Endangered and Threatened Wildlife and Plants; Withdrawal of Proposed Rule to List Arctostaphylos Imbricata (San Bruno Mountain Manzanita) as Threatened

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN: 1018-AC98

Endangered and Threatened Wildlife and Plants; Withdrawal of

Proposed Rule to List Arctostaphylos Imbricata (San Bruno Mountain

Manzanita) as Threatened

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule; withdrawal.

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SUMMARY: The U. S. Fish and Wildlife Service (Service) withdraws the

proposal to list Arctostaphylos imbricata (San Bruno Mountain

manzanita) as a threatened species under the Endangered Species Act of

1973, as amended (Act). This determination is based on evaluation of

comments and additional information received subsequent to publication

of the proposed rule. Provisions of the San Bruno Mountain Habitat

Conservation Plan (HCP) pertaining to management for the conservation

of A. imbricata have been clarified. Other threats identified in the

proposed rule pertaining to fire frequency and overutilization for

horticultural purposes are no longer considered to pose a significant

risk to the survival of the species. Thus, protection under the Act is

unnecessary at this time.

ADDRESSES: The complete file for this rule is available for public

inspection, by appointment, during normal business hours at the

Sacramento Field Office, U.S. Fish and Wildlife Service, 3310 El Camino

Ave., Sacramento, California 95821-6340.

FOR FURTHER INFORMATION CONTACT: Diane Windham, at the above address or

by telephone at (916) 979-2725.

SUPPLEMENTARY INFORMATION:

Background

Alice Eastwood (1931) originally described Arctostaphylos imbricata

in 1931, based on material collected from the San Bruno Hills in 1915.

Until 1967, various authors either synonymized A. imbricata with A.

andersonii (Jepson 1939), or considered it to be a variety of A.

andersonii (Adams in McMinn 1935). Roof (1967) followed Eastwood's

treatment and acknowledged A. imbricata as a distinct species. Wells

(1988) recognized A. montariensis as a subspecies of A. imbricata

which, under the rules of botanical nomenclature, automatically created

the name (autonym) A. imbricata ssp. imbricata. He has since revised

his treatment of California Arctostaphylos to recognize A. imbricata as

a distinct species (Wells 1993).

Arctostaphylos imbricata is a low, spreading, evergreen shrub of

the heath family (Ericaceae) that lacks a basal burl. Attaining a

height of 20 centimeters (8 inches), this highly branched shrub forms

mats up to about 6 meters (m) (6 yards) in diameter. The bright green,

oblong to ovate leaves are hairless, except on the midrib, and densely

overlapping. Small, white, urn-shaped flowers appearing from February

to May are densely clustered at the end of branchlets. After fire, A.

imbricata regenerates from seed instead of resprouting from a basal

burl. Arctostaphylos imbricata can be distinguished from other members

of the genus by its prostrate form, its shorter, densely arranged

leaves, and its compact flower clusters (Roof 1967).

Arctostaphylos imbricata is restricted to San Bruno Mountain in

northern San Mateo County. On San Bruno Mountain, six small colonies

comprise one population which covers approximately 2.3 hectares (5.6

acres) (V. Harris, Thomas Reid Associates, in litt. 1993; R. Gankin,

San Mateo County Planning Department, in litt. 1994). The most abundant

colony has 400 to 500 plants; other colonies have as few as 3 plants

(R. Gankin, pers. comm. 1993; R. Gankin, in litt. 1994). The plant

grows on rocky, exposed areas such as open ridges within coastal scrub

or manzanita scrub vegetation at an elevation range of 275 to 365 m

(900 to 1,200 feet). Where it occurs, it is the dominant plant species,

and may be associated with Baccharis pilularis (coyote brush),

Vaccinium ovatum (huckleberry), Rhamnus californica (coffeeberry), and

Arctostaphylos uva-ursi var. suborbiculata (bearberry) (California

Department of Fish and Game 1988). Arctostaphylos imbricata has never

been known from more than the single population of six colonies that

occurs today. Five of the six colonies occur on land owned by the San

Mateo County Department of Parks and Recreation; the sixth colony is

privately owned (Thomas Reid Associates 1991). All colonies are located

within the San Bruno Mountain HCP boundaries.

