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Home , Artemisia palmeri, California thrasher, Coastal sage scrub, Eryngium aristulatum, Granite night lizard, Heteromeles

3. Biological Resources !

For a complete discussion of the City’s Biological Resources, see the The Biological Resource Report for the City of San Marcos Revised July 11, 1996. Sweetwater Environmental Biologists. Portions of this document are excerpted below. All references cited in Section 3.1 – 3.4.5 can be found in the “Biological Resource Report”.

3.1 Methods The vegetation and sensitive data within the City were mapped and incorporated into SANDAG's Geographic Information System (GIS). The vegetation classification scheme employed was based upon a modified () Holland Vegetation Classification System that was designed to merge the different mapping efforts within the County (City of Carlsbad HMP, County of San Diego, MSCP, Metropolitan Water District of Southern (MWD), and Camp Pendleton.

3.1.2 Existing Information Specific information on the vegetation and sensitive species sightings within the City was gleaned from several sources including over 30 biological resources reports (EIR's, biotechnical reports, etc.); the CNPS's Inventory of Rare and Endangered Vascular (Smith and Berg 1988); Beauchamp's (1988) Flora of San Diego County, California; Bauder's (1986) San Diego Vernal Pools; Recent and Projected Losses; Their Condition; and Threats to Their Existence, Vols. 1 and 2; the San Diego Biodiversity Project's (1991) San Marcos report; and discussions with local experts.

3.1.2 Biological Surveys Field surveys were conducted to verify areas that had been previously mapped, or areas where the vegetation could not be determined from the aerial photographs. These field surveys were limited due to time and were also limited to areas that were easily accessible to the public.

3.1.3 Vegetation Mapping The vegetation within the City and its' Sphere of Influence was mapped on laminated infrared aerial photographs at a scale of 1:24,000 (1 "=2,000') utilizing the following sources. For areas where there was prior vegetation information (EIRs, etc.), this information was incorporated onto these photographs.

The vegetation and sensitive species data were then entered into SANDAG's GIS, generating a biological resource map. This map was then reviewed by John Brown from Dudek and Associates and Fred Sproul from the County of San Diego, as both of these biologists were involved in various mapping projects that overlap with areas within both the City limits and Sphere of Influence of San Marcos.

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3.2 Vegetation Communities There are 12 vegetation communities within the City and the City's Sphere of Influence (Figure 2). The classification scheme used in this report is based upon Holland's Vegetation Classification System modified for San Diego County. The classification system used for San Marcos is consistent with the classification system used for the MHCP. Since much of the information within this report was compiled from other environmental and biological documents, some vegetation types were reclassified so as to be consistent with the MHCP. These decisions were based on the information within these documents and also on site visits by SEB

3.2.1 Scrub Communities Diegan Coastal sage scrub is one of the two major types that occur in California. This habitat type occupies xeric (dry) sites characterized by shallow soils. Sage scrub is dominated by subshrubs whose abscise (fall off) during summer drought and are replaced by a lesser amount of smaller leaves. This adaptation of drought evasion allows these species to better withstand the prolonged drought period in the summer and fall in areas of low precipitation. Sage scrub species have relatively shallow root systems and open canopies. This last trait allows for the occurrence of a substantial herbaceous (non-woody) component in coastal sage scrub. Four floristic associations are recognized within coastal sage scrub formation and these occur in distinct geographical areas along the California coast with the Diegan association occupying the area from Orange County to northwestern coastal (O'Leary 1990).

Coastal sage scrub occurs on a variety of soil types, both chemically and physically, from sandy lithosols on siliceous sandstone to clay-rich chernozems on volcanic ash. Coastal sage have shallow, fibrous root systems, in contrast to the deep penetration root systems of most of the species dominant in adjacent areas. Water is less likely to penetrate to depth in clay soils than in siliceous soils. Clay soils generally lose more moisture through runoff, have lower infiltration rates, store more moisture in an equivalent depth of soil, and are likely to lose a greater proportion of moisture through capillary action and transpiration (water loss) from shallow-rooted species than siliceous soils. Thus, in areas of relatively low precipitation, fine-textured soils are more likely to favor the success of shallow-rooted species rather than deep-rooted species (Kirkpatrick and Hutchinson 1980).

Diegan coastal sage scrub may be dominated by a variety of species depending upon soil type, slope, and aspect. Diegan coastal sage scrub may be classified into several sub-associations based on the dominant species.

The largest contiguous block of Diegan coastal sage scrub within the City occurs on the hills west of Twin Oaks Valley Road, east of Neighborhood One of the College Area Plan and north of Palomar College and San Marcos Junior High School. The sage scrub within this area is dominated by black sage (), California sagebrush (

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californica), and laurel (. laurina). Other sub-associates include flat-top buckwheat, white sage, and coast monkey (Diplacus puniceus). Some of the low lying areas and drainages support dense stands of bush ( ssp. consanguinea) (ERCE 1990; JPF 1988).

A semi-contiguous band of Diegan coastal sage scrub occurs along the slopes that extend from the developed area to the east of Lake San Marcos Country Club, eastward past Discovery Lake and southeast from Discovery Lake to Mt. Whitney. The sage scrub is interrupted by patches of development (the cement plant on Rancho Coronado South and residential development near Mt. Whitney). The component species of this community include California sagebrush, black sage, toyon ( arbutifolia), flat-top buckwheat, and coast monkey flower (MBA 1990a). From Discovery Lake to South Lake (Rancho Coronado South) this community is dominated by black sage and laurel sumac with coyote bush dominant in the sage scrub that is highly disturbed SEB 1992c).

