Persistence and detection of weed locations in some New Zealand island weed programmes

摘要

As part of island weed eradication and control programmes managed by the New Zealand Department of Conservation, many weed locations have been monitored for over 15 years. Some species have been surprisingly persistent within the original detection site, and have remained intermittently active for many years, while others have died out within a few years.Regular grid searching and lucky finds have been the main method of finding new weed locations, but aerial surveillance and adaptive sampling have also resulted in new weed finds.Some weed locations were unexpected due to their remoteness from potential weed sources, and were probably spread by weed teams or wide ranging pests such as goats that have now been eradicated. Others were a surprise because they were within known survey sites or were near general work areas and well travelled roads.New weed species have been detected: these have either been dispersed from adjacent mainland sites by birds or wind, left by visitors, or were the relics of experimental pastoral farming and missed by earlier botanists.Improved GPS technology, mapping and database management have assisted in the management of island weed programmes by enabling teams to focus on search areas, to undertake self-checking of their search patterns and to understand the local environment.We are in the process of developing data loggers and aerial surveillance techniques to target eradication targets such as Psidium guajava L. and Olea europaea subsp. cuspidata (Wall ex G.Don) Cif