15 Chapter 2 – Mountain and Foothills Ecosystems Key Questions • What are the major ecological communities in the coastal mountains of southern California? • What is known about the status and distribution of each? • How have they changed in the last 100 to 200 years? • What rare communities exist and what are their status and trends? This chapter provides a large-scale over- view of landscape patterns and ecological communities within the assessment area. A more detailed description of the specific eco- logical processes and human land uses affecting these ecosystems is presented in chapter 3. Here we focus on the extent and distribution of each type, its current condition, and its rep- resentation on public lands across the different mountain ranges. Much of this information is based on our GIS vegetation data. How- ever, first we describe the coarse-filter analysis approach that is a major component of this assessment. The Coarse-Filter, Habitat- Based Approach According to the California Wildlife Habi- tat Relationships System (CWHR, version 5.2) and the California Flora Database (CALFLORA), the mountains and foothills of southern California are inhabited by 18 amphibian, 61 reptile, 299 bird, 104 mam- mal, and 2,900 vascular plants species (CDFG 1996; Dennis 1995). Added to that is an un- known multitude of invertebrate animals and nonvascular plants. We know very little about the specific habitat needs of the majority of these species. So how do we address all of this biological diversity in a feasible manner? Until recently, wildlife management tended to focus on the needs of a few, high- profile species (mostly game animals and endangered species). Now the potential im- portance of all members of an ecosystem has been recognized and the focus has shifted away from single-species management and towards ecosystem-based conservation (Hansen et al. 1993; Manley et al. 1995; Haufler et al. 1996). The idea that conserving broad ecological communities may be the most efficient way to maintain species diversity has gained wide- spread acceptance and is implicit in the so-called coarse-filter approach (Noss 1987). Originally developed by The Nature Con- servancy, the coarse-filter approach assumes that a representative array of ecological communities will sustain the vast majority of species, includ- ing many of the ones we know little about (fig 2.1)(Hunter et al. 1988). By relying on reten- tion of community types and providing an array of structures and compositions, we hope to “cap- ture” most of the diversity in the system. However, we know that some species, subspe- cies, and rare communities have characteristics that make them “fall through the mesh” of the coarse filter and these need special attention (i.e., a finer filter). The fine-filter approach focuses on learning the specific needs of individual spe- cies and then providing for those needs, potentially through intensive management. To understand the fashion of any life, one must know the land it is lived in and the procession of the year. — Mary Austin (1903)
Transcript
15
Chapter 2
Chapter 2 – Mountain and FoothillsEcosystems
Key Questions• What are the major ecological
communities in the coastalmountains of southern California?
• What is known about the status anddistribution of each?
• How have they changed in the last100 to 200 years?
• What rare communities exist andwhat are their status and trends?
This chapter provides a large-scale over-view of landscape patterns and ecologicalcommunities within the assessment area. Amore detailed description of the specific eco-logical processes and human land uses affectingthese ecosystems is presented in chapter 3.Here we focus on the extent and distributionof each type, its current condition, and its rep-resentation on public lands across the differentmountain ranges. Much of this informationis based on our GIS vegetation data. How-ever, first we describe the coarse-filter analysisapproach that is a major component of thisassessment.
The Coarse-Filter, Habitat-Based Approach
According to the California Wildlife Habi-tat Relationships System (CWHR, version5.2) and the California Flora Database(CALFLORA), the mountains and foothillsof southern California are inhabited by 18amphibian, 61 reptile, 299 bird, 104 mam-mal, and 2,900 vascular plants species (CDFG1996; Dennis 1995). Added to that is an un-
known multitude of invertebrate animals andnonvascular plants. We know very little aboutthe specific habitat needs of the majority ofthese species. So how do we address all of thisbiological diversity in a feasible manner?
Until recently, wildlife managementtended to focus on the needs of a few, high-profile species (mostly game animals andendangered species). Now the potential im-portance of all members of an ecosystem hasbeen recognized and the focus has shifted awayfrom single-species management and towardsecosystem-based conservation (Hansen et al.1993; Manley et al. 1995; Haufler et al. 1996).The idea that conserving broad ecologicalcommunities may be the most efficient wayto maintain species diversity has gained wide-spread acceptance and is implicit in theso-called coarse-filter approach (Noss 1987).
Originally developed by The Nature Con-servancy, the coarse-filter approach assumes thata representative array of ecological communitieswill sustain the vast majority of species, includ-ing many of the ones we know little about (fig2.1)(Hunter et al. 1988). By relying on reten-tion of community types and providing an arrayof structures and compositions, we hope to “cap-ture” most of the diversity in the system.However, we know that some species, subspe-cies, and rare communities have characteristicsthat make them “fall through the mesh” of thecoarse filter and these need special attention (i.e.,a finer filter). The fine-filter approach focuseson learning the specific needs of individual spe-cies and then providing for those needs,potentially through intensive management.
