State of the Carbon Cycle in Terrestrial Wetlands of North America
Abstract
Because carbon (C) density of terrestrial wetlands is much greater than that of upland ecosystems, consideration of C stocks and fluxes along with associated changes resulting from management or land-use change are of particular importance at local, regional and global scales. Through new analyses of recent available data bases and literature, C stocks, net ecosystem exchange (NEE) and methane (CH4) fluxes were estimated for North American (US, Canada, Mexico and Puerto Rico) terrestrial wetlands (excluding tidal wetlands or permafrost areas). North America contains approximately 2.2 million km2 of terrestrial wetlands (approximately 37% of the global wetland area) with an ecosystem C pool of approximately 161 Pg (approximately 36% of global wetland C stock). Canada has the greatest area of terrestrial wetlands (52%), followed by the US (47%), Mexico (1%) and Puerto Rico. Likewise, Canada has the largest C stocks, NEE, and CH4 fluxes (80%, 51%, and 57%, respectfully) followed by the US (19%, 43%, and 39%, respectfully) and Mexico (1%, 7%, and 4%, respectfully). Forested wetlands comprise 55% of the total terrestrial wetland area, with the vast majority occurring in Canada. Organic-soil wetlands comprise 58% of the total terrestrial wetland area and contain 80% of the C stock. Overall, North American terrestrial wetlands currently are a CO2 sink (i.e., negative NEE) of approximately 126 Tg of C per year, with approximately 53% occurring in forested- and 51% in mineral-soil wetlands. However, North American terrestrial wetlands are a natural source of CH4, with mineral-soil wetlands emitting 56% and non-forested wetlands emitting 55% of the estimated total of 45 Tg CH4 -C per year. The current rate of terrestrial wetland loss is much less than historical rates (about 0.06% of the wetland area from 2004 to 2009), with restoration and creation nearly offsetting losses of natural wetlands. Although area losses are nearly offset, there is considerable uncertainty about the functional equivalence of disturbed, created, and restored wetlands compared to undisturbed, natural wetlands. For this reason, studies and monitoring systems are needed that compare C pools, rates of C accumulation and greenhouse gas fluxes across disturbance gradients, including restored and created wetlands.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B43C..11K
- Keywords:
-
- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSESDE: 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 4806 Carbon cycling;
- OCEANOGRAPHY: BIOLOGICAL AND CHEMICALDE: 6309 Decision making under uncertainty;
- POLICY SCIENCES