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Appendix B:
Biotic Resources
B.1 Plants
B.2 Wildlife
B.1 Plants
Source: Jennifer Mitamura 2008
Appendix B: Biotic Resources
on ecosystematic design, which may help explain why project area
plants and wildlife were examined with such specificity (Lyle 1999). In
addition, the Los Angeles Region, with its elevated level of biodiversity
lying adjacent to a complex urban infrastructure, offers a prime area to
focus conservation and preservation areas.
Figure B.1-1, Sycamore Tree along the San Gabriel Foothills
The Los Angeles region is rich in natural resources. Lying between
the tall peaks of the San Gabriel Mountains and the Pacific Ocean, the
area’s plant and wildlife communities are as diverse as its topography.
The region’s Mediterranean-type climate creates not only cool,
moist areas in the coastal canyons but also more semi-arid and dry
conditions inland. Plant species range from water-needy riparian trees
such as native willows and California sycamore (Platanus racemosa)
to the more drought-tolerant species such as those found within
the chaparral or coastal sage scrub communities (see Figure B.1-1,
Sycamore Tree along the San Gabriel Foothills). Wildlife dependent on
these plants are equally as varied. The region is home to seven species
of hawks, eight species of owls, peregrin falcons, golden eagles whitetailed kites (Santa Monica Mountains Conservancy 2008)
and other avian species.
John T. Lyle, in his book Design for Human Ecosystems, calls for a
method of land-use planning that enables natural and human
systems to co-exist. The Emerald Horseshoe Concept Plan is based
174
Historical Plant Communities
The pre-development landscape was much different from what exists
in the Emerald Horseshoe project area today. In the upper watersheds,
the majority of the land was covered with shrub-dominated chaparral,
patches of mixed hardwood/conifer woodlands, and strips of riparian
vegetation along the watercourses (United States Army Corp of
Engineers 2005). On the south-facing slopes of the foothills, a variety
of shrub communities existed, such as Coastal Sage Scrub and
Chaparral. On the shadier slopes and along the canyon floors, Oak
and Walnut Woodlands flourished. In some foothill areas, near where
the Arroyo Seco and Eaton Wash exited the mountains, alluvial fan
sage scrub dominated, supported by the periodic flooding of the
watercourses. Down in the valley, grasslands made up of perennial
bunchgrasses, annual grasses, and herbs thrived. Alder, willow, and
sycamore trees once stood along the banks of the Arroyo Seco and
Eaton Wash. Near the confluence of the Los Angeles River and the
Arroyo Seco, Southern California Black Walnut Woodlands once
prevailed. This plant community is currently in decline throughout its
Southern California range. (Arroyo Seco Foundation 2003) (Figure B.12, Historical Plant Communities).
Existing Vegetation Locations
Today, development and ornamental landscapes have taken over
almost the entire project area allowing ruderal non-native species
to thrive, resulting in isolated patches of native vegetation that was
once substantial habitat (City of Pasadena 2003). Along the Arroyo
Seco, stands of California black walnut (Juglans californica) still remain,
although patchy and disconnected. Non-native invasive species
make their way up the length of the river; their growth aided by the
st
Tra
il
Source: Wieslander 1900
A
ash
Eaton W
o
Sec
yo
rro
Figure B.1-2, Historical Plant Communities
Scale: NTS
Black Sage, California Sage,
Chamise, Scrub Oak
Douglas Fir
Coast Live Oak, Cultivated Riparian
Grass
Project Area
N
Appendix B: Biotic Resources
Altadena Cre
continual disruption of the urban environment such as increased
nitrogen deposition, air pollution, and ornamental planting. Closer to
the mountains, the habitat begins to diversify and birchleaf mountain
mahogany (Cercocarpus betuloides), California sagebrush (Artemisia
californica), coast live oak (Quercus agrifolia), and scrub oak (Quercus
berberidifolia) appear. The trapped water behind Devil’s Gate Dam
feeds riparian-mixed hardwood species such as California sycamore
(Platanus racemosa) (Figure B.1-3, Existing Vegetation Types, Arroyo
Seco). Angeles National Forest, in the upper reaches of the project
area, offers the most substantial source of continuous vegetation. The
area along the Altadena Crest Trail holds significant stands of coast live
oak, scrub oak, canyon live oak (Quercus chrysolepis), and various types
of chaparral and sage scrub. As Eaton Wash surfaces at the eastern
end of Altadena Crest Trail, California sycamores begin to emerge and
make their way down the wash (Figure B.1-4, Existing Vegetation Types,
Altadena Crest Trail). The project area, as it runs along Eaton Wash,
is devoid of much vegetation aside from non-native grasses, forbs,
ornamental grasses, scrubs, and hardwood species. There are also
various nurseries that lay on the western side of the wash (Figure B.15, Existing Vegetation Types, Eaton Wash).
Existing Plant Communities
There are nine plant communities within the Emerald Horseshoe
project area. The diversity of these vegetation types is not only
dependent on elevation, but soil type and precipitation as well (see
Figure B.1-6, Plant Communities Profile).
