The goal of this paper was to explore trade-offs between fecundity and carbon based secondary metabolites (CBSM) production within the thallus of three species of Rock-shield and Ring lichens, Arctoparmelia centrifuga, Xanthoparmelia viriduloumbrina and X. cumberlandia. Fecundity was measured by numbers of apothecia per thallus, number of spores per apothecium and percent spore germination, and it was compared with the quantity of the major CBSMs produced by the thallus. Results showed negative correlations between stictic acid and all three measures of fecundity for X. cumberlandia, which are consistent with trade-offs. When thallus and apothecium quantities of CBSMs were compared, stictic acid was the only CBSM with levels in the apothecium that were significantly higher than those in the thallus supporting a function that may protect ascospores against herbivory. Other CBSMs are hypothesized to have functions associated with the thallus and UV protection of green algae.