Erik Valinger

Modelling probability of snow and wind damage in Scots pine stands using tree characteristics

Abstract Predictions of damage risk from snow and wind at sites using tree characteristics of Scots pine ( Pinus sylvestris L.), were made using a subset of data from permanent sample plots within the Swedish National Forest Inventory (NFI). The plots were sampled twice at five-year intervals between 1983 and 1992. A logistic risk assessment model was developed using data originating from 286 plots, dominated by Scots pine (> 65% of basal area), within one county situated in the boreal zone in northern Sweden (Vasterbotten). The model was evaluated with NFI-data from two other counties, one adjacent to Vasterbotten (Vastermorrland, 99 plots), which is also in the boreal zone, and one (Kalmar, 138 plots) in the hemi-boreal zone in southern Sweden. In each plot, measurements at first inventory of tree characteristics for the largest undamaged sample tree, and measurements at second inventory of damage from snow and wind on all sample trees were used to develop a logistic model that predicts the damage probability for each site. The best predictors were upper diameter ( ud , diameter at 3 or 5 m) and the ratio of height/diameter at breast height ( rhd ). According to the model calculations, the overall damage probability never exceeded 0.26 for any of the sample plots used for model development. At a given ud the probability of damage is higher for a site with trees of low rhd . The fit of the model was better for the adjacent Vasternorrland county than for the southern county, Kalmar. This inferior predictability was explained by differences in tree characteristics between Kalmar and the other counties. The results show that it is possible to predict damage from snow and wind at a site by using only single tree characteristics.

Effects of thinning and nitrogen fertilization on stem growth and stem form of Pinus sylvestris trees

The effects of thinning and fertilization, both singly and in combination, on the growth of 45 year old Pinus sylvestris trees, were studied in northern Sweden for five years after treatment. Based upon annual examination of trees for height and diameter growths, the radial, height and volume increments of the stems in relation to treatments were estimated. Thinning was found to increase stem radial growth after one year, while increased growth after fertilization appeared the second year. Thinning promoted lower bole growth, while fertilization increased upper bole growth. Thinning decreased height growth and fertilization increased height growth in the first year with associated increased volume increment. An increased volume growth for thinned trees was not found until the third year after treatment. Neither treatment caused changes in the length of the seasonal growth response or in the phenology of growth.

Twelve-year growth response of Scots pine to thinning and nitrogen fertilisation

Effects of thinning and nitrogen fertilisation, singly and in combination, on growth of 56-year-old Scots pine (Pinus sylvestris L.) trees in northern Sweden were examined for the 12 years after treatment. The response to treatments was measured as dry weight biomass change in above and below ground components over the 12 years and as four-year period changes in relative radial, height, and volume growth under bark. Results were expressed in terms of average tree and as a stand total. During the 12-year period following treatment, biomass production per tree was increased in all fractions by thinning, but only for shoot axes and crown biomass by fertilisation. In the first four-year period after treatment both thinning and fertilisation gave a positive response in radial and volume growth. The response to fertilisation in radial and volume growth faded out after eight years, although a positive effect after thinning could still be seen after 12 years. Height growth was not affected by treatments. In comparison to the control, volume production per hectare decreased by 37% after thinning singly, 10% after the combined treatment, and increased by 20% after fertilisation. The results are discussed in terms of nitrogen availability, light competition, and needle efficiency.

Effects of wind sway on stem form and crown development of Scots pine (Pinus sylvestris L.)

Summary The distribution of growth was examined in 45-year-old Scots pine (Pinus sylvestris L.) trees stayed with wires attached at 30% and at 30% and 60% of the tree height, and in trees with a metal sail attached in the top of the crown. The treatments commenced in 1983 and 16 trees per treatment, including the control, were sampled in 1988. Increments of stem diameter, height, and volume in treated and control trees were estimated from stem and branch mensuration. Staying the trees promoted radial growth by about 10% above the point of attachment. Increasing the wind sway with sails promoted radial growth below the crown. Changes in the distribution of growth within the crown were not as obvious as the changes along the stem below the crown.

Effects of Fertilization and Thinning on Heartwood Area, Sapwood Area and Growth in Scots Pine

In a fertilization and thinning experiment on Pinus sylvestris L. situated in northern Sweden, the effects on the amount of heartwood and sapwood were examined 12 yrs after treatment. On stem discs taken from the stump up to 75% of tree height, age, diameter, heartwood diameter and growth rings included in the heartwood were measured. Increases in heartwood area following fertilization and thinning were not statistically significant, whereas sapwood area was significantly increased by both fertilization and thinning. There was a significant positive interaction effect of fertilization and thinning on diameter under bark, sapwood area and relative heartwood area. The number of growth rings included in the heartwood at breast height was not affected by treatments. Thinned trees showed a higher needle biomass per unit of sapwood area at breast height. The results show that the possibility of affecting the amount of heartwood in individual trees by thinning and fertilization is limited. The results are discus...