To understand the fashion of any life, one must know the land it islived in and the procession of the year.
— Mary Austin (1903)
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In this assessment we employed a com-bined coarse-filter/fine-filter approach.Fine-filter criteria were used to identify spe-cies that would receive individualconsideration (fig 2.2). The criteria primarilytarget species that are rare and vulnerable.However, we also identified species that havea heightened status due to the high public in-terest that they generate. Thus, the fine-filterlist is really divided into two distinct catego-ries: (1) species potentially at risk and (2)species of high public interest. Each speciesidentified in the fine-filter list does not neces-
Species Potentially at Risk:
• A Threatened, Endangered, or Proposed
Species (federal and state)
• A former USFWS Candidate (C1 or C2) Species
• A Forest Service, Region 5 Sensitive Species
• A California Species of Special Concern
• A Riparian Obligate Species of Concern (as
defined by California Partners in Flight)
• A species determined to have viability concerns
at a local level
Species of High Public Interest:
• A major game animal
• A species that has particular public interest (e.g.,
mountain lion)
Based on the fine-filter screening criteria,184 animals and 256 plants made the focalspecies list. These species are addressed inchapters 4 and 5, “Species at Risk,” and chap-ter 6, “Species of High Public Interest.” Allother plants and animals occurring within theassessment area will only be addressed indi-rectly, via the coarse-filter, community-levelanalysis.
The coarse-filter analysis procedure isquite simple: Current conditions are comparedto reference conditions (based on how thelandscape would look and function if peoplewere not altering it), differences between thetwo are identified, the significance of thechange is analyzed, and this information is fedinto the decision-making process. However,the application of these ideas can be quite com-plicated (Sampson et al. 1997).
The reference conditions represent ourbest attempt to describe the ecological condi-tions, including their variability over space andtime, under which native species evolved. If
sarily require specific management attention.Rather, it suggests that their status and needswarrant individual consideration before decid-ing on a course of action.
Figure 2.1. The coarse-filter approach tomaintaining biological diversity focuses onprotecting a representative array of communitiesand is based on the assumption that thesecommunities will encompass the vast majority ofspecies. The fine-filter approach focuses on savingindividual species that slip through the coarse filter.As illustrated here, the coarse filter has been usedto save a tract of Zaire’s forest, while the fine-filterapproach has been employed for the pygmychimpanzee and Congo peafowl (from Hunter et al.1988).
Figure 2.2. Fine-filter criteria used to identifyspecies that should receive individual considerationin this assessment. A species or subspecies madethe list if it met one or more of the criteria.
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Chapter 2today’s conditions are similar to the referenceconditions, we are confident that adequate habi-tat is present for most species. The greater thedeviation from the reference conditions, the morespecies may be at risk. (Sampson et al. 1997).
An inherent difficulty with this approachis that it is usually difficult to determine the“true” reference conditions and the naturalrange of variability. They must be inferredbased on our knowledge of historic habitatconditions and on our understanding of keyecological processes such as fire, succession,and flooding. Since the historic record is fre-quently sketchy and inconclusive, there areusually several plausible theories on how thehistoric landscape might have looked andfunctioned.
These problems are compounded by thefact that we will often be managing outsidethe range of conditions that native speciesencountered in the past. In some places, theecological systems are so altered that we willtypically be outside the range of conditionsthat occurred historically (e.g., in dammedriver systems or in grasslands that are nowdominated by non-native species). Social con-siderations (e.g., reducing fire hazards neartowns) and economic factors also affect ourability to remain in (or move toward) more“natural” landscapes. The farther we movefrom those conditions, the less successful wecan expect the coarse-filter approach to be(Sampson et al. 1997).
Despite these difficulties, the coarse filtercan be an effective approach for (1) retainingbiological diversity in its broadest sense, (2)retaining critical but little understood pro-cesses (such as roles played by soil microbes),and (3) sustaining species that we currentlyknow little about.
Broad-Scale LandscapeMosaics
From an airplane, land usually appears asa mosaic of patches, corridors, and matrix(Forman 1995). Woodlands, fields, and hous-ing tracts often stand out as conspicuouspatches. Rivers form equally striking corridors.
In between the patches and corridors is thesurrounding matrix — a dominant vegetationor land type, such as chaparral in the foothillsor urbanized land in the Los Angeles Basin.
Across the southern California mountainsand foothills region there are a few broad-scalelandscape mosaics that are clearly recognizableand repeatedly encountered. In the coastalfoothills the matrix is coastal scrub and chap-arral interspersed with riparian corridors, oakwoodlands, and grasslands. Above the foot-hills on often-steep lower mountain slopes, themosaic shifts to patches of mixed hardwood/conifer forest scattered between large expansesof chaparral. As you move into the uppermountain region, pine and fir forests domi-nate the landscape and are punctuated withpatches of black oak woodland, montanemeadows, and chaparral. On the desert sideof the mountain crest is another distinct land-scape, dominated by sparse pinyon forests,juniper woodlands, desert scrub, and exten-sive areas of bare rock.
