Studies suggest old large trees are best at absorbing carbon
The enduring value of trees is their ability to absorb carbon dioxide from the air. As every school child learns, trees act like lungs as they absorb carbon and produce oxygen through the photosynthesis process.
Deforestation reduces the amount of carbon that can be absorbed, which environmentalists say significantly contributes to climate change. Planting new trees is one way to stave off deforestation, but new studies suggest that older trees provide the most efficient means of carbon capture.
A 2014 study from the U.S. Geological Survey Western Ecological Research Center analyzed data on 673,046 trees from 403 species in monitored forest plots, in both tropical and temperate areas around the world. This study found that the largest trees gained the most mass each year in 97% of the species. Large trees hold the most carbon in their roots and trunks. They can capture large amounts of carbon by capitalizing on their additional leaves and their reach to the top of the tree canopy for consistent access to the sun.
Researchers from the University of Hamburg, Germany, suggest in a 2017 study of natural tropical forests that trees maintain high carbon accumulation rates toward the end of their lives, accumulating 39-50% of their final carbon stock in the last quarter of their lifetimes.
What do studies suggest about forest management and climate change? Unfortunately, one answer may not be just a matter of planting many more new trees to make up for deforestation. Previous studies done on managed forests — places where trees have been planted at about the same time and are all similar species — show that managed forests take up a lot less carbon than unmanaged forests of the same age. For now, it may be best to consider the importance of old growth forests in their more efficient carbon storage capacity and their important role in combatting climate change.
Sources:
“Tropical Trees Maintain High Carbon Accumulation Rates Into Old Age”, August 16, 2017.