Macrolichen Communities of <em>Quercus garryana</em> in the Puget Trough and Columbia River Gorge Areas of Washington State

Abstract

We investigated macrolichen diversity on Quercus garryana at ten sites in the Puget Trough and Columbia River Gorge areas of Washington. The known ranges of some oak-associated species are expanded within Washington and occurrences of several species new to the state are reported. We identified 111 lichen taxa, 80 of which occurred at more than one site and three species, Fuscopannaria pulveracea, Placidium fingens and Collema quadrifidum , which are reported for the first time for Washington. We report four additional species, Bryoria furcellata, Dendriscocaulon intricatulum, Usnea cavernosa and Waynea californica , which are reported from oaks on two or fewer sites in Washington prior to this study. We compiled records from herbaria and other Washington oak lichen studies to evaluate the rarity of observed species and potentially rare species known from nearby locations. Using macrolichens we developed an Index of Ecological Continuity for oak habitats in Washington to help land managers assess the health of the lichen communities on oaks. We also recorded lichen species diversity and abundance in air quality monitoring plots at six of our sites in order to assess the threat level from increasing air pollution to oak lichens. We discuss the effects of management practices on lichen diversity and abundance at oak sites and suggest species of interest for future conservation efforts.