Burned landscapes present several challenges to quantifying landscape carbon balance. Fire scars are composed of a mosaic of patches that differ in burn severity, which may influence postfire carbon budgets through damage to vegetation and carbon stocks. We deployed three eddy covariance towers along a burn severity gradient (i.e., severely burned, moderately burned, and unburned tundra) to mon...

31 32 A better understanding of the mechanisms controlling the magnitude and sign of carbon components in 33 tropical forest ecosystems is important for reliable estimation of this important regional component of the 34 global carbon cycle. We used the JULES vegetation model to simulate all components of the carbon balance 35 at six sites along an Andes-Amazon transect across Peru and Brazil an...

For an economically competitive biological process, achieving high carbon yield of a target chemical is crucial. In biochemical production, pyruvate and acetyl-CoA are primary building blocks. When sugar is used as the sole biosynthetic substrate, acetyl-CoA is commonly generated by pyruvate decarboxylation. However, pyruvate decarboxylation during acetyl-CoA formation limits the theoretical ma...

This paper reviews the effects of past forest management on carbon stocks in the United States, and the challenges for managing forest carbon resources in the 21st century. Forests in the United States were in approximate carbon balance with the atmosphere from 1600-1800. Utilization and land clearing caused a large pulse of forest carbon emissions during the 19th century, followed by regrowth ...

Carbon balance is characterized by the net ecosystem productivity (NEP), the difference between net primary productivity (NPP) and the heterotrophic respiration (Rh), namely the decomposition of dead organic matter by soil microbes. At the global scale, NEP is of great interest because it indicates the capacity of terrestrial ecosystems absorbing/releasing CO2 from/to the atmosphere. In this pa...

The carbon/nutrient balance hypothesis suggests that leaf carbon to nitrogen ratios influence the synthesis of secondary compounds such as condensed tannins. We studied the effects of rising atmospheric carbon dioxide on carbon to nitrogen ratios and tannin production. Six genotypes of Populus tremuloides were grown under elevated and ambient CO(2) partial pressure and high- and low-fertility s...

A better understanding of the mechanisms controlling the magnitude and sign of carbon components in tropical forest ecosystems is important for reliable estimation of this important regional component of the global carbon cycle. We used the JULES vegetation model to simulate all components of the carbon balance at six sites along an Andes-Amazon transect across Peru and Brazil and compared the ...

On average, about 45 per cent of global annual anthropogenic carbon dioxide (CO(2)) emissions remain in the atmosphere, while the remainder are taken up by carbon reservoirs on land and in the oceans-the CO(2) 'sinks'. As sink size and dynamics are highly variable in space and time, cross-verification of reported anthropogenic CO(2) emissions with atmospheric CO(2) measurements is challenging. ...

Research Professor, Systems Ecology Research Group, San Diego State University, San Diego, Calif., 92182. Abstract: Photosynthesis and respiration rates were determined for chaparral shrubs as a function of temperature and/or light intensity. In mature stands at Echo Valley, Calif., net seasonal carbon assimilation by leaves ranges -2 from a dry weight equivalent of 673 g m -1 in -2 pure stands...

Terrestrial ecosystems are estimated to contain 3000 Pg of organic carbon (C) of which more than two thirds are stored in soils (Jobbágy and Jackson 2000). Total soil organic carbon (SOC) consists of different C pools with intrinsic turnover rates ranging from less than a year to thousands of years (Amundson 2001). The processes that drive the cycling of soil C are C inputs from net primary pro...