Key physical factors that seem to triggerbroad-scale changes in the vegetation mosaicare elevation, distance from the coast, topog-raphy, and position on either the coastal ordesert side of the mountain crest. These fac-tors have a strong influence on precipitationamounts and temperature regimes, which inturn greatly influence the type of vegetationthat grows. Today, human land use also playsa key role in shaping these land mosaics.
Below we describe and present a map (fig.2.3) of the six large-scale vegetation mosaicsthat characterize the mountains and foothillsof southern California. In reality these mosa-ics, or “landscapes” as we refer to them here,do not have distinct boundaries but rather havebroad transition zones where different vegeta-tion assemblages intergrade. However, eachlandscape has unifying characteristics that haveimportant implications for resource manage-ment. These characteristics transcend theparticulars of which mountain range or wa-tershed the landscape may be found in. Thereare clear differences in the way each landscapetype has historically been affected and shaped
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Coastal Foothills LandscapeThe foothills range from approximately
800 to 3,000 feet in elevation on the coastalside of the mountains. In San Diego County,foothill vegetation patterns extend up to 4,000feet in some places. Although topographicallyvaried, the foothills are distinguished by manymiles of relatively gentle hilly terrain. Rollinghills, plateaus, and broad valleys are common.Chaparral is the most common vegetation, butthe foothills are also characterized by oak sa-vannas and woodlands (fig. 2.4), coastal sagescrub, and corridors of riparian hardwood for-
Figure 2.4. Looking south from Palomar Mountain, Cleveland National Forest, you see a typical foothilllandscape: oak woodlands and savannas surrounded by chaparral-covered hills. CNF FILE PHOTO
by fire, human habitation (both Native Ameri-can and early European), and other naturalprocesses. There are also differences in the wayeach landscape has been affected by recentactivities, such as the last eighty to one hun-dred years of active fire suppression and rapidhuman population growth. Because of theunique vegetation patterns in each landscapethere are also clear distinctions in the land useactivities that take place today in each of them.
est (table 2.1). Oak woodlands and savannasbecome increasingly abundant in the foothillsas you move north. This landscape is most ex-tensive in the Coast Ranges (southern SantaLucia Range, southern Los Padres region), andthe southern Peninsular Ranges (Santa AnaMountains, San Diego region).
Table 2.1. The mix of dominant vegetation typesin the foothills landscape.
Chaparral 1,407,079 55%
Grassland/
oak savanna 351,930 14%
Coastal scrub 323,250 13%
Oak woodland 268,542 11%
Development/
agriculture 112,099 4%
Other 81,890 3%
Total: 2,544,790
Vegetation Type Acres % of Foothills
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Chapter 2
Figure 2.5. The Agua Tibia Wilderness, Cleveland National Forest, is a typical lower montane landscape.Dense patches of bigcone Douglas-fir occupy steep canyons surrounded by chaparral. CNF FILE PHOTO
passes mountain slopes from approximately3,000 to 5,000 feet elevation on the coastalside of the ranges. This mosaic is character-ized by frequently steep and ruggedtopography. Chaparral dominates the hillsidesbut is interspersed with patches of forest, pri-marily in canyons and on north-facing slopes(table 2.2). Forest types are typically a coni-fer/hardwood mix. The most prevalentconifers are bigcone Douglas-fir, Coulter pine(fig 2.5), and incense-cedar, all of which oc-cur primarily in mixed stands with canyon orcoast live oak. Stands of black oak also occur,particularly at the upper elevations. Most ofthe conifer trees in this landscape are endemicto southern California and northern Baja (i.e.,Coulter pine, bigcone Douglas-fir, Tecate cy-press, Cuyamaca cypress and Sargent cypress).
Chaparral
or scrub 1,181,995 72%
Bigcone Douglas-fir/
Coulter pine/
canyon oak 272,649 17%
Oak woodland 102,979 6%
Grassland/savanna 35,159 2%
Mixed conifer 28,966 2%
Other 25,560 2%
Total: 1,647,308
Table 2.2. The mix of dominant vegetation types inthe lower montane landscape.
Vegetation Type Acres % of LowerMontane
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Figure 2.6. This view from Brush Mountain looking towards Mount Abel, Los Padres National Forest,shows several types of montane conifer forest. The open Jeffrey pine stand on Brush Mountain istypical of arid, high-country forests on the desert side of the mountains. The dense forest blanketingthe north slope of Mount Abel is typical of upper elevation mixed conifer. J.D. BITTNER
extends from approximately 5,000 to 8,500feet in elevation and is dominated by pine andfir forests (table 2.3). Stands of black oak arealso interspersed. In some areas near the lowerelevational limit, oaks are as abundant as co-nifers. As the elevation rises, dominance in theconifer overstory shifts from ponderosa pineto Jeffrey pine to white fir. Black oak declinesin abundance as elevation increases and as youmove from the coastal side to the desert sideof the mountains. Sugar pine and incense-ce-dar are secondary components in many stands.Montane meadows and chaparral are also in-terspersed. Towards the desert side of themountains, western juniper becomes a com-ponent of pine and mixed conifer stands allthe way up to 8,500 feet.