Finding and Withdrawal

The proposed rule to list Arctostaphylos imbricata as threatened

(October 4, 1994; 59 FR 50550), stated that the San Bruno Mountain HCP,

a planning effort under management and implementation by San Mateo

County and their consultant, Thomas Reid and Associates, identifies A.

imbricata as a ``species of concern'' but that the HCP does not

identify any species-specific management actions for this species.

Since publication of the proposed rule, provisions of the HCP

pertaining to management for the conservation of A. imbricata have been

clarified. The HCP preserves most of the mountain and provides

monitoring and management for a number of rare plant and animal

species, including A. imbricata. In addition, threats identified in the

proposed rule pertaining to fire frequency and overutilization for

horticultural purposes are no longer considered to pose a significant

risk to the survival of the species. For these reasons, the Service now

believes the plant is adequately conserved.

Previous Federal Action

On December 15, 1980, the Service published in the Federal Register

an updated Notice of Review for plants

(45 FR 82480) which included Arctostaphylos imbricata as a category 1

candidate for Federal listing. Category 1 taxa were formerly defined as

taxa for which the Service had on file sufficient information on status

and threats to support issuance of a listing proposal. Arctostaphylos

imbricata retained category 1 status in revised plant notices published

on September 27, 1985 (50 FR 39526), February 21, 1990 (55 FR 6184),

and September 30, 1993 (58 FR 51144).

A proposal to list Arctostaphylos imbricata as threatened and

Lessingia germanorum as endangered was published in the Federal

Register on October 4, 1994 (59 FR 50550). This notice of withdrawal of

the proposal to list A. imbricata is published concurrently in the

Federal Register with the final rule listing L. germanorum as

endangered in order to resolve the listing status of both species.

Processing the final listing decisions on these two species follows the

Service's listing priority guidance published in the Federal Register

on December 5, 1996 (61 FR 64475).

Summary of Comments and Recommendations

In the October 4, 1994, proposed rule and associated notifications,

all interested parties were requested to submit factual reports or

information

[[Page 33389]]

that would contribute to the development of a final decision document.

Appropriate Federal and State agencies, county and city governments,

scientific organizations, and other interested parties were contacted

and requested to comment. In accordance with Service policy published

on July 1, 1994 (59 FR 34270), the Service solicited comments from

three appropriate and independent specialists regarding pertinent

scientific or commercial data and assumptions relating to the proposed

rule. A newspaper notice of the proposed rule was published in the San

Francisco Chronicle on October 19, 1994, which invited general public

comment. A 60-day comment period closed on December 4, 1994.

The Service received eight letters of comment. No requests for

public hearings were received. Because the proposed rule included both

Arctostaphylos imbricata and Lessingia germanorum, only comments

pertaining to A. imbricata are discussed here. Comments and issues

pertaining to L. germanorum are discussed in a separate Federal

Register notice published concurrently with this notice.

Of the eight people who submitted comments, three were neutral and

four supported the listing of Arctostaphylos imbricata. The eighth

respondent opposed the listing of A. imbricata on the grounds that

listing was premature at the time and recommended that it be retained

as a candidate species. As previously indicated, the listing proposal

for A. imbricata is being withdrawn in this notice. A candidate is a

species for which the Service has on file sufficient information on the

status and threats to the species to support issuance of a listing

proposal. Therefore, upon the withdrawal of the proposal to list, A.

imbricata cannot be maintained as a candidate.

One commenter indicated that designation of critical habitat would

aid in protection of rare plants. Because the proposed rule for

Arctostaphylos imbricata is being withdrawn, this issue is moot with

respect to this species. Another commenter suggested that the effects

of microwave facilities on San Bruno Mountain might pose a threat to

the species. The Service is not aware of any data to support this

contention and no evidence was provided by the commenter.

The combined threats of senescence (growing old, dying) of plants

and lack of reproduction due to the prolonged absence of fire described

in the proposed rule were considered by another commenter to be

unsubstantial. After reviewing the available information, the Service

concurs. More detail on this issue is provided in the discussion of

Factor E in the ``Summary of Factors Affecting the Species'' section

below.

