Abstract
Biodiversity offsets are interventions that compensate for ecological losses caused by economic development, seeking ‘no net loss’ (NNL) of biodiversity overall. Calculating the ecological gains required to achieve NNL is non-trivial, with various methodologies available. To date, there has been no comparison among methodologies for a common case study. We use data on industrial impacts in Uzbekistan to provide such a comparison. We quantify losses from 40 years of gas extraction, using empirical data on vegetation impacts alongside estimates of disruption to mammals. In doing so, we implement a novel technique by estimating spatial ‘functional forms’ of disturbance to calculate biodiversity impacts. We then use a range of offset methodologies to calculate the gains required to achieve NNL. This allows a crude comparison of the potential biodiversity outcomes of ‘‘in kind’’ offsets (here, vegetation restoration) with ‘‘out of kind’’ offsets (protecting fauna from poaching). We demonstrate that different methods for calculating the required offset activities result in divergent outcomes for biodiversity (expressed in habitat condition x area, or ‘weighted area’), and different trajectories in biodiversity outcomes over time. An Australian method is currently being considered for adoption in Uzbekistan, but we show that it would require careful adjustments to achieve NNL there. These findings highlight that the method used to quantify losses and gains strongly influences the biodiversity outcomes of offsetting, implying that offsets generated using different methodologies are not transferable between jurisdictions. Further, conservation gains from out of kind offsets may outweigh those from strict in kind NNL interpretations. 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://
Highlights
Biodiversity offsets (‘offsets’) are a mechanism by which industry can compensate for unavoidable ecological losses associated with development (Madsen et al, 2011)
Various multipliers are applied to offset requirements, but here we focus on the basic habitat hectares metric (HH) metric itself
The various habitat-based methodologies result in a range of positive and negative net biodiversity outcomes evolving over the 40-year period, with none exactly compensating for biodiversity losses throughout (Fig. 4)
Summary
Biodiversity offsets (‘offsets’) are a mechanism by which industry can compensate for unavoidable ecological losses associated with development (Madsen et al, 2011). Offsets are implemented through both regulatory and voluntary schemes (Doswald et al, 2012). The essential objective of most offset policies is ‘no net loss’ (NNL) of biodiversity alongside economic development (BBOP, 2012; Bull et al, 2013a); accepting local losses at the sites of activity but compensating for these by producing equivalent biodiversity gains elsewhere. Address: Department of Life Sciences, Imperial College. Silwood Park Campus, Buckhurst Rd, Ascot, Berkshire SL5 7PY, UK.
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