摘要：

A cryptoendolithic cyanobacterial habitat is described from Tshipise Sandstone in a dry savannah ecosystem in the Northem Province, Southafrica. The community consisted of a species of the genus Chroococcidiopsis, which represented the dominating organism, the species Nostochopsis lobatus, which was the first time for it to be found in an endolithic habitat, and the species Microcoleus cf sociatus, as weH as microfungi belanging to the Deuteromycetes. Temperature conditions inside the cyanobacterial zone were not evidently different from rock surface temperatures, whereas the water conditions appeared to be by far more favourable inside the sandstone. The light factor was found to be the essential [actor promoting endo]ithic growth. Light saturation of the photosynthetical electron transport rate was reached at an intensity of 200-300).lmo] m-2 S-1 PPFD (Photosynthetic Photon Flux Density). This coincided cJearly with the light intensities within the cyanobacterial zone. In an experimental reproduction of the habitat, it could be shown, that the depth adjustment ofthe cyanobacterial community is a light regu]ated process, depending on the light intensity. The colonization density of the cryptoendolithic habitat, expressed as ch]orophyHa ranged between 0.05 and 7].8 mg m-2, C-values ranged between 4 and 107 mg m-2, and the N-values covered the range from 0.7 to 4.4 mg m-2.

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