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Category: Main/Abstracts/Land Use and the Terrestrial Carbon Cycle


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  THE AGE OF CARBON RESPIRED FROM TERRESTRIAL ECOSYSTEMS  Popular
Description:

Carbon enters ecosystems through a single process, photosynthesis, and nearly all is returned to the atmosphere through respiration, some 50-80% of which occurs below-ground. Soil (belowground) respiration integrates CO2 derived from C that has resided in the ecosystem for periods of differing duration, ranging from relatively recent photosynthetic products that fuel root metabolism, to CO2 derived from decomposition of plant and soil organic matter that may be decades to centuries old.  A comparison of the radiocarbon content of CO2 respired by roots, microbes, and soils with the record of radiocarbon in atmospheric CO2 allows direct estimation of the mean age of C being respired [Trumbore 2000; Wang et al. 2000, Cisneros Dozal et al. 2005; Borken et al. 2005]. 


Author's Names: S.E. Trumbore, E.A Schuur, E. A. Davidson, PB Camargo, et al
Filesize: 21.45 Kb
Added on: 08-Aug-2005 Downloads: 156
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  THE CANADIAN TERRESTRIAL ECOSYSTEM MODEL (CTEM) – THE TERRESTRIAL CARBON CYCLE COMPONENT OF THE .. 
Description:

The Canadian Centre for Climate Modelling and Analysis (CCCma) is currently working towards development of a coupled carbon climate model in which the time-evolving atmospheric concentrations of greenhouse gases, and in particular CO2, are computed prognostically on the basis of scenario-specific emissions. The Canadian Model for Ocean Carbon (CMOC) and the Canadian Terrestrial Ecosystem Model (CTEM) are the oceanic and terrestrial carbon cycle models implemented in this coupled framework. This presentation will focus on the terrestrial carbon cycle component CTEM that is able to grow vegetation from bare ground and includes processes of photosynthesis, autotrophic and heterotrophic respiration, phenology, allocation, mortality, land use change, fire, and competition between plant functional types (PFTs). In the coupled model CTEM provides a dynamic land surface interface to the climate model by simulating time-varying vegetation structural attributes as a function of model climate and provides net fluxes of CO2 between the land surface and the atmosphere. This presentation provides an overview of how the primary terrestrial ecosystem processes are modeled in CTEM. It also discusses in some detail the parameterizations of fire and competition among plant functional types (PFTs). These two processes have not received adequate attention in the current generation of dynamic global vegetation models. The fire module of CTEM takes into account all three aspects of the fire triangle: fuel availability, readiness of fuel to burn depending on weather conditions, and the presence of an ignition source. The approach also takes into account the anthropogenic effect on natural fire regimes. Competition between PFTs is modeled on the basis of a modified form of Lotka-Volterra equations that, unlike existing applications, allows coexisting PFTs. Model results at selected locations show that CTEM estimates of vegetation biomass, leaf area index, fire return interval, biomass burning CO2 emissions and fractional coverages of coexisting PFTs compare reasonably well with observation-based estimates.


Author's Names: Vivek Arora
Filesize: 32.82 Kb
Added on: 25-Jul-2005 Downloads: 45
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  THE EFFECTS OF LAND USE CHANGE AND OF SEASONAL VARIATIONS IN CLIMATE ON GPP ACROSS THE ... 
Description:

Amazonian forests play an important and complex role in the global carbon cycle, contributing substantially to increases (via land use change emissions) and possibly to net sequestration (in intact forests) of atmospheric CO2. Predicting these processes of net carbon uptake and release depends crucially on understanding ecosystem response to both seasonal and interannual variations. However, prominent ecosystem modeling studies of the Amazonian carbon cycle [Tian et al., 1998; Botta 2002] appear to make seasonal predictions (wet-season carbon uptake and dry-season loss) at odds with both some site-specific observations (which show the opposite pattern, Saleska et al., [2003]) and basin-wide satellite observations (which imply large-scale increases in the activity of photosynthetic vegetation during the dry season, Huete et al., [2005]).


