HR: 1340h
AN: H13F-1386    [Abstracts]
TI: Milti-scaled studies of watershed characteristics within the Tongass National Forest, Southeast Alaska
AU: * Edwards, R T
EM: rtedwards@fs.fed.us
AF: Pacific Northwest Research Station, USDA Forest Service, 2770 Sherwood Lane, Suite 2A, Juneau, AK 99801 United States
AU: D'Amore, D V
EM: ddamore@fs.fed.us
AF: Pacific Northwest Research Station, USDA Forest Service, 2770 Sherwood Lane, Suite 2A, Juneau, AK 99801 United States
AU: Hood, E
EM: eran.hood@uas.alaska.edu
AF: Natual Sciences Department, University of Alaska Southeast, 11120 Glacier Highway, Juneau, AK 99801 United States
AU: Fellman, J B
EM: jfellman@fs.fed.us
AF: Pacific Northwest Research Station, USDA Forest Service, 2770 Sherwood Lane, Suite 2A, Juneau, AK 99801 United States
AU: Norberg, E C
EM: enorberg@fs.fed.us
AF: Pacific Northwest Research Station, USDA Forest Service, 2770 Sherwood Lane, Suite 2A, Juneau, AK 99801 United States
AU: Biles, F E
EM: fbiles@fs.fed.us
AF: Pacific Northwest Research Station, USDA Forest Service, 2770 Sherwood Lane, Suite 2A, Juneau, AK 99801 United States
AB: The Tongass National Forest (Tongass), in Southeast Alaska, is the largest temperate maritime, rainforest in North America. It covers an area of 68,798 km², stretches over 6 degrees of latitude, encompasses over 5,000 anadramous salmon reaches, and includes over 70 ecoregions, associated with several major geologic terranes. Wetlands dominate this wet region, comprising about 30% of terrestrial area. The region is currently experiencing climate change with potentially profound impacts on wetland soil processes, forest structure, stream productivity and the large and valuable salmon fishery. Because of the size and remoteness of the forest, there are little data on stream chemistry, biological productivity, or discharge. To better predict the impacts of climate change, forest practices, or land use change on stream productivity, we require much better baseline data on naturally occurring variability in watershed and stream characteristics and the major biophysical drivers that control stream biogeochemistry. Our efforts to develop a systematic understanding of watershed types and responses include studies at three spatial, temporal and organizational scales. One study is aimed at developing a process-based understanding of how major wetland and vegetation types influence stream chemistry, particularly dissolved organic carbon, through hydrologic coupling and carbon, nitrogen and phosphorus transport. This study is restricted to paired or longitudinal watershed studies with intense sampling frequency and a broad array of detailed measurements. Costs are high and the generality of the results are implied but not confirmed. A second study, of intermediate temporal and spatial scale seeks to identify broader patterns in stream chemistry among three common Tongass stream types within the vicinity of Juneau, Alaska: glacial, brownwater and clearwater. This study has confirmed that these broad stream classes respond differently on a seasonal basis but provides no explanatory sub catchment information. A final study seeks to characterize stream chemistry in a statistically selected population of streams across the entire Tongass. This temporally sparse but spatially extensive scale allows us to correlate broad-scale landscape and watershed characteristics with stream nutrient chemistry. Combined, the three approaches allow us to scale up from the intensive, reach-based studies to a much broader scale with increased confidence, and also to better understand how Tongass-wide landscape variability may constrain the response of individual watershed to natural and anthropogenic change. This spatially and temporally hierarchical approach allows us to maximize the detail and relevance of data collected while minimizing the labor and travel costs associated with such a large area.
DE: 0428 Carbon cycling (4806)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0458 Limnology (1845, 4239, 4942)
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
SC: Hydrology [H]
MN: Fall Meeting 2005