Short-term effects of enhanced UV-B and CO 2 on lichens at different latitudes

• Published in: The Lichenologist (London) 1995-11, Vol.27 (6), p.547-557
• Main Authors: Sonesson, M., Callaghan, T.V., Björn, L.O.
• Format: Article
• Language: English
• ISSN: 0024-2829; 1096-1135
• DOI: 10.1016/S0024-2829(95)80013-1

Interaction effects of UV-B and CO 2 on three lichens species, Cladonia arbusculo, Cetraria islandica and Stereocaulon paschale, from two latitudinal sites, 68∘N and 56∘N, were studied in a laboratory experiment. The response of the plants was recorded by measuring their chlorophyll fluorescence. All species had a similar response to enhanced UV-B depending on the latitude from which the population came and the time of the season when they were sampled. Overall, there was a significant increase in photosystem II yield (as measured by a fluorescence technique) due to UV-B and no separate effect due to enhanced CO 2, although there was a significant interaction between CO 2 and UV-B. The increase due to UV-B was at the low CO 2 level. There were also significant differences in response due to latitude. The results contradict our hypotheses that negative effects of UV-B would be larger in the North than in the South and that a negative response should be especially large during the early season.