Forest management in the research areas

	Photo: Metla/Matti Koivula

Forest management models based on natural dynamics will be applied on large research areas (700-1000 ha). Specific management regimes are applied to steer the development of forests towards structural complexity at both stand and landscape levels. This type of management is hypothesized to support biodiversity and other non-timber values better than the current management paradigm does. Simultaneously, the research areas will provide exceptional opportunities for research in and on structurally complex forests.

Treatment blocks

Each research area will be divided into blocks representing different management regimes. The blocks are continuous forest areas at least 100 ha in area. Each block represents a unique combination of disturbance zones (three levels) and management intensities (two levels). Consequently, one research area will typically have six blocks.

Disturbance zones

A disturbance zone represents a specific range of treatment patterns, based on a hypothetical counterpart (disturbance type) in natural forests. Forest structure within a given block is expected to attain the key characteristics of the comparable natural disturbance type within one rotation cycle (70-100 years).

Levels of management intensity

Each block also represents one of two levels of management intensity, which refers to the proportion of wood yield removed in harvesting in the long term. The levels are 90% and 50%. Reversed, the intensity can also be expressed in terms of the degree of tree retention (10% or 50%).

• Combinations of disturbance zones and management intensity levels in a research area
• Block division in the Isojärvi research area

Regeneration cuttings

Selection cutting (PoH) is based on the continuous maintenance of structural heterogeneity within a stand in terms of species, tree age, and tree size. A harvesting entry consists of the removal of individual large trees or small groups of trees. This treatment is mainly applied in stands that already are structurally heterogeneous, containing lots of advance regeneration. Logging interval is usually 15-20 years. A specific proportion of the stand is permanently retained in individual trees, groups, patches, strips, or stand sections.

In gap cutting (PiH), gaps with a diameter of 10-30 m are established for regeneration. The gaps have "fuzzy" edges: individual live trees are retained within the gaps, and individual large trees are selectively removed outside the gaps. Between the gaps, dense patches are thinned to maintain tree vigor and stability. A specific proportion of the stand is permanently retained in individual trees, groups, patches, strips, or stand sections. About 20% of the stand area (excluding the retention patches) is logged at each harvesting entry, which recurs every 20 years.

In partial cutting (OsH), gaps with a diameter of 40-60 m are established for regeneration. They can have variable shapes. Borders between the gaps and the remaining stand matrix forest are irregular and gradual. A specific proportion of the stand is permanently retained in individual trees, groups, patches, strips, or stand sections. During each entry, about one third of the area is logged, and harvesting recurs every 25-35 years. Thinnings are carried out to maintain tree vigor and stability

In clearcutting (AvH), the stand is harvested at once. A cutting and regeneration method that fits the site and stand conditions is selected among natural (seed-tree or shelterwood cutting) or artificial regeneration (clearcutting with direct seeding or planting). The harvested area varies between 0.5 and 5 ha. A specific proportion of the stand is permanently retained in individual trees, groups, patches, strips, or stand sections.

The alternative methods of regeneration cutting will be applied on the designated disturbance zones like this (proportion of area):

• Minor disturbance zone: gap felling 3/4, selection felling 1/4 of
• Partial disturbance zone: partial cutting 3/4, gap felling 1/4
• Severe disturbance zone: clear-cutting 3/4, partial cutting 1/4

Regeneration methods

Natural regeneration will be applied whenever feasible. If the prerequisites for natural regeneration are poor, direct seeding or planting are used instead. Existing advance regeneration is always spared and utilized. Site preparation (scarification, mounding, prescribed burning) is applied except in selection and gap cuttings.

Thinnings

In precommercial and commercial thinnings, the "skips and gaps" pattern is applied in order to promote development towards structural heterogeneity at all stages. Thinning intensity is to vary within a stand, e.g. by retaining small, very dense patches on the one hand and by creating open patches on the other.