Autumn colors are appearing later and later.

BarcelonaIt's the heart of autumn, and forests across the country have been displaying the classic and spectacular yellow, red, and orange hues of this time of year for weeks. But the colors of autumn are arriving later and later in our country due to the effects of the climate crisis, according to a study by Meteocat published this Friday based on data from the Phenological Network of Catalonia (Fenocat). The report concludes that the change in leaf color of deciduous trees is being delayed by an average of 2.1 days per decade in Catalonia. The study focused on the beech tree, which is particularly colorful at this time of year. In fact, beech forests attract thousands of visitors every autumn because of their spectacular display. Data indicates that some beech forests are experiencing a delay in leaf color change of up to 3 or 4 days per decade, such as those found at Roca Tiraval in Bagà (Berguedà) or Castellterçol (Moianès). This shortening of the natural period puts these trees at risk in the future.

"Deciduous trees go through a dormancy period to be able to sprout vigorously in spring, and this period is shortening, which affects their development," Xavier de Yzaguirre, a technician at Meteocat and coordinator of the Fenocat network, told ARA. In Catalonia, beech forests are found mainly in the Pyrenees, the Pre-Pyrenees, Montseny, and nearby areas, and to a lesser extent in Els Ports and Terres de l'Ebre.

De Yzaguirre points out that the beech tree is not a typical Mediterranean wild tree, but rather one native to Central Europe, and warns that this makes the species highly vulnerable to global decline. "Since we are at the territorial limit of this tree's distribution, we see that in the medium to long term this situation could lead to the disappearance of some beech forests in our country," the expert states.

A particularly sensitive tree

According to De Yzaguirre, the beech tree is "especially sensitive" to rising temperatures and changes in humidity resulting from the climate crisis, which is causing changes in the behavior of this species in Spain. "Increasingly higher temperatures and a lack of humidity are causing increased water stress in these trees, which will ultimately affect their geographical distribution," the expert explains. "We are beginning to see that beech trees are moving to higher altitudes to better withstand these changes," he adds. De Yzaguirre points out that, according to climate projections made by Meteocat, rainfall will be 20% lower on average within 50 years, and temperatures will continue to rise unabated. All of this foreshadows devastating effects on beech trees. "It is a tree that will be particularly affected by the climate crisis," the expert concludes.

The beech tree experiences its peak leaf color change during the second half of October and the first half of November. This year, this process is considerably more typical than in recent years of drought and unusually warm autumns, but all data indicate that this year's apparent normality will be an exception.

The Meteocat analysis is based on thousands of observations of beech trees made throughout the country over the last thirteen years. The Fenocat network has eighty volunteer observers and a total of more than one and a half million observations of different plant species collected since 2013, of which 15,200 are of beech trees in regions such as Vallès Oriental, Osona, Vall d'Aran, Ripollès, and Berguedà.