TEMPORAL AND SPATIAL VARIABILITY OF CO2-CH4 SOURCE-SINK STRENGTH IN NORDIC ECOSYSTEMS
Description: In 2003 a Nordic Centre of Excellence on Ecosystem
Carbon Exchange and Its Interactions with the Climate System, NECC, was
initiated. The center comprises practically all eddy covariance flux sites (ca.
25) in the Nordic countries which, represents wetlands, coniferous and deciduous
forests, ‘Kyoto’
forests, lakes, agricultural sites and one urban site. The forest sites cover a
range of age classes and management practices, and long-term sites with more
than 8-10 years of continuous flux data. The center has also access to a flux
aircraft for regional assessments and involves high precision CO2
and CH4 measurements in high towers. A synthesis of the current
sink/source strength of CO2 and CH4 of the different
ecosystems is in preparation and will be presented. Analysis of long-term data
from a few sites and how it relates to annual parameters is also presented.
Author's Names: A. Lindroth
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TEMPERATURE CONTROLS ECOSYTEM CO2 EXCHANGE IN AN ALPINE MEADOW ON THE QINGHAI-TIBETAN PLATEAU
Description:
We examined CO2
flux over an alpine meadow on the northeastern Tibetan Plateau to elucidate how
temperature controls the carbon dynamics. The CO2 flux was measured in
a Kobresia meadow at an elevation of
3200m above sea level from 2002 to 2004 using the eddy covariance technique. The
alpine meadow was a weak sink of atmospheric CO2 with net ecosystem production
(NEP) of 193 g C m-2 yr-1
for 2004, which was about twice of that for the other two years. Both the low ecosystem
respiration (ER) and high gross primary
production (GPP) contributed the high
NEP in 2004. The annual GPP was 34g Cm-2 and 105 g C m-2
higher in 2004 than 2003 and 2002, respectively. The lowest GPP of 2002 was
clearly due to the low GPP in the autumn season when remarkably high air and
soil temperature were recorded. The low ER in 2004 was due to mainly the small ER
in the summer period when temperature was much lower than other years. In 2004,
the growing season was estimated to be about two weeks longer than the other
two years. The advance of growing season in 2004 corresponded well to the
temperature elevation in the spring season. Further analysis showed that the
day/night difference in soil temperatures was positively correlated to the
daily net ecosystem CO2 exchange. The study suggests that
temperature environment plays the major role in the annual variation of NEP in
the alpine meadow ecosystem.
Author's Names: Y. Tang, T. Kato, S. Gu, M. Hirota, M. Du and X. Zhao
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TALL TOWER CARBON BUDGET MONITORING AND RESEARCH PROGRAMS IN HUNGARY
Description:
The
mixing ratio and the surface-atmosphere exchange of carbon dioxide have been
monitored at different elevations on a tall tower in West
Hungary (Hegyhátsál, 46o57'N, 16o39'E, 248 m
asl) since 1994 and 1997, respectively. The vertical mixing ratio profile
measurements along the 115 m tall tower has been completed with occasional
aircraft measurements up to 3000 m above the ground. The poster presents the
Hungarian tall tower site and the temporal variation of carbon dioxide observed
here. We discuss the region of influence determining the mixing ratio
variability, the so-called concentration footprint, as well as that of the flux
measurements. Methodological problems caused by the elevated monitoring levels,
and their solutions, are also given. The environmental factors governing the
net ecosystem exchange (NEE) of the vegetation are analyzed by means of a
process oriented ecosystem simulation model. It might be used to estimate the
future behavior of the region as the climate is changing. On the basis of the
measurements at Hegyhátsál a boundary layer model has been developed which can
give rough surface-atmosphere carbon dioxide flux estimate for sites where only
surface mixing ratio monitoring is available.
Author's Names: L. Haszpra, Z. Barcza, D. Hidy, T. Szabó, and K. Tarczay
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Added on: 29-Jul-2005 Downloads: 23
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SYNTHESIS OF TOP-DOWN AND BOTTOM-UP SCALING OF REGIONAL TERRESTRIAL CARBON DIOXIDE ...
Description: Quantifying the
regional scale (10-1000 km) exchange of carbon dioxide between terrestrial
ecosystems and the atmosphere is vital for understanding the spatial and
temporal variation in global CO2 flux. Multiple investigations of
top-down and bottom-up regional flux scaling are currently underway in the
northern Great Lakes region, USA. Landscape and regional scale CO2
fluxes from multiple line of evidence, including eddy covariance multi-tower
aggregation, tall-tower flux footprint decomposition, ecosystem modeling, CO2
mixing ratio boundary layer budgets and regional inversions reveal variations
in CO2 flux arising from variations in vegetation type, canopy
structure and interannual climate variability. With careful calibration, encouraging
consistency is seen from several independent regional flux estimates. Without
parameter optimization and high resolution maps of land cover, global scale
remote-sensing and ecosystem-model CO2 flux estimates fail to
accurately capture the local regional CO2 flux. These results
represent a first attempt to cross-compare multiple top-down and bottom-up
regional flux estimates.
