Regeneration dynamics in an uneven-aged virgin Norway spruce forest in northern Sweden

Abstract

The study was conducted at Kirjesålandet, a multistorey primeval Norway spruce [Picea abies (L.) Karst.] forest in northern Sweden. The objectives were: (1) to establish whether the presence of dead trees was associated with higher seedling density or growth; (2) to establish whether the influence of overstorey standing volume on height increment of seedlings differed between small and large seedlings; (3) to determine the time needed for seedlings to reach 1.3 m height; and (4) to estimate levels of recruitment, mortality and ingrowth into the tree layer, with equations using the relation between the height distribution and height increment of the seedling population. Seedlings (0.1–1.3 m height) and trees (diameter at breast height ≥5.0 cm) were measured on 46 circular plots. Presence of dead trees did not affect seedling density or growth. Height increment of small seedlings (0.1–0.5 m height) was unaffected by overstorey standing volume (range 13—333 m3 ha−1), whereas height increment of large seedlings (0.5–1.3 m height) decreased with increasing overstorey standing volume. Time to grow through the size interval 0.1–1.3 m was estimated as 58 years using height increment, and 50 years using analysis of annual rings. Seedling recruitment, annual mortality and ingrowth into the tree layer were estimated as 46 seedlings ha−1 year−1, 1.8% year−1 and 13 stems ha−1 year−1, respectively.