Bigcone Spruce-Canyon Oak Forest
Bigcone Spruce-Canyon Oak Forest is found in the upper reaches of
the watershed where annual rainfall is high. This plant community is
dominated by the bigcone spruce (Pseudotsuga macrocarpa) with a
subcanopy of canyon oak (Quercus chrysolepis). Shrubs are infrequent
within this community and the ground layer is typically sparse. The
continuous canopy of this plant community is helpful in slowing and
filtering rainfall. Within a chaparral matrix, as that found along the
Altadena Crest Trail, stands of Bigcone Spruce-Canyon Oak Forest
Emerald Horseshoe Concept Plan
175
B.1 Plants
A
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oS
oy
o
ec
d
Arca
0
176
1
N
Figure B.1-4, Existing Vegetation Types, Altadena Crest Trail
2 Miles
0
0.5
N
R io
Figure B.1-5, Existing Vegetation
Types, Eaton Wash
0
1 Miles
1
do
Hon
Data from: FRAP 1997
Data from: FRAP 1997
Data from: FRAP 1997
A
h
as
ia W
iver
Figure B.1-3, Existing Vegetation Types,
Arroyo Seco
ash
oW
R
sh
Wa
ra
mb
ele
s
a
Alh
ng
os A
L
ash
Eaton W
o
Sec
yo
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Ru b i
Appendix B: Biotic Resources
Eat
as h
on W
N
2 Miles
Agriculture
California Sagebrush
Interior Mixed Hardwood
Scrub Oak
Annual Grasses/ Forbes
California Sycamore
Lower Mountane Mixed Chaparral
Soft Scrub Mixed Chaparral
Baccharis
California Walnut
Mixed Conifer
Sumac Scrub
Barren/ Rocks
Canyon Live Oak
Non-Native Ornamental
Upper Montane Mixed Chaparral
Bigcone Douglas Fir
Ceanothus Mixed Chaparral
Perennial Grass
Urban
Birchleaf Mountain Mahogany
Coast Live Oak
Riparian Mixed Hardwood
Water
Buckwheat
Coastal Cactus
Riversidean Alluvial Fan Sage Scrub
Rivers & Tributaries
California Bay
Eucalyptus
Project Area
Soil
10,000’
25”-40”
Clay to Granite
pH up to 7.8
8,000’
15”-30”
Granitic, Metamorphic Rocks
Mixed with Sandy Loam, pH 5.2-5.5
6,000’
Snow Line
Coast Live
Oak Woodland
Sandy Loam, pH 5.6-7.3
4,000’
Young Alluvium
and Silty Sand
2,000’
Chamise Chaparral
Sage Scrub
5-15”
Mule Fat Scrub
Southern Willow Scrub
Southern
Sycamore-Alder
Riparian Woodland
North
Figure
B.1-6,Sawyer
Plantand
Communities
Profile
Data from:
Keeler-Wolf 1997
remain small, making it a key plant community to focus conservation
and restoration efforts (see Figure B.1-4, Existing Vegetation Types,
Altadena Crest Trail) (Sawyer, Keeler-Wolf 1995, City of Pasadena 2003,
Sapphos Environmental 2006, Keeley 2002).
Coast Live Oak Woodland
On the shadier slopes and interior canyons Coast Live Oak Woodlands
flourish. Coast live oak (Quercus agrifolia) is often the sole or dominant
tree species in the canopy, which can be contiguous, irregular, or
Riversidian
Alluvial Fan
Sage Scrub
Ruderal
Nonnative
Grasslands
South
Data from: Sawyer and Keeler-Wolf 1997
Bigcone
Spruce
Elevation
open depending on the
density of the other species
within the community such
as coast live oak, bigleaf
maple (Acer macrophyllum),
or California bay laurel
(Umbellularia californica).
Coast Live Oak Woodlands
mix with Coastal Sage Scrub
and Chaparral on drier sites,
and are typically found on
steep slopes or raised stream
banks and terraces (see Figure
B.1-3, Existing Vegetation Types,
Arroyo Seco and Figure B.14, Existing Vegetation Types,
Altadena Crest Trail). This plant
community is home to a
variety of wildlife species,
including the Cooper’s hawk
(Accipiter cooperii), one of the
Emerald Horseshoe Design
species (see Table B.1-1,
Wildlife Design Species Matrix)
(Sawyer, Keeler-Wolf 1995, City
of Pasadena 2003, Sapphos
Environmental 2006, Keeley
2002).
Appendix B: Biotic Resources
Precipitation
(inches/year)
Chamise Chaparral, Coastal Sage Scrub, Mule Fat Scrub
Further down slope, near streams, Chamise Chaparral turns into
mixed Coastal Sage Scrub, and Mule Fat Scrub. Chaparral and Coastal
Sage Scrub plant communities. These communities are a mixture of
fire-adapted, hard-leaved, woody species found on dry, rocky, steep,
south-facing slopes and ridges with shallow soils. Generally, shrubs are
6- to 10-feet tall. Along the Altadena Crest Trail, chamise (Adenostoma
Emerald Horseshoe Concept Plan
177
B.1 Plants
Appendix B: Biotic Resources
fasciculatum), dominate the Chaparral plant community. Associated
species include various salvias (Salvia mellifera, Salvia apiana),
lemonade berry (Rhus integrifolia), and sugar bush (Rhus ovata) (see
Figure B.1-4, Existing Vegetation Types, Altadena Crest Trail).
Chaparral and Coastal Sage Scrub are two plant communities that are
rapidly disappearing from the Southern California landscape. The San
Gabriel Mountains and Angeles National Forest are the few remaining
areas where these plant communities can still thrive. Their health
means the success of many sensitive wildlife species, including the
California gnatcatcher and Behr’s metalmark (see Table B.2-1, Wildlife
Design Species Matrix) that rely on these communities.
