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 interactions among arboreal mammals and canopies that have implications for managers seeking to conserve biodiversity in the Pacific Northwest. I constructed a comprehensive, but parsimonious list of canopy attributes that could be biologically important. I compiled a list of mammals that routinely enter the canopy and ranked them relative to arboreality. I identified which attributes might be important to each species and how the attributes might contribute to maintaining arboreal rodent communities. Forest canopies have 26 categories of attributes of 5 major types: context, seral stage, community type, canopy dimensions, and tree species character, At least 12 species of mammals (excluding bats) use forest canopies, but only 7 should be considered truly arboreal. Ail but one of the arboreal rodents are Limited zoogeographically, or in local distribution. because of needs for specific habitat elements. Only one species, the red tree vole, is totally arboreal; thus, the composition and structure of the arboreal rodent community is conditioned by both canopy and noncanopy features of the forest. Of the canopy attributes, diversity of tree species and abundance of nontree organisms, including lichens, mosses, and rot inducing fungi, seem especially important to arboreal rodents, Diversity of tree species provides a variety of food (foliage, seed, fruit, nuts, and truffles and mushrooms of fungi symbiotic with the trees). Rot-inducing (and pathogenic) fungi provide cavities for leaf-lichen-moss nests and platforms for lichen-moss-twig nests. Lichens also serve as food.