Only one of the three independent and appropriate specialists

provided comments on the proposal to list Arctostaphylos imbricata.

This reviewer concurred with all of the comments made in the proposed

rule concerning the status, threats, and potential threats to the

species and supported listing as proposed. The reasons for the

Service's decision to withdraw its proposal to list A. imbricata, in

opposition to this specialist's recommendation, are explained in the

following section.

Summary of Factors Affecting the Species

Section 4(a)(1) of the Act requires the Service to consider five

factors when determining whether to list a species as threatened or

endangered. These factors, and their application to the Service's

decision to withdraw the proposal to list Arctostaphylos imbricata

Eastw. (San Bruno Mountain manzanita), are as follows:

A. The present or threatened destruction, modification, or

curtailment of its habitat or range. No threats to Arctostaphylos

imbricata were identified under this factor in the proposed rule, nor

were any such threats identified by commenters on the rule. None of the

colonies are threatened by development permitted under the San Bruno

Mountain HCP. The Service believes that no threats exist to the

species' habitat or range.

B. Overutilization for commercial, recreational, scientific, or

educational purposes. The proposed rule cited overutilization for

horticultural purposes as a potential threat to Arctostaphylos

imbricata. In 1991, cuttings were taken from plants located at

Kamchatka Point on San Bruno Mountain. The remnant surviving portions

of the plants showed evidence that the clippings were performed with

horticultural expertise (Doug Heisinger, Park Ranger, San Mateo County

Park, pers. comm. 1993). Some A. imbricata individuals being sold at

local plant sales may have originated from clippings from the natural

population (Paul Reeberg, pers. comm. 1993). The Service now concludes

that, although such actions are inappropriate and illegal (under both

the California Endangered Species Act and the California Native Plant

Protection Act), infrequent pruning does not currently constitute a

significant threat to the survival of the species.

C. Disease or predation. No known threats from disease or predation

were identified in the proposed rule. The Service has no new

information on threats from these factors.

D. The inadequacy of existing regulatory mechanisms. The proposed

rule stated that Arctostaphylos imbricata derived limited protection

from the San Bruno Mountain HCP, but that no species-specific

management actions for A. imbricata are identified in the HCP and none

have been implemented. After publication of the proposed rule, the HCP

Trustees informed the Service that the San Bruno Mountain HCP provides

for monitoring and management of populations of all rare plants

occurring on the mountain including A. imbricata. Moreover, the HCP

Trustees have agreed and committed to an annual budget for rare plant

monitoring and management. Any specific management activities

recommended, such as controlled burning (see Factor E below), will be

carried out under the HCP. Present management for A. imbricata includes

alien plant control. The Trustees have also expressed a willingness to

meet and work with Service biologists to identify and implement any

specific management actions necessary for the conservation of the

species (V. Harris, in litt. 1996).

Arctostaphylos imbricata is listed as endangered under the

California Endangered Species Act (Chapter 1.5 section 2050 et seq. of

the California Fish and Game Code and Title 14 California Code of

Regulations 670.2). The proposed rule stated that, although both the

California Endangered Species Act and the California Native Plant

Protection Act prohibit the ``take'' of State-listed plants (California

Endangered Species Act, Chapter 1.5 section 2080 and California Native

Plant Protection Act, Chapter 10 section 1908), State law exempts the

taking of such plants via habitat modification or land use changes by

the owner provided notification requirements are satisfied. The Service

concluded that this exemption renders State law inadequate to protect

A. imbricata from extinction. The Service believes that the inadequacy

of State law in protecting A. imbricata is no longer an issue because

protection of the species is provided by the San Bruno Mountain HCP.

E. Other natural or manmade factors affecting its continued

existence. The Service indicated in the proposed rule that

Arctostaphylos imbricata is a fire-adapted plant that, following a

fire, regenerates entirely from seed and does not resprout from a basal

burl. Keeley (1977) labeled plants employing this

[[Page 33390]]

type of post-fire reproductive strategy ``obligate-seeders.'' The

Service also implied in the proposed rule that fire, which can remove

competing vegetation and counter mechanisms that prevent seed

germination (e.g., hormones, impervious seed coat), is necessary for

the maintenance of A. imbricata because sexual reproduction by seed is

important to the maintenance of genetic diversity. Although germination

of its seed bank (seeds accumulated in the soil and canopy of mature

shrubs) is triggered mainly by fire, occasional germination and

establishment of A. imbricata does occur without the aid of fire (R.

