A recent study reveals that the Amazon rainforest in South America is 'getting fatter'—the average size of trees has increased by 3.2% every decade, a trend that correlates with the rise in atmospheric carbon dioxide levels.
This research was conducted by a global team of tropical rainforest scientists involving more than 60 universities from South America, the UK, and other regions. The related paper was recently published in the UK journal Nature Plants.
The research team monitored 188 fixed plots in the Amazon rainforest for more than 30 years, during which time the atmospheric carbon dioxide concentration increased by nearly one fifth. In each plot, researchers measured the diameter at breast height of every tree, identified their species, and returned multiple times to track the growth of these trees.
To understand the dynamics of the Amazon ecosystem, the team also established a systematic forest monitoring framework, with ground plots at the core. This framework tracks the survival status of every tree and species, and at some sites, carries out enhanced monitoring of the carbon cycle process.
The results show that both large and small trees in the Amazon rainforest are increasing in size, which coincides with the 'fertilization effect' brought about by the increased atmospheric carbon dioxide. The researchers stated that large trees make a tremendous contribution to carbon dioxide absorption, and this study further confirms that. Even in the context of climate change, the Amazon rainforest still shows remarkable resilience in terms of carbon sequestration.
The study also emphasizes the devastating impact of Amazon deforestation, pointing out that many large tropical trees are hundreds of years old, and simply planting new trees cannot substitute for the role of primary forests in either carbon storage or biodiversity.
The researchers believe that how giant trees cope with intensifying climate threats and how they disperse seeds has now become a key issue. The only way for the giant trees of the Amazon rainforest to remain healthy is to maintain the integrity of the local ecosystem. If deforestation is allowed to continue, the resulting threats will multiply, eventually leading to the disappearance of these giant trees.