Wind and snow damage in a thinning and fertilisation experiment in Pinus sylvestris

Damage induced by wind and snow was examined in an experimental series with thinning and fertilisation established in 34–58 years old Scots pine (Pinus sylvestris L.) stands in northern Sweden during the period 1969–83. The experiment contained six treatments and 23 replications. The treatments were 25% and 60% thinning from below, 25% thinning from above, 30% thinning from below combined with N and NP fertilisation. Percentages represent basal area harvested at the first thinning. Differences in damage level were examined at the first reinventory, 4–8 years after thinning. The level of wind and snow‐induced damage was about 1% of the basal area during the period studied. Proportion of basal area damaged was not affected by the treatments, but there was more snow damage after thinning from above than after thinning from below. The proportion of trees damaged by snow and the proportion of dead trees were affected by treatment. The densest stands, the control and 25% thinning from above, were damaged the mo...

Conducting sustainability impact assessments of forestry-wood chains: examples of ToSIA applications

Within the EFORWOOD project, new methodological approaches to assess the sustainability impacts of forestry-wood chains (FWC) were developed by using indicators of environmental, social and economic relevance. This paper introduces and discusses the developed approach and the two main products developed in the EFORWOOD project: the Database Client and the Tool for Sustainability Impact Assessment (ToSIA), which hold, calculate and integrate the extensive information and data collected. Sustainability impact assessment (SIA) of FWCs is based on measuring and analysing environmental, economic and social indicators for all of the production processes along the value chain. The adoption of the method varies between applications and depends on the specification of the FWC in the assessment and what questions are studied. ToSIA is very flexible and can apply forest-, product-, industry- and consumer-defined perspectives. Each perspective influences the focus of the analysis and affects system boundaries. ToSIA can assess forest value chains in different geographical regions covering local, regional, national and up to the continental scale. Potential issues and scenarios can be analysed with the tool including, for example, the impacts of different forest policies on the sustainability of an FWC. This paper presents how ToSIA can be applied to solve such diverse problems and underlines this with examples from different case studies. Differences in chain set-up, system boundaries and data requirements are highlighted and experiences with the implementation of the sustainability impact assessment methods are discussed. The EFORWOOD case studies offer valuable reference data for future sustainability assessments.

Modelling probability of snow and wind damage using tree, stand, and site characteristics from Pinus sylvestris sample plots

The risk of damage on trees from snow and wind was modelled using tree, stand, and site characteristics from 286 permanent Scots pine (Pinus sylvestris L.) sample plots within the Swedish National Forest Inventory. Three logistic risk assessment models were developed for the county of Vasterbotten in the boreal zone of Sweden. The best model, using tree, stand, and site variables, correctly classified 81.1% of the undamaged and 81.8% of the damaged plots. The model over‐predicted the proportion of damaged plots (21.3%), compared to the observed proportion of 3.8%. When evaluating the models using temporary plots from Vasterbotten, the model using tree, stand, and site variables showed the best overall predictability. When applied in southern Sweden, the models developed for Vasterbotten showed poor predictability. The study shows possibilities for correctly classifying the overall susceptibility to damage from snow and wind if the models are used within their limits.

Mechanical stress during dormancy stimulates stem growth of Scots pine seedlings

Abstract The effects of mechanical stress imposed during dormancy on stem growth were examined in 5-year-old Scots pine ( Pinus sylvestris L.) seedlings. The treatments were different degrees of manual bending, which were executed in freezing-storage (−6°C). After thawing, seedlings were reactivated and grown in a climate chamber for 8 weeks. Bending promoted a statistically significant increase in xylem width at the point of bending, but had no effect on tracheid width, indicating that the increase in xylem width was caused by a faster rate of tracheid production. The results show that Scots pine seedlings record mechanical stress during their dormant period, and respond to this during the following growth period. The ecological and silvicultural significance of this response is breifly discussed.

Damage to Residual Stand Caused by Mechanized Selection Harvest in Uneven- Aged Picea abies Dominated Stands

(L.) Karst) dominated stands in west-central Sweden. The objective was to quantify level and type of damage caused by harvesting and to quantify the difference between two treatments: T20) only skid road harvest (20 m distance between ca. 4 m wide roads), and T40) skid road harvest (40 m distance between ca. 4 m wide roads) combined with thinning between the roads. In T40, the goal was to harvest approximately the same standing volume as in T20. After harvest, two circular sample plots (radius 18 m, i.e. 1018 m