In the southwest comer of the limits of the City (located on and near the University Commons project) there are disjunct patches of Diegan coastal sage scrub. These patches occur from east of Rancho Santa Fe Road and north of San Marcos Creek southeast along Questhaven Road to the San Marcos Landfill. The component species of this community include California sagebrush, flat-top buckwheat, black sage, white sage, laurel sumac and coyote bush (ERCE 1991). This patch was once contiguous with the sage scrub on the southern portion of San Elijo Ranch project. Much of the sage scrub on San Elijo Ranch has been cleared of brush after project certification pursuant to CEQA. The remaining sage scrub habitat is now disjunct from the sage scrub on University Commons. The sage scrub on San Elijo Ranch occurs on the southeast facing slopes of Double Peak. There is also some disturbed sage scrub in the western portion of San Elijo Ranch. California sagebrush, flat-top buckwheat, black sage, and laurel sumac are the dominant species within the sage scrub on San Elijo Ranch (PSBS 1989). Small disjunct patches of sage scrub on the Cielo Azul project and west of Rancho Santa Fe Road along the Carlsbad border are also a part of the sage scrub mosaic in the southwestern comer of the City.

Other small disjunct patches of Diegan coastal sage scrub occur in the central portion of the City (Walnut Hills II; Discovery Hills; the hill between Amorlite Drive and Knoll Road; the hill just east of the intersection of Twin Oaks Valley and Mission roads; and Twin Oaks Valley Ranch.

In the northern Sphere of Influence, a large patch of Diegan coastal sage scrub occurs on the hillsides north of Buena Creek Road, east of Tamara Lane and south and west of Twin Oaks Valley Road.

Diegan coastal sage scrub represents the second largest vegetation community within the BRMP Study Area.

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Diegan Coastal Sage Scrub/Chaparral -Ecotone This community has components of both Diegan coastal sage scrub and southern mixed chaparral. The largest block of this community within the City occurs on the south-facing slopes directly north of Deer Springs Road in the northeastern comer of the City's Sphere of influence. This community is dominated by sage scrub species but has chamise as a dominant component.

Most of the habitat described on the San Marcos Landfill Expansion site is classified as this ecotone. The component species of this community are chamise (), coast white lilac (Ceanothus verrucosus), California sagebrush, laurel sumac, flat-top buckwheat, and black sage (MBA 1990b).

Chapparal Chaparral is the most prominent vegetation type within the regions of California which experience a . Chaparral communities are dominated by evergreen shrubs with small, sclerophyllous ("hard leaved") leaves, which are thick and heavily cutinized to reduce evapo-transpirational water losses. The shrub species characteristic of chaparral communities share other morphological traits including a rigid branching structure and a dual-root system composed of both deep-tap roots and a shallow lateral root system (Rundel 1986). The deep-root systems of chaparral species appear primarily adapted to obtaining moisture from deep recesses, often penetrating into unweathered bedrock (Kirkpatrick and Hutchinson 1980).

Chaparral occurs from sea level to 6,000 feet on rocky, nutrient poor soils and is generally best developed on steep slopes. In coastal areas, chaparral is replaced by in frequently burned areas and by oak woodland on mesic Slopes where fires are infrequent. Chaparral stands form nearly continuous cover of closely spaced shrubs approximately 3-12 feet tall. Herbaceous vegetation is generally lacking within these stands except after fires.

Fire is the dominant environmental factor influencing chaparral vegetation. Acting as a strong selective pressure, fire has selected for two principle methods of regeneration within chaparral plant species: resprouting of aboveground biomass from an underground rootcrown; and the production of that must be scarified prior to germination. The majority of chaparral genera resprout from an underground rootcrown. This is considered to be an ancestral trait among vascular plants (Wells 1969). With the exception of chamise, species that resprout do not produce seeds that are stimulated to germinate following a fire (Rundel 1986). Post fire seedlings of obligate-seeding (growing only from seeds) species arise from a long-lived pool that lies dormant in the soil until germination is cued by either intense heat or a chemical stimulus created by charred wood (Keeley and Keeley 1988). Chaparral is best represented within the City along the southern portion of the City and in the northeast comer of the Sphere of Influence. The two chaparral communities within the City are southern mixed and chamise chaparral. Chaparral represents the largest natural vegetation community within the BRMP Study Area

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Southern Mixed Chaparral Southern mixed chaparral is composed of broad-leaved sclerophyllous shrubs that grow to about 6-10 feet tall and form dense often nearly impenetrable stands. The plants of this association are typically deep-rooted. In this mixed chaparral the shrubs are generally taller (10-20 feet), there is a well-developed soil litter layer, high canopy coverage (>100%). low light levels within the canopy, and lower soil temperatures (Keeley and Keeley 1988). This habitat occurs on dry, rocky, often steep north-facing slopes with little soil. As conditions become more mesic, broadleaved sclerophyllous shrubs that resprout from underground root crowns become dominant.

The largest contiguous block of chaparral within the City occurs along the southern portion of the City from the southwest comer of the City Limits (University Commons project) to the San Marcos/Escondido border. This community is best represented on the slopes of Double Peak, Frank's Peak, and Cerro de las Posas on San Elijo Ranch. This community is dominated by chamise, coast white lilac, mission manzanita (), and laurel sumac. Other important component species include lemonadeberry (), black sage, toyon, Eastwood manzanita (Arctostaphylos glandulosa ssp. glandulosa), and on the north-facing slopes, summer holly (Comarostaphylis diversifolia) (PSBS 1989).

On University Commons the southern mixed/chaparral and Diegan coastal sage scrub are contiguous with the southern mixed chaparral on San Elijo Ranch. Chamise, toyon, mission manzanita, coast white lilac, black sage, and white sage are the primary constituents here (ERCE .1991). From South Lake east to the Escondido border, there are large disjunct patches of southern mixed chaparral that form a mosaic with residential development.

Large patches of southern mixed chaparral occur in the Merriam Mountains in the northern Sphere of influence. The largest patches are directly north of Deer Springs Road and east of Twin Oaks Valley Road; directly south of Deer Springs Road; and on the hillsides south of Twin Oaks Valley Road and north of Buena Creek Road. A disjunct patch of southern mixed chaparral occurs on Meadowlark Estates at the Carlsbad/San Marcos border.

Chamise Chaparral The most widely distributed chaparral shrub is chamise. This species is found from Baja California to northern California in pure or Mixed stands. Chamise's ubiquitous distribution may be the result of being the only chaparral species that regenerates from fire from both an underground root crown and the production of seeds (Rundel 1986; Parker 1984). It often dominates at low elevations and on xeric south-facing slopes with 60-90% canopy cover. Along its lower elevation limit, chamise intergrades with coastal sage scrub (Rundel 1986). Mission manzanita and black sage are minor associates within this community.