Mule Fat Scrub, dominated by Mule fat, (Baccharis salicifolia), is similar
to Chaparral and Coastal Sage Scrub plant communities; however, it is
located further down slope along perennial and intermittent stream
channels making it a more water-tolerant plant community (see
Figure B.1-6, Plant Communities Profile). Mule Fat Scrub habitat needs
seasonal flooding for its survival, hence the associated species, Arroyo
willow (Salix lasiolepis), Mexican elderberry (Sambucus mexicana), and
various sedges (Carex pansa, Carex spissa) (Sawyer, Keeler-Wolf 1995,
City of Pasadena 2003, Sapphos Environmental 2006, Keeley 2002).
Southern Sycamore–Alder Riparian Woodlands, Southern Willow
Scrub
At the base of the San Gabriel Mountains and throughout the valley
riparian courses are dotted with water-loving Southern Sycamore–
Alder Riparian Woodlands and Southern Willow Scrub. While these
two plant communities house many of the same species, Southern
Willow Scrub can be found at higher elevations than Southern
Sycamore-Alder Riparian Woodlands because it requires more water.
Southern Willow Scrub requires repeated flooding and is comprised of
dense, broad-leaved, winter-deciduous riparian vegetation. This plant
community is dominated by various willow species such as Arroyo
willow (Salix lasiolepis), black willow (Salix gooddingii), red willow (Salix
laevigata), shining willow (Salix lucida), and narrow leaved willow
178
(Salix exigua). Southern Willow Scrub lives in loose, sandy, or fine
alluvium typically found in streams or along the banks. Stands of the
community are dense, preventing a significant understory; however,
in more open scrub habitats, forbs and grasses may grow. Like Mule
Fat Scrub, Southern Willow Scrub is composed of individual species
that may occur in wetlands, such as Western ragweed (Ambrosia
psilostachya) and Mugwort (Artemisia douglasiana). These species
have the ability to grow and reproduce in soils intermittently or
continuously saturated with water (Sawyer, Keeler-Wolf 1995, City of
Pasadena 2003, Sapphos Environmental 2006, Keeley 2002).
Southern Sycamore-Alder Riparian Woodlands are dominated by
white alder (Alnus rhombifolia) and Western sycamore (Platanus
racemosa). This is a winter deciduous woodland with an average
canopy of 115 feet. Trees are mostly scattered in thickets of hardleaved and deciduous species and are present at elevations within
the Altadena Crest Trail (see Figure B.1-6, Plant Communities Profile)
(Sapphos Environmental 2006). Riparian plant communities, such as
Southern Sycamore-Alder Riparian Woodland and Southern Willow
Scrub are particularly important in Los Angeles due to their role in
maintaining the health of the region’s waterways and aquatic species.
Riparian plants help clean natural water systems and provide nesting
environments for wildlife. Without these plant communities, the
region’s natural hydrologic cycle will never be restored.
Riversidean Alluvial Fan Sage Scrub
Only remnants of the Riversidean Alluvial Fan Sage Scrub, which once
dominated the alluvial fan terraces of the valley, remain. This is a dry
or xeric plant community that can tolerate temporary inundation
and uses coarse soils to store and release moisture slowly. This plant
community, found in old and young alluvial fan terraces, developed
as a result of water and sediment deposition that came down the
mountains during rain events. Due to development and flood control
measures, Riversidean Alluvial Fan Sage Scrub is considered sensitive
habitat by the State of California. The City of Pasadena, in a master
plan for the Arroyo Seco, noted that without the presence of Devil’s
Restore, preserve, and reconnect habitat
OBJECTIVES •• Preserve
sensitive native species
Bigcone SpruceCanyon Oak Forest
Coast Live Oak
PLANT COMMUNITIES
Coastal Sage
Scrub
Chamise Chaparral
Mule Fat
Scrub
Riversidean
Alluvial Fan
Sage Scrub
Ruderal
Nonnative
Grassland
Southern
Sycamore-Alder
Riparian
Woodland
Southern
Willow
Scrub
Ruderal Vegetation
Just as development has led to
the loss of Riversidean Alluvial
Fan Sage Scrub habitat, it has
CALIFORNIA NATIVE PLANT SOCIETY
INDICATOR SPECIES
also contributed to the ruderal
vegetation so prevalent
throughout the watershed
today. Ruderal vegetation
FEDERALLY
STATE
POTENTIAL TO EXIST
describes non-native plant
LISTED
LISTED
WITHIN SITE
species or weeds and includes
areas impacted by agriculture,
construction, and other
development activities. Fire
is another cause of ruderal
DESIGN SPECIES
vegetation, particularly in
Nevin’s barberry
Braunton’s milk-vetch
Canyon Live Oak
Chaparral and Coastal Sage
Berberis nevinii
Astragalus brauntonii
Quercus chyrsolepis
Scrub habitats. Non-native
grass and forb species are able
Figure B.1-7, Plant Design Species Selection Process
to out-compete non-sprouting
native shrubs when fire
Selection of Design Plant Species
occurs more frequently than
Figure B.1-7, Plant Design Species Selection Process demonstrates the
twice per decade (see Appendix D, Supplemental Research). Ruderal
process of selecting design plant species for the Emerald Horseshoe
vegetation provides the lowest habitat value for wildlife and the
project area. The process began by examining the objectives as they
least opportunity for biodiversity (Sawyer, Keeler-Wolf 1995, City of
relate to habitat. Species were considered based on their relationship
Pasadena 2003, Sapphos Environmental 2006, Keeley 2002).
to the nine project area plant communities, their classification by the
Emerald Horseshoe Concept Plan
Appendix B: Biotic Resources
Gate Dam, Riversidean Alluvial
Fan Sage Scrub would have
spread across most of the
area (see Figure B.1-3, Existing
Vegetation Types, Arroyo Seco )
(Sawyer, Keeler-Wolf 1995, City
of Pasadena 2003, Sapphos
Environmental 2006, Keeley
2002).
