Three groups of students designed and executed lichen transplant studies in an old-growth Pseudotsuga-Tsuga forest at the Wind River Canopy Crane in the southern Washington. Each team focused on a particular question or hypothesis of their own choosing. This paper does not address their specific hypotheses, but rather summarizes differences in growth with respect to height in the canopy. Four species of macrolichens grew much faster in middle to upper canopy positions than in the lower half of the canopy, based on 300 transplants. This held true for species that peak in the upper canopy (Letharia vulpina and Usnea filipendula) as well as those with peak abundance in mid canopy (Lobaria oregana and Lobaria pulmonaria). Lichens lost weight or died below the light transition zone. These results can be mimicked by a simple model of lichen net photosynthesis (Ps) as a function of cumulative leaf area (CLA) leaf area above a certain level in the canopy. CLA influences both light and moisture regimes. We hypothesize that gross Ps, integrated over a year, increases to a plateau with canopy height, while respiration decreases linearly with canopy height. The dependence of CLA on height in the canopy will vary a lot from forest to forest and is likely to be an extremely important variable in controlling the epiphyte profile. The paradox is that some species (Lobaria oregana and Lobaria pulmonaria) grow faster at higher levels in the canopy than in their stratum of peak abundance. Possible resolutions of the paradox invoke competition, uncommon extreme environmental events (such as extreme high or low temperatures), and dispersal limitations.

Key words: canopy structure, Letharia, lichens, Lobaria, transplant experiment, Usnea