Table 2.3. The mix of dominant vegetation typesin the montane conifer landscape.
Pine or fir forest 379,304 76%
Montane chaparral 77,338 16%
Oak woodland 20,919 4%
Meadows/sagebrush 15,434 3%
Other 6,121 1%
Total: 499,116
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Chapter 2
Figure 2.7. This view to the northeast of Baldwin Lake, San Bernardino National Forest, shows pinyonpine woodlands and sagebrush flats that are characteristic of the desert-side montane landscape. LYNN
LOZIER
Desert Montane LandscapeThe desert montane landscape covers a
wide elevation range (approximately 3,000 to7,000 feet) but is often a narrow transitionzone between the mountains and the desert.Pinyon pine and juniper woodlands (fig. 2.7),scrub oak chaparral (e.g., Tucker oak), redshank chaparral, and desert scrub are the pre-dominant vegetation types (table 2.4). In thisarid landscape, plant communities generallyprovide sparse cover with a lot of bare groundin between. This mosaic is most extensive inthe lower elevations surrounding MountPinos, along the northern slopes of the SanGabriel and San Bernardino mountains, andalong the eastern slopes of the San JacintoMountains.
Vegetation Type Acres % of Desert
Montane
Table 2.4. The mix of dominant vegetation types inthe desert montane landscape.
Pinyon or
juniper woodland 346,594 36%
Semi-desert
chaparral/scrub 219,658 23%
Mixed and red shank
chaparral 130,391 14%
Buckwheat, grass,
barren 122,926 13%
Conifer or oak forest 29,904 3%
Other 27,709 3%
Total: 955,592
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Figure 2.8. Sparse stands of limber pine on theupper slopes of Mount Baden-Powell, AngelesNational Forest, are characteristic of subalpineforests near timberline. ANF FILE PHOTO
Table 2.6. The mix of dominant vegetation types inthe Monterey coast landscape.
Vegetation Type Acres % of MontereyCoast
Subalpine/Alpine LandscapeThe subalpine/alpine landscape occurs at
elevations above 8,500 feet. It covers a verysmall portion of the southern Californiamountains found only on the summit ofMount Pinos and in the highest reaches ofthe San Gabriel, San Bernardino, and SanJacinto ranges. Subalpine and alpine habitatsare most extensive on the high slopes ofMount San Gorgonio and Mount San Jacinto(fig. 2.8). The primary plant community issubalpine forest (table 2.5) that consists ofwhite fir, lodgepole pine, and limber pine.These are often relatively sparse forests char-acterized by small diameter trees. A rare andfragile alpine cushion plant community oc-curs above treeline.
occurs only along the coastal slopes of thenorthern Santa Lucia Range. It is character-ized by the southernmost occurrence of coastalredwood forest, and the southernmost con-centrations of Douglas-fir and Pacificmadrone (table 2.6). Santa Lucia fir is alsoendemic to this region. These are low-eleva-tion (sea level to 4,500 feet), mesic forestssimilar in composition and structure to for-ests along the northern California coast. Theyare distinctly different from the montane co-nifer forests found at higher elevations in therest of the assessment area.
Chaparral/scrub 35,264 35%
Redwood/
conifer forest 32,369 32%
Oak or bay forest 25,466 25%
Grassland/
savanna 6,751 7%
Other 22 <1%
Total: 99,872
Vegetation Type Acres % of
Subalpine
Table 2.5. The mix of dominant vegetation typesin the subalpine/alpine landscape.
Subalpine conifer
forest 8,229 53%
Mixed conifer–fir 2,504 16%
Montane chaparral/
scrub 2,890 19%
Alpine or barren 1,913 12%
Other 68 0%
Total: 15,604
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Chapter 2
Figure 2.9. The northern Santa Lucia Range rises dramatically above terraces along the Montereycoast. The coastal slopes of these mountains support the southernmost stands of coast redwoodforest. JEFF KWASNY
Foothill Oak WoodlandsFoothill woodlands tend to occur in two
distinct forms: as closed-canopy stands in can-yons or along streams, and as open savannasin broad valleys and rolling hills. Closed-canopy stands have a dense overstory of treeswith little space between the crowns (fig.2.10). Coast live oak is usually the dominanttree in these dense woodlands. Closed-canopycoast live oak woodlands are widely distrib-uted in the foothills and better representedon public lands than the open savanna wood-lands (table 2.8).
