Nevin's Barberry

Berberis nevinii

Description

Berberis nevinii (Nevin's barberry), a member of the barberry family (Berberidaceae), was described by Asa Gray (1895) based on a collection made by Joseph Nevin in 1892 on the east side of the San Fernando Valley near Los Angeles. Berberis nevinii has been treated as Mahonia nevinii and Odostemon nevinii. Recent authorities follow Gray's treatment.

Berberis nevinii is a rhizomatous evergreen shrub 3-12 ft (1-4 m) tall. The pinnately compound leaves (featherlike arrangement of the leaflets) are gray-green with serrate, spine-tipped margins. The flowers, clustered in loose racemes, have six yellow petals arranged in two series. The berries are juicy, yellowish to red, less than 0.3 in (6-8 mm) long with brownish seeds. This species flowers from March through April. Berberis nevinii is distinguished from other members of the genus by its nearly flat, narrow, serrate, pinnately veined leaves, few flowered racemes, and reddish fruits.

Habitat

The Nevin's barberry occurs in restricted and localized populations from the interior foothills of San Diego County and northwestern Baja California, Mexico. It occurs in chaparral and alluvial scrub associated with rocky slopes and sediments and sandy washes. It is found in two habitat types: gravelly wash margins in alluvial scrub, and on coarse soils in chaparral, typically between 900 and 2,000 ft (275-610 m) in elevation.

Chaparral habitats of the interior foothill region of southern California are dense shrub associations of moderate height dominated by chamise, California lilac, red berry, manzanita, California scrub oak, sugar bush, laurel sumac, toyon, California buckwheat, and black sage. Chaparral plant communities are adapted to nutrient poor soils, cool wet winters, and hot dry summers.

Distribution

One of the two largest known populations of B. nevinii occurs near Vail Lake in southwestern Riverside County. The other large population of B. nevinii is in San Francisquito Canyon on the Angeles National Forest in Los Angeles County. The majority of B. nevinii plants found outside the Vail Lake and Angeles National Forest sites occur as isolated populations in San Bernardino and Los Angeles Counties.

Historically, the range of this species probably consisted of fewer than 30 scattered occurrences. At least seven populations have been extirpated, probably due to factors associated with urbanization. The species' native range currently extends from the foothills of the San Gabriel Mountains of Los Angeles County to near the foothills of the Peninsular Ranges of southwestern Riverside County. The total number of individuals is reportedly fewer than 1,000, but may be fewer than 500. The largest remaining cluster of native populations, which collectively contain about 200 individuals, occurs in Riverside County in the Vail Lake/Oak Mountain area. Most of these populations are on private lands in the Vail Lake region, although a few individuals occur on Bureau of Land Management lands north of Vail Lake and in the Cleveland National Forest southeast of Vail Lake. In Los Angeles County, another population of 130-250 individuals occurs on an alluvial terrace and on steep slopes in San Francisquito Canyon, Angeles National Forest. Another site was recently discovered on the Angeles National Forest. Two other native populations are small, with fewer than 10 individuals, and occur on private lands.

The range of Berberis nevinii has been extensively surveyed, and additional populations are not likely to occur in the Vail Lake area. Searches for B. nevinii, based on Boyd's habitat parameters, revealed no additional plants in the San Bernardino National Forest.

Threats

This species is imperiled by various activities, including urbanization and off-road vehicle use, that result in habitat modification, destruction, degradation, and fragmentation. The specific soil and/or hydrological requirements of this plant species naturally limit their distribution to clay soils formed from gabbro and alluvial or sedimentary based substrates (sandy washes and terraces) within the chap-arral or scrub plant communities. Most of the allu-vial scrub habitat in the San Fernando and San Gabriel valleys has been eliminated by urban development, road widening, flood control measures, or habitat degradation from extensive recreational use. Urban development and mining have generally impacted these habitat types more directly than other activities within the chaparral community, the terrain being more accessible than the typically rugged, steep, boulder-covered terrain of the surrounding chaparral.

Populations of Berberis nevinii occurring in allu-vial scrub habitats of Los Angeles County have been heavily impacted. A note on a specimen of B. nevinii collected in 1932 stated that there were only about 100 plants known, all east of San Fernando Road, and that their numbers were likely to decrease. Urbanization and brush fires are causes of the hastened rate of extinction of this species in the area near San Fernando (Los Angeles County). Several sites apparently containing B. nevinii in this area have been destroyed by the extensive urbanization of the eastern San Fernando Valley. A new occur-rence of a single plant was found in 1998 in a canyon on the south slope of the San Gabriel Mountains. The occurrence, of questionable origin because it was near an old nursery, consisted of a single plant on a parcel with an approved tentative tract map; this site was recently cleared.

The majority of the 16 native occurrences for Berberis nevinii, which are all located in the vicinity of Vail Lake in western Riverside County, consist of five or fewer plants. Urban development in the Vail Lake area threatens the largest group of occurrences of B. nevinii, and most of these occurrences at Vail Lake would likely be eliminated by development. Parcels recently sold at Vail Lake contain about 15 of the 16 occurrences and apparently contain more than 150 of the approximately 200 plants of B. nevinii in western Riverside County. An application for a conditional-use permit has been filed for one of the parcels that has both B. nevinii and another federally listed plant species, Dodecahema leptoceras (slender-horned spineflower). This parcel is also adjacent to a parcel that supports Ceanothus ophiochilus.

Conservation and Recovery

The California Fish and Game Commission listed Berberis nevinii as endangered. Although state law prohibits taking state-listed plants, these statutes inadequately protect against the taking of such plants through habitat modification or land use change by the landowner.

The U.S. Fish and Wildlife Service is working with Riverside and San Bernardino Counties to create multispecies habitat conservation plans that may benefit Berberis nevinii. San Bernardino County and Riverside County have signed planning agreements with local, state and federal agencies including the Fish and Wildlife Service.

Contact

Loren Hays, Chief Branch of Listing and Recovery
U.S. Fish and Wildlife Service
Carlsbad Field Office
2730 Loker Avenue West
Carlsbad, California 92008-6603
Telephone: (760) 431-9440
Fax: (760) 431-9624

Reference

U.S. Fish and Wildlife Service. October 13, 1998. "Endangered or Threatened Status for Three Plants from the Chaparral and Scrub of Southwestern California." Federal Register 63(197): 54956-54971.