%0 Review article
%T Variability and dynamics of old-growth forests in the circumboreal zone: implications for conservation, restoration and management
%A Shorohova, Ekaterina
%A Kneeshaw, Daniel
%A Kuuluvainen, Timo
%A Gauthier, Sylvie
%D 2011
%J Silva Fennica
%V 45
%N 5
%R doi:10.14214/sf.72
%U https://silvafennica.fi/article/72
%X Due to the unprecedented loss of old-growth forests to harvesting  throughout circumboreal regions an understanding of  similarities and  differences in old-growth dynamics is needed to design effective  restoration, management and conservation efforts. This paper reviews  concepts, prevalence and variability of old-growth forests across  landscapes, and evaluates different stand scale dynamics at the  old-growth stage across the circumboreal zone. Old-growth historically  dominated many boreal forest landscapes in both Eurasia and North  America. Throughout much of North America, and to some extent in western  Siberia, the natural prevalence and development of old-growth forests  are regulated by the occurrence of stand-replacing fires. In eastern  North America and Siberia, insect outbreaks may, however, be more  important. Insect outbreaks as well as recurrent non-stand replacing  surface fires and windthrows, when occurring at the old-growth stage,  often form stands characterized by several tree age-class cohorts. This  multi age-class forest development type is common in Europe and eastern  Siberia but its prevalence and importance in boreal North-America is not  well documented. Similarities in successional dynamics across the  circumboreal region are found in the development of mono-dominant  even-aged stands, the replacement of shade intolerant tree species by  shade tolerant species, as well as in all-aged stands driven by  small-scale gap dynamics. The message to land managers is that the focus  should not only be on setting aside remaining old-growth forests or in  restoring static old-growth attributes, but also in emulating natural  disturbances and successional dynamics at landscape and regional scales  to maintain natural variability in old-growth attributes through time.