The regeneration patterns of mixed spruce-birch stands

The mixed Norway spruce (Picea abies (L.) Karst.) and birch (Betula pendula Roth & Betula pubescens Ehrh.) stands are stages of secondary forest succession in Estonia. Mixed spruce-birch stands establish themselves after clearcutting and grow under different silvicultural treatments. The initial stages of stand development are affected by silvicultural treatments as well. These are two main factors explaining the regeneration success and stand structure in premature and mature stands. First: the number of advance regeneration spruces surviving after clearcutting and, second, the birch thinning in stand youth. The usual pattern after clearcuttings on fertile sites is the development of birch dominated stand with spruce in suppressed position. Birch is known as a pioneer in Estonian forest growth conditions. If the sufficient number of spruces make up advance regeneration and birch is thinned in stand youth the mixed stands of spruce and birch having both species in dominant stand develop.