PHYSIOLOGICAL‐ENVIRONMENTAL INTERACTIONS IN LICHENS X. LIGHT AS AN ECOLOGICAL FACTOR

Abstract

Little attention has been paid to the potential importance of light in the ecology of lichens. Data is presented which shows that Peltigera canina var. praetextata from a woodland floor can rapidly acclimate to low or high light levels and thus maintain a given level of photosynthesis irrespective of the leaf canopy status. This photosynthetic adjustment takes place naturally in the field during leaf fall in October. P. scabrosa shows a similar response to low light and furthermore, acclimation to low levels of illumination can readily take place in air‐dry material. In contrast populations of Peltigera aphthosa collected from the dense shade of spruce in northern Ontario are extremely sensitive to quite modest levels of ‘high’ light, with pronounced damage occurring under 350 μE m‐3 8‐1 illumination. Contrasting populations of P. aphthosa collected from open habitats are not affected by this level of illumination. The maintenance of the correct day length during air‐dry storage is also very important since a rapid alteration of daylength produces a marked although temporary photosynthetic decline. On the other hand continuous daylight induces a rapid and continuous decline of photosynthesis probably leading eventually to the death of the phycobiont. Copyright © 1980, Wiley Blackwell. All rights reserved