Skjærtynning

Skjærtynning is a term used in Norwegian silviculture for a thinning method within a forest stand, where selected trees are removed to improve the growth conditions for the remaining trees. The name combines skjær (to cut or trim) with tynning (thinning). It is commonly applied in early to mid-rotation stands to reduce competition for light, nutrients and moisture.

Process and approach

Skjærtynning targets trees selected for removal based on form, health, growth pattern, and competitive position. Removed individuals are typically those that are suppressed, diseased, crooked, or otherwise likely to hinder the growth and quality development of crop trees. The goal is to create a more open canopy and better spacing for the remaining trees, thereby improving diameter growth and stem quality.

Timing and implementation

The operation is carried out when stands are sufficiently developed to identify crop trees but still responsive to reduced competition. It may be performed in one operation or as multiple passes, depending on site conditions, species, and management objectives. The practice is often used for conifer stands, such as Norway spruce and Scots pine, but can be adapted to mixed stands.

Effects and considerations

Skjærtynning can increase growth rates and improve wood quality of the residual stand, while also potentially enhancing resilience and biodiversity if conducted with ecological sensitivity. It requires careful assessment of stand structure, market considerations, and risk management, as over- or under-thinning can reduce yield or compromise stability.

See also

Thinning, selective thinning, silviculture, forest management.