179
B.1 Plants
Table B.1-1, Plant Selection Matrix
KEY:
Design Species
Additional Native Species
FE: Endangered under the federal Endangered Species Act; SE: Endangered by the State of California; CNPS 1B and 4.2: Rare, threatened, or endangered by the
California Native Plant Society
Braunton’s milk-vetch
Astragalus brauntonii
Coast
Live
Oak
Coastal
Sage
Scrub
Chamise
Chaparral
Mule
Fat
Scrub
Riversidean
Alluvial Fan
Sage Scrub
Ruderal
Nonnative
Grassland
Southern
SycamoreAlder
Riparian
Woodland
Southern
Willow
Scrub
Special
Status
Potential
to exist on
site
FE, CNPS
1B
Moderate
to come
Canyon Live Oak
Quercus chrysolepis
Davidson’s bush mallow
Malacothamnus
davidsonii
Nevin’s barberry
Berberis nevinii
Correct Photo
Moderate
CNPS 1B
Moderate
FE, SE,
CNPS 1B
Moderate
CNPS 1B
Moderate
CNPS 1B
Moderate
CNPS 1B
Moderate
Robinson’s pepper-grass
Lepidium virginicum
var. robinsonii
CNPS 1B
Moderate
San Gabriel bedstraw
Galium grande
CNPS 1B
Moderate
CNPS 1B
Low
Spotted Humboldt’s lily
Lilium humboldtii var.
ocellatum
CNPS 4.2
Low
Southern California
Black Walnut
Juglans californica
CNPS 4.2
Moderate
Many-stemmed dudleya
Dudleya multicaulis
Mesa horkelia
Horkelia cuneata ssp.
Puberula
Plummer’s mariposa lily
Calochortus plummerae
Slender mariposa lily
Calochortus clavatus
var. gracilis
180
Bigcone
SpruceCanyon
Oak
Forest
Data from: Sawyer and Keeler-Wolf 1995, Sapphos Environmental 2005
Appendix B: Biotic Resources
Plant Species
Canyon Live Oak, Quercus
chrysolepis
Canyon live oak is an indicator
species in the Bigcone Spruce
Canyon Oak Forest plant
community. The Canyon live oak
is found from the Coast Ranges
and Cascade Range of Oregon
south through the Sierra Nevada
in California and to Baja California,
Mexico. The Canyon live oak is an
evergreen species that varies in
size and form depending on its
location. In shady canyons, the
species may reach 100 feet in
height, while on exposed slopes
Figure B.1-9, Canyon live oak
it stays smaller and appears
shrubby. Forests dominated by Canyon live oaks provide habitat
and food for a large variety of wildlife, including the Cooper’s hawk
(Accipiter cooperii). The Canyon live oak is a particularly important
species within the Emerald Horseshoe project area due to its high
ecological and morphological diversity. The species’ occurrence
throughout a wide range of elevations, topography, and vegetation
types indicates its ecological variability (Thornburgh 2008).
Appendix B: Biotic Resources
disturbance environments, such as fire, which interrupts the seed
dormancy. The biggest threat to Braunton’s milk-vetch is the loss of
native habitat. Disturbance caused by housing construction in the
foothills and trampling by hikers, off-road vehicles, and equestrians
contributes to this habitat loss. Changes in the natural fire cycle,
and habitat fragmentation and degradation by invasive weeds also
create conditions unsuitable for Braunton’s milk-vetch to thrive
(Center for Plan Conservation 2008). The Southern California National
Forests are currently generating models that depict suitable habitat
for the species. These models will then be used to manage existing
populations (CNDDB 2000).
Source: Jennifer Mitamura 2008
Source: Michael W. Tuna 2006
California Native Plant Society, and their listing as indicator species.
Federally and state-listed species were also selected based on their
potential to exist within the project area. Table B.1-1, Plant Selection
Matrix illustrates where the four design species fall within each of the
nine plant communities. It also shows each species’ potential to exist
in the site area and what status (federal, state, or California Native Plant
Society) each species holds. This matrix was utilized to determine
which species would be focused on in the Emerald Horseshoe design.
Design Species
Braunton’s milk-vetch, Astragalus brauntonii
Braunton’s milk-vetch is listed as endangered under the federal
Endangered Species Act and as rare, threatened, or endangered by
the California Native Plant Society. There are currently 16 existing
locations of Braunton’s milk-vetch within Simi Hills of Ventura and
Los Angeles counties, the Santa Monica Mountains, the San Gabriel
Mountains, and the Santa Ana Mountains in Orange County. The
species generally occurs below
2,100 feet in elevation on
south-, west-, and east-facing
slopes, in open chaparral.
Braunton’s milk-vetch can
also be found in disturbed
locations such as burn areas,
along fire roads, fuel breaks,
and where some clearing has
occurred and competition
from non-native species is
low. The species is a perennial
Figure B.1-8, Braunton’s milk-vetch
member of the pea family. It
blooms lilac flowers from March
to July and typically appears after a chaparral fire along with other
native perennial forbs (Munz 1974). The plant typically lasts several
years before it is crowded out by other vegetation. Its seeds survive
in the soil bank for several years and have a seed coat typical of many
chaparral plants. This explains the species germination in post-
Emerald Horseshoe Concept Plan
181
Nevin’s barberry, Berberis
nevinii
Nevin’s barberry is listed
as endangered under
the federal Endangered
Species Act and the State
of California, and rare,
threatened, or endangered
by the California Native Plant
Society. Nevin’s barberry
Figure B.1-10, Nevin’s barberry
is currently scattered
throughout Southern California from Los Angeles County, east to
Riverside and San Bernardino counties. The species grows in sandy or
gravelly soils on steep north-facing slopes or on low gradient southfacing washes within Alluvial Scrub, Coastal Sage Scrub, or Riparian
Scrub or Woodland habitats.
