TRIPP, BRADLEY B. AND JOHN C. MOORE.* Department of Biological Sciences, University of Northern Colorado, Greeley, CO 80639. - Food webs in saxicolous lichens (Xanthoparmelia ssp.) a comparison of lichen, litter, and soil microhabitats.
We examined the effect of productivity and elevation on micro-fauna
communities within saxicolous lichens (Xanthoparmelia spp.),
adjacent litter, and soil habitats. Productivity was indexed by
lichen colony size (cm 2). Species diversity in the three
habitat types was calculated. Lichen communities were significantly
different than litter and soil microhabitats (p<0.05). Bacterial,
fungal, protozoan (flagellates, amoebae, ciliates), and nematode
densities were significantly lower than that of litter and soil.
While tardigrades, rotifers, mites (mesostigmatid, and
cryptostigmatid), and diplopoda densities were significantly higher
than adjacent litter and soil microhabitats. For example, mean
tardigrade density in lichens was 10.39 per gram dry weight, while
litter density was 0.98/gdw and soil density was 0.47/gdw. Total mean
micro-arthropod density in lichens was 5.347.91/gdw, while the means
were 1.562.06/gdw and 1.24+1.53/gwd for litter and soil respectively.
There was no significant differences in collembola and prostigmatid
mite densities. Neither productivity nor elevation appeared to
influence species diversity within lichen communities. Lichen colony
size was not correlated with micro-fauna density. We present a food
web that describes the community within saxicolous lichen of the genus
Xanthoparmelia in Colorado. Additional micro-fauna included
thrips, ants, symphylans, dipterians, pseudoscorpions and beetles.
While further research needs to be conducted, it does not appear that
saxicolous lichens are distinct communities but rather they represent
elements of both adjacent litter and soil communities. They may
represent both sources and sinks of these organisms to adjacent
Key words: food webs, lichen, micro-fauna, microhabitats, mites, tardigrades, Xanthoparmelia