What all those dead trees mean for the Sierra Nevada

Research ecologist Nathan L. Stephenson looks over a dead ponderosa pine in Sequoia National Park.

Ecologist Adrian Das inspects the paths of bark beetles that led to the death of a white fir tree in a plot of land that ecologists have been studying since 1992 in the Sequoia National Park.

Swaths of dead conifers on the ridgeline have succumbed to drought and disease in Sequoia National Park.

The needles of a dead sugar pine tree have gone from green to orange as the trees succumb to drought and disease in Sequoia National Park.

Ecologists Nathan L. Stephenson, left, and Adrian Das, both with the U.S. Geological Survey, walk past living and dead trees in a plot of land that has been studied by ecologists since 1992.

A dead pine tree stands against a backdrop of dead conifers, in orange, and living trees in Sequoia National Park.

A mule deer makes its way through the Sequoia National Park.

Haze settles over the Sequoia National Park and the community of Three Rivers in December.