Question 1

What harvesting method does Hyggligt use?

Accepted Answer

We use continuous-cover, data-driven precision harvesting (hyggesfritt) based on centered selection cutting (centrerad plockhuggning). Hyggligt builds software that calculates which trees should be removed. Forest data is collected with drones and the conditions of each individual tree are analyzed. Decisions about which trees to harvest are made by our optimization model, built on the latest research. The model accounts for the landowner’s required return and desired risk level, each tree’s local competition for resources and growth, and current timber prices. This results in mature trees being selected for harvest while smaller trees are left to grow. Tree selection is adapted for the forest’s long-term profitability. The harvester operator can see directly on their in-cab screen which trees are recommended for harvest. With Hyggligt’s harvest planning, the forest regenerates naturally and becomes more layered. Extraction is typically 25–40% of basal area (grundyta), and harvests are generally planned at intervals of 8–20 years depending on site conditions.

Question 2

What forests and site types are suitable for Hyggligt’s harvest planning?

Accepted Answer

Centered selection cutting (centrerad plockhuggning) can be used in all production forests, but the structure of the starting stand determines whether it is the most profitable option right from the first operation. If the forest is suitable for forestry, it is also suitable for selection cutting (plockhuggning). Multi-layered stands can grow and be optimized in many conditions, but some stand types require a careful transition to selection cutting, which reduces profitability during the conversion period. Above all, the method is well-suited for forests where both profitability and biodiversity should be supported long term.

Question 3

How large is the extraction in a harvest?

Accepted Answer

Extraction depends on several factors—such as current timber prices, site productivity (bonitet), and windthrow risk—but is typically between 25% and 40% of basal area (grundyta).

Question 4

Are any additional silvicultural actions needed, such as planting or pre-commercial thinning?

Accepted Answer

In general, the answer is no. With centered selection cutting (centrerad plockhuggning), we rely on natural regeneration and let the forest take care of itself as much as possible. There is a fairly high degree of random variation in what regenerates after a harvest—both in how many seedlings appear and how evenly they are distributed. Our optimization algorithms take species into account and help create a suitable density to promote good natural regeneration of the same species being harvested. In most cases, natural regeneration will be sufficient. In some cases, gaps may need supplementary planting. In other cases, dense regeneration may benefit from thinning so individual trees can develop healthy crowns.

Question 5

Is the logging/operation cost higher than with clear-cut forestry?

Accepted Answer

Harvesting cost is often higher for selection cutting (plockhuggning) than for clear-cutting, but typically on par with a second thinning. Depending on tree size, a final felling harvester may sometimes be needed instead of a thinning machine, but in most cases you can expect costs similar to a second thinning. Cost per harvested cubic meter mainly depends on extraction intensity and average stem size. Measurements from 2021 indicate a cost per harvested cubic meter of about SEK 140 at 1.5 m³ average stem volume and about SEK 110 at 1.0 m³ average stem volume. When extraction is below 30%, costs usually rise a bit. In a fully multi-layered stand, the higher harvesting cost is often offset because extraction is focused on trees in higher-value sawlog dimensions, improving net revenue.

Question 6

Will future harvests be the same size?

Accepted Answer

The short answer is: it depends on the return the landowner expects from the forest, which species should be favored, and how dense the starting stand is. For example, if you start with a Norway spruce stand with a basal area of 30 m²/ha, a first extraction of 30% leaves 21 m²/ha. That extraction level isn’t necessarily sufficient to ensure optimal growth; it’s a compromise to avoid making the stand too wind-sensitive. By the third harvest, extraction may be lower than 30% to avoid making the stand too sparse. Over the long term, for ingrowth you may aim for a basal area around 10 m²/ha. Before a fourth thinning-out, you may want to wait longer—around 20 years—but it can still be sensible to target an extraction of about 30% to keep harvesting costs down. Hyggligt also recommends accounting for the forest ecosystem when setting extraction levels, meaning the harvest must not be too heavy, since that has a greater impact on biodiversity. The size of harvests and the interval between them can therefore vary based on forest conditions and the landowner’s goals. In practice, our planning algorithms are adjusted using the required return and the chosen extraction level.

Question 7

What will the forest look like in 30, 50, or 100 years using Hyggligt’s harvest planning?

Accepted Answer

The forest will move toward a fully multi-layered structure while the growing stock is kept at a relatively stable level. Hyggligt’s optimization algorithm is the result of extensive simulations, including discounted cash-flow calculations over hundreds of years and millions of different tree-selection scenarios. Part of that optimization is ensuring the algorithm maintains forest structure (layering) so management can generate optimal net revenue over a long period. What the forest will look like that far into the future does not directly affect the optimization of today’s harvest, because tree choices are evaluated based on current conditions—i.e., how the stand and tree groups look today.

