Chorizanthe pungens var. pungens
|Listed||February 4, 1994|
|Description||Wiry, annual herb with white flowers growing in a dense cluster.|
|Habitat||Sandy soils within coastal dunes, scrub, grassland, maritime chaparral, and oak woodland communities.|
|Threats||Industrial and residential development, recreational use, and dune stabilization.|
The Monterey spineflower, Chorizanthe pungens var. pungens, has small white (rarely pink) flowers growing in a dense cluster. The inner and outer petal-like sepals (green covering of the flower) are equal in length and are lobed rather than fringed. The flower filaments are free, and there are three to nine stamens. There are six bracts below the flowers: three are toothed with the alternating three shorter. This wiry herb grows along the ground or slightly erect, which distinguishes it from the robust spineflower, which is an endangered species. Monterey spineflower flowers are produced from April through June and the seed is collectable through August.
Seed dispersal is facilitated by the involucral spines, which attach the seed to passing animals. The preference of these species for gaps in the vegetation or sparsely vegetated areas on sandy substrate allows seedlings to establish in areas that are relatively free from other competing native species; this is particularly true for Monterey spineflower which prefers bare soils. State park personnel hypothesize that trampling along trails may actually aid germination or seedling establishment, by suppressing competition, which could be offset by trampling mortality to the plants.
C. pungens var. pungens is classified as a separate variety from var. hartwegiana (Ben Lomond spine-flower) of the Santa Cruz Mountains.
The robust spineflower is endemic to sandy soils of coastal habitats. The plant is found within coastal dunes, scrub, grassland, maritime chaparral, and oak woodland communities along and adjacent to the coast of southern Santa Cruz and northern Monterey counties, and inland to the coastal plain of Salinas Valley. Broad, sandy beaches backed by an extensive dune formation characterize the inner rim of Monterey Bay. Just inland from the immediate coast, maritime chaparral occupies areas with well-drained soils. Coastal dunes and coastal scrub communities exist along the inner rim of Monterey Bay.
This plant occurs in areas of relatively mild maritime climate, characterized by fog and winter rains. The fog helps keep summer temperatures cool and winter temperatures relatively warm, and provides moisture in addition to the normal winter rains.
Recent surveys at Fort Ord indicated that within grassland communities the plant occurs along roadsides, in firebreaks, and in other disturbed sites. In oakland woodland, chaparral, and scrub communities, the plants occur in sandy openings between shrubs. In older stands with a high cover of shrubs, the plant is restricted to roadsides and firebreaks. The highest densities are located in the firing range, where disturbance is most frequent. There seems to be a correlation between open conditions resulting from activities that disturb habitat.
C. pungens var. pungens is known from seven occurrences with as many as 1.2 million individuals, the apparent majority of them at Fort Ord. It occurs from the Monterey peninsula northward along the coast to southern Santa Cruz County, and inland to the Salinas Valley. Early collections from 1842 indicated that this species historically occurred as far south as San Simeon near the northern boundary of San Luis Obispo County, but in recent times this species has not been found south of the Monterey Peninsula. In the Salinas Valley, Monterey spineflower is now limited to a few occurrences near Prunedale. The northernmost occurrence occurs in Day Valley near Soquel in Santa Cruz County.
Surveys have been conducted at Fort Ord in recent years in preparation for closing the base. In 1992, it was found in almost all the undeveloped areas on the western half of Fort Ord. More recently The U.S. Bureau of Land Management (BLM) conducted comprehensive surveys and determined that the previous study's interpretation of data had grossly overestimated occupied habitat at 70%. The new study estimated occupied habitat at 1-10%. The original survey used large blocks of habitat and the calculations included closed canopy blocks of woody vegetation. The reduction in estimated occupied habitat implies a population between 200,000 and two million individuals. These numbers require further refinement to understand status and trends for occurrences on Fort Ord.
Plans call for approximately 60% of the habitat to remain in open space, protecting as many as 1.2 million to as few as 120,000 plants. The 8,000-acre (3,200-hectare) impact area of unexploded ordinance has not been surveyed. Additionally, BLM is concerned that the beach habitats have not been thoroughly inventoried and suggests that there is as much as 2,500 acres (1,000 hectares) of potential habitat on the stretch of beach from Manresa State Beach to Pacific Grove, which includes private lands. The BLM estimated that there are only 108 acres (43.2 hectares) of potential habitat. The farthest inland population currently known is at Manzanita Park near Prunedale (Monterey County), where C. pungens was mapped in 1989. This is the farthest inland occurrence currently known to exist. Populations are found on state park system lands at Manresa, Marina, Sunset, Salinas River, and Asilomar State Beaches and Fort Ord Dunes State Park.
