What do field staff need to record?
Start a new survey, enter the forest area in hectares, and set the quadrat length and width in metres. Select the active quadrat before adding trees. For each tree, record its label, species and the circumference of every separate stem in centimetres. Confirm the quadrat’s latitude and longitude, whether obtained with the device’s location service or entered manually.
The app links trees to their quadrat and includes its coordinates in the CSV export. Use consistent tree and quadrat labels when returning for repeat measurements. Species photographs support identification; they do not replace confirmation by someone familiar with local mangroves.
How is DBH calculated from circumference?
DBH means diameter at breast height. Enter the measured circumference, not the diameter, into the calculator’s stem field. The app uses the circular-stem relationship:
DBH (cm) = circumference (cm) ÷ π
For example, a circumference of 60 cm gives a DBH of approximately 19.10 cm. Keep the tape perpendicular to the stem. Follow your sampling protocol for measurement height and record any departure caused by buttresses, prop roots or irregular stems. The measurement point must suit the selected biomass equation and remain consistent on later visits.
How does the calculator handle multiple stems?
Use “+ stem” to enter each stem’s circumference separately. The app converts each one to diameter, calculates its biomass, then adds the stem biomass estimates. Do not enter the combined circumference of the whole group.
Equivalent DBH = √(D₁² + D₂² + … + Dₙ²)
The square-root formula preserves combined basal area. For two stems with diameters of 10 cm and 20 cm, equivalent DBH is about 22.36 cm. It is an inventory summary, not the diameter used by this app to estimate the group’s biomass. Field protocols and allometric model applicability still need checking for unusual growth forms.
Species, wood density and carbon estimates
The symbol ρ is wood density in g/cm³. Selecting a species supplies a reference value that can be replaced with a justified local value. This lookup is not an additional tape measurement. The IPCC coastal wetlands guidance, Annexes 4A.2–4A.3, discusses mangrove allometry and lists species wood densities.
The calculator implements these equations for each stem, with D in centimetres and biomass in kilograms of dry matter:
Above-ground biomass = 0.251 × ρ × D2.46
Below-ground biomass = 0.199 × ρ0.899 × D2.22
It adds the two biomass pools, applies a carbon fraction of 0.47, and converts carbon to the corresponding mass of CO₂ using 44/12. These are the app’s current assumptions, not site-specific laboratory results. Confirm model suitability before using an estimate in research reporting.
The species graph describes the living-biomass carbon represented by the trees you entered. A species’ percentage depends on those trees’ sizes and abundance; it is not a universal annual sequestration ratio.
Can DBH determine soil organic carbon?
No. The optional SOC calculation needs separate soil bulk density, sampled depth and organic carbon percentage. Enter measured or otherwise justified soil inputs; the displayed defaults are not measurements of your forest.
SOC (Mg C/ha) = bulk density (g/cm³) × depth (cm) × [carbon (%) ÷ 100] × 100
This simple calculation assumes the inputs represent the sampled layer and does not separately model coarse fragments or multiple horizons. Without suitable soil data, leave SOC disabled and describe the result as a living-biomass estimate, not a complete ecosystem inventory.
How are dead wood and litter included?
They are optional, separately sampled carbon pools—not values inferred from living-tree DBH. In each quadrat, enter the dry biomass of standing and downed dead wood across the full quadrat. Field teams must estimate that dry mass using an appropriate inventory method, such as measured volume and decay-adjusted wood density. Do not count a dead tree again as a living tree.
For litter, collect material from known-area subplots within each quadrat, determine the combined oven-dry mass, and enter both that mass and the total sampled subplot area. A blank means not sampled; enter zero if the pool was checked and absent. The calculator pools the measured mass and area across completed quadrats rather than treating missing observations as zero.
Pool stock (Mg C/ha) = [Σ dry mass (kg) ÷ Σ sampled area (m²)] × carbon fraction × 10
The initial carbon fractions are 0.50 for dead wood and 0.45 for mangrove litter, following the Coastal Blue Carbon field manual. Replace them with locally measured fractions when available. If only some quadrats are sampled, the displayed stock is based on those quadrats alone and may not represent the forest. The app does not automatically generate a five-pool inventory from tree diameters.
Quadrat size and whole-forest estimates
The app uses a common length and width for all quadrats in the survey. Total sampled area is length × width × number of quadrats; divide square metres by 10,000 to obtain hectares. A 10 × 10 m quadrat covers 100 m², or 0.01 ha.
Sample totals are converted to per-hectare estimates and scaled to the entered forest area. This is an extrapolation, not a census. Plot presets and the 1% coverage display are planning aids, not universal international sampling standards. Your sampling design must address forest variation and the precision required for your study.
Storage is not an annual sequestration rate
A single inventory estimates a stock at one time. It cannot establish how much CO₂ a species removes each year or how many years a tree will keep absorbing it. Repeat inventories and an appropriate accounting method are needed to estimate change over time.
“Added capacity” in this app means the extra storage projected by the chosen annual removal factor, time horizon and area-change assumptions. It is a scenario, not a guaranteed forecast. The projection does not explicitly model mortality, storm damage, harvesting or soil-carbon loss.
Offline use, new sessions and private data
Open the calculator online first and allow its offline files, including species reference images, to finish downloading before leaving coverage. Installing saves the calculator for offline field use; other oceaospace pages remain part of the website. Location capture depends on device support, permissions and available positioning signals; manual latitude and longitude remain available.
A fresh opening starts without previous tree records. Active measurements and session archives stay in the current page’s memory, not a shared survey database. Download the CSV before closing or reloading: the app does not restore those records afterward. Keep exported files in storage controlled by your research team, particularly when they contain sensitive sampling locations.
References and responsible use
This guide explains the application; it is not an independently reviewed sampling protocol or a carbon-credit certification. oceaospace does not claim endorsement by IPCC, IUCN or UNFCCC.
- IPCC 2013 Wetlands Supplement, Chapter 4: Coastal Wetlands — inventory context, allometry and reference wood densities.
- Komiyama, Poungparn & Kato (2005): Common allometric equations for estimating the tree weight of mangroves — the allometric work referenced by the calculator.
- UNFCCC: REDD+ measurement, reporting and verification — formal results require reporting and verification against reference levels; a calculator output alone does not meet those requirements.
- IUCN/Blue Carbon Initiative: Coastal Blue Carbon field manual — field and laboratory approaches for dead wood and litter biomass and carbon fractions.