Using species niche models to inform strategic management of weeds in a changing climate

The expansion of the global area planted in fast-growing forest species seems likely as a means of offsetting carbon dioxide emissions and developing a sustainable bio-energy resource. Selecting appropriate sites for these plantations will require consideration of the effect of climate change on plantation growth and risks from abiotic and biotic factors. Buddleja davidii has been identified as a weed that has a major impact on plantation forest production in New Zealand. While it is at present restricted mainly to the North Island, a large proportion of the area identified for forest expansion is in eastern and southern regions of the South Island where the weed is presently relatively scarce. In this study we use a process-oriented climatic niche model (CLIMEX) to identify climatically suitable areas for B. davidii under current climate and future climate during the 2080s. This analysis indicates areas most at risk from invasion by B. davidii are in eastern and southern regions of the South Island. As B. davidii predominantly colonises disturbed areas, the likely increases in plantation forest area within this region can be expected to promote the spread of B. davidii. Strategies that could be implemented to manage B. davidii in this region are discussed. This study highlights the general utility of process-oriented niche models in identifying possible threats to planned primary production activities from invasive weed species. This type of knowledge is invaluable in planning and allocation of often scarce resources to most effectively control high impact weeds. Without the synoptic view of the invasion and the assets at risk, there is a strong potential for regional pest management to be parochial, and consequently less effective at all scales.