By Nikole Cantoara*
Although increasing impacts from fire, severe droughts, windstorms, edge effects, and extreme weather events are putting the Amazon rainforest under growing pressure, the results show that the forest still demonstrates recovery capacity. However, this regeneration does not mean a full return to its original state.
This finding is the result of a new article conducted by researchers from IPAM (Amazon Environmental Research Institute), published in the scientific journal PNAS (Proceedings of the National Academy of Sciences). The study began in 2004, when researchers visited the southern Amazon region in Mato Grosso to monitor the impacts of forest fragmentation and degradation. At the time, climate models already indicated that this portion of the biome would be more affected by extreme droughts and, consequently, more susceptible to fires due to high rates of deforestation and fragmentation.
The scientists established three treatments at the Tanguro Research Station, an open-air laboratory run by IPAM, and simulated different fire regimes to understand how the forest would react to different degradation conditions: a plot burned annually, another burned every three years, and a control area with no fire.
Contrary to expectations, the results showed that less frequent fires can cause more severe impacts. “We expected the annual fire to have a greater effect, but we observed the opposite. Fire every three years generates greater intensity, with taller flames, because there is an accumulation of biomass on the ground, which exceeds the trees’ resistance and increases their mortality,” explains Leandro Maracahipes, a researcher associate at IPAM and the lead author of the study.
In parallel, extreme drought events recorded in 2007 and 2010 intensified the impacts, raising tree mortality by up to 30%. The study analyzed different types of disturbances affecting the forest, and in one of the recorded extreme events, a windstorm was responsible for knocking down 5% of the trees in the area, equivalent to the mortality expected over an entire year.
All this forest degradation was even more intense at the forest edges. “The scenario is worrying. Deforestation not only affects the area directly cleared but also alters the conditions of the surrounding forest, making it more vulnerable to fire, windstorms, and forest degradation. The edges of these fragments are especially critical, since that is where most fires start, almost always due to human action,” reports Paulo Brando, a researcher associate at IPAM and one of the leaders of this research.
Despite the impacts caused, it was observed that forests can regenerate, provided that certain factors, such as the removal of anthropogenic disturbances and the conservation of areas near degraded sites, are present.
This recovery process is directly linked to seed dispersal, which allows vegetation to repopulate recovering areas. With proximity to conserved forests, seeds can reach these environments, mainly through animals.
“The tapir, for example, helps carry seeds of more resilient, slow-growing species that store carbon for hundreds of years to recovering areas. Without this dispersal, the regeneration process is compromised,” highlights Maracahipes.
This flow of species is essential for regeneration to advance over time, especially with the arrival of more resilient and slower-growing species, which help reestablish forest structure, favoring the emergence of new plants and the recomposition of forest cover.
Scientists had warned that forests severely degraded by multiple consecutive disturbances were heading toward collapse, adopting “alternative stable states” more susceptible to new extreme events. The fear was that these areas would reach the so-called tipping point: the moment when the forest loses its capacity to regenerate and transforms into another type of environment, in an irreversible process.
“However, degraded forests present a more complex picture. The study shows that, even under enormous pressure, our experimental forests did not lose their fundamental ability to remain forests. Despite dramatic collapses in biodiversity and structural complexity, they maintained the capacity to recover some of their fundamental characteristics within a decade or more. This is a significant finding and, with caution, yes, it is a reason for optimism,” comments Brando.
The results reinforce that, although the Amazon rainforest still shows regeneration capacity, this process depends on the surrounding conditions. The persistence of disturbances such as fire and deforestation, combined with fauna loss and forest fragmentation, can compromise this recovery over time.
For the authors, curbing degradation and maintaining connectivity between forests becomes essential not only to ensure regeneration but also to prevent these ecosystems from approaching a tipping point. “If we control disturbances and maintain seed sources and animal dispersers, the forest has the capacity to recover. But this process has limits and depends directly on our actions,” concludes Leonardo Maracahipes-Santos, a researcher at IPAM and one of the authors of the article.
