TEMPORAL VARIATIONS OF CO2 AND ITS CARBON AND OXYGEN ISOTOPIC RATIOS IN A COOL-TEMPERATE ...
Description:
Using discrete air
sampling, atmospheric CO2 and its stable carbon (d13C) and oxygen (d18O) isotopic ratios have been measured since 1994 in a
cool-temperate deciduous forest in central Japan influenced strongly by the
Asian monsoon. In this paper, the results are shown and the temporal variations
on different time scales are discussed.
Author's Names: S. Murayama, N. Saigusa, S. Yamamoto, C. Takamura, et al
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THE POTENTIAL FOR WIDESPREAD, THRESHOLD DIEBACK OF FORESTS IN NORTH AMERICA UNDER RAPID GLOBAL ...
Description:
The
MC1 Dynamic General Vegetation Model (DGVM) was used to assess the impacts of
global warming on North American ecosystems, north of Mexico, under 6 future climate
scenarios (3 General Circulation Models X 2 emission scenarios). The simulations were begun in 1900 using
observed climate and CO2 until 2000, then transferring to the future
scenarios to 2100. Carbon sequestration
over the continent occurred in the late 20th century and for a short
period into the 21st century, being fostered largely by increased
precipitation, enhanced water-use efficiency and mild temperature
increases. However, these ‘greening’
processes were overtaken by the exponential effects of increasing temperature
on evaporative demand and respiration, producing a subsequent decline. Simulation
experiments suggested that fire suppression could significantly mitigate the
carbon losses, yet many ecosystems were still forced to a lower carrying
capacity.
Author's Names: R.P. Neilson, J.M. Lenihan, D. Bachelet, et al
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THE EFFECTS OF NITROGEN ADDITION ON THE BELOWGROUND CARBON CYCLE IN TEMPERATE FORESTS AND DESERT
Description: Human activities such as fossil fuel and
fertilizer-use have doubled the amount of biologically active nitrogen entering
ecosystems each year [Vitousek et al.,
1997]. N is the limiting nutrient in many ecosystems
and N availability has been shown to affect plant, root, and soil
respiration. For several temperate
forests, experimental addition of N is associated with a decline in soil CO2
efflux [Bowden et al.,
2004; Burton et al., 2004; Nohrstedt et al., 1989; Swanston et al., 2004]. This decline
could be due to either (1) decreased allocation of C to root metabolism and
growth because N demand of plants can be met with less energy expended
belowground, or (2) decomposition rate due to changes in leaf or root tissue
chemistry, or to changes in the decomposer community. In contrast, the few studies of more water
limited systems do not show decreased soil respiration fluxes [Schaeffer et
al., 2003; Verburg et al., 2004], which could reflect hydrologic control of
belowground C allocation.
Author's Names: N.S. Nowinski, S.E. Trumbore, E.B. Allen, et al
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THE AMAZON AND THE MODERN CARBON CYCLE
Description:
Is
the massive Amazon forest a CO2 sink, a source or is it in
equilibrium?
There
is a large uncertainty in carbon fluxes estimates for the tropics as a whole
and in particular for the Amazon region in South America,
bringing the attention to the lack of information to call the region a carbon
source or sink. The production of scientific consistent and long term data
series for the region is a process that has to advance step by step.
Author's Names: J.P.H.B. Ometto, A. D. Nobre, H. R. Rocha, P. Artaxo, et al
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THE INFLUENCE OF THE NAO ON THE CONTINENTAL SHELF PUMP ON THE NORTHWEST-EUROPEAN SHELF
Description:
Using a coupled 3D
hydrodynamic-biogeochemical model system for the Northwest-European shelf we
simulated the years 1993-96, which exhibit an extremely strong transition from
a NAOI-high to a NAOI-low regime. The induced temperature-shift had two
consequences for the carbon budget of the North Sea:
Firstly it increased the CO2 solubility and secondly it destabilized
the water column in spring 1996. The latter effect was the precondition for
mixing events which brought new nitrogen for primary production into the upper
layer. Consequently the air-sea flux was 540 Gmol C a-1 in 1996, the
NAOI-low year, and it was 203 Gmol C a-1 in 1995, the year with the
highest NAOI.
Author's Names: J. Paetsch, W. Kuehn, A.V. Borges, Y. Bozec, et al
Filesize: 16.39 Kb
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SUBCONTINENTAL SCALE SOURCE SINK INVERSION OF ATMOSPHERIC CO2 AND INTERANNUAL VARIABILITY IN ...