Chamise chaparral occurs along the slopes in the southern portion of University Commons and on the lower slopes of the Merriam Mountains on Rose Ranch, along the western

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border of San Marcos. Additional chamise chaparral habitat is likely to occur in the Merriam Mountains in the northwest comer of the City's Sphere of Influence.

3.2.2 Riparian Communities Riparian Forests and Woodlands Riparian forests and woodlands are communities that occur along stream courses and have a distinct stratum. Both riparian forests and woodlands are composed of winter- that require water near the soil surface. Riparian forests have higher canopy area values that result from a high overlap in the canopies of individual trees. Riparian woodlands have lower canopy area values as the canopies of individual trees in this community have lower overlap.

The dominant species that compromise the canopy of riparian forests and woodlands are generally broad-leaved tree species. These species typically have high growth rates, as large surface areas allow for high solar radiation influx and carbon dioxide exchange which is converted into photosynthates. One tradeoff of a large leaf surface area and the accompanying high solar radiation influx is increased leaf temperature. Transpiration (water loss via evaporation ftorn plant surfaces) is a thermo-regulating mechanism designed to maintain a homeostasis. These broad-leaved species are restricted to stream courses because of the need for large amounts of water to maintain low temperatures. Two different sub-associations of riparian woodland were distinguished for the BRMP Study Area: southern riparian woodland and southern coast live oak riparian woodland.

Southern Riparian Forests. The only area identified as a riparian forest within the BRMP Study Area is a small patch (five acres along a tributary of Buena Creek near the western boundary of the City. This community is dominated by species (Salix sp.).

Southern Riparian Woodlands The largest strip of riparian woodland within the City occurs along upper San Marcos Creek from Lake San Marcos east to State Highway 78. The community along this portion of the creek is willow riparian woodland. Arroyo willow (Salix lasiolepis) and black willow (Salix gooddingh) dominate the overstory canopy. Mulefat (Baccharis salicifolia), Douglas mugwort (Artemisia douglasiana), mock parsley (Apiastrum angustifolium), and spike sedge (Eleocharis macrostachya) compose the understory (MBA 1992a).

Along lower San Marcos Creek, between the gorge and Rancho Santa Fe Road, an arroyo willow woodland occurs. Associated understory species include spiny rush (Juncus acutus) mulefat, and San Diego marsh elder ( hayesiana) (ERCE 1991).

A willow riparian woodland dominated by arroyo and black , in association with mulefat and Mexican elderberry (Sambucus mexicana), occurs along the creek on San Marcos Highlands (ERCE 1990). Small disjunct patches of riparian woodlands that are dominated by sycamores (Platanus racemosa) occur along several drainages within the

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City. A sycamore woodland occurs along stream course from South Lake to Discovery Lake. Willows and mulefat occur in association with the sycamores (SEB 1992c). Along Discovery Creek, just below Discovery Lake, several patches of sycamore woodland occur in a mosaic with riparian scrub. Black willow, arroyo willow, coast live oak (), Mexican elderberry, poison oak (Toxicodendron diversilobum), and coyote bush are also components of this community (MBA 1990c).

Several other small disjunct patches of riparian woodland occur throughout the City. Some small disjunct patches of riparian woodland occur along the south side of Deer Canyon road; in the Merriam Mountains, to the northeast of Country Garden Lane; within Twin Oaks Valley; between the Vista/San Marcos border and Linda Vista Drive; and between Meadowlark Estates and The Laurels sites.

Southern Coast Live Oak Riparian Woodland Southern coast live oak riparian woodland is an open, to locally dense, evergreen, sclerophyllous, riparian woodland that is dominated by coast live oak. This community occurs on fine-grained alluvial soils on the floodplains along large streams in the canyons and valleys of coastal (Holland 1986). Associated species may include toyon, Mexican elderberry, spreading snowberry (Symphoricarpos mollis), California rose (Rosa californica), California blackberry (Rubus ursinus), and poison oak.

Southern coast live oak riparian woodland occurs along the stream course that flows along the north side of Twin Oaks Valley Road and at the terminus of Country Garden Lane. Both of these areas are in the northern portion of the City's Sphere of Influence.

Riparian Scrub Riparian scrub communities are shrub dominated communities that occur within stream courses. Riparian scrub communities may not differ in floristic composition from some riparian woodlands but will differ in physiognomy (structure). In many instances, riparian woodland and scrub communities coexist in a mosaic grading into one another. Southern riparian scrub is a generic term for several shrub dominated riparian communities. Southern willow scrub and mulefat scrub are the two riparian scrub communities most common within the City. Both of these communities have been mapped as one entity.

Southern Willow Scrub Southern willow scrub consists of dense, broad-leaved, winter-deciduous stands of trees dominated by shrubby willows in association with mulefat. This habitat occurs on loose, sandy or fine gravelly alluvium deposited near stream channels during flood flows. The herbaceous understory consists of Curly dock (Rumex crispus), cocklebur (Xanthium strumarium var. canadense) and western ragweed (Ambrosia psilostachya). Though floristically very similar to southern willow riparian woodlands, there are differences in physiognomy: southern willow scrub lacks a tree stratum and the lower shrub stratum has higher cover and density values. Frequent flooding maintains this early seral (transitional) community, preventing succession to a riparian woodland or forest (Holland 1986). In the

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absence of periodic flooding, competition between the willows will intensify as these individuals grow and resources become more scarce. A small percentage of these individuals will survive and form the tree stratum, while most will die or exist as suppressed juveniles in the lower stratum.

Areas of southern willow scrub within the City occur along upper San Marcos Creek, east and North of State Highway 78; a small drainage just west of Pacific Street; along the drainage associated with Jack's Pond. on Walnut Hills II; and a small drainage on Meadowlark Estates. Some of these areas had previously been mapped as riparian woodlands, but were subsequently mapped as riparian scrub based on site visits by SEB and the distinguishing criteria elucidated.