Author's Names: A.R. Desai, W. Wang, D.M. Ricciuto, B.D. Cook, et al
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Added on: 28-Jul-2005 Downloads: 39
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SPATIO-TEMPORAL EVALUATION OF SOIL CARBON STORAGE OF CROPLANDS IN JAPAN
Description:
We evaluated the current
status and the future projection of soil organic carbon (SOC) storage in
Japanese croplands (paddy and upland), using a soil carbon turnover model. The
model based on the RothC involves the modification after verification of
turnover processes of SOC for the main soil type in Japan, Andosols. The objectives of
this study are to i) evaluate the spatial distribution of SOC storage, ii)
estimate the annual input organic matter for reaching the equilibrium, and iii)
simulate time changes of SOC storage with changing agricultural practices as
well as climate conditions.
Author's Names: M. Yokozawa, Y. Shirato, S. Yonemura and T. Sakamoto
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Added on: 09-Aug-2005 Downloads: 24
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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
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Added on: 26-Jul-2005 Downloads: 34
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SPATIAL PATTERNS OF CARBON RESIDENCE TIMES AND SEQUESTRATION CAPACITY IN ECOSYSTEM OF THE ...
Description:
To properly model carbon (C) sequestration capacity and its spatial
pattern in the conterminous USA,
the model parameters of C turnover times should be identified. In this study,
we inversed the C turnover times based on a process-based model that combining
Carnegie-Ames-Stanford Approach (CASA
model) and vegetation and soil carbon transfer (VAST)
model. The genetic algorithm was used in this study to search for optimal parameters
of C turnover times. After inversing the spatial pattern of C turnover times,
we modeled the carbon sequestration capacity by using a forward model under
current NPP increase trend that derived from satellite data.
Author's Names: T. Zhou, and Y. Luo
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SPATIAL AND TEMPORAL PATTERNS OF CO2, CH4 AND N2O FLUXES IN THE TERRESTRIAL ECOSYSTEMS OF ...
Description: The
magnitude and spatial pattern of the emissions of CO2, CH4
and N2O from China’s
terrestrial ecosystems are poorly understood. In this study, we have used a
coupled biogeochemistry model in conjunction with remote-sensing and field data
to quantify spatial and temporal patterns of CO2, CH4 and
N2O fluxes in the terrestrial ecosystems of China since
1980. We have documented the patterns of land-use change across China from 1980
to present and quantified the consequences of land transformations on
productivity in natural and managed ecosystems. We also examine how the fluxes
of CO2, CH4 and N2O have changed as a result
of multiple stresses and interactions among those stresses including land-use
change, climate variability, atmospheric composition (carbon dioxide and
tropospheric ozone), precipitation chemistry (nitrogen composition), and fire
frequency through using factorial simulation experiments with the coupled
biogeochemistry model. The estimates of CO2, CH4 and N2O
emissions from the terrestrial ecosystems of China are evaluated through
comparisons with the results of field studies within China.
Author's Names: H. Tian, M. Liu, W.Ren, X. Xu, G. Chen, and H. Chen
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SOIL CO2 FLUX FROM A TROPICAL DRYLAND RICE-BARLEY-FALLOW AGROECOSYSTEM: IMPACT OF APPLICATION ...
Description: Information on loss of carbon in form of CO2
from the soil in response to soil amendments is wanting in tropical dryland
agroecosystems. This two year study of soil CO2 in tropical dryland
agroecosystem supporting rice-barley-fallow annual sequence involved addition
of equivalent amount of N through chemical fertilizer and three organic inputs
(high quality resource, low quality resource, and high and low quality resource
combined) besides control. A marked seasonal variation was noticed in CO2 flux
in all treatments, with higher levels obtained during rice crop (warm-wet
period) and considerably decreased flux during barley crop (cool dry, period).
CO2 flux differed in various treatments. In terms of annual mean,
low quality input showed 92% greater CO2 flux relative to control
(127 mg CO2 m-2 hr-1) whereas combined input
showed 75% increase. However, the CO2 flux expressed on the basis of
per unit exogenous carbon added was ca.100 times higher in case of fertilizer
relative to low quality input application (ca. 11 mg CO2 g-1
C hr-1) (cf. High quality input, 3 times, and combined input 1.5
times greater). These results show that CO2 flux is more related to
C input than the input of N.
Author's Names: N. Ghoshal, S. Singh, and K.P. Singh
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SOIL CO2 CONCENTRATIONS AND FLUXES IN A PLOW-MANAGED AGRICULTURAL FIELD, A GRASS FIELD AND A FOREST
Description:
In this paper we briefly introduce our results
of soil CO2 concentrations in an arable field in the campus of
NIAES, a grass field and a pine forest in central mountaneous area in Japan. The soil CO2 concentrations
seasonally variated with soil temperature changes at all the three sites. Temporal variations in CO2
concentrations in the arable and the grass field were more linked to changes in
soil moisture than those in the forest. Soil CO2 concentrations were
generally largest in the grass field. CO2 concentrations at the
grass field and pine forest under snow cover showed positive relationship with
snow depth.
Author's Names: S. Yonemura, M. Yokozawa, Y. Shirato, S. Sekikawa, et al
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