Some ecophysiological properties of cyanobacterial cryptobiotic crusts of tropical desiccation-tolerant vegetation

Abstract

Our results indicate that the cryptogamic inselberg crusts from Tanzania and French Guyana indicate an extremely high degree of desiccation-tolerance. They are able tolerate not even a few days or weeks but 1 year (the Tanzanian sample) or 5 years (the French Guyana sample) desiccated stage. They can regain their maximum CO2 assimilation rate within 15–20 min (Tanzanian) and 45–50 min (French Guyana) after rehydration, respectively. The measured net CO2 assimilation rate of the cyanobacterial inselberg crusts from both the African and South-American habitat were similar to the rates reported on other non-inselberg and non-tropical cryptogamic cryptobiotic crust vegetations such as vegetations covered by lichens or mosses (Larcher, 2003; Juhasz et al., 2005). The success of the studied two tropical inselberg cryptogamic crusts to adaptation and CO2 assimilation on exposed rock surfaces is due to their special ecophysiological abilities. Concerning this above C-assimilation capacity of the tropical inselberg cryptogamic crusts and the significant occurrence of the tropical/sub tropical inselberg covered by cyanobacterial crusts even in a global scale (Porembski and Barthlott, 2000), it can conclude that these inselberg crusts have a considerable carbon pool and they contribute significantly to the global carbon cycling of the Earth.