Pulp Fibre Sources
Pulp is made from cellulose fibre, and the fibre source shapes everything downstream: strength, smoothness, cost, and where in the world a mill can operate. This page looks at fibre as pulp furnish, the raw material side of pulp manufacture, where the industry draws on four main sources: softwood, hardwood, non-wood plants, and recovered paper. For the species themselves, the forest zones they grow in and how long they take to reach harvest, see forests; for the same species as sawlog raw material, see sawmilling.
Fibre sources at a glance
| Fibre class | Source | Fibre length | Key regions |
|---|---|---|---|
| Softwood | Boreal spruce and pine | 2.45 to 4.26 mm | Nordics, Canada, Russia |
| Softwood | Southern pine (loblolly) | 2.2 to 2.7 mm | US South |
| Hardwood | Northern birch and aspen | 0.9 to 1.1 mm | Nordics, Baltics, Canada |
| Hardwood | Eucalyptus | 0.66 to 0.88 mm | Brazil, Uruguay, Chile, Iberia |
| Hardwood | Acacia | 0.60 to 0.79 mm | Indonesia, Vietnam |
| Non-wood | Straw, bagasse, bamboo | Varies | India, China, SE Asia |
| Recovered | Recovered paper | Shortens with each cycle | Everywhere paper is consumed |
Two levels are deliberately mixed. Softwood and hardwood is the property split that decides what a pulp can do; within each, the rows are the commercially distinct baskets, which is why boreal spruce and southern pine sit apart despite both being softwood. They differ by a millimetre of fibre and by the markets they serve.
Fibre lengths are length-weighted pulp values unless noted: boreal softwood is an arithmetic mean on tracheids in wood, southern pine is plantation whole trees (outerwood alone reaches 3.1 mm), northern hardwood is commercial bleached birch kraft. Arithmetic means on wood run higher than pulp values, at 0.95 to 1.11 mm for eucalyptus and 0.96 to 1.06 mm for acacia. An arithmetic mean counts every fragment equally so fines pull it down, while a length-weighted mean weights long fibres more heavily, and comparing one against the other is the classic way to overstate a fibre by a millimetre. Rotation lengths by species and region are on forests.
Softwood
Softwood (conifer) fibres are long, which is what makes them the backbone of strong papers: a long fibre forms more bonds along its length, so the sheet resists tearing and pulling apart. That is why softwood carries packaging grades, gives tissue its wet strength, and is blended into printing paper purely as reinforcement. Key species include spruce, pine, fir, hemlock, Douglas fir and larch. The world's softwood pulp capacity is concentrated in two very different forest belts: the slow-grown boreal and temperate forests of the Nordics, Canada and Russia, and the fast-grown subtropical plantation pine of the southern United States. See softwood kraft mills on the map.
Hardwood
Hardwood fibres are short and fine, so they pack into a dense, even sheet with a smooth surface and high opacity. That is what printing and writing papers need, and it is what gives tissue its softness. Commercial species range from birch and aspen in the north to eucalyptus and acacia in fast-growing plantation regions. Eucalyptus in Brazil, Uruguay and Iberia, and acacia in Southeast Asia, have made the southern hemisphere the growth engine of hardwood pulp. forests
Most paper grades blend the two: softwood for strength, hardwood for surface and formation.
Non-wood fibre
Agricultural residues and purpose-grown plants supply pulp where wood is scarce or regulation favours residues: wheat and rice straw, bagasse (sugarcane residue), bamboo, kenaf and hemp. Non-wood pulping is significant in India and parts of Asia. Fibre quality varies widely, and collection logistics limit mill size.
Recovered fibre
Recovered paper is the largest single fibre source for the global paper industry by volume, supplying a median 46 % of European pulp furnish. Old corrugated containers (OCC) feed recycled packaging grades; sorted office paper and old newsprint feed deinked grades.
Fibres shorten with each cycle, and the widely quoted "five to seven times" is a rule of thumb about when fibre becomes too short to use, not a measurement. Two better-defined numbers exist and say different things: the measured average actual reuse of a paper fibre is about 3.5 times in Europe and 2.5 times worldwide (2022), while laboratory studies reach 15 to 25 cycles before properties plateau. Either way the system continuously needs an inflow of virgin fibre. Mills running purely on recovered paper consume no roundwood, which is why WoodComp tracks them separately from wood-consuming mills. methodology
Frequently asked questions
Why is softwood pulp stronger than hardwood pulp?
Fibre length. Boreal softwood tracheids measure roughly 2.5 to 4.3 mm in the wood against 0.9 to 1.1 mm for commercial birch pulp, and longer fibres form more bonds per fibre, giving the sheet higher tear and tensile strength.
Why has eucalyptus become so dominant in pulp?
Growth rate. Plantation eucalyptus in Brazil reaches harvest in well under a decade and grows several times more volume per hectare and year than boreal forest, which takes closer to a century to reach final felling, giving southern-hemisphere mills a structural cost advantage in hardwood pulp. The growth and rotation figures are on forests.
How many times can paper fibre be recycled?
It depends what you measure. The often-quoted five to seven times is a rule of thumb about fibre becoming too short to use. Measured average actual reuse is about 3.5 times in Europe and 2.5 worldwide, while laboratory studies reach 15 to 25 cycles before properties plateau. All three framings agree the system depends on an inflow of virgin fibre.
Do recycled-paper mills compete for wood?
No. They run on recovered paper alone, unlike the 1147 wood-consuming mills in the database.
Sources10 references
Fibre length
- Fabisiak, E., Fabisiak, B., Krauss, A. 2020, radial variation in tracheid length in dominant trees (spruce and pine). Arithmetic mean on macerated wood
- Dahlen, J., Nabavi, M., Auty, D., Schimleck, L., Eberhardt, T.L. 2021, models for within-tree tracheid length in loblolly plantations. **Length-weighted** mean
- UPM Pulp, tekniskt datablad *UPM Betula ECF Bleached Birch Kraft Pulp* (Pietarsaari mill). Commercial mill value, length-weighted
- Gominho, J. et al., eucalyptus kraft pulp. Length-weighted fibre length (Morfi analyser)
- TAPPI T 271 om-18, *Fiber Length of Pulp and Paper by Automated Optical Analyzer*, the method standard for length-weighted means. Paywalled, so the formulae were not independently verified
Growth and rotation
- IBA, *Annual Report 2025*, Brazilian eucalyptus 34.4 m³/ha/yr over bark, rotation 6 to 8 years
- SLU Riksskogstaxeringen, *Skogsdata 2025*, Swedish growth 4.9 m³sk/ha/yr, realised final felling age 100 years
Recovered fibre
- FAO/ITTO/UNECE 2020, *Forest Product Conversion Factors*, chapter 7. Recovered fibre share of European pulp furnish
- US EPA, *Paper Making and Recycling* (archived). Source of the "five to seven times" rule of thumb
- Two Sides UK, *Paper Recovery and Recycling*. Measured actual reuse 3.5 times in Europe and 2.5 worldwide (2022); laboratory studies reach 15 to 25 cycles