How to Redesign a Forest: Restoring California's Trees in the Age of Fire
Oct 7, 2020 at 7:00am
Last spring, a tree-planting crew hiked into the hills near Paradise, California, to take on a challenge: What’s the best way to replant a forest when it’s very likely that it could burn again?
So far in 2020, more than 4 million acres have burned in California—an area roughly the size of Connecticut. It’s a record-breaking amount. It’s also a continuation of a long-term trend: Combine climate change that makes the state hotter and drier with decades of fire suppression, and megafires are becoming more common. The Camp Fire, which burned through Paradise in 2018, killing 85 people and leveling thousands of homes, was one of a series of fires in the area. This year, as fires raged nearby, people living there were forced to evacuate again.
As wildfires get bigger, they destroy everything in their path, which makes it harder for forests to grow back once they pass. Without intervention, some burned forests could turn into shrubby grasslands. “The fires are coming back so frequently, and they burn so hot, that they take out all the mature, seed-bearing trees,” says Austin Rempel, senior manager of forest restoration at the nonprofit American Forests. “There just isn’t a source of seed for trees to come back after fire. What fills the gaps is the grasses and shrubs. We’re basically talking about semipermanent forest loss.”
That’s a problem not only for the ecosystem, but also for climate goals: Trees are very effective at sucking up carbon dioxide (CO2) and storing it as they grow. In California, preserving forests is part of the state’s cap-and-trade system. Globally, forests are necessary to reach net-zero emissions. But replanting after a fire isn’t as obvious a benefit if the new trees just risk going up in smoke.
A different approach to planting, though, can reduce that risk. In some cases, that involves fixing past mistakes. Traditionally, planted forests looked like rows of crops, in what Rempel says was called the “pines and lines” model. The trees were planted close together to shade the ground so shrubs wouldn’t grow, with the idea that someone would come back a decade later to thin out the trees. But the Forest Service and other forest managers often haven’t had the resources to do that, leaving trees closely bunched together. “The trees can burn really easily because the fire just passes from treetop to treetop, so they can take out your entire planting project in one fell swoop,” Rempel says.