STUBBS, CONSTANCE S. Department of Biological Sciences, University of Maine, Orono, ME 04469. - Long-term biomonitoring (1988--1998): lichen distribution, abundance, and health on red spruce, Picea rubens Sarg.
Lichens are useful bioindicators of environmental quality. Lichen
mapping, one of the oldest biomonitoring techniques, examines the
distribution and abundance of lichens. Lichen mapping provides a
direct measure of lichen health and an indirect measure of air quality
within ecosystems. In environments with poor air quality, pollution
intolerant species become depauperate, extinct, or replaced with
pollution tolerant species. Lichen diversity, abundance, and external
health (based on "normal" thallus morphology, color, and
lichen prevalence) have been monitored in permanent study quadrats on
the boles of red spruce, Picea rubens, at one inland
(University of Maine Experimental Forest) and three coastal sites
(Small Point, Isle au Haut, Roque Island) in Maine every two years
since 1988. Baseline (1988) measurements demonstrated intra- and
intersite differences in presence, abundance, and external health and
suggested that lichens were less healthy at Small Point and the inland
site and more healthy at Isle au Haut and Roque Island. Hypogymnia
physodes was the most prevalent species at all sites. Overall, 27
macrolichen species have been found in study quadrats. Red spruce at
Roque Island has had the greatest diversity: 23 lichen species in
1988, but only 16 species in 1998. Over the 10-year biomonitoring
period, local extirpations of pollution intolerant species outnumbered
new recruits except at the inland site. By 1998, Small Point, the site
closest to the northeast urban-industrial corridor, had the greatest
relative negative change in lichen diversity, abundance, and external
health. In contrast, only the inland site showed relative positive
change. The trends manifested after the initial baseline measurements
demonstrate the value of long-term biomonitoring for better
understanding the distribution and abundance patterns of lichens.
Key words: Hypogymnia physodes , Picea rubens , biomonitoring, diversity, lichens, pollution