Graduation Term

2015

Degree Name

Master of Science (MS)

Department

School of Biological Sciences

Committee Chair

Roger C. Anderson

Abstract

Alliaria petiolata, an herbaceous plant, has aggressively invaded North American woodlands. It has been extensively studied to understand why it is a successful invader, but certain aspects of its biology have been understudied such as seed dispersal distances and long distance dispersal mechanisms (LDDM). My thesis experimentally measured A. petiolata seed dispersal distances and determined if epizoochory (external animal transport) is a LDDM. To measure dispersal distances, seed traps were placed around three A. petiolata seed point sources to capture dispersed seeds at increasing distances away from the point sources. Eight mathematical functions that describe dispersal distances were fitted to seed counts in traps via maximum likelihood. The lognormal and 2Dt functions were selected for analyses and both predicted that seed density rapidly declined as distance increased with mean dispersal distances of 0.56 and 0.52m and 95% of seeds dispersed within 1.22 and 1.14m, respectively.

To determine if epizoochory is a LDDM, experimental blocks were placed around seven dense A. petiolata patches in summers 2013-2014. Each block contained a mammal inclusion treatment (MIT), which increased small mammal activity over a germination

tray with potting soil, and a control, which excluded mammal activity. Seeds dispersed into trays were germinated and counted. The increased mammal activity in the MIT resulted in significantly more A. petiolata seedlings than the control.

Laboratory studies determined if A. petiolata seeds can attach and be retained by raccoon (Procyon lotor) and white-tailed deer (Odocoileus virginianus) fur, common woodland mammals. A small proportion (3-26%) of seeds attached to and were retained within raccoon and deer fur. Attachment and retention significantly increased if either the seed or fur was wet (57-98%). These results are the first to experimentally determine that epizoochory is a seed dispersal mechanism of A. petiolata with raccoon and deer as likely dispersal agents.

Access Type

Thesis-Open Access

DOI

http://doi.org/10.30707/ETD2015.Loebach.C

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