ESTIMATING THE CO2 FLUX FROM COARSE WOODY DEBRIS USING AUTOMATED AND MANUAL CHAMBER ...
Description: The CO2 flux from coarse woody debris (RCWD) in a deciduous broad-leaved forest was measured
using chamber measurements. The relationships between RCWD
and environmental factors, such as temperature (T)
and the water content (θ) of the
coarse woody debris (CWD), were determined from long-term continuous
measurements. Measurements of the RCWD
of many CWD samples revealed relationships between RCWD
and CWD characteristics, such as wood density (ρ)
and diameter (D).
A field survey conducted in 2003 estimated the mass of
CWD as 9.30tC·ha-1, with snags amounting to 60% of the total CWD
mass. Scaling RCWD to the ecosystem
while considering environmental factors according to the type (snag or log) of
CWD and CWD characteristics, we estimated that the annual RCWD
in the forest was 0.50tC·ha-1·y-1 in 2003. This came to
13-19% of the total heterotrophic respiration in the forest. The mean annual
CWD input mass from 2000 to 2004 was 0.61tC·ha-1·y-1.
Therefore, 0.11tC·ha-1·y-1 were sequestered by CWD, which
amounted to 7% of the net ecosystem production (NEP)
in the forest. In a younger forest, it is difficult to assume that the CWD
input and decomposition are balanced, so the RCWD
and CWD input mass should be quantified to evaluate the forest carbon cycle and
NEP.
Author's Names: M. Jomura, Y. Kominami, K. Tamai, T. Miyama, et al
Filesize: 182.40 Kb
Added on: 29-Jul-2005 Downloads: 33
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HISTORICAL CHANGES IN CARBON STORAGE OF THE EASTERN UNITED STATES: UNCERTAINTIES ASSOCIATED ...
Description: Process-based
models are important tools in assessments because they are able to integrate
mechanisms responsible for changes in carbon storage. Retrospective model
analyses are important for clarifying land use impacts on carbon storage
estimates. The objectives of our study were to: 1) develop a land use model
that allows annual conversion of native ecosystems to agriculture and creation
of age cohorts following harvest and cropland abandonment from 1600 to 2002; 2)
compare modeled age class distribution with independent inventory data on stand
age distributions, and 3) use these data sets to drive the Terrestrial
Ecosystem Model (TEM) and evaluate how assumptions about soil degradation and
CO2 fertilization influence estimates of changes in carbon storage
of the eastern US.
Author's Names: L.A. Joyce, A.D. McGuire, D.P. Coulson, J. Clein, T. Bumside
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EFFECTS OF DISTURBANCE AND CLIMATE CHANGE ON CARBON BALANCE IN CANADA’S FORESTS AND WETLANDS
Description:
Model
simulations indicated that Canada’s
forests and wetlands acted as a carbon (C) sink of 112 Tg C
yr-1 averaged during 1901-1998. Wetlands was a crucial contributor
to this sink (50 Tg C yr-1). Disturbance history determined the decadal temporal pattern of C
balance. Nondisturbance factors enhanced C accumulations in Canada’s forests and
wetlands in the last century. The enhancement of each nondisturbance factor on
C uptake changed temporally.
Author's Names: W. Ju, and J. M. Chen
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MODELING TERRESTRIAL CO2 SOURCES, SINKS, AND ATMOSPHERIC TRANSPORT USING ASSIMILATED ...
Description:
Progress
in determining CO2 sources, sinks, and their response to
environmental forcing will rely on utilization of more extensive and intensive
CO2 and related observations including those from satellite remote
sensing. Full exploitation of new
observations will require new modeling and analysis techniques, especially
those that can use information at finer spatial and temporal scales than has
traditionally been employed in “top-down” carbon flux studies. We report on a modeling effort to reduce
uncertainty in carbon cycle processes that create the so-called missing
terrestrial sink of atmospheric CO2 using transport fields derived
from NASA’s GEOS-4 meteorological assimilation analyses. Our overall objective is to improve
characterization of CO2 source/sink processes globally with improved
formulations for atmospheric transport, terrestrial uptake and release, biomass
and fossil fuel burning, and observational data analysis. We show results from an advanced biosphere
model (SiB3) constrained by remote sensing data and coupled to the global
transport model to produce distributions of CO2 fluxes and
concentrations that are consistent with actual meteorological variability. Use of analyzed meteorological data allows
comparison to observations on a wide range of temporal and spatial scales. Here we compare with local-to-global data for
hourly to annual CO2 simulation.
The results will help to prepare for the use of satellite CO2
and other data in a multi-disciplinary carbon data assimilation system for
analysis and prediction of carbon cycle changes and carbon/climate
interactions.
Author's Names: S.R. Kawa, A.S. Denning, S.L. Conner-Gausepohl, et al
Filesize: 104.98 Kb
Added on: 01-Aug-2005 Downloads: 32
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FLUXES OF CO2, N2O, AND CH4 IN A COLD-TEMPERATE GRASSLAND SOIL OF NORTHERN JAPAN ESTIMATED ...
