Human-caused wildfires in May burned more than a third of Santa Rosa Island, an offshore wildlife oasis in Southern California’s Channel Islands National Park, raising serious ecological concerns.
Concerns have become a stark reality on this windswept island, located in the ocean some 42 miles off the mainland and home to flora and fauna found nowhere else on Earth.
The fire, the largest in the park’s history, devastated Santa Rosa Island’s Torrey pine forest, one of the rarest pine trees in the world, according to a recent federal island damage assessment.
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Assessments showed that some trees died quickly, but the long-term outlook is even bleaker. Depending on the extent of the damage, 60% to 80% of the trees are expected to die, National Park Service spokeswoman Anna Cholo told CNN. Only 2% of the forest remains burnt, she added.
“Torrey pines are not well adapted to fire, so even minor burns can delay mortality,” Cholo said. “A detailed assessment is underway, but it could be at least a year before the full extent of the impact is known.”
This loss could have a trickle-down effect on the island. Perched on sandstone cliffs above the sea, these scaly, contorted pines catch mist with their needles, watering their roots and nearby plants and animals.
“Plants like this can impact local water availability and make a big difference in how much water is captured by organisms on the ground,” Heather Schneider, director of conservation research at the Santa Barbara Botanical Garden, told CNN.
Severe loss and budding grove
Even before the wildfires, Santa Rosa Island’s Torrey pine tree was “highly vulnerable to extinction” due to its limited range and gene pool, the National Park Service said.
Dustin Wolkis, director of science and conservation at the nonprofit Plant Conservation Center, told CNN that such small, isolated and rare plant communities are “extremely vulnerable” to destructive events such as fire.
“Any loss of genetic diversity could be catastrophic for humanity,” he says.
Genetic diversity increases the likelihood that some individuals will have the traits needed to withstand environmental changes, such as new diseases.
“Once genetic diversity is lost, it cannot be regained,” he says. “All you can do is maintain what you have.”
Genetics aside, the loss of a large portion of an already small population means fewer individuals will survive the next challenge.
“As the population declines, so does resilience,” Wolkis says.
Schneider said the island’s damaged forests could use some help from the mainland.
In what she called “an eerie twist of fate,” the botanical garden had been collecting seeds from the island’s pines for several years before the fire. She said the organization is able to grow seeds and recently established a seed reserve for them.
“So it’s a glimmer of hope that a subsample of island trees is safely in our gardens,” Schneider said, adding that there are about 40 more trees in the nursery.
She stressed that these plants could be deployed to help forests recover, but it will take time to determine whether intervention is needed.
Botanical gardens, plant conservation centers and other organizations are also dispersing more Santa Rosa Island Torrey Pine seeds, which Wolkis says is essential to protecting the rare plant community.
But the remaining island pines may have their own seed banks.
Schneider said trees shed most of their seeds as they grow, but some seeds persist for much longer, in some cases for more than 10 years. If some of those seeds remain in the treetops, even dead trees could help rebuild arboreal communities on the Santa Rosa Island bluffs.
Whether planted by hopeful humans or sprouting from scorched pine cones, the new island’s Torrey pines will be challenged to survive in an ecosystem shaped by global climate change.
Schneider said many plants require a relatively narrow range of environmental conditions to complete different stages of their life cycles, and conditions are changing in Santa Rosa. Temperatures are rising and the rainy season is starting later.
“It’s a difficult time to be a pine tree on Earth as the climate changes,” Schneider said. “The question I have is not only, ‘Are there still viable seeds in the cones that can fall and reproduce?'” But at the same time, “Will they experience the climatic conditions that will allow them to not only germinate, but mature and begin to reproduce?”
Before the fire, the grove was full of young trees, a sign to Schneider that conditions in the past few years were sufficient for seeds to germinate and grow. But young trees must survive for more than a decade before they can regenerate and sustain a forest, and the Earth’s climate continues to change.
If climate change makes the island hotter, drier and more prone to fires, the pine trees may be less likely to recover naturally, she said.
“Time will tell, but for now we feel hopeful about the possibility of reproducing it from seed.”
