January 27th, 2014 by
Large, old tree.

Large, old tree. Credit: Guyon Morée

Our elders offer a lot to society that younger generations may not as readily provide. They have more years of experience and wisdom to impart and rich histories to share. But our species is not the only one in which older individuals provide benefits that the young can’t always make up for.

We already know that old growth provides benefits and plays roles in forests that younger trees can’t always fulfill. Dr. Jerry Franklin, American Forests Science Advisory Board member and forest ecologist at the University of Washington spoke with us last August about what a few of these benefits are. Large, old trees provide the large, deep cavities where animals like owls and opossums like to make their cozy homes, for example. Younger trees have often not weathered the same wear and tear of life that leads to the formation of these cavities, especially in ecosystems that lack cavity-creating species like woodpeckers.

Now, though, a recent study published in Nature has found that something long believed about older trees — that trees’ growth slows as they age — isn’t so. On the contrary, older trees speed up growth. Though similar trends have been studied before in certain species, the new study analyzed more than 600,000 trees of 403 species and found growth acceleration with age across the board.

Lead author Dr. Nathan Stephenson, an ecologist with the U.S. Geological Survey, explains in a Smithsonian Tropical Research Institute press release: “If human growth would accelerate at the same rate, we would weigh half a ton by middle age and well over a ton at retirement.”

That’s a lot of growth!

And it has some important implications for climate change mitigation. As the older trees continue to grow, they are rate of carbon sequestration also increases, meaning the part they play in forests’ role as carbon sinks may be even more significant than previously thought.

So, if the wise owl couldn’t convince you and the adorable opossum couldn’t melt your heart, then perhaps our climate can warm you up to the importance of old growth in our forests. We must respect our elders.

American Forests has worked to protect old growth forests in areas such as Alaska’s Tongass National Forest. Join us in protecting and restoring forests of all ages.