Botanist Fears Rare Plant Deaths in Torrey Pines Brush Fire

Jon Rebman is almost too scared to learn to what extent a brush fire wiped out rare and native plants when Torrey Pines State Natural Reserve Extension caught fire last week. 

The botany curator at San Diego Natural History Museum spent his 32-year career scrounging for and studying the reserve extension, one of San Diego’s most biodiverse habitats. He’s never seen it catch fire. And he’s not sure whether hundreds of plant species can survive being scorched and compete with an onslaught of weeds that clamber in to take their place.  

“Once you disturb this area, all of these weed seeds come in. They’re good at pioneering and can establish themselves quickly. That worries me,” Rebman said.  

The blaze sparked in the afternoon of June 25 and encumbered more than 19 acres as onshore winds pushed smoke toward the Del Mar Heights neighborhood, forcing 2,500 people to temporarily evacuate. Two firefighters suffered heat exhaustion while battling the flames, the Union-Tribune reported. The cause is still unknown. 

As of Wednesday afternoon, firefighters estimated the fire had torn through a large patch of wildland between Red Ridge Trail and Mar Scenic Drive, according to a rendering from San Diego Fire Department spokesperson Monica Muñoz. The fire department doesn’t take stock of lost trees or plants. That’s California State Parks’ job, she said. 

It’s a big job. The confluence of an elevated coastal cliff soils, cooled ocean air and the dewy marine layer create a microhabitat of pine woodland that’s exceedingly rare in developed Southern California. The 2,000-acre coastal wilderness supports more than 700 recorded plant species and counting. Rebman and his team found 85 new plants in 2023 alone that hadn’t yet been recorded at the reserve’s extension – a less-traveled area south of the popular hiking trails of the main reserve next to Los Peñasquitos Lagoon. The fire may have wiped out undiscovered ones before researchers could document them. 

“It’s such a rare habitat,” Rebman said. “We just hope it didn’t kill the trees or a lot of the other really rare plants there.” 

There’s a chance the fire destroyed some of the endangered and namesake Torrey Pines that thrive here. The species is one of the rarest trees in the world and can only be found in the reserve and on Santa Rosa Island in the Channel Islands.  

“You can imagine for those plants and animals that live in this same microhabitat, that’s all they have left,” Rebman said.  

That means its hard times ahead for California wedge grass, an extremely rare annual grass thought to be lost or extinct until Rebman’s team rediscovered it growing along the reserve’s sandy trails.  

The Del Mar Manzanita is another at-risk native. This fruiting, festive little bush homesteads in the sandstone outcroppings of coastal bluffs. Coyotes dine on its red berries. But the plant is so rare, found only in San Diego and Riverside counties, that it’s protected by the federal Endangered Species Act. 

The extreme plant biodiversity in Torrey Pines Reserve reflects how San Diego looked pre-colonial contact. And rare and endangered things that could be lost due to fire, growing more frequent with human-caused climate change, remind us what else we stand to lose in the country’s most biodiverse county.  

“We’re constantly losing biodiversity throughout our county,” Rebman said.