In 1987, a survey of six properties in the Marina Dunes found a total of 43 individuals of Monterey spineflower on five of the properties: Marina State Beach, Granite Rock Company, Gullwing, RMC Lonestar Cement Company, and Martin. The occurrence at this site might be more extensive than indicated as the survey was conducted in a poor rainfall year. Other occurrences are known from Pebble Beach.
Habitat loss and conversion for agricultural and residential development, activities at military institutions, and invasion by non-native plants were identified as the primary threats to Monterey spine-flower. Hikers and equestrians may trample this plant at locations throughout its range. Residential and golf course development in maritime chaparral habitat is a potential threat to several occurrences in Monterey and Santa Cruz counties. The proposed route realignment of Highway 101 in northern Monterey County also has the potential to affect several small, scattered occurrences.
Most of the historical locations of Monterey spineflower in the Salinas Valley have probably been extirpated by conversion of grassland and valley oak woodland habitats to agricultural fields. The one remaining occurrence near Prunedale is in Manzanita County Park, but the park has no management plan for this species and this species is threatened in the park by plans to replace the natural vegetation with turf for playing fields. Construction of roads and buildings on Fort Ord possibly destroyed some occurrences of this species in the past. Conversion of this military base to other uses, including educational and scientific research facilities, may threaten this species if new buildings are constructed; however, large portions of this plant's habitat on Fort Ord are to be reserved for open space.
When Monterey spineflower was listed in 1992, its occurrences at Sunset State Beach were threatened by recreational activities, with plants subject to trampling and invasive non-native species introduced as part of dune stabilization programs. The invasive iceplant is now a dominant species of stable and moderately active dunes in Monterey Bay. Iceplant forms dense, continuous mats of succulent vegetation with few or no gaps, in contrast with the sparse cover of native vegetation. Cover by iceplant of dunes near Fort Ord can exceed 80%, even in areas that were subject to mass dieback during the freezes of the early 1990s. Because of the persistent re-invasion of stable dunes by iceplant, and the progressive increase of iceplant colonies over time, invasion by this species appears to be the greatest long-term threat to the survival of Monterey spineflower. Limited corrective measures have been taken against iceplant invasion, but recurrent invasion by iceplant will continue to be problematic unless iceplant eradication is undertaken on a massive scale, so as to destroy the seed sources.
Conservation and Recovery
Restoration of dunes at the Naval Postgraduate School in Monterey where Monterey spineflower occurs may benefit this species. This restoration work has included removing non-native invasive species such as iceplant, converting previous landfills and other semidune areas to natural coastal dunes and coastal prairies, and planting native species. The total area restored is about 30 acres (12 hectares). The Monterey spineflower occurrence at Sunset State Beach may be enhanced by a restoration program established for the removal of non-native species. At sites like these, budgeting for long-term maintenance is essential to the success of iceplant removal because it rapidly re-invades cleared plots, often reestablishing dominance within several years. Monitoring of these sites is necessary to determine if the conservation efforts are successful.
The County of Santa Cruz allows only resource-dependent uses within environmentally sensitive habitat areas, including habitat for rare and endangered species. For proposed land divisions or developments, the County requires protection of environmentally sensitive habitats through dedication of an open space or conservation easement to protect the portion of a sensitive habitat that is undisturbed by the proposed development. Alternatively, the developer may protect sensitive habitat on an adjacent parcel.
The U.S. Department of Defense (DOD) developed the Fort Ord Habitat Management Plan that documented the occurrences within the military facility as part of the base closure plans. The plan delineates the habitats on the site that will be set aside for preservation and which occurrences may be affected by future development. Designating large portions of Fort Ord as open space will provide conservation opportunities for this species providing protection for 55% of the known habitat on the former base. When Fort Ord was still operating as a military facility, the DOD established small preserves, from 4-42 acres (1.6-16.8 hectares), to protect rare species. Under the Habitat Management Plan, BLM will be responsible for portions of the sensitive habitat areas, as will the University of California. More than 16,000 acres (6,400 hectares) of Fort Ord are slated for preservation as open space and native plant and wildlife habitat. The university as part of its natural reserve system will manage portions of the Monterey spineflower occurrences.
U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
U.S. Fish and Wildlife Service
2493 Portola Road, Suite B
Ventura, California 93003-7726
Telephone: (805) 644-1766
U.S. Fish and Wildlife Service. 4 February 1994. "Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for Three Plants and Threatened Status for One Plant from Sandy and Sedimentary Soils of Central Coastal California." Federal Register 59 (24): 5499-5511.