Vegetation
Restoring the abundance of the endangered Sonoma spineflower

BY Michelle Coppoletta and Barbara Moritsch

michelle_coppoletta@nps.gov
Biological Science Technician, Point Reyes National Seashore, California

barbara_moritsch@nps.gov
Plant Ecologist, Point Reyes National Seashore, California

Perhaps restoring diversity is most of all about restoring hope.

Hope was restored in 2000 for the long-term protection of the federally listed, endangered Sonoma spineflower (Chorizanthe valida). The plant, which had last been recorded in 1903, was presumed to be extinct until botanist Wilma Follette discovered specimens in a grazed pasture on Point Reyes National Seashore, California, in 1980. Until now this population was the only known in the world. By combining efforts, however, the Point Reyes National Seashore Association and NPS vegetation managers established a second population on the seashore in 2000.

The original Sonoma spineflower population on the Point Reyes peninsula occurs on 2.5 acres (1 hectare) of coastal prairie. However, plant collections from the 1800s indicate that the flower formerly had a much broader range in Marin and Sonoma Counties. Intensive agriculture and urbanization since the early 1900s have significantly altered the habitat. Information from research suggests that today the species is limited by its dependence on grazing by cattle or wildlife, which reduces competition with nonnative plants, and its restriction to well-drained, disturbed, sandy soils. These ecological requirements, in addition to narrow endemism, render the plant particularly vulnerable to events such as disease outbreak, fire, flood, and other circumstances that could eliminate the population and cause extinction.

In 1999 the Point Reyes National Seashore Association provided the vegetation management program of the national seashore with funds for monitoring, evaluating, and expanding the existing population of the Sonoma spineflower and for developing management in accordance with the recovery plan of the U.S. Fish and Wildlife Service. According to the recovery plan, the species cannot be delisted until two additional populations are established and sustained.

By consulting historical records, soil maps, and local plant taxonomists, and by conducting field searches to identify potentially suitable habitat, the vegetation managers of the national seashore identified suitable sites for trial plantings with seeds from the existing population. Seeds were also placed in long-term storage in the seed bank facility of the Rancho Santa Ana Botanical Garden. A trial site was selected in similar habitat at another location on the national seashore, and in fall 1999, cattle troughs were removed, the soil was lightly disturbed with a rake, and 1,000 seeds were planted.

In 2000, seeds on the trial plot yielded 34 plants, all of which produced flowers and many of which later set seed. With additional funds from the association in 2000, the natural resource managers of the national seashore established two more plots within 565 feet (200 meters) of the first trial plot and planted them with seed from the first population.

Whether the new populations will persist over time cannot be predicted now. Nevertheless, the establishment of a second population is significant because it reduces the probability of extinction due to catastrophe and moves the Point Reyes National Seashore one step closer to the long-term conservation of the Sonoma spineflower.

[[Photo]]
Once believed to be extinct, the Sonoma spineflower occurs today only on the coastal prairie of Point Reyes National Seashore. In 2000, NPS resource managers and the Point Reyes National Seashore Association established a second population of the species from seed.

[[Photo]]
Natural resource managers and California Native Plant Society volunteers census the main population of the Sonoma spineflower each year. In the past the main population has exceeded 20,000 individuals, making the task of counting these small annuals a challenge.

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Last Updated: 06/17/2001
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