Wildfires

Wildfires are erasing Western forests. Climate change is making it permanent.

The trees were not coming back. In the years following the 2000 Walker Ranch Fire, grass and shrubs were regrowing in the charred foothills, but there were very few rare baby versions of the tall ponderosa pines that had dominated the area before the fire.

Now that the winter has cooled the 2021 fire season, scientists are looking at the big burn scars across the West with the grim understanding that, in some places, the pine and Douglas fir forests will not return.

The driving force here is that the rising global temperature is wiping out seedlings. In many spots around the U.S. West, summer temperatures are already high enough to cook young trees before they can develop thick protective bark. Others have become so dry that seedlings shrivel before their roots can grow deep enough to reach groundwater. Both circumstances can thwart forest regeneration. Mature trees can survive in these areas long after they stop reproducing. But when fires wipe out these forests and seedings can’t get a foothold, they are replaced with grasses and dense brush.

Climate change has already shifted biomes. Intense fires simply clear away the last vestiges of the old regime.

from WordPress https://ift.tt/3d91KDa