Carbon sequestration studied in western U.S. mountains

Abstract

The U.S. carbon budget has been the focus of recent scientific debate [Fan et al., 1998; Pacala et al., 2001; Gurney et al., 2002] Even conservative estimates suggest that U.S. ecosystems take up a significant amount of carbon, largely as a result of historical land use practices [Houghton et al., 1999; Schimel et al.,2000; Pacala et al., 2001]. In the western United States, a key cause of carbon sequestration is fire suppression. Fire suppression, of course, also sets the stage for the catastrophic losses that are occurring during fire season 2002. Increases in fire due to the effects of fire suppression, increased prescribed burning and thinning, and climate change could significantly affect the national carbon budget. At the continental scale, a comprehensive research approach—the North American Carbon Program (NACP)—is planned to quantify carbon exchange and improve our understanding of the contributing processes [Wofsy and Harriss, 2002].

Contribution of advection to the carbon budget measured by eddy covariance at a steep mountain slope forest in Switzerland

“…Furthermore, forest ecosystems act as an important sink within the global carbon cycle (e.g., Janssens et al, 2003;Luyssaert et al, 2008). Thus, regions with complex topography are among the most important regions for determining local and global carbon and water budgets (Schimel et al, 2002). Therefore it is necessary to extend the application of the EC technique to mountain ecosystems, such as mountain forests to understand ongoing processes and be able to include these ecosystems into global calculations and models.…”

The Contribution of Advective Fluxes to Net Ecosystem Exchange in a High‐elevation, Subalpine Forest

“…As eddy flux networks become increasingly more utilized to provide the observational constraint on regional and global carbon models, it will be important to quantify and reduce these uncertainties. This will be especially important in regions, such as the western continental United States, where over half of the annual carbon sequestration occurs in ecosystems with hilly or mountainous terrain (Schimel et al 2002).…”

A Multiscale and Multidisciplinary Investigation Of Ecosystem–Atmosphere CO2 Exchange Over the Rocky Mountains of Colorado

“…y conducting model-data assimilation analysis of the long-term eddy covariance dataset from the Niwot Ridge AmeriFlux site operated by the University of Colorado, Schimel et al (2002), Sacks et al (2006Sacks et al ( , 2007, Monson et al (2005Monson et al ( , 2006a, and Moore et al (2008) showed that 1) an aggrading Rocky Mountain subalpine forest is a net annual CO 2 sink, 2) most of the annual CO 2 uptake occurs in spring when melting snow provides moisture for photosynthesis and low soil temperature inhibits respiration, and 3) the interannual variability of forest CO 2 uptake is largely driven by spring conditions. Studies at the same forest site showed, however, that accurate estimates of ecosystem CO 2 exchange are difficult to obtain because the terrain forces us to consider terms that are otherwise ignored in systems with seemingly simpler terrain (Yi et al 2005;Sun et al 2007;Yi et al 2008).…”

“…Studies at the same forest site showed, however, that accurate estimates of ecosystem CO 2 exchange are difficult to obtain because the terrain forces us to consider terms that are otherwise ignored in systems with seemingly simpler terrain (Yi et al 2005;Sun et al 2007;Yi et al 2008). Using a biogeochemistry model driven by historical climate data, Schimel et al (2002) found that ~50% of the western U.S. carbon sink occurs over hilly or mountainous topography with elevations above 750 m. Because a significant fraction of forests worldwide occur in hilly and mountainous terrain, and because this terrain imposes unique challenges to the quantification of local and regional CO 2 budgets, there is a need to develop new types of observations and modeling approaches.…”