinkle, C Ross; Langley, J Adam; Megonigal, J Patrick; Stiling, Peter; Johnson, Dale W; Drake, Bert G

    2013-11-01

    Disturbance affects most terrestrial ecosystems and has the potential to shape their responses to chronic environmental change. Scrub-oak vegetation regenerating from fire disturbance in subtropical Florida was exposed to experimentally elevated carbon dioxide (CO₂) concentration (+350 μl l(-1)) using open-top chambers for 11 yr, punctuated by hurricane disturbance in year 8. Here, we report the effects of elevated CO₂ on aboveground and belowground net primary productivity (NPP) and nitrogen (N) cycling during this experiment. The stimulation of NPP and N uptake by elevated CO₂ peaked within 2 yr after disturbance by fire and hurricane, when soil nutrient availability was high. The stimulation subsequently declined and disappeared, coincident with low soil nutrient availability and with a CO₂ -induced reduction in the N concentration of oak stems. These findings show that strong growth responses to elevated CO₂ can be transient, are consistent with a progressively limited response to elevated CO₂ interrupted by disturbance, and illustrate the importance of biogeochemical responses to extreme events in modulating ecosystem responses to global environmental change.

  5. Bottom-up assessment of the Net Ecosystem Carbon Balance of Russian forests in 2010 for comparison to Top-down estimates.

    Science.gov (United States)

    Maksyutov, S. S.; Shvidenko, A.; Shchepashchenko, D.

    2014-12-01

    The verified full carbon assessment of Russian forests (FCA) is based on an Integrated Land Information System (ILIS) that includes a multi-layer and multi-scale GIS with basic resolution of 1 km and corresponding attributive databases. The ILIS aggregates all available information about ecosystems and landscapes, sets of empirical and semi-empirical data and aggregations, data of different inventories and surveys, and multi-sensor remote sensing data. The ILIS serves as an information base for application of the landscape-ecosystem approach (LEA) of the FCA and as a systems design for comparison and mutual constraints with other methods of study of carbon cycling of forest ecosystems (eddy covariance; process models; inverse modeling; and multi-sensor application of remote sensing). The LEA is based on a complimentary use of the flux-based method with some elements of the pool-based method. Introduction of climatic parameters of individual years in the LEA, as well as some process-based elements, allows providing a substantial decrease of the uncertainties of carbon cycling yearly indicators of forest ecosystems. Major carbon pools (live biomass, coarse woody debris, soil organic carbon) are estimated based on data on areas, distribution and major biometric characteristics of Russian forests presented in form of the ILIS for the country. The major fluxes accounted for include Net Primary Production (NPP), Soil Heterotrophic Respiration (SHR), as well as fluxes caused by decomposition of Coarse Woody Debris (CWD), harvest and use of forest products, fluxes caused by natural disturbances (fire, insect outbreaks, impacts of unfavorable environment) and lateral fluxes to hydrosphere and lithosphere. Use of landscape-ecosystem approach resulted in the NECB at 573±140 Tg C yr-1 (CI 0.9). While the total carbon sink is high, large forest areas, particularly on permafrost, serve as a carbon source. The ratio between net primary production and soil heterotrophic

  6. Relationship Study on Land Use Spatial Distribution Structure and Energy-Related Carbon Emission Intensity in Different Land Use Types of Guangdong, China, 1996–2008

    Directory of Open Access Journals (Sweden)

    Yi Huang

    2013-01-01

    Full Text Available This study attempts to discuss the relationship between land use spatial distribution structure and energy-related carbon emission intensity in Guangdong during 1996–2008. We quantized the spatial distribution structure of five land use types including agricultural land, industrial land, residential and commercial land, traffic land, and other land through applying spatial Lorenz curve and Gini coefficient. Then the corresponding energy-related carbon emissions in each type of land were calculated in the study period. Through building the reasonable regression models, we found that the concentration degree of industrial land is negatively correlated with carbon emission intensity in the long term, whereas the concentration degree is positively correlated with carbon emission intensity in agricultural land, residential and commercial land, traffic land, and other land. The results also indicate that land use spatial distribution structure affects carbon emission intensity more intensively than energy efficiency and production efficiency do. These conclusions provide valuable reference to develop comprehensive policies for energy conservation and carbon emission reduction in a new perspective.

  7. Using biometry to elucidate eddy flux observations of net ecosystem carbon exchange: evidence for episodic disturbance as the cause of net carbon loss from an old-growth Amazonian rainforest

    Science.gov (United States)

    Saleska, S. R.; Wofsy, S. C.; Rice, A. H.; Hutyra, L.; Pyle, E. H.; Camargo, P. B.; Portilho, K.; Marques, D. F.

    2002-12-01

    Net ecosystem exchange (NEE) of CO2, measured by eddy-covariance in a central Amazonian old-growth forest, showed ecosystem C loss of 0.5 to 2 MgC/ha/yr (see Wofsy et al invited presentation). This is in contrast to other published eddy flux studies of Amazonian C-balance most of which have reported significant uptake. In order to independently test eddy flux results, and elucidate the underlying forest vegetation dynamics driving this net loss, we surveyed trees and coarse woody debris in 20 ha of the eddy flux tower footprint (in the Tapaj¢s National Forest, km 67, near Santarém, Par , Brazil, 54d 58'W, 2d 51'S). Net flux to live wood biomass, estimated by resurvey after two years, was 1.49 +/- 0.58 Mg C/ha/yr, the net result of high growth rate (3.28 +/- 0.23 Mg C/ha/yr from a mean bole increment of 0.18 cm), recruitment of new trees (0.61 +/- 0.02 Mg C/ha/yr), and high mortality (-2.4 +/- 0.51 Mg C/ha/yr due to stem mortality of 1.8 percent/yr). The measured net gain in live wood biomass was exceeded, however, by estimated net loss (flux to CWD = -1.7 to -5.0 Mg C/ha/yr) from the large stock of CWD, resulting in an overall estimated flux to aboveground live and dead wood of -0.2 to -3.9 Mg C/ha/yr, a loss consistent with eddy flux. Three observations suggest that an episode of high mortality (possibly caused by El Ni¤o Southern Oscillation events of the 1990s) preceded study initiation and resulted in the current observations of carbon loss: (i) the stock of CWD is large, (ii) all of the net gain in live biomass is due to small-tree growth and recruitment, and (iii) the distribution of stem density was piecewise log-linear with a notable steeper slope for trees less than 40 cm DBH. This scenario confirms predictions that large variations in carbon balance may be expected in even old growth forest, and suggests that climatically-induced disturbance events may mask the relatively small effects on carbon uptake predicted from rising atmospheric carbon dioxide.

  8. The global impact factors of net primary production in different land cover types from 2005 to 2011.

    Science.gov (United States)

    Yu, Bo; Chen, Fang

    2016-01-01

    With the seriously polluted environment due to social development, the sustainability of net primary production (NPP), which is used to feed most lives on the earth, has become one of the biggest concerns that we have to consider for the sake of food shortage. There have been many researches analyzing one or two potential impact factors of NPP based on field observation data, which brings about many uncertainties for further calculation. Moreover, the frequently used process-based models heavily depend on the understandings of researchers about the NPP process. The premises of such models hinder the impact factor analysis from being objective and confident. To overcome such shortages, we collected 27 potential impact factors of global NPP in terms of eight land cover types. The feature variables include atmosphere, biosphere, anthroposphere and lithosphere parameters, which can be obtained from public available remote sensed products. The experiment shows that latitude, irradiance ultraviolet and normalized difference vegetation index are dominant factors impacting global NPP. Anthropogenic activities, precipitation and surface emissivity are influencing NPP calculation largely. However, some commonly used biosphere parameters in process-based models are actually not playing that important roles in NPP estimation. This work provides a new insight in analyzing NPP impact factors, being more objective and comprehensive compared with frequently used process-based models.

  9. Estimation of Ecosystem Parameters of the Community Land Model with DREAM: Evaluation of the Potential for Upscaling Net Ecosystem Exchange

    Science.gov (United States)

    Hendricks Franssen, H. J.; Post, H.; Vrugt, J. A.; Fox, A. M.; Baatz, R.; Kumbhar, P.; Vereecken, H.

    2015-12-01

    Estimation of net ecosystem exchange (NEE) by land surface models is strongly affected by uncertain ecosystem parameters and initial conditions. A possible approach is the estimation of plant functional type (PFT) specific parameters for sites with measurement data like NEE and application of the parameters at other sites with the same PFT and no measurements. This upscaling strategy was evaluated in this work for sites in Germany and France. Ecosystem parameters and initial conditions were estimated with NEE-time series of one year length, or a time series of only one season. The DREAM(zs) algorithm was used for the estimation of parameters and initial conditions. DREAM(zs) is not limited to Gaussian distributions and can condition to large time series of measurement data simultaneously. DREAM(zs) was used in combination with the Community Land Model (CLM) v4.5. Parameter estimates were evaluated by model predictions at the same site for an independent verification period. In addition, the parameter estimates were evaluated at other, independent sites situated >500km away with the same PFT. The main conclusions are: i) simulations with estimated parameters reproduced better the NEE measurement data in the verification periods, including the annual NEE-sum (23% improvement), annual NEE-cycle and average diurnal NEE course (error reduction by factor 1,6); ii) estimated parameters based on seasonal NEE-data outperformed estimated parameters based on yearly data; iii) in addition, those seasonal parameters were often also significantly different from their yearly equivalents; iv) estimated parameters were significantly different if initial conditions were estimated together with the parameters. We conclude that estimated PFT-specific parameters improve land surface model predictions significantly at independent verification sites and for independent verification periods so that their potential for upscaling is demonstrated. However, simulation results also indicate

  10. An organic carbon budget for coastal Southern California determined by estimates of vertical nutrient flux, net community production and export

    Science.gov (United States)

    Haskell, William Z.; Prokopenko, Maria G.; Hammond, Douglas E.; Stanley, Rachel H. R.; Berelson, William M.; Baronas, J. Jotautas; Fleming, John C.; Aluwihare, Lihini

    2016-10-01

    Organic carbon export and burial in coastal upwelling regions is an important mechanism for oceanic uptake of atmospheric CO2. In order to understand how these complex systems will respond to future climate forcing, further studies of nutrient input, biological production and export are needed. Using a 7Be-based approach, we produced an 18-month record of upwelling velocity estimates at the San Pedro Ocean Time-series (SPOT), Southern California Bight. These upwelling rates and vertical nutrient distributions have been combined to make estimates of potential new production (PNP), which are compared to estimates of net community oxygen production (NOP) made using a one-dimensional, two-box non-steady state model of euphotic zone biological oxygen supersaturation. NOP agrees within uncertainty with PNP, suggesting that upwelling is the dominant mechanism for supplying the ecosystem with new nutrients in the spring season, but negligible in the fall and winter. Combining this data set with estimates of sinking particulate organic carbon (POC) flux from water column 234Th:238U disequilibrium and sediment trap deployments, and an estimate of the ratio of dissolved organic carbon (DOC):POC consumption rates, we construct a simple box model of organic carbon in the upper 200 m of our study site. This box model (with uncertainties of ±50%) suggests that in spring, 28% of net production leaves the euphotic zone as DOC, of this, 12% as horizontal export and 16% via downward mixing. The remaining 72% of net organic carbon export exits as sinking POC, with only 10% of euphotic zone export reaching 200 m. We find the metabolic requirement for the local heterotrophic community below the euphotic zone, but above 200 m, is 105±50 mmol C m-2 d-1, or 80% of net euphotic zone production in spring.

  11. Effects of Land Use Change on Carbon Emission:A Case Study of Yuheng Mining Area

    Institute of Scientific and Technical Information of China (English)

    Yarui; WU; Wenhai; XIA

    2014-01-01

    Land use is the main factor affecting the carbon emission. Taking Yuheng Mining Area as the research object,this paper chose two periods of remote sensing data of 1999 and 2006,and adopted the remote sensing image interpretation and supervised classification to study the changes in land use types and carbon sink in different periods in the mining area. The results showed that the area of arable land was reduced from 166. 96 km2 to 81. 10 km2,the area of woodland was increased from 46.79 km2 to 134. 53 km2,and arable land decreased by 51%,but carbon sink in the mining area still showed a rising trend; the carbon sink value increased by 16. 4 million yuan in 2006 compared to 1999,an increase of 40%,indicating that the reasonable land use pattern can improve the ecological environment,and promote the sustainable development of environment and economy in the mining area.

  12. Comparing net ecosystem carbon dioxide exchange at adjacent commercial bioenergy and conventional cropping systems in Lincolnshire, United Kingdom

    Science.gov (United States)

    Morrison, Ross; Brooks, Milo; Evans, Jonathan; Finch, Jon; Rowe, Rebecca; Rylett, Daniel; McNamara, Niall

    2016-04-01

    The conversion of agricultural land to bioenergy plantations represents one option in the national and global effort to reduce greenhouse gas emissions whilst meeting future energy demand. Despite an increase in the area of (e.g. perennial) bioenergy crops in the United Kingdom and elsewhere, the biophysical and biogeochemical impacts of large scale conversion of arable and other land cover types to bioenergy cropping systems remain poorly characterised and uncertain. Here, the results of four years of eddy covariance (EC) flux measurements of net ecosystem CO2 exchange (NEE) obtained at a commercial farm in Lincolnshire, United Kingdom (UK) are reported. CO2 flux measurements are presented and compared for arable crops (winter wheat, oilseed rape, spring barely) and plantations of the perennial biofuel crops Miscanthus x. giganteus (C4) and short rotation coppice (SRC) willow (Salix sp.,C3). Ecosystem light and temperature response functions were used to analyse and compare temporal trends and spatial variations in NEE across the three land covers. All three crops were net in situ sinks for atmospheric CO2 but were characterised by large temporal and between site variability in NEE. Environmental and biological controls driving the spatial and temporal variations in CO2 exchange processes, as well as the influences of land management, will be analysed and discussed.

  13. Quantifying the effectiveness of climate change mitigation through forest plantations and carbon sequestration with an integrated land-use model.

    Science.gov (United States)

    van Minnen, Jelle G; Strengers, Bart J; Eickhout, Bas; Swart, Rob J; Leemans, Rik

    2008-04-15

    Carbon plantations are introduced in climate change policy as an option to slow the build-up of atmospheric carbon dioxide (CO2) concentrations. Here we present a methodology to evaluate the potential effectiveness of carbon plantations. The methodology explicitly considers future long-term land-use change around the world and all relevant carbon (C) fluxes, including all natural fluxes. Both issues have generally been ignored in earlier studies. Two different baseline scenarios up to 2100 indicate that uncertainties in future land-use change lead to a near 100% difference in estimates of carbon sequestration potentials. Moreover, social, economic and institutional barriers preventing carbon plantations in natural vegetation areas decrease the physical potential by 75-80% or more.Nevertheless, carbon plantations can still considerably contribute to slowing the increase in the atmospheric CO2 concentration but only in the long term. The most conservative set of assumptions lowers the increase of the atmospheric CO2 concentration in 2100 by a 27 ppm and compensates for 5-7% of the total energy-related CO2 emissions. The net sequestration up to 2020 is limited, given the short-term increased need for agricultural land in most regions and the long period needed to compensate for emissions through the establishment of the plantations. The potential is highest in the tropics, despite projections that most of the agricultural expansion will be in these regions. Plantations in high latitudes as Northern Europe and Northern Russia should only be established if the objective to sequester carbon is combined with other activities. Carbon sequestration in plantations can play an important role in mitigating the build-up of atmospheric CO2. The actual magnitude depends on natural and management factors, social barriers, and the time frame considered. In addition, there are a number of ancillary benefits for local communities and the environment. Carbon plantations are, however

  14. Quantifying the effectiveness of climate change mitigation through forest plantations and carbon sequestration with an integrated land-use model

    Directory of Open Access Journals (Sweden)

    Swart Rob J

    2008-04-01

    Full Text Available Abstract Background Carbon plantations are introduced in climate change policy as an option to slow the build-up of atmospheric carbon dioxide (CO2 concentrations. Here we present a methodology to evaluate the potential effectiveness of carbon plantations. The methodology explicitly considers future long-term land-use change around the world and all relevant carbon (C fluxes, including all natural fluxes. Both issues have generally been ignored in earlier studies. Results Two different baseline scenarios up to 2100 indicate that uncertainties in future land-use change lead to a near 100% difference in estimates of carbon sequestration potentials. Moreover, social, economic and institutional barriers preventing carbon plantations in natural vegetation areas decrease the physical potential by 75–80% or more. Nevertheless, carbon plantations can still considerably contribute to slowing the increase in the atmospheric CO2 concentration but only in the long term. The most conservative set of assumptions lowers the increase of the atmospheric CO2 concentration in 2100 by a 27 ppm and compensates for 5–7% of the total energy-related CO2 emissions. The net sequestration up to 2020 is limited, given the short-term increased need for agricultural land in most regions and the long period needed to compensate for emissions through the establishment of the plantations. The potential is highest in the tropics, despite projections that most of the agricultural expansion will be in these regions. Plantations in high latitudes as Northern Europe and Northern Russia should only be established if the objective to sequester carbon is combined with other activities. Conclusion Carbon sequestration in plantations can play an important role in mitigating the build-up of atmospheric CO2. The actual magnitude depends on natural and management factors, social barriers, and the time frame considered. In addition, there are a number of ancillary benefits for local

  15. Effects of Permafrost Thaw on Net Ecosystem Carbon Balance in a Subarctic Peatland

    Science.gov (United States)

    Wang, Z.; Roulet, N. T.; Moore, T. R.

    2014-12-01

    This research is to assess changes in net ecosystem carbon balance (NECB) with permafrost thaw in northern peatland: in particular how changes in C biogeochemistry influence NECB. Thawed transects associated with varying stages of permafrost thaw: from palsas with intact permafrost (P), through edge of palsa (EP), dry lawn (DL), wet lawn (WL), edge of thawed pond (ET), pond sedges (PS), to several thawed ponds (TP) in a subarctic peatland in northern Quebec were sampled in the snow free seasons of 2013 and 2014. The exchange of CO2 and CH4, vegetation, dissolved organic C (DOC) concentration and biodegradability, active layer depth, air and peat temperatures, water table depth (WT), pH, and conductivity were measured. Peat temperatures were quite similar among different locations, but the WT decreased significantly along the transect creating varied environmental conditions that supporting different plant communities. From dry to wet area, vegetation abundance and biomass showed reductions of shrubs and lichens, and increases of Sphagnum, grasses and sedges. Pore water pH increased from dry to wet area, and conductivity slightly decreased. Wet thaw area WL, ET and PS had relatively higher season gross ecosystem production (GEP) and higher season ecosystem respiration (ER), but relative similar net ecosystem CO2 exchange (NEE). Only TP had a significant higher positive season NEE. Palsa was the only CH4 sink, and quite high CH4 emissions were found after it thawed. CH4-C release significantly increased from dry to wet in thawed area, which even several times bigger than total C exchange in ET and PS. Generally, wet area had higher DOC concentration and higher DOC biodegradability indicated by lower SUVA254 (except PS which received great influence from pond). All components in the NECB (GEP, ER, CH4, DOC) increased significantly in magnitude from palsa to wet thawed area, and ecosystem C sink turned into source as palsa thawed into PS and TP. These results

  16. Carbon emissions from land-use change and management in China between 1990 and 2010.

    Science.gov (United States)

    Lai, Li; Huang, Xianjin; Yang, Hong; Chuai, Xiaowei; Zhang, Mei; Zhong, Taiyang; Chen, Zhigang; Chen, Yi; Wang, Xiao; Thompson, Julian R

    2016-11-01

    China has experienced enormous changes in land use in recent decades, which are largely driven by its unparalleled economic development. We analyze changes in vegetation and soil carbon storage between 1990 and 2010 resulting from combinations of land-use category conversion and management. Results demonstrate a major decline in grasslands (-6.85%; 20.83 × 10(6) ha) and large increases in urban areas (+43.73%; 6.87 × 10(6) ha), farmlands (+0.84%; 1.48 × 10(6) ha), and forests (+0.67%; 1.52 × 10(6) ha). The total soil organic carbon pool has been reduced by approximately 11.5 Tg of carbon (TgC) year(-1), whereas 13.2 TgC year(-1) has accumulated in the biomass carbon pool because of land-use category change. Large carbon losses (approximately 101.8 TgC year(-1)) have resulted from land management failures, including forest fires and insect pests. Overall land-use change and land management have contributed about 1.45 Pg of carbon to the total carbon released from 1990 to 2010. Our results highlight the importance of improving land-use management, especially in view of the recently proposed expansion of urban areas in China.

  17. Distributions of carbon in calcareous soils under different land uses in western Iran

    Directory of Open Access Journals (Sweden)

    H. Sepahvand

    2016-10-01

    Full Text Available Concentrations of Natural stable and unstable carbon in ecosystems have been used extensively to help to understand a wide range of soil processes and functions. This study was conducted to explore the effects of land use changes on different carbon fractions (F1, F2, F3 and F4, permanganate oxidizable carbon (POXC, soil organic carbon (SOC and total organic carbon (TOC associated with soils in calcareous soils of western Iran. Four popular land uses in the selected site including natural forest, range land, dryland farming and irrigated farming systems were employed as the basis of soil sampling. The results showed a strong relationship between land use conversion and SOC stocks changes. The greatest mean values for carbon content and the least mean values of CaCO3 in bulk topsoil (0–15 cm in the forest land were observed. Dryland farming had the least both active and passive pools of C in comparison with the other land uses. The positive and significant correlations was observed between SOC, Total C and POXC contents and different C fractions. Taking C and POXC pools into account, a more definitive picture of the soil C is obtained than when only total C is measured. The influence of land use changes on overall soil carbon stocks could be helpful for making management decision for farmers and policy makers in the future, for enhancing the potential of C sequestration in western Iran.

  18. Reconciling estimates of the contemporary North American carbon balance among terrestrial biosphere models, atmospheric inversions, and a new approach for estimating net ecosystem exchange from inventory-based data

    Science.gov (United States)

    Hayes, Daniel J.; Turner, David P.; Stinson, Graham; McGuire, A. David; Wei, Yaxing; West, Tristram O.; Heath, Linda S.; de Jong, Bernardus; McConkey, Brian G.; Birdsey, Richard A.; Kurz, Werner A.; Jacobson, Andrew R.; Huntzinger, Deborah N.; Pan, Yude; Post, W. Mac; Cook, Robert B.

    2012-01-01

    We develop an approach for estimating net ecosystem exchange (NEE) using inventory-based information over North America (NA) for a recent 7-year period (ca. 2000–2006). The approach notably retains information on the spatial distribution of NEE, or the vertical exchange between land and atmosphere of all non-fossil fuel sources and sinks of CO2, while accounting for lateral transfers of forest and crop products as well as their eventual emissions. The total NEE estimate of a -327 ± 252 TgC yr-1 sink for NA was driven primarily by CO2 uptake in the Forest Lands sector (-248 TgC yr-1), largely in the Northwest and Southeast regions of the US, and in the Crop Lands sector (-297 TgC yr-1), predominantly in the Midwest US states. These sinks are counteracted by the carbon source estimated for the Other Lands sector (+218 TgC yr-1), where much of the forest and crop products are assumed to be returned to the atmosphere (through livestock and human consumption). The ecosystems of Mexico are estimated to be a small net source (+18 TgC yr-1) due to land use change between 1993 and 2002. We compare these inventory-based estimates with results from a suite of terrestrial biosphere and atmospheric inversion models, where the mean continental-scale NEE estimate for each ensemble is -511 TgC yr-1 and -931 TgC yr-1, respectively. In the modeling approaches, all sectors, including Other Lands, were generally estimated to be a carbon sink, driven in part by assumed CO2 fertilization and/or lack of consideration of carbon sources from disturbances and product emissions. Additional fluxes not measured by the inventories, although highly uncertain, could add an additional -239 TgC yr-1 to the inventory-based NA sink estimate, thus suggesting some convergence with the modeling approaches.

  19. Reconciling estimates of the contemporary North American carbon balance among terrestrial biosphere models, atmospheric inversions and a new approach for estimating net ecosystem exchange from inventory-based data

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, Daniel J [ORNL; Turner, David P [Oregon State University, Corvallis; Stinson, Graham [Pacific Forestry Centre, Canadian Forest Service; Mcguire, David [University of Alaska; Wei, Yaxing [ORNL; West, Tristram O. [Joint Global Change Research Institute, PNNL; Heath, Linda S. [USDA Forest Service; De Jong, Bernardus [ECOSUR; McConkey, Brian G. [Agriculture and Agri-Food Canada; Birdsey, Richard A. [U.S. Department of Agriculture Forest Service; Kurz, Werner [Canadian Forest Service; Jacobson, Andrew [NOAA ESRL and CIRES; Huntzinger, Deborah [University of Michigan; Pan, Yude [U.S. Department of Agriculture Forest Service; Post, Wilfred M [ORNL; Cook, Robert B [ORNL

    2012-01-01

    We develop an approach for estimating net ecosystem exchange (NEE) using inventory-based information over North America (NA) for a recent 7-year period (ca. 2000 2006). The approach notably retains information on the spatial distribution of NEE, or the vertical exchange between land and atmosphere of all non-fossil fuel sources and sinks of CO2, while accounting for lateral transfers of forest and crop products as well as their eventual emissions. The total NEE estimate of a 327 252 TgC yr1 sink for NA was driven primarily by CO2 uptake in the Forest Lands sector (248 TgC yr1), largely in the Northwest and Southeast regions of the US, and in the Crop Lands sector (297 TgC yr1), predominantly in the Midwest US states. These sinks are counteracted by the carbon source estimated for the Other Lands sector (+218 TgC yr1), where much of the forest and crop products are assumed to be returned to the atmosphere (through livestock and human consumption). The ecosystems of Mexico are estimated tobe a small net source (+18 TgC yr1) due to land use change between 1993 and 2002. We compare these inventorybased estimates with results from a suite of terrestrial biosphere and atmospheric inversion models, where the mean continental-scale NEE estimate for each ensemble is 511 TgC yr1 and 931 TgC yr1, respectively. In the modeling approaches, all sectors, including Other Lands, were generally estimated to be a carbon sink, driven in part by assumed CO2 fertilization and/or lack of consideration of carbon sources from disturbances and product emissions. Additional fluxes not measured by the inventories, although highly uncertain, could add an additional 239 TgC yr1 to the inventory-based NA sink estimate, thus suggesting some convergence with the modeling approaches.

  20. Global Tree Cover and Biomass Carbon on Agricultural Land: The contribution of agroforestry to global and national carbon budgets

    Science.gov (United States)

    Zomer, Robert J.; Neufeldt, Henry; Xu, Jianchu; Ahrends, Antje; Bossio, Deborah; Trabucco, Antonio; van Noordwijk, Meine; Wang, Mingcheng

    2016-07-01

    Agroforestry systems and tree cover on agricultural land make an important contribution to climate change mitigation, but are not systematically accounted for in either global carbon budgets or national carbon accounting. This paper assesses the role of trees on agricultural land and their significance for carbon sequestration at a global level, along with recent change trends. Remote sensing data show that in 2010, 43% of all agricultural land globally had at least 10% tree cover and that this has increased by 2% over the previous ten years. Combining geographically and bioclimatically stratified Intergovernmental Panel on Climate Change (IPCC) Tier 1 default estimates of carbon storage with this tree cover analysis, we estimated 45.3 PgC on agricultural land globally, with trees contributing >75%. Between 2000 and 2010 tree cover increased by 3.7%, resulting in an increase of >2 PgC (or 4.6%) of biomass carbon. On average, globally, biomass carbon increased from 20.4 to 21.4 tC ha‑1. Regional and country-level variation in stocks and trends were mapped and tabulated globally, and for all countries. Brazil, Indonesia, China and India had the largest increases in biomass carbon stored on agricultural land, while Argentina, Myanmar, and Sierra Leone had the largest decreases.

  1. Land Use and Changes in Carbon Budget in the Brazilian Cerrado

    Science.gov (United States)

    Bustamante, M.; Potter, C.; Corbeels, M.; Scopel, E.

    2007-12-01

    Tropical savannas cover 22.5 x 106 km2, an area nearly 30% larger than the area of tropical forests. Although the average carbon \\(C\\) content of savanna vegetation is only about 25% as great as tropical forest vegetation (29 vs. 120 Mg C ha-1), land use changes in tropical savannas are even more rapid than changes in tropical forests. The Brazilian savanna, locally known as Cerrado, covers about 2 x 106 km2 and is the largest savanna formation in South America. Its area is comparable to the Miombo savanna of Southern Africa. Biomass in the Cerrado varies from 1.9 Mg C ha-1 \\(grassy campo limpo\\) to 30.5 Mg C ha-1 \\(woody cerradão\\). Cerrado vegetation can be highly productive; annual net ecosystem exchange fluxes as high as 2.5 Mg C ha-1 yr-1 have been measured although lower values are more common. Assuming approximately 40 years of land use conversion and an average net biomass change \\(29 Mg C ha-1\\), this would lead to an average loss of C from the Cerrado of nearly 0.1 Pg C y-1. These values can be higher if belowground biomass is included as in Cerrado the ratio of belowground to aboveground biomass reaches values as high as 7.7. Fire is a principle factor controlling vegetation dynamics in the Cerrado \\(especially the ratio of grass to woody biomass\\). Frequent fires kill trees and shrubs favoring grasses favoring more open vegetation types. Inversely fire suppression favors woody growth. Advances in agricultural productivity have made the Cerrado the leading region of Brazil for beef cattle production and soybean production. It is estimated that between 40% and 55% of the region has been converted to pasture and other agricultural uses with peak rates in the early 1970's. Increasing international demand of biofuels represents a new aspect of land use in the region. Soil organic matter stocks exceed biomass stocks and data on soil C storage with conversion of native savanna into pasture indicated that well-managed, cultivated pastures may provide

  2. The effect of carbon credits on savanna land management and priorities for biodiversity conservation.

    Science.gov (United States)

    Douglass, Lucinda L; Possingham, Hugh P; Carwardine, Josie; Klein, Carissa J; Roxburgh, Stephen H; Russell-Smith, Jeremy; Wilson, Kerrie A

    2011-01-01

    Carbon finance offers the potential to change land management and conservation planning priorities. We develop a novel approach to planning for improved land management to conserve biodiversity while utilizing potential revenue from carbon biosequestration. We apply our approach in northern Australia's tropical savanna, a region of global significance for biodiversity and carbon storage, both of which are threatened by current fire and grazing regimes. Our approach aims to identify priority locations for protecting species and vegetation communities by retaining existing vegetation and managing fire and grazing regimes at a minimum cost. We explore the impact of accounting for potential carbon revenue (using a carbon price of US$14 per tonne of carbon dioxide equivalent) on priority areas for conservation and the impact of explicitly protecting carbon stocks in addition to biodiversity. Our results show that improved management can potentially raise approximately US$5 per hectare per year in carbon revenue and prevent the release of 1-2 billion tonnes of carbon dioxide equivalent over approximately 90 years. This revenue could be used to reduce the costs of improved land management by three quarters or double the number of biodiversity targets achieved and meet carbon storage targets for the same cost. These results are based on generalised cost and carbon data; more comprehensive applications will rely on fine scale, site-specific data and a supportive policy environment. Our research illustrates that the duel objective of conserving biodiversity and reducing the release of greenhouse gases offers important opportunities for cost-effective land management investments.

  3. Taking climate, land use, and social economy into estimation of carbon budget in the Guanzhong-Tianshui Economic Region of China.

    Science.gov (United States)

    Li, Ting; Li, Jing; Zhou, Zixiang; Wang, Yanze; Yang, Xiaonan; Qin, Keyu; Liu, Jingya

    2017-04-01

    Carbon sequestration is an indispensable ecosystem service provided by soil and vegetation, so mapping and valuing the carbon budget by considering both ecological and social factors is an important trend in evaluating ecosystem services. In this work, we established multiple scenarios to evaluate the impacts of land use change, population growth, carbon emission per capita, and carbon markets on carbon budget. We quantified carbon sinks (aboveground and belowground) under different scenarios, using the Carnegie-Ames-Stanford Approach (CASA) model and an improved carbon cycle process model, and studied carbon sources caused by human activities by analyzing the spatial distribution of human population and carbon emission per capita. We also assessed the net present value (NPV) for carbon budgets under different carbon price and discount rate scenarios using NPV model. Our results indicate that the carbon budget of Guanzhong-Tianshui Economic Region is surplus: Carbon sinks range from 1.50 × 10(10) to 1.54 × 10(10) t, while carbon sources caused by human activities range from 2.76 × 10(5) to 7.60 × 10(5) t. And the NPV for carbon deficits range from 3.20 × 10(11) RMB to 1.52 × 10(12) RMB. From the perspective of ecological management, deforestation, urban sprawl, population growth, and excessive carbon consumption are considered as the main challenges in balancing carbon sources and sinks. Levying carbon tax would be a considerable option when decision maker develops carbon emission reduction policies. Our results provide a scientific and credible reference for harmonious and sustainable development in the Guanzhong-Tianshui Economic Region of China.

  4. Carbon lost and carbon gained: a study of vegetation and carbon trade-offs among diverse land uses in Phoenix, Arizona.

    Science.gov (United States)

    McHale, Melissa R; Hall, Sharon J; Majumdar, Anandamayee; Grimm, Nancy B

    2017-03-01

    Human modification and management of urban landscapes drastically alters vegetation and soils, thereby altering carbon (C) storage and rates of net primary productivity (NPP). Complex social and ecological processes drive vegetation cover in cities, leading to heterogeneity in C dynamics depending on regional climate, land use, and land cover. Recent work has demonstrated homogenization in ecological processes within human-dominated landscapes (the urban convergence hypothesis) in soils and biotic communities. However, a lack of information on vegetation in arid land cities has hindered an understanding of potential C storage and NPP convergence across a diversity of ecosystem types. We estimated C storage and NPP of trees and shrubs for six different land-use types in the arid metropolis of Phoenix, Arizona, USA, and compared those results to native desert ecosystems, as well as other urban and natural systems around the world. Results from Phoenix do not support the convergence hypothesis. In particular, C storage in urban trees and shrubs was 42% of that found in desert vegetation, while NPP was only 20% of the total NPP estimated for comparable natural ecosystems. Furthermore, the overall estimates of C storage and NPP associated with urban trees in the CAP ecosystem were much lower (8-63%) than the other cities included in this analysis. We also found that C storage (175.25-388.94 g/m(2) ) and NPP (8.07-15.99 g·m(-2) ·yr(-1) ) were dominated by trees in the urban residential land uses, while in the desert, shrubs were the primary source for pools (183.65 g/m(2) ) and fluxes (6.51 g·m(-2) ·yr(-1) ). These results indicate a trade-off between shrubs and trees in arid ecosystems, with shrubs playing a major role in overall C storage and NPP in deserts and trees serving as the dominant C pool in cities. Our research supports current literature that calls for the development of spatially explicit and standardized methods for analyzing C dynamics associated

  5. Modeling of Carbon Sequestration on Eucalyptus Plantation in Brazililian Cerrado Region for Better Characterization of Net Primary Productivity

    Science.gov (United States)

    Echeverri, J. D.; Siqueira, M. B.

    2013-05-01

    Managed Forests have important roles in climate change due to their contribution to CO2 sequestration stored in their biomass, soils and products therefrom. Terrestrial net primary production (NPP, kgC/m2), equal to gross primary production minus autotrophic respiration, represents the carbon available for plant allocation to leaves, stems, roots, defensive compounds, and reproduction and is the basic measure of biological productivity. Tree growth, food production, fossil fuel production, and atmospheric CO2 levels are all strongly controlled by NPP. Accurate quantification of NPP at local to global scales is therefore central topic for carbon cycle researchers, foresters, land and resource managers, and politicians. For recent or current NPP estimates, satellite remote sensing can be used but for future climate scenarios, simulation models are required. There is an increasing trend to displace natural Brazilian Cerrado to Eucalyptus for paper mills and energy conversion from biomass. The objective of this research exercise is to characterize NPP from managed Eucalyptus plantation in the Brazilian Cerrado. The models selected for this study were the 3-PG and Biome-BGC. The selection of these models aims to cover a range of complexity that allow the evaluation of the processes modeled as to its relevance to a best estimate of productivity in eucalyptus forests. 3-PG model is the simplest of the models chosen for this exercise. Its main purpose is to estimate productivity of forests in timber production. The model uses the relationship of quantum efficiency in the transformation of light energy into biomass for vegetative growth calculations in steps in time of one month. Adverse weather conditions are treated with reduction factors applied in the top efficiency. The second model is the Biome-BGC that uses biology and geochemistry principles to estimate leaf-level photosynthesis based on limiting factors such as availability of light and nutrient constraints. The

  6. The Elum Project: A Network of UK Sites to Understand Land-Use Transitions to Bioenergy and Their Implications for Greenhouse Gas Balance and Carbon Cycling

    Science.gov (United States)

    Harris, Z. M.; Alberti, G.; Bottoms, E.; Rowe, R.; Parmar, K.; Marshall, R.; Elias, D.; Smith, P.; Dondini, M.; Pogson, M.; Richards, M.; Finch, J.; Ineson, P.; Keane, B.; Perks, M.; Wilkinson, M.; Yamulki, S.; Donnison, I.; Farrar, K.; Massey, A.; McCalmont, J.; Drewer, J.; Sohi, S.; McNamara, N.; Taylor, G.

