Outbreaks of defoliating geometrid moths have damaged thousands of square kilometres of mountain birch forest in northern Scandinavia during the last two decades. Salvage logging of damaged mountain birch stands has been discussed as a means of speeding up the regeneration of the forest.
In the present study COAT researchers, Vindstad and colleagues, in collaboration with the county governor of Finnmark and the Finnmark estate agency, provide the first experimental test of the effects of logging in damaged mountain birch forest. The study shows that logging does indeed stimulate the production of basal sprouts, with the average number of sprouts in experimental logging plots being four times higher than in untreated controls two year after logging. In one out of two experimental regions, logging also improved sprout growth, and sprouts were starting to grow into new stems only two years after logging. However, in the second experimental region, sprout growth was retarded by ungulate browsing, to the extent that stem production failed completely. The production of sprouts and stems was also limited on rich soils, dominated by single-stemmed birches that have low capacity for sprout production.
The results suggest that logging is a viable option for improving forest recovery in areas where ungulates are scarce, but is probably not worthwhile where ungulates are abundant. Also, logging should be practiced with care on rich soils, where birches have low capacity for sprouting.
Further reading:
Full paper: http://www.sciencedirect.com/science/article/pii/S0378112717305194
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| An experimental plot two years after logging. The red poles mark the location of birch trees that have been cut down. Photo: Moritz Klinghardt |
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| | An experimental birch stump two years after logging, showing extensive production of basal sprouts. The red pole is 50 cm high. Photo: Moritz Klinghardt | |