Download Appendix F. Habitat Assessment for Narrow

Appendix F.
Habitat Assessment for Narrow Endemic Plants
Report for the Liberty XXIII Renewable Energy
Power Plant Project, City of Banning, Riverside
County, California
Appendix F– Liberty XXIII Renewable Energy Power Plant Fall 2007 Vegetation AssessmentXeric Specialties Consulting - Botanical Surveys
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HABITAT ASSESSMENT FOR NARROW ENDEMIC PLANTS REPORT FOR THE
LIBERTY XXIII RENEWABLE ENERGY POWER PLANT PROJECT
CITY OF BANNING, RIVERSIDE COUNTY, CALIFORNIA
Introduction
Aspen Environmental Group contracted with Xeric Specialties Consulting to perform a seasonally-independent noncomprehensive botanical survey for the City of Banning to determine extant and potential plant/vegetation resources at the
proposed site for the Liberty XXIII Renewable Energy Power Plant project in the southeast Banning area. The field
survey was performed by plant ecologist Dave Silverman and wildlife biologist Cindy Hopkins on 18 September 2007 and
reverified in March 2008. The proposed site boundary, as surveyed, was approximately 45.2 acres. This is a distinctive
parcel, and we had little need for geo-referenced benchmarks during the survey. We included adjacent vegetation
resources in the assessment. Conditions for assessment of the site’s flora were poor seasonally and very poor for rainfall
conditions for 2006-2007. The site is located within an arid ecosystem type and the majority of extant herbaceous plant
species would have been undetectable from our survey timing. The spring (April-May) of 2005 represents the last time a
viable botanical survey could have been performed.
All perennial species of plants observed were identified. A small subset of the potential annual plant species were present
as living or recently senesced individuals, and were all identified to taxon. Most skeletons from past annual plants were
also identified to species or at least to the genus level, though available remnant annual plant skeletons were highly
reduced from the past two drought years.
Site Description
The proposed project site is located at the NW base of Mt. San Jacinto in Riverside Co, CA, where Smith Creek defines
the boundary between the north-facing foothills and the SE-trending aspect of the Banning Bench and associated alluvial
fan upon which most of the City of Banning exists. The site is approximately 3 km east of the confluence of Smith Creek
and the San Gorgonio River. Average elevation at the site is approximately 2080’. Most aspects within the site are south
to east trending. The site is characterized by two pre-existing natural landforms. The southwest portion of the site, and
southeast to east edges of the site, were previously associated with the active primary channel and associated alluvial
terraces of Smith Creek. The major, more northerly portion of the site is previously associated with the broad, south to
east-facing, braided alluvial fan landform of the East San Gorgonio Pass region.
Currently, the south half of the water treatment facility and the abandoned sand-gravel operation, now an open pit, are
located where the northern alluvial terrace of Smith Creek previously existed. The active channel is now re-directed more
eastward and the areas at the south end of the site are no longer associated with current flooding and alluvial deposition
events of Smith Creek, though there is still a significant veneer of eolian deposits onto the site from lighter Smith Creek
alluvium. Clearly, this area was a highly viable source of natural deposits of sand and gravel, thus the former operation
and current open pit are consistent with the geological nature of this part of the site. The remainder of the site is
associated with the alluvial fan landform, which remains mostly geologically intact at the northeast end of the site, but is
altered in the north portion of the sand&gravel pit, the east edge of a trash dump and along the east end of sewer pond
facilities.
Soils within the site are weakly developed, being typical of alluvial depositions that form entisols or of debris flow
depositions that form entisols or aridisols. Soil colors are dominated by the characteristic colors of the local bedrock
parent material contributors, primarily feldspars and quartz particles associated with granite and gneiss bedrock sources in
the San Jacinto and San Gorgonio ranges. Soil textures are loamy sand in their most developed upper horizons or more
frequently they are coarse decomposed parent materials in disturbed areas, active deposition zones or at depth in sub-B
horizons. To some extent, a recent history of disturbance and nutrient deposition associated with anthropogenic effects
has added a more organic and developed upper horizon to the areas associated with intact sections of the alluvial fan
landform and also to some of the naturally sterile deposits. Disturbed areas have more soil sterility related to disturbance
or removal of topsoil. This appears to be limiting the succession of woody plants in some areas, while supporting
ephemeral weedy conditions in years of high rainfall. Such rank growths, obvious from aerial photos of the site from
2005 (A near-record rainfall year), are partially fueled by above-background nutrient depositions. A more widely-spaced
distribution with smaller, and more native herbaceous annuals was likely the more historic and natural ephemeral plant
climax condition for this soil and region.
