Original Research

Photosynthetic performance of rock-colonising lichens in the Mountain Zebra National Park, South Africa

Dirk Wessels, Ludger Kappen
Koedoe | Vol 36, No 1 | a360 | DOI: https://doi.org/10.4102/koedoe.v36i1.360 | © 1993 Dirk Wessels, Ludger Kappen | This work is licensed under CC Attribution 4.0
Submitted: 16 September 1993 | Published: 16 September 1993

About the author(s)

Dirk Wessels, University of the North, South Africa
Ludger Kappen, der Uniyersitdt Kiel, Germany

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Abstract

The photosynthetic behaviour of endolithic andepilithic lichens characteristic of sedimentary and volcanic rock was investigated in situ in the Mountain Zebra National Park, South Africa. The park forms part of an inland semi-desert known as the Karoo, in the Cape Province. Temperatures within Balfour sandstone were monitored, the results showing that during the early morning, temperatures within the sandstone were nearly 5@C lower than ambient air temperatures. This may enhance the frequency of water condensing on the sandstone, which may be particularly important for the endoliths Leciclea aff. sarcogynoides and Sarcogyne cf. austroafricana. Maximum photosynthetic rates of the investigated species were found at temperatures between 20@C and 30@C, far higher than the recorded optimum temperatures for lichens from temperate and desert regions. Parmelia chlorea was the most productive species. Compared to the other epiliths, Peltula capensis was found to be a moderately productive species. The photosynthetic gain of Leciclea aff. sarcogynoides and Sarcogyne cf. austro-africana was low, but the photosynthetic gain of these two species still exceeded that of Acarospora sp.

Keywords

Lichens, endolithic, photosynthesis, sandstone, micro-climate. Karoo.

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