    2014-12-01

    Rising anthropogenic greenhouse gas (GHG) emissions coupled with an increasing need to address energy security are resulting in the development of cleaner, more sustainable alternatives to traditional fossil fuel sources. Bioenergy crops have been proposed to be able to mitigate the effects of climate change as well as provide increased energy security. The aim of this project is to assess the impact of land conversion to second generation non-food bioenergy crops on GHG balance for several land use transitions, including from arable, grassland and forest. A network of 6 sites was established across the UK to assess the processes underpinning GHG balance and to provide input data to a model being used to assess the sustainability of different land use transitions. Monthly analysis of soil GHGs shows that carbon dioxide contributes most to the global warming potential of these bioenergy crops, irrespective of transition. Nitrous oxide emissions were low for all crops except arable cropping and methane emissions were very low for all sites. Nearly all sites have shown a significant decrease in CO2 flux from the control land use. Eddy flux approaches, coupled with soil assessments show that for the transition from grassland to SRC willow there is a significant reduction in GHG emissions from soil and a negative net ecosystem exchange due to increased GPP and ecosystem respiration. These results suggest for this land use transition to bioenergy in a UK specific context, there may be a net benefit for ecosystem GHG exchange of transition to bioenergy Finally we are developing a meta-modelling tool to allow land use managers to make location-specific, informed decisions about land use change to bioenergy. This work is based on the Ecosystem Land Use Modelling & Soil Carbon GHG Flux Trial (ELUM) project, which was commissioned and funded by the Energy Technologies Institute (ETI). This project is co-ordinated by the Centre for Ecology & Hydrology (www.elum.ac.uk).

  7. An observational constraint on stomatal function in forests: evaluating coupled carbon and water vapor exchange with carbon isotopes in the Community Land Model (CLM4.5)

    Science.gov (United States)

    Raczka, Brett; Duarte, Henrique F.; Koven, Charles D.; Ricciuto, Daniel; Thornton, Peter E.; Lin, John C.; Bowling, David R.

    2016-09-01

    Land surface models are useful tools to quantify contemporary and future climate impact on terrestrial carbon cycle processes, provided they can be appropriately constrained and tested with observations. Stable carbon isotopes of CO2 offer the potential to improve model representation of the coupled carbon and water cycles because they are strongly influenced by stomatal function. Recently, a representation of stable carbon isotope discrimination was incorporated into the Community Land Model component of the Community Earth System Model. Here, we tested the model's capability to simulate whole-forest isotope discrimination in a subalpine conifer forest at Niwot Ridge, Colorado, USA. We distinguished between isotopic behavior in response to a decrease of δ13C within atmospheric CO2 (Suess effect) vs. photosynthetic discrimination (Δcanopy), by creating a site-customized atmospheric CO2 and δ13C of CO2 time series. We implemented a seasonally varying Vcmax model calibration that best matched site observations of net CO2 carbon exchange, latent heat exchange, and biomass. The model accurately simulated observed δ13C of needle and stem tissue, but underestimated the δ13C of bulk soil carbon by 1-2 ‰. The model overestimated the multiyear (2006-2012) average Δcanopy relative to prior data-based estimates by 2-4 ‰. The amplitude of the average seasonal cycle of Δcanopy (i.e., higher in spring/fall as compared to summer) was correctly modeled but only when using a revised, fully coupled An - gs (net assimilation rate, stomatal conductance) version of the model in contrast to the partially coupled An - gs version used in the default model. The model attributed most of the seasonal variation in discrimination to An, whereas interannual variation in simulated Δcanopy during the summer months was driven by stomatal response to vapor pressure deficit (VPD). The model simulated a 10 % increase in both photosynthetic discrimination and water-use efficiency (WUE

  8. Seasonal distribution of dissolved inorganic carbon and net community production on the Bering Sea shelf

    Directory of Open Access Journals (Sweden)

    J. T. Mathis

    2010-05-01

    Full Text Available In order to assess the current state of net community production (NCP in the southeastern Bering Sea, we measured the spatio-temporal distribution and controls on dissolved inorganic carbon (DIC concentrations in spring and summer of 2008 across six shelf domains defined by differing biogeochemical characteristics. DIC concentrations were tightly coupled to salinity in spring and ranged from ~1900 μmoles kg−1 over the inner shelf to ~2400 μmoles kg−1 in the deeper waters of the Bering Sea. In summer, DIC concentrations were lower due to dilution from sea ice melt, terrestrial inputs, and primary production. Concentrations were found to be as low ~1800 μmoles kg−1 over the inner shelf. We found that DIC concentrations were drawn down 30–150 μmoles kg−1 in the upper 30 m of the water column due to primary production and calcium carbonate formation between the spring and summer occupations. Using the seasonal drawdown of DIC, estimated rates of NCP on the inner, middle, and outer shelf averaged 28 ± 9 mmoles C m−2 d−1. However, higher rates of NCP (40–47 mmoles C m−2 d−1 were observed in the "Green Belt" where the greatest confluence of nutrient-rich basin water and iron-rich shelf water occurs. We estimated that in 2008, total NCP across the shelf was on the order of ~96 Tg C yr−1. Due to the paucity of consistent, comparable productivity data, it is impossible at this time to quantify whether the system is becoming more or less productive. However, as changing climate continues to modify the character of the Bering Sea, we have shown that NCP can be an important indicator of how the ecosystem is functioning.

  9. Profiles of carbon stocks in forest, reforestation and agricultural land, Northern Thailand

    Institute of Scientific and Technical Information of China (English)

    P. Pibumrung; N. Gajaseni; A. Popan

    2008-01-01

    A study was conducted to assess carbon stocks in various forms and land-use types and reliably estimate the impact of land use on C stocks in the Nam Yao sub-watershed (19°05'10"N, 100°37'02"E), Thailand. The carbon stocks of aboveground, soil organic and fine root within primary forest, reforestation and agricultural land were estimated through field data collection. Results revealed that the amount of total carbon stock of forests (357.62 ± 28.51 Mg·ha-1, simplified expression of Mg (carbon)·ha-1) was significantly greater (P< 0.05) than the reforestation (195.25 ±14.38 Mg·ha-1) and the agricultural land (103.10±18.24 Mg·ha-1). Soil organic carbon in the forests (196.24 ±22.81 Mg·ha-1) was also significantly greater (P< 0.05) than the reforestation (146.83± 7.22 Mg·ha-1) and the agricultural land (95.09 ± 14.18 Mg·ha-1). The differences in carbon stocks across land-use types are the primary consequence of variations in the vegetation biomass and the soil organic matter. Fine root carbon was a small fraction of carbon stocks in all land-use types. Most of the soil organic carbon and fine root carbon content was found in the upper 40-cm layer and decreased with soil depth. The aboveground carbon(soil organic carbon: fine root carbon ratios (ABGC: SOC: FRC), was 5:8:1, 2:8:1, and 3:50:1 for the forest, reforestation and agricultural land, respectively. These results indicate that a relatively large proportion of the C loss is due to forest conversion to agricultural land. However, the C can be effectively recaptured through reforestation where high levels of C are stored in biomass as carbon sinks, facilitating carbon dioxide mitigation.

  10. Effects of land use and fine-scale environmental heterogeneity on net ecosystem production over a temperate coniferous forest landscape

    Science.gov (United States)

    Turner, David P.; Guzy, Michael; Lefsky, Michael A.; van Tuyl, Steve; Sun, Osbert; Daly, Chris; Law, Beverly E.

    2003-04-01

    In temperate coniferous forests, spatial variation in net ecosystem production (NEP) is often associated with variation in stand age and heterogeneity in environmental factors such as soil depth. However, coarse spatial resolution analyses used to evaluate the terrestrial contribution to global NEP do not generally incorporate these effects. In this study, a fine-scale (25 m grid) analysis of NEP over a 164-km2 area of productive coniferous forests in the Pacific Northwest region of the United States was made to evaluate the effects of including fine scale information in landscape-scale NEP assessments. The Enhanced Thematic Mapper (ETM+) sensor resolved five cover classes in the study area and further differentiated between young, mature and old-growth conifer stands. ETM+ was also used to map current leaf area index (LAI) based on an empirical relationship of observed LAI to spectral vegetation indices. A daily time step climatology, based on 18 years of meteorological observations, was distributed (1 km resolution) over the mountainous terrain of the study area using the DAYMET model. Estimates of carbon pools and flux associated with soil, litter, coarse woody debris and live trees were then generated by running a carbon cycle model (Biome-BGC) to a state that reflected the current successional status and LAI of each grid cell, as indicated by the remote sensing observations. Estimated annual NEP for 1997 over the complete study area averaged 230 g C m-2, with most of the area acting as a carbon sink. The area-wide NEP is strongly positive because of reduced harvesting in the last decade and the recovery of areas harvested between 1940 and 1990. The average value was greater than would be indicated if the entire area was assumed to be a mature conifer stand, as in a coarse-scale analysis. The mean NEP varied interannually by over a factor of two. This variation was 38% less than the interannual variation for a single point. The integration of process models

  11. Variation and Trends of Landscape Dynamics, Land Surface Phenology and Net Primary Production of the Appalachian Mountains

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yeqiao; Zhao, Jianjun; Zhou, Yuyu; Zhang, Hongyan

    2012-12-15

    The gradients of the Appalachian Mountains in elevations and latitudes provide a unique regional perspective of landscape variations in the eastern United States and a section of the southeastern Canada. This study reveals patterns and trends of landscape dynamics, land surface phenology and ecosystem production along the Appalachian Mountains using time series data from Global Inventory Modeling and Mapping Studies (GIMMS) and AVHRR Global Production Efficiency Model (GloPEM) datasets. We analyzed the spatial and temporal patterns of Normalized Difference Vegetation Index (NDVI), length of growing season (LOS) and net primary production (NPP) of selected ecoregions along the Appalachian Mountains regions. We compared the results out of the Appalachian Mountains regions in different spatial contexts including the North America and the Appalachian Trail corridor area. To reveal latitudinal variations we analyzed data and compared the results between 30°N-40°N and 40°N-50°N latitudes. The result revealed significant decreases in annual peak NDVI in the Appalachian Mountains regions. The trend for the Appalachian Mountains regions was -0.0018 (R2=0.55, P<0.0001) NDVI unit decrease per year during 25 years between 1982 and 2006. The LOS had prolonged 0.3 day yr-1 during 25 years over the Appalachian Mountains regions. The NPP increased by 2.68 gC m-2yr-2 in Appalachian Mountains regions from 1981 to 2000. The comparison with the North America reveals the effects of topography and ecosystem compositions of the Appalachian Mountains. The comparison with the Appalachian Trail corridor area provides a regional mega-transect view of the measured variables.

  12. Economic Impact of Net Carbon Payments and Bioenergy Production in Fertilized and Non-Fertilized Loblolly Pine Plantations

    Directory of Open Access Journals (Sweden)

    Prativa Shrestha

    2015-08-01

    Full Text Available Sequestering carbon in forest stands and using woody bioenergy are two potential ways to utilize forests in mitigating emissions of greenhouse gases (GHGs. Such forestry related strategies are, however, greatly influenced by carbon and bioenergy markets. This study investigates the impact of both carbon and woody bioenergy markets on land expectation value (LEV and rotation age of loblolly pine (Pinus taeda L. forests in the southeastern United States for two scenarios—one with thinning and no fertilization and the other with thinning and fertilization. Economic analysis was conducted using a modified Hartman model. The amount of carbon dioxide (CO2 emitted during various activities such as management of stands, harvesting, and product decay was included in the model. Sensitivity analysis was conducted with a range of carbon offset, wood for bioenergy, and forest product prices. The results showed that LEV increased in both management scenarios as the price of carbon and wood for bioenergy increased. However, the results indicated that the management scenario without fertilizer was optimal at low carbon prices and the management scenario with fertilizer was optimal at higher carbon prices for medium and low forest product prices. Carbon payments had a greater impact on LEV than prices for wood utilized for bioenergy. Also, increase in the carbon price increased the optimal rotation age, whereas, wood prices for bioenergy had little impact. The management scenario without fertilizer was found to have longer optimal rotation ages.

  13. Incorporation of crop phenology in Simple Biosphere Model (SiBcrop to improve land-atmosphere carbon exchanges from croplands

    Directory of Open Access Journals (Sweden)

    E. Lokupitiya

    2009-06-01

    Full Text Available Croplands are man-made ecosystems that have high net primary productivity during the growing season of crops, thus impacting carbon and other exchanges with the atmosphere. These exchanges play a major role in nutrient cycling and climate change related issues. An accurate representation of crop phenology and physiology is important in land-atmosphere carbon models being used to predict these exchanges. To better estimate time-varying exchanges of carbon, water, and energy of croplands using the Simple Biosphere (SiB model, we developed crop-specific phenology models and coupled them to SiB. The coupled SiB-phenology model (SiBcrop replaces remotely-sensed NDVI information, on which SiB originally relied for deriving Leaf Area Index (LAI and the fraction of Photosynthetically Active Radiation (fPAR for estimating carbon dynamics. The use of the new phenology scheme within SiB substantially improved the prediction of LAI and carbon fluxes for maize, soybean, and wheat crops, as compared with the observed data at several AmeriFlux eddy covariance flux tower sites in the US mid continent region. SiBcrop better predicted the onset and end of the growing season, harvest, interannual variability associated with crop rotation, day time carbon uptake (especially for maize and day to day variability in carbon exchange. Biomass predicted by SiBcrop had good agreement with the observed biomass at field sites. In the future, we will predict fine resolution regional scale carbon and other exchanges by coupling SiBcrop with RAMS (the Regional Atmospheric Modeling System.

  14. Carbon sequestration in the soils of aquaculture ponds, crop land, and forest land in southern Ohio, USA.

    Science.gov (United States)

    Adhikari, Subhendu; Lal, Rattan; Wang, Han-Ping

    2014-03-01

    Soil samples were collected from four aquaculture ponds (yellow perch culture), a control pond (without aquaculture activities, fallow pond), crop land (under corn), and forest land to estimate the carbon (C) sequestration potential in the Piketon county, Ohio, USA. The averaged total of C was 6.5 ± 2, 8.8 ± 2, 8.53 ± 0.2 and 10.49 ± 1.1 Mg/ha (Mg=10(6)g) in  2.5mm), for aquaculture ponds, control ponds, cropland and forest land, respectively. The soil/sediment C pool followed the order of forest > crop land soils > aquaculture pond soils.

  15. Modelling the impact of soil Carbonic Anhydrase on the net ecosystem exchange of OCS at Harvard forest using the MuSICA model

    Science.gov (United States)

    Launois, Thomas; Ogée, Jérôme; Commane, Roisin; Wehr, Rchard; Meredith, Laura; Munger, Bill; Nelson, David; Saleska, Scott; Wofsy, Steve; Zahniser, Mark; Wingate, Lisa

    2016-04-01

    The exchange of CO2 between the terrestrial biosphere and the atmosphere is driven by photosynthetic uptake and respiratory loss, two fluxes currently estimated with considerable uncertainty at large scales. Model predictions indicate that these biosphere fluxes will be modified in the future as CO2 concentrations and temperatures increase; however, it still unclear to what extent. To address this challenge there is a need for better constraints on land surface model parameterisations. Additional atmospheric tracers of large-scale CO2 fluxes have been identified as potential candidates for this task. In particular carbonyl sulphide (OCS) has been proposed as a complementary tracer of gross photosynthesis over land, since OCS uptake by plants is dominated by carbonic anhydrase (CA) activity, an enzyme abundant in leaves that catalyses CO2 hydration during photosynthesis. However, although the mass budget at the ecosystem is dominated by the flux of OCS into leaves, some OCS is also exchanged between the atmosphere and the soil and this component of the budget requires constraining. In this study, we adapted the process-based isotope-enabled model MuSICA (Multi-layer Simulator of the Interactions between a vegetation Canopy and the Atmosphere) to include the transport, reaction, diffusion and production of OCS within a forested ecosystem. This model was combined with 3 years (2011-2013) of in situ measurements of OCS atmospheric concentration profiles and fluxes at the Harvard Forest (Massachussets, USA) to test hypotheses on the mechanisms responsible for CA-driven uptake by leaves and soils as well as possible OCS emissions during litter decomposition. Model simulations over the three years captured well the impact of diurnally and seasonally varying environmental conditions on the net ecosystem OCS flux. A sensitivity analysis on soil CA activity and soil OCS emission rates was also performed to quantify their impact on the vertical profiles of OCS inside the

  16. Changes in organic carbon stocks upon land use conversion in the Brazilian Cerrado: A review. Agriculture

    NARCIS (Netherlands)

    Batlle-Bayer, L.; Batjes, N.H.; Bindraban, P.S.

    2010-01-01

    This paper reviews current knowledge on changes in carbon stocks upon land use conversion in the Brazilian Cerrado. First, we briefly characterize the savanna ecosystem and summarize the main published data on C stocks under natural conditions. The effects of increased land use pressure in the Cerra

  17. PALADYN v1.0, a comprehensive land surface-vegetation-carbon cycle model of intermediate complexity

    Science.gov (United States)

    Willeit, Matteo; Ganopolski, Andrey

    2016-10-01

    PALADYN is presented; it is a new comprehensive and computationally efficient land surface-vegetation-carbon cycle model designed to be used in Earth system models of intermediate complexity for long-term simulations and paleoclimate studies. The model treats in a consistent manner the interaction between atmosphere, terrestrial vegetation and soil through the fluxes of energy, water and carbon. Energy, water and carbon are conserved. PALADYN explicitly treats permafrost, both in physical processes and as an important carbon pool. It distinguishes nine surface types: five different vegetation types, bare soil, land ice, lake and ocean shelf. Including the ocean shelf allows the treatment of continuous changes in sea level and shelf area associated with glacial cycles. Over each surface type, the model solves the surface energy balance and computes the fluxes of sensible, latent and ground heat and upward shortwave and longwave radiation. The model includes a single snow layer. Vegetation and bare soil share a single soil column. The soil is vertically discretized into five layers where prognostic equations for temperature, water and carbon are consistently solved. Phase changes of water in the soil are explicitly considered. A surface hydrology module computes precipitation interception by vegetation, surface runoff and soil infiltration. The soil water equation is based on Darcy's law. Given soil water content, the wetland fraction is computed based on a topographic index. The temperature profile is also computed in the upper part of ice sheets and in the ocean shelf soil. Photosynthesis is computed using a light use efficiency model. Carbon assimilation by vegetation is coupled to the transpiration of water through stomatal conductance. PALADYN includes a dynamic vegetation module with five plant functional types competing for the grid cell share with their respective net primary productivity. PALADYN distinguishes between mineral soil carbon, peat carbon, buried

  18. A case study of carbon fluxes from land change in the southwest Brazilian Amazon

    Science.gov (United States)

    Barrett, K.; Rogan, J.; Eastman, J.R.

    2009-01-01

    Worldwide, land change is responsible for one-fifth of anthropogenic carbon emissions. In Brazil, three-quarters of carbon emissions originate from land change. This study represents a municipal-scale study of carbon fluxes from vegetation in Rio Branco, Brazil. Land-cover maps of pasture, forest, and secondary growth from 1993, 1996, 1999, and 2003 were produced using an unsupervised classification method (overall accuracy = 89%). Carbon fluxes from land change over the decade of imagery were estimated from transitions between land-cover categories for each time interval. This article presents new methods for estimating emissions reductions from carbon stored in the vegetation that replaces forests (e.g., pasture) and sequestration by new (>10-15 years) forests, which reduced gross emissions by 16, 15, and 22% for the period of 1993-1996, 1996-1999, and 1999-2003, respectively. The methods used in the analysis are broadly applicable and provide a comprehensive characterization of regional-scale carbon fluxes from land change.

  19. Hydraulic redistribution of soil water by roots affects whole-stand evapotranspiration and net ecosystem carbon exchange.

    Science.gov (United States)

    Domec, Jean-Christophe; King, John S; Noormets, Asko; Treasure, Emrys; Gavazzi, Michael J; Sun, Ge; McNulty, Steven G

    2010-07-01

    *Hydraulic redistribution (HR) of water via roots from moist to drier portions of the soil occurs in many ecosystems, potentially influencing both water use and carbon assimilation. *By measuring soil water content, sap flow and eddy covariance, we investigated the temporal variability of HR in a loblolly pine (Pinus taeda) plantation during months of normal and below-normal precipitation, and examined its effects on tree transpiration, ecosystem water use and carbon exchange. *The occurrence of HR was explained by courses of reverse flow through roots. As the drought progressed, HR maintained soil moisture above 0.15 cm(3) cm(-3) and increased transpiration by 30-50%. HR accounted for 15-25% of measured total site water depletion seasonally, peaking at 1.05 mm d(-1). The understory species depended on water redistributed by the deep-rooted overstory pine trees for their early summer water supply. Modeling carbon flux showed that in the absence of HR, gross ecosystem productivity and net ecosystem exchange could be reduced by 750 and 400 g C m(-2) yr(-1), respectively. *Hydraulic redistribution mitigated the effects of soil drying on understory and stand evapotranspiration and had important implications for net primary productivity by maintaining this whole ecosystem as a carbon sink.

  20. Global land carbon sink response to temperature and precipitation varies with ENSO phase

    Science.gov (United States)

    Fang, Yuanyuan; Michalak, Anna M.; Schwalm, Christopher R.; Huntzinger, Deborah N.; Berry, Joseph A.; Ciais, Philippe; Piao, Shilong; Poulter, Benjamin; Fisher, Joshua B.; Cook, Robert B.; Hayes, Daniel; Huang, Maoyi; Ito, Akihiko; Jain, Atul; Lei, Huimin; Lu, Chaoqun; Mao, Jiafu; Parazoo, Nicholas C.; Peng, Shushi; Ricciuto, Daniel M.; Shi, Xiaoying; Tao, Bo; Tian, Hanqin; Wang, Weile; Wei, Yaxing; Yang, Jia

    2017-06-01

    Climate variability associated with the El Niño-Southern Oscillation (ENSO) and its consequent impacts on land carbon sink interannual variability have been used as a basis for investigating carbon cycle responses to climate variability more broadly, and to inform the sensitivity of the tropical carbon budget to climate change. Past studies have presented opposing views about whether temperature or precipitation is the primary factor driving the response of the land carbon sink to ENSO. Here, we show that the dominant driver varies with ENSO phase. Whereas tropical temperature explains sink dynamics following El Niño conditions (r TG,P = 0.59, p biosphere models captures these ENSO-phase-dependent responses, highlighting a key uncertainty in modeling climate impacts on the future of the global land carbon sink.

  1. Land use changes and their relations with carbon cycles over the past 300 a in China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Land use and land cover in China have changed greatly during the past 300 a, indicated by the rapid abrupt decrease of forest land area and the rapid increase of cropland area, which can affect terrestrial carbon cycle greatly. The first-hand materials are used to analyze main characteristics for land use and land cover changes in China during the study period. The following conclusions can be drawn from this study. The cropland area in China kept increasing from 60.78×106 hm2 in 1661 to 96.09×106 hm2 in 1998. Correspondingly, the forest land area decreased from 248.13×106 hm2 in 1700 to 109.01×106 hm2 in 1949. Affected by such changes, the terrestrial ecosystem carbon storage decreased in the mean time. Car-bon lost from land use and land cover changes mainly consist of the loss from vegetation biomass and soil. In the past 300 a, about 3.70 PgC was lost from vegetation biomass, and emissions from soil ranged from 0.80 to 5.84 PgC. The moderate evaluation of soil losses was 2.48 PgC. The total loss from vegetation and soil was between 4.50 and 9.54 PgC. The moderate and optimum evaluation was 6.18 PgC. Such carbon losses distribution varied spatially from region to region. Carbon lost more significantly in Northeast China and Southwest China than in other regions, because losses of forest land in these two regions were far greater than in the other regions during the past 300 a. And losses of carbon in the other regions were also definite, such as Inner Mongolia, the western part of South China, the Xinjiang Uygur Autonomous Region, and the Qinghai-Tibet Plateau. But the carbon lost very little from the traditional agricultural regions in China, such as North China and East China. Studies on the relationship between land use and land cover change and carbon cycle in China show that the land use activities, especially those related to agriculture and forest management, began to affect terrestrial carbon storage positively in recent years.

  2. Modeling Water and Carbon Budgets in Current and Future Agricultural Land Use

    Science.gov (United States)

    Drewniak, B.; Song, J.; Prell, J.; Kotamarthi, R.; Jacob, R.

    2008-12-01

    Biofuels are a key component of renewable energy mix proposed as a substitute to fossil fuels. Biofuels are suggested as both economical and having potential for reducing atmospheric emissions of carbon from the transportation sector, by building up soil carbon levels when planted on lands where these levels have been reduced by intensive tillage. The purpose of this research is to develop a carbon-nitrogen based crop module (CNC) for the community land model (CLM) and to improve the characterization of the below and above ground carbon sequestration for bioenergy crops. The CNC simulates planting, growing, maturing and harvesting stages for three major crops: maize, soybean and wheat. In addition, dynamic root module is implemented to simulate fine root distribution and development based on relative availability of soil water and nitrogen in the root zone. Coupled CLM-CNC models is used to study crop yields, geographic locations for bioenergy crop production and soil carbon changes. Bioenergy crop cultivation is based on current crop cultivation and future land use change dataset. Soil carbon change has been simulated based on carbon input to the soil from the leaf, stem and root, and carbon emission from soil carbon decomposition. Simulated water and carbon fluxes have been compared with field observations and soil carbon content has been examined under different harvest practices.

  3. Research Needs for Carbon Management in Agriculture, Forestry and Other Land Uses

    Science.gov (United States)

    Negra, C.; Lovejoy, T.; Ojima, D. S.; Ashton, R.; Havemann, T.; Eaton, J.

    2009-12-01

    Improved management of terrestrial carbon in agriculture, forestry, and other land use sectors is a necessary part of climate change mitigation. It is likely that governments will agree in Copenhagen in December 2009 to incentives for improved management of some forms of terrestrial carbon, including maintaining existing terrestrial carbon (e.g., avoiding deforestation) and creating new terrestrial carbon (e.g., afforestation, soil management). To translate incentives into changes in land management and terrestrial carbon stocks, a robust technical and scientific information base is required. All terrestrial carbon pools (and other greenhouse gases from the terrestrial system) that interact with the atmosphere at timescales less than centuries, and all land uses, have documented mitigation potential, however, most activity has focused on above-ground forest biomass. Despite research advances in understanding emissions reduction and sequestration associated with different land management techniques, there has not yet been broad-scale implementation of land-based mitigation activity in croplands, peatlands, grasslands and other land uses. To maximize long-term global terrestrial carbon volumes, further development of relevant data, methodologies and technologies are needed to complement policy and financial incentives. The Terrestrial Carbon Group, in partnership with UN-REDD agencies, the World Bank and CGIAR institutions, is reviewing literature, convening leading experts and surveying key research institutions to develop a Roadmap for Terrestrial Carbon: Research Needs for Implementation of Carbon Management in Agriculture, Forestry and Other Land Uses. This work will summarize the existing knowledge base for emissions reductions and sequestration through land management as well as the current availability of tools and methods for measurement and monitoring of terrestrial carbon. Preliminary findings indicate a number of areas for future work. Enhanced information

  4. Integrated carbon analysis of biomass production on fallow agricultural land and product substitution in Sweden - Preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Dornburg, Veronika; Eggers, Thies; Gustavsson, Leif [Mid Sweden Univ., Oestersund (Sweden). Ecotechnology

    2006-07-15

    An important option in the Swedish context to reduce its net emissions of carbon dioxide (CO{sub 2}) is the increased use of biomass for energy and material substitution. On fallow agricultural land additional production of biomass would be possible. We analyse biomass production systems based on Norway spruce, hybrid poplar and willow hybrids and the use of this biomass to replace fossil energy and energy intensive material systems. The highest biomass production potential is for willow in southern Sweden. Fertilisation management of spruce could shorten the rotation lengths by about 17%. The fertilised production of Norway spruce with use of harvested timber for construction and use of remaining woody biomass for heat and power production gives the largest reductions of carbon emissions per hectare under the assumptions made. The use of willow for heat and power and of fertilised spruce for a wood product mix lead to the highest fossil primary energy savings in our scenarios. Spruce cultivations can achieve considerable carbon emission reductions in the long term, but willow and poplar might be a good option when fossil energy savings and carbon emission reductions should be achieved in the short term.

  5. Water and energy link in the cities of the future - achieving net zero carbon and pollution emissions footprint.

    Science.gov (United States)

    Novotny, V

    2011-01-01

    This article discusses the link between water conservation, reclamation, reuse and energy use as related to the goal of achieving the net zero carbon emission footprint in future sustainable cities. It defines sustainable ecocities and outlines quantitatively steps towards the reduction of energy use due to water and used water flows, management and limits in linear and closed loop water/stormwater/wastewater management systems. The three phase water energy nexus diagram may have a minimum inflection point beyond which reduction of water demand may not result in a reduction of energy and carbon emissions. Hence, water conservation is the best alternative solution to water shortages and minimizing the carbon footprint. A marginal water/energy chart is developed and proposed to assist planners in developing future ecocities and retrofitting older communities to achieve sustainability.

  6. Effects of rodent-induced land degradation on ecosytem carbon fluxes in alpine meadow in the Qinghai-Tibet Plateau, China

    Science.gov (United States)

    Peng, F.; Quangang, Y.; Xue, X.; Guo, J.; Wang, T.

    2014-10-01

    Land degradation induced by rodent activities is extensively occurred in alpine meadow ecosystem in the Qinghai-Tibet Plateau that would affect the ecosystem carbon (C) balance. We conducted a field experiment with six levels of land degradation (D1-D6, degradation aggravates from D1 to D6) to investigate the effects of land degradation on ecosystem C fluxes. Soil respiration (Rs), net ecosystem exchange (NEE), ecosystem respiration (ER) and gross ecosystem production (GEP) were measured from June to September 2012. Soil respiration, ER, GEP and above-ground biomass (AGB) was significantly higher in slightly degraded (D3 and D6) than in severely degraded land (D1, D2, D4 and D5). Positive averages of NEE in the growing season indicate that alpine meadow ecosystem is a weak C sink during the growing season. Net ecosystem exchange had no significant difference among different degraded levels, but the average NEE in slightly degraded group was 33.6% higher than in severely degraded group. Soil respiration, ER and NEE were positively correlated with AGB whereas soil organic C, labile soil C, total nitrogen (N) and inorganic nitrogen were associated with root biomass (RB). Our results highlight the decline of vegetation C storage of alpine meadow ecosystem with increasing number of rodent holes and suggest the control of AGB on ecosystem C fluxes, and the control of RB on soil C and N with development of land degradation.

  7. Effects of rodent-induced land degradation on ecosytem carbon fluxes in alpine meadow in the Qinghai–Tibet Plateau, China

    Directory of Open Access Journals (Sweden)

    F. Peng

    2014-10-01

    Full Text Available Land degradation induced by rodent activities is extensively occurred in alpine meadow ecosystem in the Qinghai–Tibet Plateau that would affect the ecosystem carbon (C balance. We conducted a field experiment with six levels of land degradation (D1–D6, degradation aggravates from D1 to D6 to investigate the effects of land degradation on ecosystem C fluxes. Soil respiration (Rs, net ecosystem exchange (NEE, ecosystem respiration (ER and gross ecosystem production (GEP were measured from June to September 2012. Soil respiration, ER, GEP and above-ground biomass (AGB was significantly higher in slightly degraded (D3 and D6 than in severely degraded land (D1, D2, D4 and D5. Positive averages of NEE in the growing season indicate that alpine meadow ecosystem is a weak C sink during the growing season. Net ecosystem exchange had no significant difference among different degraded levels, but the average NEE in slightly degraded group was 33.6% higher than in severely degraded group. Soil respiration, ER and NEE were positively correlated with AGB whereas soil organic C, labile soil C, total nitrogen (N and inorganic nitrogen were associated with root biomass (RB. Our results highlight the decline of vegetation C storage of alpine meadow ecosystem with increasing number of rodent holes and suggest the control of AGB on ecosystem C fluxes, and the control of RB on soil C and N with development of land degradation.

  8. Seasonal effects of irrigation on land-atmosphere latent heat, sensible heat and carbon fluxes in semi-arid basin

    Science.gov (United States)

    Xie, Zhenghui; Zeng, Yujin

    2017-04-01

    Irrigation, which constitutes 70% of the total amount of fresh water consumed by the human population, is significantly impacting the land-atmosphere fluxes. In this study, using the improved Community Land Model version 4.5 (CLM 4.5) with an active crop model, two high resolution ( 1 km) simulations investigating the effects of irrigation on Latent Heat (LH), Sensible Heat (SH) and Carbon Fluxes (or net ecosystem exchange, NEE) from land to atmosphere on the Heihe River Basin in northwestern China were conducted using a high-quality irrigation dataset compiled from 1981 to 2013. The model output and measurements from remote sensing demonstrated the capacity and viability of the developed models to reproduce ecological and hydrological processes. The results revealed the effects of irrigation on LH and SH are strongest during summer with a LH increase of 100 W/m2 and a SH decrease of 60 W/m2 over intensely irrigated areas. However, the reactions are much weaker during spring and autumn when there is much less irrigation. When the irrigation rate below 5 mm/day, the LH generally increases, whereas the SH decreases with growing irrigation rates. However, when the irrigation threshold is in excess of 5 mm/day, there is no accrued effect of irrigation on the LH and SH. Irrigation produces opposite effects to the NEE during spring and summer. During the spring, irrigation yields more discharged carbon from the land to the atmosphere, increasing the NEE value by 0.4-0.8 gC/m2/day, while the summer irrigation favors crop fixing of carbon from atmospheric CO2, decreasing the NEE value by 0.8 gC/m2/day. The repercussions of irrigation on land-atmosphere fluxes are not solely linked to the irrigation amount, and other parameters (especially the temperature) also control the effects of irrigation on LH, SH and NEE. The study indicates that how a land surface model with high spatial resolution can represent crop growing and its effects over basin scale.

  9. Natural land carbon dioxide exchanges in the ECMWF integrated forecasting system: Implementation and offline validation

    NARCIS (Netherlands)

    Boussetta, S.; Balsamo, G.; Beljaars, A.C.M.; Panareda, A.A.; Calvet, J.C.; Jacobs, C.M.J.; Hurk, van den B.J.J.M.; Viterbo, P.; Lafont, S.; Dutra, E.

    2013-01-01

    The European Centre for Medium-Range Weather Forecasts land surface model has been extended to include a carbon dioxide module. This relates photosynthesis to radiation, atmospheric carbon dioxide (CO2) concentration, soil moisture, and temperature. Furthermore, it has the option of deriving a

  10. Exploring under-utilised low carbon land resources from multiple perspectives : Case studies on regencies in Kalimantan

    NARCIS (Netherlands)

    Goh, Chun Sheng; Wicke, Birka; Potter, Lesley; Faaij, André; Zoomers, Annelies; Junginger, Martin

    2017-01-01

    Mobilising under-utilised low carbon (ULC) land resources for future agricultural production can help reducing pressure on high carbon stock land from agricultural expansion, particularly for deforestation hotspots like Kalimantan. However, the potential of ULC land is not yet well understood,

  11. Modeling Soil Organic Carbon for Agricultural Land Use Under Various Management Practices

    Science.gov (United States)

    Kotamarthi, V. R.; Drewniak, B.; Song, J.; Prell, J.; Jacob, R. L.

    2009-12-01

    Bioenergy is generating tremendous interest as an alternative energy source that is both environmentally friendly and economically competitive. The amount of land designated for agriculture is expected to expand, including changes in the current distribution of crops, as demand for biofuels increases as a carbon neutral alternative fuel source. However, the influence of agriculture on the carbon cycle is complex, and varies depending on land use change and management practices. The purpose of this research is to integrate agriculture in the carbon-nitrogen based Community Land Model (CLM) to evaluate the above and below ground carbon storage for corn, soybean, and wheat crop lands. The new model, CLM-Crop simulates carbon allocation during four growth stages, a soybean nitrogen fixation scheme, fertilizer, and harvest practices. We present results from this model simulation, which includes the impact of a new dynamic roots module to simulate the changing root structure and depth with growing season based on the availability of water and nitrogen in the root zone and a retranslocation scheme to simulate redistribution of nitrogen from leaves, roots, and stems to grain during organ development for crop yields, leaf area index (LAI), carbon allocation, and changes in soil carbon budgets under various practices such as fertilizer and residue management. Simulated crop yields for corn, soybean and wheat are in general agreement with measurements. Initial model results indicate a loss of soil organic carbon over cultivated lands after removal of natural vegetation which continues in the following years. Soil carbon in crop lands is a strong function of the residue management and has the potential to impact crop yields significantly.

  12. Assessment of Land and Water Resource Implications of the UK 2050 Carbon Plan

    Science.gov (United States)

    Konadu, D. D.; Sobral Mourao, Z.; Skelton, S.; Lupton, R.

    2015-12-01

    The UK Carbon Plan presents four low-carbon energy system pathways that achieves 80% GHG emission targets by 2050, stipulated in the UK Climate Change Act (2008). However, some of the energy technologies prescribed under these pathways are land and water intensive; but would the increase demand for land and water under these pathways lead to increased competition and stress on agricultural land, and water resources in the UK? To answer the above question, this study uses an integrated modelling approach, ForeseerTM, which characterises the interdependencies and evaluates the land and water requirement for the pathways, based on scenarios of power plant location, and the energy crop yield projections. The outcome is compared with sustainable limits of resource appropriation to assess potential stresses and competition for water and land by other sectors of the economy. The results show the Carbon Plan pathways have low overall impacts on UK water resources, but agricultural land use and food production could be significantly impacted. The impact on agricultural land use is shown to be mainly driven by projections for transport decarbonisation via indigenously sourced biofuels. On the other hand, the impact on water resources is mainly associated with increased inland thermal electricity generation capacity, which would compete with other industrial and public water demands. The results highlight the need for a critical appraisal of UK's long term low-carbon energy system planning, in particular bioenergy sourcing strategy, and the siting of thermal power generation in order to avert potential resource stress and competition.

