Last winter's cold temperatures did kill some mountain pine beetles in Alberta, but it wasn't enough to reduce the threat of additional infestations, according to recent field surveys.

"These results show we need more than cold winters to be successful in our fight against pine beetles in our forests, " Sustainable Resource Development Minister Ted Morton said Tuesday in a release.

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Field surveys indicate last winter's cold temperatures weren't enough to reduce the threat of additional infestations of the mountain pine beetle in Alberta. (CBC)

The province will continue with single-tree removals, stand-level harvest and controlled fires, Morton said.

Alberta's attack against pine beetles is focused in southwest Alberta, and on the eastern edge of the infestation.

The objective is to minimize the spread of beetles north and south along the eastern slopes, and to prevent beetles from spreading east in the boreal forest.

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The mountain pine beetle continues to infest Alberta forests despite cold temperatures last winter. (CBC)

Preventing the spread of infestations protects the health of forests and the values they provide to Albertans such as watershed hydrology, fish and wildlife habitat, recreational opportunities and forest industry employment, the release states.

The surveys, conducted at 217 sites in the province's pine forests, involved taking several core samples from 1,380 individual trees and counting the number of living and dead pine beetles under the bark.

Mountain pine beetles threaten the health of six million hectares of pine forest in Alberta, the release states.

Infestations began in southwest Alberta in 2002 and in west-central Alberta in 2006.