About Invasive Plant Management

Islands are global biodiversity hotspots. While accounting for less than 3% of the Earth’s land area, they are home to 20% of all bird, reptile and plant species. Moreover, a high proportion of species on islands are endemic, i.e. not found anywhere else in the world. This makes Pacific islands key to preserving global biodiversity.
Importance of island biodiversity 1
The interaction between native plant and animal components is essential to the maintenance of a healthy ecosystem
(Photo: Chris Thompson)

Loss of biodiversity on islands has a direct impact on people’s lives by reducing access to food, clean water, shelter and a source of income.  Many Pacific people remain heavily reliant on their unique biodiversity and ecosystems for their livelihoods and wellbeing. As well as having negative effects on island biodiversity, invasive plants can also reduce yields in cash crops or subsistence crops and there is likely to be additional hardship through the extra labour and costs required to manage the invasive species.

Some island communities and agencies are now taking a “ridge-to-reef” approach when managing the natural environment:  watershed or catchment-wide management ensures a healthy and intact native forest; streams with stable banks; minimal silt or other contaminants entering the water; healthy wetlands assisting in trapping silt and filtering contaminants; and a coastline well-vegetated in species which prevent coastal erosion.  Healthy native vegetation and stable ecosystems are essential to maintain the food-web inter-dependency among endemic and native birds, insects, invertebrates
and other fauna.

Importance of island biodiversity 2
Weaving mats from natural fibres.
(Photo: BirdLife International)

The threats to island biodiversity

Threats to island biodiversity can be caused by factors such as climate change and sea level rise, clearing of native vegetation for forestry, cropping or grazing and the harmful effects of invasive animal or plant species.

Pacific islands are particularly vulnerable to invasive species, because of their isolation and relatively recent human occupation. Pacific island species have not evolved to cope with the impacts of predators, herbivores, insect pests, highly competitive weeds, and diseases brought in from continental areas. Invasive species are responsible for the extinction of more island native species than any other cause. This is exacerbated by the fact that small island states often have limited human, material and financial resources available to tackle such threats.” (from Guidelines for Invasive Species Management in the Pacific. SPREP/SPC, 2009)