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


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  APPARENT TRENDS IN PHOTOSYNTHETIC CAPACITY OF MONSOON ASIA FROM 1982 TO 2002  Popular
Description:
The rapid economic growth of Monsoon Asia raises concerns about the future of carbon stored in the terrestrial ecosystems of the region, especially in connection with climate change [Tian et al., 2003; Canadell et al., 2002; Oikawa and Ito, 2001; Esser, 1995]. The regional carbon budget for 1980s suggests that Monsoon Asia as a whole acted as source [Tian et al., 2003], although some parts of the region acted as sink. Here we provide some evidence from satellite data that photosynthetic capacity of the region changed in the manner that suggests similar conclusion. Comparing the period 1982-1992 and the period 1992-2002, we found that the photosynthetic capacity of the territory generally decreased in the forest zone and increased in the non-forest zone of the region.

Author's Names: G. A. Alexandrov, T. Oikawa, and Y. Yamagata
Filesize: 39.70 Kb
Added on: 25-Jul-2005 Downloads: 51
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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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  EFFECT OF RESPIRATION AND CANOPY PARAMETERIZATIONS ON MODELED CARBON FLUX 
Description:

Simulations of the global carbon cycle are strongly dependent upon model representations of the exchange of carbon, energy, moisture and momentum between the atmosphere and terrestrial biosphere. The carbon flux produced by these biophysical models is subsequently dependent on the method used to produce respiration and photosynthesis within the model on both spatial and temporal scales. We use an updated version of the Simple Biosphere Model (SiB3) to simulate global carbon flux between atmosphere and land surface, and compare model results to flux tower and flask network observations. SiB3 assumes no annual net source or sink of carbon in each gridcell, but the spatial pattern and seasonality of carbon flux and atmospheric concentration can be strongly influenced by parameterization of heterotrophic and autotrophic respiration and the representation of vegetation phenology.


Author's Names: I.T. Baker, K.M. Schaefer and A.W. Philpott
Filesize: 20.07 Kb
Added on: 25-Jul-2005 Downloads: 41
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  CONTINUOUS IN SITU MEASUREMENTS OF ATMOSPHERIC O2 AND CO2 
Description:

Simultaneous and continuous measurements of O2 and CO2 made in the air around terrestrial ecosystems have the potential to improve our understanding of the biogeochemistry of the ecosystem, and may reduce uncertainties in estimates of terrestrial carbon uptake derived from atmospheric O2 measurements. Following the design of Stephens et al. [2001], we have constructed an instrument that performs continuous in situ measurements of atmospheric O2 and CO2 concentrations. We present design and performance data, along with preliminary results from a deployment at the Environmental Measurement Site at Harvard Forest in central Massachusetts.


Author's Names: M.O. Battle, R. Perry, E. Sofen, J. Carpenter, B.B. Stephens
Filesize: 67.95 Kb
Added on: 25-Jul-2005 Downloads: 39
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  DOWN AND DIRTY: USING A CONTINENTAL, NOT-SO-TALL TOWER TO STUDY TRENDS... 
Description:

Precise CO2 concentration measurements at marine stations and tall towers are crucial for quantifying global trends in atmospheric CO2 concentrations. We propose that measurements in the continental planetary boundary layer—the poor cousin of the clean background stations—can be used to understand trends in, and controls, of atmospheric CO2 concentrations at local and regional scales as well as global scales. The key is choosing appropriate time scales of integration for the data. In the US Southern Great Plains, we are measuring precise CO2 concentrations continuously at 2–60 m and weekly at 300 and 3300 m above ground level (agl). CO2 flux is measured in individual crop fields and pastures (4 m towers) and at 60 m. The precise CO2 concentrations show strong continental influence in both diurnal and seasonal cycles. In continental regions, atmospheric CO2 profiles are strongly influenced by atmospheric dynamics as well as ecosystem and anthropogenic fluxes. Relating site level measurements or atmospheric profiles to regional CO2 budgets requires methods to represent or evaluate these influences. We observe inter-annual differences in the climatology of diurnal cycles (seasonal average diurnal cycles). Using the several years’ data for boundary layer concentrations, the annual trend in CO2 growth nearly matches the value estimated by National Oceanic and Atmospheric Administration (NOAA) Climate Monitoring Diagnostic Laboratory for our latitude band.


Author's Names: M.S. Torn, M.L. Fischer, S.C. Biraud, W.J. Riley, et al
Filesize: 102.88 Kb
Added on: 25-Jul-2005 Downloads: 38
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  SPATIALLY DISTRIBUTED CO2, SENSIBLE, AND LATENT HEAT FLUXES OVER THE SOUTHERN GREAT PLAINS 
Description:

Vegetation strongly influences the spatial distribution of sensible and latent heat fluxes, and also controls ecosystem-atmosphere CO2 exchange. We describe here a methodology to estimate surface energy fluxes and Net Ecosystem Exchange (NEE) of CO2 continuously over the Southern Great Plains, using (1) data from the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program in Oklahoma and Kansas; (2) meteorological forcing data from Mesonet facilities; (3) U.S. Geological Survey (USGS) soil database; (4) MODIS NDVI at 250 meters resolution; and (5) a tested carbon and isotope land-surface model (ISOLSM, based on LSM1.0 [Bonan 1996]). The need for distributed ecosystem modeling was demonstrated by the large spatial variability in CO2 fluxes across the region, which is typically modeled as homogeneous cropland. This work addresses U.S. national goals of estimating regional CO2 sources and sinks, and provides inputs to forward and inverse models.