  13. THE POTENTIAL OF RECLAIMED LANDS TO SEQUESTER CARBON AND MITIGATE THE GREENHOUSE EFFECT

    Energy Technology Data Exchange (ETDEWEB)

    Terry Brown; Song Jin

    2006-05-01

    Reclaimed mine lands have the potential to sequester carbon. The use of amendments to increase fertility and overall soil quality is encouraging. Waste amendments such as sewage sludge and clarifier sludge, as well as commercial compost were tested to determine their effects on carbon sequestration and humic acid formation in reclaimed mine lands. Sewage sludge and clarifier sludge have the potential to work as reclaimed mine lands amendments. C:N ratios need to be understood to determine probability of nutrient leaching and water contamination. Microbial activity on the humic acid fraction of sludge is directed toward the readily degradable constituents containing single chain functional groups. This finding indicate that amendments with lower molecular constituents such as aliphatic compounds are more amenable to microbial degradation, therefore serves as better nutrient sources to enhance the formation of vegetation in mine lands and leads to more efficient carbon sequestration.

  14. Land Cover Land Use Change and Soil Organic Carbon under Climate Variability in the Semi-Arid West African Sahel (1960-2050)

    Science.gov (United States)

    Dieye, Amadou M.

    2016-01-01

    Land Cover Land Use (LCLU) change affects land surface processes recognized to influence climate change at local, national and global levels. Soil organic carbon is a key component for the functioning of agro-ecosystems and has a direct effect on the physical, chemical and biological characteristics of the soil. The capacity to model and project…

  15. Land Cover Land Use Change and Soil Organic Carbon under Climate Variability in the Semi-Arid West African Sahel (1960-2050)

    Science.gov (United States)

    Dieye, Amadou M.

    2016-01-01

    Land Cover Land Use (LCLU) change affects land surface processes recognized to influence climate change at local, national and global levels. Soil organic carbon is a key component for the functioning of agro-ecosystems and has a direct effect on the physical, chemical and biological characteristics of the soil. The capacity to model and project…

  16. Carbon fluxes resulting from land-use changes in the Tamaulipan thornscrub of northeastern Mexico

    Directory of Open Access Journals (Sweden)

    Návar-Chaidez Jose

    2008-09-01

    Full Text Available Abstract Information on carbon stock and flux resulting from land-use changes in subtropical, semi-arid ecosystems are important to understand global carbon flux, yet little data is available. In the Tamaulipan thornscrub forests of northeastern Mexico, biomass components of standing vegetation were estimated from 56 quadrats (200 m2 each. Regional land-use changes and present forest cover, as well as estimates of soil organic carbon from chronosequences, were used to predict carbon stocks and fluxes in this ecosystem. For the period of 1980–1996, the Tamaulipan thornscrub is presenting an annual deforestation rate of 2.27% indicating that approximately 600 km2 of this plant community are lost every year and that 60% of the original Mexican Tamaulipan thornscrub vegetation has been lost since the 1950's. On the other hand, intensive agriculture, including introduced grasslands increased (4,000 km2 from 32 to 42% of the total studied area, largely at the expense of the Tamaulipan thornscrub forests. Land-use changes from Tamaulipan thornscrub forest to agriculture contribute 2.2 Tg to current annual carbon emissions and standing biomass averages 0.24 ± 0.06 Tg, root biomass averages 0.17 ± 0.03 Tg, and soil organic carbon averages 1.80 ± 0.27 Tg. Land-use changes from 1950 to 2000 accounted for Carbon emissions of the order of 180.1 Tg. Projected land-use changes will likely contribute to an additional carbon flux of 98.0 Tg by the year 2100. Practices to conserve sequester, and transfer carbon stocks in semi-arid ecosystems are discussed as a means to reduce carbon flux from deforestation practices.

  17. Carbon fluxes resulting from land-use changes in the Tamaulipan thornscrub of northeastern Mexico.

    Science.gov (United States)

    Návar-Chaidez, Jose de Jesus

    2008-09-30

    Information on carbon stock and flux resulting from land-use changes in subtropical, semi-arid ecosystems are important to understand global carbon flux, yet little data is available. In the Tamaulipan thornscrub forests of northeastern Mexico, biomass components of standing vegetation were estimated from 56 quadrats (200 m2 each). Regional land-use changes and present forest cover, as well as estimates of soil organic carbon from chronosequences, were used to predict carbon stocks and fluxes in this ecosystem.For the period of 1980-1996, the Tamaulipan thornscrub is presenting an annual deforestation rate of 2.27% indicating that approximately 600 km2 of this plant community are lost every year and that 60% of the original Mexican Tamaulipan thornscrub vegetation has been lost since the 1950's. On the other hand, intensive agriculture, including introduced grasslands increased (4,000 km2) from 32 to 42% of the total studied area, largely at the expense of the Tamaulipan thornscrub forests. Land-use changes from Tamaulipan thornscrub forest to agriculture contribute 2.2 Tg to current annual carbon emissions and standing biomass averages 0.24 +/- 0.06 Tg, root biomass averages 0.17 +/- 0.03 Tg, and soil organic carbon averages 1.80 +/- 0.27 Tg. Land-use changes from 1950 to 2000 accounted for Carbon emissions of the order of 180.1 Tg. Projected land-use changes will likely contribute to an additional carbon flux of 98.0 Tg by the year 2100. Practices to conserve sequester, and transfer carbon stocks in semi-arid ecosystems are discussed as a means to reduce carbon flux from deforestation practices.

  18. Rights to Land, Forests and Carbon in REDD+: Insights from Mexico, Brazil and Costa Rica

    Directory of Open Access Journals (Sweden)

    Pablo Pacheco

    2011-03-01

    Full Text Available Land tenure and carbon rights constitute critical issues to take into account in achieving emission reductions, ensuring transparent benefit sharing and determining non-permanence (or non-compliance liabilities in the context of REDD+ strategies and projects. This is so because tenure systems influence who becomes involved in efforts to avoid deforestation and improve forest management, and that land tenure, carbon rights and liabilities may be linked or divorced with implications for rural development. This paper explores these issues by looking at tenure regimes and carbon rights issues in Mexico, Brazil and Costa Rica. It is effectively shown that complex bundles of rights over forest resources have distinct implications for REDD+ design and implementation, and that REDD+ strategies in selected countries have to date failed in procedurally addressing land-use conflicts and carbon rights entitlements and liabilities.

  19. Land use change and carbon cycle in arid and semi-arid lands of East and Central Asia

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Dramatic changes in land use have occurred in arid and semi-arid landsof Asia during the 20th century. Grassland conversion into croplands and ecosystem degradation is widespread due to the high growth rate of human population and political reforms of pastoral systems. Rangeland degradation made many parts of this region vulnerable to environmental and political changes. The collapse of the livestock sector in some states of central Asia, expansion of livestock inChina and intensive degradation of grasslands in China are examples of the responses of pastoral systems to these changes over the past decades. Carbon dynamics in this region is highly variable in space and time. Land use/cover changes with widespread reduction of forest and grasslands increased carbon emission from the region.

  20. Effects of seasonal drought on net carbon dioxide exchange from a woody-plant-encroached semiarid grassland

    Science.gov (United States)

    Scott, Russell L.; Jenerette, G. Darrel; Potts, Daniel L.; Huxman, Travis E.

    2009-12-01

    Annual precipitation in the central and southern warm-desert region of North America is distributed climatologically between summer and winter periods with two prominent dry periods between them. We used energy and carbon dioxide (CO2) fluxes from eddy covariance along with standard meteorological and soil moisture measurements at a semiarid savanna in southern Arizona, United States, to better understand the consequences of warm or cool season drought on ecosystem CO2 exchange in these bimodally forced water-limited regions. Over the last 100 years, this historic grassland has converted to a savanna by the encroachment of the native mesquite tree (Prosopis velutina Woot.). During each of the 4 years of observation (2004-2007), annual precipitation (P) was below average, but monsoon (July-September) P was both above and below average while cool-season (December-March) P was always less than average by varying degrees. The ecosystem was a net source of CO2 to the atmosphere, ranging from 14 to 95 g C m-2 yr-1 with the strength of the source increasing with decreasing precipitation. When the rainfall was closest to the long-term average in its distribution and amount, the ecosystem was essentially carbon neutral. Summer drought resulted in increased carbon losses due mainly to a shortening of the growing season and the length of time later in the season when photosynthetic gain exceeds respiration loss. Severe cool season drought led to decreased spring carbon uptake and seemingly enhanced summer respiration, resulting in conditions that led to the greatest annual net carbon loss.

  1. Carbon emission reductions by substitution of improved cookstoves and cattle mosquito nets in a forest-dependent community

    Directory of Open Access Journals (Sweden)

    Somanta Chan

    2015-07-01

    Substitution of conventional cookstoves with improved cookstoves and the use of mosquito nets instead of fuelwood burning could result in using less fuelwood for the same amount of energy needed and thereby result in reduction of carbon emissions and deforestation. To realize this substitution, approximately US$ 15–25 MgCO2−1 is needed depending on discount rates and amounts of emission reduction. Substitution of cookstoves will have direct impacts on the livelihoods of forest-dependent communities and on forest protection. Financial incentives under voluntary and mandatory schemes are needed to materialize this substitution.

  2. Interannual variability of net ecosystem productivity in forests is explained by carbon flux phenology in autumn

    DEFF Research Database (Denmark)

    Wu, Chaoyang; Chen, Xi Jing; Black, T. Andrew

    2013-01-01

    To investigate the importance of autumn phenology in controlling interannual variability of forest net ecosystem productivity (NEP) and to derive new phenological metrics to explain the interannual variability of NEP. North America and Europe. Flux data from nine deciduous broadleaf forests (DBF)...

  3. National assessment of geologic carbon dioxide storage resources: allocations of assessed areas to Federal lands

    Science.gov (United States)

    Buursink, Marc L.; Cahan, Steven M.; Warwick, Peter D.

    2015-01-01

    Following the geologic basin-scale assessment of technically accessible carbon dioxide storage resources in onshore areas and State waters of the United States, the U.S. Geological Survey estimated that an area of about 130 million acres (or about 200,000 square miles) of Federal lands overlies these storage resources. Consequently, about 18 percent of the assessed area associated with storage resources is allocated to Federal land management. Assessed areas are allocated to four other general land-ownership categories as follows: State lands about 4.5 percent, Tribal lands about 2.4 percent, private and other lands about 72 percent, and offshore areas about 2.6 percent.

  4. Relevance of methodological choices for accounting of land use change carbon fluxes

    Science.gov (United States)

    Hansis, Eberhard; Davis, Steven J.; Pongratz, Julia

    2015-08-01

    Accounting for carbon fluxes from land use and land cover change (LULCC) generally requires choosing from multiple options of how to attribute the fluxes to regions and to LULCC activities. Applying a newly developed and spatially explicit bookkeeping model BLUE (bookkeeping of land use emissions), we quantify LULCC fluxes and attribute them to land use activities and countries by a range of different accounting methods. We present results with respect to a Kyoto Protocol-like "commitment" accounting period, using land use emissions of 2008-2012 as an example scenario. We assess the effect of accounting methods that vary (1) the temporal evolution of carbon stocks, (2) the state of the carbon stocks at the beginning of the period, (3) the temporal attribution of carbon fluxes during the period, and (4) treatment of LULCC fluxes that occurred prior to the beginning of the period. We show that the methodological choices result in grossly different estimates of carbon fluxes for the different attribution definitions.

  5. Projected carbon stocks in the conterminous USA with land use and variable fire regimes.

    Science.gov (United States)

    Bachelet, Dominique; Ferschweiler, Ken; Sheehan, Timothy J; Sleeter, Benjamin M; Zhu, Zhiliang

    2015-12-01

    The dynamic global vegetation model (DGVM) MC2 was run over the conterminous USA at 30 arc sec (~800 m) to simulate the impacts of nine climate futures generated by 3GCMs (CSIRO, MIROC and CGCM3) using 3 emission scenarios (A2, A1B and B1) in the context of the LandCarbon national carbon sequestration assessment. It first simulated potential vegetation dynamics from coast to coast assuming no human impacts and naturally occurring wildfires. A moderate effect of increased atmospheric CO2 on water use efficiency and growth enhanced carbon sequestration but did not greatly influence woody encroachment. The wildfires maintained prairie-forest ecotones in the Great Plains. With simulated fire suppression, the number and impacts of wildfires was reduced as only catastrophic fires were allowed to escape. This greatly increased the expansion of forests and woodlands across the western USA and some of the ecotones disappeared. However, when fires did occur, their impacts (both extent and biomass consumed) were very large. We also evaluated the relative influence of human land use including forest and crop harvest by running the DGVM with land use (and fire suppression) and simple land management rules. From 2041 through 2060, carbon stocks (live biomass, soil and dead biomass) of US terrestrial ecosystems varied between 155 and 162 Pg C across the three emission scenarios when potential natural vegetation was simulated. With land use, periodic harvest of croplands and timberlands as well as the prevention of woody expansion across the West reduced carbon stocks to a range of 122-126 Pg C, while effective fire suppression reduced fire emissions by about 50%. Despite the simplicity of our approach, the differences between the size of the carbon stocks confirm other reports of the importance of land use on the carbon cycle over climate change.

  6. Soil warming effect on net ecosystem exchange of carbon dioxide during the transition from winter carbon source to spring carbon sink in a temperate urban lawn

    Institute of Scientific and Technical Information of China (English)

    Xiaoping Zhou; Xiaoke Wang; Lei Tong; Hongxing Zhang; Fei Lu; Feixiang Zheng; Peiqiang Hou; Wenzhi Song; Zhiyun Ouyang

    2012-01-01

    The significant wanning in urban environment caused by the combined effects of global warming and heat island has stimulated widely development of urban vegetations.However,it is less known of the climate feedback of urban lawn in warmed environment.Soil warming effect on net ecosystem exchange (NEE) of carbon dioxide during the transition period from winter to spring was investigated in a temperate urban lawn in Beijing,China.The NEE (negative for uptake) under soil warming treatment (temperature was about 5℃ higher than the ambient treatment as a control) was-0.71 μmol/(m2·sec),the ecosytem was a CO2 sink under soil warming treatment,the lawn ecosystem under the control was a CO2 source (0.13 μmol/(m2·sec)),indicating that the lawn ecosystem would provide a negative feedback to global warming.There was no significant effect of soil warming on nocturnal NEE (i.e.,ecosystem respiration),although the soil temperature sensitivity (Q10) of ecosystem respiration under soil warming treatment was 3.86,much lower than that in the control (7.03).The CO2 uptake was significantly increased by soil warming treatment that was attributed to about 100% increase of α (apparent quantum yield) and Amax (maximutn rate of photosynthesis).Our results indicated that the response of photosynthesis in urban lawn is much more sensitive to global warming than respiration in the transition period.

  7. Impact of cloudiness on net ecosystem exchange of carbon dioxide in different types of forest ecosystems in China

    Science.gov (United States)

    Zhang, M.; Yu, G.-R.; Zhang, L.-M.; Sun, X.-M.; Wen, X.-F.; Han, S.-J.; Yan, J.-H.

    2010-02-01

    Clouds can significantly affect carbon exchange process between forest ecosystems and the atmosphere by influencing the quantity and quality of solar radiation received by ecosystem's surface and other environmental factors. In this study, we analyzed the effects of cloudiness on net ecosystem exchange of carbon dioxide (NEE) in a temperate broad-leaved Korean pine mixed forest at Changbaishan (CBS) and a subtropical evergreen broad-leaved forest at Dinghushan (DHS), based on the flux data obtained during June-August from 2003 to 2006. The results showed that the response of NEE of forest ecosystems to photosynthetically active radiation (PAR) differed under clear skies and cloudy skies. Compared with clear skies, the light-saturated maximum photosynthetic rate (Pec,max) at CBS under cloudy skies during mid-growing season (from June to August) increased by 34%, 25%, 4% and 11% in 2003, 2004, 2005 and 2006, respectively. In contrast, Pec,max of the forest ecosystem at DHS was higher under clear skies than under cloudy skies from 2004 to 2006. When the clearness index (kt) ranged between 0.4 and 0.6, the NEE reached its maximum at both CBS and DHS. However, the NEE decreased more dramatically at CBS than at DHS when kt exceeded 0.6. The results indicate that cloudy sky conditions are beneficial to net carbon uptake in the temperate forest ecosystem and the subtropical forest ecosystem. Under clear skies, vapor pressure deficit (VPD) and air temperature increased due to strong light. These environmental conditions led to greater decrease in gross ecosystem photosynthesis (GEP) and greater increase in ecosystem respiration (Re) at CBS than at DHS. As a result, clear sky conditions caused more reduction of NEE in the temperate forest ecosystem than in the subtropical forest ecosystem. The response of NEE of different forest ecosystems to the changes in cloudiness is an important factor that should be included in evaluating regional carbon budgets under climate change

  8. Carbon cycling and net ecosystem production at an early stage of secondary succession in an abandoned coppice forest.

    Science.gov (United States)

    Ohtsuka, Toshiyuki; Shizu, Yoko; Nishiwaki, Ai; Yashiro, Yuichiro; Koizumi, Hiroshi

    2010-07-01

    Secondary mixed forests are one of the dominant forest cover types in human-dominated temperate regions. However, our understanding of how secondary succession affects carbon cycling and carbon sequestration in these ecosystems is limited. We studied carbon cycling and net ecosystem production (NEP) over 4 years (2004-2008) in a cool-temperate deciduous forest at an early stage of secondary succession (18 years after clear-cutting). Net primary production of the 18-year-old forest in this study was 5.2 tC ha(-1 )year(-1), including below-ground coarse roots; this was partitioned into 2.5 tC ha(-1 )year(-1) biomass increment, 1.6 tC ha(-1 )year(-1) foliage litter, and 1.0 tC ha(-1 )year(-1) other woody detritus. The total amount of annual soil surface CO(2) efflux was 6.8 tC ha(-1 )year(-1), which included root respiration (1.9 tC ha(-1 )year(-1)) and heterotrophic respiration (RH) from soils (4.9 tC ha(-1 )year(-1)). The 18-year forest at this study site exhibited a great increase in biomass pool as a result of considerable total tree growth and low mortality of tree stems. In contrast, the soil organic matter (SOM) pool decreased markedly (-1.6 tC ha(-1 )year(-1)), although further study of below-ground detritus production and RH of SOM decomposition is needed. This young 18-year forest was a weak carbon sink (0.9 tC ha(-1 )year(-1)) at this stage of secondary succession. The NEP of this 18-year forest is likely to increase gradually because biomass increases with tree growth and with the improvement of the SOM pool through increasing litter and dead wood production with stand development.

  9. Estimation of net ecosystem carbon exchange for the conterminous United States by combining MODIS and AmeriFlux data

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Jingfeng; Zhuang, Qianlai; Baldocchi, Dennis D.; Bolstad, Paul V.; Burns, Sean P.; Chen, Jiquan; Cook, David R.; Curtis, Peter S.; Drake, Bert G.; Foster, David R.; Gu, Lianhong; Hadley, Julian L.; Hollinger, David Y.; Katul, Gabriel G.; Law, Beverly E.; Litvak, Marcy; Ma, Siyan; Martin, Timothy A.; Matamala, Roser; McNulty, Steve; Meyers, Tilden P.; Monson, Russell K.; Munger, J. William; Noormets, Asko; Oechel, Walter C.; Oren, Ram; Richardson, Andrew D.; Schmid, Hans Peter; Scott, Russell L.; Starr, Gregory; Sun, Ge; Suyker, Andrew E.; Torn, Margaret S.; Paw, Kyaw; Verma, Shashi B.; Wharton, Sonia; Wofsy, Steven C.

    2008-10-01

    Eddy covariance flux towers provide continuous measurements of net ecosystem carbon exchange (NEE) for a wide range of climate and biome types. However, these measurements only represent the carbon fluxes at the scale of the tower footprint. To quantify the net exchange of carbon dioxide between the terrestrial biosphere and the atmosphere for regions or continents, flux tower measurements need to be extrapolated to these large areas. Here we used remotely sensed data from the Moderate Resolution Imaging Spectrometer (MODIS) instrument on board the National Aeronautics and Space Administration's (NASA) Terra satellite to scale up AmeriFlux NEE measurements to the continental scale. We first combined MODIS and AmeriFlux data for representative U.S. ecosystems to develop a predictive NEE model using a modified regression tree approach. The predictive model was trained and validated using eddy flux NEE data over the periods 2000-2004 and 2005-2006, respectively. We found that the model predicted NEE well (r = 0.73, p < 0.001). We then applied the model to the continental scale and estimated NEE for each 1 km x 1 km cell across the conterminous U.S. for each 8-day interval in 2005 using spatially explicit MODIS data. The model generally captured the expected spatial and seasonal patterns of NEE as determined from measurements and the literature. Our study demonstrated that our empirical approach is effective for scaling up eddy flux NEE measurements to the continental scale and producing wall-to-wall NEE estimates across multiple biomes. Our estimates may provide an independent dataset from simulations with biogeochemical models and inverse modeling approaches for examining the spatiotemporal patterns of NEE and constraining terrestrial carbon budgets over large areas.

  10. Estimation of Net Ecosystem Carbon Exchange for the Conterminous UnitedStates by Combining MODIS and AmeriFlux Data

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Jingfeng; Zhuang, Qianlai; Baldocchi, Dennis D.; Law, Beverly E.; Richardson, Andrew D.; Chen, Jiquan; Oren, Ram; Starr, Gregory; Noormets, Asko; Ma, Siyan; Verma, Shashi B.; Wharton, Sonia; Wofsy, Steven C.; Bolstad, Paul V.; Burns, Sean P.; Cook, David R.; Curtis, Peter S.; Drake, Bert G.; Falk, Matthias; Fischer, Marc L.; Foster, David R.; Gu, Lianhong; Hadley, Julian L.; Hollinger, David Y.; Katul, Gabriel G.; Litvak, Marcy; Martin, Timothy A.; Matamala, Roser; McNulty, Steve; Meyers, Tilden P.; Monson, Russell K.; Munger, J. William; Oechel, Walter C.; U, Kyaw Tha Paw; Schmid, Hans Peter; Scott, Russell L.; Sun, Ge; Suyker, Andrew E.; Torn, Margaret S.

    2009-03-06

    Eddy covariance flux towers provide continuous measurements of net ecosystem carbon exchange (NEE) for a wide range of climate and biome types. However, these measurements only represent the carbon fluxes at the scale of the tower footprint. To quantify the net exchange of carbon dioxide between the terrestrial biosphere and the atmosphere for regions or continents, flux tower measurements need to be extrapolated to these large areas. Here we used remotely-sensed data from the Moderate Resolution Imaging Spectrometer (MODIS) instrument on board NASA's Terra satellite to scale up AmeriFlux NEE measurements to the continental scale. We first combined MODIS and AmeriFlux data for representative U.S. ecosystems to develop a predictive NEE model using a regression tree approach. The predictive model was trained and validated using NEE data over the periods 2000-2004 and 2005-2006, respectively. We found that the model predicted NEE reasonably well at the site level. We then applied the model to the continental scale and estimated NEE for each 1 km x 1 km cell across the conterminous U.S. for each 8-day period in 2005 using spatially-explicit MODIS data. The model generally captured the expected spatial and seasonal patterns of NEE. Our study demonstrated that our empirical approach is effective for scaling up eddy flux NEE measurements to the continental scale and producing wall-to-wall NEE estimates across multiple biomes. Our estimates may provide an independent dataset from simulations with biogeochemical models and inverse modeling approaches for examining the spatiotemporal patterns of NEE and constraining terrestrial carbon budgets for large areas.

  11. Bioenergy and the importance of land use policy in a carbon-constrained world

    Energy Technology Data Exchange (ETDEWEB)

    Calvin, Katherine V.; Edmonds, James A.; Wise, Marshall A.

    2010-06-01

    Policies aimed at limiting anthropogenic climate change would result in significant transformations of the energy and land-use systems. However, increasing the demand for bioenergy could have a tremendous impact on land use, and can result in land clearing and deforestation. Wise et al. (2009a,b) analyzed an idealized policy to limit the indirect land use change emissions from bioenergy. The policy, while effective, would be difficult, if not impossible, to implement in the real world. In this paper, we consider several different land use policies that deviate from this first-best, using the Joint Global Change Research Institute’s Global Change Assessment Model (GCAM). Specifically, these new frameworks are (1) a policy that focuses on just the above-ground or vegetative terrestrial carbon rather than the total carbon, (2) policies that focus exclusively on incentivizing and protecting forestland, and (3) policies that apply an economic penalty on the use of biomass as a proxy to limit indirect land use change emissions. For each policy, we examine its impact on land use, land-use change emissions, atmospheric CO2 concentrations, agricultural supply, and food prices.

  12. Carbon dioxide flux and net primary production of a boreal treed bog: responses to warming and water table manipulations

    Science.gov (United States)

    Munir, T. M.; Perkins, M.; Kaing, E.; Strack, M.

    2014-09-01

    Mid-latitude treed bogs are significant carbon (C) stocks and are highly sensitive to global climate change. In a dry continental treed bog, we compared three sites; control, recent (1-3 years; experimental) and older drained (10-13 years; drained) with water levels at 38, 74 and 120 cm below the surface, respectively. At each site we measured carbon dioxide (CO2) fluxes and tree root respiration (Rr) (across hummock-hollow microtopography of the forest floor) and net primary production (NPP) of trees during the growing seasons (May to October) of 2011-2013. The carbon (C) balance was calculated by adding net CO2 exchange of the forest floor (NEff-Rr) to the NPP of the trees. From cooler and wetter 2011 to driest and warmest 2013, The control site was a~C sink of 92, 70 and 76 g m-2, experimental site was a C source of 14, 57 and 135 g m-2, and drained site was a progressively smaller source of 26, 23 and 13 g m-2, respectively. Although all microforms at the experimental site had large net CO2 emissions, the longer-term drainage and deeper water level at the drained site resulted in the replacement of mosses with vascular plants (shrubs) at the hummocks and lichens at the hollows leading to the highest CO2 uptake at drained hummocks and significant losses at hollows. The tree NPP was highest at the drained site. We also quantified the impact of climatic warming at all water table treatments by equipping additional plots with open-top chambers (OTCs) that caused a passive warming on average of ∼1 °C and differential air warming of ∼6 °C (at mid-day full sun) across the study years. Warming significantly enhanced the shrub growth and CO2 sink function of the drained hummocks (exceeding the cumulative respiration losses at hollows induced by the lowered water level × warming). There was an interaction of water level with warming across hummocks that resulted in largest net CO2 uptake at warmed drained hummocks. Thus in 2013, the warming treatment enhanced the

  13. The carbon copy of human activities : how long-term land use explains spatial variability of soil organic carbon stocks at multiple scales

    NARCIS (Netherlands)

    Schulp, C.J.E.

    2009-01-01

    Invloed van landgebruik, landgebruik-geschiedenis en management op de koolstofvoorraad in de bodem in Nederland.The carbon copy of human activities - how long-term land use explains spatial variability of soil organic carbon stocks at multiple scales.

  14. Net carbon uptake has increased through warming-induced changes in temperate forest phenology

    Energy Technology Data Exchange (ETDEWEB)

    Keenan, Trevor [Harvard University; Gray, Josh [Boston University; Friedl, Mark [Boston University; Toomey, Michael [Harvard University; Bohrer, Gil [Ohio State University; Hollinger, David [USDA Forest Service, Northern Research Station; Munger, J. William [Harvard University; OKeefe, John [Harvard Forest (Harvard University), Massachusetts; Hans, Schmid [Karlsruhe Institute of Technology, Karlsruhe, Germany; Wing, Ian [Boston University; Yang, Bai [ORNL; Richardson, Andrew D. [Harvard University

    2014-01-01

    The timing of phenological events exerts a strong control over ecosystem function and leads to multiple feedbacks to the climate system1. Phenology is inherently sensitive to temperature (though the exact sensitivity is disputed2) and recent warming is reported to have led to earlier spring, later autumn3,4 and increased vegetation activity5,6. Such greening could be expected to enhance ecosystem carbon uptake7,8, though reports also suggest decreased uptake for boreal forests4,9. Here we assess changes in phenology of temperate forests over the eastern US during the past two decades, and quantify the resulting changes in forest carbon storage. We combine long-term ground observations of phenology, satellite indices, and ecosystem-scale carbon dioxide flux measurements, along with 18 terrestrial biosphere models. We observe a strong trend of earlier spring and later autumn. In contrast to previous suggestions4,9 we show that carbon uptake through photosynthesis increased considerably more than carbon release through respiration for both an earlier spring and later autumn. The terrestrial biosphere models tested misrepresent the temperature sensitivity of phenology, and thus the effect on carbon uptake. Our analysis of the temperature-phenology-carbon coupling suggests a current and possible future enhancement of forest carbon uptake due to changes in phenology. This constitutes a negative feedback to climate change, and is serving to slow the rate of warming.

  15. Land cover uncertainty generates substantial uncertainty in earth system model carbon and climate projections

    Science.gov (United States)

    Di Vittorio, Alan; Mao, Jiafu; Shi, Xiaoying

    2017-04-01

    Several climate adaptation and mitigation strategies incorporate Land Use and Land Cover Change (LULCC) to address global carbon balance and climate. However, LULCC is not consistent across the CMIP5 model simulations because only the land use input is harmonized. The associated LULCC uncertainty generates uncertainty in regional and global carbon and climate dynamics that obfuscates the evaluation of whether such strategies are effective in meeting their goals. For example, the integrated Earth System Model (iESM) overestimates 2004 atmospheric CO2 concentration by 14 ppmv, and we explore the contribution of historical LULCC uncertainty to this bias in relation to the effects of CO2 fertilization, climate change, and nitrogen deposition on terrestrial carbon. Using identical land use input, a chronologically referenced LULCC that accounts for pasture, as opposed to the default year-2000 referenced LULCC, increases this bias to 20 ppmv because more forest needs to be cleared for land use. Assuming maximum forest retention for all land conversion reduces the new bias to 19 ppmv, while minimum forest retention increases the new bias to 24 ppmv. There is a 33 Pg land carbon uncertainty range due to maximizing versus minimizing forest area, which is 80% of the estimated 41 PgC gain in land carbon due to CO2 fertilization combined with climate change from 1850-2004 and 150% of the estimated 22 PgC gain due to nitrogen deposition. These results demonstrate that LULCC accuracy and uncertainty are critical for estimating the carbon cycle, and also that LULCC may be an important lever for constraining global carbon estimates. Furthermore, different land conversion assumptions can generate local differences of over 1.0 °C between the two forest retention cases with less than 5% difference in tree cover within a grid cell. Whether these temperature differences are positive or negative depends more on region than on latitude. Sensible heat appears to be more sensitive than

  16. Impacts of forest and land management on biodiversity and carbon

    Science.gov (United States)

    Valerie Kapos; Werner A. Kurz; Toby Gardner; Joice Ferreira; Manuel Guariguata; Lian Pin Koh; Stephanie Mansourian; John A. Parrotta; Nokea Sasaki; Christine B. Schmitt; Jos Barlow; Markku Kanninen; Kimiko Okabe; Yude Pan; Ian D. Thompson; Nathalie. van Vliet

    2012-01-01

    Changes in the management of forest and non-forest land can contribute significantly to reducing emissions from deforestation and forest degradation. Such changes can include both forest management actions - such as improving the protection and restoration of existing forests, introducing ecologically responsible logging practices and regenerating forest on degraded...

  17. What does nonforest land contribute to the global carbon balance?

    Science.gov (United States)

    Jennifer C. Jenkins; Rachel Riemann

    2002-01-01

    An inventory of land traditionally called "nonforest" and therefore not sampled by the Forest Inventory and Analysis (FIA) program was implemented by the FIA unit at the Northeastern Station in 1999 for five counties in Maryland. Biomass and biomass increment were estimated from the nonforest inventory data using techniques developed for application to large-...

  18. Land use impacts of low-carbon energy system transition - the case of UK bioenergy deployment under the Carbon Plan

    Science.gov (United States)

    Konadu, D. D.; Sobral Mourao, Z.; Lupton, R.; Skelton, S.

    2015-12-01

    The UK Department of Energy and Climate Change has developed four low-carbon energy transition pathways - the Carbon Plan - towards achieving the legally binding 80% territorial greenhouse gas emissions reduction, stipulated in the 2008 Climate Change Act by 2050. All the pathways require increase in bioenergy deployment, of which a significant amount could be indigenously sourced from crops. But will increased domestic production of energy crops conflict with other land use and ecosystem priorities? To address this question, a coupled analysis of the four energy transition pathways and land use has been developed using an integrated resource accounting platform called ForeseerTM. The two systems are connected by the bioenergy component, and are projected forward in time to 2050, under different scenarios of energy crop composition and yield, and accounting for various constraints on land use for agriculture and ecosystem services. The results show between 7 and 61% of UK agricultural land could be required to meet bioenergy deployment projections under different combinations of crop yield and compositions for the transition pathways. This could result in competition for land for food production and other socio-economic and ecological land uses. Consequently, the potential role of bioenergy in achieving UK emissions reduction targets may face significant deployment challenges.

  19. The influence of land use on soil organic carbon and nitrogen content and redox potential

    DEFF Research Database (Denmark)

    Kusliene, Gedrime

    2010-01-01

    The aim of the research was to evaluate organic matter status in the soil according to the organic carbon content, total and mineral nitrogen amounts, carbon to nitrogen (C:N) ratio and redox potential depending on land usage and plant spieces. Soil samples were taken from the fields under...... different farming systems (conventional and organic) as well as abandoned lands. We choose the plants of two botanical species (Poaceae and Fabaceae) in organic and conventional farming systems as well as abandoned lands. Experimental results show that the best soil organic matter status according...... to the investigated indexes is in the soils of conventional and orgaic farming systems occupied with mixtures of Poaceae and Fabaceae and the worst - in the soils of abandoned Poaceae meadowa. In the abandoned lands, Fabaceae (galega) had better influence on soil organic matter status than Poaceae....

  20. Attributing land-use change carbon emissions to exported biomass

    Energy Technology Data Exchange (ETDEWEB)

    Saikku, Laura, E-mail: laura.saikku@helsinki.fi [University of Helsinki, P.O Box 65, 00014 University of Helsinki (Finland); Soimakallio, Sampo, E-mail: sampo.soimakallio@vtt.fi [VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT (Finland); Pingoud, Kim, E-mail: kim.pingoud@vtt.fi [VTT Technical Research Centre of Finland, P.O. Box 1000, 02044 VTT (Finland)

    2012-11-15

    In this study, a simple, transparent and robust method is developed in which land-use change (LUC) emissions are retrospectively attributed to exported biomass products based on the agricultural area occupied for the production. LUC emissions account for approximately one-fifth of current greenhouse gas emissions. Increasing agricultural exports are becoming an important driver of deforestation. Brazil and Indonesia are used as case studies due to their significant deforestation in recent years. According to our study, in 2007, approximately 32% and 15% of the total agricultural land harvested and LUC emissions in Brazil and Indonesia respectively were due to exports. The most important exported single items with regard to deforestation were palm oil for Indonesia and bovine meat for Brazil. To reduce greenhouse gas (GHG) emissions effectively worldwide, leakage of emissions should be avoided. This can be done, for example, by attributing embodied LUC emissions to exported biomass products. With the approach developed in this study, controversial attribution between direct and indirect LUC and amortization of emissions over the product life cycle can be overcome, as the method operates on an average basis and annual level. The approach could be considered in the context of the UNFCCC climate policy instead of, or alongside with, other instruments aimed at reducing deforestation. However, the quality of the data should be improved and some methodological issues, such as the allocation procedure in multiproduct systems and the possible dilution effect through third parties not committed to emission reduction targets, should be considered. - Highlights: Black-Right-Pointing-Pointer CO{sub 2} emissions from land use changes are highly important. Black-Right-Pointing-Pointer Attribution of land use changes for products is difficult. Black-Right-Pointing-Pointer Simple and robust method is developed to attribute land use change emissions.

  1. A semi-analytical solution to accelerate spin-up of a coupled carbon and nitrogen land model to steady state

    Directory of Open Access Journals (Sweden)

    J. Xia

    2012-04-01

    Full Text Available The spin-up of land models to steady state of coupled carbon-nitrogen processes is computationally so costly that it becomes a~bottleneck issue for global analysis. In this study, we introduced a semi-analytical solution (SAS for the spin-up issue. SAS is fundamentally based on the analytic solution to a set of equations that describe carbon transfers within ecosystems over time. SAS is implemented by three steps: (1 having an initial spin-up with prior pool-size values until net primary productivity (NPP reaches steady state, (2 calculating quasi steady-state pool sizes by letting fluxes of the equations equal zero, and (3 having a final spin-up to meet the criterion of steady state. Step 2 is enabled by averaged time-varying variables over one period of repeated driving forcings. SAS was applied to both site-level and global scale spin-up of the Australian Community Atmosphere Biosphere Land Exchange (CABLE model. For the carbon-cycle-only simulations, SAS saved 95.7% and 92.4% of computational time for site-level and global spin-up, respectively, in comparison with the traditional method. For the carbon-nitrogen-coupled simulations, SAS reduced computational cost by 84.5% and 86.6% for site-level and global spin-up, respectively. The estimated steady-state pool sizes represent the ecosystem carbon storage capacity, which was 12.1 kg C m−2 with the coupled carbon-nitrogen global model, 14.6% lower than that with the carbon-only model. The nitrogen down-regulation in modeled carbon storage is partly due to the 4.6% decrease in carbon influx (i.e., net primary productivity and partly due to the 10.5% reduction in residence times. This steady-state analysis accelerated by the SAS method can facilitate comparative studies of structural differences in determining the ecosystem carbon storage capacity among biogeochemical models. Overall, the computational efficiency of SAS potentially permits many global analyses that are impossible

  2. Role of CO2, climate and land use in regulating the seasonal amplitude increase of carbon fluxes in terrestrial ecosystems: a multimodel analysis

    Science.gov (United States)

    Zhao, Fang; Zeng, Ning; Asrar, Ghassem; Friedlingstein, Pierre; Ito, Akihiko; Jain, Atul; Kalnay, Eugenia; Kato, Etsushi; Koven, Charles D.; Poulter, Ben; Rafique, Rashid; Sitch, Stephen; Shu, Shijie; Stocker, Beni; Viovy, Nicolas; Wiltshire, Andy; Zaehle, Sonke

    2016-09-01

    We examined the net terrestrial carbon flux to the atmosphere (FTA) simulated by nine models from the TRENDY dynamic global vegetation model project for its seasonal cycle and amplitude trend during 1961-2012. While some models exhibit similar phase and amplitude compared to atmospheric inversions, with spring drawdown and autumn rebound, others tend to rebound early in summer. The model ensemble mean underestimates the magnitude of the seasonal cycle by 40 % compared to atmospheric inversions. Global FTA amplitude increase (19 ± 8 %) and its decadal variability from the model ensemble are generally consistent with constraints from surface atmosphere observations. However, models disagree on attribution of this long-term amplitude increase, with factorial experiments attributing 83 ± 56 %, -3 ± 74 and 20 ± 30 % to rising CO2, climate change and land use/cover change, respectively. Seven out of the nine models suggest that CO2 fertilization is the strongest control - with the notable exception of VEGAS, which attributes approximately equally to the three factors. Generally, all models display an enhanced seasonality over the boreal region in response to high-latitude warming, but a negative climate contribution from part of the Northern Hemisphere temperate region, and the net result is a divergence over climate change effect. Six of the nine models show that land use/cover change amplifies the seasonal cycle of global FTA: some are due to forest regrowth, while others are caused by crop expansion or agricultural intensification, as revealed by their divergent spatial patterns. We also discovered a moderate cross-model correlation between FTA amplitude increase and increase in land carbon sink (R2 = 0.61). Our results suggest that models can show similar results in some benchmarks with different underlying mechanisms; therefore, the spatial traits of CO2 fertilization, climate change and land use/cover changes are crucial in determining the right mechanisms in

  3. Impact of Changes in Diffuse Radiation on the Global Land Carbon Sink, 1901-2100

    Science.gov (United States)

    Mercado, L.; Bellouin, N.; Sitch, S.; Boucher, O.; Huntingford, C.; Wild, M.; Cox, P. M.

