This World Tree Day, the first day of Spring, recalls the importance of these living beings. Trees support biodiversity, fix the soil and help control the climate. But as the climate changes, so will the trees. How to deal with this uncertainty?
Just look at the differences in the landscape to see: the trees are different in the Atlantic Minho and in the Algarve with a Mediterranean climate. Oaks, pines and eucalyptus dominate in the North and, in the South, cork oaks and holm oaks tolerate drought better. If the climate is different, so are trees. And if the climate changes, so do the trees. THE Laurissilva forest, which still covers the northern slopes of the island of wood, is an example of that: until the last Ice Age, it covered part of continental Europe, including Portugal, but only resisted in the mild and humid climate of the islands.
The challenge facing humanity today is immense: halting ongoing climate change and adapting to a changing climate. Monumental trees, which have survived several centuries, are increasingly threatened. Exposed to warmer summers and irregular rains, they wilt or eventually succumb to the disease.
The idea of indigenous vegetation will also inevitably have to be revised. It is certain that the oaks once dominated the forests of the Iberian Peninsula. But, taking into account that the climate will continue to evolve, can it be assumed that the oaks will adapt?
When the earth warms up, and trying to imagine the landscapes of the future, perhaps one can look south. In Morocco, more drought-resistant trees thrive, which halt the advance of deserts. And much more beyond, in southern limit of the Sahara desert, there is no lack of resilient trees. Fruit trees, such as jujube or mango, which are resistant to drought, help to feed local populations.
It may seem unreasonable to think of trees with a dry tropical climate. However, fruit is already being produced in mainland Portugal that would have been unthinkable in a pre-industrial climate: anona, papaya or mango. It is known that the Mediterranean basin has warmed more than the average for the planet, making it one of Global Warming Hot Spots. That is why, without prejudice, it is essential to test new species and understand the trees of the future. In 2050, the climate will be warmer, when the trees planted today will have grown.
Does this mean that native trees must be forgotten? Quite the opposite. Keeping them will require more dedication. There are teams committed to saving the cork oak or to recover the trees along the rivers. And history shows how some trees resist climate change. The millennial olive tree in Mouriscas has almost 3000 merciless summers and, even so, continues to produce olives. Millennial olive trees like this one, not only better resist climate variations, but also produce better quality olive oil.
Trees will always be important for the planet and for humanity. They regulate the climate, protect the soil from erosion and support biodiversity. The roots fix them in the same place, but the changing climate will leave marks. To maintain life, and for our resilience, let us know how to plant new trees and take care of those that have seen us grow.