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Doctoral thesis, 2001

Regeneration dynamics in uneven-aged Norway spruce forests with special emphasis on single-tree selection

Nilson, Kristina

Abstract

The thesis summarises results from four separate studies. One study reviews early Swedish regeneration studies (1830-1949) in multi-storied Norway spruce {Picea abies (L.) Karst) forests, subjected to single-tree selection and other forms o f partial harvests. The review identified shortcomings in the knowledge of regeneration dynamics in multi-storied forests. The other three studies, performed in central and northern Sweden, concern the effects of overstorey density, (expressed as standing volume, basal area and canopy openness), and the effects o f ground cover (bilberry [Vaccinium myrtillus L.] or herbs [e.g. Aconitum septentrionale Koelle]), on regeneration density and height increment. The studies included possible differences between multi-storied and shelterwood stand structure. Furthermore, recruitment, mortality and ingrowth rates were quantified.

Seven years after treatment sapling mean height increment decreased with standing volume in shelterwoods. Results in multi-storied stands were inconsistent. Ten years after harvests, sapling (0.5 m < h < 2.0 m) and small tree (h > 2.0 m, diameter at breast height < 5 cm) mean height increment increased significantly with canopy openness. Sapling growth showed high correlation with canopy openness, whereas small tree growth showed high correlation with basal area. A multi-storied structure was significantly negative for sapling and small tree height increment. Overstorey standing volume (range 13-333 m3 h a 1), did not affect seedling (h < 0.5 m) density and height increment, in a virgin forest in northern Sweden, whereas density and height increment of saplings (0.5 m < h < 1.3 m) decreased significantly with overstorey standing volume. Dominating ground cover did not affect regeneration (0.1-1.3 m) density or height increment in the virgin forest. Mortality rates were close to zero. Estimated time to grow through the size interval 0.1 to 1.3 m was 56 years. The recruitment rate into the lowest height class differed little between plots with high and low standing volume. Ingrowth into the tree layer was positively affected by decreasing standing volume.

Keywords

single-tree selection; selection system; shelterwood; virgin forest; advance growth; Picea abies; natural regeneration

Published in

Acta Universitatis Agriculturae Sueciae. Silvestria
2001, number: 209
ISBN: 91-576-6093-X
Publisher: Department of Silviculture, Swedish University of Agricultural Sciences

Authors' information

Nilson, Kristina
Swedish University of Agricultural Sciences, Department of Silviculture

UKÄ Subject classification

Forest Science

URI (permanent link to this page)

https://res.slu.se/id/publ/107992