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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
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
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
Subjects: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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