A Distributional Study of the Epiphytic Plants of the Olympic Peninsula, Washington

Abstract

In the generally mesophytic conditions of New York state were found on 63 hosts, chiefly native trees and shrubs, a total of 111 epiphyte species: 37 lichens, 3 algae, 25 liverworts, 43 mosses and 3 ferns (Brown, 1948). For comparative data from a region of higher rainfall investigation of epiphytes was continued, duritng the summer of 1950, on the Olympic Peninsula in western Washington, where, in some places, the rainfall may reach 144 inches annually. Epiphytes were collected at 20 sites within 15 general areas of the peninsula, differing in proximity to coast, in relationship to mountains and to prevailing winds, in altitude, in general habitat and in potential hosts. On 43 species of conifers, hardwoods and shrubs were found altogether 195 epiphyte species, varieties and forms: 105 lichens, 36 liverworts, 48 mosses, 1 lycopsid and 5 ferns. The total body of information obtained includes the identity of host species present and examined, identity of epiphytes found on each host and location of epiphyte on host at each of the collecting stations. Out of this complex mass of data there should be extractible some general information about the factors that control epiphyte distribution, at least within the Olympic Peninsula. A priori, three main types of variable would seem likely to be relevant: 1) biotic-the potential hosts and competitors present at a given site; 2) climatic-perhaps chiefly the annual cycle, and range of variation within shorter intervals, of moisture and temperature at the epiphyte's surface; 3) historic.-relating to the opportunity each potential epiphyte has had to arrive, and become established, at a given site. Considering the number of possible factors and their likely interrelationships it is scarcely to be expected that analysis of the data would be a simple matter. Certain initial steps, with, of course, most of the primary data will be reported here. Further study is in progress.