Abstract
SummaryBioweathering mediated by microorganisms plays a significant role in biogeochemical cycles on global scales over geological timescales. Single processes induced by specific taxa have been described but could rarely be demonstrated for complex communities that dominate whole landscapes. The recently discovered grit crust of the coastal Atacama Desert, which is a transitional community between a cryptogamic ground cover and a rock-bound lithic assemblage, offers the unique chance to elucidate various bioweathering processes that occur simultaneously. Here, we present a bioweathering scenario of this biocenosis including processes such as penetration of the lithomatrix, microbial responses to wet-dry cycles, alkalinolysis, enzyme activity, and mineral re-localization. Frequently occurring fog, for example, led to a volume increase of microorganisms and the lithomatrix. This, together with pH shifts and dust accumulation, consequently results in biophysical breakdown and the formation of a terrestrial protopedon, an initial stage of pedogenesis fueled by the grit crust.
Highlights
Development of terrestrial ecosystems often includes interactions between cryptogamic lithobiontic communities, the lithomatrix of rocks and the given climatic conditions (Mergelov et al, 2018; Mitchell et al, 2019)
Lithobiontic communities are still well known from arid environments such as the Atacama Desert (Azua-Bustos et al, 2011), where external surfaces of hard rocks and cracks and fissures may be conquered by microorganisms using bioreceptive characteristics of the internal rock structure (Wierzchos et al, 2015)
The alteration and transformation of the lithomatrix by metabolism and bioweathering processes of phototrophs can be expected (Weber et al, 2011). This was described for extreme habitats such as Antarctica or ancient Mayan buildings (Ortega-Morales et al, 2016) and similar interactions are very likely to occur in the Atacama Desert, but reports are still missing
Summary
Development of terrestrial ecosystems often includes interactions between cryptogamic lithobiontic communities (cyanobacteria, green algae, lichens, and fungi together with other heterotrophic organisms), the lithomatrix of rocks and the given climatic conditions (Mergelov et al, 2018; Mitchell et al, 2019). Single processes of biogeophysical and biogeochemical weathering by (cyano-)bacteria, green algae, lichens, and fungi are well studied (reviewed in Salvadori and Municchia, 2016; Chen et al, 2000) This includes, e.g., the biological transformation of clay minerals, e.g. by K depletion of interlayers of mica/illite and oxidation of structural Fe(II) of less weathering resistant silicates such as biotite as well as the dissolution of phosphate salts such as apatite (Smith, 1978; Wierzchos and Ascaso, 1998; Chen et al, 2000).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
