ABSTRACT
Rainfall varies from 4000 mm in the northeastern coastal zone to less than 250 mm in inland central Australia. The ecosystems of northern Australia should be regarded as a continuum of temperature and rainfall overlaying a wide variety of soils. Woodlands comprise almost half of semiarid tropical and subtropical regions in Australia. In the tussock grasslands of northern Australia, soil organic C is concentrated in the soil directly under tussock bases. Charcoal is a common component of Australian soils and is even found in rain forest soils. The Australian grazing lands carry numerous exotic pasture species, including grasses, medicago species, numerous acacias, siratro and stylo species. The initial soil organic C amounts and rates of decline are poorly known for most land use changes in most Australian climate regimes. Land clearing for grazing is still occurring in the Australian tropics, often resulting in substantial surface soil organic matter losses.