Savanna woodlands are characterized bywidely scattered trees with grass or coastalscrub in between (fig. 2.11). These savannascontain coast live oak but are more typifiedby blue or valley oak in the north and Engel-mann oak in the south. Savanna woodlandtypes are less extensive and more concentratedon private lands (table 2.8). Engelmann oak,valley oak, and California walnut woodlandsare considered rare communities in our assess-ment area because of limited distribution andpoor representation on public lands (Scott1990).
Major EcologicalCommunities
Many different vegetation types occuralong the southern and central California coast(table 2.7). Most of these extend into themountains and foothills to some degree. Inthis section, we describe the distribution, char-acteristics, and status of the dominantvegetation communities.
Livestock production has long been theprincipal economic activity in foothill wood-lands (Pavlik et al. 1991). Most of the privateland is consolidated in ranches that vary insize from less than a hundred to many thou-sands of acres. Grazing allotments have beenin place for many years on national forest sys-tem lands and are particularly common in oaksavanna types. On national forest system lands,60 percent of Engelmann oak woodlands and
Table 2.7. The vegetation types occurring along the southern and central California coast and associatedseries-level plant communities as described and numbered in Sawyer and Keeler-Wolf (1995). Theprimary types are crosswalked from CWHR and CALVEG calssifications.
Hardwood Forests and Woodlands
Valley–foothill woodlandsFrom sea-level to ~3,600 ft.
Oak woodlandUsually open, savanna-like woodlands with grassbelow. Or along streams or north slopes.Blue oak 230Coast live oak 241Engelmann oak 253Valley oak 312Walnut woodlandCalifornia walnut 238
Valley–foothill riparianFrom sea-level to ~4,500 ft. in canyons and flood plains.Stands usually denser than upland woodlands, but narrow.
Riparian forestBlack cottonwood 226Black willow 229California bay 234California sycamore 237Coast live oak 241Fremont cottonwood 259Mixed oak 277Red willow 299Red alder (north central coast only) 295White alder 319
Montane upland hardwoodsFrom ~3,000-8,000 ft. Occur in pure stands, but more oftenassociated with conifers. Upland live oak stands often consistof low, shrubby trees.
Black oak 227California buckeye 235Canyon live oak 239Interior live oak 264Mixed oak 277
Montane riparian hardwoodsFrom ~3,600-8,000 ft. In canyons and along streams. Riparianlive oak stands consist of tall trees with spreading crowns.
Aspen (1 grove, San Bernardino Mts) 220California bay 234Canyon live oak 239Interior live oak 264White alder 319
Conifer and Conifer/ Hardwood Forests
North Central Coast Range forestsThese occur only in the northern portion of the Central CoastEcoregion, including the Monterey District of Los Padres NF.
Douglas-fir 246Douglas-fir/ponderosa pine 249
Douglas-fir/tan oak 250Redwood 300Santa Lucia fir 302
Cypress and coastal pineFrom sea-level to 5,500 ft. Uncommon, localized habitats.
Coastal pine forestBishop pine 225Monterey pine 280Torrey pine 346
Lower montane conifer/hardwoodFrom ~3,000 to 5,500 ft. Stands frequently patchy andsurrounded by chaparral. They intermix with montane coniferat upper elevations. Live oak understory is common.
Foothill pine/oak forestUsually open stands, conifers even-aged, shrubs orgrass below.
Coulter pine 243Coulter pine/canyon live oak 244Foothill pine (grey, foothill,digger) 257Knobcone pine 269
Bigcone Douglas-fir forestUsually dense, multi-layered stands on steep slopes incanyons.
Bigcone Douglas-fir 222Bigcone Douglas-fir/canyon live oak 223
Montane coniferFrom ~5,000 to 8,500 ft.
Mixed conifer – pine/oak phaseJeffrey/ponderosa/sugar pines, live oak, black oak andincense cedar. White fir present, but seldom dominant.Oaks common in most of this type and are the dominantstand component in some areas (e.g. the southernPeninsular ranges).
Jeffrey pine/ponderosa pine 268Incense-cedar 263Mixed conifer 275
Jeffrey pineOpen Jeffrey pine stands with few associated species.Black oak, white fir and western juniper can be present.In cold, dry, high-elevation sites. Mostly eastern slopes.
Jeffrey pine 266Mixed conifer – white fir phaseWhite fir codominate with sugar and Jeffrey pine. Blackoak or live oak common in some stands. Occurs inmesic, high-elevation sites.
Mixed conifer 275White fir 321
Subalpine conifer forestsFrom 8,500 to >10,000 ft.
Limber pine 270Lodgepole pine 271Mixed subalpine forest 278
Pinyon/juniper woodlandsFrom ~3,000 to 8,500 ft. on arid desert-facing slopes.