Author's Names: S. R. Saleska, M. Pathmadevan, A. Huete, F. Cardoso, et al
Filesize: 19.68 Kb
Added on: 04-Aug-2005 Downloads: 28
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  THE IMPACT OF CLOUDS ON ECOSYSTEM CO18O ISOFLUXES IN THE GREAT PLAINS  Popular
Description:

Mechanistic explanations for the downward excursion in d18O of atmospheric CO2 observed during the mid-1990s and the generally large interannnual variability characteristic of this isotopologue are lacking. We hypothesize that the excursion and related variations in d18O of atmospheric CO2 may be linked to global-scale variations in cloud cover. However, very little is known about the influence of clouds on biosphere-atmosphere CO18O exchanges. Recent work has demonstrated the influence of boundary layer clouds on canopy photosynthesis through increases in the diffuse radiation fraction and relative humidity, combined with decreases in leaf temperature. In concert, these alterations tend to increase canopy photosynthesis and conductance, which should also increase CO18O isofluxes. However, photosynthetic CO18O isofluxes also depend critically on the d18O of leafwater, and enhanced cloudiness typically decreases the d18O of leafwater by enhancing relative humidity and water vapor exchange across stomata. Thus, the net impact of differing cloud regimes on biosphere-atmosphere CO18O exchanges is difficult to predict. Preliminary simulations suggest a large impact of diffuse radiation on canopy photosynthesis by increasing the flux from shade leaves. The impact of this effect on biosphere-atmosphere CO18O exchanges is diluted somewhat by the lower enrichment in leafwater d18O on cloudy days with high diffuse radiation fractions. Our results suggest that these effects are very dependent on LAI and photosynthetic pathway (C3 or C4).


Author's Names: C.J. Still, W.J. Riley, S.C. Biraud, D. Noone, et al
Filesize: 206.00 Kb
Added on: 08-Aug-2005 Downloads: 121
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  THE MEASUREMENT OF CO2 EFFLUX ON FOREST FLOOR IN DECIDUOUS FOREST, JAPAN - THE CASE IN THE DEEP ... 
Description:

For more than 1000 years, the forests in mountainous areas of Japan have been distinguished by excessive harvesting and litter collection. Revegetation of these areas over the past 130 years has resulted in the current forest coverage. However, the forest soils are immature and contain very little organic carbon. Therefore, the past human impact likely affects the present carbon cycle and CO2 efflux at the forest floor. It is important to estimate the carbon cycle and CO2 efflux at the forest floor in such a heavily affected ecosystem to discuss the relationship between the carbon cycle and land use management. Therefore, we measured the CO2 efflux at the forest floor in a deciduous forest heavily affected by human activities in Japan and estimated the annual rate.


Author's Names: K. Tamai, Y. Kominami, T. Miyama, Y. Goto and Y. Ohtani
Filesize: 181.85 Kb
Added on: 08-Aug-2005 Downloads: 26
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  THE ROLE OF ROOT RESPIRATION IN TEMPERATE DECIDUOUS FOREST IN CENTRAL JAPAN 
Description:

To evaluate the role of root respiration (Rr), we measured spatial and temporal variation of Rr. We measured root biomass, Rr and soil respiration (Rs) in temperature deciduous forest in central Japan. The size dependence of Rr was shown and Rr in fine root (< 2 mm) accounted more than half of total Rr per unit area. Moreover, we had measured continuously Rr and Rs using automated system. Rr responded exponentially to soil temperature. High soil moisture during and just after rainfall caused limiting factor in Rr. And the contribution of Rr to Rs changed seasonally.


Author's Names: M. Dannoura, Y. Kominami , K. Tamai, M. Jomura, et al
Filesize: 63.08 Kb
Added on: 28-Jul-2005 Downloads: 25
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  THE UNDERPINNINGS OF LAND-USE HISTORY: THREE CENTURIES OF GLOBAL GRIDDED LAND-USE ...  Popular
Description:
To accurately assess the impacts of human land-use on the Earth System, information is needed on the current and historical patterns of land-use activities. Previous global studies have focused on developing reconstructions of the spatial patterns of agriculture. Here, we provide the first global gridded estimates of the underlying land conversions (land-use transitions), wood harvesting, and resulting secondary lands annually, for the period 1700-2000. For input, we used two existing datasets of global gridded land-use history—HYDE [Klein Goldewijk 2001] and SAGE [Ramankutty & Foley 1999], a new reconstruction of national wood harvest that we spatially disaggregated to a global gridded product, and model estimates of the spatial distribution of plant carbon density and its recovery. Since these do not fully constrain the problem, we added assumptions related to four additional factors: the residence time of agricultural land, the inclusiveness of wood harvest statistics, the priority for land conversion and logging (e.g. primary- or secondary-land), and the spatial pattern of wood harvest within countries. In order to estimate uncertainty and characterize model sensitivity, a set of 216 alternative reconstructions was derived using different assumptions. We estimate that the accumulated global wood harvest 1700-2000 was approximately 112 Pg C including slash.

Author's Names: G.C. Hurtt, S. Frolking, M.G. Fearon, B. Moore III, et al
Filesize: 17.49 Kb
Added on: 29-Jul-2005 Downloads: 149
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  TOWARDS A BETTER QUANTIFICATION OF CROPLANDS EXTENT AND MANAGEMENT CONTRIBUTION TO CARBON CYCLING 
Description:

The development of agriculture responding to increasing demand for food raises the question of the role of cultivated land in relation to carbon sources and sinks, their spatial patterns and temporal variability.