    2009-04-01

    Recent observational and theoretical studies have shown that changes in surface radiation that lead to increasing diffuse surface irradiance, enhance plant photosynthesis (Gu et al., 2003, Niyogi et al., 2004, Oliveira et al., 2007, Roderick et al., 2001). Solar radiation reaching the land surface has changed over the industrial era due to aerosols emitted from volcanoes and various anthropogenic sources (Kvalevag and Myhre, 2007). Such changes in total surface radiation are accompanied by changes in direct and diffuse surface solar radiation. Current global climate-carbon models do include the effects of changes in total surface radiation on the land biosphere but neglect the positive effects of increasing diffuse fraction on plant photosynthesis. In this study we estimate for the first time, the impact of variations in diffuse fraction on the land carbon sink using a global model (Mercado et al., 2007) modified to account for the effects of variations in both direct and diffuse radiation on canopy photosynthesis. We use meteorological forcing from the Climate Research Unit Data set. Additionally short wave and photosynthetic active radiation are reconstructed from the Hadley centre climate model, which accounts for the scattering and absorption of light by tropospheric and stratospheric aerosols and change in cloud properties due to indirect aerosol effects. References Gu L.H., Baldocchi D.D., Wofsy S.C., Munger J.W., Michalsky J.J., Urbanski S.P. & Boden T.A. (2003) Response of a deciduous forest to the Mount Pinatubo eruption: Enhanced photosynthesis. Science, 299, 2035-2038. M. M. Kvalevag and G. Myhre, J. Clim. 20, 4874 (2007). Mercado L.M., Huntingford C., Gash J.H.C., Cox P.M. & Jogireddy V. (2007) Improving the representation of radiation interception and photosynthesis for climate model applications. Tellus Series B-Chemical and Physical Meteorology, 59, 553-565. Niyogi D., Chang H.I., Saxena V.K., Holt T., Alapaty K., Booker F., Chen F., Davis K

  4. Impact of tropical land use change on soil organic carbon stocks - a meta-analysis

    OpenAIRE

    Don, Axel; Schumacher, Jens; Freibauer, Annette

    2010-01-01

    Abstract Land use changes are the second largest source of human induced greenhouse gas emission, mainly due to deforestation in the tropics and sub-tropics. CO2 emissions result from biomass and soil organic carbon (SOC) losses and may be offset with afforestation programs. However, the effect of land use changes on SOC is poorly quantified due to insufficient data quality (only SOC concentrations and no SOC stocks, shallow sampling depth) and representativeness. In a global meta-...

  5. The computation of carbon emissions due to the net payload on a truck

    DEFF Research Database (Denmark)

    Turkensteen, Marcel

    , it is necessary to compute the carbon emissions of these decisions. Current studies are only able to determine this for very specific conditions, such as a given vehicle under given driving conditions, and they may require many input parameters. Therefore, this paper presents a simple and broadly applicable...... emission computation tool. We determine the share of the carbon emissions of fully loaded vehicles due to the weight of the load on the vehicle, i.e. the load‐based emission percentage (LBEP). We conduct a review study on papers that report on carbon emissions or fuel consumption for different load factors...

  6. Managing Carbon on Federal Public Lands: Opportunities and Challenges in Southwestern Colorado

    Science.gov (United States)

    Dilling, Lisa; Kelsey, Katharine C.; Fernandez, Daniel P.; Huang, Yin D.; Milford, Jana B.; Neff, Jason C.

    2016-08-01

    Federal lands in the United States have been identified as important areas where forests could be managed to enhance carbon storage and help mitigate climate change. However, there has been little work examining the context for decision making for carbon in a multiple-use public land environment, and how science can support decision making. This case study of the San Juan National Forest and the Bureau of Land Management Tres Rios Field Office in southwestern Colorado examines whether land managers in these offices have adequate tools, information, and management flexibility to practice effective carbon stewardship. To understand how carbon was distributed on the management landscape we added a newly developed carbon map for the SJNF-TRFO area based on Landsat TM texture information (Kelsey and Neff in Remote Sens 6:6407-6422. doi: 10.3390/rs6076407, 2014). We estimate that only about 22 % of the aboveground carbon in the SJNF-TRFO is in areas designated for active management, whereas about 38 % is in areas with limited management opportunities, and 29 % is in areas where natural processes should dominate. To project the effects of forest management actions on carbon storage, staff of the SJNF are expected to use the Forest Vegetation Simulator (FVS) and extensions. While identifying FVS as the best tool generally available for this purpose, the users and developers we interviewed highlighted the limitations of applying an empirically based model over long time horizons. Future research to improve information on carbon storage should focus on locations and types of vegetation where carbon management is feasible and aligns with other management priorities.

  7. [Impact of land use type on stability and organic carbon of soil aggregates in Jinyun Mountain].

    Science.gov (United States)

    Li, Jian-Lin; Jiang, Chang-Sheng; Hao, Qing-Ju

    2014-12-01

    Soil aggregates have the important effect on soil fertility, soil quality and the sustainable utilization of soil, and they are the mass bases of water and fertilizer retention ability of soil and the supply or release of soil nutrients. In this paper, in order to study the impact of land use type on stability and organic carbon of soil aggregates in Jinyun Mountain, we separated four land use types of soil, which are woodland, abandoned land, orchard and sloping farmland by wet sieving method, then we got the proportion of large macroaggregates (> 2 mm), small macroaggregates (0.25-2 mm), microaggregates (53 μm-0.25 mm) and silt + clay (organic carbon in each aggregate fraction in soil depth of 0-60 cm and calculated the total content of organic carbon of all aggregates fraction in each soil. The results showed that reclamation of woodland will lead to fragmentation of macroaggregates and deterioration of soil structure, and the proportion of macroaggrgates (> 0.25 mm) were 44.62% and 32.28% respectively in the soils of orchard and sloping farmland, which reduced 38.58% (P soil fraction from silt + clay to large macroaggregates and small macroaggregates, so it will improve the soil structure. MWD (mean weight diameter) and GMD (geometric mean diameter) are important indicators of evaluating the stability of soil aggregates. We found the MWD and GWD in soil depth of 0-60 cm in orchards and sloping farmland were significantly lower than those in woodland (P soil aggregates, and they will be separated more easily by water. However, after changing the sloping farmland to abandoned land will enhance the stability of soil aggregates, and improve the ability of soil to resist external damage. The organic carbon content in each soil aggregate of four land use types decreased with the increase of soil depth. In soil depth of 0-60 cm, the storage of organic carbon of large macroaggregates in each soil are in orders of woodland (14.98 Mg x hm(-2)) > abandoned land (8.71 Mg

  8. Atmospheric carbon exchange associated with vegetation and soils in urban and suburban land uses

    Energy Technology Data Exchange (ETDEWEB)

    Rowntree, R.A. [Northeastern Forest Experiment Station, Berkeley, CA (United States)

    1993-12-31

    In studies of the global C cycle prior to the 1980s, urban ecosystems were largely ignored, in part because them were inadequate measures of phytomass and soil carbon for the various land uses associated with cities. In the last decade, progress has been made in gathering urban vegetation data and recently, estimates of urban land use carbon storage and fluxes have been attempted. Demographic trends in many countries suggest that urban areas are growing. Thus it is important to discover the appropriate concepts and methods for understanding greenhouse gas fluxes from urban-related vegetation and soils.

  9. The effect of atmospheric CO2 concentration on carbon isotope fractionation in C3 land plants

    Science.gov (United States)

    Schubert, Brian A.; Jahren, A. Hope

    2012-11-01

    Because atmospheric carbon dioxide is the ultimate source of all land-plant carbon, workers have suggested that pCO2 level may exert control over the amount of 13C incorporated into plant tissues. However, experiments growing plants under elevated pCO2 in both chamber and field settings, as well as meta-analyses of ecological and agricultural data, have yielded a wide range of estimates for the effect of pCO2 on the net isotopic discrimination (Δδ13Cp) between plant tissue (δ13Cp) and atmospheric CO2 (δ13CCO2). Because plant stomata respond sensitively to plant water status and simultaneously alter the concentration of pCO2 inside the plant (ci) relative to outside the plant (ca), any experiment that lacks environmental control over water availability across treatments could result in additional isotopic variation sufficient to mask or cancel the direct influence of pCO2 on Δδ13Cp. We present new data from plant growth chambers featuring enhanced dynamic stabilization of moisture availability and relative humidity, in addition to providing constant light, nutrient, δ13CCO2, and pCO2 level for up to four weeks of plant growth. Within these chambers, we grew a total of 191 C3 plants (128 Raphanus sativus plants and 63 Arabidopsis thaliana) across fifteen levels of pCO2 ranging from 370 to 4200 ppm. Three types of plant tissue were harvested and analyzed for carbon isotope value: above-ground tissues, below-ground tissues, and leaf-extracted nC31-alkanes. We observed strong hyperbolic correlations (R ⩾ 0.94) between the pCO2 level and Δδ13Cp for each type of plant tissue analyzed; furthermore the linear relationships previously suggested by experiments across small (10-350 ppm) changes in pCO2 (e.g., 300-310 ppm or 350-700 ppm) closely agree with the amount of fractionation per ppm increase in pCO2 calculated from our hyperbolic relationship. In this way, our work is consistent with, and provides a unifying relationship for, previous work on carbon isotopes

  10. Assessing wildlife benefits and carbon storage from restored and natural coastal marshes in the Nisqually River Delta: Determining marsh net ecosystem carbon balance

    Science.gov (United States)

    Anderson, Frank; Bergamaschi, Brian; Windham-Myers, Lisamarie; Woo, Isa; De La Cruz, Susan; Drexler, Judith; Byrd, Kristin; Thorne, Karen M.

    2016-06-24

    Working in partnership since 1996, the U.S. Fish and Wildlife Service and the Nisqually Indian Tribe have restored 902 acres of tidally influenced coastal marsh in the Nisqually River Delta (NRD), making it the largest estuary-restoration project in the Pacific Northwest to date. Marsh restoration increases the capacity of the estuary to support a diversity of wildlife species. Restoration also increases carbon (C) production of marsh plant communities that support food webs for wildlife and can help mitigate climate change through long-term C storage in marsh soils.In 2015, an interdisciplinary team of U.S. Geological Survey (USGS) researchers began to study the benefits of carbon for wetland wildlife and storage in the NRD. Our primary goals are (1) to identify the relative importance of the different carbon sources that support juvenile chinook (Oncorhynchus tshawytscha) food webs and contribute to current and historic peat formation, (2) to determine the net ecosystem carbon balance (NECB) in a reference marsh and a restoration marsh site, and (3) to model the sustainability of the reference and restoration marshes under projected sea-level rise conditions along with historical vegetation change. In this fact sheet, we focus on the main C sources and exchanges to determine NECB, including carbon dioxide (CO2) uptake through plant photosynthesis, the loss of CO2 through plant and soil respiration, emissions of methane (CH4), and the lateral movement or leaching loss of C in tidal waters.

  11. Inter-annual Variability in Net Ecosystem Exchange of Carbon Dioxide and Methane Emissions in a Temperate Freshwater Marsh

    Science.gov (United States)

    Bonneville, M.; Strachan, I.

    2009-05-01

    There exists very little information on greenhouse gas (GHG) exchange in marsh wetlands, especially in temperate climates. Measurements of carbon dioxide (CO2) and methane (CH4) fluxes were made from May 2005 to June 2008 in a temperate freshwater cattail marsh in Eastern Ontario, Canada. The net ecosystem exchange (NEE) of CO2 was measured continuously using the eddy covariance technique, and closed chambers were used to measure CH4 emissions from open water, soil, and vegetated portions of the marsh. Based on NEE, we found that the marsh accumulated 264 g C m-2 from May 2005 to April 2006 and 185 g C m-2 and 308 g C m-2 in 2006-2007 and 2007-2008, respectively. Lower spring temperature in 2005 seems to have delayed the initial growth of cattails and therefore led to a later switchover time from a net CO2 source to a net CO2 sink compared to spring 2006 and 2007. The lower cumulative NEE measured in 2006-2007 is mainly due to the cloudy conditions (i.e. low average incoming photosynthetically active radiation) that occurred through late summer and early fall 2006, which greatly decreased cattail photosynthesis and induced an earlier death of the pants, which in turn resulted in a lower average CO2 uptake compared to the other years. During the 2005, 2006 and 2007 growing seasons, the carbon uptake period was 109, 104, and 116 days in length, which is consistent with the inter-annual variability in NEE observed. The results suggest that the timing of the fall switchover from a net CO2 sink to a net CO2 source is probably the main factor influencing the annual CO2 accumulation. The average CH4 flux measured from open water was 658 mg CH4 m-2 d-1 in 2005, 381 mg CH4 m-2 d-1 in 2006, and 352 mg CH4 m-2 d-1 in 2008. The average CH4 flux from vegetation was 1001 mg CH4 m-2 d-1 in 2005, 1640 mg CH4 m-2 d-1 in 2006, and 1260 mg CH4 m-2 d-1 in 2008. The CH4 flux from soil was only measured in 2006 (255 mg CH4 m-2 d-1) and 2008 (224 mg CH4 m-2 d-1). It is known that the

  12. [Impact of Land Utilization Pattern on Distributing Characters of Labile Organic Carbon in Soil Aggregates in Jinyun Mountain].

    Science.gov (United States)

    Li, Rui; Jiang, Chang-sheng; Hao, Qing-ju

    2015-09-01

    Four land utilization patterns were selected for this study in Jinyun mountain, including subtropical evergreen broad-leaved forest (abbreviation: forest), sloping farmland, orchard and abandoned land. Soil samples were taken every 10 cm in the depth of 60 cm soil and proportions of large macroaggregates (> 2 mm), small macroaggregates (0. 25-2 mm), microaggregates (0. 053 - 0. 25 mm) and silt + clay (organic carbon and labile organic carbon in each aggregate fraction and analyze impacts of land uses on organic carbon and labile organic carbon of soil aggregates. LOC content of four soil aggregates were significantly reduced with the increase of soil depth; in layers of 0-60 cm soil depth, our results showed that LOC contents of forest and abandoned land were higher than orchard and sloping farmland. Reserves of labile organic carbon were estimated by the same soil quality, it revealed that forest (3. 68 Mg.hm-2) > abandoned land (1. 73 Mg.hm-2) > orchard (1. 43 Mg.hm-2) >sloping farmland (0.54 Mg.hm-2) in large macroaggregates, abandoned land (7.77, 5. 01 Mg.hm-2) > forest (4. 96, 2.71 Mg.hm-2) > orchard (3. 33, 21. 10 Mg.hm-2) > sloping farmland (1. 68, 1. 35 Mg.hm-2) in small macroaggregates and microaggregates, and abandoned land(4. 32 Mg.hm-2) > orchard(4. 00 Mg.hm-2) > forest(3. 22 Mg.hm-2) > sloping farmland (2.37 Mg.hm-2) in silt + clay, forest and abandoned land were higher than orchard and sloping farmland in other three soil aggregates except silt + clay. It was observed that the level of organic carbon and labile organic carbon were decreased when bringing forest under cultivation to orchard or farmland, and augments on organic carbon and labile organic carbon were found after exchanging farmland to abandoned land. The most reverses of forest and abandoned land emerged in small macroaggregates, orchard and sloping farmland were in microaggregates. That was, during the transformations of land utilization pattern, soil aggregates with bigger size were

  13. Aerosol optical depth thresholds as a tool to assess diffuse radiation fertilization of the land carbon uptake in China

    Science.gov (United States)

    Yue, Xu; Unger, Nadine

    2017-01-01

    China suffers from frequent haze pollution episodes that alter the surface solar radiation and influence regional carbon uptake by the land biosphere. Here, we apply combined vegetation and radiation modeling and multiple observational datasets to assess the radiative effects of aerosol pollution in China on the regional land carbon uptake for the 2009-2011 period. First, we assess the inherent sensitivity of China's land biosphere to aerosol pollution by defining and calculating two thresholds of aerosol optical depth (AOD) at 550 nm, (i) AODt1, resulting in the maximum net primary productivity (NPP), and (ii) AODt2, such that if local AOD fertilization effect (DFE) always promotes local NPP compared with aerosol-free conditions. Then, we apply the thresholds, satellite data, and interactive vegetation modeling to estimate current impacts of aerosol pollution on land ecosystems. In the northeast, observed AOD is 55 % lower than AODt1, indicating a strong aerosol DFE on local NPP. In the southeastern coastal regions, observed AOD is close to AODt1, suggesting that regional NPP is promoted by the current level of aerosol loading, but that further increases in AOD in this region will weaken the fertilization effects. The North China Plain experiences limited enhancement of NPP by aerosols because observed AOD is 77 % higher than AODt1 but 14 % lower than AODt2. Aerosols always inhibit regional NPP in the southwest because of the persistent high cloud coverage that already substantially reduces the total light availability there. Under clear-sky conditions, simulated NPP shows widespread increases of 20-60 % (35.0 ± 0.9 % on average) by aerosols. Under all-sky conditions, aerosol pollution has spatially contrasting opposite sign effects on NPP from -3 % to +6 % (1.6 ± 0.5 % on average), depending on the local AOD relative to the regional thresholds. Stringent aerosol pollution reductions motivated by public health concerns, especially in the North China Plain and

  14. Carbon Isotopes in Ocean and Land Carbon Cycle Models: Atmospheric Forcing Data and Applications for CMIP6 and Beyond

    Science.gov (United States)

    Graven, H. D.; Allison, C. E.; Etheridge, D. M.; Hammer, S.; Keeling, R. F.; Krummel, P. B.; Langenfelds, R. L.; Levin, I.; Rubino, M.; Trudinger, C. M.; Vaughn, B. H.; White, J. W. C.

    2016-12-01

    The carbon isotopic composition of ocean and land carbon reservoirs is influenced by fossil fuel burning, carbon residence time, and fractionation associated with biological and physical processes. Additionally, 14C produced during nuclear weapons testing in the 1950s and 60s has enriched 14C/C ratios in decadally overturning reservoirs. Comparisons of simulated 14C and 13C dynamics between models and with observations can provide insights to key processes in the global carbon cycle including air-sea gas exchange, ocean mixing, terrestrial drought response, and vegetation and soil carbon turnover rates. However, the inclusion of carbon isotopes in large-scale model intercomparisons has so far been limited. One study, the Ocean Carbon Cycle Model Intercomparison Project 2 (OCMIP2), used simulations of ocean 14C to identify biases in model ocean circulation that affect simulated anthropogenic CO2 uptake and marine biogeochemistry. Within the context of CMIP6, we are working to advance the use of carbon isotopes for carbon cycle science, model evaluation and model intercomparison. The variables requested for DECK, OMIP and C4MIP simulations in CMIP6 include stocks and fluxes of 14C and 13C (for models that simulate 14C and 13C). We will present the historical and future atmospheric forcing datasets for Δ14C and δ13C in CO2 that we are making available to modeling groups as part of CMIP6. The historical data uses atmospheric measurements and ice core and tree ring records. For future atmospheric forcing, we use a simple carbon cycle model with CO2 emissions and atmospheric CO2 concentration for different scenarios from ScenarioMIP. We will also describe potential applications for carbon isotope simulations from CMIP6 or other modeling activities. In particular, we will present an evaluation of terrestrial carbon turnover with simulations of bomb-derived 14C inventories in simplified off-line models based on carbon stocks and fluxes in CMIP5 terrestrial models.

  15. Dynamics of Blue Carbon Stocks and GHG Emissions Along a Land Use Gradient in El Salvador

    Science.gov (United States)

    Cifuentes, M.; Torres, D.; Sergio, V.; Rivera, C. G.; Molina, O.

    2016-12-01

    Coastal blue carbon ecosystems can store up to 5 times more carbon than their terrestrial counterparts. The former are also under great threats stemming from climate change (i.e. sea level rise) and human encroachment (i.e. land use change). Our research was conducted in Jiquilisco and Jaltepeque Bays in El Salvador and constitutes the first-ever assessment of blue carbon stocks and GHG emissions along a land use gradient in the country. Ecosystem-level carbon stocks were measured in mangroves (natural and restored stands), marshes, shrimp farms, artisan salt flats, and adjacent agriculture areas. Ecosystem carbon ranged from 738 ± 116 MgC·ha-1 to 617 ± 115 MgC·ha-1 in tall and medium mangroves to 191 ± 28 MgC·ha-1 in dwarf mangroves. An average 87 % of this carbon is sequestered in the soil, consistent with measurements made elsewhere. Carbon losses from conversion from mangroves to agricultural uses reduced natural stocks by 90%, thus producing dramatic historical emissions in the country. Conservative estimates suggest historical (1993-2014) carbon emissions from this land-use dynamics may amount to 48495 to 58004 Gg CO2e, representing 3 to 4 times the country's emissions in 2005. Our data allow us to test the efficacy of "Ecological Mangrove Restoration" programs promoted in El Salvador to strengthen local governance, livelihoods and ecosystem stability. Restored mangrove stands represent anywhere from 36 to 77 % of ecosystem carbon stocks measured in natural stands, suggesting they are playing an important role in recovering lost stocks over time. Further efforts should be spent in expanding community mangrove restoration, and ensuring carbon sequestration is properly included in the national MRV system for REDD+.

  16. How do soil properties and soil carbon stocks change after land abandonment in Mediterranean mountain areas?

    Science.gov (United States)

    Nadal Romero, Estela; Cammeraat, Erik; Pérez Cardiel, Estela; Lasanta, Teodoro

    2016-04-01

    Land abandonment and subsequent revegetation processes (due to secondary succession and afforestation practices) are global issues with important implications in Mediterranean mountain areas. Moreover, the effects of land use changes on soil carbon stocks are a matter of concern stated in international policy agendas on the mitigation of greenhouse emissions, and afforestation practices are increasingly viewed as an environmental restorative land use change prescription and are considered one of the most efficient carbon sequestration strategies currently available. The MED-AFFOREST project aims to gain more insight into the discussion by exploring the following central research questions: (i) what is the impact of land abandonment on soil properties? and (ii) how do soil organic carbon change after land abandonment? The main objective of this study is to assess the effects of land abandonment, land use change and afforestation practices on soil properties and soil organic carbon (SOC) dynamics. For this aim, five different land covers (bare soil, meadows, secondary succession, Pinus sylvestris (PS) and Pinus nigra (PN) afforestation), in the Central Spanish Pyrenees were analysed. Results showed that changes in soil properties after land abandonment were limited, even if afforestation practices were carried out and no differences were observed between natural succession and afforestation. The results on SOC dynamics showed that: (i) SOC contents were higher in the PN sites in the topsoil (10 cm), (ii) when all the profile was considered no significant differences were observed between meadows and PN, (iii) SOC accumulation under secondary succession is a slow process, and (iv) meadows should also be considered due to the relative importance in SOC stocks. The first step of SOC stabilization after afforestation is the formation of macro-aggregates promoted by large inputs of SOC, with a high contribution of labile organic matter. However, our respiration

  17. Indirect land-use changes can overcome carbon savings from biofuels in Brazil.

    Science.gov (United States)

    Lapola, David M; Schaldach, Ruediger; Alcamo, Joseph; Bondeau, Alberte; Koch, Jennifer; Koelking, Christina; Priess, Joerg A

    2010-02-23

    The planned expansion of biofuel plantations in Brazil could potentially cause both direct and indirect land-use changes (e.g., biofuel plantations replace rangelands, which replace forests). In this study, we use a spatially explicit model to project land-use changes caused by that expansion in 2020, assuming that ethanol (biodiesel) production increases by 35 (4) x 10(9) liter in the 2003-2020 period. Our simulations show that direct land-use changes will have a small impact on carbon emissions because most biofuel plantations would replace rangeland areas. However, indirect land-use changes, especially those pushing the rangeland frontier into the Amazonian forests, could offset the carbon savings from biofuels. Sugarcane ethanol and soybean biodiesel each contribute to nearly half of the projected indirect deforestation of 121,970 km(2) by 2020, creating a carbon debt that would take about 250 years to be repaid using these biofuels instead of fossil fuels. We also tested different crops that could serve as feedstock to fulfill Brazil's biodiesel demand and found that oil palm would cause the least land-use changes and associated carbon debt. The modeled livestock density increases by 0.09 head per hectare. But a higher increase of 0.13 head per hectare in the average livestock density throughout the country could avoid the indirect land-use changes caused by biofuels (even with soybean as the biodiesel feedstock), while still fulfilling all food and bioenergy demands. We suggest that a closer collaboration or strengthened institutional link between the biofuel and cattle-ranching sectors in the coming years is crucial for effective carbon savings from biofuels in Brazil.

  18. Indirect land-use changes can overcome carbon savings from biofuels in Brazil

    Science.gov (United States)

    Lapola, David M.; Schaldach, Ruediger; Alcamo, Joseph; Bondeau, Alberte; Koch, Jennifer; Koelking, Christina; Priess, Joerg A.

    2010-01-01

    The planned expansion of biofuel plantations in Brazil could potentially cause both direct and indirect land-use changes (e.g., biofuel plantations replace rangelands, which replace forests). In this study, we use a spatially explicit model to project land-use changes caused by that expansion in 2020, assuming that ethanol (biodiesel) production increases by 35 (4) x 109 liter in the 2003-2020 period. Our simulations show that direct land-use changes will have a small impact on carbon emissions because most biofuel plantations would replace rangeland areas. However, indirect land-use changes, especially those pushing the rangeland frontier into the Amazonian forests, could offset the carbon savings from biofuels. Sugarcane ethanol and soybean biodiesel each contribute to nearly half of the projected indirect deforestation of 121,970 km2 by 2020, creating a carbon debt that would take about 250 years to be repaid using these biofuels instead of fossil fuels. We also tested different crops that could serve as feedstock to fulfill Brazil’s biodiesel demand and found that oil palm would cause the least land-use changes and associated carbon debt. The modeled livestock density increases by 0.09 head per hectare. But a higher increase of 0.13 head per hectare in the average livestock density throughout the country could avoid the indirect land-use changes caused by biofuels (even with soybean as the biodiesel feedstock), while still fulfilling all food and bioenergy demands. We suggest that a closer collaboration or strengthened institutional link between the biofuel and cattle-ranching sectors in the coming years is crucial for effective carbon savings from biofuels in Brazil. PMID:20142492

  19. Global land carbon sink response to temperature and precipitation varies with ENSO phase

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Yuanyuan [Carnegie Inst. of Science, Stanford, CA (United States); Michalak, Anna M. [Carnegie Inst. of Science, Stanford, CA (United States); Schwalm, Christopher R. [Woods Hole Research Center, Falmouth, MA (United States); Huntzinger, Deborah N. [Northern Arizona Univ., Flagstaff, AZ (United States); Berry, Joseph A. [Carnegie Inst. of Science, Stanford, CA (United States); Ciais, Philippe [Alternative Energies and Atomic Energy Commission (CEA), Gif sur Yvette (France); Piao, Shilong [Peking Univ., Beijing (China); Poulter, Benjamin [Montana State Univ., Bozeman, MT (United States); Fisher, Joshua B. [California Inst. of Technology (CalTech), Pasadena, CA (United States); Cook, Robert B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hayes, Daniel [Univ. of Maine, Orno, ME (United States); Huang, Maoyi [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ito, Akihiko [National Inst. for Environmental Studies, Tsukuba (Japan); Jain, Atul [Univ. of Illinois, Urbana-Champaign, IL (United States); Lei, Huimin [Tsinghua Univ., Beijing (China); Lu, Chaoqun [Ames Lab. and Iowa State Univ., Ames, IA (United States); Mao, Jiafu [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Parazoo, Nicholas C. [California Inst. of Technology (CalTech), Pasadena, CA (United States); Peng, Shushi [Peking Univ., Beijing (China); Ricciuto, Daniel M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shi, Xiaoying [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tao, Bo [Univ. of Kentucky, Lexington, KY (United States); Tian, Hanqin [Auburn Univ., AL (United States); Wang, Weile [NASA Ames Research Center (ARC), Moffett Field, Mountain View, CA (United States); Wei, Yaxing [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yang, Jia [Auburn Univ., AL (United States)

    2017-06-01

    Climate variability associated with the El Niño-Southern Oscillation (ENSO) and its consequent impacts on land carbon sink interannual variability have been used as a basis for investigating carbon cycle responses to climate variability more broadly, and to inform the sensitivity of the tropical carbon budget to climate change. Past studies have presented opposing views about whether temperature or precipitation is the primary factor driving the response of the land carbon sink to ENSO. We show that the dominant driver varies with ENSO phase. And whereas tropical temperature explains sink dynamics following El Niño conditions (r TG,P = 0.59, p < 0.01), the post La Niña sink is driven largely by tropical precipitation (r PG,T= -0.46, p = 0.04). This finding points to an ENSO-phase-dependent interplay between water availability and temperature in controlling the carbon uptake response to climate variations in tropical ecosystems. Furthermore, we find that none of a suite of ten contemporary terrestrial biosphere models captures these ENSO-phase-dependent responses, highlighting a key uncertainty in modeling climate impacts on the future of the global land carbon sink.

  20. [Soil organic carbon storage changes with land reclamation under vegetation reconstruction on opencast coal mine dump].

    Science.gov (United States)

    Li, Jun-Chao; Dang, Ting-Hui; Guo, Sheng-Li; Xue, Jiang; Tang, Jun

    2014-10-01

    Vegetation reconstruction was an effective solution to reclaim the opencast coal mine dump which was formed in the process of mining. To understand the impact of the vegetation reconstruction patterns' on the mine soil organic carbon (SOC) storage was essential for selecting the methods of vegetation restoration and also important for accurately estimating the potential of the soil carbon sequestration. The study area was on the Heidaigou opencast coal mine, which was 15 years reclaimed coal mine dump in Zhungeer, Inner Mongolia autonomous region, we selected 5 vegetation reconstruction patterns (natural recovery land, grassland, bush land, mixed woodland of arbor and bush, arbor land), and 16 vegetation types, 408 soil samples (0-100 m), to study the effect of the vegetation reconstruction patterns on the SOC storage. The results were showed as follows: (1) on the reclaimed coal mine dump, the vegetation reconstruction patterns significantly affected the SOC content and its distribution in the soil profile (P shrub land > arbor forest > mixed forest of arbor and shrub > natural recovery land, in which the grassland, shrub land and arbor forest were about 2.2, 1.3, and 1.3 times of natural recovery land (2.14 g · kg(-1)) respectively. The total nitrogen (TN) showed the similar trends. (2) Among the vegetation types, Medicago sativa had the highest surface SOC content (5.71 g · kg(-1)) and TN content (0.49 g · kg(-1)), that were 171.3% and 166.7% higher than the natural recovery land, and two times of Hippophae rhamnoides, Amorpha fruticosa + Pinus tabulaeformis and Robinia pseudoacacia. (3) The effect of vegetation types on SOC mainly concentrated in the 0-20 cm depth, and the effect on TN accounted for 40 cm. (4) For the SOC storage, the order was original landform area > reclaimed dump > new dump and grassland > woodland (including arbor and shrub land). After 15 years revegetation, the soil carbon storage of the grassland, shrub land and arbor land were

  1. The role of protected areas in land use/land cover change and the carbon cycle in the conterminous United States.

    Science.gov (United States)

    Lu, Xiaoliang; Zhou, Yuyu; Liu, Yaling; Le Page, Yannick

    2017-07-16

    Protected areas (PAs) cover about 22% of the conterminous United States. Understanding their role on historical land use and land cover change (LULCC) and on the carbon cycle is essential to provide guidance for environmental policies. In this study, we compiled historical LULCC and PAs data to explore these interactions within the terrestrial ecosystem model (TEM). We found that intensive LULCC occurred in the conterminous United States from 1700 to 2005. More than 3 million km(2) of forest, grassland and shrublands were converted into agricultural lands, which caused 10,607 Tg C release from land ecosystems to atmosphere. PAs had experienced little LULCC as they were generally established in the 20th century after most of the agricultural expansion had occurred. PAs initially acted as a carbon source due to land use legacies, but their accumulated carbon budget switched to a carbon sink in the 1960s, sequestering an estimated 1,642 Tg C over 1700-2005, or 13.4% of carbon losses in non-PAs. We also find that PAs maintain larger carbon stocks and continue sequestering carbon in recent years (2001-2005), but at a lower rate due to increased heterotrophic respiration as well as lower productivity associated to aging ecosystems. It is essential to continue efforts to maintain resilient, biodiverse ecosystems and avoid large-scale disturbances that would release large amounts of carbon in PAs. © 2017 John Wiley & Sons Ltd.

  2. Acetaldehyde stimulation of net gluconeogenic carbon movement from applied malic acid in tomato fruit pericarp tissue

    Energy Technology Data Exchange (ETDEWEB)

    Halinska, A.; Frenkel, C. (Rutgers, The State Univ. of New Jersey, New Brunswick (United States))

    1991-03-01

    Applied acetaldehyde is known to lead to sugar accumulation in fruit including tomatoes (Lycopersicon esculentum) presumably due to stimulation of gluconeogenesis. This conjecture was examined using tomato fruit pericarp discs as a test system and applied l-(U-{sup 14}C)malic acid as the source for gluconeogenic carbon mobilization. Results indicate that malic and perhaps other organic acids are carbon sources for gluconeogenesis occurring normally in ripening tomatoes. The process is stimulated by acetaldehyde apparently by attenuating the fructose-2,6-biphosphate levels. The mode of the acetaldehyde regulation of fructose-2,6-biphosphate metabolism awaits clarification.

  3. Difference Analysis of Different Land Use Types on Soil Organic Carbon in Loess Gullied-Hilly Region of China

    Directory of Open Access Journals (Sweden)

    Jianing Zhang

    2015-02-01

    Full Text Available The cycles of carbon in terrestrial ecosystems has received increasing attention worldwide. Because the balance between inputs and outputs of carbon to the soil has an important influences on the atmospheric CO2 and global climate. With the increasing deforestation and overgrazing, the impact of human disturbances on carbon storage and fluxes have exceeded the rate and extent of effects from natural variability, this could significantly raise the CO2 concentration in the atmosphere. Thus, accurate estimations of land use and land cover in soil ecosystem have become increasingly important for estimating the carbon balance of regions. One of the greatest uncertainties concerning the influence of human activities is changes in soil carbon stock. In this study, soil samples were collected form farmland, orchard, woodland, grassland, wasteland five different land use types. Each soil sample core was separated into 0-10, 10-20, 20-40 and 40-60 cm depth. The study revealed the difference of soil carbon pool storage and mass effect in different land use styles by the contrast analysis of total organic carbon, labile organic carbon and carbon management index in number, distribution and changes. The results showed that there were big differences for the density of Total Organic Carbon (TOC among different land use types, which means soil organic carbon storages were different. The extent of variation of the mass fraction of TOC and LOC was increase with the increase of soil depth and 0-20 cm layer was significantly greater than 20-60 cm layer. Relative to wasteland, the density of LOC and NLOC, total organic carbon storage and carbon management index for other four land use types were higher, especial for woodland and grassland. The woodland use type and grassland use type were significantly increased the carbon management index and improved the quality of soil carbon pool. The change of soil organic carbon reserve is huge influenced by human land use.

