Regeneration

Abstract

In the context of continuous cover forestry (CCF), natural regeneration is the preferred form of regeneration, but it is a long-lasting and complex process. Shelter density has a large effect on the regeneration process and results. The selection system, particularly suited for shade-tolerant species like Norway spruce, relies on continuous regeneration and ingrowth into larger size classes. Regeneration and ingrowth rates vary significantly among stands, influenced by site and historical factors, with no clear relationship to current stand conditions. In the group system, edge trees influence regeneration by providing seeds, checking weed growth, and exerting competition. Regeneration in gaps is generally satisfactory for both Norway spruce and Scots pine. However, seedlings usually grow slower, especially close to the gap edges. The shelterwood system promotes regeneration through a successive, uniform opening of the canopy. Shelter trees provide seeds, and reduce seedling damage and competition from ground vegetation. On the other hand, the remaining overstorey shelter trees reduce seedling growth. Conversion to the selection system initiates regeneration in young stands, aiming for slow and steady regeneration. Given the rapid growth and crown closure in young stands, frequent manipulation of shelter density is essential during conversion, for example by opening small gaps.