Kershaw, Melanie; (1997) Systematic approaches to setting conservation priorities using species' distribution data. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

The need to select priority areas for conservation action stems from the fact that throughout the world, human activity is increasingly resulting in the loss or irreversible alteration of natural ecosystems and their component species. Since there are not the resources to protect all species and communities and because diversity is not distributed equally, it has become necessary to select areas for conservation based on an assessment of the worthiness of a site compared with other sites or the countryside as a whole. The setting of such priorities for conservation is a difficult task and in the past has been highly subjective with no clear objective or targets. Recently there have been moves towards a more systematic approach to the selection of conservation areas, with the aim of representing the widest possible range of the biotic diversity as efficiently as possible. However, while this aim may be universal, its practical implementation and its implications are unclear. At a fundamental level there are three problems underlying attempts to make systematic selections of priority areas for conservation: (i) What is biodiversity and what are we trying to conserve. (ii) What surrogate measure can be used for overall diversity. and (iii) how should priority sites be selected using this information. These three problems are evaluated and possible solutions investigated for two extensive data sets of distribution data. The first is for Afrotropical antelopes and includes information on species richness, taxonomic diversity, richness of threatened species and degree of rarity, for 249 areas in Africa. The second data set consists of distribution data for birds, carnivores and ungulates and plants in KwaZulu Natal, South Africa. Using these data I discuss the different possible definitions of what constitutes biodiversity and investigate the consequences of using different components of biodiversity for selecting priority areas for conservation. These components include simple species richness, taxonomic diversity, threatened species, endemic species and 'rare' species. The second problem associated with setting priorities for conservation is that since we do not know how many species exist or how they are distributed it is necessary to have some sort of surrogate measure that can be used to evaluate the importance of areas for a wide range of biotic diversity. Different potential surrogate measures, including indicator groups, higher taxon richness, endemic species and habitat representativeness are evaluated in terms of their ability to represent a range of diversity across a variety of taxa. Finally, once the diversity value of different sites has been determined it is necessary to select a network of priority areas to represent the diversity. This requires some sort of site selection method. Simple scoring approaches where the top ranking sites for particular diversity criteria are compared to more sophisticated techniques using iterative algorithms that take account of complementarity.

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