Gankin, in litt., 1994). Moreover, A. imbricata can spread vegetatively

and reportedly is spreading on San Bruno Mountain (R. Gankin, in litt.,

1994). Thus, fire is not necessary for maintenance of the species.

The Service asserted in the proposed rule that if the amount of

time between fires were too long, Arctostaphylos imbricata would have

little opportunity to reproduce sexually and individuals could become

senescent. However, Keeley (1977) argued that the reproductive strategy

of obligate-seeders such as the non-sprouting manzanita species is an

adaptation to a long-interval fire cycle. Obligate-seeders tend to

occur in less fire-prone areas, like San Bruno Mountain which is often

shrouded in fog during the summer (D. Schooley, Bay Area Land Watch, in

litt., 1994), that generally burn more intensely when fires do occur

(Keeley 1977). Consequently, A. imbricata and other obligate-seeders

``are resilient to very long intervals [between fires] and successful

seedling recruitment is observed after fires in stands which may exceed

100 years of age'' (Keeley et al. 1988). In addition, fires burned

colonies of A. imbricata on San Bruno Mountain in 1964 and in the late

1980's. Even though all of the individuals in the colony which burned

in the 1980's were killed, significant regeneration did take place (R.

Gankin, in litt., 1994). Also, both regeneration from seed and

spreading by layering has occurred in the colony which burned in 1964

(D. Schooley, in litt., 1994). For these reasons, the Service concludes

that the prolonged absence of fire does not threaten A. imbricata now

and will not in the foreseeable future.

The Service also stated in the proposed rule that a reduction in

fire frequency could pose a threat to the species because periodic

fires reduce competition and shading by other plant species. On San

Bruno Mountain, Arctostaphylos imbricata grows on rocky exposed areas

such as open ridges. On such sites, the lack of soil development

precludes significant establishment of other plant species; the species

most likely to pose a threat through overtopping and consequent

shading, Ceanothus thrysiflorus, is a short-lived species that does not

do well on such undeveloped soils (R. Gankin, in litt., 1994). The

Service now concludes, on the basis of the foregoing evidence, that the

prolonged absence of fire is not likely to result in significant

establishment of other plant species and that therefore competition

from (including shading by) other plant species does not pose a

significant threat to the survival of A. imbricata.

Frequent fire, that is fire recurring within a short period of time

(fewer than 15 years), can result in local extinctions (Zedler et al.

1983 in Keeley and Keeley 1988). As discussed above and in the proposed

rule, on San Bruno Mountain Arctostaphylos imbricata grows on rocky

exposed areas such as open ridges. Because such open sites lack

sufficient fine fuels (i.e., dried grass and herbs) to sustain fire or

carry fire from adjoining, more densely vegetated habitat, the Service

concludes that fire is unlikely to occur frequently in A. imbricata

habitat and that, therefore, frequent fire is not a significant threat

to the species.

The Service has carefully assessed the best scientific and

commercial information available regarding the past, present, and

future threats faced by Arctostaphylos imbricata in determining to

withdraw the proposed rule to list the species as threatened. The

Service has determined that implementation of the San Bruno Mountain

HCP, which includes monitoring and management of A. imbricata,

sufficiently removes the threats to the species and provides for its

conservation. Furthermore, the Service has determined that the threats

identified in the proposed rule pertaining to fire frequency and

overutilization for horticultural purposes are not likely to pose a

significant risk to the survival of A. imbricata.

Author: The primary author of this document is Diane Windham,

Sacramento Field Office (see ADDRESSES section).

Authority: The authority for this action is section

4(b)(6)(B)(ii) of the Endangered Species Act of 1973, as amended (16

U.S.C. 1531 et seq).

Dated: April 8, 1997.

John G. Rogers,

Acting Director, U.S. Fish and Wildlife Service.

[FR Doc. 97-15926 Filed 6-18-97; 8:45 am]

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