Scrub oak chaparralScrub oak 194Scrub oak–birchleaf mt. mahogany 196Scrub oak–chamise 197Scrub oak–whitethorn 198Mixed scrub oak 174
Montane chaparralFrom 4,000 to 10,000 ft. Characterized by absence of chamiseand presence of species found only in the mountains. Usuallydense and woody.
Bush chinquapin 117Canyon live oak shrub 128Deerbrush 148Greenleaf manzanita 155Mountain whitethorn 178Huckleberry oak 160Tobacco brush 205
Live oak scrubInt. live oak scrub 161Int. live oak/cyn. live oak scrub 163Int. live oak/whitethorn scrub 164Int. live oak-scrub oak scrub 165
Interior/desert scrubFrom ~3,000 to 7,000 feet on desert-side of the mountains.These shrublands are generally sparser than those on coastalslopes.
Big sagebrush 100Black bush 108Black sagebrush (Big Bear pebble plains) 110Bladderpod-CA ephedra- narrowleaf goldenbush 111Brittlebush 114CA buckwheat-white sage 122Creosote bush 144Creosote bush-white bursage 145Cupleaf ceanothus/fremontia/oak 146Fourwing saltbush 153Joshua tree 168Mohave yucca 175Nolina 181Rubber rabbitbrush 189Scrub oak 194Shadscale 199White sage 208
Vernal poolsMontane vernal pools (not in Sawyer)San Diego Mesa vernal pools 369San Jacinto Valley vernal pools 370Santa Rosa Plateau vernal pools 371
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Other factors affecting ecosystem condi-tion in foothill savanna woodlands include thespread of non-native species (particularlyMediterranean annual grasses) and oak regen-eration problems. Introduced annual grassesgrow rapidly during spring and deplete sur-face water much earlier in the season than thedisplaced native perennial grasses (Pavlik et al.1991). This diminishes water supplies to oakseedlings. Blue, valley, and Engelmann oak arenot regenerating well in many savanna wood-lands (Holland 1976; Scott 1990). This doesnot appear to be the result of one single factorbut rather the combined effect of non-nativegrasses, grazing, and an unnatural abundanceof acorn-eating animals such as gophers andground squirrels (Borchert et al. 1989;Schoenherr 1992).
The closed-canopy coast live oak wood-lands are less threatened. Regeneration doesnot appear to be a problem and coast live oakis a vigorous crown sprouter after fires.
Cismontane Scrub and ChaparralCoastal scrub and chaparral are the domi-
nant ecological communities on the coastalside of the mountains below 5,000 feet.Coastal sage scrub occurs primarily at eleva-tions below 2,500 feet and is most widespreadin coastal valleys and plains west of the foot-hills. Chaparral occurs across a broadelevational range but is particularly abundantin lower montane and foothill areas.
Coastal sage scrub consists of drought-deciduous, soft-leaved shrubs, frequentlydominated by California sagebrush, buck-wheat, and several sage species (fig 2.12)(Mooney 1977). The extent of coastal sagescrub has been greatly reduced by conversionto agricultural, industrial, and residential land
Figure 2.11. This blue oak stand on the Los PadresNational Forest is characteristic of the oak savannasand woodlands found in broad valleys, rolling hillsand mesa tops. MARK BORCHERT
87 percent of blue oak woodlands are withingrazing allotments.
Over the past twenty years, an increasingnumber of large foothill ranches have beensubdivided and converted into ranchette-stylehousing developments. This trend is expectedto continue and perhaps intensify in the com-ing decade, particularly in the southerncounties where demand is greatest (i.e., SanDiego, Riverside, Ventura, and Santa Barbaracounties).
The trend towards increased developmentof foothill woodlands has several clear impli-cations for public land management. As theurban interface expands and increasingly sur-rounds public wildlands, demand forrecreation and other facilities increase and the
Figure 2.10. This coast live oak stand in the SanMateo Wilderness, Cleveland National Forest, ischaracteristic of dense foothill woodlands frequentlyfound in canyons and along streams. ANNE FEGE
ability to manage fire on the landscape be-comes more constrained. Second, the declineof high-quality oak woodlands on private landsincreases the significance of such habitats onpublic lands. Finally, the decline of ranchingin this region, particularly in the southerncounties, is gradually reducing the amount oflivestock grazing on public land.
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Chapter 2
Figure 2.12. Coastal sage scrub, like this area inRiverside County, is dominated by soft-leavedshrubs. JAN BEYERS
use (Davis et al. 1994; O’Leary 1990). It isnow found in only about 15 percent of itsformer range in southern California (Westman1981; O’Leary 1990). The remnant stands ofcoastal sage scrub are habitat for a growingnumber of endangered taxa such as the Cali-fornia gnatcatcher (Davis et al. 1994).
Table 2.8. Acres of foothill oak woodland by mountain range. Values in parentheses are the percentage ofthose acres occurring on public lands. These figures represent land area where the specified vegetation typeis dominant. They are derived from a large-scale GIS vegetation layer that combines data from severaldifferent mapping efforts (see “Information Sources” section, chapter 1.)
