Patterns of Rarity in Mosses of the Okanogan Highlands of Washington State: An Emerging Coarse Filter Approach to Rare Moss Conservation

Abstract

Increasing awareness of the importance of bryophytes in ecosystems has heightened efforts to conserve rare bryophyte species. Understanding the factors that influence rarity in bryophytes thus becomes valuable in developing conservation strategies. In order to decipher these patterns of rarity in mosses, 141 sites were sampled from a variable landscape in the Okanogan Highlands of Washington State. We split the 209 moss species found into three frequency groups (rare, frequent, and common) based on occurrence information and compared these groups based on different attributes. Comparison of these species to known lists of the area shows that the dry interior of Washington is grossly understudied. Moss distribution patterns on a local scale reflect world distribution patterns and may be dictated by habitat availability. Rare species occur on fewer habitats and occur in habitats that are unique or restricted on the landscape. Further, they occur more often in restricted mesohabitats (e.g., streams, cliffs, fens) than they do in unrestricted mesohabitats (forested or non-forested uplands). Mesohabitats, thus, emerge as an appropriate level for a coarse filter approach to prioritizing conservation efforts for rare mosses by land managers.