Modelling introduced predator and herbivore distribution in the Tanami Desert, Australia

This paper examines the pattern of introduced herbivore and predator distribution in the Tanami Desert and tests a series of propositions put forward by Stafford Smith and Morton [1990. A framework for the ecology of arid Australia. Journal of Arid Environments 18, 255–278]. regarding the functioning of arid Australian environments. These authors proposed that introduced herbivore and predator species would be largely restricted to and reliant on productive refugia. We collected occurrence data on introduced and naturalized predators and herbivores at 227 plots stratified by substrate and fire age class across a study area of 700×400 km. We also collected data from 16 repetitively sampled transects stratified by substrate and latitude over a 4 year period. Each of the predator species was associated with different landscape parameters and the proposition that predator diversity and abundance would be greatest in the productive habitats was not supported. There was support for the proposition that introduced feral herbivores would be concentrated in the productive habitats. Overall, the parameters reflecting the climatic gradient were the most important determinants of introduced species distribution in the Tanami Desert. Substrate-related variables or episodic variables such as fire age were of secondary importance at the scale considered. Furthermore, the variables that reflected episodic rainfall or periods of rainfall deviance did not form a significant component of the minimum adequate models for any of the species.