Influence of tree composition upon epiphytic macrolichens andbryophytes in old forests of Acadia National Park, Maine

摘要

To better understand associations between epiphytes and old forests, lichens andbryophytes that grow on tree bark were quantified in relatively undisturbed stands of AcadiaNational Park (ACAD). Four plots were dominated by hardwoods and eight by spruce. Toobtain data from upper boles, we climbed four maple trees per plot (eight plots) and fourspruce trees per plot (four of the eight plots). We found 85 macrolichen species and 62bryophyte taxa (60 species, two varieties). Eight macrolichens are newly documented fromACAD. At the state-level, Acadia NP plots were notably species-rich including 15 species notfound in 50 other plots in Maine surveyed using the USDA FS Forest Inventory and AnalysisProgram (FIA) lichen protocol. At the plot-level, the epiphyte flora of spruce-dominated plotsdiffered significantly from that of hardwood-dominated plots, although species richness wascomparable. At the tree-level, the epiphyte flora of maple trees was significantly influenced bytree composition within the surrounding stand. Mixed composition of tree species in thestand correlated with higher epiphyte diversity. Cyanolichens were more likely to occur onlarge hardwood trees in hardwood-dominated plots. Fruticose lichen occurrence wasinfluenced by interactions between tree size, plot and tree species. Using comprehensive treetally searches in combination with climbing of four maples per plot, we found that we missedan average of 15% of the macrolichen flora in the search area using only the two-hour timedsurvey required by the FIA protocol. This study serves as an important baseline for detectingfuture changes in the epiphyte flora of ACAD and further highlights the importance of maturemixed stands to epiphyte conservation in northern forests of eastern North America.