Journal News Feed – SJFR Volume 29, Issue 8, 2014

The journal news feed presents the editors’ condensed summaries of key findings from selected scientific papers from SNS’ scientific journal Scandinavian Journal of Forest Research.

Journal news feed from Scandinavian Journal of Forest Research (SJFR) Volume 29, no rx Issue 8, 2014  reviews five new interesting new research articles. The topics range from seedling storage, browsing effects on pine, volume equation for lime trees to new technologies for forest thinning and thinning effect on aspen trees.

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Screening seedlings before storage reduces losses

Forest seedlings are often stored in freezers over winter. Measuring electrolyte leakage from the seedlings before storage is one way to screen whether they are hardy enough to survive this treatment. A study of Norway spruce and Scots pine seedlings showed that electrolyte leakage was a more reliable method than assessing dry matter content of the shoots, another established screening test. Seedlings with a leakage of 0-5 % are suitable for such storage, but seedlings with over 10 % leakage show low survival and poor growth after storage.

Read more in: Lindström et al. 2014. Storability measures of Norway spruce and Scots pine seedlings and assessment of post-storage vitality by measuring shoot electrolyte leakage. Scand  J For Res 29(8), 717-724.

First-year browsing is detrimental to pine

Herbivore browsing has strong effects on the growth, mortality and quality of pine trees. A long-term clipping study was used to estimate the effects of timing, duration and intensity of browsing, i.e. artificial clipping of shoots was meant to simulate damage caused by moose, deer or hare browsing. More intensive and more repeated clipping led to lower survival. Pines that were clipped in the first year were particularly sensitive – survival was only about 10 % compared to 90 % for the control group. Growth was most affected by clipping intensity – the more of the shoots that were removed, the less growth was recorded.

Read more in:Wallgren, M. et al. 2014. Effects of timing, duration and intensity of simulated browsing on Scots pine growth and stem quality. Scand J For Res 29(8), 734-746.

New technology is more efficient in young forest thinning

Thinning of young, dense forest stands can generate a resource for energy supply, but current harvesting methods are not always optimal. New technology is however being developed. Boom-corridor thinning techniques, bundle-harvesters and load compression devices can increase the efficiency of thinning of such stands. A model study showed that the cost could be reduced up to 15 % and the energy requirements by 21 %. Future technologies are particularly superior in dense stands with small trees – a common situation in Sweden.

Read more in: Bergström, D. & Di Fulvio, F. 2014. Comparison of the cost and energy efficiencies of present and future biomass supply systems for young dense forests. Scand J For Res 29(8), 793-812.

The lime finally gets its own volume equation

The small-leaved lime is an important tree species in Europe. Knowledge of the species’ growth and tree volumes is therefore important for forest management planning. Lime-tree volumes have, to date, been calculated using functions derived for beech.  In this article from the Czech Republic, a species-specific equation is presented. The new equation shows that the stem volume is actually larger than if the tree was estimated using the old beech equations.

Read more in Stolarikova, R. 2014. Comparison of tree volume equations for small-leaved lime (Tilia cordata Mill.) in Czech Republic. Scand J For Res 29(8), 757-763.

Thinning of hybrid aspen stands results in thicker stems

Hybrid aspen is a fast-growing tree used in many North-European countries. A Swedish study has measured the development of 16 stands over a whole rotation, lasting about 25 years. It showed that the average yield was 19.5 m3 per hectare and year, and the stands were still growing rapidly at 25 years. The study also showed that thinning had only a minor effect on the total volume production, but the stem volumes increased considerably.

Read more in: Rytter, L. & Stener, L-G. 2014. Growth and thinning effects during a rotation period of hybrid aspen in southern Sweden. Scand J For Res 29(8), 747-756.

Screening seedlings before storage reduces losses