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The land use history of site has been intensive and varied, including cattle grazing, mining, dumping and the fringe effects
of the sewer ponds. The current ecological condition of the site is poor. Only parts of the Smith Creek and the northeast
end of the site resemble natural climax ecosystems. The adjacent chaparral slopes of the Mt. San Jacinto foothills were
recently burned and despite a very diverse plant assemblage currently, appear to be compromised by non-native grass type
conversions. Of the different ecosystem features associated with the site, the wash scrub associated with Smith Creek
appears to be most healthy and capable of continued renewal and recovery.
Overview of the south part of the proposed project site, as viewed from the burned chaparral hill to the east of the site, with Smith Creek to the left
and in the foreground. The site is mostly located in the upper right of the photo. There are four basic vegetation cover types associated with the site;
the wash scrub in Smith Creek, the denuded or herbaceous-ephemeral area associated with the open pit, the buckwheat scrub that fringes the pit and
the catclaw fan scrub at the right edge of the photo.
Overview of the north part of the proposed project site, as viewed from the burned chaparral hill to the east of the site, with Smith Creek in the
foreground. The site is mostly located in the upper left of the photo with the Banning airport in the upper right background. Two of the vegetation
cover types associated with the site are visible. Wash scrub is associated with Smith Creek and the associated alluvial terrace. Catclaw fan scrub is
the dominant intact vegetation type in most of the background.
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Vegetation Description
Currently, four basic vegetation cover types occur within the site boundaries (see maps below). These include wash scrub
and catclaw fan scrub vegetation communities which are mostly natural stands. A low scrub dominated by monotypic
stands of California buckwheat (Eriogonum fasciculatum) is a successional plant community associated with partially
recovered disturbed areas or as an invader-replacement of disturbed zones within the natural vegetation stands. A large
portion of the site is associated with a mostly denuded open pit, where sparse weedy herbaceous plants, mostly typical of
sand fields, form a weak cover in most years.
The former and current vegetation states of site are different. Historically, it was likely that a significant portion of the
south half of the site was a semi-desert wash scrub, similar to, but more arborescent than, the current wash scrub
associated with Smith Creek. The past species composition probably included more stands of desert willow (Chilopsis
linearis), catclaw acacia (Acacia greggii), elderberry (Sambucus mexicana), mesquite (Prosopis sp.), scattered true
willows (Salix spp.) and scattered oaks. The shrub component of this former vegetation stand was likely different in
composition as well, with perhaps rabbitbrush (Chrysothamnus spp.) present, and more California ephedra (Ephedra
californica) and four-wing saltbush (Atriplex canescens) present than currently.
The wash scrub composition is now restricted to the south and east edges of the site. Though desert willow and catclaw
acacia are still frequent in this vegetation stand, the current composition appears to more shrub-based, with increased
densities of scalebroom (Lepidospartum squamatum) and California buckwheat (Eriogonum fasciculatum). Scalebroom
was a likely common component of the historic wash scrub vegetation in this area, but is a species that increases rapidly
when wash channels are destabilized. California buckwheat was likely not strongly associated with the climax wash scrub
vegetation type, but has become a ubiquitous woody cover in the upper drainages of Smith and Montgomery Creeks.
The other major natural vegetation type that is associated with the site is the catclaw acacia fan scrub. Historically, most
of the south and east parts of the Banning area were a very homogenous scrub similar to extant sections to the east,
especially on the alluvial fan associated with the Morongo Indian Reservation. This scrub is characterized by monotypic
stands of low-stature catclaw acacia (Acacia greggii), a species normally restricted to sparse stands in desert drainages
and ravines in association with other woody species. Few areas in its broad range, that includes much of southeast
California, southern Arizona and New Mexico, and northern Mexico, does this plant occur in densities that define a
dominant vegetation cover type and rarely as an upland occurrence. Though the species is widespread and common, this
plant community in the Banning-Cabazon area represents one of the more unique vegetation types in California. This
vegetation type exists as single broad occurrence in the region, and is mostly unrecognized by published descriptions of
the state’s vegetation types. Few other woody species are associated with this vegetation type. Cacti, particularly
Cylindropuntia californica, Opuntia basilaris and O. Phaecantha are probably the most distinctive associates, and occur
as unique ecotypes in this area.
