Summary
1.Respiration in eight lichen species was related to thallus hydration status, externaltemperature and to total nitrogen, chitin and ergosterol concentrations. Chitin is anitrogenous and major compound of the fungal cell wall, and ergosterol is a sterol ofthe plasma membrane in fungi and sometimes in algae.2.Hydration of previously dry thalli resulted in an initially high rate of respiration.Both the amplitude of this resaturation respiration and the time required to reachsteady state varied among species. Generally, peak rates were one to three times higherthan steady-state rates, which were reached 3–7 h after hydration.3.Increases in external temperature also resulted in transient bursts in respiration.Again, both the amplitude of the burst and the time required to reach steady statevaried among species. Also depending on species, a temperature increase from 5 to 15 °Cresulted in two- to fivefold increases in steady-state respiration.4.Steady-state respiration, at optimal thallus hydration and a given temperature,varied three- to sixfold among the species, when related to thallus dry mass. This dif-ference correlated best (r2= 0·89) with their ergosterol concentration, where adoubling in ergosterol resulted in more than a doubling in respiration. Respirationcorrelated less well to total nitrogen or chitin.5.The chitin to ergosterol ratio varied more than one order of magnitude between thespecies, where species with high nitrogen concentrations had the highest ratio. Thisimplies that species with access to ample amounts of nitrogen can make more fungalcell walls in relation to plasma membrane surface area.