Mulefat Scrub Mulefat scrub is a depauperate, tall, herbaceous, riparian scrub community dominated by mulefat and interspersed with shrubby willows. This habitat occurs along intermittent stream channels with a fairly coarse substrate and moderate depth to the water table. Similar to southern willow scrub, this early is maintained by frequent flooding, the absence of which would lead to a riparian woodland or forest (Holland 1986).

Mulefat scrub would be expected to occur within any of the drainages that would support riparian scrub or woodland vegetation, coexisting in a mosaic with these other communities.

Southern Oak Woodlands Southern oak woodlands is a vegetation class that occurs in the outer portion of the central Coast Range and extends south into Baja California. In San Diego County this woodland is best developed in the interior valleys and on gentle foothill slopes of the Peninsular Ranges between 500 and 4,500 feet in elevation. The physiognomy of this woodland typically consists of an overstory which reaches a height of 12-70 feet, incompletely closed, with an understory herbaceous layer approaching 80% cover. Within the Peninsular Ranges, coast live oak and Engelmann oak () are the two codominants. There are several phases within southern oak woodland including coast live oak woodland and Engelmann oak woodland (Barbour 1990). Holland (1986) recognizes several phases within the southern oak woodland including coast live oak woodland, and open and dense Engelmann oak woodlands.

Coast Live Oak Woodland This is an open to dense evergreen woodland dominated by coast live oak which may reach a height of 35-80 feet. This community occurs along the coastal foothills of the Peninsular Ranges; typically, on north-facing slopes and shaded ravines (Holland 1986). The only non riparian oak woodlands within the City occur on San Elijo Ranch. PSBS (1988) did not identify oak woodlands as a community on San Elijo Ranch but considered the oaks as part of the southern mixed chaparral. Weir (1987) classified these areas as oak woodlands. Engelmann oak is an associate of this community also. The shrub and herbaceous layer

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consists of coast white lilac, summer holly, spreading snowberry, and milkmaids (Cardamine californica).

3.2.3 Marsh And Emergent Wetland Communities Marshes are communities that have more or less continuously waterlogged soils dominated by emergent herbaceous plants.

Coastal and Valley Freshwater Marsh Coastal and valley freshwater marsh is dominated by perennial, emergent monocots which reach a height of 12-15 feet. This vegetation type occurs along the coast and in coastal valleys near river mouths and around the margins of lakes and springs. These areas are permanently flooded by fresh water yet lack a significant current (Holland 1986). Much of the freshwater marsh within the City occurs as a mosaic with other riparian wetland communities. Because of the small patch size of much of these communities within the City, not all of these communities have been mapped.

The largest area of freshwater marsh within the City occurs along upper San Marcos Creek from Discovery Street to McMahr Road and from Via Vera Cruz to Echo Lane. Cattails (Typha sp.) and bulrush (Scirpus sp.) are dominant within the areas that are inundated year round with yerba mansa (Anemopsis californica) dominating the vernal meadow areas (M13A 1992a). Along lower San Marcos Creek, south of Lake San Marcos, cattails, bulrush, San Diego marsh elder, and spiny rush are the major constituents. Freshwater marsh occurs sporadically along the unnamed tributary drainage of San Marcos Creek that flows from north of Owen Peak to San Marcos Creek. Yerba mansa, cattails, and spiny rush occur along this drainage between Grand Avenue and San Marcos Boulevard (SEB 1992a). Small patches of freshwater marsh dominated by cattails and bulrush occur along the periphery of Discovery Lake (SEB 1992c); Jack's Pond on Walnut Hills 11 (JP Engineering 1990); the pond and creek channel on San Marcos Highlands (ERCE 1990); along the unnamed tributary of San Marcos Creek that flows through Twin Oaks Valley Ranch (The Planning Associates 1988); and along the unnamed creek that flows from the Atchinson Topeka and Santa Fe Railroad tracks south across Armorlite Drive (J. Messina pers. obs.).

Disturbed Wetlands This community is dominated by exotic wetland species that have invaded sites that have been previously disturbed or undergone periodic disturbances such that these invasive non-natives have displaced the native wetland flora. Characteristic species may include giant reed (Arundo donax), ox tongue (Picris echioides), cocklebur, and tamarisk (Tamarix sp.). Areas within the City that support disturbed wetlands include portions of upper San Marcos Creek in the vicinity of the intersection of Twin Oaks Valley Road and State Highway 78 (MBA 1992a); along portions of the unnamed tributary of San Marcos Creek that flows through Twin Oaks Valley Ranch (The Planning Associates 1988); along portions of the creek channel on San Marcos Highlands (ERCE 1990); along the lake bed, of the ephemeral Discovery Lake (SEB 1992c); the drainage that flows from Bent Ave

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along Broadwalk to Via Vera Cruz (SDBP 1991; SEB 1992b); portions of the vacant lots between Los Vallecitos Boulevard and Echo Lane (J. Messina pers. obs.); and portions of the vacant lot at the southeast comer of the intersection of Las Posas Road and Armorlite Drive (J. Messina pers. obs.). Because of the small size of many of these patches not all were mapped. Approximately 39 acres of disturbed wetlands occur within the San Marcos City Limits and Sphere of Influence.

3.2.4 Communities Native Grassland Native grassland is a community dominated by perennial (native) bunch grasses with annual and perennial forbs such as common components. Native grasslands generally occur on fine-textured soils that generally exclude the annual, exotic grasses. Almost all of the native grasslands in California have been displaced by non-native grassland dominated by introduced annual species. Native grasslands occur throughout California as small isolated islands and in many instances can occur as a mosaic with sage scrub and chaparral communities. Native grasslands were not mapped for the BRMP Study Area because of their small size.

Native grasslands exist in a mosaic with coastal sage scrub on either side of Questhaven Road on University Commons. Purple needle grass (Stipa pulchra), blue-eyed grass ( bellum), blue dicks (Dichelostemma pulchellum), owl's clover (Orthocarpus purpuracens), Weed's mariposa lily (Calochortus weedit) and Orcut’s brodiaea (Brodiaea orcuttii) are the component species of this community on site (ERCE 1991).

