Tree roots continue to grow during the winter, contrary to previous assumptions, according to an international study involving the University of Antwerp.
"When temperatures drop, the trunk and woody roots of trees stop growing. That was the common belief," the university stated in a press release on Thursday. "Research has now shown that roots underground remain active even in winter."
The roots of a tree often spread as widely as its branches and leaves above ground. They are essential for nutrient uptake, storage of resources, water absorption, and anchoring the tree. Despite their importance, scientific knowledge about root growth is limited.
It was long assumed that both roots and trunks stop growing in autumn because of the cold weather. New research disproves this assumption, showing that woody roots continue to grow during colder months, even after the trunk has stopped.
“Our research focused on the main tree species found in the forests of Western Europe,” said Lorène Marchand from the University of Antwerp. Researchers collected roots and trunk cores from mature beech and birch trees in the forests around Brasschaat over two years. They also conducted experiments with young trees grown in pots in Brasschaat, Barcelona, and Oslo. In total, 330 trees were studied, with over 1,000 root samples collected.
“We made a surprising discovery,” Marchand continued. “As expected, the wood in the trunk stopped growing in autumn when the leaves fell, but the wood in the roots continued to grow slowly but steadily throughout the winter, until the following spring when new leaves developed.”
The growth pattern in the roots is not location-dependent. Researchers observed similar results with young trees examined in autumn in Spain, Belgium, and Norway, despite varying temperatures. This discovery could change our understanding of how trees grow and manage their carbon reserves.
