Conceptualising and managing trade-offs in sustainability assessment

One of the defining characteristics of sustainability assessment as a form of impact assessment is that it provides a forum for the explicit consideration of the trade-offs that are inherent in complex decision-making processes. Few sustainability assessments have achieved this goal though, and none has considered trade-offs in a holistic fashion throughout the process. Recent contributions such as the Gibson trade-off rules have significantly progressed thinking in this area by suggesting appropriate acceptability criteria for evaluating substantive trade-offs arising from proposed development, as well as process rules for how evaluations of acceptability should occur. However, there has been negligible uptake of these rules in practice. Overall, we argue that there is inadequate consideration of trade-offs, both process and substantive, throughout the sustainability assessment process, and insufficient considerations of how process decisions and compromises influence substantive outcomes. This paper presents a framework for understanding and managing both process and substantive trade-offs within each step of a typical sustainability assessment process. The framework draws together previously published literature and offers case studies that illustrate aspects of the practical application of the framework. The framing and design of sustainability assessment are vitally important, as process compromises or trade-offs can have substantive consequences in terms of sustainability outcomes delivered, with the choice of alternatives considered being a particularly significant determinant of substantive outcomes. The demarcation of acceptable from unacceptable impacts is a key aspect of managing trade-offs. Offsets can be considered as a form of trade-off within a category of sustainability that are utilised to enhance preferred alternatives once conditions of impact acceptability have been met. In this way they may enable net gains to be delivered; another imperative for progress to sustainability. Understanding the nature and implications of trade-offs within sustainability assessment is essential to improving practice

Climatic fluctuations shape the phylogeography of a mesic direct-developing frog from the south-western Australian biodiversity hotspot

To assess phylogeographic pattern throughout the range of Metacrinia nichollsi in order to develop specific biogeographical hypotheses for the wet forests of south-western Australia. This was carried out by contrasting a direct-developing frog species, M. nichollsi, that breeds independently of free surface water with conventional, aquatic breeders and highly specialized direct developers. Wet forests of the south-western Australian biodiversity hotspot - an area of high species richness and endemism for myobatrachid frogs and many other faunal groups. We compiled an extensive phylogeographic data set from field-collected samples based on mitochondrial ND2 sequences. Phylogenetic analyses combined with estimates of divergence times were used to build a model of major biogeographical events affecting the species. Phylogeographic analyses were used to provide insights into smaller-scale processes acting within each major lineage. Phylogenetic analysis recovered three major lineages, with divergence dates coincident with late Miocene-early Pliocene arid cycles. One lineage was confined to geographically isolated populations in the Stirling Ranges (Stirling Ranges Lineage, SRL). The continuous range of M. nichollsi was split into two: the Main Range Lineage (MRL) and the Southern Coastal Lineage (SCL). The SCL displays a strong drainage-based population structure, whereas the MRL displays a strong signature of recent expansion, suggesting that these two lineages have had very different biogeographical histories. Late Miocene-Pliocene aridity appears to have isolated populations in the Stirling Ranges and resulted in the formation of two additional lineages on a north-south gradient that are independent of southward-flowing drainage systems. Our results demonstrate that climatic fluctuations are likely to have generated fine-scale phylogeographic structure within M. nichollsi and that catchment regions are important refugia during arid cycles

Re-evaluating sustainability assessment: Aligning the vision and the practice

Sustainable Development is the core goal of the expanding field of Sustainability Assessment (SA). However, we find that three key areas of debate in relation to SA practice in England and Western Australia can be classified as policy controversies. Through literature review and analysis of documentary evidence we consider the problem of reductionism (breaking down complex processes to simple terms or component parts) as opposed to holism (considering systems as wholes); the issue of contested understandings of the meaning of sustainability (and of the purpose of SA); and the definition of ‘inter-generational’ in the context of sustainable development and how this is reflected in the timescales considered in SA. We argue that SA practice is based on particular framings of the policy controversies and that the critical role of SA in facilitating deliberation over these controversies needs to be recognised if there is to be a move towards a new deliberative sustainability discourse which can accommodate these different framings