  4. Constraining a land-surface model with multiple observations by application of the MPI-Carbon Cycle Data Assimilation System V1.0

    Science.gov (United States)

    Schürmann, Gregor J.; Kaminski, Thomas; Köstler, Christoph; Carvalhais, Nuno; Voßbeck, Michael; Kattge, Jens; Giering, Ralf; Rödenbeck, Christian; Heimann, Martin; Zaehle, Sönke

    2016-09-01

    We describe the Max Planck Institute Carbon Cycle Data Assimilation System (MPI-CCDAS) built around the tangent-linear version of the JSBACH land-surface scheme, which is part of the MPI-Earth System Model v1. The simulated phenology and net land carbon balance were constrained by globally distributed observations of the fraction of absorbed photosynthetically active radiation (FAPAR, using the TIP-FAPAR product) and atmospheric CO2 at a global set of monitoring stations for the years 2005 to 2009. When constrained by FAPAR observations alone, the system successfully, and computationally efficiently, improved simulated growing-season average FAPAR, as well as its seasonality in the northern extra-tropics. When constrained by atmospheric CO2 observations alone, global net and gross carbon fluxes were improved, despite a tendency of the system to underestimate tropical productivity. Assimilating both data streams jointly allowed the MPI-CCDAS to match both observations (TIP-FAPAR and atmospheric CO2) equally well as the single data stream assimilation cases, thereby increasing the overall appropriateness of the simulated biosphere dynamics and underlying parameter values. Our study thus demonstrates the value of multiple-data-stream assimilation for the simulation of terrestrial biosphere dynamics. It further highlights the potential role of remote sensing data, here the TIP-FAPAR product, in stabilising the strongly underdetermined atmospheric inversion problem posed by atmospheric transport and CO2 observations alone. Notwithstanding these advances, the constraint of the observations on regional gross and net CO2 flux patterns on the MPI-CCDAS is limited through the coarse-scale parametrisation of the biosphere model. We expect improvement through a refined initialisation strategy and inclusion of further biosphere observations as constraints.

  5. Carbon, Climate, and Land-use in Ukraine: Forest Sector

    OpenAIRE

    Shvidenko, A.; P. Lakyda; Schepaschenko, D; R. Vasylyshyn; Machuk, Y.

    2014-01-01

    Stabilization of climate and maintenance of ecological stability over the planet within the paradigm of sustainable development underline the role of forests as one of the most effective and appropriate tools for climate change mitigation. This publication attempts to provide a system analysis of carbon budget of Ukrainian forests using internationally examined methods, as well as to analyze the impacts of the forests on climatic change within two potential scenarios of future forest manageme...

  6. Carbon Calculator for Land Use Change from Biofuels Production (CCLUB). Users' Manual and Technical Documentation

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, Jennifer B. [Argonne National Lab. (ANL), Argonne, IL (United States); Qin, Zhangcai [Argonne National Lab. (ANL), Argonne, IL (United States); Mueller, Steffen [Univ. of Illinois at Chicago, Chicago, IL (United States); Kwon, Ho-young [International Food Policy Research Institute (IFPRI), Washington, DC (United States); Wander, Michelle M. [Univ. of Illinois, Urbana-Champaign, IL (United States); Wang, Michael [Argonne National Lab. (ANL), Argonne, IL (United States)

    2014-09-01

    The Carbon Calculator for Land Use Change from Biofuels Production (CCLUB) calculates carbon emissions from land use change (LUC) for four different ethanol production pathways including corn grain ethanol and cellulosic ethanol from corn stover, Miscanthus, and switchgrass. This document discusses the version of CCLUB released September 30, 2014 which includes corn and three cellulosic feedstocks: corn stover, Miscanthus, and switchgrass.

  7. Assessment of soil organic carbon stocks under future climate and land cover changes in Europe.

    Science.gov (United States)

    Yigini, Yusuf; Panagos, Panos

    2016-07-01

    Soil organic carbon plays an important role in the carbon cycling of terrestrial ecosystems, variations in soil organic carbon stocks are very important for the ecosystem. In this study, a geostatistical model was used for predicting current and future soil organic carbon (SOC) stocks in Europe. The first phase of the study predicts current soil organic carbon content by using stepwise multiple linear regression and ordinary kriging and the second phase of the study projects the soil organic carbon to the near future (2050) by using a set of environmental predictors. We demonstrate here an approach to predict present and future soil organic carbon stocks by using climate, land cover, terrain and soil data and their projections. The covariates were selected for their role in the carbon cycle and their availability for the future model. The regression-kriging as a base model is predicting current SOC stocks in Europe by using a set of covariates and dense SOC measurements coming from LUCAS Soil Database. The base model delivers coefficients for each of the covariates to the future model. The overall model produced soil organic carbon maps which reflect the present and the future predictions (2050) based on climate and land cover projections. The data of the present climate conditions (long-term average (1950-2000)) and the future projections for 2050 were obtained from WorldClim data portal. The future climate projections are the recent climate projections mentioned in the Fifth Assessment IPCC report. These projections were extracted from the global climate models (GCMs) for four representative concentration pathways (RCPs). The results suggest an overall increase in SOC stocks by 2050 in Europe (EU26) under all climate and land cover scenarios, but the extent of the increase varies between the climate model and emissions scenarios.

  8. Longer growing seasons do not increase net carbon uptake in Northeastern Siberian tundra

    NARCIS (Netherlands)

    Parmentier, F.J.W.; Molen, van der M.K.; Huissteden, van J.; Karsanaev, S.; Kononov, A.V.; Suzdalov, D.; Maximov, T.C.; Dolman, A.J.

    2011-01-01

    With global warming, snowmelt is occurring earlier and growing seasons are becoming longer around the Arctic. It has been suggested that this would lead to more uptake of carbon due to a lengthening of the period in which plants photosynthesize. To investigate this suggestion, 8 consecutive years of

  9. Beyond pure offsetting: Assessing options to generate Net-Mitigation-Effects in carbon market mechanisms

    NARCIS (Netherlands)

    Warnecke, C.; Wartmann, S.; Hoehne, N.E.; Blok, K.

    2014-01-01

    The current project-based carbon market mechanisms such as the Clean Development Mechanism (CDM) and the Joint Implementation (JI) do not have a direct impact on global greenhouse gas emission levels, because they only replace or offset emissions. Nor do they contribute to host country¿s national gr

  10. Beyond pure offsetting: Assessing options to generate Net-Mitigation-Effects in carbon market mechanisms

    NARCIS (Netherlands)

    Warnecke, C.; Wartmann, S.; Hohne, N.; Blok, Kornelis

    2014-01-01

    The current project-based carbon market mechanisms such as the Clean Development Mechanism (CDM) and the Joint Implementation (JI) do not have a direct impact on global greenhouse gas emission levels, because they only replace or offset emissions. Nor do they contribute to host country׳s national gr

  11. Carbon cost of plant nitrogen acquisition: global carbon cycle impact from an improved plant nitrogen cycle in the Community Land Model.

    Science.gov (United States)

    Shi, Mingjie; Fisher, Joshua B; Brzostek, Edward R; Phillips, Richard P

    2016-03-01

    Plants typically expend a significant portion of their available carbon (C) on nutrient acquisition - C that could otherwise support growth. However, given that most global terrestrial biosphere models (TBMs) do not include the C cost of nutrient acquisition, these models fail to represent current and future constraints to the land C sink. Here, we integrated a plant productivity-optimized nutrient acquisition model - the Fixation and Uptake of Nitrogen Model - into one of the most widely used TBMs, the Community Land Model. Global plant nitrogen (N) uptake is dynamically simulated in the coupled model based on the C costs of N acquisition from mycorrhizal roots, nonmycorrhizal roots, N-fixing microbes, and retranslocation (from senescing leaves). We find that at the global scale, plants spend 2.4 Pg C yr(-1) to acquire 1.0 Pg N yr(-1) , and that the C cost of N acquisition leads to a downregulation of global net primary production (NPP) by 13%. Mycorrhizal uptake represented the dominant pathway by which N is acquired, accounting for ~66% of the N uptake by plants. Notably, roots associating with arbuscular mycorrhizal (AM) fungi - generally considered for their role in phosphorus (P) acquisition - are estimated to be the primary source of global plant N uptake owing to the dominance of AM-associated plants in mid- and low-latitude biomes. Overall, our coupled model improves the representations of NPP downregulation globally and generates spatially explicit patterns of belowground C allocation, soil N uptake, and N retranslocation at the global scale. Such model improvements are critical for predicting how plant responses to altered N availability (owing to N deposition, rising atmospheric CO2 , and warming temperatures) may impact the land C sink.

  12. Asymmetric warming significantly affects net primary production, but not ecosystem carbon balances of forest and grassland ecosystems in northern China.

    Science.gov (United States)

    Su, Hongxin; Feng, Jinchao; Axmacher, Jan C; Sang, Weiguo

    2015-03-13

    We combine the process-based ecosystem model (Biome-BGC) with climate change-scenarios based on both RegCM3 model outputs and historic observed trends to quantify differential effects of symmetric and asymmetric warming on ecosystem net primary productivity (NPP), heterotrophic respiration (Rh) and net ecosystem productivity (NEP) of six ecosystem types representing different climatic zones of northern China. Analysis of covariance shows that NPP is significant greater at most ecosystems under the various environmental change scenarios once temperature asymmetries are taken into consideration. However, these differences do not lead to significant differences in NEP, which indicates that asymmetry in climate change does not result in significant alterations of the overall carbon balance in the dominating forest or grassland ecosystems. Overall, NPP, Rh and NEP are regulated by highly interrelated effects of increases in temperature and atmospheric CO2 concentrations and precipitation changes, while the magnitude of these effects strongly varies across the six sites. Further studies underpinned by suitable experiments are nonetheless required to further improve the performance of ecosystem models and confirm the validity of these model predictions. This is crucial for a sound understanding of the mechanisms controlling the variability in asymmetric warming effects on ecosystem structure and functioning.

  13. Simulating crop phenology in the Community Land Model and its impact on energy and carbon fluxes

    Science.gov (United States)

    A reasonable representation of crop phenology and biophysical processes in land surface models is necessary to accurately simulate energy, water and carbon budgets at the field, regional, and global scales. However, the evaluation of crop models that can be coupled to earth system models is relative...

  14. Tropical Africa: Land Use, Biomass, and Carbon Estimates for 1980 (NDP-055)

    Energy Technology Data Exchange (ETDEWEB)

    Brown, S.

    2002-04-16

    This document describes the contents of a digital database containing maximum potential aboveground biomass, land use, and estimated biomass and carbon data for 1980. The biomass data and carbon estimates are associated with woody vegetation in Tropical Africa. These data were collected to reduce the uncertainty associated with estimating historical releases of carbon from land use change. Tropical Africa is defined here as encompassing 22.7 x 10{sup 6} km{sup 2} of the earth's land surface and is comprised of countries that are located in tropical Africa (Angola, Botswana, Burundi, Cameroon, Cape Verde, Central African Republic, Chad, Congo, Benin, Equatorial Guinea, Ethiopia, Djibouti, Gabon, Gambia, Ghana, Guinea, Ivory Coast, Kenya, Liberia, Madagascar, Malawi, Mali, Mauritania, Mozambique, Namibia, Niger, Nigeria, Guinea-Bissau, Zimbabwe (Rhodesia), Rwanda, Senegal, Sierra Leone, Somalia, Sudan, Tanzania, Togo, Uganda, Burkina Faso (Upper Volta), Zaire, and Zambia). The database was developed using the GRID module in the ARC/INFO{trademark} geographic information system. Source data were obtained from the Food and Agriculture Organization (FAO), the U.S. National Geophysical Data Center, and a limited number of biomass-carbon density case studies. These data were used to derive the maximum potential and actual (ca. 1980) aboveground biomass values at regional and country levels. The land-use data provided were derived from a vegetation map originally produced for the FAO by the International Institute of Vegetation Mapping, Toulouse, France.

  15. Linking carbon stock change from land-use change to consumption of agricultural products: Alternative perspectives

    NARCIS (Netherlands)

    Goh, Chun Sheng; Wicke, Birka; Faaij, André; Bird, David Neil; Schwaiger, Hannes; Junginger, Martin

    2016-01-01

    Abstract Agricultural expansion driven by growing demand has been a key driver for carbon stock change as a consequence of land-use change (CSC-LUC). However, its relative role compared to non-agricultural and non-productive drivers, as well as propagating effects were not clearly addressed. This st

  16. Net carbon sequestration potential and emissions in home lawn turfgrasses of the United States.

    Science.gov (United States)

    Selhorst, Adam; Lal, Rattan

    2013-01-01

    Soil analyses were conducted on home lawns across diverse ecoregions of the U.S. to determine the soil organic carbon (SOC) sink capacity of turfgrass soils. Establishment of lawns sequestered SOC over time. Due to variations in ecoregions, sequestration rates varied among sites from 0.9 Mg carbon (C) ha(-1) year(-1) to 5.4 Mg C ha(-1) year(-1). Potential SOC sink capacity also varied among sites ranging from 20.8 ± 1.0-96.3 ± 6.0 Mg C ha(-1). Average sequestration rate and sink capacity for all sites sampled were 2.8 ± 0.3 Mg C ha(-1) year(-1) and 45.8 ± 3.5 Mg C ha(-1), respectively. Additionally, the hidden carbon costs (HCC) due to lawn mowing (189.7 kg Ce (carbon equivalent) ha(-1) year(-1)) and fertilizer use (63.6 kg Ce ha(-1) year(-1)) for all sites totaled 254.3 kg Ce ha(-1) year(-1). Considering home lawn SOC sink capacity and HCC, mean home lawn sequestration was completely negated 184 years post establishment. The potential SOC sink capacity of home lawns in the U.S. was estimated at 496.3 Tg C, with HCC of between 2,504.1 Gg Ce year(-1) under low management regimes and 7551.4 Gg Ce year(-1) under high management. This leads to a carbon-positive system for between 66 and 199 years in U.S. home lawns. More efficient and reduction of C-intensive maintenance practices could increase the overall sequestration longevity of home lawns and improve their climate change mitigation potential.

  17. 78 FR 8188 - Notice of Realty Action: Proposed (Non-Competitive) Direct Sale of Public Land in Carbon County, UT

    Science.gov (United States)

    2013-02-05

    ... Bureau of Land Management Notice of Realty Action: Proposed (Non-Competitive) Direct Sale of Public Land.... SUMMARY: The Bureau of Land Management (BLM) is considering the (non- competitive) direct sale of 280... Carbon County, Utah, are proposed for direct sale, subject to the applicable provisions of Sections...

  18. Sensitivity analysis of the GEMS soil organic carbon model to land cover land use classification uncertainties under different climate scenarios in Senegal

    OpenAIRE

    A. M. Dieye; Roy, D.P.; N. P. Hanan; Liu, S.(State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China); Hansen, M.; Touré, A.

    2011-01-01

    Spatially explicit land cover land use (LCLU) change information is needed to drive biogeochemical models that simulate soil organic carbon (SOC) dynamics. Such information is increasingly being mapped using remotely sensed satellite data with classification schemes and uncertainties constrained by the sensing system, classification algorithms and land cover schemes. In this study, automated LCLU classification of multi-temporal Landsat satellite data were used to assess the sensitivity of SO...

  19. A spatial resolution threshold of land cover in estimating terrestrial carbon sequestration in four counties in Georgia and Alabama, USA

    Science.gov (United States)

    Zhao, S.Q.; Liu, S.; Li, Z.; Sohl, T.L.

    2010-01-01

    Changes in carbon density (i.e., carbon stock per unit area) and land cover greatly affect carbon sequestration. Previous studies have shown that land cover change detection strongly depends on spatial scale. However, the influence of the spatial resolution of land cover change information on the estimated terrestrial carbon sequestration is not known. Here, we quantified and evaluated the impact of land cover change databases at various spatial resolutions (250 m, 500 m, 1 km, 2 km, and 4 km) on the magnitude and spatial patterns of regional carbon sequestration in four counties in Georgia and Alabama using the General Ensemble biogeochemical Modeling System (GEMS). Results indicated a threshold of 1 km in the land cover change databases and in the estimated regional terrestrial carbon sequestration. Beyond this threshold, significant biases occurred in the estimation of terrestrial carbon sequestration, its interannual variability, and spatial patterns. In addition, the overriding impact of interannual climate variability on the temporal change of regional carbon sequestration was unrealistically overshadowed by the impact of land cover change beyond the threshold. The implications of these findings directly challenge current continental- to global-scale carbon modeling efforts relying on information at coarse spatial resolution without incorporating fine-scale land cover dynamics.

  20. Impact of cloudiness on net ecosystem exchange of carbon dioxide in different types of forest ecosystems in China

    Directory of Open Access Journals (Sweden)

    M. Zhang

    2010-02-01

    Full Text Available Clouds can significantly affect carbon exchange process between forest ecosystems and the atmosphere by influencing the quantity and quality of solar radiation received by ecosystem's surface and other environmental factors. In this study, we analyzed the effects of cloudiness on net ecosystem exchange of carbon dioxide (NEE in a temperate broad-leaved Korean pine mixed forest at Changbaishan (CBS and a subtropical evergreen broad-leaved forest at Dinghushan (DHS, based on the flux data obtained during June–August from 2003 to 2006. The results showed that the response of NEE of forest ecosystems to photosynthetically active radiation (PAR differed under clear skies and cloudy skies. Compared with clear skies, the light-saturated maximum photosynthetic rate (Pec,max at CBS under cloudy skies during mid-growing season (from June to August increased by 34%, 25%, 4% and 11% in 2003, 2004, 2005 and 2006, respectively. In contrast, Pec,max of the forest ecosystem at DHS was higher under clear skies than under cloudy skies from 2004 to 2006. When the clearness index (kt ranged between 0.4 and 0.6, the NEE reached its maximum at both CBS and DHS. However, the NEE decreased more dramatically at CBS than at DHS when kt exceeded 0.6. The results indicate that cloudy sky conditions are beneficial to net carbon uptake in the temperate forest ecosystem and the subtropical forest ecosystem. Under clear skies, vapor pressure deficit (VPD and air temperature increased due to strong light. These environmental conditions led to greater decrease in gross ecosystem photosynthesis (GEP and greater increase in ecosystem respiration (Re at CBS than at DHS. As a result, clear sky conditions caused more reduction of NEE in the temperate forest ecosystem than in the subtropical forest ecosystem. The response of NEE of different forest ecosystems to the changes in

  1. Carbon storage in soil and aggregates of Inceptisols under different land use management systems in southern Amazonas

    OpenAIRE

    Milton César Costa Campos; Marcelo Dayron Rodrigues Soares; Mailson Ferreira Nascimento; Douglas Marcelo Pinheiro Silva

    2016-01-01

    Land use and management systems are factors that can influence carbon stock and its aggregate stability. This study assessed the carbon stock and aggregate stability of Inceptisols under different land use and management systems. The study was conducted on five properties located in the southern region of Amazonas state. Five areas were selected with different traditional land use systems (agroforestry, cassava, sugarcane, pasture and native forest). On each site, grids of 50 m x 50 m, with r...

  2. Soil carbon sequestration and land use change associated with biofuel production: Empirical evidence

    Energy Technology Data Exchange (ETDEWEB)

    Qin, Zhangcai; Dunn, Jennifer B.; Kwon, Hoyoung; Mueller, Steffen; Wander, Michelle M.

    2016-01-01

    Soil organic carbon (SOC) change can be a major impact of land use change (LUC) associated with biofuel feedstock production. By collecting and analyzing data from worldwide field observations with major LUCs from cropland, grassland and forest to lands producing biofuel crops (i.e., corn, switchgrass, Miscanthus, poplar and willow), we were able to estimate SOC response ratios and sequestration rates and evaluate the effects of soil depth and time scale on SOC change. Both the amount and rate of SOC change were highly dependent on the specific land transition. Irrespective of soil depth or time horizon, cropland conversions resulted in an overall SOC gain of 6-14% relative to initial SOC level, while conversion from grassland or forest to corn (without residue removal) or poplar caused significant carbon loss (9-35%). No significant SOC changes were observed in land converted from grasslands or forests to switchgrass, Miscanthus or willow. The SOC response ratios were similar in both 0-30 and 0-100 cm soil depths in most cases, suggesting SOC changes in deep soil and that use of top soil only for SOC accounting in biofuel life cycle analysis (LCA) might underestimate total SOC changes. Soil carbon sequestration rates varied greatly among studies and land transition types. Generally, the rates of SOC change tended to be the greatest during the 10 years following land conversion, and had declined to approach 0 within about 20 years for most LUCs. Observed trends in SOC change were generally consistent with previous reports. Soil depth and duration of study significantly influence SOC change rates and so should be considered in carbon emission accounting in biofuel LCA. High uncertainty remains for many perennial systems, field trials and modeling efforts are needed to determine the site- and system-specific rates and direction of change associated with their production.

  3. Modelling carbon dynamics from urban land conversion: fundamental model of city in relation to a local carbon cycle

    Directory of Open Access Journals (Sweden)

    Schellnhuber Hans-Joachim

    2006-08-01

    Full Text Available Abstract Background The main task is to estimate the qualitative and quantitative contribution of urban territories and precisely of the process of urbanization to the Global Carbon Cycle (GCC. Note that, on the contrary to many investigations that have considered direct anthropogenic emission of CO2(urbanized territories produce ca. 96–98% of it, we are interested in more subtle, and up until the present time, weaker processes associated with the conversion of the surrounding natural ecosystems and landscapes into urban lands. Such conversion inevitably takes place when cities are sprawling and additional "natural" lands are becoming "urbanized". Results In order to fulfil this task, we first develop a fundamental model of urban space, since the type of land cover within a city makes a difference for a local carbon cycle. Hence, a city is sub-divided by built-up, „green" (parks, etc. and informal settlements (favelas fractions. Another aspect is a sub-division of the additional two regions, which makes the total number reaching eight regions, while the UN divides the world by six. Next, the basic model of the local carbon cycle for urbanized territories is built. We consider two processes: carbon emissions as a result of conversion of natural lands caused by urbanization; and the transformation of carbon flows by "urbanized" ecosystems; when carbon, accumulated by urban vegetation, is exported to the neighbouring territories. The total carbon flow in the model depends, in general, on two groups of parameters. The first includes the NPP, and the sum of living biomass and dead organic matter of ecosystems involved in the process of urbanization, and namely them we calculate here, using a new more realistic approach and taking into account the difference in regional cities' evolution. Conclusion There is also another group of parameters, dealing with the areas of urban territories, and their annual increments. A method of dynamic forecasting

  4. Impacts of land use/land cover change on regional carbon dynamics: an investigation along an urban-to-rural gradient in Massachusetts, USA

    Science.gov (United States)

    Dunn, Allison L.; Briber, Brittain M.; Reinmann, Andrew B.; Hutyra, Lucy R.

    2016-04-01

    More than half the world's population lives in cities, a fraction which is projected to increase over the next century. Land use and land cover changes associated with the urbanization process have important implications for vegetation and soil carbon cycling. The impact of urbanization on carbon dynamics is poorly understood, representing a major uncertainty in constraining regional carbon budgets. We initiated a suite of field measurements, remote sensing analyses, and modeling activities in order to investigate how urbanization alters carbon dynamics. We found that conversion of forest to urban land uses resulted in a decrease in overall biomass but a marked increase in productivity of the remaining vegetation. We also found that land use patterns had a profound impact on atmospheric carbon dioxide concentrations on daily, seasonal, and annual timescales. Our results suggest that urbanization has a profound impact on regional carbon dynamics that extends from the time of land use change out well into the future, and the trajectory of urban carbon exchange in the future strongly depends on development patterns.

  5. Temporal patterns of land-use change and carbon storage in China and tropical Asia

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Evaluating the annual sources and sinks of carbon from land-use changehelps constrain other terms in the global carbon cycle and may help countries choose how to comply with commitments for reduced emissions. This paper presents the results of recent analyses of land-use change in China and tropical Asia. The original forest areas are estimated to have covered 546×106 ha in tropical Asia and 425×106 ha in China. By 1850, 44% of China's forests had been cleared, and another 27% was lost between 1850 and 1980, leaving China with 13% forest cover (29% of the initial forest area). Tropical Asia is estimated to have lost 26%of its initial forest cover before 1850 and another 33% after 1850. The annual emissions of carbon from the two regions reflect the different histories over the last 150 years, with China's emissions peaking in the late 1950s (at 0.2-0.5 Pg C@a-1) and tropical Asia's emissions peaking in 1990s (at 1.0 Pg C@a-1). Despite the fact that most deforestation has been for new agricultural land, the majority of the lands cleared from forests in China are no longer croplands, but fallow or degraded shrublands. Unlike croplands, the origins of these other lands are poorly documented, and thus add considerable uncertainty to estimates of flux before the 1980s. Nevertheless, carbon emissions from China seem to have decreased since the 1960s to nearly zero at present. In contrast, emissions of carbon from tropical Asia were higher in the 1990s than that at any time in the past.

  6. Land-Based Mitigation Strategies under the Mid-Term Carbon Reduction Targets in Indonesia

    Directory of Open Access Journals (Sweden)

    Tomoko Hasegawa

    2016-12-01

    Full Text Available We investigated the key mitigation options for achieving the mid-term target for carbon emission reduction in Indonesia. A computable general equilibrium model coupled with a land-based mitigation technology model was used to evaluate specific mitigation options within the whole economic framework. The results revealed three primary findings: (1 If no climate policy were implemented, Indonesia’s total greenhouse gas emissions would reach 3.0 GtCO2eq by 2030; (2 To reduce carbon emissions to meet the latest Intended Nationally-Determined Contributions (INDC target, ~58% of total reductions should come from the agriculture, forestry and other land use sectors by implementing forest protection, afforestation and plantation efforts; (3 A higher carbon price in 2020 suggests that meeting the 2020 target would be economically challenging, whereas the INDC target for 2030 would be more economically realistic in Indonesia.

  7. Meeting the Demand for Biofuels: Impact on Land Use and Carbon Mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Khanna, Madhu; Jain, Atul; Onal, Hayri; Scheffran, Jurgen; Chen, Xiaoguang; Erickson, Matt; Huang, Haixiao; Kang, Seungmo.

    2011-08-14

    The purpose of this research was to develop an integrated, interdisciplinary framework to investigate the implications of large scale production of biofuels for land use, crop production, farm income and greenhouse gases. In particular, we examine the mix of feedstocks that would be viable for biofuel production and the spatial allocation of land required for producing these feedstocks at various gasoline and carbon emission prices as well as biofuel subsidy levels. The implication of interactions between energy policy that seeks energy independence from foreign oil and climate policy that seeks to mitigate greenhouse gas emissions for the optimal mix of biofuels and land use will also be investigated. This project contributes to the ELSI research goals of sustainable biofuel production while balancing competing demands for land and developing policy approaches needed to support biofuel production in a cost-effective and environmentally friendly manner.

  8. Understanding the Impact of Land Management on Carbon Losses from Peatlands

    Science.gov (United States)

    Savage, A.; Holden, J.; Wainwright, J.

    2010-05-01

    British peatlands have historically been managed in many different ways to provide an income for rural communities. Such practices involve heather burning on grouse shooting estates, sheep grazing, drainage to increase the area of land available for agriculture and afforestation. Carbon budget calculations for unmanaged peatlands have demonstrated that peatlands are carbon sinks. At present, little is known about how management affects carbon stocks, and whether one strategy might be favoured over another in the future, from a carbon stock preservation perspective. As the need to safeguard carbon stocks rises up the political agenda, questions are being asked about how peatlands should be managed to limit carbon losses. Carbon cycling in peat is governed by four drivers (Laiho, 2006), environmental conditions (e.g. temperature, water table level), substrate quality (e.g. how recalcitrant the peat is), nutrients (e.g. nitrogen required to synthesis the carbon stocks) and microbial community (e.g. are the microbes present able to utilise the available substrate). Changes in one or more of these drivers will influence the carbon budget of a peatland. How land management influences these drivers is unclear at present. Carbon budget calculations carried out by Worrall et al. (2003 and 2009) indicate that carbon dioxide and dissolved organic carbon (DOC) account for the greatest losses of carbon from peatland systems. If climate change predictions are realised, peatlands are expected to become sources of carbon as rising temperatures and falling water tables will result in increased rates of carbon mineralisation and subsequent losses of carbon. By investigating the influence of land management on these key carbon loss pathways, more accurate predictions of the effects of climate change on UK peatlands can be made. A field study was carried out in the British uplands to determine how carbon losses vary between differently managed peatlands, and to identify some of the

  9. Effects of rodent-induced land degradation on ecosystem carbon fluxes in an alpine meadow in the Qinghai-Tibet Plateau, China

    Science.gov (United States)

    Peng, F.; Quangang, Y.; Xue, X.; Guo, J.; Wang, T.

    2015-03-01

    The widespread land degradation in an alpine meadow ecosystem would affect ecosystem carbon (C) balance. Biomass, soil chemical properties and carbon dioxide (CO2) of six levels of degraded lands (D1-D6, according to the number of rodent holes and coverage) were investigated to examine the effects of rodent-induced land degradation on an alpine meadow ecosystem. Soil organic carbon (SOC), labile soil carbon (LC), total nitrogen (TN) and inorganic nitrogen (N) were obtained by chemical analysis. Soil respiration (Rs), net ecosystem exchange (NEE) and ecosystem respiration (ER) were measured by a Li-Cor 6400XT. Gross ecosystem production (GEP) was the sum of NEE and ER. Aboveground biomass (AGB) was based on a linear regression with coverage and plant height as independent variables. Root biomass (RB) was obtained by using a core method. Soil respiration, ER, GEP and AGB were significantly higher in slightly degraded (D3 and D6, group I) than in severely degraded land (D1, D2, D4 and D5, group II). Positive values of NEE average indicate that the alpine meadow ecosystem is a weak C sink during the growing season. The only significant difference was in ER among different degradation levels. Rs, ER and GEP were 38.2, 44.3 and 46.5% higher in group I than in group II, respectively. Similar difference of ER and GEP between the two groups resulted in an insignificant difference of NEE. Positive correlations of AGB with ER, NEE and GEP, and relatively small AGB and lower CO2 fluxes in group II, suggest the control of AGB on ecosystem CO2 fluxes. Correlations of RB with SOC, LC, TN and inorganic N indicate the regulation of RB on soil C and N with increasing number of rodent holes in an alpine meadow ecosystem in the permafrost region of the Qinghai-Tibet Plateau (QTP).

  10. Implications of land use change on the national terrestrial carbon budget of Georgia

    Directory of Open Access Journals (Sweden)

    Olofsson Pontus

    2010-09-01

    Full Text Available Abstract Background Globally, the loss of forests now contributes almost 20% of carbon dioxide emissions to the atmosphere. There is an immediate need to reduce the current rates of forest loss, and the associated release of carbon dioxide, but for many areas of the world these rates are largely unknown. The Soviet Union contained a substantial part of the world's forests and the fate of those forests and their effect on carbon dynamics remain unknown for many areas of the former Eastern Bloc. For Georgia, the political and economic transitions following independence in 1991 have been dramatic. In this paper we quantify rates of land use changes and their effect on the terrestrial carbon budget for Georgia. A carbon book-keeping model traces changes in carbon stocks using historical and current rates of land use change. Landsat satellite images acquired circa 1990 and 2000 were analyzed to detect changes in forest cover since 1990. Results The remote sensing analysis showed that a modest forest loss occurred, with approximately 0.8% of the forest cover having disappeared after 1990. Nevertheless, growth of Georgian forests still contribute a current national sink of about 0.3 Tg of carbon per year, which corresponds to 31% of the country anthropogenic carbon emissions. Conclusions We assume that the observed forest loss is mainly a result of illegal logging, but we have not found any evidence of large-scale clear-cutting. Instead local harvesting of timber for household use is likely to be the underlying driver of the observed logging. The Georgian forests are a currently a carbon sink and will remain as such until about 2040 if the current rate of deforestation persists. Forest protection efforts, combined with economic growth, are essential for reducing the rate of deforestation and protecting the carbon sink provided by Georgian forests.

  11. Thermal optimality of net ecosystem exchange of carbon dioxide and underlying mechanisms.

    Science.gov (United States)

    Niu, Shuli; Luo, Yiqi; Fei, Shenfeng; Yuan, Wenping; Schimel, David; Law, Beverly E; Ammann, Christof; Arain, M Altaf; Arneth, Almut; Aubinet, Marc; Barr, Alan; Beringer, Jason; Bernhofer, Christian; Black, T Andrew; Buchmann, Nina; Cescatti, Alessandro; Chen, Jiquan; Davis, Kenneth J; Dellwik, Ebba; Desai, Ankur R; Etzold, Sophia; Francois, Louis; Gianelle, Damiano; Gielen, Bert; Goldstein, Allen; Groenendijk, Margriet; Gu, Lianhong; Hanan, Niall; Helfter, Carole; Hirano, Takashi; Hollinger, David Y; Jones, Mike B; Kiely, Gerard; Kolb, Thomas E; Kutsch, Werner L; Lafleur, Peter; Lawrence, David M; Li, Linghao; Lindroth, Anders; Litvak, Marcy; Loustau, Denis; Lund, Magnus; Marek, Michal; Martin, Timothy A; Matteucci, Giorgio; Migliavacca, Mirco; Montagnani, Leonardo; Moors, Eddy; Munger, J William; Noormets, Asko; Oechel, Walter; Olejnik, Janusz; Kyaw Tha Paw U; Pilegaard, Kim; Rambal, Serge; Raschi, Antonio; Scott, Russell L; Seufert, Günther; Spano, Donatella; Stoy, Paul; Sutton, Mark A; Varlagin, Andrej; Vesala, Timo; Weng, Ensheng; Wohlfahrt, Georg; Yang, Bai; Zhang, Zhongda; Zhou, Xuhui

    2012-05-01

    • It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not been examined at broad spatial and temporal scales. • Here, we compiled data from 169 globally distributed sites of eddy covariance and quantified the temperature response functions of net ecosystem exchange (NEE), an ecosystem-level property, to determine whether NEE shows thermal optimality and to explore the underlying mechanisms. • We found that the temperature response of NEE followed a peak curve, with the optimum temperature (corresponding to the maximum magnitude of NEE) being positively correlated with annual mean temperature over years and across sites. Shifts of the optimum temperature of NEE were mostly a result of temperature acclimation of gross primary productivity (upward shift of optimum temperature) rather than changes in the temperature sensitivity of ecosystem respiration. • Ecosystem-level thermal optimality is a newly revealed ecosystem property, presumably reflecting associated evolutionary adaptation of organisms within ecosystems, and has the potential to significantly regulate ecosystem-climate change feedbacks. The thermal optimality of NEE has implications for understanding fundamental properties of ecosystems in changing environments and benchmarking global models.

  12. Net air emissions from electric vehicles: the effect of carbon price and charging strategies.

    Science.gov (United States)

    Peterson, Scott B; Whitacre, J F; Apt, Jay

    2011-03-01

    Plug-in hybrid electric vehicles (PHEVs) may become part of the transportation fleet on time scales of a decade or two. We calculate the electric grid load increase and emissions due to vehicle battery charging in PJM and NYISO with the current generation mix, the current mix with a $50/tonne CO(2) price, and this case but with existing coal generators retrofitted with 80% CO(2) capture. We also examine all new generation being natural gas or wind+gas. PHEV fleet percentages between 0.4 and 50% are examined. Vehicles with small (4 kWh) and large (16 kWh) batteries are modeled with driving patterns from the National Household Transportation Survey. Three charging strategies and three scenarios for future electric generation are considered. When compared to 2020 CAFE standards, net CO(2) emissions in New York are reduced by switching from gasoline to electricity; coal-heavy PJM shows somewhat smaller benefits unless coal units are fitted with CCS or replaced with lower CO(2) generation. NO(X) is reduced in both RTOs, but there is upward pressure on SO(2) emissions or allowance prices under a cap.

  13. Land-cover effects on soil organic carbon stocks in a European city.

    Science.gov (United States)

    Edmondson, Jill L; Davies, Zoe G; McCormack, Sarah A; Gaston, Kevin J; Leake, Jonathan R

    2014-02-15

    Soil is the vital foundation of terrestrial ecosystems storing water, nutrients, and almost three-quarters of the organic carbon stocks of the Earth's biomes. Soil organic carbon (SOC) stocks vary with land-cover and land-use change, with significant losses occurring through disturbance and cultivation. Although urbanisation is a growing contributor to land-use change globally, the effects of urban land-cover types on SOC stocks have not been studied for densely built cities. Additionally, there is a need to resolve the direction and extent to which greenspace management such as tree planting impacts on SOC concentrations. Here, we analyse the effect of land-cover (herbaceous, shrub or tree cover), on SOC stocks in domestic gardens and non-domestic greenspaces across a typical mid-sized U.K. city (Leicester, 73 km(2), 56% greenspace), and map citywide distribution of this ecosystem service. SOC was measured in topsoil and compared to surrounding extra-urban agricultural land. Average SOC storage in the city's greenspace was 9.9 kg m(-2), to 21 cm depth. SOC concentrations under trees and shrubs in domestic gardens were greater than all other land-covers, with total median storage of 13.5 kg m(-2) to 21 cm depth, more than 3 kg m(-2) greater than any other land-cover class in domestic and non-domestic greenspace and 5 kg m(-2) greater than in arable land. Land-cover did not significantly affect SOC concentrations in non-domestic greenspace, but values beneath trees were higher than under both pasture and arable land, whereas concentrations under shrub and herbaceous land-covers were only higher than arable fields. We conclude that although differences in greenspace management affect SOC stocks, trees only marginally increase these stocks in non-domestic greenspaces, but may enhance them in domestic gardens, and greenspace topsoils hold substantial SOC stores that require protection from further expansion of artificial surfaces e.g. patios and driveways.

  14. Spatiotemporal Changes of Built-Up Land Expansion and Carbon Emissions Caused by the Chinese Construction Industry.

    Science.gov (United States)

    Chuai, Xiaowei; Huang, Xianjin; Lu, Qinli; Zhang, Mei; Zhao, Rongqin; Lu, Junyu

    2015-11-01

    China is undergoing rapid urbanization, enlarging the construction industry, greatly expanding built-up land, and generating substantial carbon emissions. We calculated both the direct and indirect carbon emissions from energy consumption (anthropogenic emissions) in the construction sector and analyzed built-up land expansion and carbon storage losses from the terrestrial ecosystem. According to our study, the total anthropogenic carbon emissions from the construction sector increased from 3,905×10(4) to 103,721.17×10(4) t from 1995 to 2010, representing 27.87%-34.31% of the total carbon emissions from energy consumption in China. Indirect carbon emissions from other industrial sectors induced by the construction sector represented approximately 97% of the total anthropogenic carbon emissions of the sector. These emissions were mainly concentrated in seven upstream industry sectors. Based on our assumptions, built-up land expansion caused 3704.84×10(4) t of carbon storage loss from vegetation between 1995 and 2010. Cropland was the main built-up land expansion type across all regions. The study shows great regional differences. Coastal regions showed dramatic built-up land expansion, greater carbon storage losses from vegetation, and greater anthropogenic carbon emissions. These regional differences were the most obvious in East China followed by Midsouth China. These regions are under pressure for strong carbon emissions reduction.

