Climate: Forests and Fire

Warm summers and periodic forest fires are natural parts of the Crown of the Continent Ecosystem. But our warmer, drier climate is changing that as well. Canadian ecologist J. Pojar and other scientists have established baseline date showing the following, over the last 30 years:

• The average wildfire season has grown by 78 days.

• The number of large fires has grown four-fold.

• The average number of acres burned each year has grown six-fold.

Pine beetles and other insects are no longer limited by deep winter freezes. In recent decades, bark beetles have eaten through 10.1 million acres of lodgepole pine in British Columbia, five million acres more in Montana. Foresters and ecologists have documented other changes as well, as entire ecosystems reorganize into unfamiliar arrangements. Scientists such as Philip Van Mantgem of the Western Ecological Research Center have determined forests already are shifting quickly.

• Summertime droughts appear to trigger waves of dead Western pine and fir forests;

• British Columbia’s iconic trembling aspens are likewise dying back.

• Trees are encroaching on sub-alpine meadows as trees survive where it was previously too cold. Likewise, trees are encroaching on former grassy and shrubby areas favored as big game winter range.

By 2050, some scientists expect an additional 175 percent increase in the area burned by wildfire each year in the Rocky Mountains.