chapter  9
20 Pages

Remote Sensing of Tree–Grass Systems: The Eastern Australian Woodlands

ByTim Danaher, Peter Scarth, John Armston, Lisa Collett, Joanna Kitchen, Sam Gillingham

About 1.8 million square kilometers of Australia is, or was, covered by woodland vegetation communities, defined here as ecosystems, with widely spaced trees having an overstorey of vertically projected cover of photosynthetic foliage (FPC) of between 10% and 30%. The woodlands of Eastern Australia shown in Figure 9.1 are mostly located within the states of Queensland and New South Wales. This area includes tropical and subtropical savannas in the north and temperate and Mediterranean woodlands in the southern areas. The woodlands are located between the higher rainfall coastal areas to the east and arid areas to the west. The vegetation types within these woodland areas are quite diverse due to many factors including climate, geology, soils, presence or absence of fire, and land management practices (Lindenmayer et al., 2005). The predominant land use of these woodland areas is grazing of cattle and sheep. In all areas of northern Queensland where precipitation exceeds potential evaporation, vegetation growth is

CONTENTS

Introduction ......................................................................................................... 175 Technology That Matches the Scale of Problem in Space and Time ............ 178 Image Pre-Processing ......................................................................................... 178 Vegetation Cover Indices ................................................................................... 180

Field Calibration and Validation ............................................................. 181 FPC Model .................................................................................................. 183 Time Series Woody Extent and FPC Product ......................................... 183 Ground Cover ............................................................................................. 185

Woody Change .................................................................................................... 187 Discussion ............................................................................................................ 188 References ............................................................................................................. 190

water limited, and trees and grasses compete for rainfall. This has lead to widespread clearing of woody vegetation to increase pasture productivity, and significant areas of woodland have also been cleared for agriculture, particularly those on more fertile clay soils. Some ecosystems have been cleared to the extent that less than 10% of the pre-clearing area remains intact (Fensham et al., 2003). The clearing of woody vegetation has significant biodiversity and greenhouse gas emission implications (Henry et al., 2005).