Climate change may bring about nonnative species in post-fire forests

Range shifts could affect how the ecosystem recovers

CHICO » The Camp Fire may be accelerating changes in the local environment brought about by rising temperatures from increased greenhouse gas emissions.

One of the widely recognized phenomenons of climate change is the displacement of lower-elevation species to higher elevations after a rise in temperatures. It’s called a range shift and it’s been happening slowly over the past decades in California, with very different effects depending on each precise location’s micro-climate.

In Butte County, the major disturbance caused by the Camp Fire is opening the door for those changes to happen faster. Local scientists are monitoring what species are recovering and considering what species will be best suited for an era of higher temperatures. The changes in the local ecosystem matter not only because they may affect the risk for more fires in the future, but because they may alter important services like water quality, pollination and biodiversity.

“I’m trying to think, with climate change, what species are suitable for reforestation, revegetation within the landscape. I’m trying to envision what the next 200 years look like,” said Don Hankins, a professor of geography and planning at Chico State specializing in fire ecology. “Some of the species that have existed in Paradise were really more of a relic.”

The range shifts will happen over many years. In the short term, many oaks are able to regrow from the trunk even if the canopy has been killed; most conifers, if torched, can only grow back from a seed bank. Invasive and nonnative species often thrive in post

fire environments. Though it’s still early to make conclusions about what the environment will look like after the fire long term, many of the areas that have been burned in Butte County already look different. In Concow, seedlings and brushes, including invasive species like star thistle, are starting to grow back from mostly bare hillsides. The area recently burned by the Swedes Fire has seen grasses, especially nonnative grasses like wild oats, gradually replace oak woodlands after frequent, repeated fires in the past 10 years.

Looking forward, Butte County could see more

changes.

A 2017 study from the UC Davis modeling how different emissions scenarios would play out in California’s different ecosystems found that the Sierra foothills in Northern California was the area at most risk for stress from climate change in the state, along with the Sonoran Desert. That means many species could adapt by migrating northwards and upslope. Scientists have found that ponderosa pines have already been moving up in elevation on the western side of the Sierra Nevada.

Lowering emissions would reduce but not eliminate the climatic stress, which is already contributing to tree mortality.

Hankins points to a spot in Big Chico Creek Ecological Preserve as an example.

There are some firs and pines mixed in with the oak woodland, even though conifers are not expected to be there based on the elevation, said Hankins.

He’s having to consider whether keeping the firs around is just a “fantasy.” During the drought, bark beetles caused more of the conifers to die. Drought conditions are expected to increase in California under climate change models.

“If the climate is not suitable to the trees there at that point, they’ll be more vulnerable,” he said. “Does it make sense for these to be here?”

On the ridge, he suggested that black oaks will likely be one of the better bets for a species that will survive future fires and be healthy in higher temperatures.