Factors governing the naturalization-to-invasion transition of exotic plants in Shenzhen, China

Understanding factors increasing the probability of exotic plants becoming invasive is crucial for designing appropriate management strategies to mitigate the detrimental effects of invasive plants on rapidly urbanizing areas. However, no study to date has attempted to determine how various factors may affect the naturalization-to-invasion transition of exotic plants in these areas. Here, we took Shenzhen, one of the largest and most rapidly urbanizing cities of the world, as a case study to explore how various factors may affect the naturalization-to-invasion transition of exotic plants in rapidly urbanizing areas, with an emphasis on exotic plant invasion in urban forests. Our results showed that 33.5% of the 349 naturalized exotic plant species in Shenzhen have become invasive. We found strong evidence that plant attributes and environmental factors have considerable effects on the naturalization-to-invasion transition of exotic plant species in Shenzhen. In contrast, there was little evidence that any socio-economic factor promotes the naturalization-to-invasion transition of exotic plants in Shenzhen. Our findings suggested that although human activities facilitated the initial establishment of exotic plant species in rapidly urbanizing areas, the naturalization-to-invasion transition of exotic plants in these areas appeared to be governed largely by biotic and environmental factors.