You are here:
CONTROLS ON NUTRIENT LOSSES FROM A FORESTED BASIN IN THE OREGON COAST RANGE
Citation:
Compton, J E., M R. Church, AND S T. Larned. CONTROLS ON NUTRIENT LOSSES FROM A FORESTED BASIN IN THE OREGON COAST RANGE. Presented at Second International Nitrogen Conference, Potomac, MD, October 14-18, 2001.
Description:
Although conceptual models of watershed biogeochemistry emphasize the movement of materials from the land to the sea, important transfers occur in the reverse direction in coastal watersheds through salt spray deposition and returning anadromous fish. To understand the connections between land and sea in the Pacific Northwest, we examined 45 small forested watersheds in coastal Oregon's Salmon River basin. The Oregon Coast Range has very low atmospheric N deposition, but high soil N content and widespread distribution of red alder, an early successional N2-fixing tree. Stream nitrate concentrations ranged from nearly zero to over 3 ppm nitrate-N, and were positively related to proximity to the coast and proportion of the watershed in broadleaf cover (dominated by red alder). Dissolved organic nitrogen concentrations were generally much lower and less spatially variable than nitrate. For watersheds with less than ten percent alder cover, we found a correlation between nitrate and chloride in streamwater, suggesting that chloride deposited in salt spray may displace nitrate and promote leaching. Our work indicates that these watersheds are subject to high N losses, possibly driven by atmospheric deposition of sea salt and maintained by the shifting presence of N2-fixing red alder.