For an owner of a coniferous forest managed as a traditional plantation, it is essential to know whether conversion to close to nature forest management is economically viable. LIFE 4Forest is now investigating the subject in a project focusing on the yield and economics of close-to-nature forest management.
>> Read more about Life4Forest here
What Can Be Sold?
Logging machines collect data on 10 test areas, providing detailed information on the dimensions of the trees when harvesting the forest according to close-to-nature principles. What can be sold, and which assortments are produced; timber, three meter wood, pulpwood, etc.?
The goal is to demonstrate the difference in the economy of harvesting activities between traditional plantation forest management and the new close-to-nature management approach and analyze the average revenues per cubic meter of harvested wood – ideally over a tree generation. This is demonstrated by collecting data from various stands of different ages and different stages of conversion to close-to-nature management.
Harvesting Trees "From the Top"
In traditional plantation management, the small and less desirable trees are continuously harvested to promote the growth of larger, preferably uniform trees, which are eventually clear-felled – all at once - followed by planting.
Harvesting Based on Target Diameter
In close-to-nature forest management, trees are continuously harvested when they reach their target diameter, meaning they are so large, that the value growth starts to decrease. This results in the harvesting of large trees (thought also of poor-quality trees) – called "from the top" harvesting – to promote a sustainable, diverse, and stable forest. The forest is never clear-cut but can be harvested continuously because the small trees left behind continue to grow.
This harvesting method has two clear consequences:
- The dimensions of the harvested wood over time are larger (and therefore better paid) than in traditional harvesting.
- Since there is no aim for a uniform final stand, the diameter distribution between the trees in the remaining stand is maintained or increased. In subsequent harvests, younger trees reach the target diameter and are ready for harvesting.
Lower expenses for planting
In ideal close-to-nature forest management, the trees will only be harvested from the upper canopy.
The opening created by felling provides light for new growth and natural regeneration of the forest. Therefore, there is no need for planting new trees, and there is no thinning of small trees, as in traditional plantation management. In many cases, trees may be planted to supplement with new species, that can enhance stability and diversity. For example, Douglas fir and Grand fir may be planted for timber production, or beech and other hardwood species to improve stability in a spruce plantation.
Steady Cash-Flow
The expectation is that with this harvesting method, a more stable economy is achieved because harvesting large trees every 3-5 years generates income continuously - in principle, indefinitely. Experiences from Germany already point in that direction.
Trees of Different Ages
With close-to-nature forest management, the age diversity becomes significant. The trees at the very top are called dominant trees. A significant portion of them is left standing as an upper story because they provide stability to the stand and ensure seed production for natural regeneration. Instead, the so-called intermediate and co-dominant trees are felled.
New Job for the Forest Machine Operator
In Rold Skov, over the past 10 years, machine operators have been given a new set of instructions for this type of harvesting: cut approximately 5% of the stem count. Fell among the large trees that have reached the target diameter. Cut down diseased trees but leave a series of large trees with a large crown. There should be approximately 50 large trees per hectare with large crowns left. They ensure stability in storms and produce seeds as a source of natural regeneration. Instead, the machine operator needs to know which trees are intermediate and co-dominant and selectively harvest them.
Here are three examples of top-cutting, where a series of large trees are left as a screen. Feldborg Nørreskov. Photo: Jens Peter Clausen, Forest Ranger at the Danish Nature Agency.
This means that the job for the machine operator becomes more complex. There are no longer rows of trees, small trees at the bottom do not need to be removed, and analysis is required to determine which trees should be felled.
Logging Machines Create the knowledge
The experiment currently covers 10 stands in Feldborg Nørreskov. In these stands, Nanna Karoline V. Frank, Forest and Landscape Engineering intern at the Danish Nature Agency Himmerland, has been out with a caliper to measure diameter and height before logging.
After logging, the logging machine retrieves precise data, such as tree species, assortment outcome (which products the tree is cut into), dimensions, time, and location for each tree. This allows us to analyze the portion of wood mass removed from the stand and what can be sold by comparing diameter and length with the pre-logging measurements.
By collecting and analyzing data from various stands at different stages of conversion to close-to-nature forestry, the goal is to describe the yields in both wood mass and money that forest owners can expect if they decide to convert. In other words, forest owners get an opportunity to assess whether conversion can be attractive to them, including from an economical perspective.
Cultural Change on Its Way
"When we want to implement close-to-nature forestry, we, as forest managers, need to change our perspective on the forest," says Bendt Egede Andersen, who leads the experiment and is part of the LIFE 4Forest steering committee. He anticipates a cultural change in the cultivation of coniferous forests.
"We should see ourselves more as stewards of a sustainable ecosystem from which we can harvest, rather than just as timber producers. For me, close-to-nature cultivation makes sense on all fronts: both biologically and economically. We create more variation, less vulnerability, and we safeguard against catastrophes that have previously devastated forests. If we can also demonstrate that the economy can compete with traditional plantation management, then there are strong arguments for conversion."
The LIFE 4Forest project concludes in 2028, where the results from this experiment are also complied.
Written by Janne Bavnhøj