By Calvin Norman and Melissa Kreye
In conversations about forests and carbon, the term "sequestration" is often used—sometimes inappropriately. Trees both sequester and store carbon, but these are different activities. To help improve discussions about carbon and its value in a market context, this article will explain the difference between carbon sequestration and carbon storage.
Sequestration vs. Storage
Carbon Sequestration
Sequestration is the act of capturing a substance; in this case, it is capturing carbon molecules from the air. Carbon sequestration is the process of removing carbon dioxide–one of the leading greenhouse gases—from the atmosphere, thereby reducing the total concentration. Living trees sequester carbon through photosynthesis. Using light, leaves create sugar by capturing carbon dioxide molecules and combining them with water molecules. Oxygen is released into the atmosphere as a byproduct of this process. Plants only sequester carbon when they are alive. The sequestration occurring in forests is part of the carbon cycle that helps regulate the climate. In fact, the environmental service traded in carbon markets is the sequestration process (not carbon storage). Increasing the carbon sequestration services provided by trees helps offset additional carbon released through the use of fossil fuels. Trees are ideal for carbon sequestration because of their large size, environmental flexibility, and photosynthetic efficacy. Additionally, the practice of forest management is well established and can help enhance the sequestration services by strategically increasing primary production or tree growth.
Carbon Storage
Another important term is storage. This is the act of retaining carbon in a solid form which keeps it out of the atmosphere for a long time (50 years or more). Carbon storage is a key but often overlooked function of trees and forests. All life on earth is made of carbon which means it is keeping it out of the atmosphere, but that carbon is released when organisms die. Organisms that decompose quickly after death, thereby releasing CO2, are poor at storing carbon for long periods. Trees are good at holding onto carbon for long periods, even after the tree stops growing. Roughly 50% of the dry mass of a tree is carbon, much of which is stored in the wood fibers. Wood molecules, like lignin, are so difficult to decompose that only a handful of fungi can break them down. Wood products, like furniture and building material, are protected from rot and have the potential to extend the storage of carbon. The difficulty in breaking down woody material is also why there is so much coal in Pennsylvania. Coal is made from ancient forests and plants that didn’t fully decompose because they were covered by dirt, water, and rocks. After a few millions of years of heat and pressure, the dead trees and plants were transformed into coal.
Source : psu.edu