Oregon State University has released a new study that says climate change, insect attacks, diseases and fire are causing huge migration of trees across the West.
Researchers looked at how 15 species of conifer trees are already migrating, and they predict what the forests of the future climate will look like.
“The forests of our future are going to look quite different,” said Richard Waring, professor emeritus at OSU and lead author of the study. “We can’t predict exactly which tree (species) will die or which one will take its place, but we can see the long-term trends and probabilities.”
As a changing climate shifts temperature and precipitation patterns across the West, his study concluded, trees that once were able to survive in certain environments will lose ground to other species that survive better in the new climate.
In some areas, that will mean lodgepole pine is replaced by different trees such as ponderosa pine or Douglas fir. In others, forests may turn to grass savannah or sagebrush desert. More than half the species currently living in central California won’t survive in the future climate, researchers concluded.
“Some of these changes are already happening, pretty fast and in some huge areas,” Waring. “In some cases the mechanism of change is fire or insect attack, in others it’s simply drought.
Among the findings:
- The northern and southern extremes of the study area – in British Columbia and California – will see the greatest shifts.
- Lodgepole pine and Engelmann spruce are expected to decline while Douglas fir and western hemlock may expand.
- Mild, wet areas of western Oregon and Washington will face less species change than places with harsher climates.
- More than half of the 15 evergreen species studied are losing their competitive edge in six eco-regions.
- Climate changes are making conditions more favorable for outbreaks of disease and insects.
- Climate warming will spur growth at higher elevations and latitudes and drought at the other extreme.
- Fire will occur more frequently as the climate changes.
What can we do about all this?
I’ve written about a separate study showing thinning forests reduces the impact of wildfire. But Waring said climate change will even change the degree to which that strategy will work.
“There’s not a lot we can do to really control these changes,” Waring said. “For instance, to keep old trees alive during drought or insect attacks that they are no longer able to deal with, you might have to thin the forest and remove up to half the trees. These are very powerful forces at work.”
Researchers said one of the best approaches to plan ahead for these changes is to make sure corridors of habitat stay intact so tree species can migrate to new areas as the climate changes.