Source: Stan Shebs 2007
Appendix B: Biotic Resources
B.1 Plants
Nevin’s barberry is a large shrub with blue-green, spiny pinnate leaves.
Red edible berries and yellow flowers bloom March through April.
The species status as a federally endangered species is largely due
to habitat loss from agriculture, urban development, flood control,
and stream channelization (Mistretta and Brown 1989). Cultivation of
Nevin’s barberry on private property constitutes the majority of known
occurrences of the species as it has proven to be tolerant of various
soils and cultivation practices. The United States Forest Service staff in
Angeles National Forest currently monitors the species; however, more
surveys to locate suitable habitat throughout the project area should
be conducted (CNDDB 2000).
182
B.2 Wildlife
Wildlife and their associated habitat play a vital role in the biological
and ecological processes that are essential to our human lives. These
key processes depend on numerous interactions between microorganisms, plants, and animals. Wildlife species facilitate the processes
of pollination, seed dispersal, germination, soil generation, nutrient
cycling, predation, habitat maintenance, waste breakdown, and pest
control.
Many unique animals, which help to conduct these processes on a
local scale, are found in the Los Angeles Region. Sadly, Los Angelenos
remain largely unaware of these species. Selecting key wildlife species
for which to design would help to foster the education and protection
of these native animals and their habitat.
Selection of Design Wildlife Species
Design wildlife species have been selected to ensure the preservation
of those animals that are still present, despite their low numbers. Their
success is a direct reflection of the ecological health of the entire
region. Utilizing research garnered from the Green Visions Plan, and
• Sensitive—Is the species sensitive to human disturbance or is it human-tolerant?
• Connectivity—Is the species sensitive to the distance between habitat patches?
• Biodiversity—Is there evidence that the species is an indicator of biodiversity in its or another taxonomic group?
• Rare—Is the species rare in the study area?
• Keystone—Is the species disproportionately important to its ecosystem relative to its abundance?
• Umbrella—Will protection of the species result in the protection of other species?
• Fragmentation—Is the species sensitive to the size of habitat fragments?
• Habitat quality—Is the species sensitive to degradation of habitat quality?
• Knowledge—Is there sufficient scientific knowledge about the species to use it effectively?
Appendix B: Biotic Resources
Source: Flickr 2008
Figure B.2-1, Bobcat
The process for choosing wildlife began by looking at the project
objectives. Next, the Green Visions Plan’s criterion for selecting
design wildlife species was utilized. The Green Visions Plan offers an
assessment of wildlife species, which includes the following nine
categories (Martino et al. 2005):
Appendix A: Biotic Resources
the Fire and Resource Assessment Program, existing suitable habitat
within the project area was determined for design wildlife species.
As with many of the plant communities that once existed in the Los
Angeles region, various species of wildlife that once thrived in the
area such as grizzly bears (Ursus arctos horribilis) have been extirpated.
Maintaining the health and wellbeing of existing wildlife in the project
area is crucial to the success of the entire watershed.
After consulting the Green Visions Plan, the project area’s nine plant
communities and trophic structure were examined to determine
which wildlife species to focus on (Figure B.2-2, Wildlife Design Species
Selection Process).
Emerald Horseshoe Concept Plan
183
B.2 Wildlife
Appendix A:
B: Biotic Resources
Restore, preserve, and reconnect habitat
OBJECTIVES •• Preserve
sensitive native species
PLANT
COMMUNITIES
GREEN VISIONS
PLAN CRITERIA FOR
DESIGN SPECIES
Bigcone Spruce-Canyon Oak Forest
Coast Live Oak • Coastal Sage Scrub
Chamise Chaparral • Mule Fat Scrub
Riversidean Alluvial Fan Sage Scrub
Ruderal Nonnative Grassland
Southern Sycamore-Alder Riparian Woodland
Southern Willow Scurb
Sensitive • Connectivity • Biodiversity
Rare • Keystone • Umbrella • Fragment
Habitat Quality • Knowledge
TROPHIC
STRUCTURE
Primary Consumers
Secondary Consumers
Tertiary Consumers
DESIGN SPECIES
California Gnatcatcher
Polioptila californica
Cooper's Hawk
Accipiter cooperii
Unarmored Threespine Stickleback
Gasterosteus aculeatus williamsoni
Figure B.2-2, Wildlife Design Species Selection Process
184
Mountain Lion
Puma concolor
Western Spadefoot Toad
Spea hammondii
Behr's Metalmark
Apodemia virgulti
Southwestern Pond Turtle
Clemmys marmorata pallida
Appendix B: Biotic Resources
Tertiary Consumers
Secondary Consumers
Primary Consumers
Producers
Organic Matter
Adapted from: Steiner 2000
The wildlife matrix illustrates
how each of the seven design
species fit into the selection
criteria (see Table B.2-1,
Wildlife Design Species Matrix).
Once again, the relationship
of these wildlife species to
the nine project area plant
communities was key. As the
Emerald Horseshoe project
seeks to restore, preserve,
and reconnect habitat
the mutually beneficial
association of vegetation and
wildlife could not be ignored.
