EFFECT OF ENRICHED CO2 ON RICE UNDER OPEN TOP CHAMBER CONDITION AT KHUMALTAR
Description:
The effect of CO2
enrichment in raising the temperature was realized in the Open Top Chamber
(OTC) experiment. The elevated CO2 with this level of temperature
raised grain yield and yield components of rice but varied greatly by year. The
CO2 enriched plot had lesser N, P, and K in grain, straw, and root
but higher organic carbon (OC) in the root compared to the Ambient and the
Field. The study indicated that this rise of temperature due to the elevated CO2
could not adversely affect the yield.
Author's Names: K. Sherchand, G. Malla, A. Sharma and S. Shrestha
Filesize: 53.20 Kb
Added on: 04-Aug-2005 Downloads: 64
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EFFECT OF ELEVATED CO2 ON GROWTH, BIOMASS PRODUCTION AND PHOTOSYNTHESIS OF PANICUM MAXIMUM AND ...
Description:
In P. maximum the
cumulative dry biomass production in two cuttings showed an increase of 59.24%
and 43.17% in open top chambers (OTC) with elevated CO2 (600±50
ppm) (C600) and without elevated CO2 (COTC)
respectively over the open field grown corps (Ca). In S. hamata the dry matter increased by
39.79% under C600 and 31.02% in COTC over Ca. The canopy
photosynthesis (PN x LAI) increased significantly in both the crop
species with elevated CO2. The increased rate of canopy
photosynthesis indicated that there was higher assimilation of CO2,
which has intern maximum biomass production. The increase in fresh and dry
matter accumulation in C600 indicating that these crop species
should be promoted for higher biomass production and carbon sequestration in
the semi arid tropical environmental conditions.
Author's Names: R. K. Bhatt, M.J. Baig, Jyoti Dubey and H. S. Tiwari
Filesize: 90.35 Kb
Added on: 05-Aug-2005 Downloads: 64
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EFFECT OF ELEVATED ATMOSPHERE CO2 CONCENTRATION ON COTTONWOOD TREE GROWTH AND SOIL RESPIRATORY ...
Description: The effect of three atmospheric CO2 concentrations (ambient –
400 ppm, doubled – 800 ppm and tripled – 1200 ppm) has been studied (1) on the
productivity of cottonwood tree (Populus
deltoides Barr.), (2) on the activity of soil microbial biomass in rooting
zone. It has been shown, that the total biomass of cottonwood trees increase under
elevated CO2 (2.61, 5.59 and 4 kg/tree for 400, 800 and 1200 ppm
respectively). The highest production had the stem and coarse roots at 800 ppm (in
3 and 2 times higher as compared to ambient CO2). Under 1200 ppm CO2
we observed increased the roots biomass, but the biomass of leaves and branches
was insignificant or didn’t changed at all. The shoot/root ratio changed as
following: 400 ppm – 1.8, 800 ppm – 2.3, 1200 ppm – 1.4. The rate of С-СО2
flux from soil samples being incubated for 70 days increased in the row 1200>800>400
ppm CO2, the average values of CO2 emission were 2.76, 2.33,
2.02 mg 100g-1·day-1, respectively. The largest amount of
C microbial biomass (Cmb) was in the variant with triple CO2
concentration (75.1 mg 100g-1), and the lowest – under ambient
concentration (53.7 mg 100g-1).
Author's Names: V.N.Kudeyarov, K.Biel, S.A.Blagodatsky, V.M.Semenov, et al
Filesize: 108.71 Kb
Added on: 01-Aug-2005 Downloads: 66
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CORAL REEF CALCIFICATION AND CLIMATE CHANGE: THE EFFECT OF OCEAN WARMING
Description:
Coral
reefs are constructed of calcium carbonate (CaCO3). Deposition of
CaCO3 (calcification) by corals and other reef organisms is
controlled by the saturation state of CaCO3 in seawater (Ω) and sea
surface temperature (SST). Previous studies have neglected the effects of ocean
warming in predicting future coral reef calcification rates. In this study we take into account both these
effects by combining empirical relationships between coral calcification rate
and Ω and SST with output from a climate model to predict changes in coral reef
calcification rates. Our analysis suggests
that annual average coral reef calcification rate will increase with future
ocean warming and eventually exceed pre-industrial rates by about 35% by 2100.
There is evidence however to suggest that different corals display different
sensitivities to changes in Ωarag and SST [Reynaud et al., 2003]. Considering that both these environmental
parameters are likely to change considerably in the future, additional
experiments on a variety of differing coral species will be crucial to obtain a
better understanding of future coral reef stability.
