Material Assumptions (typical values)
The following assumptions represent commonly used average values for woody biomass materials such as bark and mulch:
Average dry matter content: 90%
Carbon fraction of dry matter: 33–36% (range)
Carbon to CO₂ conversion factor: 3.67
Carbon Storage Calculation (per tonne of material)
Step 1 – Dry matter per tonne:
1,000 kg × 90% = 900 kg dry matter
Step 2 – Carbon content of dry matter (range):
Low case: 900 kg × 33% = 297 kg carbon
High case: 900 kg × 36% = 324 kg carbon
Step 3 – Convert carbon to CO₂ equivalent:
Low case: 297 kg C × 3.67 = 1,090 kg CO₂
High case: 324 kg C × 3.67 = 1,189 kg CO₂
Rounded and presented as a typical indicative range.
Indicative Carbon Storage Result
Indicative carbon storage for ornamental bark & mulch:
Approximately 1,100–1,200 kg CO₂ per tonne
How this figure should be interpreted
This figure represents the amount of atmospheric carbon dioxide captured during tree growth and retained within woody biomass while the material remains in use.
It does not represent permanent sequestration, a carbon offset, or net lifecycle emissions. The duration of storage depends on how and where the material is applied and managed.
Emissions and lifestyle considerations
Emissions associated with harvesting, processing, transport, installation and end-of-life treatment are not included in this calculation and must be assessed separately when considering overall environmental impact.
Product-specific notes
Carbon content varies with species, bark-to-wood ratio, moisture content and processing. Storage duration is influenced by particle size, application depth, site conditions and maintenance practices.
Reference sources
IPCC (2019) – Refinement to the 2006 Guidelines for National Greenhouse Gas Inventories (biomass carbon fraction guidance; C→CO₂ factor)
FAO – Forestry and biomass carbon publications (woody biomass carbon context)
UK DEFRA – Greenhouse Gas reporting guidance (context for carbon communication)
Peer-reviewed literature on woody biomass carbon content and decomposition/stability in landscape applications
This document is intended to support informed discussion and responsible material selection.
Good design begins with responsible decisions.
Future landscapes will be judged by today’s actions.