%0 Research article
%T Microsite occupancy and the spatial structure of understorey regeneration in three late-successional Norway spruce forests in northern Europe
%A Grenfell, Russell
%A Aakala, Tuomas
%A Kuuluvainen, Timo
%D 2011
%J Silva Fennica
%V 45
%N 5
%R doi:10.14214/sf.89
%U https://silvafennica.fi/article/89
%X We compared microsite occupancy and three spatial structure of  regeneration in three primeval late-successional Norway spruce dominated  forests. One area lay in the middle boreal zone in Russia  (Dvina-Pinega) where larger-scale disturbance from bark beetles and  drought had occurred; the other areas lay in the northern boreal zone,  one in Finland (Pallas-Ylläs) had encountered only small-scale  disturbance, and one in Russia (Kazkim) had been influenced by fire. We  mapped all spruce (Picea abies) and birch (Betula pendula and Betula  pubescens) trees with diameter at breast height (DBH) ≥ 10 cm on 40 m    400 m plots, and those with DBH < 10 cm on 2 m or 4 m   400 m  subplots. On the subplots we also recorded microsite occupancy and  estimated microsite availability. At all study areas small seedlings  (h < 0.3 m) of both spruce and birch were found largely on  disturbance-related microsites. Birch saplings (h ≥ 1.3 m, DBH <  10 cm) disproportionately occupied deadwood-related microsites at  Dvina-Pinega. In contrast, spruce saplings at all study areas, and birch  saplings at Kazkim and Pallas-Ylläs, showed less, or no, preference.  Our results thus confirm the importance of disturbance-related  microsites for regeneration establishment, but not necessarily for  long-term survival. No spatial segregation between the overstorey (DBH ≥  10 cm) and saplings (h ≥ 1.3 m, DBH < 10 cm) or seedlings (h <  1.3 m) was found at Pallas-Ylläs or Kazkim, and only three instances of  very weak segregation were found at Dvina-Pinega. This suggests that the  regeneration gap concept may not be useful for describing the  regeneration dynamics of primeval boreal forests.