San Jacinto Valley Crownscale

Atriplex coronata var. notatior

Description

San Jacinto Valley crownscale, Atriplex coronata var. notatior, a member of the goosefoot family (Chenopodiaceae), is an erect, gray-scurfy annual, 4-12 in (10.2-30.5 cm) tall. The grayish leaves are sessile, alternate, 0.3-0.8 in (0.8-2 cm) long and elliptic to ovate-triangular in outline. Male and female flowers occur on the same plant. The female flowers are obscure and develop spherical bracts with dense tubercles in the fruiting phase. San Jacinto Valley crownscale germinates after the water has receded. It usually flowers in April and May and sets fruit by May or June.

San Jacinto Valley crownscale can be distinguished from the more northern A. coronata var. coronata by its erect stature, the spheric shape of the bracts together in fruiting stage, and the more numerous tubercles and marginal teeth on the bracts. San Jacinto Valley crownscale occurs with eight other native and one introduced species of Atriplex within its range. It can be distinguished from these species by a combination of characteristics, including annual habit, the shape of the leaf, and the size and form of the bract.

Habitat

San Jacinto Valley crownscale is restricted to highly alkaline, silty-clay soils. Most populations are associated with the Willows soil series. It occurs in alkali sink scrub, alkali playa, vernal pools, and, to a lesser extent, in annual alkali grassland communities. These areas are typically flooded by winter rains. The duration and extent of flooding are extremely variable from one year to the next.

Distribution

San Jacinto Valley crownscale is restricted to the San Jacinto, Perris, Menifee and Elsinore Valleys of western Riverside County, California. This taxon consists of 11 population centers that are primarily associated with the San Jacinto River and Old Salt Creek tributary drainages. One additional isolated and small population has recently been discovered in Willows soils near Lake Elsinore.

The number of individuals of San Jacinto Valley crownscale in a population complex varies in any given year in response to rainfall, extent of winter flooding, and temperature. Disturbance (discing, dryland farming, pipeline construction, out of season inundation) has become an increasingly important factor in limiting the number of individuals in a population.

Between 1990 and 1994, an estimated 78,000 San Jacinto Valley crownscale individuals were located. These plants occupied about 400 acres (162 hectares) of about 8,200 acres (3,318.5 hectares) of potentially suitable habitat (alkali scrub, alkali playa, and annual alkali grassland vegetation associations). The majority of the individuals (about 75%) were associated with three population centers (Mystic Lake, the Nuevo-Ramona Expressway segment of the San Jacinto River, and west Hemet). Since 1993, the population has apparently declined significantly as a result of major flooding in the winter of 1992-93 and the subsequent conversion or alteration of potential habitat. Several new populations have since been discovered near historic populations, including 5,200 individuals on the San Jacinto River and fewer than 200 individuals near Elsinore, California. However, new discoveries have not appreciably balanced the reduction of populations.

The majority of the population centers of San Jacinto Valley crownscale are located on privately owned lands. Three populations are on state land (San Jacinto Wildlife Area), one population is partially on the Riverside County Habitat Conservation Agency along the San Jacinto River, and one population is on a private preserve managed. This plant is not known to occur on Federal lands.

Threats

About 95% of the populations of San Jacinto Valley crownscale, about 15% of the populations of thread-leaved brodiaea, and about 50% of the populations of spreading navarretia (Navarretia fossalis ) are associated with the San Jacinto River and a tributary of Old Salt Creek just west of the city of Hemet. Much of this area has been subject to dry land farming or irrigated farming at some time during the last 100 years. However, a five year drought contributed significantly to a reduction in agricultural activity, particularly along the San Jacinto River. Conversely, in some areas, the soils have routinely been too wet and too alkaline for dry land farming. Both factors have contributed to the continued existence of these taxa in this area.

Major commercial and urban development, transportation, and flood control projects have been proposed in General and Specific Plans for both the San Jacinto River Valley and the area west of Hemet. According to documents on file with the County of Riverside and the City of Perris in 1994, these proposals could result in more than 19,000 new residential units, as well as hotel and commercial developments. Potential habitat for San Jacinto Valley crownscale, spreading navarretia, and thread-leaved brodiaea could be reduced by over 3,500 acres (1,416.5 hectares). Although the urbanization that could result from these major projects and others associated with the cities of San Jacinto and Hemet may not occur for up to five years, these same areas are more imminently threatened by a recent increase in pipeline construction, dry land farming, and weed abatement activities.

The Mystic Lake bed and surrounding shoreline areas potentially support more than 1,000 acres (404.7 hectares) of suitable habitat for San Jacinto Valley crownscale. In fact, the largest known population was reported in this area in 1992. However, prior to 1992, a significant portion of the lake bottom was under cultivation. In 1993, major flooding filled the lake and this population and several others were inundated. The lake did not recede enough to expose the former population until 1996. Few plants have been reported where 20,000 individuals once occurred. Most of the Mystic Lake area is not within the San Jacinto Wildlife Area and has no formal protection. It has been proposed that reclaimed water be piped into Mystic Lake. The addition of water outside the normal rainy season will undoubtedly slow recovery of suitable habitat for San Jacinto Valley crownscale in this area.

While San Jacinto Valley crownscale has displayed some ability to persist despite dryland farming in its habitat, its severe decline since 1992, combined with extensive plans for flood control and further urban development in its habitat show that this plant is in danger of extinction in much of its remaining habitat. The existing protected areas do not appear to offer adequate area or management to prevent endangerment. Nearly half of the known populations of spreading navarretia occur within the same habitat that is occupied by San Jacinto Valley crownscale. However, the distribution of spreading navarretia is even more restricted in that it can only persist in the wettest areas of the San Jacinto River flood plain and the vernal pools at Hemet. The loss of these populations will result in a significant decline in the species.

Conservation and Recovery

A permit was issued by the U.S. Army Corps of Engineers for channelizing the San Jacinto River in 1996. As a condition of approval, the permit was tied to a plan that would be designed to conserve San Jacinto Valley crownscale habitat along a portion of the San Jacinto River. It is anticipated that this conservation plan will provide adequate habitat for rare plant species, including spreading navarretia. It will cover about one-third of the range of San Jacinto Valley crownscale. This conservation plan is intended to adequately conserve San Jacinto Valley crownscale (but not spreading navarretia) in the covered area and to allow for its full recovery once similar conservation measures are undertaken elsewhere in its range.

Contact

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232
http://pacific.fws.gov/

Reference

U. S. Fish and Wildlife Service. 13 October 1998. "Determination of Endangered or Threatened Status for Four Southwestern California Plants from Vernal Wetlands and Clay Soils." Federal Register 63 (197): 54975-54994.