Nitrogen Fixation by Lichens in a Subarctic Alaskan Watershed
Gunther AJ. 1989. Nitrogen Fixation by Lichens in a Subarctic Alaskan Watershed. The Bryologist. 92(2):202-208
(Author's abstract.) Measurements of lichen biomass and nitrogenase activity were used to estimate the annual nitrogen fixation by lichens in the watershed of Brooks Lake. These measurements, when combined with the areal extent of different habitats as determined from satellite photos and conversion ratios relating short-term acetylene reduction measurements to long-term nitrogen fixation rates, produced a best estimate for nitrogen fixed by lichens of 0.1 kg N ha-1 yr.-1. The uncertainty in this calculation, however, suggests a more reasonable estimate of nitrogen fixation by lichens to be a range of 0.04-0.21 kg N ha-1 yr.-1, although in a moist habitat where nitrogen-fixing lichens are abundant they may contribute up to 0.94 kg N ha-1 yr.-1. Even in this ecosystem remote from anthropogenic influences, the contribution of fixed nitrogen by lichens is less than that from precipitation and an order of magnitude below nitrogen fixed by Alnus trees, implying that at the watershed level lichens will only be important contributors of fixed nitrogen in moist, remote ecosystems where the abundance of nodulated plants is limited.
- Type
- Journal Article
- Authors
- Gunther, Andrew
- Units
- KATM
- Keywords
- Biomass, Brooks Lake watershed, Katmai National Park And Preserve, Lichen (Mycophycophyta), Nitrogen Fixation, Plants