Understanding Long-Term Variations in an Elephant Piosphere Effect to Manage Impacts

M Landman; David S Schoeman; A J Hall-Martin; G I H Kerley

doi:10.1371/journal.pone.0045334

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Understanding Long-Term Variations in an Elephant Piosphere Effect to Manage Impacts

Journal article

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Understanding Long-Term Variations in an Elephant Piosphere Effect to Manage Impacts

M Landman, David S Schoeman, A J Hall-Martin and G I H Kerley

PLoS One, Vol.7(9), e45334

2012

DOI: https://doi.org/10.1371/journal.pone.0045334

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Abstract

elephant impact

biologicla diversity

biosphere

Surface water availability is a key driver of elephant impacts on biological diversity. Thus, understanding the spatio-temporal variations of these impacts in relation to water is critical to their management. However, elephant piosphere effects (i.e. the radial pattern of attenuating impact) are poorly described, with few long-term quantitative studies. Our understanding is further confounded by the complexity of systems with elephant (i.e. fenced, multiple water points, seasonal water availability, varying population densities) that likely limit the use of conceptual models to predict these impacts. Using 31 years of data on shrub structure in the succulent thickets of the Addo Elephant National Park, South Africa, we tested elephant effects at a single water point. Shrub structure showed a clear sigmoid response with distance from water, declining at both the upper and lower limits of sampling. Adjacent to water, this decline caused a roughly 300-m radial expansion of the grass-dominated habitats that replace shrub communities. Despite the clear relationship between shrub structure and ecological functioning in thicket, the extent of elephant effects varied between these features with distance from water. Moreover, these patterns co-varied with other confounding variables (e.g. the location of neighboring water points), which limits our ability to predict such effects in the absence of long-term data. We predict that elephant have the ability to cause severe transformation in succulent thicket habitats with abundant water supply and elevated elephant numbers. However, these piosphere effects are complex, suggesting that a more integrated understanding of elephant impacts on ecological heterogeneity may be required before water availability is used as a tool to manage impacts. We caution against the establishment of water points in novel succulent thicket habitats, and advocate a significant reduction in water provisioning at our study site, albeit with greater impacts at each water point.

Details

Title: Understanding Long-Term Variations in an Elephant Piosphere Effect to Manage Impacts
Authors: M Landman (Author) - Nelson Mandela Metropolitan University, South Africa
David S Schoeman (Author) - University of the Sunshine Coast - Faculty of Science, Health, Education and Engineering
A J Hall-Martin (Author) - Hall-Martin Consulting CC, South Africa
G I H Kerley (Author) - Nelson Mandela Metropolitan University, South Africa
Publication details: PLoS One, Vol.7(9), e45334
Publisher: Public Library of Science
Date published: 2012
DOI: 10.1371/journal.pone.0045334
ISSN: 1932-6203
Copyright note: Copyright © 2012 Landman et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This published version is reproduced in accordance with this policy.
Organisation Unit: School of Science and Engineering - Legacy; University of the Sunshine Coast, Queensland; School of Science, Technology and Engineering
Language: English
Record Identifier: 99450261702621
Output Type: Journal article