IMPACT OF ELEVATED CO2 ON THE FOOD PRODUCTION OF NEPAL
Description: The
three cereal crops rice, maize and wheat cover over 75% of the total food
production of Nepal.
All the three crops rice, maize and wheat showed increased yield with doubling
the CO2 level but also followed a declined tendency at the elevated
temperature. Among the three crops, maize was the most affected by the rise in
temperature although increased CO2 level could increase the crop
yield. The Terai plains and the hills of Nepal were more affected. The
mountains, on the other hand, showed a favorable tendency.
Author's Names: Kishore Sherchand
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Added on: 04-Aug-2005 Downloads: 32
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IMPACT OF ELEVATED CO2 AND TEMPERATURE ON SOIL CARBON SEQUESTRATION POTENTIAL OF TWO CONTRASTING...
Description: Carbon sequestration in soils might offset part
of the increase of CO2 in the atmosphere. Two contrasting
subtropical grassland species, bahiagrass (BG), Paspalum notatum Flügge, and rhizoma perennial peanut (PP), Arachis glabrata Benth., a legume, were
grown at Gainesville, Florida, USA, in field soil plots in four temperature
zones (baseline-ambient, +1.5, +3.0, and +4.5 °C) in four temperature-gradient
greenhouses, two each at 360 and 700 ppm CO2. The soil had been in
continuous cultivation for more than 20 years before plant establishment. Samples
from the top 20 cm of each plot were collected before plant establishment and six
years later, after the study ended. Soil organic carbon (SOC) increases across
the six years were greater for BG than PP, 1.396 and 0.746 g/kg, respectively. Belowground
biomass was also greater for BG than PP. Mean SOC gains in BG plots at 700 and
360 ppm CO2 were 1.450 and 1.343 g/kg, respectively (no CO2
effect). Mean SOC increases in PP plots at 700 and 360 ppm CO2 were
0.949 g/kg and 0.544 g/kg, respectively (significant CO2 effect).
Overall, SOC increased only for the first temperature increment, and thereafter
declined. Soil organic nitrogen (SON) accumulation patterns were similar to SOC
increases. Mean annual SOC accumulation was 475 kg/ha per year, comparable with
other studies. We conclude that carbon can be accumulated in soils converted to
grassland species in humid, subtropical environments. The SOC accumulation will
be greatest for species that have greater belowground biomass accumulation.
Author's Names: L.H. Allen, Jr, S.L. Albrecht, K.J. Boote, J.M.G. Thomas, and K.W. Skirvin
Filesize: 29.38 Kb
Added on: 25-Jul-2005 Downloads: 36
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FOREST MICROMETEOROLOGICAL RESPONSES TO INCREASED CO2 AND O3 CONCENTRATIONS
Description: The
Forest-Atmosphere Carbon Transfer and Storage (FACTS-II) Project in northern
Wisconsin is examining the interacting effects of elevated carbon dioxide (CO2)
and ozone (O3) concentrations on the productivity, sustainability,
and competitive interactions in a regenerating northern hardwood
ecosystem. A key component of this
project involves an examination of the micrometeorological feedback mechanisms
that can alter atmospheric environments within and above vegetation layers
exposed to elevated CO2 and O3 concentrations. This paper provides a brief summary of some
of the observed forest micrometeorological responses to elevated CO2
and O3 concentrations at the FACTS-II study site over the 1999-2004
period.
Author's Names: W.E. Heilman, and R.M. Teclaw
Filesize: 58.80 Kb
Added on: 29-Jul-2005 Downloads: 41
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GROWTH AND PHOTOSYNTHETIC RESPONSE OF DECIDUOUS TREE SAPLINGS IN A FREE AIR CO2 ENRICHMENT SYSTEM
Description:
We
examined the photosynthetic and growth traits of two woody species (birch) that
are dominant in northern Japan
under elevated CO2 concentration ([CO2]), using a free
air CO2 enrichment (FACE) system. Our results suggest that it is necessary to consider not only leaf-level
photosynthesis but also the entire plant physiology when using photosynthesis
to evaluate the growth response of two birch saplings under elevated [CO2].
Author's Names: N. Eguchi, K. Karatsu, T. Ueda, R. Funada, et al
Filesize: 123.78 Kb
Added on: 28-Jul-2005 Downloads: 42
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FEEDBACKS BETWEEN CLIMATE AND THE ATMOSPHERE IN FOREST GROWTH: CLIMATIC VARIATION MEDIATES ...
Description: CO2 and O3 are accumulating in
the atmosphere and are potent modifiers of forest growth, causing changes that
could alter composition and functioning of forest ecosystems. We have examined the effects of elevated CO2
( +CO2; 560ppm), elevated O3 (+O3; 1.5X
ambient), and their combination (+CO2+O3),
on the growth and productivity of model aspen (Populus tremuloides Michx.) and aspen-birch (Betula papyrifera Marsh.) forest ecosystems growing in an open
free-air exposure (FACE) system in northern Wisconsin USA. After eight years of fumigation, +CO2
increased aspen tree and stand volume growth by 39 + 9% and 38 +
10%, respectively, whereas +O3 decreased them by 27 + 6% and
34 + 4%, respectively. +CO2+O3 resulted in a net
canceling of the effects of the single gases on aspen growth. Forest
growth responses to +CO2 and +O3 interacted strongly with
present-day interannual variability in climatic conditions. The amount and
timing of photosynthetically active radiation and temperature coinciding with
growth phenology explained 33-61% of the annual variation in growth responses
of aspen trees, and explained 20-63% of annual variation in growth responses of
aspen tree stands.
