Plant invasion and extinction in a suburban coastal reserve

Abstract

In recent years there has been increasing concern with the problems of conservation of native biotic communities. While in most parts of Australia the area of land devoted to nature conservation has been increasing rapidly, little is known about such basic questions as the minimum area needed to maintain native communities in at least part of a reserve, or even the effects of intensive land use in surrounding areas on directly unmodified native vegetation. Yet, given the small areas contained in a large number of reserves devoted to nature conservation, these questions are of some importance. There is general acceptance of the view that the least desirable reserve for nature conservation in the long term is small in area with a large boundary/area ratio (Frankenburg, 1971). While surrounded by unmodified native communities such reserves remain viable. However, with increasing intensity of land use around their boundaries, they become more and more prone to a series of edge effects. These edge effects can include fertilizer drift, pesticide and herbicide drift, an increased susceptibility to firing, and increasing probabilities of introduction of exotic plants and animals. This and a subsequent article will document vegetation changes in the Sandringham Foreshore Reserve in the Melbourne Metropolitan Area, Victoria. The changes in the flora of the reserve will be traced from 1911 to 1971, covering the period in which the areas abutting on to the reserve developed from largely uncleared heath and scrub to upper middle class suburbia. The later article will describe and analyze the plant communities present in 1971, and will attempt to follow their development to that date. The value of this study lies in the insight it will give to the types of changes that can be expected in a reserve of unsuitable shape which has been subjected to increasingly intensive landuse both within and outside its boundaries. It is hoped that an understanding of the changes that have taken place in the extreme case will elucidate and allow the control of changes taking place in better situations.