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The Amazon, that mighty tropical forest that today hosts the 50,000 participants in the climate change conference (COP30), is undergoing a transformation so profound that even human impacts have altered its evolutionary history. The changes generated, ranging from selective logging to deforestation and fires, have changed the functionality of their forests and it could take decades before they return to having a composition similar to that of their predecessors, indicates a study published in Biology of global change.
From Lancaster University, UK, Brazilian ecologist Cassio Alencar Nunes explains that deforestation is not the only threat to tropical forests. Throughout the Amazon, for example, the area of forests with some disturbance is greater than that which is deforested. Modified forests occupy at least 1.27 million square kilometers, the equivalent of 23% of the forests that still persist in the region. “What we did was analyze how different disturbances affect tree diversity,” he says.
They did so on three fronts. Not only by studying taxonomy – that is, the diversity and number of species – but also the variety of functions that trees and phylogenetics perform. “We evaluate how each species relates to each other in terms of evolution,” clarifies the co-author of the research on the last point. In all three cases, remember, they discovered that the variety is smaller after the different alterations and that its modification by humans explains 55% of this effect.
To reach this conclusion they resorted to an army of information. As part of the Sustainable Amazon Network (RAS) have taken advantage of the fact that, since 2010, they own 250 plots in the eastern Amazon of Brazil, in Paragominas and Santarén. In these there are 55,000 trees which, through different works and people, have been studied and measured, becoming the input to answer the question that Alencar Nunes and his team asked themselves. The RAS lots served as a real-life laboratory for testing theories. In some they found signs of fire or deforestation in the last 20 years, while others remained untouched. Therefore, they were able to compare the path taken by an intervened forest versus one that was not.
“It’s a very robust work,” adds the ecologist, underlining the number of registrations taken into consideration. Furthermore, since the plots have been examined since 2010, they were also able to see what the composition of Amazonian secondary forests is like: those that arise and grow after an ecosystem has been reduced to almost nothing. “They have the lowest levels of local diversity and are the most diverse from intact forests, regardless of region,” the study specifies.
In secondary forests – which currently occupy up to 235,000 square kilometers across the Amazon – pioneer species predominate. In this case, trees capable of emerging from the hostile conditions that, for example, a fire leaves behind, but which have different functions than the slow-growing trees that were there before. “They are trees that reach 20 meters in height, when others can reach up to 35 or 50 meters,” explains Alencar Nunes. “This implies that the ecosystem has more light, more heat and less humidity. It changes the way everything is structured and functions.”
Ahead of COP30, the research message is strong. First of all, disturbance and degradation of the Amazon forests must be avoided at all costs, since the intact ones are much richer and have a different species composition. But the second thing is that even altered primary forests continue to host “a fairly significant number of species, functional types, and evolutionary lineages compared to secondary forests.” It is therefore essential to avoid deforestation or further alterations, especially at this advanced stage of the climate crisis.
“In this sense, we believe that the mechanism of the Tropical Forests Forever Fund (TFFF) is positive because it values all existing forests, even if they present some disturbance,” he comments regarding the financial instrument that President Luiz Inácio Lula da Silva presented days before the official start of COP30. The fund, in addition to operating according to the logic of investments, aiming to raise 125 billion dollars and guarantee that at least 20% of payments made to countries with tropical forests go to indigenous populations and local communities, is based on an idea different from other proposals: that those who keep the forests standing are paid, even if there have been interventions.
With the trees of the Amazon it happens as with everything there: every loss in that jungle is a loss for the Earth. And while a single Amazonian hectare can contain more than 300 species, all of Europe has around 450 native species, the authors of the study recall.
