Thresholds of potential concern as benchmarks in the management of African savannahs

Gillson, Lindsey; Duffin, K.I.

doi:10.1098/rstb.2006.1988

Cited by 66 publications

(48 citation statements)

References 28 publications

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“…Large males are important gene contributors (Gillson & Duffin, 2007), implying that pre-ivory trade impacts of elephants on vegetation were not uniformly higher. Elephants are known under certain circumstances to cause local extinctions of other species (Chapter 3) and known to also have significant effects on structure of vegetation (Chapter 3).…”

Section: Chapter 12mentioning

confidence: 99%

Effects of Elephants on Ecosystems and Biodiversity

Kerley¹,

Landman²,

Kruger³

et al. 2008

Elephant Management

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ISBN 978 1 86814 479 2All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the express permission, in writing, of both the author and the publisher.Cover photograph by Donald Cook at stock.xchng Cover design, layout and design by Acumen Publishing Solutions, JohannesburgPrinted and bound by Creda Communications, Cape Town Foreword SOUTH AFRICA and its people are blessed with diverse and thriving wildlife. We are also a developing economy with a growing population. From these facts emerges the particular situation of having most of our protected areas surrounded by land that has been transformed, to a greater or lesser extent, by human development. Large mammals, such as elephants, no longer roam the entire landscape, and their populations are no longer completely governed by the laws of nature. Protecting elephants and the ecological systems in which they exist in a practical and sustainable way that balances the needs of humans, elephants and the environment is a challenge to which I am committed.This Assessment was undertaken to reduce the degree of scientific uncertainty associated with decisions that must be made very soon and in the medium-to-long term. It helps to evaluate the costs and benefits associated with each choice, both in economic and ecological terms, and clarifies the legal framework within which they must be made. Collectively the chapters in this report reveal the many successes our country's experts, in collaboration with their peers in neighbouring countries and abroad, have achieved in understanding elephants and their needs, in fields as diverse as veterinary science, ecology, animal behaviour, population and resource modelling.Importantly, the Assessment exposes important gaps in our understanding and thus outlines necessary future avenues of research. This Assessment represents a key milestone in an ongoing Elephant Research Programme.Science does not provide all the information required to resolve the difficult issues raised by the management of elephant in a changing and humandominated world. Many of the required decisions have a strong element of human values implicit in them. How do South Africans wish to treat the other species with which they share our land? Extensive consultation and careful consideration of the values expressed by a wide range of stakeholders is also an essential part of the process of managing elephant in a democratic country.I am grateful to the many experts and interested persons who invested their time, experience and intellect to deliver this Assessment. I look forward to their continued engagement on the issue of elephant management, which is of great interest to many. Marthinus van Schalkwyk Minister of Environmental Affairs and Tourism, 2008 ContentS LiSt oF FigureS LiSt oF boxeS About the AuthorS And ContributorS Brandon Anthony is an assistant professor at the Department of EnvironmentalScienc...

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Section: Chapter 12mentioning

confidence: 99%

Effects of Elephants on Ecosystems and Biodiversity

Kerley¹,

Landman²,

Kruger³

et al. 2008

Elephant Management

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“…Increasingly, protected area managers are setting targets for population size (Parrish et al 2003), or establishing population 'thresholds of concern' that trigger management actions (Biggs et al 2008). Niche models not only facilitate better prediction of where a species may occur both within and outside of protected areas, thereby enabling more efficient censusing and monitoring (van Wilgen et al 1998, Gillson andDuffin 2007), but also enhance predictions of where optimal habitats occur, thus enabling management to implement actions that facilitate higher recruitment and survival of species threatened with extirpation.…”

Section: Introductionmentioning

confidence: 99%

Using Maximum Entropy modeling to predict the potential distributions of large trees for conservation planning

