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What does pienuratekniikka mean?
Pienuratekniikka is Finnish for "narrow-trail technique" (pienura = small trail). It is a thinning method in which the first thinning is done with a compact forest machine along narrow trails spaced roughly 10 metres apart – without the permanent strip roads that remove productive growing area. The method is described in full on "What is pienuratekniikka?".
How wide are the trails?
Roughly 2.5–3 metres – the machine is 1.65 metres wide and fits between the crop trees, which stand 2.5–3 metres apart after first thinning. For comparison: in conventional Finnish harvesting, strip-road width on mineral soils is kept below 4.6 metres, with a planning guideline of at least 4.5 metres.
Are the trails still visible at the next thinning?
Often not. The narrow trails typically close over so completely that they can no longer be seen in the stand by the second thinning. Strip roads for larger machines are opened only at the second thinning – harvesting full-grown trees from the road lines in the process.
Can the second thinning be done with a full-size machine after pienuratekniikka?
Yes. The method does not commit the following harvests to anything: at the second thinning, a normal strip-road network is opened for whatever machinery does the work. Alternatively, some compact harvesters handle log-sized trees, so even the second thinning can be done with compact machinery.
Does a first thinning cost more with pienuratekniikka?
Expectedly yes – a smaller machine's harvesting productivity is likely lower than a full-size machine's. But the economic idea of the method is not the price of a single harvest; it is the whole rotation period: when no growing area is lost to strip roads, second-thinning yield and total output rise. Whether the gain covers the cost difference is currently being examined in research – no cost figures have been published yet.
What is the harvesting quality like?
A light machine and narrow trails leave remarkably little soil and root damage. According to preliminary research observations, the narrow trails did not significantly reduce the number of remaining trees. Harvesting quality is currently being measured in research whose results are collected on the Research page.
Does the method work in winter?
With limits. In periods of deep snow, smaller-wheeled machines struggle, as the harvester must advance through untouched snow. On the other hand, a light machine works in the unfrozen season on sites that cannot bear heavy equipment – the method's strength is weighted toward soft-soil sites and the snow-free season.
Does pienuratekniikka suit continuous-cover silviculture?
Compact machinery offers continuous-cover forestry combinations a heavy chain cannot – for example, felling as manual chainsaw work with forwarding by a small forwarder, without established strip roads. The options are covered on "Trail configurations for compact machinery".
Is there a state subsidy in Finland?
There is no separate subsidy for the first thinning itself. Young-stand improvement, however, can be eligible for the state's Metka subsidy, and compact forest machinery suits that work as well. Eligibility is based on the site, not the harvesting method. Terms and current amounts should be checked with the Finnish Forest Centre.
How much yield do conventional strip roads cost?
A road's nominal width overstates the loss: roadside crowns use the open space, and the true growing-area effect of a roughly 4-metre road is about 1.5–2 metres from its centre line. But the loss is permanent and repeats along every road. The precise yield effect over a full rotation period is exactly the question the ongoing research measures.
How much fuel does a compact forest machine use?
According to ErkkaTec's machine-tracking data, the Alstor harvester consumes on average 3 litres per hour and the forwarder 2 litres per hour. The corresponding figures for a full-size chain are roughly 13–17 l/h for the harvester and 9–13 l/h for the forwarder (puuhuolto.fi, energy-efficiency guide, in Finnish). Per cubic metre the difference is significant: at the tracked productivity, the compact chain consumes about 1 l/m³, while a full-size chain averages about 3.2 l/m³ in first thinning. At current fuel prices the difference is in the order of €4/m³ in the compact machine's favour. Fuel is still only one part of total harvesting cost; the full comparison is being examined in research.