Some small patches of native grassland dominated by purple needle grass, blue-eyed grass ripgut grass (Bromus diandrus), and wild oats (Avena barbata) occur on Discovery Hills (Dudek 1991). Some small patches of native grassland also occur on several of the vernal pool sites within the City (Armorlite Drive North, Bent Street, and Pacific Street vernal pools). This community was not mapped separately from non-native grasslands as part of the MHCP.

Non-Native Grassland Non-native grassland is a dense to sparse cover of annual grasses, often associated with numerous species of showy-flowered native annual forbs. This association occurs on gradual slopes with deep, fine-textured, usually clay soils. Characteristic species include oats (Avena sp.), red brome (Bromus rubens), ripgut grass, ryegrass (Lolium sp.), and mustard (Brassica sp.). Most of the annual introduced species that compromise the majority of species and biomass within the non-native grassland originated from the Mediterranean region (an area with a long history of agriculture and a climate similar to California). These two factors, in addition to intensive grazing and agricultural practices in conjunction with severe droughts, contributed to the successful invasion and establishment of these species and the replacement of native grasslands with an annual dominated non-native grassland (Jackson 1985).

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Areas that support annual grasslands within the City include: the vacant lots within the City proper that also support vernal pools (see vernal pool section); upland areas on either side of the riparian vegetation along upper San Marcos Creek; Discovery Hills; and the former pastures from Rose Ranch south to Mission Road.

3.2.5 Vernal Pools Vernal pools are a highly specialized plant habitat that support a unique flora. Vernal pools are associated with two important physical conditions: a subsurface hardpan or claypan that inhibits the downward percolation of water and a topography characterized by a series of low hummocks called mima mounds and low depressions (the vernal pools) which prevents above ground water runoff. As the result of these two physical conditions, water collects in these depressions during the rainy season. As the rainy season ends and the dry season begins, the water that has collected in these vernal pools is gradually evaporated. As water evaporates from these pools a gradient of low soil water availability to high soil water availability is created from the periphery of the pool margins to the center of the pool. The chemical composition of the remaining pool water becomes more concentrated as the pool water is evaporated creating a gradient of low ion concentration at the pool periphery to high ion concentration at the pool center.

A temporal succession of plant species will occur at the receding pool margins, depending upon the physical and chemical microenvironmental. characteristics of the pool. Vernal pools in a wet year will have a high proportion of native species that are endemic to this habitat. During these years the exotic, ruderal species, characteristic of the non-native grasslands that occur on the surrounding mima mounds, will not invade these pools unable to tolerate the physiological conditions of this ephemeral pool. In years of scarce rainfall that is insufficient to saturate the soil and create a surface pool, the native endemic flora will not germinate and the pool will be invaded by the exotic species.

The remaining vernal pools within the City are concentrated downtown in an area that is defined by Pacific Street on the west; Mission road on the north; San Marcos Boulevard on the south; and Twin Oaks Valley Road on the east. Eleven lots within this area support vernal pools. Species composition varies between vernal pools. The characteristic species of vernal pools within the City include grass poly (Lythrum hyssopifolium), toothed downingia (Downingia cuspidata), woolly marbles (Psilocarphus brevissumus), curly dock, rush (Juncus sp.), threadleaved brodiaea (Brodiaea filifolia), Orcutfs brodiaea, San Diego button celery ( aristulatum var. parishii), ditch navarretia (Navarretia fossalis) Crassula aquatica, toad rush (Juncus bufonius), and spike-sedge.

3.2.6 Non-Native Communities Ruderal Vegetation Areas that are highly disturbed are dominated by non-native weedy species that are adapted to a regime of frequent disturbance. Many of the characteristic species of ruderal habitat are also indicator species of annual grasslands, but ruderal areas tend to be more dominated by forbs than by grasses. In California, most of the weedy flora originated from the

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Mediterranean region. Areas that were mapped as disturbed habitat had previously been and were either devoid of vegetation or dominated by ruderal species. Areas that were graded for development were also mapped as disturbed habitat. The large areas within the City that were classified as such were: the areas on San Elijo Ranch project that were cleared of brush, the areas graded for the Scripps Health Care Campus project and Discovery Hills project, and the areas graded for the California State University at San Marcos.

Eucalyptus Woodland Eucalyptus woodland is dominated by eucalyptus (Eucalyptus sp.), an introduced species, that produces a large amount of leaf and bark litter. The chemical and physical characteristics of this litter limits the ability of other species to grow in the understory and floristic diversity decreases. In most instances, eucalyptus are planted for a variety of cultural reasons. If sufficient moisture is available, eucalyptus become naturalized and are able to reproduce and expand their range which has happened in many riparian areas Eucalyptus woodlands occur throughout the City. These woodlands are located on: Rancho Coronado South, north of South Lake (SEB 1992a); along Questhaven Road on San Elijo Ranch (PSBS 1988); the riparian area alongside Twin Oaks Valley Road in the northern portion of the City's Sphere of Influence; alongside the south side of the Atchinson Topeka and Santa Fe Railroad tracks across from San Marcos Junior High School (SEB 1992a); alongside Deer Springs Road; on Rancho Vera Cruz (MBA 1990a); on University Center (RECON 1992); and west of Twin Oaks Valley Road just south of the Vista Siphon Canal.

Orchards Orchards are areas of trees that have been planted, generally in a regular pattern. , olive, , and walnut orchards occur within the City. A high proportion of land within the northern Sphere of Influence is occupied by orchards and the highest concentration of orchards occur here. Large orchards also occur in the southwestern portion of the City between the San Marcos Country Club and both San Elijo Ranch and University Commons. Avocado orchards occur on the southern portion of Meadowlark Estates and continue to the south (JP Engineering 1989). Several large orchards occur on the lower south-facing slopes of Frank's and Double peaks. Another large orchard occurs between Buena Vista Road and San Marcos Highlands in the northwestern portion of the City Limits. Small olive orchards occur on Rancho Vera Cruz (MBA 1990a) and small avocado and walnut orchards occur on Twin Oaks Valley Ranch (The Planning Associates 1998).

Orchards and vineyards represent the third largest vegetation community within the BRMP Study Area.

Agriculture Areas that were designated as agriculture include both crop cultivation and pasture land. In many instances pasture land may be compositionally identical to annual grasslands. The pasture lands in the northern Sphere of Influence appear to be currently active and as such

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retained this classification. Many of the areas south of the intersection of Twin Oaks Valley Road and Deer Springs Road appear to be fallow and for that reason were classified as annual grasslands.