Cleveland NF Los Padres NFAngeles NFSan Bernardino NF
SanDiego
Ranges
SantaAnaMts
SanJacinto
Mts
SanBernar-dino Mts
SanGabriel
Mts
CastaicRanges
S. LosPadresRanges
S. SantaLuciaRng
N. SantaLuciaRng TOTAL
Acres of FoothillWoodlandVegetation Types
Blue oak woodland 1,483(22%)
31,487(45%)
88,409(33%)
9,104(63%)
130,483(38%)
Engelmann oak woodland 4,029(45%)
21,083(12%)
17,054(5%)
Valley oak woodland 410(3%)
388(8%)
7,699(8%)
8,497(8%)
CA walnut woodland 30(100%)
3,896 3,926(1%)
Alvord oak woodland 1,617(4%)
1,617(4%)
TOTAL 14,210(53%)
2,313(52%)
18 11,207(66%)
6,071(48%)
121,844(48%)
184,492(31%)
87,697(84%)
489,082(45%)
61,297(23%)
Coast live oak woodland 10,181(56%)
2,153(52%)
18 11,177(66%)
4,178(62%)
86,073(51%)
88,384(30%)
76,976(89%)
323,476(52%)
44,243(30%)
However, our assessment area encompassesonly the upper elevational limits of coastalscrub where some of the associated rare spe-cies, including the gnatcatcher, are lessabundant or absent.
Chaparral consists of evergreen, woodyshrubs (e.g., chamise, manzanita andceanothus) (fig. 2.14). There are many typesof chaparral (table 2.7) and they vary widelyin species composition (Gordon and White1994). In general, chaparral is abundant in the
A major factor affecting ecosystem healthin coastal sage scrub is fire frequency. This typeof vegetation burns easily and is capable ofreburning only one or two years after a previ-ous fire. Frequent reburns result in theconversion of these shrublands to annual, non-native grasslands (Zedler et al. 1983) (fig 2.13).Since this ecosystem is increasingly adjacentto or surrounded by the urban interface, it isbecoming more difficult to prevent frequentfires and subsequent habitat degradation.
28
Fire regimes are the primary ecosystemhealth issue in chaparral and much has beenwritten on the subject (see Keeley and Scott1995). The frequency, seasonality, size, and in-tensity of fires are all important. There are avariety of different life history strategies that
assessment area and well represented on pub-lic lands (table 2.9). Only a few chaparralassociations are considered relatively rare andpoorly represented on public lands: southernmixed chaparral, ceanothus chaparral, and ser-pentine chaparral.
shrub species use to survive in a fire-prone en-vironment. Some species are short-lived, otherslong-lived. Some rely primarily on resproutingafter fire; others regenerate primarily from seed(Keeley 1986; Zedler 1995). These strategiesaffect a species’ resilience to changing fire re-gimes. However, studies suggest that mostchaparral shrubs appear to be resilient to fire-return intervals of anywhere from twenty-five toone hundred years (Keeley 1986; Zedler 1995).
The natural fire-return interval in chapar-ral is a widely debated issue, but recent research
Table 2.9. Acres of cismontane chaparral and scrub by mountain range. Values in parentheses are the percentof those acres occurring on public lands. These figures represent land area where the specified vegetationtype is dominant. They are derived from a large-scale GIS vegetation layer that combines data from severaldifferent mapping efforts (see “Information Sources” section, chapter 1.)