Author's Names: P.C. Smith, N. Viovy, Y. Meurdesoif, S. Gervois, et al
Filesize: 71.66 Kb
Added on: 04-Aug-2005 Downloads: 19
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  WATERSHED SCALE CHANGE IN THE CARBON AND WATER CYCLES BY FORESTRY ACTIVITIES IN A ... 
Description:

To evaluate the deforestation and forestation effects on the carbon and water cycles, micrometeorological and hydrological observations were conducted in a conifer-broadleaf mixed forest in northernmost Japan in the series of these activities.  The clear-cutting of trees changed the carbon balance of the ecosystem to the net source in the plant-growing period, although the undergrowth, Sasa bamboos, still keeps large biomass after the tree-cutting and the half-hourly flux indicate carbon sequestration in the daytime. Strip-cutting of Sasa bamboos and planting of the larch saplings did not cause the distinct change in the emission rate. On the other hand, the evapotranspiration rate recovered to the same level with that in the mixed forest within 2 years after the clear-cutting. We attributed the increase in the evapotranspiration rate partly to the acclimation in the transpiration capacity of Sasa bamboos.


Author's Names: K. Takagi, M. Nomura, K. Fukuzawa, H. Shibata, et al
Filesize: 122.11 Kb
Added on: 08-Aug-2005 Downloads: 21
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  WEEKLY OBSERVATIONS OF STABLE ISOTOPE COMPOSITION OF ECOSYSTEM-ATMOSPHERE CO2 ... 
Description:

The stable isotope composition of atmospheric CO2 is being monitored in five AmeriFlux sites (four forests and one grassland) by collecting air samples inside and above canopies at weekly intervals. Measurements of concentration, d13C and d18O of atmospheric CO2 have continuously been made from 100-ml flask samples since 2001. These measurements, in concert with eddy covariance flux measurements, provide mechanistic insights relating observed isotope changes and the controls over carbon sequestration and loss on seasonal and interannual bases. Data and a brief project description are available via the Internet at: http://ecophys.biology.utah.edu/Research/DOE_TCP/index.html.


Author's Names: C.-T. Lai, and J.R. Ehleringer
Filesize: 64.92 Kb
Added on: 01-Aug-2005 Downloads: 22
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     Talk History
Friday, September 30
· Discussion Panel
· Nitrogen Regulation of Carbon Sequestration in Terrestrial Ecosystems in Respons
· The Role of Water Relations in Driving Grassland Ecosystem Responses to Rising A
· Unraveling the Decline in High-latitude Surface Ocean Carbonate
Thursday, September 29
· Hazards of Temperature on Food Availability in Changing Environments (HOT-FACE)
· The Amazon and the Modern Carbon Cycle
· New Coupled Climate-carbon Simulations from the IPSL Model
· The Changing Carbon Cycle
· What are the Most Important Factors for Climate-carbon Cycle Coupling?
· CO2 Uptake of the Marine Biosphere
· European-wide Reduction in Primary Productivity Caused by the Heat and Drought i
· Persistence of Nitrogen Limitation over Terrestrial Carbon Uptake
· Atmospheric CO2, Carbon Isotopes, the Sun, and Climate Change over the Last Mill
· Proposing a Mechanistic Understanding of Atmospheric CO2 During the late Pleist
· Greenhouse Gas (CO2, CH4) and Climate Evolution since 650 kyrs Deduced from Anta
Wednesday, September 28
· (In and) Out of Africa: Estimating the Carbon Exchange of a Continent
· Recent Shifts in Soil Dynamics on Growing Season Length, Productivity, and...
· Interannual Variability in the Carbon Exchange Using an Ecosystem-fire Model
· Photosynthesis and Respiration in Forests in Response to Environmental Changes
· Seasonal and Interannual Variability in Net Ecosystem CO2 Exchange in Japan
· Estimating Landscape-level Carbon Fluxes from Tower CO2 Mixing Ratio Measurement
· Monitoring Effects in Climate and Fire Regime on Net Ecosystem Production
· Radiative Forcing from a Boreal Forest Fire
· The Influence of Soil and Water Management on Carbon Erosion and Burial
· Spatial and Temporal Patterns of CO2, CH4, and N2O Fluxes in Ecosystems
· Modeling the History of Terrestrial Carbon Sources and Sinks
· The Age of Carbon Respired from Terrestrial Ecosystems
· Discussion Panel
· The Underpinnings of Land Use History
Tuesday, September 27
· Regional CO2 Fluxes for North America Estimated from NOAA/CMDL Observatories

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The 7th International CO2 Conference

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September 25th - 30th
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