Author's Names: S.C. Biraud, W.J. Riley, M.L. Fischer, M.S. Torn, J.A. Berry
Filesize: 424.23 Kb
Added on: 26-Jul-2005 Downloads: 34
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  C4 VEGETATION COVERAGE AND PHOTOSYNTHESIS IN SOUTH AMERICA: SEASONAL AND INTERANNUAL VARIATIONS  Popular
Description:

We build upon a previous approach to predict C3 and C4 fractions on the land surface using new higher resolution satellite datasets on vegetation growth form and crop type coverage. The approach relies upon the near-universal restriction of C4 photosynthesis to the herbaceous growth form and the differing performance of C3 and C4 plants in various temperature and radiation regimes. MODIS-derived data provide detailed information on growth form composition (%herbaceous, %woody, and %bare for each grid cell). Precipitation and temperature variations are derived from station data climatologies. Combining these data with MODIS-derived NPP fields from 2001, we predict latitudinal variations in C3 and C4 photosynthesis for South America. These variations will be discussed in the context of the global carbon cycle and the difficulty they pose for interannual inversion studies using global CO2 and d13C atmospheric data. 


Author's Names: C.J. Still1,2, and R. Powell
Filesize: 438.58 Kb
Added on: 08-Aug-2005 Downloads: 79
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  ALLOCATION AND RESIDENCE TIME OF CURRENT PHOTOSYNTHETIC PRODUCTS IN A BOREAL FOREST USING ... 
Description:

We tested the utility of a low-level radiocarbon (14C) pulse-chase label for quantifying carbon allocation patterns and the contributions of different components to total ecosystem respiration at ambient CO2 concentrations in a black spruce forest stand in central Manitoba, Canada.  Approximately .01 moles of CO2 that was isotopically enriched in 14C to ~100,000 times background atmospheric 14C levels was introduced into the headspace of a 37,000 L translucent dome enclosure.  Over a one hour period, ~70% of this label was photosynthetically assimilated by the enclosed vegetation. The label application produced a 14C signature well below regulated health standards, and was easily detectable with Accelerator Mass Spectrometry (AMS).  We followed the allocation and timing of labeled photosynthetic products by measuring the amount and 14C content of CO2 respired from different ecosystem components over the following 30 days.


Author's Names: M.S. Carbone, C.I. Czimczik, K.E. McDuffee, S.E. Trumbore
Filesize: 41.74 Kb
Added on: 27-Jul-2005 Downloads: 46
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  MODELING NET ECOSYSTEM PRODUCTIVITY: SCALE ISSUES AND REGIONAL APPLICATION TO THE IBERIAN PENINSULA 
Description:

Our research goal is to assess the regional vegetation dynamics in the Iberian Peninsula (IP). For this purpose, estimations of net ecosystem production (NEP) from a productivity ecosystem model, the Carnegie Ames Stanford Approach (CASA) model [Potter et al., 1993], were compared with local CO2 flux measurements. The CASA calibration process aimed the tuning of efficiency scalars directly related to net primary productivity and soil respiration calculations: maximum light use efficiency (ε*) and temperature effect on soil fluxes (Q10), respectively. Local weather station data was used for climatic inputs, as well as remotely sensed leaf area index (LAI) and fraction of photosynthetically active radiation (FPAR) from the MODIS TERRA sensor. Firstly, NEP calculations were performed at different temporal resolutions, ranging from monthly to daily time steps, in order to assess the impact of temporal scales on productivity estimates. Both the calibration and validation procedures showed significant confidence, although the main processes behind vegetation carbon fluxes were best simulated at temporal scales ranging from 8 days to monthly. The impact of spatial scale was also analyzed on the NEP estimates. It was found that results accuracy was influenced by the data spatial resolution, and, furthermore, by the tree cover percentage of the aggregated cells. A correction method was implemented and a reduction of the spatial aggregation error up to 10% was obtained. The long term NEP analysis for the IP indicates statistically significant positive trends mainly related to solar radiation positive trends. A less significant negative trend was also found with a strong spatial autocorrelation behavior.


Author's Names: N. Carvalhais, J. Seixas and R. Myneni
Filesize: 67.71 Kb
Added on: 28-Jul-2005 Downloads: 47
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  ESTIMATING LANDSCAPE-LEVEL CARBON FLUXES FROM TOWER CO2 MIXING RATIO DATA  Popular
Description:

Variations of the CO2 mixing ratio in the atmosphere near the surface result from several processes, including photosynthesis and respiration of the underlying ecosystems, vertical mixing near the surface and in the planetary boundary layer (PBL), and entrainment of air above the PBL. We developed a novel approach for isolating ecosystem metabolism signals at the landscape scale (102-104 km2) in an hourly CO2 record using a vertical diffusion scheme coupled with an ecosystem model.


Author's Names: J.M. Chen, B. Chen, K. Higuchi, D. Chan, et al
Filesize: 33.38 Kb
Added on: 28-Jul-2005 Downloads: 145
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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

The Omni Interlocken Resort
September 25th - 30th
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