'RANGEWATCH': An NDVI based method of estimating forage biomass in northern Australia. A case study in the western Kimberly region of Western Australia

Abstract

An understanding of the current amount of total green biomass, total biomass and biomass growth rates is necessary for graziers to better manage pasture utilisation in the northern Australian grasslands. This project aims to assess the veracity (and challenges) of applying MODIS satellite-derived NDVI to calculating forage biomass in the complex landscapes of the northern tropical rangelands and to develop a web-based delivery platform providing forage estimates to producers ('Rangewatch'). The study site was located on a ~263 km² cattle station, located 250 km south east of Derby in Western Australia, on the Fitzroy River. All site locations were sampled during the 2011-12 and the 2012-13 growing seasons. In this study MODIS satellite NDVI image and climate data were used to produce estimates of pasture total green biomass (RMSE ± 825 kg DM/ha) and total biomass (green + dead) ( RMSE ± 1050 kg DM/ha) with a ~6.25 ha (250 m²) pixel resolution.