Publication Date

2015

Document Type

Honors Thesis

Department

Biological Sciences

Keywords

Bazzania, Eastern hemlock, Hemlock woolly adelgid, Fiorinia externa., Ecophysiology, Salvage logging, Bazzania trilobata, Elongate hemlock scale

Abstract

Bazzania trilobata is a species of liverwort found throughout New England that often occurs in association with eastern hemlock (Tsuga canadensis). The impending loss of these trees due to attack by the invasive insects hemlock woolly adelgid (Adelges tsugae) and elongate hemlock scale (Fiorinia externa) raises concerns about the future of this ecosystem. Ecological changes already observed in this system include the replacement of eastern hemlock trees with black birch (Betula lenta) stands. These canopy changes are known to increase light exposure and raise temperatures, possibly putting sensitive, hemlock-associated understory species like B. trilobata at risk of decline. Similar environmental impacts may also be occurring in this system due to the forestry technique of salvage logging trees threatened by these exotic insects. I conducted a long-term transplant experiment with B. trilobata at two sites in western Massachusetts to assess the importance of eastern hemlock to this liverwort. I also executed a second transplant within a recently logged portion at one of the forest sites to consider the impacts of salvage logging. Results from the initial transplant suggest that B. trilobata performed best in areas with a higher abundance of eastern hemlock trees and consequently lower radiation. Preliminary findings from the salvage logging experiment suggest that the vigorous growth of successional herbs and shrubs may protect B. trilobata from excess bleaching.

Language

English

Comments

51 pages : color illustrations. Honors project-Smith College, 2015. Includes bibliographical references (pages 46-51)

Share

COinS