Additionally, there are Urban/developed areas including golf courses, open water, and non-vegetated stream channel occurs within the San Marcos City Limits and Sphere of Influence.

3.3 Wildlife Habitats The classification of the various wildlife habitat types (as opposed to vegetation communities) is based on the California Wildlife-Habitat Relationships prepared jointly by the USDA Forest Service, Pacific Southwest Forest and Range Experiment Station, CDFG, Pacific Gas and Electric Company, and USDA Forest Service Region 5 (1986). This classification system was developed to unify the descriptions being used by USFWS agencies, educators and individual consultants in their analysis and descriptions of the various wildlife habitats encountered in California.

In addition, the interaction of various wildlife species occurs between many different wildlife habitats. This becomes even more evident where these habitats overlap - an area known as an ecotone. These ecotones usually support a combination of the species from the two or more adjoining habitats which generally increases the number and diversity of species within these areas.

3.3.1 Freshwater Emergent Wetlands These areas are characterized by the occurrence of periodic flooding or inundation with fresh water which support a predominance of wetland plants. Coastal and valley freshwater marsh is the only vegetation type within this wildlife habitat association. This habitat is commonly associated with low lying areas which are slow to drain after inundation with fresh water. This habitat has the potential to support more than 160 different species; many of which are dependent on these areas for food and shelter. These habitats function as significant stop over areas for many migrating water fowl.

The largest areas of this habitat type in the City are restricted to portions of San Marcos Creek along several unnamed creeks, and around the edges at Discovery Lake.

3.3.2 Lacustrine Lacustrine habitats include areas of either permanent (lakes, ponds, streams) or temporary inundation (ephemeral creeks, vernal pools) which thus support a distinct flora and allied fauna.

Wetlands are frequented by numerous species of migratory and locally resident including raptors species such as osprey and bald eagle. These areas also support a number of fish, amphibians, and a diverse invertebrate fauna as well as serving as a local congregation point for other vertebrate species. Many of the larger man-made reservoirs

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also serve as an area for recreational fishing, hunting, and boating. Lake San Marcos and Discovery Lake are the two largest examples of this habitat type in the City.

3.3.3 Valley Foothill Riparian/Montane Riparian These habitat types are interspersed along most of the permanent and ephemeral watercourses within San Diego County. Only approximately 40% of these habitats remain within the County (Oberbauer 1991) and most of these are fragmented and/or are found only along the five major rivers within the County. Montane riparian habitat begins to occur above 3,000 foot ASL most often along the western slopes of the Peninsular Range. This riparian habitat differs from the valley foothill riparian habitat primarily in plant and wildlife species composition. Structurally, this habitat may vary from a dominance of uniform shrub-like plant species as is found within floodplain scrub areas to the multilevel canopy type. Commonly the shrub dominated riparian areas are an early successional phase which will progress if not disturbed to the mature multilevel and multi-species mature riparian woodland state. All riparian wildlife habitats are extremely significant biological resources. These habitats support the largest number and greatest diversity of wildlife by providing food, water, migration and dispersal corridors, escape, nesting, and seasonal thermal cover.

San Marcos Creek supports the largest amount of this habitat type within the City. Other significant areas include Buena Creek, the creek on San Marcos Highlands, along Discovery Creek, and along numerous smaller drainages scattered throughout the study area.

3.3.4 Pasture/Annual Grassland These habitats are found over much of the coastal foothill areas secondary to current and historical agriculture. These areas are often dominated by introduced annual grasses and other exotics. Many of these areas were once either native grasslands, dense oak woodlands, or Diegan coastal sage scrub and offer a unique opportunity for research in restoration of these sensitive habitats.

Non-native grassland and ruderal vegetation are two vegetation types that would fit this habitat type. The largest concentrations of pasture/annual grassland are found in the central portion of the City, Discovery Hills, Rose Ranch, and others.

3.3.5 Perennial Grassland This habitat type is similar in its structure and wildlife resources to that of both pasture and annual grassland habitats. The primary differences are that perennial grasslands occur only as isolated remnant patches and contain native bunch grasses and forbs as their dominant plant cover. Throughout California, particularly southern California, this habitat is second most endangered habitat with only approximately six percent of its original area remaining.

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Because of the generally small patch size of perennial grasslands, this habitat was mapped as part of annual grasslands. Known locations include University Commons, Discovery Hills, and several of the areas surrounding vernal pools.

3.3.6 Shrublands encountered west of the Peninsular Range are either Diegan coastal sage scrub, southern mixed chaparral, montane chaparral, charnise chaparral, or southern maritime chaparral. Within southern California, shrublands such as these exhibit high biodiversity. While coastal sage scrub has been reduced considerably in acreage, the chaparral communities of inland San Diego County still exist in large undisturbed tracts which occupy a substantial portion of the eastern county (Oberbauer 1991a).

The shrublands, particularly the chaparral communities, are areas of extremely high biodiversity in terms of invertebrate inhabitants, particularly among various insect groups (Force 1990). A number of species of butterflies and beetles are only found in the chaparral communities of southern California. Vertebrate diversity is also relatively high in this vegetation, especially around areas of rock outcrops. The common bird species found in these shrublands includes California , scrub jay, wrentit, and . These communities also support a number of common such as California pocket mouse, woodrat, brush rabbit, California ground squirrel, striped skunk, coyote, and including western fence , alligator lizard, gopher snake, and rattlesnake.

This is one of the more common habitat types found in the City. The largest blocks of shrublands occur in the Merriam Mountains, Double Peak, Franks Peak, Cerro de las Posas, the hills west of Twin Oaks Valley Road, and east of Neighborhood One of the College Area Plan.

