Climate change is not only the native species of plants and animals but also the ones that humans have introduced to new regions.
A recent study has revealed that the number of non-native species is increasing at an unprecedented rate, especially in North America, Europe, and Australia, where they pose serious threats to biodiversity and ecosystems.
Non-native species come from within and outside the continents
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Non-native species are those that have been moved by humans, intentionally or unintentionally, beyond their natural range.
Some of them are beneficial for agriculture, forestry, or horticulture, while others are harmful and invasive, meaning that they can outcompete, displace, or hybridize with native species, alter ecosystem functions, or transmit diseases.
According to the study published in the journal Science Advances, more than half (57%) of the non-native plant species that have established themselves in new areas on the continents of Europe, Australia, and North and South America originally came from their continent.
The study found that the intracontinental spread of non-native plants was mostly from regions near the equator toward the poles, reflecting the climatic preferences of the species.
For example, in Europe and North America, many of the non-native plants came from the Mediterranean and subtropical regions, while in South America, they came from the tropical and subtropical regions.
However, the study also showed that intercontinental introductions of non-native plants were still common, especially in Australia, where only 15% of the non-native plants came from within the continent.
The researchers attributed this to the high degree of isolation and endemism of the Australian flora, which makes it more vulnerable to invasions by exotic species.
Climate change will accelerate the intracontinental spread of non-native species
The researchers also examined the role of human, climatic, and geographic factors in influencing the intracontinental spread of non-native plants.
They found that long distances and strong climatic differences hindered the spread, while high human population density, trade volume, and land use facilitated it.
The study predicted that climate change will increase the chance of non-native species spreading to new regions within the same continent, as the climatic conditions will become more suitable for them.
The estimated number of established non-native species in Australia will increase by 36% between 2005 and 2050, while in Europe and North America, it will increase by 28% and 25%, respectively.
The study warned that the intracontinental spread of non-native species will have significant ecological and economic impacts, as they can disrupt native biodiversity, ecosystem services, and human well-being.
According to the researchers, effective prevention, early detection, and rapid response measures are needed to reduce the risks and costs of biological invasions.
The study also highlighted the importance of international cooperation and information sharing to monitor and manage non-native species across continents.