Appendix A: Biotic Resources
The trophic structure reflects
the relationship between
the plant and animal species
found within a patch of
habitat. This cyclical feeding
interaction includes predatorprey, parasite-host, and plantherbivore relationships and
demonstrates the potential
for food competition. The
trophic structure played an
integral role in determining
the design wildlife species
for the Emerald Horseshoe
project area (Figure B.2-3,
Trophic Structure).
Adapted
from:
Steiner 2000
Figure
B.2-3,
Trophic
Structure
Emerald Horseshoe Concept Plan
185
B.2 Wildlife
Table B.2-1, Wildlife Design Species Matrix
Species/Criteria
KEY:
Design Species
Additional Native Species
Habitat
Sensitive Connectivity Biodiversity Rare Keystone Umbrella Fragmentation Quality
Knowledge
Associated Plant
Communities
Burrowing Owl
Athene cunicularia
California Gnatcatcher
Polioptila californica
Sage Scrub, Native
Alluvial Fan Sage
Scrub, Mixed
Chaparral
California Quail
Callipepla californica
Riparian Woodlands,
Chaparral, Sage Scrub
Cooper’s Hawk
Accipiter cooperii
Deciduous, Mixed and
Conifer Forests, Oak
Woodlands
Loggerhead Shrike
Lanius ludovicianus
Chaparral, Sage Scrub,
Conifer Forest,
Grassland
Rufous-crowned
Sparrow
Aimophila ruficeps
Chaparral, Sage Scrub
Sea Sparrow
Amphispiza belli
Chaparral, Sage Scrub
Western Meadowlark
Strunella neglecta
Dune, Grassland
White-tailed kite
Elanus leucurus
Grassland, Wetlands,
Riparian Woodlands
Yellow-breasted Chat
Icteria virens
Riparian Hardwood
Forest
Data from: Cornell Lab of Orinthology 2003, Illinois Natural History Survey 2008, Martino et al 2005, Mock 2004
186
Dune, Grassland
Data from: Cornell Lab of Ornithology 2003, Illinois Natural History Survey 2008, Martino et al. 2005, Mock 2004
Appendix A:
B: Biotic Resources
Birds
Species/ Criteria
KEY:
Design Species
Additional Native Species
Habitat
Sensitive Connectivity Biodiversity Rare Keystone Umbrella Fragmentation Quality
Species of Consideration
Knowledge
Appendix A: Biotic Resources
Table B.2-1, Wildlife Design Species Matrix (continued)
Associated Plant
Communities
Chaparral/ Sage Scrub,
Conifer Forest,
Riparian Hardwood
Forest
California Meadow
Vole
Mycrtous californicus
Grassland
Coyote
Canis latrans
Chaparral/ Sage Scrub,
Conifer Forest, Dune,
Grassland, Riparian
Grey Fox
Urocyon
cinereoargenteus
Chaparral/ Sage Scrub,
Conifer Forest,
Grassland
Long-tailed Weasel
Mustela frenata
Chaparral/ Sage Scrub,
Conifer Forest, Dune,
Riparian Hardwood
Forest
Mountain Lion
Puma concolor
Chaparral/ Sage Scrub,
Conifer Forest, Riparian
Hardwood Forest
San Diego Black-Tailed
Jackrabbit
Lepus californica
Chaparral, Open Forest,
Grassland
Data from: Martino et al. 2005
Bobcat
Lynx rufus
Appendix B: Biotic Resources
Mammals
Data from: Cornell Lab of Orinthology 2003, Illinois Natural History Survey 2008, Martino et al 2005, Mock 2004
Emerald Horseshoe Concept Plan
187
B.2 Wildlife
Table B.2-1, Wildlife Design Species Matrix (continued)
Species/ Criteria
KEY:
Design Species
Additional Native Species
Habitat
Associated Plant
Sensitive Connectivity Biodiversity Rare Keystone Umbrella Fragmentation Quality Knowledge Communities
Appendix A:
B: Biotic Resources
Fish
Unarmored Threespine
Stickleback
Gasterosteus aculeatus
williamsoni
Arroyo Chub
Gila orcutti
Freshwater Streams
Freshwater Streams
Amphibians
Coast Range Newt
Taricha torosa
Riparian Hardwood Forest,
Chapparal, Sage Scrub,
Conifer Forest, Grassland
Western Spadefoot Toad
Spea hammondii
Chaparral, Sage Scrub,
Conifer Forest,
Grassland
Coast Horned Lizard
Phrynosoma coronatum
Native Alluvial Fan Sage
Scrub, Chaparral,
Sage Scrub
Southwestern Pond
Turtle
Clemmys marmorata
pallida
Riparian Hardwood Forest,
Ponds, Marshes, Reservoirs,
Shallow Wetlands
Invertebrates
Behr’s Metalmark
Apodemia virgulti
188
Data from: Cornell Lab of Orinthology 2003, Illinois Natural History Survey 2008, Martino et al 2005, Mock 2004
Chaparral, Sage Scrub
Data from: Martino et al. 2005
Reptiles
Appendix B: Biotic Resources
Source:: Friends of Chollas Creek
Appendix A: Biotic Resources
California
Gnatcatcher,
Polioptila californica
The California
gnatcatcher is a state
and federally listed
endangered species
(see Figure B.2-4,
California Gnatcatcher).
