Alien species can have massive impacts on native biodiversity, ecosystem functioning, and human livelihoods. Assessing which species from currently cultivated alien floras may escape into the wild and naturalize is essential for efficient and proactive ecosystem management and biodiversity conservation. Climate change has already promoted the naturalization of many alien plants in temperate regions, but whether it is similar in (sub)tropical areas is insufficiently known. In this study, we used species distribution models for 1527 cultivated alien plants to evaluate current and future invasion risks across different biomes and 10 countries in southern Africa. Our results confirm that the area of suitable climate is a strong predictor of naturalization success among the cultivated alien flora. In contrast to previous findings from temperate regions, however, climatic suitability is generally predicted to decrease for potential aliens across our (sub)tropical study region. While increasingly hotter and drier conditions are likely to drive declines in suitability for potential aliens across most biomes of southern Africa, in some the number of potential invaders is predicted to increase under moderate climate change scenarios (e.g. in dry broadleaf forests and flooded grasslands). We found that climatic suitability is expected to decline less for aliens originating from continents with the tropical biome or from the Southern Hemisphere. In addition, we found that the climatically suitable area will decline less for aliens that have already naturalized in the region. While the number of potential invaders may decrease across southern Africa under future climate change, our results suggest that already naturalized aliens will continue to threaten native species and ecosystems.

中文翻译：

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在气候变化的影响下，南部非洲目前种植的外来植物群的入侵风险预计会下降


外来物种可能对本地生物多样性、生态系统功能和人类生计产生巨大影响。评估目前栽培的外来植物群中的哪些物种可能逃逸到野外并自然化，对于有效和积极主动的生态系统管理和生物多样性保护至关重要。气候变化已经促进了温带地区许多外来植物的自然化，但（亚）热带地区是否也有类似情况尚不清楚。在这项研究中，我们使用 1527 种栽培外来植物的物种分布模型来评估不同生物群落和南部非洲 10 个国家当前和未来的入侵风险。我们的结果证实，气候适宜的地区是栽培外来植物群归化成功的有力预测因素。然而，与之前在温带地区的发现相比，我们的（亚）热带研究区域的潜在外星人的气候适宜性通常预计会下降。虽然日益炎热和干燥的环境可能会导致南部非洲大多数生物群落对潜在外星人的适宜性下降，但在一些地区，在温和的气候变化情景下（例如在干燥的阔叶林和洪水泛滥的草原），潜在入侵者的数量预计会增加。我们发现，对于来自热带生物群落大陆或南半球的外星人来说，气候适宜性预计下降幅度较小。此外，我们发现，对于已经在该地区归化的外国人来说，气候适宜地区的下降幅度会较小。 虽然在未来的气候变化下，南部非洲潜在入侵者的数量可能会减少，但我们的研究结果表明，已经归化的外来物种将继续威胁本土物种和生态系统。