Even if they remain forests, the type of forest will be very different in the western part of the country, scientists say.
As the climate changes, plenty of flora and fauna are having a hard time keeping up. This means that some species will lose out while others will thrive in warmer temperatures.
These changes are already taking place in forests in the western part of the United States where trees better able to tolerate stresses from heatwaves and droughts are becoming increasingly dominant.
Many local trees are becoming “mismatched with their environment,” which means these trees “are more likely to die or be susceptible to fire or insect infestations,” according to scientists from the University of California at Berkeley and the U.S. Forest Service who have just published a new study on their findings.
The researchers analyzed the composition of some 50,000 forest plots in western states of the country over the past decade and will continue to monitor them. They also mapped localized climate change data in tandem with their data on the composition of trees in studied areas.
They have found that trees with a greater tolerance for increasing temperatures and dryer conditions such as the California juniper are becoming more widespread, albeit climate change is outpacing those adaptations in local forests.
Worryingly, says Kyle Rosenblad, a Ph.D. candidate and lead author of the study, the ratio of trees is shifting with established species that prefer colder and wetter conditions such as the Douglas fir succumbing to the new climatic conditions. They are also falling prey to insects in their weakened state.
These changes mean that local forests could undergo “vast ecological changes” in coming decades, the scientists warn. “Places that are forested today may only be able to support grassland,” Rosenblad explains. “Try as we might, we may not be able to stop that.”
The changes will also undermine the carbon storage capacity of local forests. There are more than 32 million acres of old-growth forests on public lands around the United States, and mature trees are particularly good at storing large amounts of carbon.
However, in addition to logging, “rampant wildfires and beetle infestations have decimated millions of acres of trees, and driven in part by rising temperatures,” the researchers note.
“Even if they remain forests, the type of forest will be very different,” Rosenblad says. “So for the people and animals who depend on these forests, this is going to be a drastic change and we need to start thinking about how we will adapt.”