Cryprogamic Soil Crust

What is it?

Cryptogamic soil is a very thin layer of life consisting of a variety composition of living organisms including lichens, bryophytes, algae, fungi, cyanobacteria and mosses. Algae are the most common and abundant of them all due to their adaptive ability, how ever we more closely associate lichens and moss's due to the fact that we can see them much more clearly with out the assistance of a microscope. These organism can play a huge part in stabilizing the top layer of soil (Horizon O). This is hugely beneficial in making sure that erosive forces like wind and water don't crumble away this important layer and leave the bedrock barren. Cryptogamic crust also can help maintain moisture levels and distribute it deeper into the soil layers along with other important processes such as nitrogen fixation. Depending on where the soil crust is located and which scholar you ask, soil crust can either help or not help vascular plants from establishing and flourishing.

The fact that its only a thin layer on the surface, does mean its fragile and easily acceptable to being killed. This can be done by some animal walking over it. Humans hiking up in the mountains has also had a detrimental impact on the population of Soil Crust communities, as hiking has become more economically and physically feasible. Previusly hard to reach or undesirable mountain tops, or deserts have become destination hot spots, and all it takes is one foot step to undo a hundred years of growth.

Sign indicating how important it is to stay to the beaten path! Photo Credit goes to Valley of Fire state park.

Habitat

These types of communities tend to inhabit areas that are arid and semi arid, such as the south western united states, Australia and Antarctica.. Soil Crust communities are highly specialized community of cyanobacteria, mosses, and lichens that along with their biomass and waste products create the Solid crust that cover the surface of otherwise barren landscapes. A huge portion of landscapes Soil Structures begins with these communities.

Cyanobacteria

Cyanobacteria (a.k.a Cyanophyta) are photosynthetic bacteria, and are also the only photosynthetic prokaryotes who can produce oxygen by them selves. (Fun fact, which means they are being studied to try and help the renewable energy goals set by the Paris accord)

They can be found in almost all terrestrial and aquatic ecosystem, the most common of which to be found in Soil Crusts are those in the Micorcoleus genus and Nostoc genus. Which are large filamentous species that from filaments that are covered in Polysaccharides (Polysaccharides are a polymeric carbohydraye molecules). These Polysaccharides are sheaths that stabilize the small layer of soil that the Soil Crust is forming on, thus helping it to accumulate and grow. Eventually becoming thick enough for the next stage of restoration to occur. Unless its at a high elevation (i.e a windy mountain top), where it will not be replaced by the next stage of restoration.

Lichens

Lichens are a composite organism, the consist of many different types on individuals working together for a common goal, survival. Lichen arise from cyanobacteria and/or algae which are all ready living among a fungus in a symbiotic lifestyle. Thus creating a new organism that looks and behaves very different then its "parent" organisms.

They are distinguished by their growth patterns and because of this they can be used to age past events. This is done by measuring their radial size and then based on this we can infer how long that lichen has been growing on that barren rock. Which we can then determine how long that barren rock has been barren and exposed. [[File:|border\200px]]

Lichens are one of the firs living things to start colonizing on barren rock after an event that stripped it of its soil. It starts the process of forming new soil. It does this by releasing acids that break down the rock as it grows over time. This releases rock material and when the lichen dies it is turned into a small layer of soil for the next stage of restoration to occur in. Lichens can also do Nitrogen and carbon fixation, as well as producing a array of different colors due to different pigments they release.

Styles of Lichens

Crustose: These Lichens form a close bond with the surface upon which it is growing on. Forming a biological adhesive layer with the abiotic surface

Foliose: These lichen have the unique ability to change their reproductive habits based purely on environmental stresses. The more disturbances their are, the more they use sexual reproduction. While the more stable the environment is the more they use asexual reproduction.

Squamulose: These lichen are often small overlapping segments called squamules. They are not smooth and on the same plane as the surface they grow on, instead they almost appear bumpy. Squamulose lichen are a inter-median of Crustose and Foliose lichens

Impact

Albedo : Depending on which crust community you look at, they have a range of different colors, which differ from the surface they are growing on. Thus they are changing the albedo of that local area, this can either increase or decrease the local temperature. In most cases it increases it.

They perform ecological functions that benifit the surrounding evnironment.

Soil Stability : The habitats where Soil Crust form are areas where other plant growth is slow and in most places none-existent. Therefore soil growth is slow and soil erosion is high. Where cryptogrammic crust forms it binds, strengths the soil making it just that much harder for it to be eroded away.

Water Infiltration: Cryptogramic Soil Crust communities can affect he regions hydrologic cycle, depending in which type, in a positive or negative way. Including absorbance and retention abilities of the soil, along with soil porosity itself by changes how the rain and runoff water interacts at the surface.

References

1) Anderson, David C., et al. “Factors Influencing Development of Cryptogamic Soil Crusts in Utah Deserts.” Journal of Range Management, vol. 35, no. 2, 1982, p. 180., doi:10.2307/3898386.

2)Lesica, et al. “The Effects of Cryptogamic Soil Crust on the Population Dynamics of Arabis Fecunda (Brassicaceae) /.” Details - The Effects of Cryptogamic Soil Crust on the Population Dynamics of Arabis Fecunda (Brassicaceae) /, Helena, Mt. :Montana Natural Heritage Program,[1991], 1 Jan. 1991, www.biodiversitylibrary.org/bibliography/35812.

3)Ahmadjian, V. The nature of lichens:31-36.

4)Gallery - Utah Lichens, www.tanelorn.us/data/utah_08/gal_utah_bio1.htm.

5)Belnap, Jayne (August 5, 2013). "Cryptobiotic Soils: Holding the Place in Place". U.S. Geological Survey. Archived from the original on May 10, 2016. Retrieved May 10, 2016.

6) Dobson, F.S. (2011). Lichens, an illustrated guide to the British and Irish species. Slough, England: Richmond Publishing Co. Ltd. ISBN 9780855463151.