Ane Zubizarreta-Gerendiain

Differences in branch characteristics of Scots pine (Pinus sylvestris L.) genetic entries grown at different spacing

Abstract• We studied the differences in branch characteristics along the stems of six different genetic entries of 20 year old Scots pines (Pinus sylvestris L.) grown at different spacing (current stand density range 2000–4000 trees ha−1) in central Finland. Furthermore, we studied the phenotypic correlations between yield, wood density traits and branch characteristics. All the genetic entries had Kanerva pine (plus tree S1101) as a father tree, whereas the mother tree represented Finnish plus trees from southern, central and northern Finland.• Spacing affected all yield traits, wood density and living branch characteristics such as relative average branch diameter and relative cumulative branch area (p < 0.05). As a comparison, genetic entry affected height, while origin group (southern, central and northern ones) affected most of the studied traits. Regardless of spacing, the northern origin had, on average, the largest stem diameter and highest wood density, while the central one was the tallest one. Furthermore, average branch diameter along the stem was affected by branch age, origin group and spacing, while average branch angle was affected by branch age and genetic entry (p < 0.05).• In general the average branch size could be decreased especially in lower tree canopy by denser spacing during the early phase of the rotation, but only at the expense of tree growth. Correspondingly differences between origins are mainly related to their differences in stem growth.

Effects of climate change on optimised stand management in the boreal forests of central Finland

In boreal conditions, climate change is expected to increase mean annual temperature and precipitation, increasing forest growth and productivity in managed forests. In this study, we aimed at finding out how climate change affects the optimal management of Scots pine-, Norway spruce- and silver birch-dominated stands on sites of varying fertility (high-herb, mesic and sub-xeric sites) in the boreal forests of central Finland. The objective function was to maximise net present value (NPV), considering the future incomes from timber sales and costs of forest operations. The results showed that under the gradually changing climate, the optimised management schedules differed from those observed under the current climate. In Norway spruce- and birch-dominated stands, cuttings were done earlier under the changing climate than under the current climate, while in Scots pine-dominated stands they were delayed under the changing climate. The optimised management schedules also varied, depending on tree species and site fertility types. Under the changing climate, both timber production and NPV increased compared to the current climate, regardless of species and site fertility type.

Effects of spacing and genetic entry on radial growth and ring density development in Scots pine (Pinus sylvestris L.)

Abstract• IntroductionThe objective of this work was to study how spacing and genetic entry and/or origin group affect radial growth (ring width and cumulative diameter development) and ring density from pith to bark in Scots pine (Pinus sylvestris L.) and in what sense their annual variability could be explained by the climatic variables. The spacing trial was located in central Finland, with current stand density range of 2,000–4,000 trees per hectare. All the six genetic entries had Kanerva pine (plus tree S1101) as a father tree, whereas the mother tree represented Finnish plus trees from southern, central and northern Finland.• MethodsIn the early phase of the stand development, no significant differences (p < 0.05) were found for mean ring width (RW), cumulative diameter (Dt1) and mean ring density (RD) development between different spacing and/or origin groups (southern, central and northern ones).• ResultsBoth cambial age and spacing affected RW and RD development from pith to bark. In addition, RD development was affected by the origin group (OG), unlike RW. The annual radial growth also decreased slightly earlier and much faster in the narrowest spacing.• ConclusionThe annual variation in RW could not be explained by the climatic factors considered (e.g. temperature sum during the growing season or June and/or July mean temperature). However, the mean temperature for current June and the temperature sum during the current growing season partly explained the annual variation in RD (p < 0.05).