Interactions between lichens and lichen-feeding molluscs

Ole Wiggo Røstad

Lichens are long-lived and sessile organisms that dominate habitats where the biomass of plants are generally low. In order to sustain viable populations and complete a life cycle comprising several years, lichens depend on a strong herbivore defence and/or a low nutrition value. Nevertheless, severe grazing damage by snails often occurs in some threatened old forest lichen communities, meaning that the herbivore defence is not always sufficiently effective.

Many lichen species defend themselves against herbivores by producing large quantities of secondary metabolites. We aim to identify factors regulating lichen palatability and their investment in defensive compounds. Such factors may include environmental variables like forest successional stage, nitrogen deposition as well as internal variables like thallus size and reproductive effort.

Furthermore, we aim to quantify the effect of herbivory on epiphytic lichens and lichen communities. Mature and juvenile lichens will be studied as the impact of mollusc grazing may depend on the lichen life stage.

Hosting institution
Norwegian University of Life Sciences (UMB)

PhD student
Johan Asplund, INA, UMB

Project coordinator
Professor Yngvar Gauslaa, INA, UMB

Project collaboration
Professor Knut Asbjørn Solhaug, INA, UMB
Associate professor Torstein Solhøy, UiB
Professor Kristin Palmqvist, Umeå University

Publications

-	Asplund, J. & Gauslaa, Y. 2007. Mollusc grazing limits growth and early development of the old forest lichen Lobaria pulmonaria in broadleaved deciduous forests. – Oecologia 155: 93-99. (Abstract/Fulltext)
-	Asplund, J. & Gauslaa, Y. 2007. Contents of secondary compounds depends on thallus size in the foliose lichen Lobaria pulmonaria. – Lichenologist 39: 273-278. (Abstract/Full text)
-	Nybakken, L., Asplund, J., Solhaug, K.A. & Gauslaa, Y. 2007. Forest successional stage affects the cortical secondary chemistry of three old forest lichens. – J Chem Ecol 33: 1607–1618. (Abstract/Full text)
-	Gauslaa, Y., Holien, H., Ohlson, M. & Solhøy, T. 2006. Does snail grazing affect growth of the old forest lichen Lobaria pulmonaria? – Lichenologist 38: 587-593. (Abstract/Full text)
-	Gauslaa, Y. 2005. Lichen palatability depends on investments in herbivore defence. – Oecologia 143: 94-105. (Abstract/Full text)

Published: 01.10.07
Updated: 01.10.09
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