The northeast portion of the site and adjacent areas to the north and east are mostly typical of the catclaw fan scrub
vegetation type, though the history of land uses and disturbances at the site have reduced the density of Acacia, highly
altered the historic native herbaceous plant associates and opened up successions of other scrubs, primarily California
buckwheat. Cacti appear to be more numerous than expected, a frequent vegetation effect in heavily grazed sites. More
intact stands of the catclaw scrub occur close to the site, to the northeast, but those within the site are in a degraded
condition.
Currently, much of the site has a vegetation cover of California buckwheat in pure stands east of the ponds, among the
trash dump and on the fringes of the open pit. It also occurs as a disturbance follower in all other areas. Some of the
stands appear to be associated with revegetation seeding.
In denuded areas, a very sparse group of herbaceous weedy species occurs. During our visit, the most common plants in
this area were Croton californicus, Eremocarpus setigerus, and Eriogonum gracile. It appears that the denuded areas are
phasing into a semi-desert sand field ecosystem and it is expected that a botanical inventory in a year of relatively high
rainfall would yield many other herbaceous species characteristic of sandy ecosystems, both exotic and native species
with generally weedy habits.
Areas adjacent to the site are developed to the east, catclaw acacia fan scrub (both intact and disturbed) to the north and
northeast, wash scrub to the east, burned chaparral to the east, southeast and mostly to the south, with some richer forms
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of chaparral or coastal scrub types, intact, burned or altered, present in narrow niches along the mountain flanks to the
south and southwest.
Many-stemmed Dudleya (Dudleya multicaulis)
Dudleya multicaulis is a Riverside MSHCP narrow endemic species listed for this project. This plant is very well known
from extensive collections and records in a very well documented species distribution. It is known from northwest San
Diego County (Camp Pendleton-San Onofre), north, throughout Orange county, to Los Angeles County (most northerly in
the vicinity of San Dimas), east to San Bernadino (Ontario) and western Riverside County (Santa Ana River basin, east
Santa Ana and Elsinore mountains, Temescal -Temecula valleys east to Lake Mathews-Estelle Mtn-Gavilan Hills and
disjunct SE to Vail Lake). This plant occurs in a fairly faithful habitat type, typically characterized by thin soils over
clayey-rocky terrace edges in semi-arid or xeric, but coastally influenced settings. Clayey soils are very important, if not
essential, for these types (Haseanthus) of dudleyas in arid settings.
The Banning Liberty project area is generally inconsistent with the known microhabitat types, lacks the clayey soils and
many of the typical vegetation associates and is not at all consistent with the distribution of the plant, though certain plant
species present at the site, particularly Eriogonum fasciculatum, are associates at some of the known sites for Dudleya
multicaulis. Perhaps the disjunct occurrence at Vail Lake might be most similar to the Banning site. This species grows
seasonally from a subterranean corm and is very difficult to detect in dry years. Sometimes the flowering stalks are
persistent, though few of the total population will flower in dry year. It is unlikely that if this plant was present at the
Banning Liberty site that it would have been detectable by the 2007 survey and was not detected in the 2008 survey after a
period of above-average rainfall.
Several other clay-loving rare plant species, including Allium munzii, co-occur with Dudleya multicaulis on similar habitat
types, and these would have a similar chance of occurring in the Banning Liberty project area.
Yucaipa Onion (Allium marvinii)
Allium marvinii is a Riverside MSHCP narrow endemic species listed for this project, and is known from the type
collection by J.C. Marvin in April of 1921 at the ambiguously labeled locality of “Banning”. This plant remained without
detection until it was recently re-discovered northeast of Yucaipa (thus the modern name of “Yucaipa onion”). The new
collections seem to have been under taxonomic review, which is typical of a plant known from a single historic collection
of limited quality.
As with most other Allium in California, this species would require clayey soils and would seem unlikely to be found at
the Banning Liberty site, though one might look for it in a mesic north-facing drainage with localized clayey drainage
deposits in the San Jacinto flanks to the south of the site, probably on one of the slopes where oaks occurred before the
burn. Some Allium populations are briefly stimulated after burns. Most Allium are found in clay fields on low angle
slopes or at the foot of slopes. A. haematochiton will sometimes occur in isolated patches in drainages where clayey
herbaceous deposits cap bedrock.
This species grows seasonally from an underground bulb and is likely difficult to detect in dry years. It is unlikely that if
this plant was present at the Banning Liberty site that it would have been detectable by the 2007 survey, but was also not
detected during the 2008 survey after a period of rain. As with Dudleya multicaulis and other clay-loving plants, the
Liberty site appears to be poor quality habitat. The extant populations of Allium marvinii come from a different habitat
type that is more mesic, more like coastal scrub, than the Liberty site.
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