Lichen Growth Responses to Stress Induced by Automobile Exhaust Pollution

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Science  27 Apr 1979:
Vol. 204, Issue 4391, pp. 423-424
DOI: 10.1126/science.204.4391.423


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.