Below is a technical, course-ready module you can directly integrate into your Sustainable Agarwood Plantation Management & Carbon Farming Course, farmer manuals, and investor due-diligence packs.
Climate, Soil, and Topography Requirements for Agarwood
(Aquilaria spp.)
1. Climate Requirements
Agarwood is a tropical forest species adapted to warm, humid, and seasonally wet environments.
A. Temperature
- Optimal range: 22–32 °C
- Tolerable range: 18–35 °C
- Growth slows below 18 °C
- Heat stress above 35 °C if combined with drought
👉 Stable warm temperatures support continuous cambial growth and resin response.
B. Rainfall
- Ideal annual rainfall: 1,800–3,500 mm
- Minimum viable: ~1,200 mm (with irrigation)
- Requires:
- Well-distributed rainfall
- Short dry season preferred (1–3 months)
⚠️ Prolonged drought reduces growth and resin induction success.
C. Humidity
- Relative humidity: 70–90%
- High humidity supports:
- Leaf health
- Fungal ecology linked to resin formation
- Extremely dry air suppresses resin response
D. Sunlight
- Young trees: partial shade (30–50%)
- Mature trees: full sun to light shade
- Excessive early exposure causes:
- Leaf scorch
- Stunted growth
👉 Natural forest or agroforestry shade is ideal.
2. Soil Requirements
A. Soil Texture
- Best: Loam, sandy loam, silty loam
- Acceptable: Light clay (if well-drained)
- Avoid:
- Heavy clay
- Compacted soils
Key requirement: Excellent drainage
B. Soil Depth
- Minimum effective depth: ≥1 meter
- Deep soils support:
- Strong taproot development
- Carbon storage
- Drought resilience
C. Soil pH
- Optimal pH: 5.5–6.8
- Tolerant range: 5.0–7.5
- Acidic soils acceptable if:
- Organic matter is high
- Aluminum toxicity is managed
D. Soil Fertility
- Moderate fertility preferred
- Excessive nitrogen causes:
- Rapid soft growth
- Lower resin quality
Key nutrients:
- Calcium (Ca) – cell wall strength
- Magnesium (Mg) – photosynthesis
- Micronutrients (Zn, B, Mn)
E. Soil Organic Matter (SOM)
- Target: ≥3%
- Benefits:
- Enhanced microbial activity
- Improved resin induction
- Higher soil carbon stocks
3. Topography Requirements
A. Elevation
- Optimal: 0–600 meters above sea level
- Tolerable: up to 800 m
- Higher elevations:
- Slower growth
- Cooler temperatures
B. Slope
- Ideal: 0–15% slope
- Acceptable: up to 25% with:
- Terracing
- Contour planting
Benefits of gentle slopes:
- Good drainage
- Reduced waterlogging
- Better root aeration
C. Flooding & Waterlogging
- Not flood-tolerant
- Prolonged waterlogging causes:
- Root rot
- Tree mortality
- Poor resin formation
👉 Avoid low-lying flood plains unless raised beds or drainage canals are installed.
4. Site Suitability Matrix (Quick Reference)
| Factor | Ideal | Marginal | Unsuitable |
|---|---|---|---|
| Temperature | 22–32 °C | 18–22 °C | <18 °C |
| Rainfall | 1,800–3,500 mm | 1,200–1,800 mm | <1,200 mm |
| Soil texture | Sandy loam | Light clay | Heavy clay |
| Drainage | Free-draining | Moderate | Poor |
| pH | 5.5–6.8 | 5.0–7.5 | <5.0 or >7.8 |
| Elevation | 0–600 m | 600–800 m | >800 m |
| Flood risk | None | Seasonal | Frequent |
5. Agroforestry Advantage for Site Optimization
Agarwood performs best in forest-like systems:
- Shade trees moderate temperature
- Litter improves soil carbon
- Companion species reduce erosion
- Enhanced microbial diversity
Recommended companions:
- Gliricidia sepium
- Erythrina variegata
- Sesbania grandiflora
6. Carbon Farming Implications
Good site selection leads to:
- Faster biomass accumulation
- Higher carbon sequestration rates
- Lower mortality → permanence
- Reduced project risk for carbon credits
Poor sites increase:
- Carbon reversal risk
- Financial loss
- Regulatory non-compliance
7. Practical Site Assessment Checklist (Field Use)
Before planting:
- ✅ Rainfall records (5–10 years)
- ✅ Soil texture & depth test
- ✅ Drainage test (24–48 hr infiltration)
- ✅ pH & organic matter analysis
- ✅ Slope & erosion risk assessment
- ✅ Flood history check
8. Key Learning Takeaways
By the end of this module, learners should be able to:
- Identify climate zones suitable for agarwood
- Evaluate soil profiles for plantation viability
- Assess topography risks
- Match site conditions to long-term carbon and resin productivity
Optional Next Steps I Can Prepare
- 📐 GIS-based site suitability map (Philippines / ASEAN)
- 🌱 Soil amendment & correction guide for marginal sites
- 📊 Carbon sequestration potential by site class
- 📘 Farmer-friendly site selection handbook
- 🧪 Soil testing SOP (field & lab)
Just tell me what you want next, and I’ll tailor it for Oud Academia / CI-ASASE and your plantation operations.