Relatively open sage
scrub, native alluvial
Figure B.2-4, California Gnatcatcher
fan sage scrub, and
chaparral support this species. The gnatcatcher breeds from February
to mid-June and lays 75 percent of its eggs between April and
May. For nest building, the gnatcatcher prefers the center of native
shrubs such as California sagebrush (Artemisia californica), California
buckwheat (Eriogonum fasciculatum), and Laurel sumac (Malosma
laurina). Nest success is more likely in these interior areas as predation
by cowbirds or feral or domestic cats is one of the main threats to
the species. Habitat loss, degradation, and fragmentation are serious
threats to the bird. The gnatcatcher was chosen as a design species
for the Emerald Horseshoe Concept Plan due to its endangered
status and its reliance on Coastal Sage Scrub. By choosing a species
that requires a rapidly disappearing plant community for its survival,
management efforts must preserve both the bird and its habitat type,
fulfilling multiple project objectives. Management recommendations
for the species include off-road monitoring in Coastal Sage Scrub
habitats in coastal California (Atwood and Bontrager 2001, Grishaver
et al. 1998, Mock 2004) (Figure B.2-5, California Gnatcatcher Existing
Habitat).
Existing Habitat
0
4
8 Miles
N
Emerald Horseshoe
Figure B.2-5, California Gnatcatcher Existing Habitat
Emerald Horseshoe Concept Plan
189
190
Cooper’s Hawk,
Accipiter cooperii
The Cooper’s hawk lives
in deciduous, mixed,
and conifer forests, and
oak woodlands (see
Figure B.2-6, Cooper’s
Hawk). Within the
project area, the hawk
is present throughout
the upper watershed
Figure B.2-6, Cooper’s Hawk
and sporadically down
the Arroyo Seco.
The Cooper’s hawk depends on good habitat quality for its survival.
During breeding season, between March and August with its peak in
May through July, the species uses an open bowl of sticks in the main
crotch of a tree to build its nest. While the Cooper’s hawk is becoming
increasingly more common in suburban and urban areas, pesticides,
degraded habitat, and collision with windows represent several threats
to the species. Human activities also have an impact on raptor nests by
physically harming or killing eggs, or altering habits. The Cooper’s hawk,
as a raptor species, has an important role in the Emerald Horseshoe
Concept Plan as it preys on the cowbirds that threaten the California
gnatcatcher. Therefore, the success of the Cooper’s hawk may increase
the potential success of the California gnatcatcher. Management
recommendations for the success of the Cooper’s hawk include creating
a spatial and temporal buffer zone for nesting raptors. Median buffer
zones should be 1,722 feet (525 meters) wide and should last from the
arrival of the adult birds to the nesting area through the first few weeks
of nesting development (Cornell Lab of Ornithology 2003, Haiman
2006) (Figure B.2-7, Cooper’s Hawk Existing Habitat).
Source: Sean Sime 2008
Appendix A:
B: Biotic Resources
B.2 Wildlife
Existing Habitat
0
Emerald Horseshoe
Figure B.2-7, Cooper’s Hawk Existing Habitat
4
8 Miles
N
Appendix B: Biotic Resources
Source: U.S. Fish and Wildlife Service 2008
Appendix A: Biotic Resources
Bobcat, Felis rufus
The bobcat lives in
chaparral, sage, conifer
forest, and riparian
hardwood forest (see
Figure B.2-8 Bobcat).
This species breeds
from February through
March and builds its
dens in the rock piles
or broken rocky ledges
Figure B.2-8, Bobcat
of the San Gabriel
Mountains. While the
bobcat is not commonly preyed upon, kittens may be taken by foxes,
coyotes, mountain lions, or owls. The bobcat, along with the Cooper’s
hawk, is one of the Emerald Horseshoe’s top predator design species,
an indication of the cat’s significant role within the trophic structure.
Threats to the species include habitat fragmentation and poor habitat
quality, which explains its concentration in the upper watershed of
Angeles National Forest. Bobcats have an important role in the Emerald
Horseshoe Concept Plan as their habitat sensitivity, particularly in adult
females, makes them an important species to monitor. Management
recommendations for the bobcat include maintaining a mosaic of cover
types in riparian areas and on preferred areas such as cliffs and rock
outcroppings (Martino et al. 2005, United States Forest Service 2008)
(Figure B.2-9, Bobcat Existing Habitat).
Existing Habitat
0
4
8 Miles
N
Emerald Horseshoe
Figure B.2-9, Bobcat Existing Habitat
Emerald Horseshoe Concept Plan
191
Unarmored Threespine
Stickleback,
Gasterosteus aculeatus
williamsoni
There is a lack of existing
suitable habitat for the
unarmored threespine
stickleback within the
Emerald Horseshoe
project area (Figure B.210, Unarmored Threespine
Stickleback) The
Figure B.2-10, Unarmored Threespine Stickleback
stickleback is a state and
federally listed endangered species extirpated from the Los Angeles
River watershed in the 1940s as a result of habitat contamination and
loss (Figure B.2-11, Unarmored Threespine Stickleback Existing Habitat).
The only existing suitable habitat in the region for the stickleback is a
small segment of freshwater in the upper San Gabriel River, outside of
the Emerald Horseshoe project area. The stickleback was chosen for the
Emerald Horseshoe project due to its standing as an indicator of good
hydrologic function, water quality, and its extremely sensitive nature
(Martino et al. 2005).
Source: Aquatic Resource Specialists 2008
Appendix A:
B: Biotic Resources
B.2 Wildlife
The unarmed threespine stickleback breeds from April through July.
