Regularity: Regularly occurring
Global Range: Only known from Mt. Diablo area, Contra Costa County, California; 500-2000 ft. The range covers 5 quads, which equals approx. 260 sq mi.
Comments: Chaparral on sandstone.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 6 - 20
Comments: There are 19 known occurrences in May 2005 (CNDDB).
National NatureServe Conservation Status
Rounded National Status Rank: N2 - Imperiled
NatureServe Conservation Status
Rounded Global Status Rank: G2 - Imperiled
Reasons: This California endemic is known from at least 18 extant and one extirpated population. Overall there probably are about 26,000 individuals left. Various factors threaten this species, but fire suppression and off-trail use are the most common. Fire has been observed to play a role in maintaining good stands of this plant, but research is needed.
Environmental Specificity: Very narrow. Specialist or community with key requirements scarce.
Comments: This manzanita occurs on sandstone, but only in one small part of the state and the world. It is not really understand why it is so restricted, but the fact remains that it is.
Global Short Term Trend: Decline of 10-30%
Comments: Although several occ's are protected on State Park or other park lands, the trend has very likely still been down over the past 10 years.
Global Long Term Trend: Decline of 30-50%
Degree of Threat: High
Comments: Nearly all occurrences of this Californian endemic are threatened by some factor. The various threats that exist are brush clearing, grazing, road maintenance, development, slash burning, vandal fires, dumping, off-trail use and fire suppression. The most common threats are fire suppression and off-trail use (CNDDB 2003).
Biological Research Needs: Need for fire? - One population in Contra Costa county was burned by the Black Hawk fire of 1981 and many seedlings sprouted afterwards; this site was later reported to have an almost pure stand.
Arctostaphylos auriculata (Mount Diablo Manzanita) is an endangered species of Arctostaphylos endemic to California, and limited in geography to the area surrounding Mount Diablo, in Contra Costa County.
Arctostaphylos auriculata is a woody shrub 1-4.5 m high with serpentine, glandless stems covered in white hair. The short [1.5-4.5 cm], silvery leaves overlap and have deeply lobed bases. It flowers densely in white February through May. The fruit is also hairy and small (5-10 mm). The Mount Diablo Manzanita has no basal burl for regrowth and must propagate by seed.
- California chaparral and woodlands
- California montane chaparral and woodlands
- California interior chaparral and woodlands
- W. L. Jepson. 1951. A Manual of the Flowering Plants of California, p. 750.
- Coffey, Geoffrey. "Sympathy for the devil -- tricks and treats on Mount Diablo." San Francisco Chronicle 25 Oct. 2003 : E-7.
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