et al. 2012

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Citation: Smith, A., B. Page, K. Duffy, and R. Slotow. 2012. Using Maximum Entropy modeling to predict the potential distributions of large trees for conservation planning. Ecosphere 3(6):56. http://dx.doi.org/10.1890/ES12-00053.1Abstract. Large trees, as keystone structures, are functionally important in savanna ecosystems, and low recruitment and slow growth makes their conservation important. Understanding factors influencing their distribution is essential for mitigation of excessive mortality, for example from management fires or large herbivores. We recorded the locations of large trees in Hluhluwe-Imfolozi Park (HiP) using GPS to record trees along 43 km of 10 m-wide transects. Maximum entropy modeling (MaxEnt) uses niche modeling to predict the distribution of a species from the probability of finding it within raster squares, based on environmental variables and recorded locations. MaxEnt is typically applied at a regional spatial scale, and here we assessed its usefulness when predicting the distribution of species at a small (local) scale. HiP has variable topography, heterogeneous soils, and a strong rainfall gradient, resulting in a wide variety of habitat types. We used locations of 179 Acacia nigrescens and 106 Sclerocarya birrea (large trees ! 5m), and raster environmental layers for: aspect, elevation, geology, annual rainfall, slope, soil and vegetation. A. nigrescens was largely restricted to the Imfolozi section, while S. birrea had a wider distribution across the reserve. Understanding the interaction of environmental variables dictating tree distribution may facilitate habitat restoration, and will assist planning decisions for persistence of large trees within reserves, including options to reduce fire frequency or herbivore impacts. Though the AUC (Area Under the Curve) values used to test model predictions were high for both species, the ground truthing test data showed that distribution for A. nigrescens was more accurate than that for S. birrea, highlighting the need for independent test data to assess model accuracy. We emphasize that MaxEnt can be used at finer spatial scales than those typically used for species occurrence, but models must be tested using spatially independent test data.

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“…To address these difficulties, ecosystem managers increasingly use a monitoring endpoint, known as thresholds of potential concern (TPC), to decide when management intervention is needed (Biggs & Rogers 2003). TPCs are a set of operational goals along a continuum of change in selected environmental indicators (Gillson & Duffin 2007). TPCs are being continually adjusted in response to the emergence of new ecological information or changing management goals.…”

Section: Operational Thresholds Of Potential Concernmentioning

confidence: 99%

“…TPCs are being continually adjusted in response to the emergence of new ecological information or changing management goals. They provide a conceptual tool that enables ecosystem managers to apply variability concepts in their management plans, by distinguishing normal 'background' variability from an important change or degradation (Gillson & Duffin 2007).…”

Section: Operational Thresholds Of Potential Concernmentioning

confidence: 99%

An ecosystem-based approach and management framework for the integrated evaluation of bivalve aquaculture impacts

Cranford¹,

Kamermans²,

Krause³

et al. 2012

Aquacult. Environ. Interact.

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An ecosystem-based approach to bivalve aquaculture management is a strategy for the integration of aquaculture within the wider ecosystem, including human aspects, in such a way that it promotes sustainable development, equity, and resilience of ecosystems. Given the linkage between social and ecological systems, marine regulators require an ecosystem-based decision framework that structures and integrates the relationships between these systems and facilitates communication of aquaculture-environment interactions and policy-related developments and decisions. The Drivers-Pressures-State Change-Impact-Response (DPSIR) management framework incorporates the connectivity between human and ecological issues and would permit available performance indicators to be identified and organized in a manner that facilitates different regulatory needs. Suitable performance indicators and modeling approaches, which are used to assess DPSIR framework components, are reviewed with a focus on the key environmental issues associated with bivalve farming. Indicator selection criteria are provided to facilitate constraining the number of indicators within the management framework. It is recommended that an ecosystem-based approach for bivalve aquaculture be based on a tiered indicator monitoring system that is structured on the principle that increased environmental risk requires increased monitoring effort. More than 1 threshold for each indicator would permit implementation of predetermined impact prevention and mitigation measures prior to reaching an unacceptable ecological state. We provide an example of a tiered monitoring program that would communicate knowledge to decision-makers on ecosystem State Change and Impact components of the DPSIR framework.KEY WORDS: Bivalve aquaculture management · Ecosystem-based approach · DPSIR framework · Indicators · Thresholds · Benthic effects · Pelagic effects · Social-ecological systems Resale or republication not permitted without written consent of the publisher

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Thresholds of potential concern as benchmarks in the management of African savannahs

Cited by 66 publications

References 28 publications

Effects of Elephants on Ecosystems and Biodiversity

Effects of Elephants on Ecosystems and Biodiversity

Using Maximum Entropy modeling to predict the potential distributions of large trees for conservation planning

An ecosystem-based approach and management framework for the integrated evaluation of bivalve aquaculture impacts

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