Wigley, BJ, Coetsee, C, Augustine, DJ et al. (3 more authors) (2019) A thorny issue: Woody plant defence and growth in an East African savanna. Journal of Ecology, 107 (4). pp. 1839-1851. ISSN 0022-0477
Abstract
Recent work suggests that savanna woody plant species utilise two different strategies based on their defences against herbivory; a low nutrient/high chemical defence strategy and a nutrition paired with mostly architectural defences strategy. The concept that chemical and structural defences can augment each other and do not necessarily trade-off has emanated from this work. In this study, we examine woody plant defence strategies, how these respond to herbivore removal and how they affect plant growth in an East African savanna. At three paired long-term exclosure sites with high browser and mixed-feeder densities at Mpala Ranch, Kenya, we investigated: (a) whether defences employed by the dominant fine- and broad-leaved woody savanna species form defence strategies and if these align with previously proposed strategies, (b) how nine key plant defence traits respond to herbivore removal and (c) how effective the different defence strategies are at protecting against intense herbivory (by measuring plant growth with and without herbivores present). We identified three defence strategies. We found a group (a) with high N, short spines and high N-free secondary metabolites, a group (b) with high N, long spines and low N-free secondary metabolites and a group (c) with moderate N, no spines and low N-free secondary metabolites (most likely defended by unmeasured chemical defences). Structural defences (spine length, branching) were generally found to be induced by herbivory, leaf available N increased or did not respond, and N-free secondary metabolites decreased or did not respond to herbivory. Species with long spines combined with increased “caginess” (dense canopy architecture arising from complex arrangement of numerous woody and spiny axis categories) of branches, maintained the highest growth under intense browsing, compared to species with short spines and high N-free secondary metabolites and species with no spines and low N-free secondary metabolites. Synthesis. At our study site, structural traits (i.e. spines, increased caginess) were the most inducible and effective defences against intense mammalian herbivory. We propose that high levels of variability in the way that nutrient and defence traits combine may contribute to the coexistence of closely related species comprising savanna woody communities.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2019 The Authors. Journal of Ecology © 2019 British Ecological Society. This is the peer reviewed version of the following article: Wigley, BJ, Coetsee, C, Augustine, DJ et al. (3 more authors) (2019) A thorny issue: Woody plant defence and growth in an East African savanna. Journal of Ecology, 107 (4). pp. 1839-1851, which has been published in final form at https://doi.org/10.1111/1365-2745.13140. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. |
Keywords: | herbivore exclosures, induced defences, mammal browsers, N-free secondary metabolites, plantdefencestrategies,plant–herbivoreinteractions,structuraldefences |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Biological Sciences (Leeds) > School of Biology (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 13 Mar 2019 12:22 |
Last Modified: | 25 Jan 2020 01:39 |
Status: | Published |
Publisher: | Wiley |
Identification Number: | 10.1111/1365-2745.13140 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:143586 |