Nitrogen cycling in a subarctic Alaskan watershed: the role of lichens and the potential effects of acid deposition
Gunther AJ. 1987. Nitrogen cycling in a subarctic Alaskan watershed: the role of lichens and the potential effects of acid deposition. University of California Berkeley
This thesis investigates (1) the importance of nitrogen-fixing lichens to the nitrogen cycle of the Brooks Lake drainage, a nitrogen-limited nursery lake for sockeye salmon, and (2) the sensitivity of nitrogen fixation by lichens to simulated acid deposition. Fieldwork took place during the summers of 1984 through 1986. Biological nitrogen fixation was found to be the major source of new nitrogen in the Brooks Lake drainage, at a rate of approximately 3 kg N/ha-yr. This compares to 0.3 kg N/ha-yr in precipitation and 0.02 kg N/ha-yr in returning adult salmon. The low levels of nitrogen in precipitation, combined with a lack of nitrogen-fixation activity in open lakes, indicates that nitrogen in tributary streams is the major source of new nitrogen in Brooks Lake drainage. Dose-response experiments indicate that the major genus of nitrogen-fixing lichens in the drainage is not sensitive to acid deposition, one of the more important forms of air pollution in remote regions.
- Type
- Academic
- Authors
- Gunther, Andrew
- Date of Issue
- 1987
- Publisher
- University of California Berkeley
- Units
- KATM
- Keywords
- Acid Deposition, Acid Rain, Air Pollution, Brooks Lake, Brooks Lake drainage, Dissertation, Dumpling Mountain, Katmai National Park And Preserve, Lakes, Lichen (Mycophycophyta), Nitrogen Fixation, Plants, Pollution, Productivity, Water Chemistry