USGS Soil Carbon Research @ Menlo Park
| what's new | research | areas | people | products | networks |
| background | ||
Kanuti Flats geocover. Click on the photo for an enlarged image. |
The Boreal Forest contains about 1/3 of all global terrestrial carbon stored as
vegetation and soil organic matter. The fate of this carbon, however, is uncertain
because of the widespread degradation of permafrost and the key role of permafrost
in sequestering soil carbon. If the climate warms another 5 to 8 °C in Alaska, as
predicted by the IPCC (2001), nearly all of the permafrost will be eliminated,
causing dramatic changes in water and carbon balance of boreal ecosystems. The effects of permafrost degradation (thermokarst) on surface water and carbon is highly uncertain because of the variability in terrain, topography, vegetation, fire regimes, and permafrost characteristics. While field studies have begun to recognize the importance of thermokarst in carbon accumulation and methane emissions, current modeling approaches still assume a fairly homogeneous soil landscape where thawing lowers the permafrost table and dries the soils. This assumption probably holds well for permafrost-affected upland areas (23% of boreal landscape in Alaska), but is not valid for lowlands areas (41% of landscape), where thermokarst impounds water. Furthermore, the degradation of permafrost affects the export of carbon very differently in upland and lowland landscapes. In upland landscapes the loss of permafrost and increased drainage eliminates surface runoff and alters the seasonality of runoff. In contrast, thermokarst in lowland landscapes impounds water into isolated wetlands, disrupts drainages, greatly increases storage capacity that reduces runoff, and increases the residence time of dissolve organic carbon in isolated wetlands. Thus, current approaches to modeling carbon dynamics neglect the varying modes that permafrost degradation has on water and carbon loss and accumulation across the landscape. back to the Carbon and Water project page... |
|
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://carbon.wr.usgs.gov/carbonandwater_background.html
Page Contact Information: Kristen Manies
Page Last Modified: Friday, 07-Nov-2008 18:20:07 EST
