Sandling, Aron, 2010. Distribution and nitrogen fixation of terricolous lichens in a boreal forest fire chronosequence. First cycle, G2E. Umeå: SLU, Dept. of Forest Ecology and Management
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Abstract
Given that nitrogen (N) is a limiting nutrient in boreal ecosystems, biological N fixation can have a large influence on primary production and other processes in this ecosystem. To date, most studies focused on N fixation in boreal ecosystems have focused on bryophyte-cyanobacteria associations, whereas relatively few studies have investigated the significance of N fixation by lichens. In this study I examined how biomass and aerial N fixation rates of two common terricolous lichens, Nephroma arcticum (L.) Torss. and Peltigera aphthosa (L.) Willd., varied across a boreal chronosequence, where time since fire varied from 43 to 362 years. The main objective of the study was to observe how stand age influenced biomass and N fixation rates of terricolous lichens, which has been extensively described in previous studies for bryophyte-cyanobacteria associations. The study revealed that biomass and consequently N fixation rate per unit area for both lichen species significantly increased with time since fire; whereas, lichen N fixation rates per unit mass was unaffected by stand age. Peltigera aphthosa, but not N. arcticum, demonstrated a significantly higher N fixation rate per unit biomass than the Pleurozium-cyanobacteria association. However, on a per unit area basis, both lichen species demonstrated several orders of magnitude lower N fixation rates relative to the Pleurozium-cyanobacteria association, which was largely driven by differences in biomass per unit area of lichens and bryophytes. This study demonstrates that lichen biomass and N fixation rates per unit area respond positively to the long term absence of wildfire, and further suggest that the contribution of lichens to total forest N fixation rates is minor relative to bryophytes.
Main title: | Distribution and nitrogen fixation of terricolous lichens in a boreal forest fire chronosequence |
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Authors: | Sandling, Aron |
Supervisor: | Gundale, Michael |
Examiner: | Nilsson Hegethorn, Marie-Charlotte |
Series: | Examensarbeten / SLU, Institutionen för skogens ekologi och skötsel |
Volume/Sequential designation: | 2010:01 |
Year of Publication: | 2010 |
Level and depth descriptor: | First cycle, G2E |
Student's programme affiliation: | None |
Supervising department: | (S) > Dept. of Forest Ecology and Management |
Keywords: | Succession, Fire chronosequence, Nitrogen fixation, Boreal forests, Lichens, Peltigera aphthosa, Nephroma arcticum |
URN:NBN: | urn:nbn:se:slu:epsilon-2-303 |
Permanent URL: | http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-2-303 |
Subject. Use of subject categories until 2023-04-30.: | Plant ecology Forestry - General aspects |
Language: | English |
Deposited On: | 04 Mar 2010 08:37 |
Metadata Last Modified: | 20 Apr 2012 14:11 |
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