Wildflowers after wildfires
It’s a scenario repeated often in fire-prone California.
A disastrous blaze sweeps through a mountain valley, scorching pine forest and blackening oaks. In its aftermath, ash and charcoal from the burned trees carpet the forest floor. Where branches once blocked the sun, intense bright light streams down on the shadeless slopes as plant life slowly peeks through the destruction.
Winter rains wash away some of the soot and soak nutrients down into the sandy soil. Then comes the miracle: a rainbow of wildflowers.
That’s California’s cycle of life.
“It’s almost inevitable to see wildflowers after wildfires,” said longtime native plant expert and author Chet Blackburn of Auburn. “We have fires, a good rainy season, and then wildflowers just burst into bloom.”
During a smoky summer when fire danger is extreme, it’s a small consolation. Reminders of our state’s precarious flammability filled the air this past week as smoke from wildfires in Monterey County drifted into the Central Valley. Another massive wildfire torched several square miles near Santa Clarita just north of Los Angeles.
While incredibly destructive and expensive to fight, fire also can rejuvenate California’s native landscapes. Renewal by fire is built into many native plants’ DNA. Several plants need high heat or smoke exposure to sprout seeds, particularly those native to chaparral or shrub land. Some pine cones must be exposed to fire to spring loose their seeds.
Nature has its own system of checks and balances, scientists say. Fire burns off natural oils and secretions from shrubs that block competition from other plants. Clearing away old growth, fire in turn increases the diversity of chaparral plants. Likewise, fire can rejuvenate forests, too, putting nutrients back into the soil to stimulate new growth.
Generally, it’s the annuals that put on the brightest post-fire flower show, experts say. No longer shaded in the forest’s understory, golden daisies glow in the extra sunlight. Indian paintbrush and scarlet larkspur offer splashes of vivid red. Pink lupines and purple penstemons bloom in abundance.
Those flowers were always present but unseen, their seed waiting in the soil for the right opportunity.
“Some of the seeds stay in the ground for years and years before it’s stimulated by fire,” said Blackburn, past president of the Redbud Chapter of the California Native Plant Society.
Intense heat breaks down their seed coats or other inhibitors and allows the seeds to sprout.
Several native shrubs and trees will regrow after fire, too. They form a basal burl underground that remains viable through fire. This specialized root structure is common among chaparral’s larger plants and allows California shrub lands to bounce back rapidly after disaster.
Likewise, several California oak species also re-sprout, usually at the base, although the process may take decades.
This year’s wildflower season got another boost unrelated to flame. Throughout California, many drought-parched native plants are responding to a relatively wet and normal winter.
“This has been a really good year for wildflowers in general,” said Blackburn, co-author of “Trees and Shrubs of Nevada and Placer Counties, California” (CNPS, 529 pages, $34.95). “The rainfall wasn’t all that great, but it was evenly spaced. I found things blooming on my property that I hadn’t seen in five years.”
Annuals in particular have bloomed profusely due to the rain, but so too have some fussy native bulbs and shrubs.
“The drought kept the green parts of bulbs – their foliage – from storing enough energy to actually produce flowers,” Blackburn explained. “Now, they can bloom.”
Personally, I saw this post-fire model play out in Green Valley Lake, a resort area in Southern California’s San Bernardino National Forest about 100 miles southeast of Los Angeles where my family has had a cabin since 1928.
In October 2007, the Slide Fire torched nearly 13,000 acres in and around Green Valley Lake, destroying 272 cabins and other structures. (Fortunately, our cabin was spared.) Thousands of pines, firs and other trees were charred.
After the fire, the burn zone looked like a lifeless moonscape, covered with gray ash and blackened limbs. It was one blaze out of 30 that made up a devastating firestorm. Whipped by vicious winds, those wildfires engulfed nearly 1 million acres in Southern California’s wilderness areas between Labor Day and Thanksgiving that year.
Nearly nine years later, reminders of the Slide Fire still dot Green Valley. Like blackened monuments, scores of charred tree trunks stand in place in the back country along hiking trails. Stripped of their bark and weathered to a metallic sheen, huge logs lie where they fell during the blaze.
But many of the surrounding trees have grown back or recovered from the intense heat. Under the silver skeletons of their former branches, California black oaks regrow from their roots, forming new groves to replace the old.
Where once there were only pines, flowering shrubs now cover the former forest floor, attracting bees and birds. Enjoying some sunshine, wild roses flourish along creek beds or shallows where rain collects. Peeking out from around logs and boulders, bunches of lupines, penstemons and other mountain wildflowers brighten the landscape with sweet-smelling blooms. Wild irises punctuate the shade under pines with bold dots of purple.
It’s a lesson in patience as well as botany. The forest will come back after fire, but it takes time – and a little rain.