Madrid is not only one of the five cities with the most trees and green areas in Europe according to the European Environment Agency, but the FAO has been doing it for six years recognizing it as “Tree City of the World”. And yet, it is at the bottom of the continent in ‘useful cup’ (with only 9.4%). It has many trees, but they are useless.
And that, far from being a Madrid curiosity, is the best possible summary of the great Spanish problem with urban trees.
What happens to the trees? The short explanation is that they are the cheapest cooling tool available. It’s not a secret. However, the lesson we need to learn is not a crude “we need more trees.” That is what explains the ‘contradiction’ of Madrid.
We need more trees, yes. But we need trees of the right species, covering the right layers, planted where they are needed and provide more, and well watered. That is, we need a comprehensive plan that stops seeing trees as inconveniences and begins to see them as opportunities.
How do we know all this? The work of Mohammad A. Rahman, Senior Lecturer in Urban Horticulture at the University of Melbourne It is very useful to study how they really work the trees. The results are contradictory, but very interesting.
According to their work, for example, the trees in Melbourne (a city with a temperate climate) reduce the radiant heat absorbed by pedestrians by up to 18 degrees compared to an open street with the same characteristics. In the cold climate of Munich, layered vegetation (the combination of trees, shrubs and ground cover) reduces heat stress in summer by up to 8 degrees.
In Hong Kong, on the other hand, where the climate is subtropical and humid, dense vegetation increases the humidity of the environment and limits cooling. That is why researchers are beginning to agree that, even maximizing the use of trees, it is difficult for trees cut more than 20% of future urban warming.
But be careful, 20% is a lot. Above all, because Spain has a lot to do. According to ISGlobalthe Spanish cities are at the bottom in canopy coverage on urban land: 5.5% in Seville, 8.4% in Barcelona or 9.4% in Madrid compared to 33.3% in Berlin or 23.3% in Frankfurt.
To give us an idea, the average of the 93 cities was 11% and only Athens (with 3%) was below Seville.
We need to take this seriously. Historically, Spain has bad care of its urban trees. And that “evil” can be summarized in very few words (“few resources, bad management and political decisions isolated from any current technical knowledge”), but it has a very difficult solution.
Fundamentally because all this evidence translates into “planting more trees is cheap and saves lives”; but its implementation systematically fails.
Image | Ch Photography
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