UNdERSTANdINg PARk RESOURCE INTERACTIONS ON AN ECOLOgICAL BASIS 39 Twenty-four years of Great Lakes lichen studies provide park biomonitoring baselines

fOR the Past 24 yeaRs, BIOlOgIsts haVe studied lichens in the Great Lakes national park units in considerable detail (see map), including floras and chemical element surveys, for biodiversity and air quality assessments. They have studied lichens because they are sentinel species indicating ecosystem health, and because they are excellent biomonitoring and bioindicator species of air quality. These studies have been funded by individual parks, the NPS Air Resources Division, and the U.S. Geological Survey.