title: Lichen growth responses to stress induced by automobile exhaust pollution.
abstract: Growth rates were significantly suppressed in juvenile thalli (less than 0.1 square millimeter in initial size) of the saxicolous lichen Pseudoparmelia baltimorensis from a Potomac River island with high atmospheric lead burden as compared to the case for a similar island with a lower lead burden. However, larger thalli showed no significant changes in growth response as a result of atmospheric pollution stress. Disruptions in lichen growth thus appear to affect life stages when growth is most rapid andfood reserves are low. Once a minimnum thallus size is attained, the stress tolerance of the lichen increases.
authors.forename: J D
authors.initials: JD
authors.lastname: Lawrey
authors.forename: M E
authors.initials: ME
authors.lastname: Hale