3.3.7 Coastal Oak Woodland More than 300 species of vertebrates are known to utilize oak woodland communities in California for reproduction, foraging, nesting, over-wintering, and during migration (Block et. al 1990); many more species of invertebrates can be expected to occur within this habitat. An important component of oak woodlands are the standing and fallen dead trees which are utilized by numerous species. The structure and composition of both the canopy and understory varies as the terrain, soils, and elevation changes. Coast oak woodlands located along water courses often have dense canopies and understories and are intermixed with typical riparian species. Oak woodlands associated with hillsides and/or spreading valleys are typically more open and have little or no understory except for annual grasses. This habitat is limited to San Elijo Ranch within the study area.

3.3.8 Eucalyptus Woodland These trees were first established in California in 1870 and have been planted extensively since as wind blocks, ornamentals, and hardwood production. Most groves are monotypic with the most common species being either the blue gum or red gum eucalyptus (Eucalyptus sp.). The understory within well established groves is usually very sparse due

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to the closed canopy and allelopathic nature of the leaf litter. As a wildlife habitat these woodlands provide excellent nesting sites for a variety of raptors including golden eagles. During winter migrations a large variety of warblers may be found feeding on the insects that are attracted to the eucalyptus . The sparse understory offers only limited wildlife habitats. The locations of this habitat are the same as the description for eucalyptus woodland in the vegetation.

3.3.9 Rock Outcrops Rock outcrops as a habitat type are a distinctive feature and often found within shrublands, woodlands, and grasslands. The presence of this type of habitat within any given area will considerably enhance the local biodiversity by providing additional microhabitats. Furthermore, the physical properties of the rock itself help moderate microclimates and thus present cooler temperatures than the surrounding vegetated areas during the summer. In San Diego County, rock outcrops in the foothill zone support a distinctive fauna, including such species as the granite , granite spiny lizard, lyre snake, speckled rattlesnake, and northern reddiamond rattlesnake. Various raptor species use these outcrops as nesting and perching sites.

3.4. Sensitive Habitats Sensitive habitats are those which are considered rare within the region, are considered sensitive by CDFG (Holland 1986), support sensitive plants or , or were identified as target habitats by the MHCP. Sensitive species are those species who by circumstance of natural distribution, or through the result of habitat destruction have seen the numbers of their population reach a level so that professional biologists and wildlife managers become concerned about the longevity or vitality of the species. Note: Not all native species are considered sensitive and there are native plants and animals occurring in the City of San Marcos that are widely distributed with stable populations.

3.4.1 Coastal Sage Scrub Coastal sage scrub is considered a sensitive habitat by several resource agencies, including the CDFG (Holland 1986), and is the focus of the NCCP Program because it supports a number of state- and federally-listed endangered, threatened, and rare vascular plants as well as several bird and reptile species that are federally listed or are candidate species for federal listing. Loss estimates for sage scrub habitat in California range from 36-85%.

3.4.2 Riparian and Wetland Habitats Riparian communities and wetlands are also considered sensitive by local, state, and federal agencies. Riparian communities are situated along stream courses and adjacent stream banks. A wetland habitat is defined by certain hydrological, vegetation, and soil criteria.

The EPA and U.S. Army Corps of Engineers define wetlands as: "Those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a

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prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas."

The USFWS defines wetlands as: "...lands transitional between terrestrial and aquatic systems were the water table is usually at or near the surface or the land is covered by shallow water. For purposes of this classification wetlands must have one or more of the following three attributes: (1) at least periodically, the land supports predominantly hydrophytes, (2) the substrate is predominantly undrained hydric soil, and (3) the substrate is nonsoil and is saturated with water or covered by shallow water at some time during the growing season of each year " (Cowardin, et. aL 1979).

Wetland habitat is naturally limited and remaining acreage provide important island habitats for migrant birds. Other important wetland functions include flood conveyance, flood storage, sediment control, providing surface water and insects for fish, amphibians and birds, spawning grounds for aquatic fauna, habitat for rare and endangered species, corridors for wildlife movement, and control of water quality and erosion. Oberbauer (1991a) reports a reduction of 91% of freshwater marsh in San Diego County since the pre-European era. Although it is more difficult to assess changes to this vegetation community because of its generally small patch size, significant reductions within the City have almost certainly occurred.

The functional wetland roles of estuarine and other wetland systems include hydrology, including flood control and shoreline protection; food chain support and nutrient cycling; and provision of habitat for biotic organisms; providing surface water and insects for fish, amphibians and birds; spawning grounds for aquatic fauna; habitat for rare and endangered species; corridors for wildlife movement; and control of water quality and sediment control (Ferren 1990).

Riparian habitat and wetland alteration in southern California has been accomplished by a variety of mechanisms including filling, draining, clearing of vegetation, water diversion projects, impoundment projects, increasing or decreasing nutrient levels within a system, grazing, channelization, increased sediment loading, lowering of water tables, human recreational activities, gravel mining, proliferation of exotic species, grazing and urban development (Bowler 1990). The main drainage within the City, San Marcos Creek, has experienced many of these impacts, including filling, channelization, clearing of vegetation, and introduction of a variety of pollutants.

Many bird species are restricted to riparian habitat and are dependent on it for breeding. Overall wildlife diversity is normally higher in riparian zones than in surrounding habitats. Current estimates of riparian habitat reduction in southern California floodplain areas run as high as 97% (Bowler 1990). Oberbauer (1991a) reports a reduction of riparian woodland in San Diego County of approximately 61%. Similar results have almost certainly, occurred within the City. Additionally much of the remaining habitat has been degraded by

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various human influences. Legislation protecting wetlands has reduced these losses in recent years, including within the city.

3.4.3 Oak Woodlands Oak woodlands are considered sensitive by CDFG (1986) because of their scarcity, high wildlife value, and ability to provide watershed protection. The major factors contributing to the decline of oak woodlands in southern California include livestock grazing, recreational use, and urban and rural development. Because this vegetation type was likely never very common in San Marcos, and many of the areas potentially supporting oak woodland have been developed, impact within the City may have been higher than those experienced county-wide. Scheidlinger and Zedler (1980) report a 13% decline in oak cover during the interval 1928-1970 for southern San Diego County. The largest percentage of decline was in developed areas (17%). The decline in oak populations may accelerate as the large old trees, which make up the majority of these populations, start to die off.

