Water, Light and Temperature Relations of the Epiphytic Lichens Parmelia olivacea and Parmeliopsis ambigua in Northern Swedish Lapland

P. Olivacea had photosynthetic rates twice as high as P. ambigua at temperatures likely to be experienced in the field from late spring to late autumn. Optimum photosynthetic rates were obtained at 20 o C and 15 o C, light saturation at 500 and 300 μmol m −2 S −1 and water saturation level for photosynthesis at 200 and 100% of dry weight in P. olivacea and P. ambigua, respectively