Monday, February 23, 2015

Biological Soil Crust Restoration?

The biotic soil crust in Red Rock Canyon, Lake Mead National Recreation Area, NV is showing clumps of the dominant moss species, Syntrichia caninervis. Each black dot represents a separate plant. This extreme arid-dwelling moss inhabits the loose sandy soils of the Mojave Desert. [Credit: Alexis Wartelle]
1.  What Biological Soil Crusts (BSC) occur in the desert? Gallery of BSC: from Canyonlands Research Station

Major types (easily observable):
(NB: A misting of water can make crustal organisms more visible...)

Three soil lichens dominate crusts of both the Sonoran and Grea Basin deserts:

Collema: a genus of gelatinous lichen (blackish, jelly-like when moist). First to colonize.

Placidium: a genus of squamulose lichen (discrete rounded flakes, convex or concave). Usually a secondary successional species.

Psora: a genus of squamulose lichen (discrete rounded flakes, convex or concave), a late-successional stage lichen.

Short moss:  Mosses <10mm and="" b="" bryum="" nbsp="" spp.="">Certodon purpureus 
Heterocystic cyanobacteria: (Notoc, Schizothrix)
Large thalloid liverworts:

Source:  Biological Soil Crusts: Ecology and Management.   Technical Reference 1730-2 2001.
2.  Where do BSC occur?
Soils having high electrical conductivity, high phosphorous, and high salt contents facilitate the
formation of cryptogam crusts. Shrink-swell clays (smectites, montmorillonites dervied from volcanic ash) are the worst.

Sonoran and Chihuahan deserts have more heterocystic cyanobacteria lower lichen, but lichen like Collema, Placidium, and Peltula do occur.  Ecoregions that receive summer monsoons (e.g., the Sonoran Desert) tend to have a greater diversity of heterocystic cyanobacteria (such as Lyngbya, Calothrix, Schizothrix, and Nostoc) and lower lichen abundance. Lichens in these areas generally include the gelatinous genus Collema and squamulose genera Placidium and Peltula.  Large thalloid liverworts are more common in warm deserts than cool deserts.

Sonoran:  heterocystic cyanobacteria (Notoc, Schizothrix), gelatinous (nitrogen-fixing) lichens (e.g. Collema), squamulose lichens, short mosses
Chihuahan:  heterocystic cyanobacteria (Notoc, Schizothrix), short moss

3. Resources for mapping BSC distribution?

Map shrink/swell clays!
Some mosses are on Seinet
Lichen image gallery (from Europe) organized by structure.
Lichens on LichenPortal
Lichens on iNaturalist
USFS Database

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