Dissertation Research: Dispersal of moss spores by birds: elucidating the mechanisms of behaviorally enhanced bryophyte dispersal networks

Portland State University, Portland OR

Investigators

Abstract

Individual animals and plants often move from their places of birth to new locations, where they live out their lives. This movement, known as "dispersal", is important in ecology because it largely determines where species are found, which species come in contact with each other, and the services they can then provide to nature and to humans. Sometimes, plants depend on animals for dispersal. Many trees and shrubs, for example, rely on birds to eat their fruits and defecate their seeds somewhere else. Mosses may also rely on birds for dispersal of spores, which are like seeds, but practically nothing is known about it. Researchers will study how often spores are found on the feathers of birds and whether the spores are actually dispersed by the birds. Mosses play an important role in ecosystems by contributing to nutrient cycling, maintaining water, and providing nesting material and places to forage for many forest animals. By understanding the relationship between moss dispersal and bird behavior, managers and policy makers will have a more complete picture of how land use decisions influence the use and conservation of natural resources. Dispersal is a key process shaping ecological communities over time. Behaviorally-mediated dispersal via an association with an animal vector can greatly increase the chances of arriving in a favorable locale. While the impact of avian dispersal of seed plants has been widely studied and is known to impact dispersal outcomes, avian dispersal of bryophyte spores has received little attention. Preliminary work has shown that bryophyte spores are present on a wide variety of bird species, and that these spores are viable. In addition, there is evidence for species-specific relationships between birds and bryophytes. Building on this work, this project has two aims: 1) to determine how behaviorally-directed dispersal by birds differs from bulk spore flow via wind, and 2) to determine the topical retention time of spores on birds. Results from the second aim will be incorporated into a model of flight distance times to address the likelihood of long distance spore dispersal by birds. Together, these aims will enhance understanding of bryophyte dispersal ecology and will provide a comparative model that can be used to test theories developed in tracheophytes.