Page 22 - Green knowledge 2023

No quick fix for clear-cutting methods
To test alternatives to clear-cutting, NIBIO and partners are conducting new trials with old harvesting methods.
In Norway spruce, even-aged management with clear-cutting and replanting has been dominant in Norwegian forestry for 80 years, leading to much greater growth than a century ago. However, the downside is sudden changes in the forest landscape, with new clear-cut areas and dense, single-layered forest - which can be perceived as both monotonous and unattractive for recreational purposes.
Are there alternatives to current methods that can create more variation in the forest landscape while delivering good economic results to the forest owner and ensuring high timber production?
Recent analyses of older trials with selective cutting have shown that productivity can be equal to even-aged management, provided that sufficiently high standing volume is retained after the selective cutting. However, successful selective cutting requires a multi-layered forest structure, which is
lacking in much of the Norwegian spruce forests established after the introduction even-aged management in the mid-20th century.
In collaboration with partners, NIBIO is therefore testing new methods aiming to gradually convert young spruce stands towards a forest with a struc- ture suitable for the selection system. The starting point is the concept of “Variable Density Thinning,” previously tested in the state of Oregon, USA.
The project is unique in Nordic context. Long-term trials and demonstration plots are being established, where the concept is tested under Norwegian conditions. The aim is to create space for the development of smaller trees and regeneration, thereby also creating a multi-layered forest suitable for using the single-tree selection system in the long run.
Photo: Aksel Granhus
Purpose: Collaboration: Funding:
Contact:
To find alternative harvesting methods to clear-cutting
Norwegian University of Life Sciences, Statskog, and forestry industry organizations The Norwegian Forestry Fund and The Development Fund for Forestry
Head of Department/Head of Research Aksel Granhus. Email: aksel.granhus@nibio.no, phone: (+47) 977 14 873. Division of Forest and Forest Resources
20