EGU23-2639, updated on 09 Jan 2024
EGU General Assembly 2023
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Fast recovery of suppressed Norway spruce trees after selection harvesting on a drained peatland forest site

Aleksi Lehtonen1, Kersti Leppä1, Katja Rinne-Garmston1, Elina Sahlstedt1, Pauliina Schiestl-Aalto2, Juha Heikkinen1, Giles Young1, Mika Korkiakoski3, Mikko Peltoniemi1, Sakari Sarkkola1, Annalea Lohila3, and Raisa Mäkipää1
Aleksi Lehtonen et al.
  • 1LUKE - Natural Resources Institute Finland, Luonnonvarat ja biotuotanto, Helsinki, Finland (
  • 2University of Helsinki, Hyytiäläntie 124, FI-00014 Helsingin Yliopisto, Finland
  • 3Finnish Meteorological Institute, Erik Palménin aukio 1, FI-00560 Helsinki, Finland

Continuous cover forestry (CCF) has been promoted as an environmentally sustainable option for drained peatlands. The CCF management has been challenged due to potentially lower tree growth compared to traditional even-aged management, especially with suppressed trees that are released during a selection harvesting under CCF management.

Our objective was to quantify the time lag of stem diameter growth response of suppressed Norway spruce trees (Picea abies Karst.) after a selection harvesting compared to that of dominant trees. We also tested if the carbon assimilation of the trees increased immediately after selection harvesting. We used radial increment cores from suppressed Norway spruce trees to estimate the impact of selection harvesting on the diameter growth and intrinsic water use efficiency (iWUE). We measured carbon isotope composition (δ13C) of wood, to quantify how the reduced competition between trees altered iWUE and its components, the photosynthetic rate (A) and stomatal conductance (g).

The study was conducted in the Lettosuo experimental site on fertile forestry drained peatland area in southern Finland. Approximately 70 % of the initial stand area (18.5 ha) was harvested according to CCF principles by applying selection harvesting, and the rest of the area was divided to intact control area and to clear-cut area. In the study site, by selection harvest, trees were removed from multiple age classes, but especially mature trees individually or in a small groups were taken away to maintain uneven-aged structure of the forest. All the target trees grew in the similar competitive position before selection harvesting.

Our results show that there was a delay with the diameter growth of the suppressed trees to selection harvesting, whereas the most significant growth-enhancing effect occurred three-four years after selection harvesting. In contrast to the delay in the increment, the photosynthetic rate relative to stomatal conductance increased immediately after selection harvesting, as shown by the instant 2.5‰ increase in δ13C to a post-harvest level.

Our results show that carbon uptake increased immediately for suppressed Norway spruce trees after selection harvesting, but the harvest did not induce a clear increase in stem diameter growth during the first years after the harvest.

How to cite: Lehtonen, A., Leppä, K., Rinne-Garmston, K., Sahlstedt, E., Schiestl-Aalto, P., Heikkinen, J., Young, G., Korkiakoski, M., Peltoniemi, M., Sarkkola, S., Lohila, A., and Mäkipää, R.: Fast recovery of suppressed Norway spruce trees after selection harvesting on a drained peatland forest site, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2639,, 2023.