Seasonal growth dynamics in the lichen Lobaria pulmonaria

We monitored growth (as change in biomass) of Lobaria pulmonaria for approximately 3 years in western Oregon, re-weighing thalli eleven times over the 3 years. Thalli were grown as Pendant transplants in a Fraxinus latifolia forest. Most transplants survived for the full 3 years, with only 12 out of the 60 thalli missing by the end; another 9 were eliminated from the data set die to breakage. While growth rates were highly variable most thalli grew rapidly; mean biomass increases were 28%, 47%, and 69% over the first one, first two, and all 3 years, respectively. Growth rates were not correlated with starting sizes of transplants, which ranged from 0.18 to 0.56 g, but differences among individuals' growth rates were consistent over time. Growth rates were strongly seasonal. Thalli did not grow significantly during summer and early fall, which are dry seasons in the study area. Thalli grew throughout the wet seasons (November to June) and, in the year during which growth was measured most frequently, growth rates were maximal in spring, contrasting with our expectation that rapid growth would begin with the onset of autumn rains.