Initial Density and Precommercial Thinning Affects the Development of Scots Pine Cultivations. : A Simulation Model for Combining Quantity and Quality : Modelling Regeneration Success and Early Growth of Forest Stands. Proceedings from the IUFRO Conference held in Copenhagen, 10-13 June 1996

Horsholm

1996

S. 285-297

30 Lit. Ang.

Bandaufführung

78886

A stand-level growth model for the early development of planted and seeded Scots pine (Pinus sylvestris L.) stands and a mixed linear model for the thickest living tree branch were developed. The models were used together with a function describing the lower limit of the living crown in order to determine the external quality of basal area median and dominant trees. The diameter of the thickest branch at the butt log, i.e. the first four meters above the ground, was used as the quality measure. Simulations showed that seeded stands always had a better quality than planted ones at the same density and site type. This was due to the slower development of dbh caused by grouped spacing before precommercial thinning. In seeded stands the timing of precommercial thinning had a rather small effect on branch diameter. Leaving a sufficient density, i.e. 3000-4000 stems ha hoch -1 in precommercial thinning, was found to be more important. High quality trees could be obtained from unthinned stands. The external quality of planted Scots pine stands seemed to be poor at the densities currently used in Fennoscandia. When the density was 2000 stems ha hoch -1 or less, the trees had very thick branches and were not even suitable for green pruning. When the density was 4000 stems ha hoch -1, the quality can be expected to be moderate on dryish or less fertile sites, but even then the green pruning must be made in two stages if high quality saw timber is the main aim. To obtain high quality saw timber from planted stands without green pruning, i.e. butt logs with a maximum branch diameter of 20 mm, central-European densities such as 10000 plants ha hoch -1 should be used.