Global biodiversity assessments have often suggested that the impacts of invasive alien species are greatest in wealthy countries of the Global North. A new study, however, challenges this notion and establishes that the severity of environmental impacts is generally higher in the Global South and calls out research bias for distorting the global picture.
The study, published recently in Science journal, combines two global datasets: GIDIAS, which contains more than 22,000 documented impacts involving over 3,300 invasive alien species from more than 6,700 scientific and grey-literature sources across 172 countries, and SInAS, which records the distribution of more than 39,700 alien species worldwide.
Considering research effort and the number of reports are much higher in the Global North, simply counting invasive species or documented impacts can make the region appear disproportionately affected. To better understand the impact, researchers, Sven Bacher, Petr Pyšek and Hanno Seebens used the IUCN’s Environmental Impact Classification for Alien Taxa (EICAT) under which an impact is considered severe when an invasive species causes a decline in a native population, local extirpation or global extinction.
Rather than simply counting how many invasive species or impacts have been recorded in a region, the researchers calculated average impact severity: the proportion of documented impacts that are severe. This was intended to reduce the effect of differences in research effort between countries.
The key findings include higher average impact severity in the Global South, the influence of research bias on assessments of invasive species impacts, the particular vulnerability of emerging economies, and the role of governance and management capacity in determining impact severity than large economies in the Global North.
The paper identifies India as one of the large, high-income developing economies where this pattern is visible. India has relatively high absolute numbers of documented impacts, but also a distinctly higher average impact severity than large economies in the Global North.
One of the biggest takeaways from the study is that weak governance and limited management capacity act as major drivers of high impact severity. Failure to recognise the Global South as facing the highest IAS impacts diverts attention away from the most threatened regions.
Previous research has identified emerging economies as countries likely to see the largest increases in alien species numbers in the near future as a result of strong economic development, potentially leading to more impacts, many of them severe. By contrast, wealthy countries of the Global North may have high introduction rates of alien species but also stronger governance and better management capacity as compared with the Global South, allowing them to implement policies and manage invasive species more effectively. The paper shows that good governance and effective management can reduce the impacts of biological invasions across most taxa and ecosystems.
Banner image: Invasive giant African snails spotted in Kerala. Image by Drajay1976 via Wikimedia Commons (CC BY-SA 3.0).
Credits
