The effects of timber harvest, forest fire, and herbivores on regeneration of deciduous trees in boreal pine-dominated forests

Forest management fire and herbivores are the major factors affecting regeneration of deciduous trees in boreal forests. In a large-scale experiment we manipulated the use of prescribed burning the level of green-tree retention and the presence of moose (Alces alces L.) and hare (Lepus timidus L. and Lepus europaeus Pallas) to study their effects on early regeneration of three native pioneer tree species i.e. rowan (Sorbus aucuparia L.) aspen (Populus tremula L.) and silver birch (Betula pendula Roth). Green-tree retention enhanced survival of all tested tree species. Prescribed burning enhanced the survival rate of birch and rowan but aspen survival was only enhanced by burning on clearcuts and areas with 50 m(3)/ha of retention trees. Excluding moose enhanced rowan growth and birch survival. Aspen growth and survival was enhanced when both moose and hare were excluded. Seedlings were most frequently browsed on clearcuts and most seedling mortality was caused by voles or hare. At low densities the effect of moose on pioneer trees may be smaller than that of other herbivores or the fire-management regime. Considering the large number of species depending on pioneer trees the results support the use of tree retention and fire as useful management alternatives not only to promote biodiversity but also to enhance regeneration of deciduous trees and reduce herbivore damage.