5 Things I Learned About Trees & CO2
After spending a summer in the forests and rural villages of Mexico, the Ellis family shares what they learned about their scientist dad and his work with carbon.
By Jes Ellis
We’ve been back in the U.S. for three weeks. The kids are back to school, I’m back in the classroom teaching, and Mexico already feels like a distant dream. This summer of “chasing carbon” has been an amazing experience for our family on many levels. We had fun, were challenged and were able to get a better sense of Papa’s “day job,” as promised.
Our children returned home with many lessons about the world and a strong sense of what their father does as a forest carbon scientist for The Nature Conservancy. Along the way we picked up more than a few facts about trees and carbon, some that I can even share with my students:
1. Estimating the amount of carbon stored in a forest can be as simple as hugging a tree (or more accurately by measuring its diameter at breast height with a tape measure). The biomass, or living matter, of a tree is about half carbon by weight, and based on tree measurements from around the world, researchers have devised an equation to measure carbon using trunk diameter. So my husband, Peter, being a rather tall guy, could effectively hug a tree about 5 1/2 feet around (21 inches in diameter). If we assume this tree is more or less average shape, height, and density for the tropics, we can estimate that it contains 3 metric tonnes of carbon locked up in its wood tissue (Chave et. al. 2005).
2. One of the highlights of our trip was visiting the Largest Tree in Latin America (El Tule) in Oaxaca. At 190 feet in diameter, it would take 26 men of Peter’s size to hug it, and it contains 636 metric tons of carbon. If it were chopped down tomorrow, it would eventually emit the carbon equivalent of 5000 barrels of crude oil (EPA 2012).
3. On average, trees in tropical forests hold about 50 percent more carbon per hectare than trees outside the tropics (Houghton 2005).
4. Carbon dioxide doesn’t only come from the burning of fossil fuels or forests. Dead trees emit carbon dioxide as they decay. In the tropics, rates of decay are much faster, so that most of the carbon in a tree (84 percent) has been emitted into the atmosphere after 10 years (Chambers et. al. 2000).
5. If deforestation stopped tomorrow, forests have the potential to offset about 1/3 of the total human-caused carbon emissions occurring today. (Pan et. al. 2011)
More than collecting facts, this summer we collected memories. One highlight was the day when we shadowed Peter on a site visit to a sustainable coffee plantation in the mountains of Chiapas. Jasper and Josie piled into the back of the pick-up truck with us, thrilled to be bouncing along the dirt roads in the open air, giddy with the anticipation of being able to “touch the clouds” when we got up into the cloud forest.
When we reached our destination: a small coffee grower’s plantation called Buena Vista, the vista was more than buena. It was maravillosa. The entire valley stretched out below us, mountains all around shrouded in afternoon rain clouds, the Triunfo Reserve to the south. Peter wanted to meet Don Ciro, age 84, and his son (also named Ciro), who is managing the plantation.
After a lunch of ingredients grown on the farm, Peter pulled out his computer to show the family his map of the carbon density of the forest near the plantation. I was skeptical that the Don Ciros would be able to make sense of the Rorschach-like fluorescent images Peter was describing, but they were riveted. With his limited but improving Spanish, Peter explained the potential to increase carbon stocks on their own land, emphasizing what an important resource they have at their fingertips - in other words, value beyond the fruits that they sow. Don Ciro and son did not seem to need convincing.
While we explored the terraced hillsides of the coffee plantation with the farmer’s granddaughter, Peter climbed to about 2,000 meters behind the main house with his team, cutting a path through the underbrush with a machete. When they reached the peak they were in an old oak forest of towering trees which had likely never been harvested by humans. The craggy, broad trunks supported high limbs covered with dangling bryophytes. Peter estimated the forest to be easily over 150 years old, and the carbon stocks at an impressive 200 tons per hectare.
We headed back down the mountain, exhausted and satisfied. We had climbed the mountain with Papa and spent a day in the field. Whether or not Jasper and Josie remember our time at Buena Vista in 20 years, this summer they saw what carbon looks like up close, and developed a greater appreciation for the challenges of accounting for it. Or at least I did. Jasper and Josie developed an appreciation for limes and chile, and iguanas and hummingbirds. But even that felt like enough. For now.
Jes Ellis is a teacher at Two Rivers Public Charter School in Washington, DC.
This post is adapted from a series of blogs on Planet Change authored by Jes & Peter Ellis, a Forest Carbon Scientist for The Nature Conservancy. Opinions expressed here are the personal opinions of the authors and do not necessarily reflect the views of The Nature Conservancy.
Photos courtesy of Jes & Peter Ellis