Urban warmth is a phenomenon of increased air temperature in cities compared to the rest of the environment, and scientists suggest that with rising temperatures around the world and increasing urbanization it is quite important to understand how the heat captured by cities affects our trees – and vice versa.
A team of scientists from the Munich Technical University (TUM) has been following the pattern of growth of 1,383 woods over the past 150 years. What they found was that, although city trees generally "get the battle", it depends on the end of the world that grows. Throughout all these zones, if viewed as a whole, the rate of growth of rural and urban trees has not increased significantly since the sixties of the last century. In general, urban trees have grown up to 25 times faster than rural ones.
"We have shown that urban trees are the same age as in the wild on average – bigger, because it is growing faster. Although this difference is about one quarter for trees aged about 50 years old, it is slightly below 20% for trees of 100 years old, "said Hans Riczsch, a member of the scientific team.
Trees from Different Climatic Conditions
All data was collected from trees in and around Berlin and Munich in Germany, then in Brisbane, Australia, Cape Town, South Africa, Hanoi, Vietnam, Houston, Texas, Paris, France, Prince George, Canada , in Santiago de Chile and Sapporo in Japan. All these cities are chosen because of 4 different climate – subpolar, Mediterranean, moderate and subtropical.
The largest growth of urban trees has been observed in sub-polar regions, while moderate climate in urban areas is slower than their rural relatives. The differences almost did not occur in the growth of Mediterranean trees, while the subtropical urban grew faster than those mentioned in the sixties, but has since equated with rural growth.
Scientists consider the acceleration of growth from the sixties as a consequence of carbon dioxide emissions, Previous studies have revealed that as long as there is water, the warmer climate favors the growth of trees.
Accelerated Growth and Age
Trees and plants can expand their growing season in a warmer environment and also increase the rate of photosynthesis thanks to the fertilizing effect of carbon dioxide. In cities where trees fail, such factors as poor soil quality or lack of water are counteracting the heat that contributes to growth, the scientists point out.
However, apart from the fact that urban trees grow faster – faster and older and need to be changed more often with shoots. The research was published in the journal Scientific Reports.