Editor’s Note: Here’s what the Ellis family did on their summer vacation: travel to Mexico with Dad Peter Ellis, a forest carbon scientist for The Nature Conservancy, enjoy limes and sample merengues, learn how trees and mangroves store carbon in their roots and branches, explore ruins and forest streams, return to the U.S., and move into a new home. Whew! In the final posts of their series Chasing Carbon, Jes Ellis shares what her family learned in the forests and rural villages of Mexico.
We’ve been back in the U.S. for more than a month. 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.”
We also learned a ton. Among the lessons worthy of sharing with my students is this one: 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).
While we spent far too little time physically in the field with my husband Peter, we found ourselves much closer to his work than ever before. Each evening we were able to hear about details of his work that are usually lost in the hectic dinner conversations at home.
For one thing, we learned about several ways that scientists estimate the amount of carbon stored in a forest (trees act like sponges that soak in carbon dioxide from the air). One way to measure a forest’s stored carbon is 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 measurements of trees around the world, researchers have devised an equation to measure carbon using trunk diameter. So Peter, being a rather tall guy, could effectively hug a tree about 5 1/2 feet in circumference (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 tons of carbon locked up in its wood tissue (Chave et. al. 2005).
During our travels, we visited 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).
My children also heard about one of the most important tools of a carbon scientist: a relascope. This simple, small rectangular piece of glass is no bigger than Peter’s thumb and hangs from a string around the neck or a belt loop for safe keeping.
Peter showed the farmers how to look through the prism at any tree and determine if a tree is big enough to be counted for a carbon survey. If the trunk of the tree is wide enough so that the image of the tree overlaps in the prism, then it is big enough to be counted. If it is so narrow that the trunk does not appear to overlap in the prism, it is not counted.
Another type of “relascope” is a thin aluminum plate about the length and width of two fingers, with a rectangular sighting hole cut in the middle. Using perspective, a forester, farmer or carbon scientist can hold the plate at chain’s length and peer through at his trees. He or she rotates 360 degrees and counts every tree that exceeds the width in the cut-out, multiplies by a set factor (for example, 20 tons per hectare) to determine the total tons of carbon for that tree width on the plot. “It’s where geometry makes magic,” claims Peter.
After this brief lesson on counting carbon, one of the farmers cut a length of vine from a nearby tree and picked up an oak leaf off the ground. He punched out a small square from the center of the leaf, attached it to the vine, and held it up at arm’s length. An instant all-natural relascope!
Stay tuned to Planet Change this week for the final post in the Ellis family Chasing Carbon series.
Jes Ellis is a teacher at Two Rivers Public Charter School in Washington, DC. This post is part of a series of blogs authored by Jes & Peter Ellis, a Forest Carbon Scientist for The Nature Conservancy. Opinions expressed here are the personal opinions of the author and do not necessarily reflect the views of The Nature Conservancy.
Featured photo by: Miguel Mendez Lopez of Comon Yap Nop Tik Cooperative (Measuring forest carbon with a relascope).
Remaining photos courtesy of Jes & Peter Ellis: Photo 2: (Jasper in the field with his Dad, Peter Ellis.)
Photo 3: (Budding scientist Josie Ellis uses her own method to gauge the weight of a log.)
Photo 4: (Jes Ellis checks out the view of the forest from an observation tower.)
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