The geology, microclimate, and biology of a distinctive ecosystem within the sandstone of hyper-arid Timna Valley, Israel

Microbial communities within sandstone rocks in the southern Negev Desert of Israel (e.g., Timna Park) were initially described by Imre Friedmann and Roseli Ocampo-Friedmann in their pioneering study in this region. This endolithic colony, predominantly composed of cyanobacteria species, raises questions about their adaptive mechanisms to harsh local environmental conditions. To provide an adequate context for understanding the environmental challenges that shape the microbial community, we first present an overview of the geological and climatological setting of the Timna site. Subsequently, additional data on the long-term precipitation records for Timna valley, comprehensive multi-year microclimatic data from a colonized site, rock mineralogy, and rock pore structure at this location are presented. Our findings indicate a distinct microbial population adapted to an extremely arid environment, where sporadic precipitation episodes serve as the primary water source. Thus, it may serve as a model system for the study of the expanded pulse-reserve paradigm (EPRP) as applied to microbial ecosystems in arid environments. Consequently, it may enhance our understanding of distinct microbial ecosystems in severe hot and cold deserts and assist in strategizing the hunt for extraterrestrial life.