  15. Carbon implications of Virgin Lands Campaign cropland expansion and post-Soviet agricultural land abandonment in Russia and Kazakhstan

    Science.gov (United States)

    Prishchepov, A. V.; Kurganova, I.; Schierhorn, F.; Lopes de Gerenyu, V.; Müller, D.; Kuzyakov, Y.

    2015-12-01

    Political economy and institutional changes regarding land use play crucial role in shaping land cover worldwide. Among such events was the Soviet Virgin Lands Campaign, when 45.2 million ha of virgin steppes were ploughed up from 1954 to 1963 in northern Eurasia. We took opportunity to evaluate carbon (C) costs of this Campaign, particularly with the account of massive cropland abandonment in the former Campaign area after demise of the Soviet Union in 1991. Within cropland mask produced with remotely sensed data, we spatially disaggregated historical annual sown area statistics at the provincial level for Russia and Kazakhstan based on cropland suitability assessment. We also adjusted our cropland allocation model with the use of 1:3,000,000 map depicting cropland expansion in Northern Kazakhstan. We used C bookkeeping approach to assess C dynamics based on soil stratification and C field measurements. The Campaign resulted in huge C losses from soils, which accounted for 611±47 Mt C in Russia and 241±11 Mt C in Kazakhstan for upper 0-50 cm soil layer during the first 20 years of cultivation. Such C losses could be compared with C losses due to plowing up the prairies in the mid-1930s in USA. Despite the huge C losses from soils during the Campaign, the total C budget in soils of both countries at national level was positive after 1991 due to sequestered C on abandoned lands, albeit the patterns of C loss during the Campaign and C sink in post-Soviet period differed. The C sink from 1991 to 2010 on abandoned croplands in Russia (45.5Mha) comprised 976±108Mt C and Kazakhstan (12.9Mha) comprised 240±34Mt C. However, already ongoing recultivation of abandoned cropland in Kazakhstan and already planned such activities in Russia, can release stored C on abandoned lands. Our study highlights the importance of environmental evaluation of such governmental programs and their alternatives, particularly, since such programs are not rare events in modern land

  16. Typhoons exert significant but differential impact on net carbon ecosystem exchange of subtropical mangrove ecosystems in China

    Directory of Open Access Journals (Sweden)

    H. Chen

    2014-06-01

    Full Text Available Typhoons are very unpredictable natural disturbances to subtropical mangrove forests in Asian countries, but litter information is available on how these disturbances affect ecosystem level carbon dioxide (CO2 exchange of mangrove wetlands. In this study, we examined short-term effect of frequent strong typhoons on defoliation and net ecosystem CO2 exchange (NEE of subtropical mangroves, and also synthesized 19 typhoons during a 4-year period between 2009 and 2012 to further investigate the regulation mechanisms of typhoons on ecosystem carbon and water fluxes following typhoon disturbances. Strong wind and intensive rainfall caused defoliation and local cooling effect during typhoon season. Daily total NEE values were decreased by 26–50% following some typhoons (e.g. W28-Nockten, W35-Molave and W35-Lio-Fan, but were significantly increased (43–131% following typhoon W23-Babj and W38-Megi. The magnitudes and trends of daily NEE responses were highly variable following different typhoons, which were determined by the balance between the variances of gross ecosystem production (GEP and ecosystem respiration (RE. Furthermore, results from our synthesis indicated that the landfall time of typhoon, wind speed and rainfall were the most important factors controlling the CO2 fluxes following typhoon events. These findings not only indicate that mangrove ecosystems have strong resilience to the frequent typhoon disturbances, but also demonstrate the damage of increasing typhoon intensity and frequency on subtropical mangrove ecosystems under future global climate change scenarios.

  17. Net energy yield and carbon footprint of summer corn under different N fertilizer rates in the North China Plain

    Institute of Scientific and Technical Information of China (English)

    WANG Zhan-biao; WEN Xin-ya; ZHANG Hai-lin; LU Xiao-hong; CHEN Fu

    2015-01-01

    Excessive use of N fertilizer in intensive agriculture can increase crop yield and at the same time cause high carbon (C) emissions. This study was conducted to determine optimized N fertilizer application for high grain yield and lower C emissions in summer corn (Zea mays L.). A ifeld experiment, including 0 (N0), 75 (N75), 150 (N150), 225 (N225), and 300 (N300) kg N ha–1 treatments, was carried out during 2010–2012 in the North China Plain (NCP). The results showed that grain yield, input energy, greenhouse gas (GHG) emissions, and carbon footprint (CF) were al increased with the increase of N rate, except net energy yield (NEY). The treatment of N225 had the highest grain yield (10 364.7 kg ha–1) and NEY (6.8%), but the CF (0.25) was lower than that of N300, which indicates that a rate of 225 kg N ha–1 can be optimal for summer corn in NCP. Comparing GHG emision compontents, N fertilizer (0–51.1%) was the highest and fol owed by electricity for irrigation (19.73–49.35%). We conclude that optimazing N fertilizer application rate and reducing electricity for irrigation are the two key measures to increase crop yield, improve energy efifciency and decrease GHG emissions in corn production.

  18. Topographical optimisation of single-storey non-domestic steel framed buildings using photovoltaic panels for net-zero carbon impact

    OpenAIRE

    McKinstray, Ross; Lim, James B P; Tanyimboh, Tiku T.; Phan, Duoc T.; Sha, Wei; Brownlee, Alexander E. L.

    2015-01-01

    A methodology is presented that combines a multi-objective evolutionary algorithm and artificial neural networks to optimise single-storey steel commercial buildings for net-zero carbon impact. Both symmetric and asymmetric geometries are considered in conjunction with regulated, unregulated and embodied carbon. Offsetting is achieved through photovoltaic (PV) panels integrated into the roof. Asymmetric geometries can increase the south facing surface area and consequently allow for improved ...

  19. Simulating carbon, water and energy fluxes of a rainforest and an oil palm plantation using the Community Land Model (CLM4.5)

    Science.gov (United States)

    Fan, Yuanchao; Bernoux, Martial; Roupsard, Olivier; Panferov, Oleg; Le Maire, Guerric; Tölle, Merja; Knohl, Alexander

    2014-05-01

    Deforestation and forest degradation driven by the expansion of oil palm (Elaeis guineensis) plantations has become the major source of GHG emission in Indonesia. Changes of land surface properties (e.g. vegetation composition, soil property, surface albedo) associated with rainforest to oil palm conversion might alter the patterns of land-atmosphere energy, water and carbon cycles and therefore affect local or regional climate. Land surface modeling has been widely used to characterize the two-way interactions between climate and human disturbances on land surface. The Community Land Model (CLM) is a third-generation land model that simulates a wide range of biogeophysical and biogeochemical processes. This project utilizes the land-cover/land-use change (LCLUC) capability of the latest CLM versions 4/4.5 to characterize quantitatively how anthropogenic land surface dynamics in Indonesia affect land-atmosphere carbon, water and energy fluxes. Before simulating land use changes, the first objective is to parameterize and validate the CLM model at local rainforest and oil palm plantation sites through separate point simulations. This entails creation and parameterization of a new plant functional type (PFT) for oil palm, as well as sensitivity analysis and adaptation of model parameters for the rainforest PFTs. CLM modelled fluxes for the selected sites are to be compared with field observations from eddy covariance (EC) flux towers (e.g. a rainforest site in Bariri, Sulawesi; an oil palm site in Jambi, Sumatra). After validation, the project will proceed to parameterize land-use transformation system using remote sensing data and to simulate the impacts of historical LUCs on carbon, water and energy fluxes. Last but not least, the effects of future LUCs in Indonesia on the fluxes and carbon sequestration capacity will be investigated through scenario study. Historical land cover changes, especially oil palm coverage, are retrieved from Landsat or MODIS archival

  20. Grass invasion effects on forest soil carbon depend on landscape-level land use patterns.

    Science.gov (United States)

    Craig, Matthew E; Pearson, Scott M; Fraterrigo, Jennifer M

    2015-08-01

    Plant invasions can alter the quality and quantity of detrital and root-derived inputs entering a system, thereby influencing the activities of microbial decomposers and affecting the soil carbon cycle. The effect of these inputs on soil carbon storage is often conflicting, suggesting strong context dependency in the plant-decomposer relationship. Whether there is a generalizable pattern that explains this dependency remains relatively unexplored. Here, we (1) examine how invasion by the exotic grass Microstegium vimineum affects carbon cycling across a land use gradient, and (2) evaluate the importance of inorganic nitrogen availability and other environmental variables for explaining patterns in soil carbon. Using paired invaded and uninvaded plots, we quantified invasion effects on belowground carbon pools, extracellular enzyme activities, and native leaf litter decomposition in forests embedded in an urban, agricultural, or forested landscape matrix. Compared to the urban matrix, invasion-associated declines in total soil organic carbon in the forested and agricultural landscapes were 3.5 and 2.5 times greater, respectively. Inorganic nitrogen availability and M. vimineum biomass interacted to explain these patterns: when both nitrogen availability and M. vimineum biomass were high, invaded soils exhibited higher total organic carbon, unchanged particulate organic matter carbon, and higher mineral-associated organic matter carbon compared to adjacent uninvaded soils. Consistent with these patterns, activities of carbon-mineralizing enzymes were lower in invaded than in uninvaded soils when both nitrogen availability and M. vimineum biomass were high. By contrast,. decomposition of native leaf litter was faster when inorganic nitrogen availability and M. vimineum biomass were high. Our findings suggest that, although this invader may accelerate carbon cycling in forest soils, its effects on soil carbon storage largely depend on nitrogen availability and invader

  1. Climate and land use controls on soil organic carbon in the loess plateau region of China.

    Science.gov (United States)

    Dang, Yaai; Ren, Wei; Tao, Bo; Chen, Guangsheng; Lu, Chaoqun; Yang, Jia; Pan, Shufen; Wang, Guodong; Li, Shiqing; Tian, Hanqin

    2014-01-01

    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 of 1961-2005. Our results show that SOC storage increased by 0.27 Pg C on the Loess Plateau as a result of multiple environmental factors during the study period. About 55% (0.14 Pg C) of the SOC increase was caused by land conversion from cropland to grassland/forest owing to the government efforts to reduce soil erosion and improve the ecological conditions in the region. Historical climate change reduced SOC by 0.05 Pg C (approximately 19% of the total change) primarily due to a significant climate warming and a slight reduction in precipitation. Our results imply that the implementation of "Grain for Green" policy may effectively enhance regional soil carbon storage and hence starve off further soil erosion on the Loess Plateau.

  2. Ecosystem carbon stocks and sequestration potential of federal lands across the conterminous United States.

    Science.gov (United States)

    Tan, Zhengxi; Liu, Shuguang; Sohl, Terry L; Wu, Yiping; Young, Claudia J

    2015-10-13

    Federal lands across the conterminous United States (CONUS) account for 23.5% of the CONUS terrestrial area but have received no systematic studies on their ecosystem carbon (C) dynamics and contribution to the national C budgets. The methodology for US Congress-mandated national biological C sequestration potential assessment was used to evaluate ecosystem C dynamics in CONUS federal lands at present and in the future under three Intergovernmental Panel on Climate Change Special Report on Emission Scenarios (IPCC SRES) A1B, A2, and B1. The total ecosystem C stock was estimated as 11,613 Tg C in 2005 and projected to be 13,965 Tg C in 2050, an average increase of 19.4% from the baseline. The projected annual C sequestration rate (in kilograms of carbon per hectare per year) from 2006 to 2050 would be sinks of 620 and 228 for forests and grasslands, respectively, and C sources of 13 for shrublands. The federal lands' contribution to the national ecosystem C budget could decrease from 23.3% in 2005 to 20.8% in 2050. The C sequestration potential in the future depends not only on the footprint of individual ecosystems but also on each federal agency's land use and management. The results presented here update our current knowledge about the baseline ecosystem C stock and sequestration potential of federal lands, which would be useful for federal agencies to decide management practices to achieve the national greenhouse gas (GHG) mitigation goal.

  3. Implication of Land-Use and Land-Cover Change into Carbon Dioxide Emissions in Karang Gading and Langkat Timur Wildlife Reserve, North Sumatra, Indonesia

    OpenAIRE

    Mohammad Basyuni; Lollie Agustina Pancawaraswati Putri; Muammar Bakar Murni

    2015-01-01

    Mangrove forest in the context of climate change is important sector to be included in the inventory of greenhouse gas (GHG) emissions. The present study describes land-use and land-cover change during 2006–2012 of a mangrove forest conservation area, Karang Gading and Langkat Timur Laut Wildlife Reserve (KGLTLWR) in North Sumatra, Indonesia and their implications to carbon dioxide emissions. A land-use change matrix showed that the decrease of mangrove forest due to increases of other land-u...

  4. Estimating litter carbon stocks on forest land in the United States.

    Science.gov (United States)

    Domke, Grant M; Perry, Charles H; Walters, Brian F; Woodall, Christopher W; Russell, Matthew B; Smith, James E

    2016-07-01

    Forest ecosystems are the largest terrestrial carbon sink on earth, with more than half of their net primary production moving to the soil via the decomposition of litter biomass. Therefore, changes in the litter carbon (C) pool have important implications for global carbon budgets and carbon emissions reduction targets and negotiations. Litter accounts for an estimated 5% of all forest ecosystem carbon stocks worldwide. Given the cost and time required to measure litter attributes, many of the signatory nations to the United Nations Framework Convention on Climate Change report estimates of litter carbon stocks and stock changes using default values from the Intergovernmental Panel on Climate Change or country-specific models. In the United States, the country-specific model used to predict litter C stocks is sensitive to attributes on each plot in the national forest inventory, but these predictions are not associated with the litter samples collected over the last decade in the national forest inventory. Here we present, for the first time, estimates of litter carbon obtained using more than 5000 field measurements from the national forest inventory of the United States. The field-based estimates mark a 44% reduction (2081±77Tg) in litter carbon stocks nationally when compared to country-specific model predictions reported in previous United Framework Convention on Climate Change submissions. Our work suggests that Intergovernmental Panel on Climate Change defaults and country-specific models used to estimate litter carbon in temperate forest ecosystems may grossly overestimate the contribution of this pool in national carbon budgets.

  5. Influence of net ecosystem metabolism in transferring riverine organic carbon to atmospheric CO2 in a tropical coastal lagoon (Chilka Lake, India)

    Digital Repository Service at National Institute of Oceanography (India)

    Gupta, G.V.M.; Sarma, V.V.S.S.; Robin, R.S.; Raman, A.V.; JaiKumar, M.; Rakesh, M.; Subramanian, B.R.

    in monsoon was contributed by its supply from rivers and the rest was contributed by in situ heterotrophic activity. Based on oxygen and total carbon mass balance, net ecosystem production (NEP) of lake (- 308 mmolC m sup(-2) d sup(-1) approx. equal to - 3...

  6. Atmospheric deposition, CO2, and change in the land carbon sink

    DEFF Research Database (Denmark)

    Martinez-Fernandez, Cristina; Vicca, Sara; Janssens, Ivan A.

    2017-01-01

    Concentrations of atmospheric carbon dioxide (CO2) have continued to increase whereas atmospheric deposition of sulphur and nitrogen has declined in Europe and the USA during recent decades. Using time series of flux observations from 23 forests distributed throughout Europe and the USA......, and generalised mixed models, we found that forest-level net ecosystem production and gross primary production have increased by 1% annually from 1995 to 2011. Statistical models indicated that increasing atmospheric CO2 was the most important factor driving the increasing strength of carbon sinks...... in these forests. We also found that the reduction of sulphur deposition in Europe and the USA lead to higher recovery in ecosystem respiration than in gross primary production, thus limiting the increase of carbon sequestration. By contrast, trends in climate and nitrogen deposition did not significantly...

  7. Modeling the significance of including C redistribution when determining changes in net carbon storage along a cultivated toposequence

    Science.gov (United States)

    Chirinda, Ngonidzashe; Olesen, Jørgen E.; Heckrath, Goswin; Paradelo Pérez, Marcos; Taghizadeh-Toosi, Arezoo

    2016-04-01

    Globally, soil carbon (C) reserves are second only to those in the ocean, and accounts for a significant C reservoir. In the case of arable soils, the quantity of stored C is influenced by various factors (e.g. management practices). Currently, the topography related influences on in-field soil C dynamics remain largely unknown. However, topography is known to influence a multiplicity of factors that regulate C input, storage and redistribution. To understand the patterns and untangle the complexity of soil C dynamics in arable landscapes, our study was conducted with soils from shoulderslope and footslope positions on a 7.1 ha winter wheat field in western Denmark. We first collected soil samples from shoulderslope and footslope positions with various depth intervals down to 100 cm and analyzed them for physical and chemical properties including texture and soil organic C contents. In-situ carbon dioxide (CO2) concentrations were measured at different soil profile depths at both positions for a year. Soil moisture content and temperature at 5 and 40 cm depth was measured continuously. Additionally, surface soil CO2 fluxes at shoulderslope and footslope positions were measured. We then used measurement data collected from the two landscape positions to calibrate the one-dimensional mechanistic model SOILCO2 module of the HYDRUS-1D software package and obtained soil CO2 fluxes from soil profile at two landscape positions. Furthermore, we tested whether the inclusion of vertical and lateral soil C movement improved the modeling of C dynamics in cultivated landscapes. For that, soil profile CO2 fluxes were compared with those obtained using a simple process-based soil whole profile C model, C-TOOL, which was modified to include vertical and lateral movement of C on landscape. Our results highlight the need to consider vertical and lateral soil C movement in the modeling of C dynamics in cultivated landscapes, for better qualification of net carbon storage.

  8. Typhoons exert significant but differential impacts on net ecosystem carbon exchange of subtropical mangrove forests in China

    Science.gov (United States)

    Chen, H.; Lu, W.; Yan, G.; Yang, S.; Lin, G.

    2014-10-01

    Typhoons are very unpredictable natural disturbances to subtropical mangrove forests in Asian countries, but little information is available on how these disturbances affect ecosystem level carbon dioxide (CO2) exchange of mangrove wetlands. In this study, we examined short-term effect of frequent strong typhoons on defoliation and net ecosystem CO2 exchange (NEE) of subtropical mangroves, and also synthesized 19 typhoons during a 4-year period between 2009 and 2012 to further investigate the regulation mechanisms of typhoons on ecosystem carbon and water fluxes following typhoon disturbances. Strong wind and intensive rainfall caused defoliation and local cooling effect during the typhoon season. Daily total NEE values decreased by 26-50% following some typhoons (e.g., W28-Nockten, W35-Molave and W35-Lio-Fan), but significantly increased (43-131%) following typhoon W23-Babj and W38-Megi. The magnitudes and trends of daily NEE responses were highly variable following different typhoons, which were determined by the balance between the variances of gross ecosystem production (GEP) and ecosystem respiration (RE). Furthermore, results from our synthesis indicated that the landfall time of typhoon, wind speed and rainfall were the most important factors controlling the CO2 fluxes following typhoon events. These findings indicate that different types of typhoon disturbances can exert very different effects on CO2 fluxes of mangrove ecosystems and that typhoon will likely have larger impacts on carbon cycle processes in subtropical mangrove ecosystems as the intensity and frequency of typhoons are predicted to increase under future global climate change scenarios.

  9. Influence of land use changes on soil carbon stock and soil carbon erosion in a Mediterranean catchment

    Energy Technology Data Exchange (ETDEWEB)

    Boix-Fayos, C.; Martinez-Mena, M.; Vente, J. de; Albaladejo, J.

    2009-07-01

    The effect of changing land uses on the organic soil carbon (C) stock and the soil C transported by water erosion and buried in depositions wedges behring check-dams was estimated in a Mediterranean catchment in SE Spin. the 57% decrease in agricultural areas and 1.5-fold increase of the total forest cover between 1956 and 1997 induced an accumulation rate of total organic carbon (TOC) in the soil of 10.73 g m{sup -}2 yr{sup -}1. The mineral-associated organic carbon (MOC) represented the 70% of the soil carbon pool, the particulate organic carbon (POC) represented a 30% of the soil carbon pool. The average sediments/soil enrichment ratio at the sub catchment scale (8-125 ha) was 0.59{+-}0.43 g kg{sup -}1. Eroded soil C accounted for between 2% to 78% of the soil c stock in the first 5 cm of the soil in the subcatchments. the C erosion rate varied between 0.008 and 0.2 t ha{sup -}1 yr{sup -}1. (Author) 20 refs.

  10. [Effects of Different Land Uses on Soil Active Organic Carbon and Nitrogen Fractions in Jinyun Mountain].

    Science.gov (United States)

    Qi, Xin; Jiang, Chang-sheng; Hao, Qing-ju; Li, Jian-lin

    2015-10-01

    In this paper, we take Jinyun Mountain where located in Beibei district of Chongqing as the research object and explore the effect of different ways of land use on soil active organic carbon, nitrogen components by collecting the soil samples from 0 to 60 cm depth in subtropical evergreen broad-leaved forest (hereinafter referred to as the forest), abandoned land, orchard, farmland and measuring the content of MBC, MBN, DOC and DON. The research results show that the contents of soil MBC, MBN, DOC, DON are reduced with the increase of soil depth in four types of land using soils. Variance analysis of the single factor shows that four kinds of land uses have no significant difference in the contents of MBC, MBN and DON, but the DOC content of the abandoned land is significantly higher than that of other three kinds. It shows that the different ways of land use have no obvious effects on soil MBC, MBN and DON but the abandonment of slope cropland can significantly increase the content of soil DOC. There is no significant difference among the distribution ratio of MBN, DOC, DON in forest, abandoned land, orchard and farmland within the soil from 0 to 60 cm, but the distribution ratio of slope MBC is significantly higher than that of other three kinds. It means farmland soil organic carbon has a higher biological activity, this could due to the application of green manure, farmland manure and other organic fertilizers. Under different land utilizations, DOC/DON is the highest, MBC/MBN is the second, and SOC/TN is the lowest. It means the biological solidification of dissolved organic matter is the strongest, and the mineralization of soil organic matter is the most obvious. Under the four kinds of land uses, there are the lowest ratios in SOC/TN, MBC/MBN and DOC/DON in the farmland. And all the ratios are less than 20, which suggest that the mineralization of farmland soil organic matter is stronger and it's easy to cause the loss of soil carbon.

  11. Land Use Effects on Carbon Storage in Thailand Tropical Ecosystems

    Science.gov (United States)

    Kai, F.; Tostado, E.; Chidthaisong, A.; Tyler, S. C.

    2004-12-01

    Measurements of stable isotopes of C have proved to be of value in estimating soil organic C turnover times and in partitioning soil organic carbon (SOC) from different sources. Typically, the contrast between sources and estimates of C turnover have been studied in ecosystems where C-3 photosynthetic plants such as hardwoods have been replaced by C-4 photosynthetic plants from agriculture such as corn or sugarcane. Here we report concentrations and stable C isotope ratios of SOC from Thailand coastal mangrove forests and intrusive coastal aquaculture in the form of shrimp and wastewater treatment ponds. There are clear changes in both magnitude and 13C/12C of SOC at former mangrove sites which have been altered to make ponds for shrimp farming and wastewater treatment. For instance, total per cent C from 0-40 cm soil depth (average of four 10 cm layers at 2 sites) was 6.2±2.8% for mature mangrove, while it was only 0.5±0.4% for a 10-year old shrimp pond and 1.3±0.4% for an 8-year old water treatment pond. Previous studies of mangrove organic C balance have indicated that these inter-tidal forest ecosystems are a sink for C and that significant C is vested in both above- and below-ground biomass and stored in sediments. Mangrove forest disturbance by human activities clearly has the potential to affect C storage. Our data indicates that stable C isotope tracing will be of value in tracking changes in coastal forest-aquaecosystems just as it has been for forest-agroecosystems

  12. Carbon outcomes of major land-cover transitions in SE Asia

    DEFF Research Database (Denmark)

    Ziegler, Alan D.; Phelps, Jacob; Yuen, Jia Qi

    2012-01-01

    Policy makers across the tropics propose that carbon finance could provide incentives for forest frontier communities to transition away from swidden agriculture (slash-and-burn or shifting cultivation) to other systems that potentially reduce emissions and/or increase carbon sequestration. However...... changes that can be expected from many transitions, including the replacement of various types of swidden agriculture with oil palm, rubber, or some other types of agroforestry systems. These transitions are underway throughout Southeast Asia, and are at the heart of REDD+ debates. Exceptions...... that encourage land-cover conversion away from these [especially long-fallow] systems to other more cash-crop-oriented systems producing ambiguous carbon stock changes GÇô including oil palm and rubber. In some instances, lengthening fallow periods of an existing swidden system may produce substantial carbon...

  13. Incorporating land-use requirements and environmental constraints in low-carbon electricity planning for California.

    Science.gov (United States)

    Wu, Grace C; Torn, Margaret S; Williams, James H

    2015-02-17

    The land-use implications of deep decarbonization of the electricity sector (e.g., 80% below 1990 emissions) have not been well-characterized quantitatively or spatially. We assessed the operational-phase land-use requirements of different low-carbon scenarios for California in 2050 and found that most scenarios have comparable direct land footprints. While the per MWh footprint of renewable energy (RE) generation is initially higher, that of fossil and nuclear generation increases over time with continued fuel use. We built a spatially explicit model to understand the interactions between resource quality and environmental constraints in a high RE scenario (>70% of total generation). We found that there is sufficient land within California to meet the solar and geothermal targets, but areas with the highest quality wind and solar resources also tend to be those with high conservation value. Development of some land with lower conservation value results in lower average capacity factors, but also provides opportunity for colocation of different generation technologies, which could significantly improve land-use efficiency and reduce permitting, leasing, and transmission infrastructure costs. Basing siting decisions on environmentally-constrained long-term RE build-out requirements produces significantly different results, including better conservation outcomes, than implied by the current piecemeal approach to planning.

  14. Net Ecosystem Carbon Exchange and Evapotranspiration After the Felling of an Eucalyptus Forest

    Science.gov (United States)

    Pita, Gabriel; Rodrigues, Abel; Mateus, Antonio; Pereira, Santos J.

    2011-01-01

    Espirra site (38o38’N,8o36’W) is located in a 300ha Eucalyptus globulus plantation, with a Mediterranean type climate with a mean annual precipitation of 709mm and a mean annual air temperature of 15.9oC. The plantation was established in 1986 with about 1100 trees ha-1. A 33m observation tower was installed in 2002, with an eddy covariance system. A harvesting of trees was made at the end of the 2nd rotation period, from November to December 2006. During the last four years of the second rotation the coppice were 20m height. Harvesting was planned in order to initiate a new 12 year productive cycle. In October 2008 a first thinning was made in three fourths of emerging stems from stumps. At this stage the forest trees had a mean height of 6m. During the period of analyses the total annual precipitation has varied between a minimum of 248mmYr-1 (2005) to a maximum of 796mm Yr-1 (2007), pattern typical of a Mediterranean climate. The diminution of precipitation (and also how it is distributed along the year) affects the forest uptake of Carbon .The GPP and the TER show lower values in dry years, both in the adult forest as in the young one. The GPP of the growing eucalyptus has been affected by the dry year but also by the thinning that took place in Oct 2008. The Ecosystem total respiration shows high values after the felling ( the same order of magnitude as the forest before the felling) due to the leaves and branches that were left over the soil after the harvesting. Three years after the felling the GPP of the young forest is 61% the value of the adult forest (mean value, excluding the dry year). The seasonal pattern of TER is similar before and after the felling, but in the young forest the GPP is lower and the NEE becomes positive in winter time. In an annual base the growing eucalyptus forest only in the first year after felling was a source of carbon.

  15. Effects of silvopastoral system conversion into different land-use systems on soil carbon and nitrogen storage

    OpenAIRE

    Matos, E.S.; Freese, D.; Reinhard F. J. Hüttl

    2009-01-01

    In agricultural soils, the carbon stocks are affected by changes in land-use systems or management practices. When silvopastoral systems are converted to arable lands, an effective decrease in soil carbon stocks, mainly in upper soil layers is expected. The aim of this work was to evaluate total C and N stocks in soil after conversion of silvopastoral systems to different land-use systems. The study areas are located in northeast Germany and refer to different land-use systems comprising: 2 a...

  16. Relationships between net primary productivity and stand age for several forest types and their influence on China's carbon balance.

    Science.gov (United States)

    Wang, Shaoqiang; Zhou, Lei; Chen, Jingming; Ju, Weimin; Feng, Xianfeng; Wu, Weixing

    2011-06-01

    Affected by natural and anthropogenic disturbances such as forest fires, insect-induced mortality and harvesting, forest stand age plays an important role in determining the distribution of carbon pools and fluxes in a variety of forest ecosystems. An improved understanding of the relationship between net primary productivity (NPP) and stand age (i.e., age-related increase and decline in forest productivity) is essential for the simulation and prediction of the global carbon cycle at annual, decadal, centurial, or even longer temporal scales. In this paper, we developed functions describing the relationship between national mean NPP and stand age using stand age information derived from forest inventory data and NPP simulated by the BEPS (Boreal Ecosystem Productivity Simulator) model in 2001. Due to differences in ecobiophysical characteristics of different forest types, NPP-age equations were developed for five typical forest ecosystems in China (deciduous needleleaf forest (DNF), evergreen needleleaf forest in tropic and subtropical zones (ENF-S), deciduous broadleaf forest (DBF), evergreen broadleaf forest (EBF), and mixed broadleaf forest (MBF)). For DNF, ENF-S, EBF, and MBF, changes in NPP with age were well fitted with a common non-linear function, with R(2) values equal to 0.90, 0.75, 0.66, and 0.67, respectively. In contrast, a second order polynomial was best suitable for simulating the change of NPP for DBF, with an R(2) value of 0.79. The timing and magnitude of the maximum NPP varied with forest types. DNF, EBF, and MBF reached the peak NPP at the age of 54, 40, and 32 years, respectively, while the NPP of ENF-S maximizes at the age of 13 years. The highest NPP of DBF appeared at 122 years. NPP was generally lower in older stands with the exception of DBF, and this particular finding runs counter to the paradigm of age-related decline in forest growth. Evaluation based on measurements of NPP and stand age at the plot-level demonstrates the reliability

  17. Carbon storage of artificial forests in rehabilitated lands in the upper reaches of the Yellow River

    Institute of Scientific and Technical Information of China (English)

    HU Jianzhong

    2006-01-01

    We studied 10- to 27-year-old artificial forests on rehabilitated lands in the upper reaches of the Yellow River with the objective of comparing the carbon densities of various artificial and natural forests.Under artificial plantations,the vegetation layer (including roots) had a mean carbon density of 111.3 t/hm2,the litter layer a density of 5.1 t/hm2,and the soil layer a density of 64.9 t/hm2.These values accounted for 28.6%,13.8%,and 61.0% of their respective counterparts in the natural secondary forests under the same site conditions in the region.The ratios of carbon density among vegetation,litter,and soil pools were 39.6:1.8:58.6 for artificial forests and 57.4:2.7:39.9 for natural forests.The carbon densities of the vegetation and litter layers increased exponentially with forest age.The total carbon density ratios were also increasing gradually.Although the mean total carbon density of the artificial forests in the rehabilitated lands was 281.2 t/hm2 in the experimental area,it accounted for only 41.5% of the carbon density of the natural secondary forests (677.4 t/hm2).The annual increase in total carbon density of artificial forests was as high as 15.2 t/hm2,which was 11.7% more than that of natural forests and 6.8 times higher than that (1.95 t/hm) of artificial forests in the entire country as measured during 1994-1998.This indicates that growth and carbon storage capacity of artificial forests in the rehabilitated lands were higher than those of forests on the barren hills and the secondary forests.We concluded that the conversion project from croplands to forests and grasslands based on scientific principles is very important in the formation of carbon sinks for reducing greenhouse effects.

  18. A comparison of soil organic carbon stock in ancient and modern land use systems in Denmark

    DEFF Research Database (Denmark)

    Breuning-Madsen, Henrik; Elberling, Bo; Balstrøm, Thomas

    2009-01-01

    During the South Scandinavian Early Bronze Age about 3300 years ago, thousands of burial mounds were constructed of sods from fallow ground used for grazing in Denmark and northern Germany. In some of these mounds a wet, anaerobic core developed, preventing the decomposition of organic matter....... A comparison of the organic matter content in these mound cores and the plough layer in modern farmland offers an opportunity to compare the soil organic carbon (SOC) stocks in ancient and modern land use systems and to evaluate the long-term trends in carbon (C) sequestration in relation to modern farmland...

  19. Simultaneous reductions in emissions of black carbon and co-emitted species will weaken the aerosol net cooling effect

    Science.gov (United States)

    Wang, Z. L.; Zhang, H.; Zhang, X. Y.

    2015-04-01

    Black carbon (BC), a distinct type of carbonaceous material formed from the incomplete combustion of fossil and biomass based fuels under certain conditions, can interact with solar radiation and clouds through its strong light-absorption ability, thereby warming the Earth's climate system. Some studies have even suggested that global warming could be slowed down in the short term by eliminating BC emission due to its short lifetime. In this study, we estimate the influence of removing some sources of BC and other co-emitted species on the aerosol radiative effect by using an aerosol-climate atmosphere-only model BCC_AGCM2.0.1_CUACE/Aero with prescribed sea surface temperature and sea ice cover, in combination with the aerosol emissions from the Representative Concentration Pathways (RCPs) scenarios. We find that the global annual mean aerosol net cooling effect at the top of the atmosphere (TOA) will be enhanced by 0.12 W m-2 compared with recent past year 2000 levels if the emissions of only BC are reduced to the level projected for 2100 based on the RCP2.6 scenario. This will be beneficial~for the mitigation of global warming. However, both aerosol negative direct and indirect radiative effects are weakened when BC and its co-emitted species (sulfur dioxide and organic carbon) are simultaneously reduced. Relative to year 2000 levels, the global annual mean aerosol net cooling effect at the TOA will be weakened by 1.7-2.0 W m-2 if the emissions of all these aerosols are decreased to the levels projected for 2100 in different ways based on the RCP2.6, RCP4.5, and RCP8.5 scenarios. Because there are no effective ways to remove the BC exclusively without influencing the other co-emitted components, our results therefore indicate that a reduction in BC emission can lead to an unexpected warming on the Earth's climate system in the future.

  20. A comparison of soil organic carbon stock in ancient and modern land use systems in Denmark

    DEFF Research Database (Denmark)

    Breuning-Madsen, Henrik; Elberling, Bo; Balstrøm, Thomas;

    2009-01-01

    . A comparison of the organic matter content in these mound cores and the plough layer in modern farmland offers an opportunity to compare the soil organic carbon (SOC) stocks in ancient and modern land use systems and to evaluate the long-term trends in carbon (C) sequestration in relation to modern farmland......During the South Scandinavian Early Bronze Age about 3300 years ago, thousands of burial mounds were constructed of sods from fallow ground used for grazing in Denmark and northern Germany. In some of these mounds a wet, anaerobic core developed, preventing the decomposition of organic matter...... with varying inputs of manure and inorganic fertilizers. In the present paper we compare SOC stocks based on integrated horizon-specific densities and SOC contents in three 3300-year-old buried farmland soils, representing the land use system at that time, with results from soil surveys representing modern...

  1. Australian net (1950s–1990) soil organic carbon erosion: implications for CO2 emission and land–atmosphere modelling

    OpenAIRE

    A. Chappell; N. P. Webb; Viscarra Rossel, R.A.; Bui, E.

    2014-01-01

    The debate remains unresolved about soil erosion substantially offsetting fossil fuel emissions and acting as an important source or sink of CO2. There is little historical land use and management context to this debate, which is central to Australia's recent past of European settlement, agricultural expansion and agriculturally-induced soil erosion. We use "catchment" scale (∼25 km2) estimates of 137Cs-derived net (1950s–1990) soil redistribution of all processes (wind,...

  2. Australian net (1950s–1990) soil organic carbon erosion: implications for CO2 emission and land–atmosphere modelling

    OpenAIRE

    A. Chappell; N. P. Webb; Viscarra Rossel, R.A.; Bui, E.

    2014-01-01

    The debate about soil erosion substantially offsetting fossil fuel emissions and acting as an important source or sink of CO2 remains unresolved. There is little historical land use and management context to this debate which is central to Australia's recent past of European settlement, agricultural expansion and agriculturally-induced soil erosion. We use "catchment" scale (∼25 km2) estimates of 137Cs-derived net (1950s–1990) soil redistribution of all processes...

  3. Land Use Strategies for Optimizing Carbon Sequestration within the Head of the Lower Mississippi Watershed

    Science.gov (United States)

    Weaver, L.

    2015-12-01

    The world is currently in a stage of extreme growth, characterized by increasing demands for food and increasing greenhouse gas emissions. The population for 2050 is forecasted to grow by 2.3 billion people, resulting in close to a 40% increase in food demand (Alexandratos, Bruinsma 2012). This will severely increase pressure on the earth and on crop harvesting processes to incorporate carbon emissions reduction strategies. Optimal land use analysis and innovation can provide feasible solutions for these problems. A key environmental feature around which land use systems should be carefully planned and maintained is the Mississippi River, the largest watershed system in the United States. Along head of the Lower Mississippi Watershed lie several farming communities including Cairo, Illinois. The primary land use for the area inhabited by these communities consists of soybeans, corn, and pasture. These crops have varying carbon storage capacities, economic and social benefits, and environmental consequences. In order to maximize social, economic, and environmental benefits and sustainability, these crops were analyzed over time, spatial correlation, and crop size area. When considering risks of carbon emissions, economic decline, landscape erosion and harmful runoff, a localized switchgrass buffer remains a feasible solution. Its strengths as a native, reliable plant with high carbon sequestration and biomass harvest potential yield it to be more prevalently implemented at the head of the Lower Mississippi Watershed. However, there are multiple factors that must be considered before implementing broad agricultural policies and practices. Thorough analyses should be performed frequently to assess the effects of major land use change and can be used to identify the optimized applications for farmers and communities.

