Goat browsing does not induce physical defences but reduces leaf size in Vachellia trees

Nzimande, Amanda; Mgqatsa, Nokubonga; Kraai, Unathi M; Tsvuura, Zivanai; Kraai, Manqhai

Title: Goat browsing does not induce physical defences but reduces leaf size in Vachellia trees
Creator: Nzimande, Amanda
Creator: Mgqatsa, Nokubonga
Creator: Kraai, Unathi M
Creator: Tsvuura, Zivanai
Creator: Kraai, Manqhai
Subject: To be catalogued
Date Issued: 2022
Date: 2022
Type: text
Type: article
Identifier: http://hdl.handle.net/10962/462624
Identifier: vital:76320
Identifier: xlink:href="https://doi.org/10.1016/j.actao.2022.103818"
Description: One aspect of plant-herbivore interactions in African savannas is the browsing impact of mammalian herbivores on plants, which may result in induced physical defences (spines) and changes in leaf morphology in trees experiencing intensive browsing. In these savannas, spinescence is considered to have evolved in response to herbivore pressure from large mammals. We assessed the impact of free-ranging domesticated goats on the spines and leaves of Vachellia karroo, V. nilotica and V. tortilis in Msinga, South Africa. We predicted that there would be fewer and smaller leaves, and longer spines occurring below compared to above 1.5 m for all tree species. We further predicted that the outer parts of the tree canopy would have smaller and fewer leaves, as well as more and longer spines compared to the inner part of the canopy. To determine the response of these trees to goat herbivory, 35 trees of each Vachellia species were selected, the number of leaves and spines found on two randomly selected branches below 1.5 m and one above 1.5 m were measured. We found that leaves were fewer and smaller below compared to above 1.5 m. Interestingly, we found the reduced leaf size to be equal to the size of spines below 1.5 m. We also found that V. karroo had more spines below 1.5 m compared to V. tortilis and V. nilotica. Along the branch segments, we found that spines were longer in the most accessible parts of the branch, the outer canopy. This study showed that browsing by goats, unlike wild herbivores, do not induce plant physical defences but rather limit available foliage. We also showed that physical defences (spine density) of Vachellia trees vary. This has implications for management and ecology of rangelands browsed by domestic mammals.
Format: computer
Format: online resource
Format: application/pdf
Format: 1 online resource (7 pages)
Format: pdf
Publisher: Elsevier
Language: English
Relation: Acta Oecologica
Relation: Nzimande, A., Mgqatsa, N., Kraai, U.M., Tsvuura, Z. and Kraai, M., 2022. Goat browsing does not induce physical defences but reduces leaf size in Vachellia trees. Acta Oecologica, 114, p.103818
Relation: Acta Oecologica volume 114 p. 103818 2022 1146-609X
Rights: Publisher
Rights: Use of this resource is governed by the terms and conditions of the Elsevier Terms and Conditions Statement (https://www.elsevier.com/legal/elsevier-website-terms-and-conditions)
Rights: Closed Access

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SDG 15. Life On Land

RU Department of Zoology and Entomology

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