Integrating data, expert opinion and fuzzy logic in the development of an index of wetland condition

Abstract

Wetlands face an intensifying level of degradation, and management to protect their extent and character is paramount. To support wetland management in south-east Australia, we developed a wetland condition assessment tool for palustrine and lacustrine wetlands. Through extensive consultation with end users during its development, the tool, the Index of Wetland Condition (IWC), considers user needs and skills, as well as attempts to assess the complex nature of wetland systems and their inherent variability, both spatially and temporally. The IWC is structured as a hierarchical index with 13 indicators nested under six characteristics (subindices) that influence wetland function: wetland catchment, physical form, wetland soils, water properties, hydrology and biota. The contribution of each to the overall index (scored along a condition gradient) was estimated from quantitative biological and physicochemical data from 24 wetlands using a fuzzy cognitive map approach. The IWC development framework will be particularly useful in jurisdictions globally where reference condition information is limited or lacking for indicators, or where there are substantial practical constraints that limit the selection of indicators, such as management staff capability or capacity. Uptake of the IWC with wetland practitioners in south-east Australia has been substantial.