Acacia mangium: Growth, Allometry and Carbon Potential

Updated 2026-11-02 · 4 min read · By the akar.earth specialist team

Acacia mangium carbon sequestration: native range, pulp rotations, wood density, allometry, ARR role, and invasiveness and disease risks in Indonesia.

Acacia mangium sequesters carbon very fast in short rotations, which is why it became the backbone of Indonesian pulpwood plantations. For carbon projects it is a difficult choice: it is invasive outside its native range, prone to serious disease, and usually harvested every few years, so creditable stock is limited.

Identity and range

Acacia mangium is a nitrogen-fixing tree in the legume family, Fabaceae. In Indonesia it is called akasia or mangium; in English, mangium, brown salwood or black wattle (a name shared with other acacias).

Its native range covers Papua and parts of Maluku in eastern Indonesia, Papua New Guinea and northern Queensland in Australia. From the 1980s it was planted on a very large scale in industrial plantation forests (HTI) in Sumatra, notably Riau, Jambi and South Sumatra, and in Kalimantan, mostly on degraded mineral soils and, controversially, on drained peat. It was also used in reforestation of Imperata grassland.

Growth habit and rotation

Mangium is a fast-growing, light-demanding pioneer with large phyllodes (flattened leaf stalks that act as leaves). It tolerates acid, low-nutrient soils and suppresses grass once the canopy closes.

Pulpwood rotations are short, typically around 5 to 8 years. Sawlog rotations are longer but less common. Reported growth rates are high but vary widely with site, genetics and disease pressure, so we do not quote a single mean annual increment. Use local inventory data.

Wood density and biomass estimation

Reported basic density for A. mangium falls roughly between 0.40 and 0.60 g/cm³, varying with site, age and growth rate. Wood density is lower in young, fast-grown trees.

The default above-ground biomass model is Chave et al. 2014:

AGB (kg) = 0.0673 × (ρ × D² × H)^0.976

where ρ is wood density (g/cm³), D is DBH (cm) and H is height (m). Because the species was so widely planted, many species-specific equations have been published from plantations in Indonesia and Malaysia, mostly as power functions of DBH, some with height. These can be better than a generic model within their sampled range. Check the source age and diameter range before using one; see our allometric equations guide.

Convert biomass to carbon with the IPCC default 0.47, then to CO2 with 44/12. Add roots with a root-to-shoot ratio.

Carbon role in ARR and agroforestry

Mangium has been used to:

• Rehabilitate Imperata grassland by closing the canopy and suppressing fire-prone grass.
• Act as a nurse crop under which native species are later planted.

For credited ARR projects, the case is weak. Under VM0047, harvested systems are credited only up to the long-term average carbon stock, which is low for 5 to 8 year cycles. Many standards and buyers also look closely at the use of invasive non-native species and may require a risk assessment or exclude them. Where mangium is already on site, a project can plan its phased replacement with native species.

Co-benefits and livelihoods

Mangium fixes nitrogen, grows on poor soils and supplies pulpwood, fuelwood and small timber. Smallholder outgrower schemes linked to pulp mills provide income in parts of Sumatra and Kalimantan. Its flowers support honey production.

Risks and cautions

• Invasiveness. Mangium is listed as invasive in many tropical regions. Its hard-coated seeds persist in the soil for years and germinate after fire or disturbance. Outside Papua and Maluku it should be treated as non-native and invasive. Do not plant it next to natural forest or in conservation areas.
• Disease. Ganoderma root rot and Ceratocystis wilt caused severe losses in later rotations. Many plantation companies switched to Eucalyptus pellita on mineral soils as a result.
• Heart rot. Stems often develop heart rot, which reduces timber value.
• Fire. Large monocultures, especially on drained peat, carry high fire risk.
• Monoculture and peat. Plantations on drained peat cause large soil carbon losses that dwarf any tree carbon gain. See peat restoration rules.

Planning notes for project developers

• Existing stands count in the baseline. If mangium already grows on the site, its biomass belongs in the baseline, and only additional growth can be credited.
• Phased replacement. A common design keeps mangium as temporary cover, then underplants native species and removes the acacia in stages to avoid exposing soil and grass.
• Seed bank control. Expect mangium seedlings to germinate after any disturbance for years. Budget for weeding in monitoring plans.
• Peat exclusion. Do not include drained peat plantations in an ARR design without a peat rewetting plan; soil emissions would swamp tree gains.

Worked example

A mangium tree at pulp harvest with DBH 20 cm, height 18 m and wood density 0.50 g/cm³:

1. ρ × D² × H = 0.50 × 400 × 18 = 3,600
2. AGB = 0.0673 × 3,600^0.976 ≈ 199 kg
3. Carbon = 199 × 0.47 ≈ 94 kg C
4. CO2e = 94 × 44/12 ≈ 343 kg CO2e (above-ground only)

Run your own numbers in the tree CO2 calculator, and see species selection for ARR for native alternatives.