Description: Concentrations of 222Rn, CO2,
N2O and CH4 were measured in a cold-temperate northern
Japanese grassland soil during 1996 to compare the fluxes of CO2, N2O
and CH4 calculated by the 222Rn method and the static
chamber method and to estimate the source strengths of CO2 and N2O
in the soil using the 222Rn method. The 222Rn fluxes
ranged from 890 to 3400 dpm/m2/h
and the average was 1570±310 dpm/m2/h on sandy soil (50% sand). The
results of CO2, N2O and CH4
flux-measurements by the 222Rn method were in agreement with those
by the static chamber method within the observed range of error. The vertical
profiles of soil source
strengths of CO2
and N2O were also calculated from the concentration
gradients of 222Rn, CO2 and N2O to investigate
seasonal changes in the soil production rates of CO2
and N2O. The production rates of CO2 and N2O
varied significantly by season, averaging 1650±450 mgC/m3/h and
19±3.2 µgN/m3/h, respectively. These seasonal changes in the source
strengths of CO2 and N2O in the surface soil corresponded
with changes in fluxes of CO2 and N2O from the soil.
Author's Names: Yongwon Kim and Noriyuki Tanaka
Filesize: 62.26 Kb
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LONG-TERM OBSERVATION OF CO2 FLUX ABOVE A BROADLEAVED DECIDUOUS FOREST IN SAPPORO, NORTHERN JAPAN
Description:
A long-term observation of CO2 exchange was
conducted above a broadleaved deciduous forest in Sapporo,
northern Japan.
The CO2 exchange was measured using the eddy covariance method with
closed-path gas analyzer and we obtained net ecosystem production (NEP). We estimated a carbon budget using a simple
empirical model. In this model, ecosystem respiration (RE) and gross primary
production (GPP) were parameterized by soil temperature and photosynthetically
active radiation (PAR)
respectively. The annual NEP
derived from an equation “NEP = GPP
-RE” ranged from 237 to 431 g C m-2
year-1 for 4 years (2000 - 2003).
Author's Names: K. Kitamura, Y. Nakai, S. Suzuki, K. Yamanoi, et al
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EDDY-COVARIANCE, CHAMBER AND BIOMETRIC BASED ESTIMATES OF ANNUAL CO2 EXCHANGE ABOVE TEMPERATE ...
Description:
In a temperate deciduous forest in Japan
situated complex terrain, net ecosystem CO2 exchange (NEE) was
estimated using micro-meteorological method, and net ecosystem products (NEP)
was estimated by measures of major carbon pools and fluxes using biometric and
chamber methods. In this study we evaluate the threshold value of u* for
interpolation in case stability was high using estimated NEP acquired by biometric
method. And the function which relate temperature to FCO2 for
interpolation was evaluated by the data acquired using automated chamber for
soil, CWD, trunk and foliage CO2 exchanges. Averaged net uptake of
CO2 measured by eddy covariance method from 1999 to 2002 was 3.4 tC
yr-1 ha-1 without compensation of nighttime underreport.
Increase of live under and above ground biomass from 1994 to 1999 was 1.56 tC
yr-1 ha-1. U* threshold values based on biometric and
chamber NEP were respectively 0.28 and 0.35 m sec-1
Author's Names: Y. Kominami, T. Miyama, K. Tamai, Y. Goto, et al
Filesize: 82.79 Kb
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INVESTIGATIONS OF THE LAND BIOTIC O2:CO2 EXCHANGE RATIOS IN PHOTOSYNTHESIS AND RESPIRATION
Description:
Accurate estimations of the
land biotic O2/CO2 exchange ratios are required to allow
quantification of the land/ocean carbon sink partitioning from atmospheric
measurements of both O2 and CO2 concentrations.
This study shows atmospheric
O2 and CO2 mixing ratios as well as their diurnal cycles
over a three day period in May 2005 from flask samples collected at 3 different
heights (1, 4 and 12m) in an undisturbed
forest in central Germany. An average O2/CO2 ratio of
0.99 was estimated with very little variation between the three different
heights. In addition, the “night time” average value of atmospheric O2/CO2
ratio did not show any significant difference from the average “daytime” value.
Author's Names: E. Kozlova, A.C. Manning, A. Jordan and W. Brand
Filesize: 40.34 Kb
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CARBON BALANCE IN ABANDONED LANDS OF MOSCOW REGION IN RUSSIA
Description:
Carbon balance of cultivated
soil (loamy Phaeozems) under fallow was compared with that of soils abandoned
1, 5, 10, and 25 years converted naturally to permanent grassland (Moscow
region, Russia). Carbon inflow or net primary production (NPP) was calculated
as the sum of the above and below ground productivity of grassland ecosystems.
The total C outflow was equal to the annual CO2 fluxes from the
soils and was estimated as CO2 emission measured by the closed
chamber method. Carbon balance (CB) was defined as the difference between
respiration of heterotrophs and NPP. Botanical survey clearly showed that the
vegetation of abandoned agricultural lands changed to permanent grasslands
after 5 years of abandonment. Carbon inflow increased from 97 g C·m-2·yr-1 in the
arable soils to 1100 g C·m-2·yr-1 in the 10-yr grassland. Total
annual carbon losses from soils as CO2 amounted to 347-845 g
C·m-2·yr-1. Heterotrophic respiration varied from 272 g C·m-2·yr-1
in cultivated soil to 411 g C·m-2·yr-1 in 25-yr grassland. Our
estimations showed that 5, 10, and 25 yr grasslands act as carbon sink and
their C balance constituted -217 g C·m-2·yr-1, -778 g C·m-2·yr-1
and -473 g C·m-2·y-1, respectively. Arable soils under the fallow
act as CO2 source (CB = +175 g C·m-2·yr-1). Carbon
balance of the one-year grassland was close to zero. Hence, after 5 years
abandonment former arable lands converted to permanent grasslands become a
stable C sink.
Author's Names: I. N. Kurganova, A.M. Yermolaev, et al
Filesize: 46.55 Kb
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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
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