Bishop Field Office

The desert pavement contains many organisms that must not be overlooked

Desert pavement with Mt. Tom in the distance


Biological crusts, also known as cryptobiotic crusts, are made up of mosses, lichens and cynobacteria (blue-green algae).  These crusts are found throughout the Northern Mojave and Great Basin deserts on a variety of different soil substrates.  Most organisms are found within the first 4 mm of the soil surface and are most easily seen during early spring when soil moisture levels are higher.



Why are these cryptic cryptos so important?

  • They increase the water-holding capacity of the soil
  • They increase nutrient-cycling in the soil
  • They reduce the invasion of weedy, non-native annual grasses
  • They reduce soil erosion - for example, mature crusts can withstand 100 mph ground wind

Biological crusts intermixed in a rocky substrateA disturbance (foot traffic, vehicles, etc.) can loosen and/or weaken the sediment associated with the crusts.  This may have a direct or indirect affect on the disturbed crust or surrounding biological soil crusts.  One example of a direct affect is that the percent nitrogen-fixation is significantly reduced.  The reduction of nitrogen-fixation is due to the movement of cyanobacteria away from the disturbed site and the decrease in numbers of lichen and moss from solar exposure.  One example of an indirect affect is that other surrounding biological communities can be buried from erosion and deposition.  Recovery of biological soil crusts can take a long time and will depend heavily on the intensity of disturbance.

The best way to avoid disturbing these unique soil organisms is by staying on existing trails and roads.  One footprint on untracked soils can destroy a community of cryptogamic crusts for ever