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Proposed Rule

Endangered and Threatened Wildlife and Plants; Reopening of Public Comment Period and Notice of Availability of Draft Economic Analysis for Proposed Critical Habitat Determination for the Chorizanthe robusta

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Fish and Wildlife Service, Interior.


Proposed rule; reopening of public comment period and notice of availability of draft economic analysis.


We, the U.S. Fish and Wildlife Service (Service) announce the availability of a draft economic analysis for the proposed designation of critical habitat for the robust spineflower (Chorizanthe robusta var. robusta). We are also providing notice of the reopening of the public comment period for the proposal to designate critical Start Printed Page 48226habitat for this plant to allow all interested parties to comment simultaneously on the proposed rule and the associated draft economic analysis. Comments previously submitted need not be resubmitted as they already have been incorporated into the public record and will be fully considered in the final rule. Comments submitted during this comment period will also be incorporated into the public record and will be fully considered in the final rule.


The comment period is opened and we will accept comments until October 19, 2001. Comments must be received by 5:00 p.m. on the closing date. Any comments that are received after the closing date may not be considered in the final decision on this proposal.


Copies of the draft economic analysis are available on the Internet at “ or by writing to the Field Supervisor, U.S. Fish and Wildlife Service, Ventura Fish and Wildlife Office, 2493 Portola Road, Suite B, Ventura, California 93003.

All written comments should be sent to the Field Supervisor at the above address. You may also send comments by electronic mail (e-mail) to “”. Please submit electronic comments in ASCII file format and avoid the use of special characters and encryption. Please include “Attn: RIN 1018-AH83” and your name and return address in your e-mail message. If you do not receive a confirmation from the system that we have received your e-mail message, contact us directly by calling our Ventura Fish and Wildlife Office at phone number 805-644-1766. Comments and materials received will be available for public inspection, by appointment, during normal business hours at the above Service address.

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Catrina Martin, Assistant Field Supervisor, Ventura Fish and Wildlife Office, at the above address (telephone 805-644-1766; facsimile 805-644-3958).

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Chorizanthe robusta var. robusta, also known as robust spineflower and Aptos spineflower, is endemic to sandy soils in coastal areas in southern Santa Cruz and northern Monterey counties. In California, the spineflower genus (Chorizanthe) in the buckwheat family (Polygonaceae) comprises species of wiry annual herbs that inhabit dry sandy soils, both along the coast and inland. Because of the patchy and limited distribution of such soils, many species of Chorizanthe tend to be highly localized in their distributions.

Like other spineflowers, Chorizanthe robusta var. robusta is branched from the base and subtended by a rosette of basal leaves. The overall appearance of C. r. var. robusta is that of a low-growing herb that is soft-hairy and grayish or reddish in color. The plant has an erect to spreading or prostrate habit, with large individuals reaching 50 centimeters (cm) (20 inches (in.)) or more in diameter. This taxon is distinguished by white (rarely pinkish) scarious (translucent) margins on the lobes of the involucre (circle or collection of modified leaves surrounding a flower cluster) or head that subtend the white-to rose-colored flowers. The aggregate of flowers (heads) tend to be 1.5 to 2.0 cm (0.6 to 0.8 in.) across in diameter and distinctly aggregate. Chorizanthe robusta var. robusta is one of two varieties of the species Chorizanthe robusta. The other variety (Chorizanthe robusta var. hartwegii), known as Scotts Valley spineflower, is restricted to the Scotts Valley area in the Santa Cruz Mountains.

Chorizanthe robusta var. robusta is a short-lived annual species. It germinates during the winter months and flowers from April through June; although pollination ecology has not been studied for this taxon, pollinators observed include leaf cutter bees (megachilids), at least 6 species of butterflies, flies, and sphecid wasps (Randy Morgan, biologist, Soquel, California, pers. comm. 2000). Each flower produces one seed; depending on the vigor of the individual plant, dozens, if not hundred of seeds could be produced. The importance of pollinator activity in seed set has been demonstrated by the production of seed with low viability where pollinator access was limited (Harding Lawson Associates 2000). Seed is collectable through August. The plants turn a rusty hue as they dry through the summer months, eventually shattering during the fall. Seed dispersal is facilitated by the involucral spines, which attach the seed to passing animals. While animal vectors most likely facilitate dispersal between colonies and populations, the prevailing coastal winds undoubtedly play a part in scattering seed within colonies and populations.

