Trees in cities worldwide grow faster than those in surrounding areas due to the urban heat island effect, but trees everywhere are growing faster than 50 years ago, according to an international team of researchers.  Led by the Technical University of Munich (TUM), the team took heartwood samples from almost 1,400 mostly mature trees in and around Munich, Berlin, Paris, Brisbane, Cape Town, Hanoi, Houston, Prince George (British Columbia) and Santiago de Chile, in order to cover a range different climate zones from boreal to subtropical. TUM chair of forest growth and yield science Professor Hans Pretzsch said: “While the effects of climate change on tree growth in forests have been extensively studied, there is little information available so far for urban trees. “We can show that urban trees of the same age are larger on average than rural trees because urban trees grow faster.”