Belgian cities are home to other exotic plant species than the cooler countryside. But “summers like the current ones could make those species dominate everywhere,” the researchers warn.
“The hot air envelops cities like a blanket on hot days,” explains Jonas Lembrechts (UAntwerp).
“In addition, the soil in the city is often drier than in the surrounding countryside. More water drains away and the extra heat ensures faster evaporation. Until recently, trees of warmer origin were therefore forced to be confined to the city, because the climatic conditions the countryside were simply not suitable.As the summers get drier and warmer, but our winters are not so cold either, the right conditions for their development are expanding.
This increases the chance that urban exotics, such as the tree of heaven or the Anna Pauwlona tree, will also be more and more present in the countryside. This spread could be at the expense of indigenous biodiversity in rural areas, which has already been weakened by drought and heat waves.