Relatively little is known about the implications of atmospheric CO2 enrichment for tree responses to biotic disturbances such as folivory. We examined the combined effects of elevated CO2 concentration ([CO2]) and defoliation on growth and physiology of sugar maple (Acer saccharum Marsh.) and trembling aspen (Populus tremuloides Michx.). Seedlings were planted in the ground in eight open-top c...

The extent to which greater net primary productivity (NPP) will be sustained as the atmospheric CO2 concentration increases will depend, in part, on the long-term supply of N for plant growth. Over a two-year period, we used common field and laboratory methods to quantify microbial N, gross N mineralization, microbial N immobilization, and specific microbial N immobilization in three free-air C...

The global carbon cycle is strongly perturbed by fossil fuel burning leading to atmospheric CO2 increase. Climatic warming followed by polar ice melting and global sea level rise are predicted due to the greenhouse effect of increasing CO2 in the atmosphere (Houghton et al. 1995). The ocean plays a major role in neutralizing the excess CO2 because the amount of inorganic carbon available for ex...

[1] Biological and geochemical CO2 proxies provide critical constraints on understanding the role of atmospheric CO2 in driving climate change during Earth history. As no single existing CO2 proxy is without its limitations, there is a clear need for new approaches to reconstructing past CO2 concentrations. Here we develop a new preQuaternary CO2 proxy based on the stable carbon isotope composi...

Experimental research investigating the responses of forest trees to rising concentrations of atmospheric CO2 has for the past two decades been justified on the basis of the prominent role of forests in the global carbon cycle. The C cycle regulates the airborne fraction of CO2 from fossil fuel combustion, and, therefore, the rate of increase of CO2 in the atmosphere and the associated effects ...

Greenhouse gas (GHG) emissions from oil and gas systems are an important component of the GHG emission inventory. To assess the carbon emissions from oilfield-produced water under atmospheric conditions correctly, in situ detection and simulation experiments were developed to study the natural release of GHG into the atmosphere in the Shengli Oilfield, the second largest oilfield in China. The ...

C4 photosynthesis is an adaptation derived from the more common C3 photosynthetic pathway that confers a higher productivity under warm temperature and low atmospheric CO2 concentration [1, 2]. C4 evolution has been seen as a consequence of past atmospheric CO2 decline, such as the abrupt CO2 fall 32-25 million years ago (Mya) [3-6]. This relationship has never been tested rigorously, mainly be...

The stable isotopic composition of dissolved inorganic carbon (υ13C-DIC) was investigated as a potential tracer of streamflow generation processes at the Sleepers River Research Watershed, Vermont, USA. Downstream sampling showed υ13C-DIC increased between 3–5‰ from the stream source to the outlet weir approximately 0Ð5 km downstream, concomitant with increasing pH and decreasing PCO2. An incre...

One strategy for plants to optimize stomatal function is to open and close their stomata quickly in response to environmental signals. It is generally assumed that small stomata can alter aperture faster than large stomata. We tested the hypothesis that species with small stomata close faster than species with larger stomata in response to darkness by comparing rate of stomatal closure across a...

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...