SILVICULTURAL MODELS TO MAINTAIN AND RESTORE NATURAL STAND STRUCTURESIN SWEDISH BOREAL FORESTS

Almost all productive Swedish forests have been managed for timber pro duction for a long period of time. More sensitive so-called red-listed species are today restricted to small remnant habitats in a managed l andscape matrix. It has been hypothesized that natural biodiversity ca n be maintained if forest management mimics natural processes, blends natural structures and includes natural composition into the productio n forest. The most important restoration measures in Swedish boreal fo rests for promoting biodiversity are to increase the number and qualit y of undisturbed forests, the amounts of coarse woody debris, the numb er of deciduous trees, and to introduce fire as an ecological process. On the basis of current knowledge of natural forest dynamics, we here present management options for three major site types in boreal Swede n which mimic natural dynamics better than traditional forestry. In th e natural stages, the sites carried (1) Scots pine forest, (2) deciduo us or Norway spruce dominated forest, and (3) Norway spruce forest reg enerated by so-called gap dynamics, respectively. The flora and fauna that characterize the first two, fire-influenced sites are considered relatively well-adapted to the kind of large-scale disturbances charac terizing forestry. On these sites, therefore, the modifications propos ed are within today's approach to applying the clear felling system. S ites that seldom experience fire may host species extremely sensitive to large-scale disturbances. If such sites are to be used for timber p roduction, modified forestry practices using selection or shelterwood systems with relatively dense shelterwoods are suggested. (C) 1997 Els evier Science B.V.