Intense heat from fire allows unusual native plants to
flourish
It’s too bad the land ravaged in the Croy fire is all privately owned; it makes for a great hike and an even better ecology field trip.
Two and half years after a wildfire blazed through the Croy and Eastman canyons west of Morgan Hill, engulfing 34 buildings and obliterating 3,200 acres of chaparral habitat, the land is a lesson in allowing nature to take its course and the surprising life borne of a destructive conflagration.
“What’s really exciting is that we’re seeing regeneration of existing species that haven’t regerminated for 80 years,” said Carol Presley, an environmental engineer with the Santa Clara Valley Water District. “There are some plants we just haven’t seen for a long time.”
And most importantly, those plants are native species. What from a distance look like fields of common, invasive broom species from France and Scotland are actually yellow bush poppies, a chaparral plant. And the canyons are coated with baby knobcone pines standing just a foot or two off the ground.
Chaparral species are fire-adapted, meaning they actually need the destructive heat of a wildfire to fuel their life cycle. Without intense heat to melt the cones of the knobcone pine, they won’t regerminate. The canyons are now blanketed with fire-followers, plants that thrive with fire or take advantage of open space. District Botanist Janell Hillman said many of the species are uncommon and were unseen before the fire.
“It’s either because no one noticed them or the fire created a lack of competition that allowed the plants to get established,” Hillman said. “They aren’t good competitors and a fire opens up space for them.”
Among the unusual native species growing in the burn area are yerba santa, Hoffman’s sanicle, the Santa Cruz County monkey flower and Brewer’s calandrina, a fleshy plant with red flowers.
“When we found it growing on Croy, it was very vigorous, which is unusual,” Hillman said. “I think it’s very happy growing there in all the open space.”
Hillman’s favorite flowers that have risen from Croy’s ashes are the bush and fire poppies.
“When you have a chaparral environment, which is very dry and can seem very harsh, it’s very striking when you have flowers that are delicate and have large, showy petals.”
The last fire in the area was in 1923, and over 80 years the canyons flourished with tinder, overrun by aggressive invasive grasses and manzanita bushes stretching twenty feet to the sky.
The fire was overdue.
“The chaparral species depend on fire,” Presley said. “But areas that are populated don’t have fires because they’re suppressed. This is a natural event. The fire cleaned up the brush and reduced the fuel load, which is how things are supposed to naturally occur.”
And with natural events come unpleasant consequences. Croy and Eastman canyons are on the eastern slopes of the Santa Cruz Mountains, above Uvas Reservoir. Although the fire didn’t cause any direct damage to the county’s water ways, the water district became involved because the denuded hillside threatened the reservoir, a major water source in South County.
Without vegetation to hold soil in place, rainfall will cause runoff that carries silt into streams that feed the creek that ultimately supplies the reservoir. The silt collects in the reservoir and prevents water from filtering into the groundwater basin and reduces the reservoir’s capacity.
So in partnership with the Natural Resource Conservation Service, the California Department of Forestry and Fire Protection and a few local residents, the district helped secure the hillside and give nature a push in the right direction.
“We took a minimalist approach,” Presley said. “This is a natural event and we didn’t want to interfere with the process of regeneration. There are a lot of plants that will resprout on their own because they didn’t burn below the surface. You have to think about the ecology of what was there before you perform a mass treatment. Sometimes leaving a chaparral environment alone is the best thing to do.”
Native chaparral plants thrive on fire, but they need a year or more to flourish. To stabilize the canyon in the meantime, Presley said, the district sprayed hillside and roadways with sterile seed and mulch, a process known as hydraseeding that uses water and natural glue so seeds will stick to the steep hillsides. The grass sprouted immediately but didn’t reproduce or interfere with native regeneration.
Fire breaks were seeded and covered with straw. Homeowners were given native grasses to re-seed their yards.
Presley said that local residents were helpful in restoring the canyon and protecting the reservoir.
“They were instrumental in just helping us navigate, helping us just get around all that private land,” she said.
But some well-meaning homeowners were a little too helpful. One in particular rushed out and bought a lot of exotic grass seed. While native species are in abundance all over the canyon, they’ve yet to take over the spot where that resident seeded.
“A lot of times nurseries and people with good intention will suggest something like Italian rye because it grows so fast,” Presley said. In fact, what it does is prevent natives from growing.
Sandy Speegle’s house, spared in the fire, supplied water to firefighters and for the re-seeding project. She’s heartened by the way the canyon has rebounded, notwithstanding the proliferation of the hotdog-like foxtail.
“It looks really good,” Speegle said. “Everything grew back and everything grew back more. The only problem is that foxtail came back in force. The little stickers get into everything.”
Gilroy Dispatch reporter Matt King can be reached at mk***@gi************.com or 847-7240.
