About the Reforestation Sequestration
This calculator estimates the total carbon dioxide sequestered by a tree-planting project over a chosen number of years, accounting for the fact that not every planted tree survives to maturity. It is intended for anyone evaluating a reforestation effort's climate impact, whether planning a project or assessing a carbon offset claim tied to one.
How It Works
You enter the number of trees planted, the number of years of growth being evaluated, and an expected survival rate as a percentage. The calculator first reduces the planted tree count by the survival rate to get surviving trees, then multiplies that figure by a fixed per-tree annual sequestration rate and by the number of years to get total sequestered CO2.
Formula & Methodology
The 0.0218 metric tons per tree per year figure is the same commonly cited mature urban tree absorption rate used elsewhere on the site, applied here as a flat annual rate across the full growth period rather than as a rate that changes with tree age. This makes the model a straight-line average: it assumes every surviving tree, from its first year to its last, absorbs the same amount of carbon annually, when real trees typically sequester more per year as they mature.
Examples
500 trees over 20 years
With the default inputs of 500 trees planted, 80% survival, and 20 years of growth, surviving trees come to 500 x 0.8 = 400, and total sequestration works out to 400 x 0.0218 x 20 = 174.4 metric tons of CO2.
A larger, shorter-term project
Planting 2,000 trees with a 65% survival rate over 10 years gives 2,000 x 0.65 = 1,300 surviving trees, and total sequestration of 1,300 x 0.0218 x 10 = 283.4 metric tons of CO2, more total carbon despite fewer years, due to the larger planted count.
Advantages
- Builds tree survival directly into the estimate instead of crediting a project for every tree planted regardless of outcome
- Lets project planners test how changing survival assumptions or the evaluation timeframe shifts the total sequestration figure
- Uses the same per-tree rate as the site's standalone tree offset calculator, keeping the two tools directly comparable
Common Mistakes
- Reporting a project's impact based on trees planted rather than trees expected to survive to maturity, which can overstate sequestration by 10-40% depending on the survival rate used
- Treating the straight-line output as a precise year-by-year growth model rather than the simplified long-term average it actually represents
- Applying survival rates or per-tree sequestration figures from a very different climate or species mix than the one actually being planted
Edge Cases to Watch For
- Survival rate is applied once, upfront, to the full tree count rather than as a gradual mortality curve occurring across the growth years, which simplifies but doesn't fully capture how reforestation losses actually unfold over time.
- The linear per-year rate doesn't reflect that young saplings sequester less carbon annually than mature trees, so early-year totals in a real project would tend to run below this estimate and later-year totals above it.
- The same fixed rate is applied regardless of species or climate, even though actual sequestration rates vary significantly by tree type, planting density, and growing conditions.
Common Use Cases
- Nonprofit or community reforestation project planners preparing impact estimates for donors or reports
- Individuals evaluating the carbon claims behind a tree-planting offset purchase before buying
- Students or researchers doing a first-pass estimate of a reforestation scenario's climate contribution