Environmental weeds in Australia and New Zealand: issues and approaches tomanagement

Environmental weeds are plants that invade natural ecosystems and are consi dered to be a serious threat to nature conservation. Australia and New Zeal and, where biota with a high degree of endemism have evolved, are particula rly susceptible to environmental weeds. Environmental weeds have been impli cated in the extinction of several indigenous plant species, and they also threaten ecosystem stability and functional complexity. Historically, empha sis has been placed on the chemical or manual 'control' of weed infestation s, often with little consideration of the long-term effectiveness or the ec ological consequences of such an approach. As the threat from environmental weeds is becoming more fully recognized, an integrated, strategic and ecol ogical approach to weed management is being recommended. In both countries, systems for screening new plants before allowing entry for cultivation hav e been developed. For already established plants, management is conducted w ithin a legislative and policy framework such as the Regional Pest Manageme nt Strategies that operate through the Biosecurity Act 1993 in New Zealand. Noxious weed legislation in Australia has historically focused on agricult ural weeds, but some Acts are (or have recently been) undergoing revision t o give greater emphasis to environmental weeds and the involvement of the c ommunity in weed management. Quarantine, legislation, research and on-groun d management are complemented by education programmes about the impact and control of environmental weeds. This paper provides an overview of the 'too l-kit' needed to manage environmental weeds in Australia and New Zealand, c omparing and contrasting the approaches taken in the two countries. It also provides a broad framework for the case studies that make up this special issue on the ecology and management of environmental weeds in both countrie s.