ForSite | Nutrient exchanges | Biomass Harvesting
Nutrients accumulate in living trees as they grow. Some are removed from the site when stems are harvested as timber. Larger amounts of nutrients will be removed if branches and needles are harvested.Nutrient pools in harvestable biomass are calculated using nutrient concentrations of tissues, and mass. ForSite has developed a Specification for Estimating Biomass Fractions.
Nutrient pools in forest biomass
Sitka spruce, Yield Class 20, 35 years old, unthinned
Sitka spruce, Yield Class 20, 35 years old, unthinned
| Biomass | N | P | K | Ca | Mg | S | |
|---|---|---|---|---|---|---|---|
| t/ha | |||||||
| Stem wood | 171 | 107 | 7 | 67 | 87 | 14 | 71 |
| Stem bark | 18 | 66 | 8 | 39 | 77 | 9 | 10 |
| Branches | 33 | 145 | 13 | 53 | 86 | 17 | 20 |
| Needles | 15 | 217 | 20 | 101 | 58 | 14 | 20 |
![[image should be here]](images/BiomassHarvesting.jpg)
Biomass harvesting. Tree tops and branches are included in this material presented at roadside for chipping. This is a form of whole-tree harvest (WTH), and contrasts with conventional stem-only harvest (SOH) where only logs are removed from the forest.Page status: draft
