LEWIS, L.A.*, J. JOHANSEN, V. FLECHTNER, AND L. ST. CLAIR. Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT 06268-3043. - Biotic Crust Project: Survey of the algae, lichens, and mosses of microbiotic crusts of selected arid and semi-arid sites in Western North America.
Biotic crusts communities occur in arid and semi-arid habitats
world-wide, and include taxa such as cyanobacteria, eukaryotic
"algae", fungi, lichens and bryophytes. The ecological role
of crusts includes soil stabilization and nutrient cycling, and there
is great interest in the effects of disturbance on crust communities.
Despite interest in the ecological role of crusts, very little is
known about their taxonomic composition. A survey of the
photosynthetic organisms from thirty crust sites in western North
America is currently underway. Lichens and bryophytes are assessed
directly from collected material, while the cyanobacteria and green
algae are isolated from serial dilution cultures. A majority of sites
have been collected, but only a small number of sites have data for
all taxonomic groups. To date, 45 lichen taxa, 78 cyanobacterial taxa,
and 80 green algal taxa have been identified. This number is likely to
go up, especially for the cyanobacteria and green algae, as more
samples are processed. In addition to the taxonomic survey, soil
chemistry data are being collected. These data may be useful in
assessing which ecological factors are influencing the distribution of
crust taxa.
Key words: biotic crust, Chlorophyta, cyanobacteria, desert, rDNA