INTERACTIONS OF NORTHWEST FOREST CANOPIES AND ARBOREAL MAMMALS

The interactions among Northwest forest canopies and the mammals that inhabit them have been poorly studied. My purpose was to identify inte ractions among arboreal mammals and canopies that have implications fo r managers seeking to conserve biodiversity in the Pacific Northwest. I constructed a comprehensive, but parsimonious list of canopy attribu tes that could be biologically important. I compiled a list of mammals that routinely enter the canopy and ranked them relative to arboreali ty. I identified which attributes might be important to each species a nd how the attributes might contribute to maintaining arboreal rodent communities. Forest canopies have 26 categories of attributes of 5 maj or types: context, seral stage, community type, canopy dimensions, and tree species character, At least 12 species of mammals (excluding bat s) use forest canopies, but only 7 should be considered truly arboreal . Ail but one of the arboreal rodents are Limited zoogeographically, o r in local distribution. because of needs for specific habitat element s. Only one species, the red tree vole, is totally arboreal; thus, the composition and structure of the arboreal rodent community is conditi oned by both canopy and noncanopy features of the forest. Of the canop y attributes, diversity of tree species and abundance of nontree organ isms, including lichens, mosses, and rot inducing fungi, seem especial ly important to arboreal rodents, Diversity of tree species provides a variety of food (foliage, seed, fruit, nuts, and truffles and mushroo ms of fungi symbiotic with the trees). Rot-inducing (and pathogenic) f ungi provide cavities for leaf-lichen-moss nests and platforms for lic hen-moss-twig nests. Lichens also serve as food.