Landscape Ecology

, Volume 30, Issue 10, pp 2161–2174 | Cite as

Termite mounds mitigate against 50 years of herbivore-induced reduction of functional diversity of savanna woody plants

  • Grant S. Joseph
  • Milton Makumbe
  • Colleen L. Seymour
  • Graeme S. Cumming
  • Zacheus Mahlangu
  • David H. M. Cumming
Research Article

Abstract

Context

Spatially heterogeneous habitats often promote woody plant species and functional diversity (FD). Ungulate herbivory can have the opposite effect. Across the globe, the type and intensity of herbivory is changing, as domestic livestock replace wild ungulates, which are increasingly confined to protected areas. Despite recognition of the importance of FD for ecosystem functioning, the interactive effect of soil-related fine-scale heterogeneity and larger-scale ungulate herbivory on woody plant FD is little-known.

Objectives

In miombo woodland of Zimbabwe, we investigated (1) how bottom-up fine-scale heterogeneity created by Macrotermes termitaria interacts with top-down effects of herbivore foraging-guilds on woody plant FD; and (2) whether browsing combined with grazing impacts FD more than grazing alone.

Methods

The three different herbivore treatments (grazing, combined browsing-and-grazing, and exclusion) had been maintained for 50 years. We surveyed 10 termite mound-matrix plots within three sites per treatment. We assessed woody plant traits and FD across treatments (herbivore feeding-guild) and position (mound or woodland-matrix), and interactive effects between these.

Results

Woody plant FD was greater on mounds, and lowest overall with browsing-and-grazing. Specific traits were associated with position (e.g. palatability was greater for mounds), and treatment (e.g. spinescence increased with grazing).

Conclusions

Long-term enclosure of ungulate herbivores (browsing-and-grazing, and grazing alone) decreased woody FD, but this was mitigated by termitaria. The novel finding is that at regional scales, mounds can enhance woody plant FD despite the impacts of herbivory. At broader scales encompassing the miombo system, potential exists for mounds to stabilise woody plant FD from livestock-induced impacts.

Keywords

Bottom-up versus top-down effects Functional divergence Functional evenness Functional richness Spatial heterogeneity Termitaria 

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Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  • Grant S. Joseph
    • 1
  • Milton Makumbe
    • 3
  • Colleen L. Seymour
    • 1
    • 2
  • Graeme S. Cumming
    • 1
    • 4
  • Zacheus Mahlangu
    • 3
  • David H. M. Cumming
    • 1
    • 3
  1. 1.Percy FitzPatrick Institute of African Ornithology, DST/NRF Centre of Excellence, Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
  2. 2.South African National Biodiversity InstituteKirstenbosch Research CentreCape TownSouth Africa
  3. 3.Tropical Resource Ecology Programme, Department of Biological SciencesUniversity of ZimbabweHarareZimbabwe
  4. 4.ARC Centre of Excellence for Coral Reef StudiesJames Cook UniversityTownsvilleAustralia

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