Question 8

Does individual-tree management matter? Does it matter which trees are harvested or left?

Accepted Answer

The short answer is yes—especially for the landowner’s profitability. Exactly where trees stand is not that important for growth, at least as long as they are not so close that their crowns suppress each other. But which trees you remove matters a great deal for profitability. Optimal tree selection is largely about matching a tree’s target diameter to its ability to produce value. When a tree reduces the group’s total value growth, it’s time to harvest it.

Question 9

How can you optimize a harvest if you don’t know exactly how the remaining trees will grow?

Accepted Answer

Using optimization algorithms means that the selection rules for which trees are optimal to remove have already been computed based on more or less extensive calculations and simulations of how trees behave in different situations. So, to optimize tree selection you don’t need to calculate the exact growth in every individual case; the optimization rule (the algorithm) is based on the choice that has proven most likely to be optimal under a given set of conditions. These algorithms depend on species, discount rate, and the basal area (grundyta) around the tree. Hyggligt’s algorithms are also adapted to the current timber market price picture. These adjustments are based on the current state of knowledge and research literature. That said, some important characteristics are still left to the harvester operator to account for—such as timber quality and tree vitality. Hyggligt’s ambition is to incorporate those aspects into the algorithms over time. Given existing knowledge gaps, there is no major risk inherent in this kind of tree-selection optimization. In the worst case, the target diameter for an individual tree might end up somewhat off from the theoretically true optimum. It’s also crucial to set reasonable return requirements for the forest that do not exceed what the forest can produce—otherwise, the outcome can eventually be a clear-cut. In short, extraction is optimized based on fairly strong probabilistic knowledge of how trees are most likely to respond.

Question 10

Do you need to file a harvest notification with Hyggligt’s method?

Accepted Answer

Even though this is a continuous-cover method, in some cases you may need to file a harvest notification. That depends on whether the remaining stand becomes sparse enough to be considered a regeneration harvest under the Swedish Forestry Act. This is regulated by the Forestry Act (1979:429).

Question 11

What machines do you use for harvesting?

Accepted Answer

Machine type is driven by average stem size and the distance between forwarding trails (stickvägar). We usually recommend 4-meter-wide trails with about 20 meters between them. In that case, a second-thinning harvester is often ideal as long as stump diameters don’t exceed ~50 cm by much. In very heavy timber, a final felling harvester may be a better fit. For forwarders, we often recommend smaller models to reduce the risk of soil compaction and rutting damage in the remaining stand. More important than the machine choice, however, are skilled operators who adapt to ground bearing capacity and protect the remaining forest. Using the delimbed branches as a driving mat is important to minimize soil compaction.

Question 12

Which contractors do you work with?

Accepted Answer

Harvesting is carried out by local contractors near your forest. Our goal is to always work with local companies with experience in selection cutting (plockhuggning). Timber is then sold through Treebula, unless the forest owner or contractor has other preferences.

Question 13

I have my own contractor and/or want to sell the timber myself. Can Hyggligt still help with analysis and tree selection?

Accepted Answer

Yes—absolutely.

Question 14

Does selection cutting reduce volume growth compared to clear-cut forestry?

Accepted Answer

The short answer is no—or at most, marginally. Before answering, it’s important to note that strong profitability primarily depends on directing growth into the most valuable stems: large trees with good quality. If you maximize growth at all costs, you tend to end up with smaller stems, higher harvesting costs, and more trees that die from competition. When people compare volume growth, they usually mean mean annual increment over a rotation (omloppstid). The research most often cited concerns “blädning” (uneven-aged management) in Norway spruce stands, which generally have a higher share of large trees. Most results show no difference between that approach and clear-cut forestry, but some studies show lower growth under uneven-aged management. Overall, if there is a measurable difference in volume growth between selection cutting (plockhuggning) and clear-cut forestry, it is likely not very large. A key factor that drives volume growth—both in multi-layered and even-aged management—is how harvests are executed: removing the right trees and keeping extraction at appropriate levels is, in practice, more important than the choice of method itself or how much volume remains after harvest.

Question 15

Can light-demanding species like Scots pine be profitable in a multi-layered stand?

