The status and distribution of non-native plants on the gazetted and territorial islands off the north coast of Western Australia

Non-native plants pose a substantial threat to island ecosystems in Australia and worldwide. A better understanding of weed distributions is necessary to more effectively manage natural resources on islands. To address this need for Western Australian islands, we created a database of all available records of non-native plants on these islands. Here we report on records from all islands located along the coast of the Pilbara and Kimberley regions in the northern half of Western Australia as well as territorial islands including Christmas Island, the Cocos Islands and the islands of Ashmore Reef. From 2936 individual records, a total of 403 non-native plant species were recorded on 100 Pilbara islands, 51 Kimberley islands and 21 territorial islands. Some of the species are known to be serious environmental weeds. We provide some information on the invasive characteristics and management of 14 environmental weeds for oceanic islands and 12 environmental weeds for continental islands. Developing management plans to address these species, as well as surveying islands adjacent to known infestations, should be a conservation priority for north coast islands. Improved biosecurity procedures and enforcement could prevent the establishment of new island weed populations and reduce future costs associated with the management of active infestations