How Wide, How Much? A Framework for Quantifying Economic and Ecological Trade-Offs of Altering Riparian Width on Agricultural Land

Creating and managing riparian buffer zones (RBZs) is regarded as a best-practice management strategy around the world for maintaining and improving the health of waterways. Agricultural land often utilises RBZs as highly productive pasture, exposing waterways to increased inputs of nutrients, pollutants and sediment, in addition to reducing carbon sequestration and habitat for native flora and fauna. The aim of this project was to develop a state-of-the-art dynamic geospatial tool that could quantify the ecological and economic impacts of switching from pasture to a revegetated riparian zone via planned restoration efforts. The tool was developed using the regional conditions of a south-east Australian catchment as a case study but is designed to be adaptable to other regions around the globe using equivalent model inputs. Outputs were determined using a number of methods, including an agricultural land suitability analysis to quantify primary produce, an estimation of carbon sequestration using historic vegetation datasets and GIS software analysis to determine spatial costings of revegetation and fencing. Gaps in knowledge around the impact of altering riparian width on biodiversity were addressed using habitat distribution models and the impact on water quality was simplified into conservative binary responses informed by a literature review. While similar models are designed for region-level analysis or are specific to small areas, this tool was able to provide property-specific data for almost 16,000 properties in a catchment area of over 130,000 km2. In this paper, we explore the potential for this visual tool to inform incremental revegetation plans and the selective harvesting of timber from the RBZ. The model provides an innovative framework for improved RBZ management and can be used to inform property-specific responses and guide discussion among stakeholders.