Alteration of rocks by endolithic organisms is one of the pathways for the beginning of soils on Earth

Abstract

Subaerial endolithic systems of the current extreme environments on Earth provide exclusive insight into emergence and development of soils in the Precambrian when due to various stresses on the surfaces of hard rocks the cryptic niches inside them were much more plausible habitats for organisms than epilithic ones. Using an actualistic approach we demonstrate that transformation of silicate rocks by endolithic organisms is one of the possible pathways for the beginning of soils on Earth. This process led to the formation of soil-like bodies on rocks in situ and contributed to the raise of complexity in subaerial geosystems. Endolithic systems of East Antarctica lack the noise from vascular plants and are among the best available natural models to explore organo-mineral interactions of a very old “phylogenetic age” (cyanobacteria-to-mineral, fungi-to-mineral, lichen-to-mineral). On the basis of our case study from East Antarctica we demonstrate that relatively simple endolithic systems of microbial and/or cryptogamic origin that exist and replicate on Earth over geological time scales employ the principles of organic matter stabilization strikingly similar to those known for modern full-scale soils of various climates.

Desert breath—How fog promotes a novel type of soil biocenosis, forming the coastal Atacama Desert’s living skin

“…We conclude that accumulation processes lead to the formation of a terrestrial protopedon with a cryptic A horizon enriched in C and N, as suspected in our third hypothesis. Similar processes of soil formation were reported for Antarctica (Mergelov et al, ), where cyanobacteria and fungi contributed to the formation of soils. This could be a significant contribution to biogeochemical cycles in such organic matter poor desert environments and even to global cycles if we assume that large areas in fog‐influenced deserts may be covered by similar but, to date, undiscovered biocrust types.…”

“…The occurrence of for example lichens as a symbiosis between algae and fungi dates back to the Precambrian 400 million years ago (Taylor & Osborn, 1996), while cyanobacteria are suspected to have played a significant role during early oxygen production and atmospheric enrichment with oxygen even before the Great Oxidation Event (GOE) 2.45-2.32 billion years ago (Lalonde & Konhauser, 2015;Schirrmeister, de Vos, Antonelli, & Bagheri, 2013). Until land plants appeared, about 70 million years ago (Heckman, Geiser, Eidell, Stauffer, Kardos, & Hedges, 2001), the terrestrial organic C pool of early soils as well as the atmospheric oxygen pool was fueled solely by the biological activity of cryptogams for a long geological period (Lalonde & Konhauser, 2015;Mergelov et al, 2018). Assuming that the arid to hyperarid conditions of the Atacama Desert have been stable since the middle Miocene (Sun, Bao, Reich, & Hemming, 2018), the grit-crust community found at the modern coastal Atacama could be a continuation of a very early community type.…”

Nanoscale Observations Support the Importance of Chemical Processes in Rock Decay and Rock Coating Development in Cold Climates

“…Unfortunately, there still exists the assumption by some of "minimal chemical weathering" in cold climates like Antarctica [39]. However, most scholars no longer consider biochemical and chemical rock decay processes as unimportant or even a distant second to physical rock decay, as evidenced by recent research [40][41][42][43][44][45][46][47] and Ph.D. dissertations [48] on cold-climate rock decay not having fight against those prejudiced by the old paradigm.…”

Antarctic cryptoendolithic bacterial lineages of pre-Cambrian origin as proxy for Mars colonization

“…The earliest terrestrial niche for life on Earth were rocks that offered protection from UV-radiation (especially before screening pigments were evolved 1 ), desiccation and other stresses 2 . Porous rocks in particular remain the ultimate refuge for life in harsh environments as in the ice-free areas of Antarctica, where complex life-forms became extinct about 60-30 Ma, when the continent reached the South Pole and the Antarctic Circumpolar Current was established.…”