Elevated CO2, in the dark, is sometimes reported to inhibit leaf respiration, with respiration usually measured as CO2 efflux. Oxygen uptake may be a better gauge of respiration because non-respiratory processes can affect dark CO2 efflux in elevated CO2. Two methods of quantifying O2 uptake indicated that leaf respiration was unaffected by coincident CO2 level in the dark.

The southeastern landscape is composed of agricultural and forest systems that can store carbon (C) in standing biomass and soil. Research is needed to quantify the effects of elevated atmospheric carbon dioxide (CO2) on terrestrial C dynamics including CO2 release back to the atmosphere and soil sequestration. Longleaf pine savannahs are an ecologically and economically important, yet understu...

abstract radiation, water and co2 are three major resources requirement for crops growth and development and within a wide range, increasing each of them would increase the biosphere productivity. higher usage of fossil fuels is increasing the atmospheric co2 and according to known crop physiological functions, such conditions should increase the crops production. however there is a possibility...

The effects of elevated CO2 on nutrient cycling and selected belowground processes in the closed-canopy sweetgum plantation were assessed as part of a free-air CO2 enrichment (FACE) experiment at Oak Ridge, Tennessee. We hypothesized that nitrogen (N) constraints to growth response to elevated CO2 would be mitigated primarily by reduced tissue concentrations (resulting in increased biomass prod...

Extensive evidence shows that increasing carbon dioxide concentration ([CO2]) stimulates, and increasing temperature decreases, both net photosynthetic carbon assimilation (A) and biomass production for C3 plants. However the [CO2]-induced stimulation in A is projected to increase further with warmer temperature. While the influence of increasing temperature and [CO2], independent of each other...

The temperature dependence of C3 photosynthesis is known to vary according to the growth environment. Atmospheric CO2 concentration and temperature are predicted to increase with climate change. To test whether long-term growth in elevated CO2 and temperature modifies photosynthesis temperature response, wheat (Triticum aestivum L.) was grown in ambient CO2 (370 micromol mol(-1)) and elevated C...

We examined the influence of elevated CO2 concentration on denitrifier enzyme activity in wheat rhizoplanes by using controlled environments and solution culture techniques. Potential denitrification activity was from 3 to 24 times higher on roots that were grown under an elevated CO2 concentration of 1,000 micromoles of CO2 mol-1 than on roots grown under ambient levels of CO2. Nitrogen loss, ...

We exposed Populus tremuloides Michx. and Acer saccharum Marsh. to a factorial combination of ambient and elevated atmospheric CO2 concentrations ([CO2]) and high-nitrogen (N) and low-N soil treatments in open-top chambers for 3 years. Our objective was to compare photosynthetic acclimation to elevated [CO2] between species of contrasting shade tolerance, and to determine if soil N or shading m...

Atmospheric CO2 and O3 concentrations are increasing due to human activity and both trace gases have the potential to alter C cycling in forest ecosystems. Because soil microorganisms depend on plant litter as a source of energy for metabolism, changes in the amount or the biochemistry of plant litter produced under elevated CO2 and O3 could alter microbial community function and composition. P...

Atmospheric CO2 and tropospheric O3 are rising in many regions of the world. Little is known about how these two commonly co-occurring gases will affect reproductive fitness of important forest tree species. Here, we report on the long-term effects of CO2 and O3 for paper birch seedlings exposed for nearly their entire life history at the Aspen FACE (Free Air Carbon Dioxide Enrichment) site in ...