ACCURATE SIMULATION OF LOCAL DAILY CARBON FLUXES USING LARGE SCALE CLIMATE DATA SETS: EXAMPLE ...
Description: A Dynamic Global Vegetation Model
SEVER [Venevsky, Maksyutov, 2005] was
applied for the fourteen EUROFLUX sites [Valentini,
2003] with a large scale daily NCEP climate data as an input (0.5º x 0.5º
degree spatial resolution) for years 1997-2000 and net ecosystem exchange (NEE)
calculated and observed were compared. Requirements for accurate estimate of
local daily NEE flux from a large scale climate data set were found.
Author's Names: Sergey Venevsky, Shamil Maksyutov, Gen Inoue
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ADVECTIVE TRANSPORT OF CO2 IN PERMEABLE MEDIA INDUCED BY ATMOSPHERIC PRESSURE FLUCTUATIONS
Description:
Pressure fluctuations at the earth’s
surface are caused by a variety of atmospheric phenomena. Examples include low
frequency barometric pressure variations, high frequency atmospheric
turbulence, atmospheric gravity waves, and quasi-static pressure fields created
as wind blows over or around topographic features, like buildings, hills, wind
breaks, etc. These naturally occurring pressure fields cause air to move in and
out of soils, snowpacks, and other permeable media. Consequently, the uptake or
release of trace gases from soils and snowpacks is a combination of molecular
diffusion and advective flows caused by surface pressure fluctuations. Such
pressure forcing has been found to influence the exchange rate of many trace
gases from the underlying substrate to the atmosphere. Given the importance of
these trace gases to understanding biogeochemical cycling and global change, it
is crucial to quantify (as much as possible) any impact these advective flows
can have on gas transport within soils and snowpacks.
Author's Names: W. J. Massman
Filesize: 17.83 Kb
Added on: 02-Aug-2005 Downloads: 58
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AIRCRAFT TO INVENTORES: A MULTISCALED INVESTIGATION OF CARBON FLUXES IN A MONTANE LANDSCAPE
Description: As a result of landuse, 50%
or more of forests in the Northern Hemisphere mid-latitudes are in hilly to
mountainous terrain, accounting for half or more of the mid-latitude Gross
Primary Productivity. The mid-latitude sink observed in the atmosphere may
reflect carbon dynamics occurring in complex terrain. This is challenging: these regions are
inherently highly heterogeneous and currently reflect complex land use
histories, and atmospheric techniques for estimating spatially integrated
carbon fluxes don’t work well in sloping terrain. Consequently, the impacts of
climate, harvesting regimes, disturbances and fire/pest management on carbon
exchange are poorly constrained in mountains. While mountains are
heterogeneous, the orientation of slopes to incident radiation and
gravitational flows of air and water result in organization of the variability
that can be exploited. Analysis using model-data fusion techniques of long-term
eddy covariance data showed 1) mid-aged Rocky Mountain forests are sinks, 2)
most of the net uptake occurs in the spring when melting snow provides moisture
for photosynthesis but low soil temperatures inhibit respiration and 3)
interannual variability is mainly due to GEE and is largely driven by spring
temperature and precipitation, which both determine spring fluxes and set the
stage for mid-summer soil moisture conditions.
Author's Names: David Schimel, Britton Stephens, Russell Monson, et al
Filesize: 37.34 Kb
Added on: 05-Aug-2005 Downloads: 45
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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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ANNUAL CARBON DIOXIDE DRAWDOWN AND THE NORTHERN ANNULAR MODE
Description:
Year-to-year variations in summer drawdown of northern
hemisphere atmospheric carbon dioxide (CO2) are compared with
corresponding year-to-year variations in sea- level pressure (SLP), surface air
temperature and the productivity of land vegetation as inferred from the
satellite-derived normalized difference vegetation index (NDVI). Annual values
of CO2 drawdown for the years 1980-2000 are estimated from smoothed
time series derived directly from individual flask samples at the 9 northern
hemisphere monitoring stations with the most continuous records. The leading
principal component of the 9 standardized drawdown time series, in which all
stations exhibit positive loadings, is used to represent the hemispheric signal
in the CO2 drawdown. Linear regression analysis is used to infer the
spatial patterns of anomalies in sea level pressure, surface air temperature
and the NDVI observed during various seasons of years in which the drawdown is
anomalously strong.
Author's Names: J.L. Russell, E. Shevliakova, S. Malyshev, and J.M. Wallace
Filesize: 13.09 Kb
Added on: 04-Aug-2005 Downloads: 41
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APPARENT TRENDS IN PHOTOSYNTHETIC CAPACITY OF MONSOON ASIA FROM 1982 TO 2002
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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C4 VEGETATION COVERAGE AND PHOTOSYNTHESIS IN SOUTH AMERICA: SEASONAL AND INTERANNUAL VARIATIONS
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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CARBON ALLOCATION IN AN OLD-GROWTH FOREST IN THE GREAT LAKES REGION OF THE UNITED STATES
Description:
We
measured components of ecosystem respiration and biomass from wood, foliage and
roots in two stands in an old-growth hemlock-northern hardwood forest.
Respiration was measured by the chamber method and upscaled to the stand level.
Wood production was calculated from the increase in tree size. Foliage biomass
was measured from litterfall. Root production was measured from in-growth root
cores. Based on the measurements of respiration and biomass we calculated gross
primary production (GPP) and net ecosystem production (NEP).
The annual GPP was estimated as 1144 and 1089 g C m2 y-1
in the hardwood and hemlock stands, respectively. GPP was partitioned into 131,
115, 270, 168, 257, 203 g C m2 y-1 of wood, foliage, and
root respiration, and wood, foliage, and root production, respectively, in the
hardwood stand, and 206, 72, 155, 190, 139, 327 g C m2 y-1 of
wood, foliage, and root respiration, and wood, foliage, and root production,
respectively, in the hemlock stand. The percentage of GPP allocated to wood,
foliage and roots for growth and respiration was 20%, 23%, and 57%,
respectively, for the hardwood stand, and 31%, 14%, and 55%, respectively, for
the hemlock stand. The ratio of net primary production (NPP)/GPP was 30% in the
hardwood stand and 33% in the hemlock stand.
Author's Names: J. Tang, and P.V. Bolstad
Filesize: 30.54 Kb
Added on: 08-Aug-2005 Downloads: 61
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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
Added on: 01-Aug-2005 Downloads: 51
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CARBON BALANCE OF LARCH FOREST ECOSYSTEMS
Description:
We partitioned the components of
CO2 flux by the chamber
approaches for a 45-year-old larch forest in northern Japan.
In 2003, annual soil-CO2 efflux was averaged to 9.59 tC ha-1, heterotrophic respiration was about 5.47 tC ha-1 that accounted about 57% of the soil-CO2 efflux, net annual CO2 exchange of understory
vegetation was about -0.39 tC ha-1, annual aboveground
woody
tissue respiration
was bout 0.75 tC ha-1, and annual photosynthesis and respiration
of the canopy was about
-12.75 and 1.15 tC ha-1, respectively. Annual GPP, NPP, NEP and ecosystem
respiration for this forest was estimated
to be about 13.49, 7.16, 2.04 and 11.45 tC
ha-1, respectively. The contribution of canopy respiration,
aboveground
woody
respiration, root
respiration and heterotrophic respiration to GPP was about
8.1%, 5.6%, 30.6% and 40.5%, respectively.
Author's Names: N. Liang, Y. Fujinuma, and G. Inoue
Filesize: 41.90 Kb
Added on: 01-Aug-2005 Downloads: 64
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