Ask how much carbon a restoration project will sequester and the conversation usually goes to species and growth rates. The more consequential decision is made earlier and thought about less: how many trees go in, how far apart, and in what mix.
Density Is a Trade, Not a Maximum
More stems per hectare means more carbon early. It also means competition sooner, and competition slows individual growth and raises mortality.
| Density | Early accumulation | Later behaviour |
|---|---|---|
| High | Fast — many small stems | Competition, self-thinning, mortality |
| Moderate | Slower start | Sustained individual growth |
| Low | Slowest | Under-uses the site |
The carbon curve for a dense planting rises steeply then flattens as competition sets in. A moderate planting climbs more slowly and keeps climbing. Which is better depends entirely on the crediting period and on whether the project needs early issuance for cash flow.
That is a financing decision disguised as a silvicultural one, and it deserves to be made explicitly.
Mixed Species Change the Arithmetic
A mixed planting is not a weighted average of its species. Fast-growing species occupy the canopy early and may suppress slower ones; nitrogen-fixers can improve growth for neighbours; species with different rooting depths compete less than species with the same.
The ex-ante model has to represent those interactions or it will overstate the result, because modelling each species independently and summing assumes they do not affect each other, which is precisely wrong in a mixed stand.
What This Means for Sampling Later
Design decisions made now determine the stratification you will need in ten years.
A uniform planting across a uniform site can be sampled simply. A mosaic of densities and species mixes, planted in different years, is several strata and if the planting records do not identify which block is which, the stratification cannot be reconstructed.
Record the design as implemented, not as planned. Field realities change spacing and species mix, and the difference between the two is exactly what a verifier will find in the plots.
The Decision Worth Writing Down
For each block: species, spacing, planting date, and why. That last field is the one nobody fills in and the one that explains everything else a decade later, when the people who made the decision have moved on.
Track what happens after planting
Survival rate is the assumption that quietly decides a restoration forecast. TREEO Dashboard monitors planting cycles and tracks survival so the number you report is the number you measured.
