Last winter’s record-high vole populations are about to collapse in the Southern and Central Finland, where voles have of late been causing considerable damage to sapling stands.
According to the Finnish Forest Research Institute (METLA), there are at least 18,000 hectares of completely destroyed sapling stands in the south of Finland.
The area of sapling stands that have sustained partial damages is several times larger.
The most devastation the voles caused in the provinces of Northern and Southern Savo, Central Finland, Pirkanmaa, Häme, and Uusimaa.
In many places the vole densities measured by METLA were highest during the organisation’s 30-year history.
The vole and mole populations appear in cycles, so the ongoing collapse was only to be expected.
The populations are predicted to remain low until the spring of 2010. Then, in the summer of 2010 they will start expanding again. The following winter the tree saplings will once again be in danger.
The next vole population peak is predicted for the autumn of 2011. Damages to tree saplings are expected to be severe during the winter to follow.
METLA has therefore issued a recommendation for forest owners thinking of carrying out final fellings to time the planting of new saplings for the spring of 2012.
That is when the next anticipated population collapse of the little critters will take place.
