Search this journal:     Advanced search
Original Research

Feeding choices and impacts of extralimital giraffe on two keystone tree species in the Kgalagadi National Park

Edmund February, Eleanor Shadwell, Storme Viljoen, Dawood Hattas

Koedoe; Vol 59, No 1 (2017), 10 pages. doi: 10.4102/koedoe.v59i1.1454

Submitted: 17 December 2016
Published:  29 May 2017

Abstract

In this article we determine the effect of an extralimital megaherbivore on the reproductive potential and vegetation structure of two keystone tree species in the Auob River in the south western Kalahari Desert of southern Africa. Using spoor and dung counts we establish the presence of giraffe in three predetermined density zones by walking 50 transects across the river in each zone. We also photographed six trees from each species in each zone and use these photographs to determine browse impact on reproductive potential, canopy volume as well as the percentage dieback on the extremities of the canopy. We then perform stable carbon and nitrogen isotope analysis on the leaves of the trees and compare these relative to the isotope ratios of giraffe dung to ascertain dietary preference. Crude protein was determined as a guide to nutritive value. Finally, we determine both chemical and physical defences for the two species. Our results show a significant negative impact of giraffe browse on tree canopies, no significant differences in recruitment and a noticeable decrease in flowers and pods at the giraffe browse height of 2 m – 5 m. No significant differences in crude protein or condensed tannins were found but significant differences in spinescence. Giraffe are not endemic to the Auob River and our study shows that the introduction of these animals is having a negative impact on the canopies of Vachellia haematoxylon. While there are, as yet, no significant impacts on reproductive potential we speculate that this will happen with time.

Conservation implications: Our study shows that giraffe are significantly impacting the canopies of two common tree species in the Auob River in the arid Kgalagadi Transfrontier Park. Without management intervention an increasing population of giraffe will result in substantial changes to the plant community vegetation structure of the river.


Full Text:  |  HTML  |  EPUB  |  XML  |  PDF (1MB)

Author affiliations

Edmund February, Department of Biological Sciences, University of Cape Town, South Africa
Eleanor Shadwell, Department of Biological Sciences, University of Cape Town, South Africa
Storme Viljoen, Department of Biological Sciences, University of Cape Town, South Africa
Dawood Hattas, Department of Biological Sciences, University of Cape Town, South Africa

Keywords

Rewilding; megaherbivore; reshape canopy structure; reproductive potential; physical and chemical defences; leaf nutrient status

Metrics

Total abstract views: 741
Total article views: 711

Cited-By

No related citations found

Comments on this article

Before posting your comment, please read our policy.
Post a Comment (Login required)


ISSN: 0075-6458 (print) | ISSN: 2071-0771 (online)

Connect on: Facebook, Twitter, Google+, LinkedIn and YouTube

Subscribe to our newsletter

All articles published in this journal are licensed under the Creative Commons Attribution 4.0 International (CC BY 4.0) license, unless otherwise stated.

Website design & content: ©2017 AOSIS (Pty) Ltd. All rights reserved. No unauthorised duplication allowed.

AOSIS Publishing | Empowering Africa through access to knowledge
Postnet Suite #110, Private Bag X19, Durbanville, South Africa, 7551Tel: 086 1000 381 Tel: +27 21 975 2602 Fax: 086 5004 974

publishing(AT)aosis.co.za replace (AT) with @

Please read the privacy statement.