Climate change is affecting the distribution of plants and animals around the world. As the planet warms, some species are shifting their ranges to higher latitudes or altitudes, seeking cooler and more suitable habitats.
However, not all species are moving at the same pace or in the same direction.
A recent study by an international team of researchers found that non-native plants are migrating north faster than native plants, potentially altering and damaging ecosystems.
Non-native plants benefit from fewer and weaker winter freezes
However, as climate change progresses, the frequency and intensity of killing freezes are decreasing, especially in the subtropical regions of North America, Europe, and Australia.
This allows non-native plants to survive and expand their ranges northward, where they may encounter less competition and predation from native species.
The study, published in the journal Science Advances, analyzed data from more than 12,000 plant species across four continents and found that 57% of the alien plant species that have successfully established themselves in new areas came from their continent.
They usually originated in warmer regions closer to the equator and moved towards the poles as winters became milder.
The proportion of intracontinental spread was particularly high in Europe and North America, where non-native plants accounted for 76% and 69% of the total alien flora, respectively.
The researchers also examined the role of human, climatic, and geographical factors in influencing the intracontinental spread of non-native plants.
They found that long distances and strong climatic differences hindered the movement of non-native plants, while human population density and trade facilitated it.
The closer an area was to the original distribution range of a non-native plant and the more similar the climate was, the easier it was for the plant to colonize.
Non-native plants can outcompete native plants for resources, alter soil properties and nutrient cycles, affect fire regimes and hydrology, and facilitate the invasion of other non-native species.
Some non-native plants can also harm human health by causing allergies, poisoning, or injuries.
The study estimated that the ecological damage caused by non-native plants could result in an annual economic loss of at least 400 billion dollars worldwide.
The authors suggested that more research is needed to understand the impacts of non-native plants on different ecosystems and regions and to develop effective management strategies to prevent or mitigate their negative effects.
The study also highlighted the importance of considering the effects of killing freezes on plant distributions in future climate change projections.
The authors warned that as killing freezes become less frequent and less severe, more non-native plants will be able to move northward and invade new areas, posing greater challenges for conservation and restoration efforts.