Accepted Answer

There is some skepticism about managing toward a multi-layered forest dominated by pioneer species such as Scots pine. One main reason is that pioneer species are more sensitive to shading from larger trees compared to secondary species such as Norway spruce. A counterargument is that by keeping the stand more open, young pines can receive enough light to establish and grow. Studies in Finland suggest that an appropriate density for a multi-layered pine stand is often around 5 m²/ha. That implies selection cutting would be fairly heavy—close to shelterwood and gap cutting. This can mean some loss in volume compared to an even-aged pine regime, but it can also create the potential for significantly higher value production on the volume that is produced. Some studies indicate that systematically selection-cut pine stands produce about 25% first-class sawtimber, compared to about 3–4% in forests managed with clear-cut forestry. Also remember that around 25% of the produced volume in clear-cut regimes is removed as low-profit thinning and pre-commercial thinning trees—which is substantially more than in a multi-layered stand. That said, much more research is needed on selection cutting in pine stands before a definitive answer is possible. In general, it’s wise to be cautious about planning for fully multi-layered, single-species stands dominated by pioneer species. However, it can be a sound strategy to maintain a stand density that promotes strong elements of pioneer species in the selection-cut forest.

Question 16

Will the forest get damaged if large harvesters operate every ten years?

Accepted Answer

Selection cutting (plockhuggning) does mean that each harvested cubic meter is transported a longer distance on average compared to final felling. Potential damage includes felling damage to remaining trees, soil compaction (especially during forwarding), and other root and stem damage caused by machines. However, there is no general relationship between selection cutting and the amount of damage. By contrast, there are many studies showing rutting damage associated with clear-cut operations. In practice, the risk of rutting damage depends far more on the operator than on the management system. A poor operator can cause substantial damage in selection cutting just as in a standard thinning. Hiring skilled operators and ensuring they work under reasonable conditions is essential. Piece-rate compensation is often a poor fit for selection cutting. A skilled operator fells trees where they cause the least damage and ensures enough slash is laid down when bearing capacity is low—or adapts the load to conditions. Also, a poorly managed forest with tall, dense trees will experience more stem damage than a well-managed one. But a professional operator with good conditions should not cause stem damage to more than a few percent of the remaining trees, and the machine trails should not show meaningful compaction. There’s a common belief that selection cutting means more interventions in the forest. What’s often overlooked is that a standard clear-cut regime also involves several machine interventions over a rotation: final felling, site preparation, two thinnings, and then the cycle repeats with a new final felling. In southern Sweden, with a rotation of 70 years, that averages out to one intervention every 14 years.

Question 17

Does storm risk increase when the stand is opened up?

Accepted Answer

Storm risk always increases when a stand is opened up, regardless of management system. However, a multi-layered stand harvested through selection cutting is significantly more windfirm than an even-aged stand managed under clear-cut principles. During the transition from even-aged to multi-layered structure, the stand can be more storm-sensitive. That said, there are several ways to be proactive and reduce risk. Depending on stand history and assessed risk, extraction can be adjusted. The layout of forwarding trails (stickvägar) also matters—for example, planning trails opposite the prevailing wind direction. Hyggligt accounts for these factors in harvest planning.

Question 18

Can an even-aged stand be converted to a multi-layered, continuous-cover stand?

Accepted Answer

Yes—an even-aged stand can be converted to a more layered structure. Hyggligt’s tree-selection algorithms enable that conversion by sizing harvests to gradually open up the forest. Spreading harvests over a longer period is important to limit storm sensitivity. The younger and better-thinned the forest is, the faster the conversion period. We’ve set extraction caps at 30% for spruce and 40% for pine. The timeframe and the economics during conversion also depend on how much structural variation exists initially. Most stands have some diameter spread even when planted at the same time, and it becomes important to maintain and increase that variation. If the forest is old and dense, conversion is more challenging, and it may no longer be justified on profitability alone. Hyggligt can help determine whether a stand has passed the threshold where conversion is economically reasonable.

Question 19

Is the Swedish Forestry Act a barrier to continuous-cover forestry?

Accepted Answer

For most Swedish forests, the current Forestry Act is not a barrier. That said, there are two parts of the Act that can sometimes create friction for continuous-cover forestry. The first concerns the requirement to report a regeneration harvest if the remaining growing stock falls below a certain level (Section 5). The second concerns minimum stand age before such a “regeneration harvest” may be carried out (Section 10). Both requirements are a somewhat awkward fit for multi-layered forestry because the rules were developed in an era when they were intended to regulate clear-cut forestry. The goal is to keep the forest dense enough to maintain production until final felling. In selection cutting, however, the goal is to keep the forest open enough to regenerate continuously. As a result, a landowner using selection cutting may need to submit a regeneration harvest notification each time a stand is harvested, depending on how sparse the stand becomes after the operation. Still, it’s rare for a measure to be blocked by the Act for these reasons. There can, however, be cases where you need to wait until the stand’s mean age reaches the minimum allowed level, which in the worst case can make it harder to achieve desired extraction levels and remaining volume.

Frequently asked questions

Hyggligt

Continuous-cover forestry and selection cutting