A survey of the old-growth areas of Wachusett Mountain yielded 209 species in 84 genera. This represents higher diversity than for recently well-studied secondary forests in central and eastern Massachusetts. Eighteen old-growth indicator species from northern New England were found on site, somewhat less than the number needed to demonstrate ecological continuity since pre-colonial times. A likely source of disturbance is Industrial Age air pollution, from which the forest may now be recovering. Nonetheless, several species were found during the study that have been rarely collected in Massachusetts (although are not necessarily rare) and a few that may prove to be undescribed. Despite possible disturbance from air pollution, the site appears to serve as a refugium for lichen species that were once more widely distributed in Massachusetts.

Summary of changes since the 1998 report: A survey of the potential old-growth areas reported by Joe Choiniere and Frank Shea for the west side of Wachusett Mountain, plus further investigation of sterile crusts collected previously, resulted in the addition of 59 species and 12 new genera to the total from the study areas. New habitats (e.g. sunny "balds") and substrates (e.g. pitch pines) were responsible for nearly half of the additional species. At least two additional species were found on the west side of the mountain that may prove to be undescribed.

Five additional unidentified lichen taxa are listed at the end of Phil's report; all except no. 2 could not be included in this vouchered checklist:

*sterile sp. no. 1 (norstictic acid)- occasional on pines (a light gray to light brown crust with effuse granular soredia, probably an undescribed Buellia (?) species, known also from Mount Everett)

*sterile sp. no. 2 (unidentified substances) - infrequent on hardwoods (specimens #4264, #4342, #3286, a yellow-green crust with effuse soredia, turning gray with age; unknown to Tor Tønsberg and Richard Harris) [identified later as Pertusaria globularis]

*sterile sp. no. 3 (unidentified substances) - found once on bark of a dead tree (specimen #3291, a yellow-green crust with discrete soralia, turning brown with age)

*sterile sp. no. 4 (unidentified pigment) - found once on sugar maple (specimen #5689B, a gray-green crust with punctiform soralia; possibly a Biatora, but unknown to Christian Printzen)

*sterile sp. no. 5 (stictic acid) - found once on silicic rock (a rimose-areolate crust with discrete soralia, possibly an undescribed Aspicilia; seen by Alan Fryday)