Replant.ca Environmental

Carbon Sequestration is the process of capturing atmospheric carbon dioxide (CO₂) for long-term storage. It is typically used as a tool to lessen greenhouse gases (GHG's) in the atmosphere, in order to defer climate change. Carbon sequestration can occur by two means: Terrestrial or geologic. Geologic sequestration involves capturing CO₂ at industrial sites and then storing it permanently in deep geological sub-surface reservoirs. Replant.ca Environmental is focused upon terrestrial sequestration.

Terrestrial (Biological) Sequestration

Terrestrial sequestration is the process of capturing carbon dioxide (CO₂) from the atmosphere and storing it in the stems and roots of plants and surrounding soil. Through photosynthesis, plants absorb CO₂ from the atmosphere. They then use that carbon as an organic energy source to produce carbohydrates (C₆H₁₂0₆) and in turn release oxygen (O₂). The balanced equation is as follows: 6CO₂ + 6H₂O goes to C₆H₁₂O₆ + 6O₂. Terrestrial sequestration land management practices are used to optimize the amount of CO₂ absorbed in plants and soil. Typically, trees with larger trunks, greater heights, and denser wood fibre are capable of sequestering more CO₂.

Benefits of terrestrial storage include: improved soil and water quality, reduced erosion, reduced evaporative water loss, reduced pest problems, overall ecosystem improvement, and the reduction of GHG's in the surrounding atmosphere.

Trees also remove other harmful atmospheric chemicals and pollutants, such as: Sulfur dioxide (SO₂), ozone (O₃), nitrogen oxides (NO_x), and particulates. All of these chemicals are produced from fossil fuel exhaust or burning coal.

Carbon Sequestration Measurements

Many factors are involved in determining the amount of CO₂ that a forest can sequester. Factors involved include: Abundance and variety of the species in the forest, the age of the forest, forest biodiversity, the density of the forest, soil quality, and forest management practices. Typically, managed forests sequester more CO₂ than unmanaged forests. Certain land management practices can be put into play to improve sequestering abilities, such as thinning, brushing, and pruning treatments. These treatments ultimately improve the DBH (diameter at breast height), height, crown volume, and overall fiber volume of individual trees within the stand.

For an average red pine tree, a tree before the age of ten years will sequester approximately 4.9 kg of CO₂ per year. For a longer time horizon, after reaching approximately ten years of age, an average tree is estimated to absorb an average of 21.8 kg of CO₂ in a year. This change ramps up with age, rather than being a sudden shift at ten years. The increase in sequestered CO₂ continues until the tree reaches the typical age of maturity, at which point it levels off.

At 40 years, it is possible for a typical average-sized tree to have sequestered 712 kg of CO₂ (or approximately 0.712 metric tons).

At 100 years, it is possible for that same tree to have sequestered approximately 2,012 kg of CO₂ (or slightly over two metric tons).

For a stand of just 10,000 new trees, the plantation will eventually capture more than twenty thousand metric tons of CO2 at maturity!

Species Diversity

Typically, a properly managed demonstration forest will not be cultivated as a monoculture. The presence of a variety of mixed species is beneficial to a forest. Biodiversity is advantageous for animal habitat, recreational value, insect/pest/disease mitigation, and stand resilience.

Replant.ca Environmental works with a wide variety of coniferous and deciduous species in our various management projects. The three main species used to target a healthy forest and maximize long term CO₂ sequestration on eastern Canadian projects are Eastern Hemlock, White Pine, and Red Spruce, with a mix of half a dozen hardwood species including birches, maples, and oaks. These species are favoured due to their dominant role in the forests of Eastern Canada. Different species (lodgepole pine, white spruce) are often favored in projects in central and western Canada, although the local environmental conditions will naturally be a determining factor. Lesser volumes of cedars, balsam fir, black spruce, Jack pine, larches, and a handful of additional deciduous species are also utilized in various locations throughout Canada.

Incidentally, our organization is often seeking land on which we can build additional carbon capture projects.

Here is a PDF pamphlet produced by our VP Research, Karla Sewell:

www.replant-environmental.ca/docs/pamphlet_carbon_capture.pdf

Here are additional resources which are a good starting point for additional research:

www.nrcan.gc.ca/climate-change/impacts-adaptations/climate-change-impacts-forests/forest-carbon/13085

www.nationalgeographic.com/environment/2019/01/carbon-capture-trees-atmosphere-climate-change

urbanforestrynetwork.org/benefits/air%20quality.htm

www.carbonbrief.org/planting-a-mix-of-tree-species-could-double-forest-carbon-storage

We encourage you to visit our 2023 Progress page next, to see what we're currently working on!