Diversity and succession of epiphytic macrolichen communities in low-elevation managed conifer forests in Western Oregon

We examined epiphytic macrolichen communities in Pseudotsuga menziesii (Dou glas-fir) forests across the western Oregon landscape for relationships to environmental gradients, stand age and structure, and commercial thinning. We used a retrospective. blocked design through the Coast and the western C ascade ranges of Oregon. Each of our 17 blocks consisted of a young. unthin ned stand (age 50-110 yr); an adjacent, thinned stand of equivalent age, an d an old-growth stand (age > 200 vr). We found 110 epiphytic macrolichen ta xa in the stands. Forage-providing alectorioid lichens and the nitrogen-fix ing cyanolichen Lobaria oregana associated strongly with old-growth stands and remnant old trees in younger stands (unthinned + thinned). Relative to unthinned stands, thinned stands had a slightly higher abundance of alector ioid lichens and a greater presence of Hypogymnia imshaugii, However, thinn ed stands hosted a lower landscape-level (gamma) diversity, lacking many sp ecies that Occurred infrequently in the unthinned stands. Patterns in the l ichen community composition correlated strongly with climatic gradients; th e greatest variation in composition was between the Coast and Cascade range s. The difference in communities between mountain ranges was greatest among stands 70-110 yr old, suggesting a difference in lichen successional dynam ics between the ranges.