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 microhabitats.

Key words: food webs, lichen, micro-fauna, microhabitats, mites, tardigrades, Xanthoparmelia