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A race against time: saving seeds to protect threatened plants in California

Binational conservation efforts offer hope for the protection of plant species living on both sides of the U.S.-Mexico border.

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Abies bracteata, or bristlecone fir, is one of the rarest North American species of Abies. This once more widespread conifer is now restricted to five extremely remote locations on the western slopes of the Santa Lucia Mountains of the central California coast. For Evan Meyer, now executive director at the Theodore Payne Foundation, collecting seeds of bristlecone fir back in 2017 began as a personal challenge.

“There were generations and generations of botanists and horticulturalists who had been fascinated by this tree and tried to get [seeds] and failed so many times,” he says.

There are numerous reasons for why the seeds of these spindly trees have only been collected a handful of times. Bristlecone fir is a masting species, meaning that it produces heavy seed crop in certain years (the mast years), but few or none in others. Besides, the fragile cones are hard to reach. 

And these are not the only challenges when collecting rare and threatened plants, like bristlecone fir. These plants usually occur in small populations or in disturbed places that are difficult to access, and plants might have low seed set or be consumed by predators.

“It takes a lot of upfront work to do the scouting, to make sure that the population is healthy enough that you can collect seed without impacting the population in any given year,” says Naomi Fraga, director of conservation programs at the California Botanic Garden (formerly Rancho Santa Ana Botanic Garden). “We already have the challenges stacked against us in every year of field work.”

Emergence of a seedling of Astragalus magdalenae var. peirsonii or Peirson’s milkvetch, a rare species that occurs on the Algodone Dunes in Imperial County. Photograph credit: Duncan Bell, Senior Field Botanist. Courtesy of Naomi Fraga.

For Meyer, third time was a charm. In 2017, having already attempted to gather the coveted seeds twice, Meyer asked an arborist friend to climb to the top of the tree. Their operation did not disappoint:  The germplasm Meyer and his friend collected is now stored in a freezer at the California Botanic Garden in Claremont, California — and not as a personal trophy. The seeds might prove invaluable for present and future conservation strategies. Climate change and drought are the main threats for the future of this narrow endemic, but the stock that Meyer managed to collect offers hope.

Seeds of Abies bracteata are not sitting alone in that freezer. The California Botanic Garden holds seeds of rare and threatened taxa from across the state and this is not the only institution acting as ‘Noah’s Ark.’ Seeds of plants without legal protection occurring in California are being collected and tucked in freezers around 11 facilities as part of the California Plant Rescue Initiative (CaPR). The collaboration started in 2015 to safeguard these plants and to learn about their germination and seedling morphology.

California Seed Bank. The seed bank facility at California Botanic Garden, home to a substantial and diverse collection of California native plants. Courtesy of California Botanic Garden.

Back in 2014, Meyer and Fraga found that 59% of California rare plant taxa legally protected by federal or state laws were well represented in ex situ collections. On the other hand, 17% of rare plants without the same protections were not kept in any collections outside of their natural habitat.

“[W]e knew that we had to make things happen in some other way in order to get those plants the attention they deserve to make those collections,” Fraga recalls.

After having identified this legal loophole and realizing that some institutions were already seed banking, Meyer, Fraga and their colleagues decided to join efforts in a race against time.

“There’s direct anthropogenic threats, and those are increasing, and now we have the threat of climate change to contend with,” she says.

Christa Horn, coordinator of CaPR, recently shared the results of their efforts at the State of Biodiversity Symposium organized by the San Diego Natural History Museum. Horn mentioned that by the end of 2020, CaPR partners had collected 64% of the 1,166 rare and threatened species whose populations have declined significantly over the last century. She also said that the northeastern part of the state is poorly represented in the collections.

And CaPR is not only after seeds. Every time someone like Meyer or Fraga takes to the field, they also keep record of the state of the populations from where they gather seeds, many of which have not been seen for over forty years.

“We [at CaPR] are not thinking of ourselves as seed savers to create future populations,” says Fraga. “I think the important focus is that the work that we do should be in tandem with support of habitats and ecosystems.”

Following guidelines from the Center for Plant Conservation, collectors take 10% of the plant so that wild populations remain viable. They also take seeds from individual plants, also known as maternal line collections, to increase genetic diversity representation.

Castilleja mollis – Santa Barbara Botanic Garden maintains several small seed collections of Castilleja mollis in an effort to represent the diversity of this species. Photograph by Christina Pang, SBBG. Courtesy of Christa Horn.

And California is not the only region holding this trove of plant diversity. The California Floristic Province is a global biodiversity hotspot due to its high rates of endemism and levels of threat to native taxa. The region, extending from Santa Barbara, California into northern Baja California in Mexico, is characterized by a Mediterranean-type climate with hot, dry summers and cool, wet winters.

Since plants know nothing about imaginary lines, CaPR has recently expanded its geographic scope to include species in Mexico. Since 2018, ecologist Sula Vanderplank from the San Diego Natural History Museum and technician Carlos González have been looking for populations of plants considered endangered and threatened, both in the U.S. and Mexico, in the northern state of Baja California.

“When we think about plant conservation in California, it is crucial to consider their populations in Baja California,” she says.

At this stage, the aim of CaPR in Mexico is not so much banking seeds, as relocating populations of rare plants using old herbarium specimens or observations made by local hikers who upload their photographs to Naturalista, a Mexican social network where people share their observations online. From their scouting, they have even described new species.

“Most of the new populations we are finding is thanks to the observations people have recorded on Naturalista,” Vanderplank says.

Once found, Vanderplank and González record the status of the population and identify threats. The main goal is to create a database of the rare and threatened plants of Baja California since so little is now known. When they do get a chance to gather seeds, they ship them to the Faculty of Higher Studies (FES) Iztacala in the State of Mexico, home to the country’s main seed bank.

Vanderplank regrets the disappearance of the vernal pool ecosystems in California and sees the great potential for doing conservation in Baja California, where vernal pools are still part of the landscape.

“There are plenty of opportunities to protect and conserve within Baja California that are nonexistent in California. If we can think more binationally, we can do a lot more for the conservation of these rare species,” she says.

Fraga, in California, agrees that seed banking should not be the main strategy for conservation. “There’s really no replacing protecting the wild source population from which we collected. The act of the collection should enhance overall conservation of the species in its natural habitat.”

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