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Severinsson, Thomas (2003) Höggallring i praktiskt skogsbruk. Other thesis, SLU.

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When Norway spruce is planted with large initial spacing and grows on highly productive sites in southern Sweden, a high proportion of the stems gets broad annual rings. The thinning programme carried out at the estate of Trolleholm aims to extract stems with too broad ring width. The 3-4 first thinnings are carried out as thinning from above, where only the thickest trees are removed. The internal distance may not fall below 5-7 meters depending on the number of thinning (short distance in young stands). The aim of this study was to examine the thinning model that is carried out at the estate of Trolleholm. A volume table is calculated to describe the model, and data is collected on temporary plots. Analysis on effect of tinning operations is carried out, and analyses are made to confirm that the thinning instructions are followed. The model has been applied since 1989, and the oldest stands have been thinned three times. The mean spacing between removed stems are 7,0 meters at the first thinning, 7,3 meters at the second thinning and 8,1 meters at the third thinning. The thinning grades according to stem number are 11%, 12% and 10% respectively, and the thinning grades according to basal area are 16%, 17% and 15% respectively. Considered extraction of trees from striproads the thinning grade is 24% both regarding to stem number and basal area. The thinning quotient is 1,3, 1,2 and 1,2 respectively. Considering extraction of trees from striproads the thinning quotient is 1,1 at the first thinning. In average the first thinning is carried out at the total age of 26 years, and the mean thinning interval is 4 years. The growth rate of the dominant height is lower compared to stands thinned from below according to Hägglund (1973). This might be an effect caused by thinning from above. Height development, basal area growth and volume production indicates that site index exceeds G36. The volume table fits the studied stands well. The total production of volume over bark is at the age of 36 years 432 m3/ha., and at this age the mean annual volume production is 12,0 m3/ha. The current annual increment in basal area and volume culminates before the age of 26 years. The number of stems after thinning is higher and the basal area after thinning is lower than recommended from authorities. The results show that the thinning instructions are being followed.

Item Type: Thesis (Other)
Keywords: höggallring, praktiskt skogsbruk, gallringsmodell, granskog, Trolleholms Gods
Subject (faculty): Faculty of Forest Sciences > Southern Swedish Forest Research Centre
Divisions: SLU > Faculty of Forest Sciences
Depositing User: Desiree Johansson
Date Deposited: 12 Mar 2007
Last Modified: 18 Aug 2015 09:48
URI: http://ex-epsilon.slu.se/id/eprint/1556

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