Invasive Species Compendium

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Abstract Full Text

Breaking Bad - 10 years into a projected 30 year weed eradication program on world heritage listed Lord Howe Island.

Abstract

The Lord Howe Island Weed Eradication Program is possibly one of the most ambitious island weed eradication programs on an inhabited island, in the South Pacific - if not globally - given the density, distribution and diversity of weed populations that were present on the island at the program's commencement. The program aims to search all weed management blocks, at two year intervals to continue to deplete target weeds. Novel techniques to survey and eradicate weeds on inaccessible terrain have been employed. Since program inception in 2004, in the first 10 year period, the number of weeds, of up to 25 species has reduced by 80% (all life stages) and matures by 90% comparing first and last, measured treatments across 1164 hectares. The top two weed species removed include cherry guava (Psidium cattleyanum Sabine var. cattleyanum) and ground asparagus (Asparagus aethiopicus L.). Six weeds have been declared eradicated, however they were initially limited in occurrence. Over two million individual weeds have been removed over the ten year period at a cost of AUD $6.4 million. For the broader dispersed species the program is in the 'active' eradication phase (Panetta 2007) with mature weeds still being removed, albeit at a significantly reduced rate than at commencement. The strong downward trend in weeds removed per weed block suggests that the program will reach the 'containment and monitoring' phase for widespread species within the next decade; given sustained investment and technical solutions for weeds on cliff lines. However, the duration and lead in time makes the program vulnerable to eradication fatigue. Eradication is considered the optimum investment if the goal is to provide long term protection to Lord Howe Island World Heritage listed ecosystems from weed threat.