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PLoS One. 2015 Jun 17;10(6):e0128340. doi: 10.1371/journal.pone.0128340. eCollection 2015.

Change in Mesoherbivore Browsing Is Mediated by Elephant and Hillslope Position.

Author information

1
School of Life Sciences, University of KwaZulu-Natal, Westville Campus, Private Bag, X54001, Durban, 4000, South Africa.
2
School of Life Sciences, University of KwaZulu-Natal, Westville Campus, Private Bag, X54001, Durban, 4000, South Africa; Centre for Ecological Sciences, Indian Institute of Science, Bangalore, 560012, India.
3
Resource Ecology Group, Wageningen University, Droevendaalsesteeg 3a, 6708 PB, Wageningen, The Netherlands.
4
School of Life Sciences, University of KwaZulu-Natal, Westville Campus, Private Bag, X54001, Durban, 4000, South Africa; Resource Ecology Group, Wageningen University, Droevendaalsesteeg 3a, 6708 PB, Wageningen, The Netherlands.
5
School of Life Sciences, University of KwaZulu-Natal, Westville Campus, Private Bag, X54001, Durban, 4000, South Africa; Department of Genetics, Evolution and Environment, University College, London, United Kingdom.

Abstract

Elephant are considered major drivers of ecosystems, but their effects within small-scale landscape features and on other herbivores still remain unclear. Elephant impact on vegetation has been widely studied in areas where elephant have been present for many years. We therefore examined the combined effect of short-term elephant presence (< 4 years) and hillslope position on tree species assemblages, resource availability, browsing intensity and soil properties. Short-term elephant presence did not affect woody species assemblages, but did affect height distribution, with greater sapling densities in elephant access areas. Overall tree and stem densities were also not affected by elephant. By contrast, slope position affected woody species assemblages, but not height distributions and densities. Variation in species assemblages was statistically best explained by levels of total cations, Zinc, sand and clay. Although elephant and mesoherbivore browsing intensities were unaffected by slope position, we found lower mesoherbivore browsing intensity on crests with high elephant browsing intensity. Thus, elephant appear to indirectly facilitate the survival of saplings, via the displacement of mesoherbivores, providing a window of opportunity for saplings to grow into taller trees. In the short-term, effects of elephant can be minor and in the opposite direction of expectation. In addition, such behavioural displacement promotes recruitment of saplings into larger height classes. The interaction between slope position and elephant effect found here is in contrast with other studies, and illustrates the importance of examining ecosystem complexity as a function of variation in species presence and topography. The absence of a direct effect of elephant on vegetation, but the presence of an effect on mesoherbivore browsing, is relevant for conservation areas especially where both herbivore groups are actively managed.

PMID:
26083248
PMCID:
PMC4471177
DOI:
10.1371/journal.pone.0128340
[Indexed for MEDLINE]
Free PMC Article

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