3.4.4 Native Grasslands Native grasslands are one of the most heavily impacted plant communities within San Marcos and California. Many of the pristine native grasslands within the state were converted to nonnative grasslands, dominated by annual grasses from the Mediterranean. This occurred so rapidly after European colonization that there is debate among ecologists as to what the species composition and physiognomy of this community was in a pristine condition. Remaining California native grasslands within San Marcos are not pristine. Native grasslands are considered sensitive by the CDFG (Holland 1986).

3.4.5 Vernal Pools Vernal pools are considered sensitive by CDFG (Holland 1986). Bauder (1987) claims that historical estimates of vernal pool habitat in San Diego County consisted of 28,595 acres. Only 8.7% of that original habitat remained by March of 1979 and 7.2% as of 1986. Between the summer of 1978 and the spring of 1986, 27% of the remaining San Diego County vernal pools were lost to construction projects, and within the next four years an estimated additional 3% of vernal pools will be lost. Between 1978 and 1986, 62% of those pools that occurred on private property and 7% on public property were lost. Construction and vehicle damage are the two greatest threats to vernal pools. Although no detailed estimates were made for the City, a large majority of the area in the central portion of the City had topography and soils conditions appropriate for vernal pools. A large majority of this area has been developed, and all of the undeveloped areas have been at least somewhat disturbed.

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3.5 Sensitive Plant and Species The major known populations of these sensitive species in the City are summarized below. Sensitive Plant and Animal Species

Common Name Scientific Name Known Locations PLANTS San Diego Thornmint Acanthomitha ilicifolia San Marcos Vernal Pools California adolphia Adolphia californica 200 plants within the Southern mixed Chaparral on steep slopes either side of San Marcos Creek, just south of Lake San Marcos. Also, on either side of San Marcos Boulevard near the western city limits. San Diego Sagewort Artemisia palmeri 1,100 plants along Copper Creek drainage. Thread-leaved brodiaea Brodiaea filifolia Over 9,000 plants in the Baldwin Company’s mitigation site, Over 1,000 in the vernal pools. Orcutt’s brodiaea Brodiaea orcuttii Over 15,000 plants in south City. Over 20,000 plants in the vernal pools. Wart-stemmed Ceanothus verrucosus Approx. 2.49 million plants in ceanothus(1) the chaparral communities of south city. Summer holly(1) Comarostaphylis 253,000 in the southern mixed diversifolia, spp. chaparral of south city. Diversifolia Western dichondra Dichondra occidentalis Scattered populations in the coastal sage scrub along San Marcos Creek south of Lake San Marcos. San Diego coyote thistle var. Over 1.000 plants in the vernal parishii pools. Southern spikeweed Hemizonia parryi ssp. Several plants in disturbed australis areas and fresh water marsh habitats along San Marcos Creek. San Diego Marshelder Iva hayesiana Occurs along Copper Creek- San Elijo Hills, San Marcos

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Common Name Scientific Name Known Locations Creek Gorge south of Lake San Marcos. Southwestern Spiny Juncus acutus var. Along San Marcos Creek, San Rush leopoldii Marcos Creek Gorge, and the vernal pools. Orcutt’s linanthus Linanthus orcuttii 50 individuals along a trail at the upper elevations of the north slope of Double Peak. Spreading navarretia Navarretia fossalis 500 plants in the vernal pools. California adder’s- Ophioglossum lusitanicum Three populations on the tongue fern ssp. californicum southern portion of San Elijo Hills (may be extirpated). Englemann Oak Quercus englemannii Several individuals on the north side of Double Peak. Ashy spike-moss Selaginella cinerascens Occurs in most coastal sage scrub and chaparral communities. Parry’s tetracoccus Tetracoccus diocus Rose Ranch Road, San Marcos Mountains. ANIMALS Southwestern pond Clemmys marmorata San Marcos Creek above Lake turtle pallida San Marcos. San Diego horned lizard Phrynosoma coronatum East of Rancho Santa Fe Road blainvillei in the southwestern portion of the City. Coastal whiptail lizard Cnemidophorus tigris Chamise chaparral Mount multiscutatus Whitney and Franks Peak. Northern red-diamond Crotalus ruber ruber San Marcos Highlands. rattlesnake Two-striped garter Thamnophis hammondi The abandoned quarry site on snake San Marcos Creek. Great blue heron Ardea herodias San Marcos Creek. Green-backed heron Butorides striatus San Marcos Creek. Black-crowned night Nycticorax nycticorax San Marcos Creek. heron Turkey Vulture Cathartes aura East and west of Twin Oaks Valley Road and south of Highway 78. Cooper’s Hawk Accipiter cooperi Owen’s Peak, San Marcos Highlands, San Marcos Creek, and Discovery Lake. Sharp-shinned Hawk Accipiter striatus North of Discovery Lake. Northern harrier Circus cyaneus Discovery Lake, Franks Peak.

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Common Name Scientific Name Known Locations White-tailed kite Elanus caerleus leucurus Twin Oaks Valley Road, San Marcos Highlands. Burrowing owl Speotyto cunicularia Vernal pool and grasslands. Coastal California Polioptila californica In the Northern FPA, 3-5 pairs, gnatcatcher californica in the Southern 20-25 pairs. Populations are cyclic, experiencing 30-50% declines in dry years and rebounding in wet years. Blue-gray gnatcatcher Polioptila caerulea San Elijo Hills, Chaparral of South City. Loggerhead shrike Lanius ludovicianus Grasslands west of Twin Oaks Valley Road and south of Hwy 78. Southern California Aimophila rufiaps Franks Peak and Mount rufous-crowned sparrow canescens Whitney, south of Questhaven Road –east of the San Diego Aqueduct. Bell’s sage sparrow Amphispiza belli belli North of Discovery Lake. Grasshopper Sparrow Ammodramus savannarum Grasslands north of Palomar College. Yellow warbler Dendroica petechia Wetland habitat and riparian thickets on Twin Oaks Valley Ranch. White-faced Ibis Plegadis chihi Twin Oaks Valley.

Major populations of Summer Holly and Wart-stemmed Ceanothus in south City have been censused and reevaluated. Please see “Mt. Whitney – Double Peak Sensitive Chaparral Species Population Estimate”, Dames and Moore, October 27 1999. See Appendix.

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