Restoration of semi-natural forest after clearcutting of conifer plantations in Japan

We reviewed recent studies on the restoration of semi-natural forests after clearcutting of conifer plantations with specific reference to the importance of setting restoration goals, general and specific factors influencing restoration, and the prediction and judgment of successful restoration. For the restoration of semi-natural forests following the clearcutting of conifer plantations, recovery levels and appropriate restoration methods cannot be considered separately from the aims of restoration to provide ecosystem services. Restoration needs to be based on the setting of goals that correspond to the type and degree of ecosystem services targeted. When we aim to restore vegetation dominated by late-seral canopy trees within as short a period after the clearcutting of conifer plantations as possible, advanced regeneration in the pre-logged plantation is the most important and reliable source of post-logging regeneration, just as it is in the recovery of disturbed non-plantation forests. Advanced regeneration is not always present in plantations. Seedling establishment by seed rain from adjacent natural forest patches after a disturbance can contribute to late-seral or canopy species; however, the range of the edge effect is generally short, and the degree of the edge effect depends on the natural forest type and is more pronounced in deciduous forests, such as those in cool-temperate climates, or in forests with a complex forest structure. Thus, advanced regeneration is a better predictor of short-term forest recovery than measures based on seed rain from adjacent seed sources. However, restoration achieved only through advanced regeneration can simplify the species composition, and the recolonization processes of gradual species accession from seeds should be considered in the long-term context of restoration.