Quantifying biomass fluctuations in Mitchell grassland, Queensland, using multi-temporal MODIS data

Abstract

Abstract: The Mitchell grassland in northern Australia covers more than 335,300 sq km of land. The sustainability of this unique ecosystem is the key to efficient use of grassland in related economic activities. In this regard, satellite images provide the most effective data source to monitor, especially when consider its huge coverage and homogeneous land cover. The amount of greenery of the grassland is directly related to fluctuations of the rainfall which has greater variations from year to year. The present study links greenness changes of Mitchell grass with rainfall fluctuations within rainy months. We utilized temporal MODIS images to study greenness changes in a selected area in eastern region of the Mitchell grassland. After evaluating the use of Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) in grassland and cropland studies, NDVI was used to extract greenness of the grassland. The mapping task was supported by field investigations already completed in the area and very high resolution image potions available in Google Image. Results clearly indicated a significant change in greenness, when the rainfall amount is changing within rainy months. The finding can be developed into a methodology that gives recommendations for the use of grassland, according to the productivity of the rainy season. Future research directions will include NDVI calculations for different dry months, and collecting field photo evidence under different rainfall conditions, to build a solid relationship between rainfall and sustainable use of the grassland.