Achieving restoration targets and addressing completion criteria with remote sensing

Abstract

Alcoa of Australia has undertaken a progressive post-mining restoration program following bauxite mining in the jarrah forest of south-western Australia since operations began in 1963. Approximately 10,000 ha of restored forest is now of a suitable age for assessment and sign-off against agreed rehabilitation completion criteria. Remote sensing techniques have the potential to efficiently measure a range of attributes of post-mining restoration over areas of this size. We used airborne laser scanning and multispectral imagery from remotely piloted aircraft to estimate a range of forest canopy attributes. We also used these approaches to penetrate established tree canopies and measure understorey and the underlying terrain at very high resolution (e.g. 40 cm). We also used vegetation indices derived from Landsat satellite imagery for chronosequence assessment dating from the early 1970s. This paper describes investigations into the potential of these remote sensing techniques for assessment of older restoration and implementation within a process for sign-off with government. Field-based calibration is an essential component of these studies, and comparisons of on-ground measurement of vegetation structure and cover with remotely sensed indices are presented.