Description: A
Time Dependent Inverse (TDI) model is used to estimate CO2 fluxes
for 64 regions of the globe from atmospheric data in the period January
1988–December 2001. These estimated are then used for understanding interannual
variability in fluxes and simulating the CO2 concentrations at
various sites. The NIES/FRCGC transport model driven by interannually varying
meteorology is used in both part of the analysis. Estimated atmospheric CO2
concentrations agree closely with those observed at various sites globally.
Author's Names: P.K. Patra, T. Nakazawa, S. Maksyutov, and T. Takahashi
Filesize: 145.17 Kb
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CARBON, WATER AND LAND USE IN THE WESTERN GREAT PLAINS: MANAGEMENT IMPACTS ON LOCAL AND REGIONAL ...
Description:
This
research investigates how land use in the shortgrass steppe of eastern
Colorado impacts short
and long-term water, carbon and energy dynamics. A large and
homogeneous area of Conservation
Reserve Program (CRP) grassland near Briggsdale, Colorado, was selected
for this
experiment and divided into three 40 hectare plots. An open-path eddy
flux
system was established in each plot and measurements made during a
baseline
comparison prior to land use transformation.
The three treatments include an un-grazed grassland (control), a
moderate intensity grazing treatment, and a dry-land agricultural
rotation
(winter wheat-hay millet; considered optimal for this low rainfall area
of Colorado). We report on the trajectories of carbon,
water and energy fluxes in theses three land use systems and analyze
how
altered carbon storage and water use efficiency may impact short-term
land
surface-atmosphere interactions, as well as long-term source-sink
relationships, water conservation, productivity and sustainability.
Author's Names: N.P. Hanan, T.C. Peterson, and C.A. Williams
Filesize: 71.47 Kb
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TOWARDS A NEW UNDERSTANDING OF RECENT CARBON CYCLE VARIABILITY COMBINING ATMOSPHERIC INVERSION, ...
Description:
We present a comprehensive
analysis of the recent inter-annual variation of the atmospheric CO2
growth rate, with a special focus on the 2002-2003 period, using a state of the
art atmospheric inversion, process driven model simulations (land and ocean),
and recent biomass burning estimates. The inverse estimates compare favourably well
with the model simulations over North Asia and
indicate a large contribution of the fire anomaly to the total anomaly, for
that region in 2003. Over Europe, the spatial distribution of the inverse and
bottom-up flux anomalies for 2003 have similarities but the time evolution of
the total fluxes still need to be reconciled.
Author's Names: P. Peylin, N. Viovy, C. Carouge, et al
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MODELING DROUGHT TOLERANCE IN AMAZONIA WITH SiB3
Description:
The
Amazon region of South America plays a
significant role in global cycles of water, energy and carbon, yet it
is also
one of the most challenging biogeographical areas of the world to model
correctly. Numerous global climate models have problems with anomalous
die-back
of the Amazon rain forest variously attributed to inadequate
representation of
rainfall, faulty soil moisture dynamics or an inability to correctly
simulate
the drought tolerance of the vegetation. Such misrepresentation of the
Amazon
in global climate models can cause larger than observed excursions of
the
global carbon cycle. This poster explores soil moisture and drought
stress for Amazonia with the Simple Biosphere Model (SiB3) and
possible reasons and solutions to the rain-forest die back problem,
which
should lead to more reasonable estimates of carbon fluxes at the
ecosystem
scale.
Author's Names: L. Prihodko, A.S. Denning, and I. Baker
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FUTURE EVOLUTION OF THE TERRESTRIAL CARBON CYCLE CONSTRAINED BY CURRENT OBSERVATIONS: RESULTS ...
Description:
In a Carbon Cycle Data Assimilation System (CCDAS) one
infers the values of the parameters controlling the function of a process model
using various observations. One can then calculate quantities of interest from
the optimized parameters and the model. One can also calculate the
uncertainties on the parameters and propagate these to uncertainties of the
calculated quantities. In Rayner et al. [2005] we assimilated atmospheric
observations over two decades, into a terrestrial model and calculated fluxes
over this period. Here we extend this work by calculating the response of the calibrated
terrestrial biosphere to a GCM simulation of future climate. Using this
combination we are able to comment on the fate of terrestrial carbon pools and
fluxes under climate change, calculate the uncertainties of the response, and
determine which parameters in the model are responsible for this uncertainty.
We include an extra parameter that scales the climate change signal from the
GCM projection. We thus extend the sensitivity and uncertainty analysis to
include the climate sensitivity.
Author's Names: P. Rayner, M. Scholze, P. Friedlingstein, et al
Filesize: 12.32 Kb
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