Thinning is harvesting with a constraint that clearfell does not have: most of the stand has to survive. The trees left standing carry the value of the next rotation, so damage inflicted now is a cost that appears years later on someone's balance sheet — usually the estate's, which is why thinning contracts specify residual damage thresholds and audit against them.
That single constraint reshapes the machine selection. Corridor width, machine width, boom reach and operator visibility matter more than raw production, and the largest harvester on the market is frequently the wrong answer because it cannot work the corridor spacing without damaging the crop. Restraint is the specification.
The economics are correspondingly tighter. Stems are smaller, so volume per hour is lower than clearfell at the same machine cost, and multi-tree handling — processing several small stems per cycle — is often what makes the job viable rather than a larger machine.
Every fleet produces at the rate of its slowest element and pays for all of them. This is where that element usually sits in this package.
Each one has an answer specific to your sites. A default taken from someone else's operation is where imbalance starts.
The smallest machine whose boom reaches the required stems from the corridor and whose head handles the stem sizes present. Medium wheeled harvesters dominate this work because they combine adequate reach with a width that the corridor spacing allows. Sizing up costs residual damage, not just capital.
10-15 tonnes is the common range because a larger forwarder's ground pressure and turning circle cause damage that outweighs the extra payload. As with the harvester, the constraint is the stand, not the load.
On small-stem thinning it usually pays for itself, because cycle time per stem dominates production when stems are small. Handling several stems per cycle is often the difference between a viable rate and an unviable one.
Through tyre or track selection and by working on brash mats where the residue allows. Soil compaction in a stand that will be worked again is a cost to the estate, and increasingly a contract condition rather than a preference.
The package above assumes a typical case. These are the departures that change the configuration rather than just the rate.
Very few contractors start at the full configuration, and the ones who do are usually carrying more capital than their contracted work supports.
Phase 1
A medium wheeled harvester with a small-stem head.
Phase 2
Harvester plus a 10-15 tonne forwarder sized to the same corridors.
Phase 3
A second thinning pair, or a larger machine for clearfell work between thinning contracts.
It produces more per hour in the stems it can reach and causes damage the contract will price back to you. A machine that cannot work the corridor spacing is not a faster thinning machine; it is a different job.
The head costs more and the production difference on small-stem work is large, because cycle time rather than cutting capacity limits output. The saving is recovered in the first contract on most small-stem stands.
Compaction in a stand that will be thinned again, and eventually clearfelled, is a cost transferred to the estate — and increasingly one that contracts return to the contractor.
Corridor width is productive area removed for the rest of the rotation. It is the most expensive way to solve a machine-selection problem.
The cut-to-length machine — fell, delimb, measure, buck and sort in one cycle.
Carries cut-to-length logs completely off the ground — payload × trips per hour is the whole economic model.
A machine in its own right — and the single most important specification decision in CTL.