Quality and yield of pulpwood in drained peatland forests: pulpwood properties of Scots pine in stands of first commercial thinnings

Abstract

The inherent structural dynamics of drained peatland forests may result in a great variation in various wood and fi ber properties. We examined variation in fi ber and pulp properties i) among stands, ii) among trees within stands, and iii) within trees in young stands dominated by Scots pine (Pinus sylvestris L.). The stands, selected to cover a maximal range of the potential variation, were all at a stage of development where the fi rst commercial thinnings would be feasible. Differences in the processability of the thinning removals were small. In similar kraft cooking conditions, a 5-unit variation in the kappa number of unbleached pulp was observed among the stands. Stand origin had no effect on pulp bleaching. The wood formed prior to drainage had a higher density, shorter fi bers, was slightly slower delignifi ed by cooking, and its yield was slightly lower than that of post-drainage wood. These properties, except for high density, are typical for juvenile wood in general, and at stand level they did not correlate with the proportion of pre-drainage wood. When the variation in fi ber and pulp properties was broken down into its components, most of it was derived from tree-level in all the cases. On average, the fi ber and pulp properties did not differ from those observed for fi rst-thinning pulpwood from upland sites. Consequently, peatland-grown pulpwood may be mixed with other pulpwood in industrial processes. It would probably be best suited as the raw material for pulps with high bonding requirements, e.g. in the top ply of multi-ply board grades or in some specialty grades.

Variations in fiber length within a first-thinning Scots pine (Pinus sylvestris) stem

“…1) shows the change in the distribution in one selected sapwood growth ring in the longitudinal direction of the stem. As expected (Varhimo et al 2003), the average fiber length first increased from the butt of the stem to an average stem height of 2 m and then decreased towards the stem top with a simultaneous decrease in the narrowness of the distribution.…”

“…0.469 (R 2 = 0.974). Varhimo et al (2003) have reported that the variation in pulp yield within trees contributes about two-thirds of the total variation, the remaining one-third owing to the variation between trees. 6 0,8 1,0 1,2 1,4 1,6 1,8 2,0 2,2 2,4 2,6 2,8 3,0 3,2 Fiber length (mm) Relative height of stem (%) Fig.…”

“…According to Varhimo et al (2003) the total variation in fiber length, coarseness, and pulp yield is much larger within a single tree (the contribution of variation from 73 to 83%) than between similar trees (ranged from 17 to 24%). The variation within a stem is caused by the characteristics of the growth meristems, which produce different kinds of fibers dependent on age and the different periods in the growth season.…”

Predicting wood and tracheid properties of Scots pine

“…The experiments are described in detail in Varhimo et al (2003). In both experiments, two unthinned control plots and two heavily thinned plots, adjusted according to the Finnish guidelines for forestry practice (Hyvän metsänhoidon suositukset, 2006), were sampled.…”

Impacts of different thinning regimes on the yield of uneven-structured Scots pine stands on drained peatland

“…The study was part of a project called "Quality and Yield of Pulpwood in Drained Peatland Forests", which was aimed at quantifying the variation in wood, fibre and pulp properties (Varhimo et al 2003, Rissanen 2003 and yield in peatland stands, and at evaluating the relevance of the current guidelines for silviculture on drained peatland sites regarding their production potential and/or the quality of wood produced.…”