Using Expert Knowledge to Guide Transparent Mapping of Occupiable Threatened Species Habitat for Environmental Impact Assessment Purposes

Abstract

Consistent definition of environmental parameters to define occupiable threatened species habitat is important for quantifying the potential impact footprint as part of environmental impact assessments. Presently, occupiable habitats are often mapped based on subjective and varied understanding of what likely habitat is, leading to inconsistent environmental planning outcomes. Here, we outline a process for using expert elicitation to inform guidelines for defining and mapping occupiable habitat of two threatened Swainsona species and describe how findings can be incorporated into relevant environmental planning legislation. We use a structured modified Delphi IDEA expert elicitation protocol to seek expert opinion on environmental parameters for defining occupiable habitat and creating spatial polygons for mapping subpopulations. The elicitation process determined that experts considered Swainsona sericea persisted in lower condition vegetation than Swainsona recta, with both species absent from poorly drained soils. Variables related to site management history and foliage cover were uninformative. Experts also reached broad agreement on parameters for mapping occupiable habitat, including patch viability and buffer width. For threatened species where environmental parameters are difficult to define empirically, structured elicitation can help develop guidelines for mapping of occupiable habitat and improve the consistency of environmental impact assessment outcomes.