  4. Carbon Calculator for Land Use Change from Biofuels Production (CCLUB) Users’ Manual and Technical Documentation

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, Jennifer B. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Qin, Zhangcai [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Mueller, Steffen [Univ. of Illinois, Chicago, IL (United States). Energy Resources Center; Kwon, Ho-young [International Food Policy Research Institute (IFPRI), Washington, DC (United States); Wander, Michelle M. [Univ. of Illinois at Urbana Champaign, Urbana, IL (United States). Dept. of Natural Resources; Wang, Michael [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division

    2016-09-01

    The $\\underline{C}$arbon $\\underline{C}$alculator for $\\underline{L}$and $\\underline{U}$se Change from $\\underline{B}$iofuels Production (CCLUB) calculates carbon emissions from land use change (LUC) for four different ethanol production pathways including corn grain ethanol and cellulosic ethanol from corn stover, Miscanthus, and switchgrass. This document discusses the version of CCLUB released September 30, 2014 which includes corn and three cellulosic feedstocks: corn stover, Miscanthus, and switchgrass.

  5. BLAZE, a novel Fire-Model for the CABLE Land-Surface Model applied to a Re-Assessment of the Australian Continental Carbon Budget

    Science.gov (United States)

    Nieradzik, L. P.; Haverd, V. E.; Briggs, P.; Meyer, C. P.; Canadell, J.

    2015-12-01

    Fires play a major role in the carbon-cycle and the development of global vegetation, especially on the continent of Australia, where vegetation is prone to frequent fire occurences and where regional composition and stand-age distribution is regulated by fire. Furthermore, the probable changes of fire behaviour under a changing climate are still poorly understood and require further investigation.In this presentation we introduce the fire-model BLAZE (BLAZe induced land-atmosphere flux Estimator), designed for a novel approach to simulate fire-frequencies, fire-intensities, fire related fluxes and the responses in vegetation. Fire frequencies are prescribed using SIMFIRE (Knorr et al., 2014) or GFED3 (e.g. Giglio et al., 2013). Fire-Line-Intensity (FLI) is computed from meteorological information and fuel loads which are state variables within the C-cycle component of CABLE (Community Atmosphere-Biosphere-Land Exchange model). This FLI is used as an input to the tree-demography model POP(Population-Order-Physiology; Haverd et al., 2014). Within POP the fire-mortality depends on FLI and tree height distribution. Intensity-dependent combustion factors (CF) are then generated for and applied to live and litter carbon pools as well as the transfers from live pools to litter caused by fire. Thus, both fire and stand characteristics are taken into account which has a legacy effect on future events. Gross C-CO2 emissions from Australian wild fires are larger than Australian territorial fossil fuel emissions. However, the net effect of fire on the Australian terrestrial carbon budget is unknown. We address this by applying the newly-developed fire module, integrated within the CABLE land surface model, and optimised for the Australian region, to a reassessment of the Australian Terrestrial Carbon Budget.

  6. Partitioning net ecosystem carbon exchange into net assimilation and respiration using 13CO2 measurements: A cost-effective sampling strategy

    Science.gov (United States)

    OgéE, J.; Peylin, P.; Ciais, P.; Bariac, T.; Brunet, Y.; Berbigier, P.; Roche, C.; Richard, P.; Bardoux, G.; Bonnefond, J.-M.

    2003-06-01

    The current emphasis on global climate studies has led the scientific community to set up a number of sites for measuring the long-term biosphere-atmosphere net CO2 exchange (net ecosystem exchange, NEE). Partitioning this flux into its elementary components, net assimilation (FA), and respiration (FR), remains necessary in order to get a better understanding of biosphere functioning and design better surface exchange models. Noting that FR and FA have different isotopic signatures, we evaluate the potential of isotopic 13CO2 measurements in the air (combined with CO2 flux and concentration measurements) to partition NEE into FR and FA on a routine basis. The study is conducted at a temperate coniferous forest where intensive isotopic measurements in air, soil, and biomass were performed in summer 1997. The multilayer soil-vegetation-atmosphere transfer model MuSICA is adapted to compute 13CO2 flux and concentration profiles. Using MuSICA as a "perfect" simulator and taking advantage of the very dense spatiotemporal resolution of the isotopic data set (341 flasks over a 24-hour period) enable us to test each hypothesis and estimate the performance of the method. The partitioning works better in midafternoon when isotopic disequilibrium is strong. With only 15 flasks, i.e., two 13CO2 nighttime profiles (to estimate the isotopic signature of FR) and five daytime measurements (to perform the partitioning) we get mean daily estimates of FR and FA that agree with the model within 15-20%. However, knowledge of the mesophyll conductance seems crucial and may be a limitation to the method.

  7. Soil carbon sequestration or biofuel production: new land-use opportunities for mitigating climate over abandoned Soviet farmlands.

    Science.gov (United States)

    Vuichard, Nicolas; Ciais, Philippe; Wolf, Adam

    2009-11-15

    Although the CO(2) mitigation potential of biofuels has been studied by extrapolation of small-scale studies, few estimates exist of the net regional-scale carbon balance implications of biofuel cultivations programs, either growing conventional biofuel crops or applying new advanced technologies. Here we used a spatially distributed process-driven model over the 20 Mha of recently abandoned agricultural lands of the Former Soviet Union to quantify the GHG mitigation by biofuel production from Low Input/High Diversity (LIHD) grass-legume prairies and to compare this GHG mitigation with the one of soil C sequestration as it currently occurs. LIHD has recently received a lot of attention as an emerging opportunity to produce biofuels over marginal lands leading to a good energy efficiency with minimal adverse consequences on food security and ecosystem services. We found that, depending on the time horizon over which one seeks to maximize the GHG benefit, the optimal time for implementing biofuel production shifts from "never" (short-term horizon) to "as soon as possible" (longer-term horizon). These results highlight the importance of reaching agreement a priori on the target time interval during which biofuels are expected to play a role within the global energy system, to avoid deploying biofuel technology over a time interval for which it has a detrimental impact on the GHG mitigation objective. The window of opportunity for growing LIHD also stresses the need to reduce uncertainties in soil C inputs, turnover, and soil organic matter stability under current and future climate and management practices.

  8. Effects of long-term land use change on dissolved carbon characteristics in the permafrost streams of northeast China.

    Science.gov (United States)

    Guo, Yuedong; Song, Changchun; Wan, Zhongmei; Tan, Wenwen; Lu, Yongzheng; Qiao, Tianhua

    2014-11-01

    Permafrost soils act as large sinks of organic carbon but are highly sensitive to interference such as changes in land use, which can greatly influence dissolved carbon loads in streams. This study examines the effects of long-term land reclamation on seasonal concentrations of dissolved carbons in the upper reaches of the Nenjiang River, northeast China. A comparison of streams in natural and agricultural systems shows that the dissolved organic carbon (DOC) concentration is much lower in the agricultural stream (AG) than in the two natural streams (WAF, wetland dominated; FR, forest dominated), suggesting that land use change is associated with reduced DOC exporting capacity. Moreover, the fluorescence indexes and the ratio of dissolved carbon to nitrogen also differ greatly between the natural and agricultural streams, indicating that the chemical characteristics and the origin of the DOC released from the whole reaches are also altered to some extent. Importantly, the exporting concentration of dissolved inorganic carbon (DIC) and its proportion of total dissolved carbon (TDC) substantially increase following land reclamation, which would largely alter the carbon cycling processes in the downstream fluvial system. Although the strong association between the stream discharge and the DOC concentration was unchanged, the reduction in total soil organic carbon following land reclamation led to remarkable decline of the total flux and exporting coefficient of the dissolved carbons. The results suggest that dissolved carbons in permafrost streams have been greatly affected by changes in land use since the 1970s, and the changes in the concentration and chemical characteristics of dissolved carbons will last until the alteration in both the traditional agriculture pattern and the persistent reclamation activities.

  9. Net Operations

    Institute of Scientific and Technical Information of China (English)

    蒋昌俊; 吴哲辉

    1992-01-01

    Two kinds of net operations.addition and Cartesian production of P/T nets,are introduced.They are defined on the set of underlying net of P/T systems.The conditions for preserving structural properties of Petri net after these operations are discussed.It is shown that the set of P/T nets forms and Abelian group for net addition operation and the inverse net of a P/T net in usual meaning of net theory is exactly the inverse of this P/T net as an element of the P/T net group;and that the set of P/T nets forms an Abelian ring for net addition and Caresian product operations.

  10. Interacting effects of photoperiod and photosynthetic photon flux on net carbon assimilation and starch accumulation in potato leaves

    Science.gov (United States)

    Stutte, G. W.; Yorio, N. C.; Wheeler, R. M.

    1996-01-01

    The effect of photoperiod (PP) on net carbon assimilation rate (Anet) and starch accumulation in newly mature canopy leaves of 'Norland' potato (Solanum tuberosum L.) was determined under high (412 varies as mol m-2s-1) and low (263 varies as mol m-2s-1) photosynthetic photon flux (PPF) conditions. The Anet decreased from 13.9 to 11.6 and 9.3 micromoles m-2s-1, and leaf starch increased from 70 to 129 and 118 mg g-1 drymass (DM) as photoperiod (PP) was increased from 12/12 to 18/6, and 24/0, respectively. Longer PP had a greater effect with high PPF conditions than with low PPF treatments, with high PPF showing greater decline in Anet. Photoperiod did not affect either the CO2 compensation point (50 micromoles mol-1) or CO2 saturation point (1100-1200 micromoles mol-1) for Anet. These results show an apparent limit to the amount of starch that can be stored (approximately 15% DM) in potato leaves. An apparent feedback mechanism exists for regulating Anet under high PPF, high CO2, and long PP, but there was no correlation between Anet and starch concentration in individual leaves. This suggests that maximum Anet cannot be sustained with elevated CO2 conditions under long PP (> or = 12 hours) and high PPF conditions. If a physiological limit exists for the fixation and transport of carbon,then increasing photoperiod and light intensity under high CO2 conditions is not the most appropriate means to maximize the yield of potatoes.

  11. Effects of shifting seasonal rainfall patterns on net primary productivity and carbon storage in tropical seasonally dry ecosystems

    Science.gov (United States)

    Rohr, T.; Manzoni, S.; Feng, X.; Menezes, R.; Porporato, A. M.

    2013-12-01

    declining rainfall due to reduced soil respiration. a) Annual average net primary productivity and b) the temporally averaged ensemble soil carbon concentration are plotted against the length of the wet season T_W, for six annual rainfall rates (m yr-1).

  12. Estimating European soil organic carbon mitigation potential in a global integrated land use model

    Science.gov (United States)

    Frank, Stefan; Böttcher, Hannes; Schneider, Uwe; Schmid, Erwin; Havlík, Petr

    2013-04-01

    Several studies have shown the dynamic interaction between soil organic carbon (SOC) sequestration rates, soil management decisions and SOC levels. Management practices such as reduced and no-tillage, improved residue management and crop rotations as well as the conversion of marginal cropland to native vegetation or conversion of cultivated land to permanent grassland offer the potential to increase SOC content. Even though dynamic interactions are widely acknowledged in literature, they have not been implemented in most existing land use decision models. A major obstacle is the high data and computing requirements for an explicit representation of alternative land use sequences since a model has to be able to track all different management decision paths. To our knowledge no study accounted so far for SOC dynamics explicitly in a global integrated land use model. To overcome these conceptual difficulties described above we apply an approach capable of accounting for SOC dynamics in GLOBIOM (Global Biosphere Management Model), a global recursive dynamic partial equilibrium bottom-up model integrating the agricultural, bioenergy and forestry sectors. GLOBIOM represents all major land based sectors and therefore is able to account for direct and indirect effects of land use change as well as leakage effects (e.g. through trade) implicitly. Together with the detailed representation of technologies (e.g. tillage and fertilizer management systems), these characteristics make the model a highly valuable tool for assessing European SOC emissions and mitigation potential. Demand and international trade are represented in this version of the model at the level of 27 EU member states and 23 aggregated world regions outside Europe. Changes in the demand on the one side, and profitability of the different land based activities on the other side, are the major determinants of land use change in GLOBIOM. In this paper we estimate SOC emissions from cropland for the EU until

  13. Effects of Endogenous Factors on Regional Land-Use Carbon Emissions Based on the Grossman Decomposition Model: A Case Study of Zhejiang Province, China

    Science.gov (United States)

    Wu, Cifang; Li, Guan; Yue, Wenze; Lu, Rucheng; Lu, Zhangwei; You, Heyuan

    2015-02-01

    The impact of land-use change on greenhouse gas emissions has become a core issue in current studies on global change and carbon cycle. However, a comprehensive evaluation of the effects of land-use changes on carbon emissions is very necessary. This paper attempted to apply the Grossman decomposition model to estimate the scale, structural, and management effects of land-use carbon emissions based on final energy consumption by establishing the relationship between the types of land use and carbon emissions in energy consumption. It was shown that land-use carbon emissions increase from 169.5624 million tons in 2000 to 637.0984 million tons in 2010, with an annual average growth rate of 14.15 %. Meanwhile, land-use carbon intensity increased from 17.59 t/ha in 2000 to 64.42 t/ha in 2010, with an average annual growth rate of 13.86 %. The results indicated that rapid industrialization and urbanization in Zhejiang Province promptly increased urban land and industrial land, which consequently affected land-use extensive emissions. The structural and management effects did not mitigate land-use carbon emissions. By contrast, both factors evidently affected the growth of carbon emissions because of the rigid demands of energy-intensive land-use types and the absence of land management. Results called for the policy implications of optimizing land-use structures and strengthening land-use management.

  14. Net Primary Production and Carbon Stocks for Subarctic Mesic-Dry Tundras with Contrasting Microtopography, Altitude, and Dominant Species

    DEFF Research Database (Denmark)

    Campioli, Matteo; Michelsen, Anders; Demey, A;

    2009-01-01

    production was obtained from average species growth rates, previously assessed at the sites. Results showed that aboveground vascular NPP (15-270 g m-2), annual NPP (214-282 g m-2 or 102-137 g C m-2) and vegetation biomass (330-2450 g m-2) varied greatly among communities. Vegetation dominated by Empetrum......Mesic-dry tundras are widespread in the Arctic but detailed assessments of net primary production (NPP) and ecosystem carbon (C) stocks are lacking. We addressed this lack of knowledge by determining the seasonal dynamics of aboveground vascular NPP, annual NPP, and whole-ecosystem C stocks in five...... of the vegetation production occurred aboveground (85%). Ecosystem C and N stocks were 2100-8200 g C m-2 and 80-330 g N m-2, respectively, stored mainly in the soil turf and in the fine organic soil. Such stocks are comparable to the C and N stocks of moister tundra types, such as tussock tundra....

  15. [Evaluation of remote sensing extraction methods for vegetation phenology based on flux tower net ecosystem carbon exchange data].

    Science.gov (United States)

    Mou, Min-Jie; Zhu, Wen-Quan; Wang, Ling-Li; Xu, Ying-Jun; Liu, Jian-Hong

    2012-02-01

    Taking the vegetation phenological metrics derived from the net ecosystem carbon exchange (NEE) data of 72 flux towers in North America as the references, a comprehensive evaluation was conducted on the three typical classes of remote sensing extraction methods (threshold method, moving average method, and function fitting method) for vegetation phenology from the aspects of feasibility and accuracy. The results showed that the local midpoint threshold method had the highest feasibility and accuracy for extracting vegetation phenology, followed by the first derivative method based on fitted Logistic function. The feasibility and accuracy of moving average method were determined by the moving window size. As for the MODJS 16 d composited time-series normalized difference vegetation index (NDVI), the moving average method had preferable performance when the window size was set as 15. The global threshold method performed quite poor in the feasibility and accuracy. Though the values of the phenological metrics extracted by the curvature change rate method based on fitted Logistic function and the corresponding ones derived from NEE data had greater differences, there existed a strong correlation between them, indicating that the vegetation phenological metrics extracted by the curvature change rate method could reflect the real temporal and spatial variations of vegetation phenology.

  16. Carbon Storage Potential of Forest Land: A Comparative Study of Cases in Finland and Croatia

    Directory of Open Access Journals (Sweden)

    Martina Tijardović

    2013-06-01

    Full Text Available Background and Purpose: The concentrations of greenhouse gases in the atmosphere have been increasing over the last hundred years in relation to the Fourth IPCC assessment report that highlighted human activities as a direct influence on climate changes. Since Croatia and Finland signed the Kyoto Protocol, they are both committed to fulfil international obligations of lowering GHG’s emissions, enhancing the storage, as well as protecting and enhancing the current pools where the forestry sector has a prominent role. These obligations created a need for a review on carbon storage potentials for both countries with the aim of setting further scientific and management guidelines as the basic purpose of this research. Materials and Methods: Data collection was conducted within the scope of the Sort Term Scientific Mission (STSM in the period from May 2 – July 22, 2009 in the Finnish Forest Research Institute in Joensuu. The research encompassed an overview of literature, personal contacts with scientists and experts from both countries (research institutes, ministries, the EFI branch office in Joensuu and a field inspection which altogether provided an insight into the applied silvicultural and utilization activities. A significant data source were official documents and published project results on the carbon storage potential. Results and Discussion: Mitigation activities within the framework of the LULUCF project reduced the total emissions for 33.4 millions tons of CO2 equivalents in Finland in 2006 (this data has varied from 18 to 33.4 millions tons CO2 equivalents in the last fifteen years while for Croatia the availability of such data is limited. Finland has some former agricultural land which may be afforested but not in the substantial share, while in Croatia such areas amount to around 1 million ha. According to the climate change scenario for Finland (FINADAPT, predicting the largest climate changes, the total forest growth

  17. Effects of drought – altered seasonality and low rainfall – in net ecosystem carbon exchange of three contrasting Mediterranean ecosystems

    Directory of Open Access Journals (Sweden)

    A. Rodrigues

    2007-06-01

    Full Text Available Droughts cause reductions in gross primary production (GPP and also in net ecosystem exchange (NEE, contributing to most of the inter-annual variability in terrestrial carbon sequestration. In seasonally dry climates (Mediterranean droughts result from reductions in annual rainfall and from changes in rain seasonality. In western Iberia, the hydrological-year (i.e., from October to September of 2004–2005 was extremely dry, with precipitation 50% below the long-term mean (691 mm in 1961–1990, but 2005–2006 was normal. We compared the carbon fluxes measured by the eddy covariance technique from three contrasting ecosystems in southern Portugal: an evergreen oak woodland (savannah-like with ca. 21% tree cover; a Mediterranean C3/C4 grassland; and a coppiced eucalyptus plantation. During the dry hydrological-year of 2004–2005, NEE was lowest, the highest sink strength was in the eucalypt plantation (NEE = –399 g C m −2 year−1 as compared to the oak woodland (NEE = –88 g C m −2 year−1, and the grassland (NEE = +49 g C m −2 year −1. The latter was a source of carbon dioxide. The NEE values of the dry year were, however, much lower than those for wetter years, e.g. NEE = –861 g C m−2 year −1 in 2002–2003 in the eucalypt plantation. The NEE of the grassland and the oak savannah in the 2005–2006 hydrological-year, with annual precipitation above the long term mean, were –190 and –120 g C m −2 year−1, respectively. All ecosystems studied increased their rain-use efficiency (GPP per unit of rain volume increased in dry years. In the case of annual vegetation – grassland and low tree density woodland, however &ndash, rain-use efficiency decreased with severe drought. However, this was more pronounced in the eucalypt plantation due to greater GPP and the use of deep soil water resources. Although both calendar years of 2004 and 2005 had equally low rainfall, the effect of drought on the eucalypt plantation was

  18. Modelling the carbon and nitrogen balances of direct land use changes from energy crops in Denmark

    DEFF Research Database (Denmark)

    Hamelin, Lorie; Jørgensen, Uffe; Petersen, Bjørn Molt;

    2012-01-01

    This paper addresses the conversion of Danish agricultural land from food/feed crops to energy crops. To this end, a life cycle inventory, which relates the input and output flows from and to the environment of 528 different crop systems, is built and described. This includes seven crops (annuals......- and micronutrients are presented. The inventory results highlight Miscanthus as a promising energy crop, indicating it presents the lowest emissions of nitrogen compounds, the highest amount of carbon dioxide sequestrated from the atmosphere, a relatively high carbon turnover efficiency and allows to increase soil...... organic carbon. Results also show that the magnitude of these benefits depends on the harvest season, soil types and climatic conditions. Inventory results further highlight winter wheat as the only annual crop where straw removal for bioenergy may be sustainable, being the only annual crop not involving...

  19. Ozone pollution effects on the land carbon sink in the future greenhouse world

    Science.gov (United States)

    Unger, N.; Yue, X.

    2015-12-01

    Ozone pollution has huge impacts on the carbon balance in the United States, Europe and China. While terrestrial ecosystems provide an important sink for surface ozone through stomatal uptake, this process damages photosynthesis, reduces plant growth and biomass accumulation, and affects stomatal control over plant transpiration of water vapor. Effective mitigation of climate change by stabilizing atmospheric carbon dioxide concentrations requires improved understanding of ozone effects on the land carbon sink. Future effects of ozone pollution on the land carbon sink are largely unknown. We apply multiple observational datasets in combination with the Yale Interactive Terrestrial Biosphere (YIBs) model to quantify ozone vegetation damage in the present climatic state and for a broad range of possible futures. YIBs includes a mechanistic ozone damage model that affects both photosynthetic rate and stomatal conductance for low or high ozone plant sensitivity. YIBs is embedded in the NASA GISS ModelE2 global chemistry-climate model to allow a uniquely informed integration of plant physiology, atmospheric chemistry, and climate. The YIBs model has been extensively evaluated using land carbon flux measurements from 145 flux tower sites and multiple satellite products. Chronic ozone exposure in the present day reduces GPP by 11-23%, NPP by 8-16%, stomatal conductance by 8-17% and leaf area index by 2-5% in the summer time eastern United States. Similar response magnitudes are found in Europe but almost doubled damage effects occur in hotspots in eastern China. We investigate future ozone vegetation damage within the context of multiple global change drivers (physical climate change, carbon dioxide fertilization, human energy and agricultural emissions, human land use) at 2050 following the IPCC RCP2.6 and RCP8.5 scenarios. In the RCP8.5 world at 2050, growing season average GPP and NPP are reduced by 20-40% in China and 5-20% in the United States due to the global rise

  20. Land-use strategies to balance livestock production, biodiversity conservation and carbon storage in Yucatán, Mexico.

    Science.gov (United States)

    Williams, David R; Alvarado, Fredy; Green, Rhys E; Manica, Andrea; Phalan, Ben; Balmford, Andrew

    2017-06-14

    Balancing the production of food, particularly meat, with preserving biodiversity and maintaining ecosystem services is a major societal challenge. Research into the contrasting strategies of land sparing and land sharing has suggested that land sparing-combining high-yield agriculture with the protection or restoration of natural habitats on nonfarmed land-will have lower environmental impacts than other strategies. Ecosystems with long histories of habitat disturbance, however, could be resilient to low-yield agriculture and thus fare better under land sharing. Using a wider suite of species (birds, dung beetles and trees) and a wider range of livestock-production systems than previous studies, we investigated the probable impacts of different land-use strategies on biodiversity and aboveground carbon stocks in the Yucatán Peninsula, Mexico-a region with a long history of habitat disturbance. By modelling the production of multiple products from interdependent land uses, we found that land sparing would allow larger estimated populations of most species and larger carbon stocks to persist than would land sharing or any intermediate strategy. This result held across all agricultural production targets despite the history of disturbance and despite species richness in low- and medium-yielding agriculture being not much lower than that in natural habitats. This highlights the importance, in evaluating the biodiversity impacts of land use, of measuring population densities of individual species, rather than simple species richness. The benefits of land sparing for both biodiversity and carbon storage suggest that safeguarding natural habitats for biodiversity protection and carbon storage alongside promoting areas of high-yield cattle production would be desirable. However, delivering such landscapes will probably require the explicit linkage of livestock yield increases with habitat protection or restoration, as well as a deeper understanding of the long

  1. Linking carbon stock change from land-use change to consumption of agricultural products: Alternative perspectives.

    Science.gov (United States)

    Goh, Chun Sheng; Wicke, Birka; Faaij, André; Bird, David Neil; Schwaiger, Hannes; Junginger, Martin

    2016-11-01

    Agricultural expansion driven by growing demand has been a key driver for carbon stock change as a consequence of land-use change (CSC-LUC). However, its relative role compared to non-agricultural and non-productive drivers, as well as propagating effects were not clearly addressed. This study contributed to this subject by providing alternative perspectives in addressing these missing links. A method was developed to allocate historical CSC-LUC to agricultural expansions by land classes (products), trade, and end use. The analysis for 1995-2010 leads to three key trends: (i) agricultural land degradation and abandonment is found to be a major (albeit indirect) driver for CSC-LUC, (ii) CSC-LUC is spurred by the growth of cross-border trade, (iii) non-food use (excluding liquid biofuels) has emerged as a significant contributor of CSC-LUC in the 2000's. In addition, the study demonstrated that exact values of CSC-LUC at a single spatio-temporal point may change significantly with different methodological settings. For example, CSC-LUC allocated to 'permanent oil crops' changed from 0.53 Pg C (billion tonne C) of carbon stock gain to 0.11 Pg C of carbon stock loss when spatial boundaries were changed from global to regional. Instead of comparing exact values for accounting purpose, key messages for policymaking were drawn from the main trends. Firstly, climate change mitigation efforts pursued through a territorial perspective may ignore indirect effects elsewhere triggered through trade linkages. Policies targeting specific commodities or types of consumption are also unable to quantitatively address indirect CSC-LUC effects because the quantification changes with different arbitrary methodological settings. Instead, it is recommended that mobilising non-productive or under-utilised lands for productive use should be targeted as a key solution to avoid direct and indirect CSC-LUC.

  2. Water, land and carbon footprints of sheep and chicken meat produced in Tunisia under different farming systems

    NARCIS (Netherlands)

    Ibidhi, Ridha; Hoekstra, Arjen Y.; Gerbens-Leenes, P.Winnie; Chouchane, Hatem

    2017-01-01

    Meat production puts larger demands on water and land and results in larger greenhouse gas emissions than alternative forms of food. This study uses footprint indicators, the water, land and carbon footprint, to assess natural resources use and greenhouse gas emissions for sheep and chicken meat pro

  3. Carbon sequestration associated to the land-use and land-cover changes in the forestry sector in Southern Brazil

    Science.gov (United States)

    Ronquim, Carlos C.; Silva, Ramon F. B.; de Figueiredo, Eduardo B.; Bordonal, Ricardo O.; de C. Teixeira, Antônio H.; Cochasrk, Thomas C. D.; Leivas, Janice F.

    2016-10-01

    We studied the Paraíba do Sul river watershed, São Paulo state (PSWSP), Southeastern Brazil, in order to assess the land use and cover (LULC) and their implications to the amount of carbon (C) stored in the forest cover between the years 1985 and 2015. The region covers an area of 1,395,975 ha. We used images made by the Operational Land Imager (OLI) sensor (OLI/Landsat-8) to produce mappings, and image segmentation techniques to produce vectors with homogeneous characteristics. The training samples and the samples used for classification and validation were collected from the segmented image. To quantify the C stocked in aboveground live biomass (AGLB), we used an indirect method and applied literature-based reference values. The recovery of 205,690 ha of a secondary Native Forest (NF) after 1985 sequestered 9.7 Tg (Teragram) of C. Considering the whole NF area (455,232 ha), the amount of C accumulated along the whole watershed was 35.5 Tg, and the whole Eucalyptus crop (EU) area (113,600 ha) sequestered 4.4 Tg of C. Thus, the total amount of C sequestered in the whole watershed (NF + EU) was 39.9 Tg of C or 145.6 Tg of CO2, and the NF areas were responsible for the largest C stock at the watershed (89%). Therefore, the increase of the NF cover contributes positively to the reduction of CO2 concentration in the atmosphere, and Reducing Emissions from Deforestation and Forest Degradation (REDD+) may become one of the most promising compensation mechanisms for the farmers who increased forest cover at their farms.

  4. Land use change and carbon stock dynamics in Sub-Saharan Africa - Case study of Western Africa - Ghana

    Science.gov (United States)

    Grieco, E.; Chiti, T.; Valentini, R.

    2012-04-01

    Among different regions of the world, Africa and particularly sub-Saharan Africa (SSA) has contributed less than any other to the greenhouse gas emissions, but it is also the region most vulnerable and the least well equipped to the consequences. In SSA the role of land use change in controlling CO2 emissions may be more critical than in any other regions and perhaps the most uncertain component of the global carbon cycle. The most typical example of incomplete estimates will arise from the lack of reliable data for carbon pools. Three factors account for much of the rest of the uncertainty: (1) initial stocks of carbon in ecosystems affected by land-use change, (2) per hectare changes in carbon stocks in response to different types of land-use change, and (3) legacy effects; that is, the time it takes for carbon stocks to equilibrate following a change in land use. Considering the source of uncertainty and the lack of field data for SSA, the study has been located in Ghana (Jomoro district, Western Region) where forest is the only source of wood for domestic uses and deforestation annual rate was 2.2% for the period 2005-2010. This study analyze the above mentioned gaps by assessing: 1) initial carbon stocks (tropical rain forest), 2) per hectare changes in carbon stocks as consequence of deforestation followed by six different main land uses [tree plantations (rubber, coconut, cocoa, oil palm, mixed plantations) and a secondary forest], 3) dynamics of soil carbon stocks through the time considering chronosequences. When accounting changes in carbon stocks in the UNFCCC framework, it is required to consider 5 carbon pools that are: aboveground biomass, belowground biomass, litter, dead wood and soil. Within REDD+ mechanism it is clear that only aboveground pool has to be always considered, belowground biomass is recommended and the others are facultative. Evidence from official UNFCCC reports suggests that only a very small fraction of developing countries

  5. Influence of dynamic vegetation on carbon-nitrogen cycle feedback in the Community Land Model (CLM4)

    Science.gov (United States)

    Sakaguchi, K.; Zeng, X.; Leung, LR; Shao, P.

    2016-12-01

    Land carbon sensitivity to atmospheric CO2 concentration (βL) and climate warming (γL) is a crucial part of carbon-climate feedbacks that affect the magnitude of future warming. Although these sensitivities can be estimated by earth system models, their dependence on model representation of land carbon dynamics and the inherent model assumptions has rarely been investigated. Using the widely used Community Land Model version 4 as an example, we examine how βL and γL vary with prescribed versus dynamic vegetation covers. Both sensitivities are found to be larger with dynamic compared to prescribed vegetation on decadal timescale in the late twentieth century, with a more robust difference in γL. The latter is a result of dynamic vegetation model deficiencies in representing the competitions between deciduous versus evergreen trees and tree versus grass over the tropics and subtropics. The biased vegetation cover changes the regional characteristics of carbon-nitrogen cycles such that plant productivity responds less strongly to the enhancement of nitrogen mineralization with warming, so more carbon is lost to the atmosphere with rising temperature. The result calls for systematic evaluations of land carbon sensitivities with varying assumptions for land cover representations to help prioritize development effort and constrain uncertainties in carbon-climate feedbacks.

  6. Estimating carbon flux phenology with satellite-derived land surface phenology and climate drivers for different biomes: a synthesis of AmeriFlux observations.

    Directory of Open Access Journals (Sweden)

    Wenquan Zhu

    Full Text Available Carbon Flux Phenology (CFP can affect the interannual variation in Net Ecosystem Exchange (NEE of carbon between terrestrial ecosystems and the atmosphere. In this study, we proposed a methodology to estimate CFP metrics with satellite-derived Land Surface Phenology (LSP metrics and climate drivers for 4 biomes (i.e., deciduous broadleaf forest, evergreen needleleaf forest, grasslands and croplands, using 159 site-years of NEE and climate data from 32 AmeriFlux sites and MODIS vegetation index time-series data. LSP metrics combined with optimal climate drivers can explain the variability in Start of Carbon Uptake (SCU by more than 70% and End of Carbon Uptake (ECU by more than 60%. The Root Mean Square Error (RMSE of the estimations was within 8.5 days for both SCU and ECU. The estimation performance for this methodology was primarily dependent on the optimal combination of the LSP retrieval methods, the explanatory climate drivers, the biome types, and the specific CFP metric. This methodology has a potential for allowing extrapolation of CFP metrics for biomes with a distinct and detectable seasonal cycle over large areas, based on synoptic multi-temporal optical satellite data and climate data.

  7. Estimating carbon flux phenology with satellite-derived land surface phenology and climate drivers for different biomes: a synthesis of AmeriFlux observations.

    Science.gov (United States)

    Zhu, Wenquan; Chen, Guangsheng; Jiang, Nan; Liu, Jianhong; Mou, Minjie

    2013-01-01

    Carbon Flux Phenology (CFP) can affect the interannual variation in Net Ecosystem Exchange (NEE) of carbon between terrestrial ecosystems and the atmosphere. In this study, we proposed a methodology to estimate CFP metrics with satellite-derived Land Surface Phenology (LSP) metrics and climate drivers for 4 biomes (i.e., deciduous broadleaf forest, evergreen needleleaf forest, grasslands and croplands), using 159 site-years of NEE and climate data from 32 AmeriFlux sites and MODIS vegetation index time-series data. LSP metrics combined with optimal climate drivers can explain the variability in Start of Carbon Uptake (SCU) by more than 70% and End of Carbon Uptake (ECU) by more than 60%. The Root Mean Square Error (RMSE) of the estimations was within 8.5 days for both SCU and ECU. The estimation performance for this methodology was primarily dependent on the optimal combination of the LSP retrieval methods, the explanatory climate drivers, the biome types, and the specific CFP metric. This methodology has a potential for allowing extrapolation of CFP metrics for biomes with a distinct and detectable seasonal cycle over large areas, based on synoptic multi-temporal optical satellite data and climate data.

  8. Quantifying Net Carbon Exchanges Between the Atmosphere and Terrestrial Biosphere in the Arctic: What Have We Learned through Decade Regional Modeling Studies?

    Science.gov (United States)

    Zhuang, Q.

    2014-12-01

    Observed Arctic warming has been projected to continue in this century. Permafrost degradation is thus expected to continue, exposing large amounts of carbon for decomposition. Dynamics of Arctic landscape and hydrology are complicated due to changing climate and thawing permafrost, affecting the carbon biogeochemical cycling in the region. Further, human activities together with changing climate transform the regional land use and land cover, including wildfires, logging, and agricultural land conversion. This presentation will review the effects of factors, controls, and processes as well as landscape types (e.g., forests vs. lakes) on carbon biogeochemistry based on regional modeling studies and observations. Specific effects on carbon dynamics to be discussed will include: 1) thawing permafrost; 2) fire disturbances; 2) atmospheric carbon dioxide; 3) inorganic and organic nitrogen uptake by plants; 4) priming; 5) aerobic and anaerobic organic matter decomposition; and 6) various complexities of microbial physiology of soils. Partitioning the contribution of these processes to regional carbon dynamics shall help us improve the terrestrial biogeochemistry models, an important component of Earth System Models that are used to project our future climate.

  9. Fire-related carbon emissions from land use transitions in southern Amazonia

    Science.gov (United States)

    DeFries, R. S.; Morton, D. C.; van der Werf, G. R.; Giglio, L.; Collatz, G. J.; Randerson, J. T.; Houghton, R. A.; Kasibhatla, P. K.; Shimabukuro, Y.

    2008-11-01

    Various land-use transitions in the tropics contribute to atmospheric carbon emissions, including forest conversion for small-scale farming, cattle ranching, and production of commodities such as soya and palm oil. These transitions involve fire as an effective and inexpensive means for clearing. We applied the DECAF (DEforestation CArbon Fluxes) model to Mato Grosso, Brazil to estimate fire emissions from various land-use transitions during 2001-2005. Fires associated with deforestation contributed 67 Tg C/yr (17 and 50 Tg C/yr from conversion to cropland and pasture, respectively), while conversion of savannas and existing cattle pasture to cropland contributed 17 Tg C/yr and pasture maintenance fires 6 Tg C/yr. Large clearings (>100 ha/yr) contributed 67% of emissions but comprised only 10% of deforestation events. From a policy perspective, results imply that intensification of agricultural production on already-cleared land and policies to discourage large clearings would reduce the major sources of emissions from fires in this region.

  10. The LandCarbon Web Application: Advanced Geospatial Data Delivery and Visualization Tools for Communication about Ecosystem Carbon Sequestration and Greenhouse Gas Fluxes

    Science.gov (United States)

    Thomas, N.; Galey, B.; Zhu, Z.; Sleeter, B. M.; Lehmer, E.

