Mapping California’s ‘Zombie’ Forests

Zombie Forest Map - Source: The Global Ecology and Climate Solutions Lab at the Stanford Woods Institute for the Environment, using data from the U.S. Forest Service’s Wieslander Survey and Existing Vegetation maps. Note: The data looks at changes in conifer forests across the Sierra Nevada between the 1930s and the 2010s.

Mapping California’s ‘Zombie’ Forests
The New York Times, March 6, 2023
By Elena Shao

“In California’s ‘zombie’ forests, conifers have become mismatched to a warming climate.”


A warming climate has left a fifth of the conifer forests that blanket California’s Sierra Nevada stranded in habitats that no longer suit them, according to a study published last week by researchers at Stanford University.


In these “zombie forests,” older, well-established trees — including ponderosa pines, Douglas firs and sugar pines — still tower overhead, but few young trees have been able to take root because the climate has become too warm and dry for them to thrive.


Zombie forests are “cheating death, in a way,” said Avery Hill, an ecologist and the study’s lead author.


Mature trees are able to survive even after their local climate has shifted, but the species is not likely to grow back in these areas after a major disturbance, like a catastrophic wildfire, logging event or period of extreme drought. Instead, the study found, the forest is more likely to be replaced by smaller, shrublike vegetation that is adapted to warmer, drier conditions.

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About the Author:

Elena Shao is a reporter and graphics editor based in New York. She was previously a reporting fellow on the Climate desk.