An alternative to clear-cutting in the boreal forest of Alaska: a 27-year study of regeneration after shelterwood harvesting

We present 27-year results from a comparison of clear-cutting and shelterwo od harvesting in the boreal forest of Alaska. Three patch clear-cut and thr ee shelterwood units were harvested in 1972; about 100 dispersed white spru ce (Picea glauca (Moench) Voss) leave trees per hectare were retained in th e shelterwoods. Units were mechanically scarified and an exceptionally larg e seed-crop was dispersed that year. Shelterwood trees were removed after 1 5 years. After 27 years, overstory treatment had no effect on the density o r growth of the species we studied, while scarification had highly signific ant effects. In 1999, scarified areas were densely populated with white spr uce seedlings and saplings (118 000 - 129 000 stems/ha, with spruce in 100% of plots). Unscarified areas had far fewer spruce stems but were neverthel ess well stocked (11 000 - 15 000 stems/ha, with 87% frequency). Initially, spruce grew best on scarified surfaces, but by 27 years, growth of the tal lest spruce saplings was significantly greater on unscarified than scarifie d surfaces. By 27 years, cover of the grass Calamagrostis canadensis (Michx .) Nutt. had returned to preharvest levels in all treatment types. Because criteria for evaluating forest management practices have changed since this study was begun, partial overstory retention systems for the management of Alaska's boreal forest deserve further study.