Managing invasive weeds under climate change: considering the current and potential future distribution of Buddleja davidii

P>Buddleja davidii is both a prized garden ornamental and an invasive shrub that rapidly colonises disturbed ground. Originally from China, B. davidii has been widely distributed by horticulturalists and has subsequently invaded much of Europe and New Zealand, and to a lesser degree the Americas and Australia. The present and future climate suitability for B. davidii was assessed using a process-oriented climate suitability model. There appears to be a considerable scope for further invasion, with the most suitable areas occurring adjacent to existing naturalised populations in the north-eastern United States, north-eastern Europe, south-eastern Australia and south-eastern New Zealand. Under future climates, the potential distribution and climate suitability for B. davidii increases most noticeably in the northern United States and southern Canada, northern and eastern Europe, and to a lesser extent in the south-western part of the South Island of New Zealand. Elsewhere, there are projected poleward range shifts (South America) or range contractions out of subtropical areas (Africa and Australia). Climate-based potential distribution models can help adapt weed management programmes to expected climate changes by: (i) classifying areas for the different types of weed management, (ii) supporting strategic control initiatives to prevent the spread of a weed, (iii) informing the reallocation of resources away from controlling a weed where climate suitability is expected to diminish in the future and (iv) identifying opportunities for relatively inexpensive preventative management to be applied to minimise future weed impacts.