Thinning a little but often can increase timber profits. When the early thinning is done from the air, the need for strip roads disappears, which reduces ground contact and thus consequential damage.
Photo AirForestry
Thinning is not just about how much wood is removed, but about how the remaining forest develops. When competition decreases, trees can grow faster in diameter and a larger part of the volume develops into timber. At the same time, long-term trials show that too much thinning can reduce total volume production.
-
The WeighPro Wireless Weighing Link represents a precise and dependable weighing system designed specifically for round timber, eliminating the need for re-calibration. This system offers operators minimal maintenance requirements, boasting an impressive battery life of up to two years between recharges.
-
That’s a remarkable amount of work hours for a single machine, the Norcar 600 owned by Erkki Rinne is taken well care of, it even has the original Diesel engine.
-
It is not possible to eliminate chain shot, but there are simple steps that can be taken to reduce the risk.
-
Arwel takes great pride in the fact that the mill has no waste whatsoever, “the peelings are used for children’s playgrounds, gardens and for farm animals in barns in the winter and the sawdust has multiple uses in gardens and farms as well.
-
Timber hauliers need to encourage young blood in, and also look after the hauliers we have, we need make the sector a safe and positive place to work.
FIND US ON
For pine, the correlation is clear: weak thinning causes little production loss, while moderate and strong interventions can significantly reduce growth. Spruce seems to compensate better after moderate thinning, but even then the risk of loss increases as harvest increases.
This makes thinning more frequent but less interesting. Instead of a few major interventions, the stand can be affected gradually, and thinning can better adapt to base area, trunk number, and stand structure. This provides more room to steer the stock toward the desired diameter development without making the same amount of withdrawals each time.
In the Eureka simulation, we compared two hypothetical thinning strategies. Conventional thinning means thinning by 30–45 per cent during the rotation period, using strip roads. Drone thinning meant repeated thinning, averaging 2.5 thinnings per stand, with a removal rate of 5–20 per cent, without strip roads. We assumed all thinning in the latter alternative could be carried out with drones. In practice, there is a weight limit of about 200 kg per tree, which was not exceeded in the simulations.
Over the orbital period, the drone strategy resulted in a 5.6 per cent increase in net volume production and a 9.5 per cent increase in net timber volume production. When you exclude the difference in rotation time, the increase in total volume was small, but net timber production was still 4.2 per cent higher per year. It is only when you have more timber and less production loss that the potential becomes clear.
Strip roads cost production space
Conventional thinning requires strip roads for harvesters and forwarders. They take up productive space and mean that machines’ need for accessibility controls part of the outlet. Nordic studies show that removing strip roads can result in about 8–10 per cent lower volume growth over a ten-year period.
If trees can instead be removed from the air, the need for strip roads can be greatly reduced or eliminated. Then more trees can remain and the choice of trees can be controlled more by which trees should be developed further. The focus can be shifted from where the machine has to go to how best to develop the stock.
Less ground contact can result in less consequential damage
Direct machine damage after a well-executed thinning is often limited, usually to a few per cent of the remaining trees. But the injury rate doesn’t tell the whole story. An injury near the root neck or on a coarser root can affect growth and increase rot risk.
Repeated driving can also cause rutting, compaction, and a poorer root environment, especially in moist, sensitive soils. Heavy thinning can also increase the stand’s sensitivity to storms and snow. The biggest losses therefore may not occur when the machine passes, but can appear much later.
Thinning from the air would reduce ground contact and the need for machine movement inside the stand, which can limit soil, root and trunk damage. Weaker interventions can also reduce changes in stand structure that increase the risk of storm damage, the greatest damage potential after thinning. Rot damage, on the other hand, develops more slowly, can only be detected several years later, and affects future volume.
Can open forest that is currently difficult to thin
The GIS analysis shows that the greatest geographical potential is in steep terrain. More than 570,000 hectares of non-formally protected forest land with about 94 million m were identified.3so-called standing timber. Forested bog islets represent a less complementary possibility. The figures show geographical potential; the practically available area depends on factors such as thinning needs, natural values, technology, logistics, and finances.
The potential lies in how several effects interact
The results cannot be added together into a single volume. They describe different parts of the same opportunity: maintaining more productive area, steering growth toward timber, reducing certain damage risks, and, in some cases, reaching stands that were previously difficult to thin. This combination of effects is what makes the technology interesting from a forest management perspective.
Overall, the results point to a more flexible thinning system, where the forest’s development controls tree selection more and the machines’ accessibility requirements less. The potential can be summarised as follows:
- Fewer or no branch roads and thus less production loss.
- More and weaker thinnings that better preserve the stand’s production capacity.
- Higher timber production and thicker trees in final felling.
- Less ground contact and the potential to limit certain long-term damage risks.
- Greater freedom in tree selection and the opportunity to access certain hard-to-reach forests.
The results are promising but still indicative. The next crucial step is long-term comparative field trials that monitor forest development, damage, timber quality, technology performance, and economics together. These experiments can show how much of the potential can be realised when thinning from the air meets real stands and conditions.
Source; Skogsforsk
Contact forestmachinemagazine@mail.com to get your products and services in front of the world’s largest professional forestry online news network.
#homeoflogging #writtenbyloggersforloggers #loggingallovertheworld
Written by loggers for loggers and dedicated to bringing you the latest forestry news