Explains biological soil crusts, organism-produced soil
formations commonly found in semiarid and arid environments,
with special reference to their biological composition, physical
characteristics, and ecological significance. Fact sheet on the
need to protect biological soil crusts in the desert. These
crusts are most of the soil surface in deserts not covered by
green plants and are inhabited by cyanobacterium (blue-green
algae) and other organisms useful to the ecosystem. This website
is a gateway to information and data on Lake Tahoe with links to
Lake Tahoe Initiative, geography, history, lake facts, GIS Data,
DEM, DOQ, DLG imagery, bathymetry, satellite imagery, land
cover, census, soils, pictures, and general maps. Explains 16
distinct types of scientific information that are needed to
understand climate change, including the specific parameters
measured, why they are needed, who measures them, and the type
and amount of information that are not yet available. Guide to
major U.S. environmental statute