    2015-12-01

    The LandCarbon web application (http://landcarbon.org) is a collaboration between the U.S. Geological Survey and U.C. Berkeley's Geospatial Innovation Facility (GIF). The LandCarbon project is a national assessment focused on improved understanding of carbon sequestration and greenhouse gas fluxes in and out of ecosystems related to land use, using scientific capabilities from USGS and other organizations. The national assessment is conducted at a regional scale, covers all 50 states, and incorporates data from remote sensing, land change studies, aquatic and wetland data, hydrological and biogeochemical modeling, and wildfire mapping to estimate baseline and future potential carbon storage and greenhouse gas fluxes. The LandCarbon web application is a geospatial portal that allows for a sophisticated data delivery system as well as a suite of engaging tools that showcase the LandCarbon data using interactive web based maps and charts. The web application was designed to be flexible and accessible to meet the needs of a variety of users. Casual users can explore the input data and results of the assessment for a particular area of interest in an intuitive and interactive map, without the need for specialized software. Users can view and interact with maps, charts, and statistics that summarize the baseline and future potential carbon storage and fluxes for U.S. Level 2 Ecoregions for 3 IPCC emissions scenarios. The application allows users to access the primary data sources and assessment results for viewing and download, and also to learn more about the assessment's objectives, methods, and uncertainties through published reports and documentation. The LandCarbon web application is built on free and open source libraries including Django and D3. The GIF has developed the Django-Spillway package, which facilitates interactive visualization and serialization of complex geospatial raster data. The underlying LandCarbon data is available through an open application

  11. Effect of climate change, CO2 trends, nitrogen addition, and land-cover and management intensity changes on the carbon balance of European grasslands.

    Science.gov (United States)

    Chang, Jinfeng; Ciais, Philippe; Viovy, Nicolas; Vuichard, Nicolas; Herrero, Mario; Havlík, Petr; Wang, Xuhui; Sultan, Benjamin; Soussana, Jean-François

    2016-01-01

    Several lines of evidence point to European managed grassland ecosystems being a sink of carbon. In this study, we apply ORCHIDEE-GM a process-based carbon cycle model that describes specific management practices of pastures and the dynamics of carbon cycling in response to changes in climatic and biogeochemical drivers. The model is used to simulate changes in the carbon balance [i.e., net biome production (NBP)] of European grasslands over 1991-2010 on a 25 km × 25 km grid. The modeled average trend in NBP is 1.8-2.0 g C m(-2)  yr(-2) during the past two decades. Attribution of this trend suggests management intensity as the dominant driver explaining NBP trends in the model (36-43% of the trend due to all drivers). A major change in grassland management intensity has occurred across Europe resulting from reduced livestock numbers. This change has 'inadvertently' enhanced soil C sequestration and reduced N2 O and CH4 emissions by 1.2-1.5 Gt CO2 -equivalent, offsetting more than 7% of greenhouse gas emissions in the whole European agricultural sector during the period 1991-2010. Land-cover change, climate change and rising CO2 also make positive and moderate contributions to the NBP trend (between 24% and 31% of the trend due to all drivers). Changes in nitrogen addition (including fertilization and atmospheric deposition) are found to have only marginal net effect on NBP trends. However, this may not reflect reality because our model has only a very simple parameterization of nitrogen effects on photosynthesis. The sum of NBP trends from each driver is larger than the trend obtained when all drivers are varied together, leaving a residual - nonattributed - term (22-26% of the trend due to all drivers) indicating negative interactions between drivers.

  12. Factors controlling carbon isotopic composition of land snail shells estimated from lab culturing experiment

    Science.gov (United States)

    Zhang, Naizhong; Yamada, Keita; Yoshida, Naohiro

    2014-05-01

    Carbon isotopic composition (δ13C) of land snail shell carbonate is widely applied in reconstructing the C3/C4 vegetation distribution of paleo-environment, which is considered to reflect variations of some environmental parameters [1][2][3]. Land snail shell carbon has three potential sources: diet, atmospheric CO2 and ingested carbonate (limestone) [4]. However, their relative contributions to shell carbonate have not been understood well yet [4][5][6][7][8]. More researches are necessary before we could apply this tool in paleo-environment reconstruction, especially inter-lab culturing experiment. A kind of land snail species, Acusta despecta sieboldiana, was collected at Yokohama, Japan and cultured under suitable environment to lay eggs. The second generations were growing up from eggs to adults around 6-12 months at the temperature of 20°, 25° and 30°, respectively. All of the snails at 25° and 30° and most of those at 20° were fed by cabbage (C3 plant) during their life span while others were fed by corn (C4 plant). To investigate the effect of ingested carbonate, some of them were fed by Ca3(PO4)2 powder while others were fed by CaCO3 powder. δ13C of shells were analyzed by an Isotope Ratio Mass Spectrometry (Thermo Finnigan MAT 253); δ13C of food and snail tissue were measured by a Cavity Ring-Down Spectroscopy (Picarro G1121-i). At the same time, δ13C of eggshell and new born snails were analyzed by a Continuous Flow Isotope Ratio Mass Spectrometry (GasBench II). We confirmed that diet, atmospheric CO2 and ingested limestone could be important sources controlling shell δ13C values. And the temperature could affect shell carbonate δ13C values, too. A simple but credible frame was raised to discuss the mechanism of how each possible source and environmental parameter could affect shell carbonate δ13C values based on previous works [4][6][8] and this study. According to this frame and some reasonable assumptions, we have estimated the

  13. Land use patterns and related carbon losses following deforestation in South America

    Science.gov (United States)

    De Sy, V.; Herold, M.; Achard, F.; Beuchle, R.; Clevers, J. G. P. W.; Lindquist, E.; Verchot, L.

    2015-12-01

    Land use change in South America, mainly deforestation, is a large source of anthropogenic CO2 emissions. Identifying and addressing the causes or drivers of anthropogenic forest change is considered crucial for global climate change mitigation. Few countries however, monitor deforestation drivers in a systematic manner. National-level quantitative spatially explicit information on drivers is often lacking. This study quantifies proximate drivers of deforestation and related carbon losses in South America based on remote sensing time series in a systematic, spatially explicit manner. Deforestation areas were derived from the 2010 global remote sensing survey of the Food and Agricultural Organisation Forest Resource Assessment. To assess proximate drivers, land use following deforestation was assigned by visual interpretation of high-resolution satellite imagery. To estimate gross carbon losses from deforestation, default Tier 1 biomass levels per country and eco-zone were used. Pasture was the dominant driver of forest area (71.2%) and related carbon loss (71.6%) in South America, followed by commercial cropland (14% and 12.1% respectively). Hotspots of deforestation due to pasture occurred in Northern Argentina, Western Paraguay, and along the arc of deforestation in Brazil where they gradually moved into higher biomass forests causing additional carbon losses. Deforestation driven by commercial cropland increased in time, with hotspots occurring in Brazil (Mato Grosso State), Northern Argentina, Eastern Paraguay and Central Bolivia. Infrastructure, such as urban expansion and roads, contributed little as proximate drivers of forest area loss (1.7%). Our findings contribute to the understanding of drivers of deforestation and related carbon losses in South America, and are comparable at the national, regional and continental level. In addition, they support the development of national REDD+ interventions and forest monitoring systems, and provide valuable input

  14. Baseline-Dependent Responses of Soil Organic Carbon Dynamics to Climate and Land Disturbances

    Directory of Open Access Journals (Sweden)

    Zhengxi Tan

    2013-01-01

    Full Text Available Terrestrial carbon (C sequestration through optimizing land use and management is widely considered a realistic option to mitigate the global greenhouse effect. But how the responses of individual ecosystems to changes in land use and management are related to baseline soil organic C (SOC levels still needs to be evaluated at various scales. In this study, we modeled SOC dynamics within both natural and managed ecosystems in North Dakota of the United States and found that the average SOC stock in the top 20 cm depth of soil lost at a rate of 450 kg C ha−1 yr−1 in cropland and 110 kg C ha−1 yr−1 in grassland between 1971 and 1998. Since 1998, the study area had become a SOC sink at a rate of 44 kg C ha−1 yr−1. The annual rate of SOC change in all types of lands substantially depends on the magnitude of initial SOC contents, but such dependency varies more with climatic variables within natural ecosystems and with management practices within managed ecosystems. Additionally, soils with high baseline SOC stocks tend to be C sources following any land surface disturbances, whereas soils having low baseline C contents likely become C sinks following conservation management.

  15. Atmospheric evidence for a global secular increase in carbon isotopic discrimination of land photosynthesis

    Science.gov (United States)

    Keeling, Ralph F.; Graven, Heather D.; Welp, Lisa R.; Resplandy, Laure; Bi, Jian; Piper, Stephen C.; Sun, Ying; Bollenbacher, Alane; Meijer, Harro A. J.

    2017-09-01

    A decrease in the 13C/12C ratio of atmospheric CO2 has been documented by direct observations since 1978 and from ice core measurements since the industrial revolution. This decrease, known as the 13C-Suess effect, is driven primarily by the input of fossil fuel-derived CO2 but is also sensitive to land and ocean carbon cycling and uptake. Using updated records, we show that no plausible combination of sources and sinks of CO2 from fossil fuel, land, and oceans can explain the observed 13C-Suess effect unless an increase has occurred in the 13C/12C isotopic discrimination of land photosynthesis. A trend toward greater discrimination under higher CO2 levels is broadly consistent with tree ring studies over the past century, with field and chamber experiments, and with geological records of C3 plants at times of altered atmospheric CO2, but increasing discrimination has not previously been included in studies of long-term atmospheric 13C/12C measurements. We further show that the inferred discrimination increase of 0.014 ± 0.007‰ ppm‑1 is largely explained by photorespiratory and mesophyll effects. This result implies that, at the global scale, land plants have regulated their stomatal conductance so as to allow the CO2 partial pressure within stomatal cavities and their intrinsic water use efficiency to increase in nearly constant proportion to the rise in atmospheric CO2 concentration.

  16. Effect of land use change on the carbon cycle in Amazon soils

    Science.gov (United States)

    Trumbore, Susan E.; Davidson, Eric A.

    1994-01-01

    The overall goal of this study was to provide a quantitative understanding of the cycling of carbon in the soils associated with deep-rooting Amazon forests. In particular, we wished to apply the understanding gained by answering two questions: (1) what changes will accompany the major land use change in this region, the conversion of forest to pasture? and (2) what is the role of carbon stored deeper than one meter in depth in these soils? To construct carbon budgets for pasture and forest soils we combined the following: measurements of carbon stocks in above-ground vegetation, root biomass, detritus, and soil organic matter; rates of carbon inputs to soil and detrital layers using litterfall collection and sequential coring to estimate fine root turnover; C-14 analyses of fractionated SOM and soil CO2 to estimate residence times; C-13 analyses to estimate C inputs to pasture soils from C-4 grasses; soil pCO2, volumetric water content, and radon gradients to estimate CO2 production as a function of soil depth; soil respiration to estimate total C outputs; and a model of soil C dynamics that defines SOM fractions cycling on annual, decadal, and millennial time scales.

  17. Effects of Land Management Practices on Labile Organic Carbon Fractions in Rice Cultivation

    Institute of Scientific and Technical Information of China (English)

    SHAO Jing'an; LI Yangbing; WEI Chaofu; XIE Deti

    2009-01-01

    A research trial with four land management practices, I.e., traditional tillage-fallow (TTF), traditional till-age-wheat (TTW), conservation tillage-fallow (CTF) and conservation tillage-wheat (CTW), was sampled in the 15th year after its establishment to assess the effects of different management practices on labile organic carbon fractions (LOCFs), such as easily oxidizable organic carbon (EOC), dissolved organic carbon (DOC), particulate organic carbon (POC) and microbial biomass carbon (MBC) in a typical paddy soil, Chongqing, Southwest China. The results indi-cated that LOCFs were significantly influenced by the combination of no-tillage, ridge culture and crop rotation. And,different combination patterns showed different effectiveness on soil LOCFs. The effects of no-tillage, ridge culture and wheat cultivation on EOC, DOC, POC and MBC mainly happened at 0-10cm. At this depth, soil under CTW had higher EOC, DOC, POC and MBC contents, compared to TTF, TTW and CTF, respectively. Moreover, the contents of LOCFs for different practices generally decreased when the soil depth increased. Our findings suggest that the paddy soil in Southwest China could be managed to concentrate greater quantities of EOC, DOC, POC and MBC.

  18. Scalable Dry Production Process of a Superior 3D Net-Like Carbon-Based Iron Oxide Anode Material for Lithium-Ion Batteries.

    Science.gov (United States)

    Li, Min; Du, Haoran; Kuai, Long; Huang, Kuangfu; Xia, Yuanyuan; Geng, Baoyou

    2017-10-02

    Carbon-based transition-metal oxides are considered as an appropriate anode material candidate for lithium-ion batteries. Herein, a simple and scalable dry production process is developed to produce carbon-encapsulated 3D net-like FeOx /C materials. The process is simply associated with the pyrolysis of a solid carbon source, such as filter paper, adsorbed with ferrite nitrate. The carbon derived from filter paper induces a carbothermal reduction to form metallic Fe, the addition of carbon and iron increase the conductivity of this material. As expected, this 3D net-like FeOx /C composite delivers an excellent charge capacity of 851.3 mAh g(-1) after 50 cycles at 0.2 A g(-1) as well as high stability and rate performance of 714.7 mAh g(-1) after 300 cycles at 1 A g(-1) . Superior performance, harmlessness, low costs, and high yield may greatly stimulate the practical application of the products as anode materials in lithium-ion batteries. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Land

    CSIR Research Space (South Africa)

    Audouin, M

    2007-01-01

    Full Text Available Unsustainable agricultural practices have had a role to play in the degradation of land on which agriculture depends. South Africa has an international obligation to develop a National Action Programme (NAP), the purpose of which is to identify...

  20. Estimation of Mangrove Net Primary Production and Carbon Sequestration service using Light Use Efficiency model in the Sunderban Biosphere region, India

    Science.gov (United States)

    Sannigrahi, Srikanta; Sen, Somnath; Paul, Saikat

    2016-04-01

    Net Primary Production (NPP) of mangrove ecosystem and its capacity to sequester carbon from the atmosphere may be used to quantify the regulatory ecosystem services. Three major group of parameters has been set up as BioClimatic Parameters (BCP): (Photosynthetically Active Radiation (PAR), Absorbed PAR (APAR), Fraction of PAR (FPAR), Photochemical Reflectance Index (PRI), Light Use Efficiency (LUE)), BioPhysical Parameters (BPP) :(Normalize Difference Vegetation Index (NDVI), scaled NDVI, Enhanced Vegetation Index (EVI), scaled EVI, Optimised and Modified Soil Adjusted Vegetation Index (OSAVI, MSAVI), Leaf Area Index (LAI)), and Environmental Limiting Parameters (ELP) (Temperature Stress (TS), Land Surface Water Index (LSWI), Normalize Soil Water Index (NSWI), Water Stress Scalar (WS), Inversed WS (iWS) Land Surface Temperature (LST), scaled LST, Vapor Pressure Deficit (VPD), scaled VPD, and Soil Water Deficit Index (SWDI)). Several LUE models namely Carnegie Ames Stanford Approach (CASA), Eddy Covariance - LUE (EC-LUE), Global Production Efficiency Model (GloPEM), Vegetation Photosynthesis Model (VPM), MOD NPP model, Temperature and Greenness Model (TG), Greenness and Radiation model (GR) and MOD17 was adopted in this study to assess the spatiotemporal nature of carbon fluxes. Above and Below Ground Biomass (AGB & BGB) was calculated using field based estimation of OSAVI and NDVI. Microclimatic zonation has been set up to assess the impact of coastal climate on environmental limiting factors. MODerate Resolution Imaging Spectroradiometer (MODIS) based yearly Gross Primary Production (GPP) and NPP product MOD17 was also tested with LUE based results with standard model validation statistics: Root Mean Square of Error (RMSE), Mean Absolute Error (MEA), Bias, Coefficient of Variation (CV) and Coefficient of Determination (R2). The performance of CASA NPP was tested with the ground based NPP with R2 = 0.89 RMSE = 3.28 P = 0.01. Among the all adopted models, EC

  1. Reduced uncertainty of regional scale CLM predictions of net carbon fluxes and leaf area indices with estimated plant-specific parameters

    Science.gov (United States)

    Post, Hanna; Hendricks Franssen, Harrie-Jan; Han, Xujun; Baatz, Roland; Montzka, Carsten; Schmidt, Marius; Vereecken, Harry

    2016-04-01

    Reliable estimates of carbon fluxes and states at regional scales are required to reduce uncertainties in regional carbon balance estimates and to support decision making in environmental politics. In this work the Community Land Model version 4.5 (CLM4.5-BGC) was applied at a high spatial resolution (1 km2) for the Rur catchment in western Germany. In order to improve the model-data consistency of net ecosystem exchange (NEE) and leaf area index (LAI) for this study area, five plant functional type (PFT)-specific CLM4.5-BGC parameters were estimated with time series of half-hourly NEE data for one year in 2011/2012, using the DiffeRential Evolution Adaptive Metropolis (DREAM) algorithm, a Markov Chain Monte Carlo (MCMC) approach. The parameters were estimated separately for four different plant functional types (needleleaf evergreen temperate tree, broadleaf deciduous temperate tree, C3-grass and C3-crop) at four different sites. The four sites are located inside or close to the Rur catchment. We evaluated modeled NEE for one year in 2012/2013 with NEE measured at seven eddy covariance sites in the catchment, including the four parameter estimation sites. Modeled LAI was evaluated by means of LAI derived from remotely sensed RapidEye images of about 18 days in 2011/2012. Performance indices were based on a comparison between measurements and (i) a reference run with CLM default parameters, and (ii) a 60 instance CLM ensemble with parameters sampled from the DREAM posterior probability density functions (pdfs). The difference between the observed and simulated NEE sum reduced 23% if estimated parameters instead of default parameters were used as input. The mean absolute difference between modeled and measured LAI was reduced by 59% on average. Simulated LAI was not only improved in terms of the absolute value but in some cases also in terms of the timing (beginning of vegetation onset), which was directly related to a substantial improvement of the NEE estimates in

  2. Drought rapidly diminishes the large net CO2 uptake in 2011 over semi-arid Australia

    Science.gov (United States)

    Ma, Xuanlong; Huete, Alfredo; Cleverly, James; Eamus, Derek; Chevallier, Frédéric; Joiner, Joanna; Poulter, Benjamin; Zhang, Yongguang; Guanter, Luis; Meyer, Wayne; Xie, Zunyi; Ponce-Campos, Guillermo

    2016-11-01

    Each year, terrestrial ecosystems absorb more than a quarter of the anthropogenic carbon emissions, termed as land carbon sink. An exceptionally large land carbon sink anomaly was recorded in 2011, of which more than half was attributed to Australia. However, the persistence and spatially attribution of this carbon sink remain largely unknown. Here we conducted an observation-based study to characterize the Australian land carbon sink through the novel coupling of satellite retrievals of atmospheric CO2 and photosynthesis and in-situ flux tower measures. We show the 2010–11 carbon sink was primarily ascribed to savannas and grasslands. When all biomes were normalized by rainfall, shrublands however, were most efficient in absorbing carbon. We found the 2010–11 net CO2 uptake was highly transient with rapid dissipation through drought. The size of the 2010–11 carbon sink over Australia (0.97 Pg) was reduced to 0.48 Pg in 2011–12, and was nearly eliminated in 2012–13 (0.08 Pg). We further report evidence of an earlier 2000–01 large net CO2 uptake, demonstrating a repetitive nature of this land carbon sink. Given a significant increasing trend in extreme wet year precipitation over Australia, we suggest that carbon sink episodes will exert greater future impacts on global carbon cycle.

  3. Effects of Grazing on the Net Ecosystem Exchange of Carbon Dioxide in Grassland Ecosystems (Research Review)%放牧对草地生态系统CO2净气体交换影响研究概述

    Institute of Scientific and Technical Information of China (English)

    朱玲玲; 戎郁萍; 王伟光; 马磊

    2013-01-01

    The net ecosystem exchange of carbon dioxide (NEE) between terrestrial ecosystems and atmosphere is a major component of carbon cycle of terrestrial ecosystems called "breathing" of the terrestrial biosphere , and is great concerned in the research of global climate change. Grasslands, as a major component of the terrestrial ecosystems, comprising approximately 40 % of the world's terrestrial surface, is sensitive to climate change. Grazing plays a significant role in the land use and management of grasslands. With the change in global climate, the impacts of different grazing intensities on grazing ecosystems have different ways. In this review, the effects of grazing on the characteristics of NEE in grassland ecosystems are focused in general based on factors in NEE composition and the pathways of grazing effects on NEE in grasslands. Grazing mainly disturbs the soil-vegetation interface of grasslands then affects grassland NEE through the disturbances on 1) plant, including effects on plant community composition, above and below-ground net primary production and litter; 2) soil, including the effects on soil respiration, soil nutrients especially soil carbon and nitrogen, soil temperature and moisture. The pathways of grazing effects on grasslands can also be applied in disturbances such as cultivation and defoliation and is of great importance in the investigating of NEE characters and carbon flux of different grassland ecosystems, particularly grasslands in different land-use, whether in carbon source or sink in certain degrees and their carbon storage capacity.%陆地生态系统与大气之间的CO2净气体交换(net ecosystem exchange of carbon dioxide,NEE)被称为生物圈的呼吸,它是陆地生态系统碳循环的重要组分,是全球气候变化研究的重点.草地生态系统是陆地生态系统的主体,约占陆地表面的40%,是气候变化的敏感区域.放牧是草地生态系统的主要利用方式,伴随着气候变化,放牧利用

  4. A comparison of soil organic carbon stocks in Viking Age and modern land use systems in Denmark

    DEFF Research Database (Denmark)

    Breuning-Madsen, Henrik; Kristensen, J. Aa.; Holst, Mads Kähler

    2013-01-01

    A comparison of the organic matter content in anaerobic soil horizons in burial mounds and the plough layer in modern farmlands offers a unique opportunity to compare the soil organic carbon (SOC) stocks in ancient and modern land use systems and to evaluate the long term carbon sequestration...... ancient sandy soils, loamy soils surrounding the mounds and nation-wide soil surveys representing modern land use systems with low and high inputs of manure. Results show that within the upper 0.28 m of the soil, which is the average depth of present day plough-layers in Denmark, the carbon stock...

  5. Temporal soil organic carbon dynamics following land-use change for lignocellulosic bioenergy production

    Science.gov (United States)

    McClean, Gary; Rowe, Rebecca; Sohi, Saran; Heal, Kate

    2014-05-01

    As the demand for renewable energy crops increases to assist in reducing anthropogenic carbon dioxide (CO2) emissions, the projected future expansion in bioenergy crop production is expected to cause significant land-use change (LUC). It has been reported that lignocellulosic crops such as Miscanthus and willow short rotation coppice (SRC) have the potential to mitigate CO2 emissions through fossil fuel replacement and by soil organic carbon (SOC) accumulation following direct LUC. Many studies have been carried out with the purpose of measuring site-specific changes, however results are often mixed demonstrating both increasing and decreasing carbon (C) stocks over time. Such variation demonstrates the sensitivity of SOC to many factors such as climate, soil texture, previous land-use and initial SOC content. This study examined a chronosequence of ~100 Miscanthus and willow plantations established on arable and grassland across Britain to provide an improved understanding of general effects on temporal SOC dynamics during LUC. Soil was sampled at each site to a depth of 30 cm and SOC stocks assessed over a 14 year time period. For each of the 4 LUCs no significant differences were observed between measured C stocks after 14 years and expected baseline values for land under arable and grassland management. Evidence will be presented that shows in all cases a 0% change lies within the 95% confidence intervals indicating no true average increase or decrease can be reported for the first 14 years of establishment. Therefore we find no evidence to suggest a short term CO2 mitigation effect provided from SOC storage following the establishment of Miscanthus or willow on arable or grassland. However, longer term measurements are required to assess SOC dynamics beyond this initial period.

  6. Simulated carbon emissions from land-use change are substantially enhanced by accounting for agricultural management

    DEFF Research Database (Denmark)

    Pugh, T. A. M.; Arneth, A.; Olin, S.;

    2015-01-01

    quantified at the global scale. Here we assess the effect of representing agricultural land management in a dynamic global vegetation model. Accounting for harvest, grazing and tillage resulted in cumulative E LUC since 1850 ca. 70% larger than in simulations ignoring these processes, but also changed...... the timescale over which these emissions occurred and led to underestimations of the carbon sequestered by possible future reforestation actions. The vast majority of Earth system models in the recent IPCC Fifth Assessment Report omit these processes, suggesting either an overestimation in their present...

  7. Ecosystem-groundwater interactions under changing land uses: Linking water, salts, and carbon across central Argentina

    Science.gov (United States)

    Jobbagy, E. G.; Nosetto, M. D.; Santoni, C. S.; Jackson, R. B.

    2007-05-01

    Although most ecosystems display a one-way connection with groundwater based on the regulation of deep water drainage (recharge), this link can become reciprocal when the saturated zone is shallow and plants take up groundwater (discharge). In what context is the reciprocal link most likely? How is it affected by land use changes? Has it consequences on salt and carbon cycling? We examine these questions across a precipitation gradient in the Pampas and Espinal of Argentina focusing on three vegetation change situations (mean annual rainfall): afforestation of humid (900-1300 mm) and subhumid grassland (700-900 mm/yr of rainfall), annual cultivation of subhumid grasslands (700-800 mm/yr), and annual cultivation of semiarid forests (500-700 mm). Humid and subhumid grasslands have shallow (salinity of tree species. Cultivation with corn and soybean can lead to groundwater consumption in the driest belt of subhumid grassland. Up to five-fold yield increases in lowlands vs. uplands during the driest years indicate a dramatic impact of groundwater use on carbon uptake and groundwater salinization suggests a recharge-to- discharge switch. In dry forests groundwater is not accessible (> 15 m deep) and recharge under natural conditions is null. The establishment of crops, however, triggers the onset of recharge, as evidenced by vadose zones getting wetter and leached of atmospheric chloride. Cropping may cause water table raises leading to a two-way coupling of ecosystems and groundwater in the future, as it has been documented for similar settings in Australia and the Sahel. In the Pampas land use change interacts with groundwater consumption leading to higher carbon uptake (humid and subhumid grasslands) and salt accumulation (subhumid grasslands). In the Espinal (semiarid forest) land use change currently involves a one-way effect on groundwater recharge that may switch to a reciprocal connection if regional water table raises occur. Neglecting the role of groundwater

  8. Spatial 3D distribution of soil organic carbon under different land use types.

    Science.gov (United States)

    Amirian Chakan, A; Taghizadeh-Mehrjardi, R; Kerry, R; Kumar, S; Khordehbin, S; Yusefi Khanghah, S

    2017-03-01

    Soil organic carbon (SOC) has been assessed in three dimension (3D) in several studies, but little is known about the combined effects of land use and soil depth on SOC stocks in semi-arid areas. This paper investigates the 3D distribution of SOC to a depth of 1 m in a 4600-ha area in southeastern Iran with different land uses under the irrigated farming (IF), dry farming (DF), orchards (Or), range plants on the Gachsaran formation (RaG), and range plants on a quaternary formation (RaQ). Predictions were made using the artificial neural networks (ANNs), regression trees (RTs), and spline functions with auxiliary covariates derived from a digital elevation model (DEM), the Landsat 8 imagery, and land use types. Correlation analysis showed that the main predictors for SOC in the topsoil were covariates derived from the imagery; however, for the lower depths, covariates derived from both the DEM and imagery were important. ANNs showed more efficiency than did RTs in predicting SOC. The results showed that 3D distribution of SOC was significantly affected by land use types. SOC stocks of soils under Or and IF were significantly higher than those under DF, RaG, and RaQ. The SOC below 30 cm accounted for about 59% of the total soil stock. Results showed that depth functions combined with digital soil mapping techniques provide a promising approach to evaluate 3D SOC distribution under different land uses in semi-arid regions and could be used to assess changes in time to determine appropriate management strategies.

  9. RESTORING SUSTAINABLE FORESTS ON APPALACHIAN MINED LANDS FOR WOOD PRODUCTS, RENEWABLE ENERGY, CARBON SEQUESTRATION, AND OTHER ECOSYSTEM SERVICES

    Energy Technology Data Exchange (ETDEWEB)

    Jonathan Aggett

    2003-12-15

    The overall purpose of this project is to evaluate the biological and economic feasibility of restoring high-quality forests on mined land, and to measure carbon sequestration and wood production benefits that would be achieved from forest restoration procedures. In this segment of work, our goal was to review methods for estimating tree survival, growth, yield and value of forests growing on surface mined land in the eastern coalfields of the USA, and to determine the extent to which carbon sequestration is influenced by these factors. Public Law 95-87, the Surface Mining Control and Reclamation Act of 1977 (SMCRA), mandates that mined land be reclaimed in a fashion that renders the land at least as productive after mining as it was before mining. In the central Appalachian region, where prime farmland and economic development opportunities for mined land are scarce, the most practical land use choices are hayland/pasture, wildlife habitat, or forest land. Since 1977, the majority of mined land has been reclaimed as hayland/pasture or wildlife habitat, which is less expensive to reclaim than forest land, since there are no tree planting costs. As a result, there are now hundreds of thousands of hectares of grasslands and scrublands in various stages of natural succession located throughout otherwise forested mountains in the U.S. A literature review was done to develop the basis for an economic feasibility study of a range of land-use conversion scenarios. Procedures were developed for both mixed hardwoods and white pine under a set of low product prices and under a set of high product prices. Economic feasibility is based on land expectation values. Further, our review shows that three types of incentive schemes might be important: (1) lump sum payment at planting (and equivalent series of annual payments); (2) revenue incentive at harvest; and (3) benefit based on carbon volume.

  10. Variability of Total Below Ground Carbon Allocation amongst Common Agricultural Land Management Practices: a Case Study

    Science.gov (United States)

    Wacha, K. M.; Papanicolaou, T.; Wilson, C. G.

    2010-12-01

    Field measurements and numerical models are currently being used to estimate quantities of Total Belowground Carbon Allocation (TBCA) for three representative land uses, viz. corn, soybeans, and prairie bromegrass for CRP (Conservation Reserve Program) of an agricultural Iowa sub-watershed, located within the Clear Creek Watershed (CCW). Since it is difficult to measure TBCA directly, a mass balance approach has been implemented to estimate TBCA as follows: TBCA = FS + FE+ Δ(CS + CR + CL) - FA , where the term Fs denotes soil respiration; FE is the carbon content of the eroded/deposited soil; ΔCS, ΔCR, ΔCL denote the changes in carbon content of the mineral soil, plant roots, and litter layer, respectively; and FA is the above ground litter fall of dead plant material to the soil. The terms are hypothesized to have a huge impact on TBCA within agricultural settings due to intensive tillage practices, water-driven soil erosion/deposition, and high usage of fertilizer. To test our hypothesis, field measurements are being performed at the plot scale, replicating common agricultural land management practices. Soil respiration (FS) is being measured with an EGM-4 CO2 Gas Analyzer and SRC-1 Soil Respiration Chamber (PP Systems), soil moisture and temperature are recorded in the top 20 cm for each respective soil respiration measurement, and litter fall rates (FA) are acquired by collecting the residue in a calibrated pan. The change in carbon content of the soil (ΔCS), roots (ΔCR) and litter layer (ΔCL) are being analyzed by collecting soil samples throughout the life cycle of the plant. To determine the term FE for the three representative land management practices, a funnel collection system located at the plot outlet was used for collecting the eroded material after natural rainfall events. Field measurements of TBCA at the plot scale via the mass balance approach are used to calibrate the numerical agronomic process model DAYCENT, which simulates the daily

  11. Impacts of climate mitigation strategies in the energy sector on global land use and carbon balance

    Science.gov (United States)

    Engström, Kerstin; Lindeskog, Mats; Olin, Stefan; Hassler, John; Smith, Benjamin

    2017-09-01

    Reducing greenhouse gas emissions to limit damage to the global economy climate-change-induced and secure the livelihoods of future generations requires ambitious mitigation strategies. The introduction of a global carbon tax on fossil fuels is tested here as a mitigation strategy to reduce atmospheric CO2 concentrations and radiative forcing. Taxation of fossil fuels potentially leads to changed composition of energy sources, including a larger relative contribution from bioenergy. Further, the introduction of a mitigation strategy reduces climate-change-induced damage to the global economy, and thus can indirectly affect consumption patterns and investments in agricultural technologies and yield enhancement. Here we assess the implications of changes in bioenergy demand as well as the indirectly caused changes in consumption and crop yields for global and national cropland area and terrestrial biosphere carbon balance. We apply a novel integrated assessment modelling framework, combining three previously published models (a climate-economy model, a socio-economic land use model and an ecosystem model). We develop reference and mitigation scenarios based on the narratives and key elements of the shared socio-economic pathways (SSPs). Taking emissions from the land use sector into account, we find that the introduction of a global carbon tax on the fossil fuel sector is an effective mitigation strategy only for scenarios with low population development and strong sustainability criteria (SSP1 Taking the green road). For scenarios with high population growth, low technological development and bioenergy production the high demand for cropland causes the terrestrial biosphere to switch from being a carbon sink to a source by the end of the 21st century.

  12. Impacts of climate mitigation strategies in the energy sector on global land use and carbon balance

    Directory of Open Access Journals (Sweden)

    K. Engström

    2017-09-01

    Full Text Available Reducing greenhouse gas emissions to limit damage to the global economy climate-change-induced and secure the livelihoods of future generations requires ambitious mitigation strategies. The introduction of a global carbon tax on fossil fuels is tested here as a mitigation strategy to reduce atmospheric CO2 concentrations and radiative forcing. Taxation of fossil fuels potentially leads to changed composition of energy sources, including a larger relative contribution from bioenergy. Further, the introduction of a mitigation strategy reduces climate-change-induced damage to the global economy, and thus can indirectly affect consumption patterns and investments in agricultural technologies and yield enhancement. Here we assess the implications of changes in bioenergy demand as well as the indirectly caused changes in consumption and crop yields for global and national cropland area and terrestrial biosphere carbon balance. We apply a novel integrated assessment modelling framework, combining three previously published models (a climate–economy model, a socio-economic land use model and an ecosystem model. We develop reference and mitigation scenarios based on the narratives and key elements of the shared socio-economic pathways (SSPs. Taking emissions from the land use sector into account, we find that the introduction of a global carbon tax on the fossil fuel sector is an effective mitigation strategy only for scenarios with low population development and strong sustainability criteria (SSP1 Taking the green road. For scenarios with high population growth, low technological development and bioenergy production the high demand for cropland causes the terrestrial biosphere to switch from being a carbon sink to a source by the end of the 21st century.

  13. Implementation of dynamic crop growth processes into a land surface model: evaluation of energy, water and carbon fluxes under corn and soybean rotation

    Directory of Open Access Journals (Sweden)

    Y. Song

    2013-06-01

    Full Text Available Worldwide expansion of agriculture is impacting Earth's climate by altering the carbon, water and energy fluxes, but climate in turn is impacting crop production. To study this two-way interaction and its impact on seasonal dynamics of carbon, water and energy fluxes, we implemented dynamic crop growth processes into a land surface model, the Integrated Science Assessment Model (ISAM. In particular, we implement crop specific phenology schemes, which account for light, water, and nutrient stresses while allocating the assimilated carbon to leaf, root, stem and grain pools; dynamic vegetation structure growth, which better simulate the LAI and canopy height; dynamic root distribution processes in the soil layers, which better simulate the root response of soil water uptake and transpiration; and litter fall due to fresh and old dead leaves to better represent the water and energy interception by both stem and brown leaves of the canopy during leaf senescence. Observational data for LAI, above and below ground biomass, and carbon, water and energy fluxes were compiled from two Ameri-Flux sites, Mead, NE and Bondville, IL, to calibrate and evaluate the model performance under corn (C4-soybean (C3 rotation system over the period 2001–2004. The calibrated model was able to capture the diurnal and seasonal patterns of carbon assimilation, water and energy fluxes under the corn-soybean rotation system at these two sites. Specifically, the calculated GPP, net radiation fluxes at the top of canopy and latent heat fluxes compared well with observations. The largest bias in model results is in sensible heat flux (H for corn and soybean at both sites. With dynamic carbon allocation and root distribution processes, model simulated GPP and latent heat flux (LH were in much better agreement with observation data than for the without dynamic case. Modeled latent heat improved by 12–27% during the growing season at both sites, leading to the improvement in

  14. RESTORING SUSTAINABLE FORESTS ON APPALACHIAN MINED LANDS FOR WOOD PRODUCTS, RENEWABLE ENERGY, CARBON SEQUESTRATION, AND OTHER ECOSYSTEM SERVICES

    Energy Technology Data Exchange (ETDEWEB)

    J. Burger; J. Galbraith; T. Fox; G. Amacher; J. Sullivan; C. Zipper

    2003-12-18

    The overall purpose of this project is to evaluate the biological and economic feasibility of restoring high-quality forests on mined land, and to measure carbon sequestration and wood production benefits that would be achieved from forest restoration procedures. In this quarterly report, we present a preliminary comparison of the carbon sequestration benefits for two forest types used to convert abandoned grasslands for carbon sequestration. Annual mixed hardwood benefits, based on total stand carbon volume present at the end of a given year, range from a minimum of $0/ton of carbon to a maximum of $5.26/ton of carbon (low prices). White pine benefits based on carbon volume range from a minimum of $0/ton of carbon to a maximum of $18.61/ton of carbon (high prices). The higher maximum white pine carbon payment can primarily be attributed to the fact that the shorter rotation means that payments for white pine carbon are being made on far less cumulative carbon tonnage than for that of the long-rotation hardwoods. Therefore, the payment per ton of white pine carbon needs to be higher than that of the hardwoods in order to render the conversion to white pine profitable by the end of a rotation. These carbon payments may seem appealingly low to the incentive provider. However, payments (not discounted) made over a full rotation may add up to approximately $17,493/ha for white pine (30-year rotation), and $18,820/ha for mixed hardwoods (60-year rotation). The literature suggests a range of carbon sequestration costs, from $0/ton of carbon to $120/ton of carbon, although the majority of studies suggest a cost below $50/ ton of carbon, with van Kooten et al. (2000) suggesting a cutoff cost of $20/ton of carbon sequestered. Thus, the ranges of carbon payments estimated for this study fall well within the ranges of carbon sequestration costs estimated in previous studies.

  15. A model based investigation of the relative importance of CO2-fertilization, climate warming, nitrogen deposition and land use change on the global terrestrial carbon