_Artemisia californica_
_Salvia apiana_
_Salvia mellifera_
_Eriogonum fasciculatum_
_Rhus integrifolia_
_Opuntia occidentalis_
_Haploppapus squarrosus_
This association is restricted to the Pacific base of the range, is
typical on the alluvium at the bases of the coastal foothills, and
usually grades into the chaparral at about 1800 feet elevation. When
seen from above, the rather level terrain of the association is broken
sharply at the mouths of canyons by dry washes, and is limited below, to
the south, by cultivated land. The coastal sagebrush is the most
characteristic plant of this association, occurring in all undisturbed
parts of the area.
There are several habitats within the coastal sage scrub association.
These differ from one another chiefly on the basis of soil type. The
soil of the rather level sageland in most places is rocky or gravelly,
or, as adjacent to washes, it is finely sandy in texture, and supports
the major plants of the association. Most of the eroded adobe banks at
the bases of the foothills support these same plants, with white sage
being the dominant species. Locally, as in damp hollows or cleared
areas, there is grassland. Jumbles of boulders, sand, gravel, and steep
cutbanks, are characteristic of the channels of dry washes, these areas
supporting sparse vegetation. The fauna and flora of the washes are
distinct from those of surrounding sage flats. Because they are included
within the geographic limits of the coastal sage belt, however, the
washes are discussed along with this association.
The abruptness with which one habitat gives way to another in this
association causes sharp dividing lines between the local ranges of
certain mammals. For example, in trap lines transecting dry washes and
level sageland two assemblages of rodents were found. That part of the
line amid the boulders and cutbanks of the wash took mostly
_Peromyscus eremicus fraterculus_ and _Neotoma lepida intermedia_, while
_Perognathus fallax fallax_, _Dipodomys agilis agilis_, and _Peromyscus
maniculatus gambeli_ were taken in the adjacent sage flats. The steep
adobe slopes of the foothills, which constitute the upper part of the
coastal sage scrub association, are commonly inhabited by _Peromyscus
californicus insignis_, which rarely occurs in the level tracts of sage
a few yards away. Thus, this association is not homogeneous with regard
to its rodent population; many of these species have local and
discontinuous distributions.
The following list gives the results of about 500 trap nights (a trap
night equals one trap set out for one night) in typical coastal
sage-scrub association one-half mile southwest of the mouth of San
Antonio Canyon, at 1700 feet elevation.
TABLE 2.--YIELD OF 500 TRAP-NIGHTS IN THE COASTAL SAGE SCRUB
ASSOCIATION.
======================================================================
| Number | Per cent
| | of total
--------------------------------------------------+--------+----------
Perognathus fallax fallax | 31 | 30.7
Dipodomys agilis agilis | 20 | 19.8
Reithrodontomys megalotis longicaudus | 4 | 4.0
Peromyscus californicus insignis | 4 | 4.0
P. eremicus fraterculus | 7 | 6.9
P. maniculatus gambeli | 20 | 19.8
Neotoma lepida intermedia | 9 | 8.8
N. fuscipes macrotis | 2 | 2.0
Microtus californicus sanctidiegi | 4 | 4.0
--------------------------------------------------+--------+----------
The list below indicates the catch in 200 trap nights in San Antonio
Wash, at 1700 feet elevation and within the realm of the coastal sage;
all of the traps were set in rocky and sandy main channels of the wash.