The fish builds its nest from aquatic plants and algae in quiet, shallow
water, weedy pools, and clear slow-moving streams. The species is a
good indicator of water quality due to its need for clear slow-moving
water, not a typical feature of existing, altered waterways of the Los
Angeles region. In addition to poor water quality, threats to the species
include exotic or introduced animal species that use the stickleback’s
habitat. Management recommendations include monitoring of the
unarmored threespine stickleback, and removal of exotic animal
species and plant species (USGS 2001).
192
No Existing Habitat
Emerald Horseshoe
0
4
8 Miles
Figure B.2-11, Unarmored Threespine Stickleback Existing Habitat
N
Appendix B: Biotic Resources
Source: Sean Sime 2008
Appendix A: Biotic Resources
Western Spadefoot
Toad, Spea
hammondii
The Western
spadefoot toad
lives in Coastal Sage
Scrub, Chaparral,
grasslands, and
grasslands with
vernal pools (see
Figure B.2-12,
Figure B.2-12, Western Spadefoot Toad
Western Spadefoot
Toad). The species breeds during the winter and spring months, from
January through May in these vernal pools, or other temporarily
wet areas. This species has only sporadic suitable habitat in the
Emerald Horseshoe project area mostly due to habitat loss by urban
development and conversion of native habitats to agricultural lands.
The toad was chosen for the Emerald Horseshoe project as the success
of the species would indicate that lands were stable and undisturbed
enough to support it (Martino et al. 2005, Toure 2003) (Figure B.2-13,
Western Spadefoot Toad Existing Habitat).
Existing Habitat
0
4
8 Miles
N
Emerald Horseshoe
Figure B.2-13, Western Spadefoot Toad Existing Habitat
Emerald Horseshoe Concept Plan
193
Southwestern Pond
Turtle, Clemmys
marmorata pallida
The Southwestern pond
turtle was chosen as a
design species for the
Emerald Horseshoe
project because it, like
so many other design
species, lacks substantial
Figure B.2-14, Southwestern Pond Turtle
habitat in the project
area (see Figure B.2-14,
Southwestern Pond Turtle). The pond turtle relies on riparian hardwood
forest, ponds, marshes, shallow wetlands and reservoirs, all of which
have been significantly altered in the urban environment. The pond
turtle has a linear, riparian home range and may act as an umbrella
for other species requiring good habitat quality in close proximity to
streams. The pond turtle, from May through July, oviposits in sunny
upland habitats between 100 and 1,400 feet from freshwater. Focusing
on the success of a riparian species, such as the Southwestern pond
turtle, would ensure that the project, once implemented, would
continue to maintain the health, size, and connectedness of its
waterways. Due to the pond turtle’s historical distribution in the Arroyo
Seco subwatershed, habitat restoration opportunities may exist in
upper watershed tributaries such as in Fern Canyon or Millard Canyon
(Martino et al. 2005, United States Army Corp of Engineers 2005)
(Figure B.2-15, Southwestern Pond Turtle Existing Habitat).
Source: California Turtle and Tortoise Club
Appendix A:
B: Biotic Resources
B.2 Wildlife
Existing Habitat
0
4
8 Miles
Emerald Horseshoe
Figure B.2-15, Southwestern Pond Turtle Existing Habitat
194
N
Source: Flickr 2008
Appendix B: Biotic Resources
Appendix A: Biotic Resources
Behr’s Metalmark,
Apodemia virgulti
The Behr’s metalmark,
a multi-colored
butterfly, finds
its home in the
Chaparral and Sage
Scrub of the San
Gabriel Mountains
(see Figure B.2-16,
Behr’s Metalmark). The
Figure B.2-16, Behr’s Metalmark
butterfly feeds on the
nectar in California
buckwheat (Eriogonum fasciculatum) and is in decline due to the loss of
its host plant to invasive weeds and urbanization. The butterfly breeds
each year from March through September. It lays its eggs in groups
of two to four on the lower leaves of its host plant. Behr’s metalmark
was chosen as a design species due to its reliance on an important
Coastal Sage Scrub plant, California buckwheat, and because of its
place as a primary consumer within the trophic structure. Management
recommendations for the species include habitat restoration and
cultivation of California buckwheat (Martino et al. 2005) (Figure B.2-17,
Behr’s Metalmark Existing Habitat).
Existing Habitat
0
4
8 Miles
N
Emerald Horseshoe
Figure B.2-17, Behr’s Metalmark Existing Habitat
Emerald Horseshoe Concept Plan
195
Species of Consideration
The mountain lion is a special species of consideration for the Emerald
Horseshoe project. While this species is prevalent in parts of the
project area, it was not chosen as a design species due to its potentially
dangerous interactions with people. In an effort to mitigate contact and
conflict areas, the mountain lion’s particular needs must be addressed.
The species is sensitive to habitat disturbance and fragmentation and
requires large swathes of land for adequate range. For advantageous
hunting, the lion uses shrub cover and rock outcroppings. Human
development provides very low potential for suitable habitat. Some
mountain lions, however, are adaptable to the urban environment.
Emerald Horseshoe trails and recreation areas would avoid infringing
on the mountain lion’s habitat and would in fact designate certain
areas for no trail planning, leaving the mountain lion its fair share of
the land. Finally, caution and educational signs would be located at
access points along the Altadena Crest Trail to further alert people
to the danger the mountain lion poses in these more remote areas
(California Polytechnic University, Pomona 2006) (see Mountain Lion
Existing Habitat).
Source: Encyclopedia Britannica Online 2007
Appendix A:
B: Biotic Resources
B.2 Wildlife
Mountain Lion
196
Existing Habitat
Emerald Horseshoe
Mountain Lion Existing Habitat
0
4
8 Miles
N