Here’s a detailed, course-ready module for your Sustainable Agarwood Plantation Management & Carbon Farming Course, manuals, and Oud Academia / CI-ASASE SOPs, focusing on estimating carbon stocks, growth curves, and sequestration rates in agarwood plantations.
Estimating Carbon Stocks, Growth Curves & Sequestration Rates in Agarwood
1. Introduction
Carbon accounting in agarwood plantations is essential for:
- Carbon credit projects
- ESG reporting
- Optimizing tree management for biomass and resin yield
Carbon stock estimation considers:
- Aboveground biomass (trunk, branches, leaves)
- Belowground biomass (roots)
- Soil organic carbon
- Deadwood / litter
Sequestration rate measures the annual carbon gain of a plantation.
2. Growth Curves of Aquilaria spp.
- Growth rate depends on species, age, soil, climate, and management
- Typical growth patterns:
| Age (yrs) | Height (m) | DBH (cm) | Notes |
|---|---|---|---|
| 1 | 0.5–1 | 1–2 | Nursery/establishment phase |
| 3 | 2–3 | 3–5 | Juvenile, first fertilizer response |
| 5 | 4–6 | 6–10 | Pre-resin induction maturity |
| 10 | 8–12 | 12–18 | Full biomass accumulation |
| 15 | 12–18 | 18–25 | Mature, peak carbon storage potential |
Diameter at breast height (DBH) is a key parameter for estimating biomass and carbon.
3. Biomass Estimation
A. Allometric Equations
- Biomass (kg) can be estimated using DBH and height:
Aboveground biomass (AGB):
[
AGB = 0.0673 \times (DBH^2 \times H)^{0.976}
]
(DBH in cm, H in meters)
Belowground biomass (roots):
[
BGB \approx 0.2 \times AGB
]
Total tree biomass:
[
Total = AGB + BGB
]
For resin-rich trees, adjust AGB by 5–15% for additional heartwood density.
B. Soil Carbon Estimation
- Soil carbon (0–30 cm) can be estimated using:
[
SOC = SoilC% \times BulkDensity \times Depth \times Area
] - Typical SOC: 1–3% in healthy agroforestry soils
4. Carbon Stock Calculation
- Carbon = 50% of dry biomass:
[
C_{tree} = 0.5 \times Total,Biomass
]
- Example (10-year-old tree):
- AGB = 120 kg
- BGB = 24 kg
- Total biomass = 144 kg → C ≈ 72 kg C/tree
5. Sequestration Rate
- Annual carbon sequestration rate = change in carbon stock per year
[
SequestrationRate = \frac{C_{final} – C_{initial}}{Years}
]
- Example:
- 5-year-old tree C = 40 kg
- 10-year-old tree C = 72 kg
- Sequestration rate = (72 – 40) / 5 = 6.4 kg C/tree/year
6. Plantation-Level Estimation
- Carbon stock per hectare:
[
C_{ha} = C_{tree} \times TreeDensity
] - Example: 250 trees/ha × 72 kg C/tree = 18,000 kg C/ha
- Sequestration rate per hectare:
[
6.4 \times 250 = 1,600 kg C/ha/year
]
Values vary with tree age, resin content, soil, spacing, and management practices.
7. Factors Affecting Carbon Sequestration
| Factor | Effect |
|---|---|
| Tree age | Older trees accumulate more biomass & resin → higher carbon |
| Resin induction | Denser heartwood → additional carbon per tree |
| Fertilization & irrigation | Promotes growth → higher sequestration rate |
| Agroforestry & intercropping | Nitrogen-fixing species improve soil carbon |
| Pruning & mulch | Returns carbon to soil; supports microbial biomass |
8. Monitoring & Record-Keeping
- Track DBH, height, resin content, tree age per tree
- Maintain soil carbon measurements annually or every 2–3 years
- Use digital tools or spreadsheets for carbon stock calculations
- Supports carbon credits, ESG reporting, and plantation valuation
9. Key Takeaways
- DBH, height, resin content, and tree density are central to estimating carbon stocks
- Aboveground, belowground, and soil carbon together represent total sequestration
- Annual sequestration rates enable carbon credit accounting and ESG compliance
- Integration with resin induction, pruning, and organic management enhances both productivity and carbon storage
Optional Next Deliverables
- 🌱 Step-by-step SOP for carbon stock estimation in agarwood plantations
- 📊 Growth curve and sequestration rate charts per age class
- 🧾 Monitoring logbook template: DBH, height, biomass, resin, soil carbon
- 📘 Farmer-friendly infographic: agarwood carbon stock & sequestration pathway
I can prepare a ready-to-use carbon stock & sequestration calculation template with growth curves and field logbook, tailored for Oud Academia / CI-ASASE plantations, next.
Do you want me to create that?