The locations where Chorizanthe robusta var. robusta occurs are subject to a mild maritime climate, where fog helps keep summer temperatures cool and winter temperatures relatively warm, and provides moisture in addition to the normal winter rains. Chorizanthe robusta var. robusta is currently known from a total of seven sites. Two sites are located on active coastal dunes, while the other five sites are located inland from the immediate coast in sandy openings within scrub, maritime chaparral, or oak woodland habitats. All of these habitat types include microhabitat characteristics that are suitable for C. r. var. robusta. First, all sites are on sandy soils; whether the origin of the soils are from active dunes or interior fossil dunes is apparently unimportant. Second, these sites are relatively open and free of other vegetation; sandy soils tend to be nutrient-poor, which limits the abundance of other herbaceous species that can grow on them. However, if these soils have been enriched, either through the accumulation of organic matter or importation of other soils, these sandy soils may support more abundant herbaceous vegetation which may then compete with C. r. var. robusta. Management of the herb cover, either through grazing, mowing or fire, may allow the spineflower to persist. In scrub and chaparral communities, C. r. var. robusta does not occur under dense stands, but will occur between more widely spaced shrubs.

The current distribution of Chorizanthe robusta var. robusta is restricted to coastal and near-coastal sites in southern Santa Cruz County and northern Monterey County, ranging from Pogonip Park in the city of Santa Cruz, southeast to coastal dunes between Marina and Seaside that were formerly part of Fort Ord. With the discovery of two new populations in the year 2000, a total of seven populations are now known to exist. There is a high likelihood that other populations will be discovered in the future.

Portions of the coastal dune, coastal scrub, grassland, chaparral, and oak woodland communities that support Chorizanthe robusta var. robusta have been eliminated or altered by recreational use, conversion to agriculture, and urban development. Dune communities have also been altered in composition by the introduction of non-native species, especially Carpobrotus spp. (sea-fig or iceplant) and Ammophila arenaria (European beachgrass), in an attempt to stabilize shifting sands. In the last decade, significant efforts have been made to restore native dune communities, including the elimination of these non-native species.

Pursuant to the Endangered Species Act of 1973, as amended (Act), Chorizanthe robusta var. robusta was listed as endangered on February 4, 1994 (59 FR 5499). On February 15, Start Printed Page 482272001, we published in the Federal Register (66 FR 10419) a rule proposing critical habitat for the Chorizanthe robusta var. robusta. Approximately 660 hectares (1,635 acres) of land fall within the boundaries of the proposed critical habitat designation. Proposed critical habitat is located in Santa Cruz County, California, as described in the proposed rule.

Section 4(b)(2) of the Act requires that the Secretary shall designate or revise critical habitat based upon the best scientific and commercial data available and after taking into consideration the economic impact of specifying any particular area as critical habitat. Based upon the previously published proposal to designate critical habitat for the Chorizanthe robusta var. robusta and comments received during the previous comment period, we have prepared a draft economic analysis of the proposed critical habitat designation. The draft economic analysis is available at the above Internet and mailing address.

Public Comments Solicited

We have reopened the comment period at this time in order to accept the best and most current scientific and commercial data available regarding the proposed critical habitat determination for the robust spineflower and the draft economic analysis of proposed critical habitat determination. Previously submitted written comments on this critical habitat proposal need not be resubmitted. We will accept written comments during this reopened comment period. The current comment period on this proposal closes on October 4, 2001. Written comments may be submitted to the Ventura Fish and Wildlife Office in the ADDRESSES section.

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Authority: The authority for this action is the Endangered Species Act of 1973 (16 U.S.C. 1531 et seq.).

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Dated: September 7, 2001.

Daniel S. Walsworth,

Acting Manager, California/Nevada Operations Office.

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[FR Doc. 01-23249 Filed 9-18-01; 8:45 am]