Author's Names: B. I. McNeil, R. J. Matear and D. J. Barnes
Filesize: 154.39 Kb
Added on: 02-Aug-2005 Downloads: 95
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THE ROLE OF WATER RELATIONS IN DRIVING GRASSLAND ECOSYSTEM RESPONSES TO RISING ATMOSPHERIC CO2
Description:
While
rising atmospheric carbon dioxide (CO2) is known to be an important
contributor to radiative forcing of Earth’s climate, more direct effects of
this gas on photosynthesis and plant water relations have been underway for
more than a century, and likely have already contributed to important ecosystem
changes. Experiments conducted in native and semi-natural grasslands in which ambient
CO2 concentrations have been artificially increased have shown that
increasing CO2 often increases photosynthesis, results in higher
soil and plant water content, and can enhance plant water use efficiency, the
ratio of plant biomass produced per unit water transpired back to the
atmosphere. While these responses may appear beneficial, there are long-term
responses of ecosystems to CO2 such as alterations in the cycling
and availability of critical plant nutrients like nitrogen (N) which are likely
to change over time and may significantly alter CO2-enhanced
production and forage quality. Herein we discuss these phenomena and speculate
on the implications and the importance for world grasslands.
Author's Names: J.A. Morgan, E. Pendall, A.R. Mosier,et al
Filesize: 31.72 Kb
Added on: 02-Aug-2005 Downloads: 122
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UNRAVELING THE DECLINE IN HIGH-LATITUDE SURFACE OCEAN CARBONATE
Description: For perhaps 25 million years, surface waters throughout the ocean have
remained saturated with respect to calcium carbonate (CaCO3). Yet increasing atmospheric CO2
reduces ocean pH and carbonate ion concentration [CO32-] and thus the level of saturation. Despite this acidification, it has been
estimated that all surface waters will remain saturated for centuries. However,
marine calcifiers are still expected to suffer reductions in the rate at which
they form their exoskeletons out of CaCO3. Here we show with ocean
data and models that the anthropogenic acidification will actually cause some
surface waters to become undersaturated within decades, thus exacerbating the
problem for marine calcifiers [Orr et al.,
2005]. For instance, by 2050 when atmospheric CO2 reaches 550 ppmv
under the IS92a business-as-usual scenario, Southern Ocean surface waters begin
to become undersaturated with respect to aragonite, a metastable form of CaCO3.
By 2100 as atmospheric CO2 reaches 788 ppmv under the same scenario,
undersaturation extends throughout the entire Southern Ocean (all ocean south
of 60°S) and into the surbarctic Pacific.
Author's Names: J. C. Orr, V. J. Fabry, O. Aumont, L. Bopp, et al
Filesize: 92.06 Kb
Added on: 03-Aug-2005 Downloads: 142
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NITROGEN REGULATION OF CARBON SEQUESTRATION IN TERRESTRIAL ECOSYSTEMS IN RESPONSE TO RISING ...
Description:
A highly controversial issue in global change
research is the regulation of terrestrial carbon (C) sequestration by soil
nitrogen (N) availability. The Third Assessment IPCC Report predicts rising atmospheric CO2
alone could stimulate terrestrial carbon (C) sequestration by 350 – 980 Pg (=1015
g) C in the 21st Century. Sequestering 350 – 980 Gt C in terrestrial
ecosystems requires 7.7 – 37.5 Pg (N) based on a stoichiochemical relationship
that approximately 0.005 g N is required for 1 g C stored in long-lived plant
biomass (i.e., wood) and 0.067 g N for 1 g C sequestered in soil organic matter
(SOM). Thus, to realistically predict
future C sequestration in terrestrial ecosystems, we have to understand how
closely C and N processes are coupled in response to rising Ca.
Author's Names: Yiqi Luo
Filesize: 24.39 Kb
Added on: 01-Aug-2005 Downloads: 158
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THE POTENTIAL OF UPPER OCEAN ALKALINITY CONTROLS FOR ATMOSPHERIC CARBON DIOXIDE CHANGES
Description:
Extreme
global model scenarios of complete preservation and degradation of biogenic
particulate CaCO3 (calcium carbonate) in open ocean waters which are
supersaturated with respect to CaCO3 were carried out. According to
these experiments, the theoretical potential of upper ocean alkalinity controls
for changing the atmospheric pCO2 (CO2 partial pressure)
amounts to several hundred μatm on time scales of several 104 years.
Up to a timescale of 103 years, however, the respective influence is
minor as compared to an expected anthropogenic increase of the atmospheric pCO2
in the order of 500-1000
μatm.
Author's Names: Christoph Heinze
Filesize: 80.15 Kb
Added on: 29-Jul-2005 Downloads: 162
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SUBSTRATE INDUCED GROWTH RESPONSE OF SOIL AND RHIZOSPHERE MICROBIAL COMMUNITIES UNDER ELEVATED CO2
Description: The
maximal specific growth rate of microorganisms from rhizospheres of Populus deltoides grown under normal CO2 concentration
in the atmosphere (400 ppm) was lower compared to the assessments made for
plots under elevated CO2 (800 and 1200 ppm). A similar conclusion
was made for microbial communities from soil under winter wheat and sugar beets
grown under 370 and 550 ppm CO2 in the atmosphere. Three to four
years fumigation of field plots with elevated CO2 has been shown to
result in the formation of rhizosphere microbial communities characterized by
faster specific growth rates as compared to microbial community under control
plants.
Author's Names: S.A. Blagodatsky, E.V. Blagodatskaya, T.-H. Anderson, et al
Filesize: 147.23 Kb
Added on: 26-Jul-2005 Downloads: 196
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