Mills in the heart of Canada's timber industry have fallen quieter this winter as wildfires and infestations made worse by climate change have made vast tracts of once valuable forest into barren stands of dead trees.

The latest tally of beetle kill shows more than 550,000 acres of forest with dead spruce from the ongoing infestation this year alone, much of it in Mat-Su.

Over the last two years, an outbreak has affected more than 500,000 acres of forest.

Dead, red trees signal an increasingly dire outbreak driven by warm summers and plentiful spruce, especially in the Susitna Valley.

Beetles that killed millions of acres of trees in the 1990s were a first sign of climate change. In a new flare-up, they continue marching north as Alaska warms.

The closures of the campgrounds, facing the threat of falling trees, likely will last through summer, the state parks division said.