Big Trees, Carbon & Old Growth Comment Period
As GHCC’s Development Director, I spend most of my days communicating our organization’s work to our membership and securing funding sources that ensure GHCC can continue to protect, connect and restore this spectacular region. However, for the last several months I’ve had a mini-research project on my mind. Over the last several years, I’ve heard more and more about the concept of forests as a “carbon sink” and the importance of trees in the fight against climate change. Although the concept of a “sink” or “reservoir” is compelling in communications, I found myself wanting to have a deeper understanding of the carbon, forest, and climate relationship.
It was time to go back to the basics: I needed to remind myself just exactly why trees, and especially big trees, are one of our best agents in the fight against climate change. Here’s what I learned:
The Carbon Cycle + Its Role in Climate Change
The Earth holds a finite amount of carbon between its biosphere and the atmosphere. The carbon cycle is the process by which carbon molecules move between these two locations. On Earth, most carbon is stored in rocks and sediments (composed of dead organisms) and the rest is stored in the ocean and in living organisms (like forests!). When we talk about carbon “sinks” we’re talking about these places. Carbon is released back into the atmosphere through a variety of processes, including plant and animal respiration, fire, agriculture, and when humans burn fossil fuels.
Carbon is one of the greenhouse gasses – a phrase used to describe a number of gasses that trap some of the sun’s heat in Earth’s atmosphere and enable life on this planet. However, increasing amounts of greenhouse gasses, including carbon, are causing more heat to be trapped in the atmosphere. As a result, the Earth’s temperature is warming at an unprecedented rate.
Trees Capture & Store Carbon
Trees perform two key services related to carbon: they take it out of the air through photosynthesis, and they store it in their trunk, roots, and leaves throughout the duration of their lifetime. During photosynthesis, trees use energy from the sun to chemically combine carbon dioxide with hydrogen and oxygen from water to create sugar molecules. Carbon atoms then remain in the glucose and become the building blocks for the tree to grow. Leaves that fall from the tree also store a portion of their carbon in the soil as they decompose.
How does the age of a tree affect its ability to capture and store carbon? As trees age, they continuously increase their rate of growth. Thus, their capacity to capture and store carbon increases each year. While scientists used to believe that a tree’s rate of growth slowed with age, a ground-breaking 2014 Nature Article from an international team of researchers definitively showed that the rate of tree carbon accumulation increases continuously with tree size.
“While they are alive, large old trees play a disproportionately important role within a forest’s carbon dynamics. It is as if the star players on your favorite sports team were a bunch of 90-year-olds." – Adrian Das, USGS Co-Author
Trees Send Carbon Back to the Atmosphere…Eventually
The beauty of the relationship between trees and carbon is that trees naturally capture and store more carbon through photosynthesis than they release through respiration. But what happens to a tree’s carbon when it isn’t left to stand and grow old? Of course, any tree in this scenario would lose its carbon capturing abilities. But what about all that stored carbon? I looked into three different scenarios:
When a Tree Burns: When a tree burns in a wildfire, the carbon stored in it is released into the atmosphere. This is a natural process that is part of the carbon cycle. The amount of carbon that is released during combustion (burning) is debated. Previous research has indicated that tree’s release a majority of their carbon during combustion. However, new OSU research indicates that the tree’s – especially large trees – continue to store the majority of their carbon even after a wildfire.
When a Tree Decomposes: As a tree dies, it releases its carbon back into the atmosphere. Depending on the tree species, the amount and rate of release will vary over years and even decades. The leaves and other organic matter from the dead tree often become part of the soil’s carbon sink.
When a Tree is Cut Down for Forest Products: When a tree is cut down, the resulting forest products continue to store carbon. Especially in products that are long-lasting (think of a house vs. computer paper) the carbon molecules will stay in the wood for its lifetime or until it breaks down. But the process required to create these products is often energy and emissions intensive. In Oregon, the timber industry is actually the largest emitter of carbon, due to the fuel burned by logging equipment, the hauling of timber, milling, and wood burned during forestry activities (HCN). So while the resulting forest product may still store carbon, the process required to create the forest product isn’t saving us any emissions.
The Case for Big Trees
My research into the relationship between carbon, trees, and climate change provided me with the foundational science to understand why it's so important to protect big trees as climate change fighting agents. Here are some of the top reasons large, old growth trees should be protected as it relates to climate change:
Old trees accumulate (capture and store) carbon at a faster rate than young trees.
Any standing tree is always performing TWO services related to carbon sequestration – capture (photosynthesis) and storage (existing). As soon as a tree, and especially a large tree is cut, it loses half of its climate-change-fighting abilities!
In Eastern Oregon, less than 3% of trees on our National Forests are larger than 21” in diameter. It is absolutely critical that we protect these trees, as well as the next generation of old growth, so that our forests can continue to perform these key carbon services.
We have an opportunity to protect big trees across all of the country’s National Forests through the Biden Administration’s proposed old growth rule. This rule is still under development, and the current draft is heavy on management (i.e. logging) and light on protecting mature trees and recognizing the services these trees provide as is! As a result, it’s more important than ever to advocate for the enforceable protection of big trees so that we can safeguard their ability to capture and store vast amounts of carbon.
Will you join us in letting the Biden Administration know that we want ENFORCEABLE protections for mature and old-growth trees on our National Forests? In addition to providing a myriad of benefits to the ecosystem, old-growth trees are truly one of our best resources in the fight against climate change.
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