Author's Names: M.E. Kubiske, V.S. Quinn, W.E. Heilman, et al
Filesize: 73.21 Kb
Added on: 03-Aug-2005 Downloads: 43
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BAYSIAN INVERSION OF A TERRESTRIAL ECOSYSTEM MODEL AND UNCERTAINTY ANALYSIS
Description:
We applied the Bayesian
probability inversion and a Markov Chain Monte Carlo (MCMC)
technique to a terrestrial ecosystem model and analyzed uncertainties of
estimated carbon transfer coefficients and simulated carbon pool sizes. The
study used six data sets of soil respiration, woody biomass, foliage biomass,
litterfall, carbon content in the litter layers, carbon content in mineral soil
measured under both ambient CO2 (350 ppm) and elevated CO2
(550 ppm) plots from 1996 to 2000 at the Duke Forest Free-Air CO2
Experiment (FACE) site.
Author's Names: Tao Xu, Yiqi Luo
Filesize: 244.22 Kb
Added on: 09-Aug-2005 Downloads: 45
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CLIMATE CHANGE FEEDBACKS ON OCEANIC pH AND Ω
Description: Anthropogenic CO2 uptake by the ocean will decrease both the pH
and the aragonite saturation state (Ωarag) of seawater. However, the factors controlling future changes
in pH and Ωarag are independent and will respond differently to oceanic
climate change feedbacks such as ocean warming, circulation and biological
changes. We examine the sensitivity of
these CO2-related parameters to climate change feedbacks within a
coupled atmosphere-ocean model. Although surface pH is projected to decrease
relatively uniformly by ~0.25 by the year 2100, we find pH to be insensitive to
climate change feedbacks, whereas Ωarag is buffered by ~15%. The independent
climate change response between pH and Ωarag is attributed solely to
the opposing effects associated with ocean warming, which increases Ωarag
but lowers pH. Our result implies that
future climate change projections for surface ocean pH can be adequately
simulated using ocean-only models, however for Ωarag more complex
coupled atmosphere-ocean models are required.
Author's Names: B. I. McNeil and R. J. Matear
Filesize: 181.80 Kb
Added on: 02-Aug-2005 Downloads: 48
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EFFECT OF ECTOMYCORRHIZAL INFECTION ON THE GROWTH AND PHOTOSYNTHETIC CHARACTERISTICS OF THREE ...
Description: After 18 weeks, elevated CO2 (720 μmol·mol-1) increased significantly the
ectomycorrhizal development. The phosphate concentration (P) in needles of Pinus densiflora and Larix kaempferi inoculated with Pt or EC was significantly higher than that without
inoculation at both CO2 concentrations. Pt or EC inoculation had led to significantly increase the
physiological activities, such as the PAR
saturated net photosynthetic rates (Psat),
maximum net photosynthetic rate at saturated CO2 concentration (Pmax), carboxylation efficiency (CE), RuBP
regeneration rate of A/Ci curve and
water use efficiency (WUE) of P. koraiensis,
P. densiflora and L. kaempferi seedlings grown at both CO2
concentrations (360 and 720 μmol·mol-1) relative to non-inoculated
seedlings. Moreover, dry mass and
stem diameter of inoculated P. koraiensis,
P. densiflora and L. kaempferi seedlings significantly
higher than those non-inoculated seedlings.
Author's Names: D.S. Choi, Y. Maruyama, H.O Jin, K. Sasa and T. Koike
Filesize: 94.25 Kb
Added on: 28-Jul-2005 Downloads: 53
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CALCITE AND ARAGONITE UNDERSATURATION UNDER RISING ATMOSPHERIC CARBON DIOXIDE CONCENTRATIONS ...
Description:
Increasing atmospheric CO2
concentrations lowers oceanic pH and carbonate ion concentrations, thereby
decreasing the level of saturation of calcium carbonate [Feely et
al., 2004]. This acidification will eventually lead to
undersaturation and dissolution of calcium carbonate in parts of the surface
ocean. Besides affecting the global carbon cycle, these changes threaten marine
organisms that form their exoskeletons out of CaCO3, which are
essential components of the marine food web [Orr et al.,
2005]. We investigate magnitude and pattern of ocean acidification due to
increasing atmospheric CO2 concentrations and global warming, both
for the recent past and the near future, using the reduced complexity, Bern 2.5-D
physical-biogeochemical climate model and a series of CO2 emission
scenarios and CO2 stabilization profiles provided by the
Intergovernmental Panel on Climate Change (IPCC). The focus of the study is on
the impact of global warming and induced ocean circulation changes on the
projected oceanic pH and carbonate ion reductions.
Author's Names: G.-K. Plattner, F. Joos, T. Stocker, and J. C. Orr
Filesize: 24.71 Kb
Added on: 03-Aug-2005 Downloads: 53
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A PAEO PERSPECTIVE ON THE OCEAN'S ROLE IN THE CARBON CYCLE
Description: Recently developed proxies for the seawater carbonate ion concentration
were used to reconstruct the vertical gradient in the carbonate ion
concentration for times in the past corresponding to the
glacial-interglacial cycles. The reconstructed changes leave little
doubt that the ocean drove the large natural variations in atmospheric
carbon dioxide that accompanied the glacial cycles, most likely through
the combined influence of changes in the biological pump and deep ocean
circulation. Below 1500 m the carbonate ion concentration changes
little, evidence of the ocean’s ability to buffer changes in carbon
chemistry over thousands of years.
Author's Names: David M. Anderson
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Added on: 26-Aug-2005 Downloads: 59
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