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Updated: May 6, 2026

BtM, a Low-cost Open-source Datalogger to Estimate the Water Content of Nonvascular Cryptogams
Published on: March 25, 2019
Water relations and photosynthesis in the cryptoendolithic microbial habitat of hot and cold deserts
1Polar Desert Research Center and Department of Biological Science, Florida State University, 32306-2043, Tallahassee, Florida, USA.
Abstract:
Two cryptoendolithic microbial communities, lichens in the Ross Desert of Antarctica and cyanobacteria in the Negev Desert, inhabit porous sandstone rocks of similar physical structure. Both rock types adsorb water vapor by physical mechanisms unrelated to biological processes. Yet the two microbial communities respond differently to water stress: cryp-toendolithic lichens begin to photosynthesize at a matric water potential of -46.4 megaPascals (MPa) [70% relative humidity (RH) at 8°C], resembling thallose desert lichens. Cryptoendolithic cyanobacteria, like other prokaryotes, photosynthesize only at very high matric water potentials [> -6.9 MPa, 90% RH at 20°C].
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