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

Abstract

The Atacama Desert is the driest non‐polar desert on Earth, presenting precarious conditions for biological activity. In the arid coastal belt, life is restricted to areas with fog events that cause almost daily wet–dry cycles. In such an area, we discovered a hitherto unknown and unique ground covering biocenosis dominated by lichens, fungi, and algae attached to grit‐sized (~6 mm) quartz and granitoid stones. Comparable biocenosis forming a kind of a layer on top of soil and rock surfaces in general is summarized as cryptogamic ground covers (CGC) in literature. In contrast to known CGC from arid environments to which frequent cyclic wetting events are lethal, in the Atacama Desert every fog event is answered by photosynthetic activity of the soil community and thus considered as the desert's breath. Photosynthesis of the new CGC type is activated by the lowest amount of water known for such a community worldwide thus enabling the unique biocenosis to fulfill a variety of ecosystem services. In a considerable portion of the coastal Atacama Desert, it protects the soil from sporadically occurring splash erosion and contributes to the accumulation of soil carbon and nitrogen as well as soil formation through bio‐weathering. The structure and function of the new CGC type are discussed, and we suggest the name grit–crust. We conclude that this type of CGC can be expected in all non‐polar fog deserts of the world and may resemble the cryptogam communities that shaped ancient Earth. It may thus represent a relevant player in current and ancient biogeochemical cycling.

Biodiversity of Algae and Cyanobacteria in Biological Soil Crusts Collected Along a Climatic Gradient in Chile Using an Integrative Approach

“…Just like in Africa, the Chilean biocrusts were devoid of cyanolichens [ 35 ], with cyanobacterial members confined to hypolithic habitats [ 51 , 63 ]. Jung et al [ 28 ] described “grit crust”, a transitional form between rock cover and soil crust in a classical sense. Grit crusts are communities consisting of fungi, cyanobacteria and algae, formed on top of singular grit-sized quartz and granitoid stones, which cover and connect the grit-sized rocks.…”

“…Several new cyanobacteria were recently described from the Atacama Desert: Kastovskya, Symplocastrum, Myxacorys, Trichocoleus and Oculatella species [ 23 , 24 , 25 , 26 , 27 ]. The most recent is a study by Jung et al [ 28 ] which investigated the diversity of hypolithic and edaphic cyanobacteria in two study areas, hyperarid Pan de Azúcar and the semiarid area of the Nature Reserve Santa Gracia; the authors reported 21 cyanobacterial species and the new species Aliterella chasmolithica [ 29 ].…”

Novel Lichen-Dominated Hypolithic Communities In the Namib Desert

“…Previous research has reported that the distribution of terricolous lichens in this desert depends on factors such as distance to the coast, elevation, climatic gradients, wind and sand force, substrate and physiological adaptations [25,47]. The extensive growth of epilithic and crust forming coastal lichens is thought to be supported by moisture content derived from fog and dew [22,23,48]. Water availability has also been considered an important determinant in shaping hypolithic microbial community structure along an inverse fog-…”

Novel lichen-dominated hypolithic communities in the Namib Desert

“…Previous research has reported that the distribution of terricolous lichens in the Namib Desert depends on factors such as distance to the coast, elevation, climatic gradients, wind and sand force, substrate, and physiological adaptations [25,47]. The extensive growth of epilithic and crust forming coastal lichens is thought to be supported by moisture content derived from fog and dew [22,23,48]. Water availability has also been considered an important determinant in shaping hypolithic microbial community structure along an inverse fog-rainfall gradient across the central Namib Desert [4].…”