Simplified structure or fewer arthropods to eat?: disentangling the impacts of an invasive plant on breeding bird diversity in agricultural hedgerows
Edmonds, Madeline (author)
Joy, Ruth (thesis advisor)
British Columbia Institute of Technology School of Construction and the Environment (Degree granting institution)
Simon Fraser University Faculty of Environment (Degree granting institution)
(Degree granting institution)
© Madeline Edmonds, 2020. All rights reserved. No part of this work covered by the copyright heron may be reproduced or used in any form or by any means – graphics, electronic, or mechanical including photocopying, taping, or information storage and retrieval systems – without written permission of the author.
British Columbia Institute of Technology
In agricultural landscapes, hedgerows provide critical habitat for songbirds. Himalayan Blackberry (Rubus armeniacus; HBB) is a widespread invasive species in the Pacific Northwest that has been linked to lower breeding songbird diversity. My study explored two possible explanatory mechanisms: educed structural complexity and lower arthropod abundance as a food source. I conducted avian point counts in 51 hedgerow segments at two locations in the Lower Mainland of British Columbia. In these segments, I quantified vegetation structure using a Foliage Height Diversity (FHD) metric derived from LiDAR data. I sampled arthropod abundance on the foliage of woody understory vegetation. I used multiple regression to identify best fit generalized linear models. Songbird diversity decreased with HBB % cover and increased with FHD. However, arthropod abundance was unrelated to bird metrics, and similar between HBB and other native shrubs. This suggests that hedgerows should be managed to control HBB and maximize vegetation structure.
Ecological Restoration Program
Master of Science