Long-Lived Pioneer Trees Play a Much Larger Role in Carbon Storage
Mon, August 15, 2022

Long-Lived Pioneer Trees Play a Much Larger Role in Carbon Storage



Covering 30% of the Earth's land surface, forests can absorb 2.4 billion tons of carbon dioxide annually. They play a huge role in regulating the climate and are critical to addressing the impact of climate change. But, with the huge benefits they provide our planet, Louis Verchot, Director of the Forests and Environment Programme at the Centre for International Forestry Research (CIFOR), said that their role in addressing climate change is only beginning to be understood.

“We have an attention on forest issues which we perhaps haven’t seen in over 20 years. Because they were treated in isolation and were forests for the sake of forests it didn’t go nearly as far as many people had hoped at the time,” Verchot said. 


The Role of Forests

Carbon dioxide concentration in the atmosphere has increased by 31% since the beginning of the industrial era. According to the International Union for Conservation of Nature (IUCN), around 25% of global emissions come from the land sector, the second-largest source of greenhouse gas emissions after the energy sector. Half of this percentage comes from deforestation and forest degradation. This is where the role of forests comes in. Previous reports have shown that forests absorb approximately 2.6 billion tons of carbon dioxide every year. 

Forests also help our planet in many ways such as protecting biodiversity, regulating ecosystems, supporting livelihoods, and more. They can act as a safety net for local communities, helping them cope with climate shocks. For instance, mangroves can hold back storm surges or cyclonic flooding. Reports show that about 1.6 billion people across the world, which is nearly 25% of the world’s population, rely on forests for their livelihoods, many of whom are the world’s poorest.

However, with the increasing deforestation across the world, we can’t fully maximize the climate benefits of forests. More and more people are demanding forest products, risking the remaining trees worldwide. Worse, humans are not doing all that they can to save all forests or restore them. Scientists say that halting the loss and degradation of natural systems and promoting their restoration can potentially contribute to over one-third of the total climate change mitigation. At the same time, restoring 350 million hectares of degraded land could sequester up to 1.7 gigatonnes of carbon dioxide equivalent annually.  



According to Climate Change News, an independent news site dedicated to bringing important climate stories to as large an audience as possible, Aly Abou-Sabaa from the African Development Bank said that the world’s natural assets have not been given any meaningful value to the extent that their uses are being overexploited. 

“It is important that the forests get the right value because it is important for the people living in these forests and exploiting them to recognize that the impact is of unsustainable exploitation of these forests but also to understand how much this exploitation is costing the environment and the whole world globally,” he said. 

Fortunately, many countries are launching their own initiatives to keep the global temperate increase within the 2-degree target. China, for instance, launched the Shandong Ecological Afforestation Project that planted trees on 66,915 hectares of barren mountainous slopes and saline coastal areas. This has increased forest cover, reduced soil erosion, and improved the environment and biodiversity. In Mexico, a climate change program contributed to improving the livelihoods of about 4,000 forest communities through sustainable management of forest goods and services. 



Long-Lived Trees Contribute More to Carbon Storage

As a whole, forests can absorb billions of carbon dioxide from the atmosphere. But, not all trees are the same. Some trees can store more carbon dioxide than others. A recent study led by Nadja Rüger, a scientist with the German Center for Integrative Biodiversity Research, found that a group of trees that grow fast, live long lives, and reproduce slowly, called long-lived pioneers, play a much larger role in carbon storage than previously thought.

According to Science Daily, an American website that aggregates press releases and publishes lightly edited press releases about science, most existing Earth system models that are used to forecast global climate decades from now represent the trees in a forest as all basically the same. This includes those used by the Intergovernmental Panel on Climate Change. However, many scientists have argued that not all trees contribute the same to our planet. 

"People have been arguing about whether these long-lived pioneers contribute much to carbon storage over the long term. We were surprised to find that they do,” Caroline Farrior, an assistant professor of integrative biology at The University of Texas at Austin, said. 

According to Cosmos Magazine, a science magazine produced in Australia with a global outlook and literary ambitions, the researchers used 40 years of data from 200,000 trees from 282 species collected from a tropical rainforest in Panama, one of the most well-researched tropical rainforests in the world. With the data gathered, the researchers improve the models' accuracy, helping to start answering questions about what drives forest composition over time and what factors affect carbon storage. 

“We show that the variation in tropical forest species’ growth, survival and reproduction is important for predicting forest carbon storage,” Farrior said. 

Previously, scientists identified that trees use different strategies during their development: “pace of life” distinguishes “fast” species that grow and die quickly,” while “slow” species grow slowly and reach old age. However, the team discovered that stature and fertility can differ irrespective of the trees’ pace of life. To plot these different strategies in computer models, the team simulated how trees grow, die, produce offspring and compete for light as they would in a real forest.



After this process, the scientists compared this with the observed development of real, secondary forests regenerating after being cleared for timber or agriculture. Rüger said that this data-driven modeling approach presents a new method to predict the development of species-rich forests that can save time and resources. “Basically, we were able to reduce the forest to its essence, and that was only possible because we know so much about the tree species in the forest in Panama,” she added. 

However, it is still unclear to what extent tropical rainforests can help soak up excess carbon dioxide in the atmosphere produced by burning fossil fuels. Still, this study published in the journal Science could be used to craft more effective conservation plans as well as to prioritize the protection for forests with larger numbers of long-lived pioneers.