Combining climate models and risk assessment tools to evaluate the invasive potential of intentional plant introductions: a case study of Moringa oleifera in New Zealand

An increasing number of alien plants are escaping cultivation and becoming invasive worldwide, with devastating ecological and economic consequences. As a result, it is crucial to better assess the risks associated with intentional plant introductions before widespread cultivation, even when these plants offer potential economic benefits. In this study, we explore the use of climate suitability and weed risk assessment (WRA) tools to evaluate the invasiveness risk of Moringa oleifera (moringa) in New Zealand. Moringa is valued globally for its nutritional content and potential health benefits, making it an attractive candidate for cultivation outside its native range. Although not yet widely grown in New Zealand, the rising demand for moringa products could lead to increased cultivation and distribution. Therefore, it is essential to ensure that this crop’s expansion is both environmentally and socially responsible, preventing it from becoming invasive and threatening native species. Climate suitability analysis identified Northland and surrounding areas as potential sites for moringa growth under current climate. The Composite Match Index, which measures the climatic similarity between current global distribution sites and potential locations in New Zealand, showed an increase from 0.52 in 2030 to 0.55 in 2070 under medium climate change scenarios, suggesting that climate change will facilitate the plant’s expansion. The invasive risk assessment model classified moringa as a low-risk species for invasiveness in New Zealand, with a low uncertainty score for its impact potential (0.04) and higher uncertainty regarding its spread potential (0.21) due to a paucity of information on seed bank formation and seed storability. However, further research on the plant's growth dynamics and interactions with other species is necessary to inform responsible decision-making regarding moringa’s cultivation and management in New Zealand.