Rates of spread of an invading species: Mimosa pigra in northern Australia

W. M. Lonsdale
Journal of Ecology 81, 3, 513-521, 1993

Mimosa pigra, a woody weed, has invaded the wetlands of Northern Territory. This study examined the weed's expansion and tested the assumptions and predictions of Skellam's model for aerial spread, investigated the roles of wind, flood waters and buffalo, and compared the plant's rate of increase on local and geographical scales. Skellam' s model was found to be an inadequate descriptor of spread. There was a close correlation between the increase in the area colonised by the plant and the rainfall in the previous wet season. There was no evidence for the popular perception that feral buffalo grazing suppressed the weed, nor that the removal of grazing pressure caused an upsurge in the weed. Spread behaviour on a local scale was found to be applicable on a larger scale.