tynning

Tynning is a silvicultural practice in forestry that involves the deliberate removal of some trees from a stand to improve the growth, health, and value of the remaining trees. It is a key tool for managing stand density and structure, with the goal of enhancing overall forest productivity and resilience.

There are different forms of tynning: thinning from below, which removes suppressed and intermediate trees; thinning from above, which removes some of the larger trees to favor others; crown thinning, which selectively removes trees to promote crown expansion; and uniform thinning, which aims for a more evenly spaced stand. Thinnings are categorized as pre-commercial (no immediate revenue) and commercial (removal of merchantable trees). The choice of method depends on species, site conditions, and management objectives.

Objectives of tynning include increasing diameter growth in the remaining trees, improving wood quality, reducing competition for light, water, and nutrients, and promoting healthier regeneration. It can also influence stand structure and biodiversity. However, thinning involves costs, and improper execution can damage residual trees, compact soil, or disrupt ecosystem processes.

Planning and execution rely on assessing stand density through measures such as basal area and spacing targets, with timing tailored to species and site quality. Tynning is typically conducted after stand establishment and may occur in multiple successive thinnings over a rotation, reflecting long-term management goals.

Etymology: the term derives from Swedish tynning, meaning thinning. In forestry, it is used broadly across Nordic regions to describe this practice of selective removal to guide stand development.