Cleveland NF Los Padres NFAngeles NFSan Bernardino NF
SanDiego
Ranges
SantaAnaMts
SanJacinto
Mts
SanBernar-dino Mts
SanGabriel
Mts
CastaicRanges
S. LosPadresRanges
S. SantaLuciaRng
N. SantaLuciaRng TOTAL
Coastal sage scrub 28,174(33%)
2,664(2%)
18,091(14%)
31,397(51%)
65,714(19%)
91,028(52%)
21,181(37%)
22,418(58%)
313,627(38%)
32,960(25%)
Buckwheat/white sage 5,891(90%)
7,706(58%)
23.044(55%)
5,058(69%)
33,707(68%)
105,082(78%)
353(84%)
209,108(69%)
28,267(52%)
Northern mixed chaparral 103,172(80%)
41,092(80%)
81,654(79%)
253,302(90%)
136,663(86%)
635,929(89%)
132,205(78%)
184,195(88%)
1,785,649(83%)
217,080(60%)
Southern mixed chaparral 5,994(15%)
77,544(36%)
71,550(38%)
Chamise chaparral 54,112(61%)
39,979(51%)
33,735(54%)
32,183(84%)
57,994(63%)
64,040(66%)
68,286(42%)
53,988(63%)
534,463(57%)
130,146(49%)
Scrub oak chaparral 7,016(89%)
384(92%)
15,999(62%)
443(86%)
5,317(9%)
18,003(84%)
5,482(89%)
3,267(55%)
89,357(69%)
33,446(67%)
Montane chaparral 121(100%)
3,928(73%)
28,163(90%)
23,416(99%)
17,944(99%)
86,824(88%)
13,252(52%)
Redshank chaparral 106,576(61%)
213,654(63%)
107,078(66%)
Ceanothus chaparral 1,147 409 333 14,932(18%)
3,830 2,583(52%)
23,234(18%)
Serpentine chaparral 7,473(17%)
7,473(17%)
TOTAL 204,480(68%)
202,329(62%)
201,903(66%)
346,316(86%)
299,728(63%)
946,958(82%)
231,337(62%)
273,924(78%)
3,340,754(71%)
633,779(54%)
Acres of CismontaneChaparral and ScrubVegetation
29
Chapter 2
Figure 2.13. Coastal sage scrub that reburns severaltimes in rapid succession becomes degraded anddominated by non-native, annual grasses. JAN BEYERS
Figure 2.14. Northern mixed chaparral along theupper San Diego River, Cleveland National Forest.Chaparral is much denser than coastal scrub andthe shrubs have hard, woody stems. ANNE FEGE
suggests a typical interval of fifty to seventyyears (Minnich 1995; Zedler 1995; Conardand Weise 1998). Across most of the land-scape, current fire-return patterns in chaparralappear to be either within or near this fifty toseventy year interval. Only in fire-prone areasadjacent to the urban interface are burns oc-curring more frequently.
Another widely debated issue is whetherthe average size and intensity of chaparral fireshave increased as a result of fire suppression.Some evidence suggests it has (Minnich 1989,1995), while other evidence suggests that largeconflagrations have always dominated chap-arral fire regimes (Byrne et al. 1977; Moritz1997). This subject is addressed in detail inthe chapter 3 section on fire. Whether theyrepresent a change from historic conditions
or not, large fires tend to create a homoge-neous vegetation pattern, with large tracts ofbrush in a single age class. This simplified age-class mosaic, while not a problem for theshrubs themselves, reduces habitat diversity,which generally leads to a reduction in wild-life diversity. Game animals like quail and deer,which tend to be habitat edge species, gener-ally avoid large, unbroken tracts of chaparral.The continuous fuels also may make large firesmore likely to recur.
and coast live oak, and black oak are the pri-mary tree species on lower mountain slopesbetween 3,000 and 5,500 feet elevation incentral and southern portions of the assess-ment area (table 2.10). In the northern ranges,lower montane forests can extend down to1,000 feet elevation and contain Californiabay, Pacific madrone, gray pine, and knobconepine (Griffin and Critchfield 1976). Oftendescribed as mixed evergreen forests (Munzand Keck 1973), they are typically found insmall, scattered patches (roughly 50 to 800acres in size) surrounded by large expanses ofchaparral (fig 2.15). Thus, they are highly in-fluenced by chaparral fire regimes.
Bigcone Douglas-fir and Coulter pine areessentially endemic to the coastal mountainsof central and southern California (Coulterpine extends a ways into Baja California,Mexico) (Minnich 1987; Griffin andCritchfield 1976). These conifer species arerarely found together, but both are frequentlyassociated with canyon live oak. Both arehighly influenced by chaparral fire regimes,but their life history strategies for respondingto fire are very different.
Bigcone Douglas-fir/canyon live oak for-ests frequently occur near streams in moist,shaded canyons and draws, where aspects aremostly north and east. At the upper end oftheir elevation range these forests appear onother aspects and become less restricted tocanyons (McDonald and Littrell 1976). They
30
Figure 2.15. Scattered patches of Coulter pinesurrounded by chaparral in American Canyon, LosPadres National Forest. MARK BORCHERT
are evidently not well adapted to withstandingfires and persist primarily by clinging to steep,fire-resistant terrain (Minnich 1988;McDonald 1990). Their ability to escape firessweeping through the surrounding chaparralis due to their occurrence on precipitous slopesand the formation of a dense, arboreal canopy
that limits understory fuel accumulation.These stands typically have few understoryshrubs or flammable ground cover.
Bigcone Douglas-fir forests are believed tobe negatively affected by changing fire patterns(Minnich 1988). Although there has not beena rangewide quantitative evaluation of habi-tat losses, it is widely believed that bigconeDouglas-fir has declined significantly over thelast ninety years as a result of crown fires andpoor post-fire recovery. Minnich (1999) hasdocumented an 18 percent decline in the ex-tent of bigcone Douglas-fir in the SanBernardino Mountains since 1938.
The increase in crown fires is attributed tohigher fire intensities in the surrounding chap-arral, although there is little data to substantiatethis possibility (see discussion in chapter 3 sec-tion on “Fire”). The most vulnerable stands arethose on gentler slopes: Minnich (1980) observed37 percent survival of bigcone Douglas-fir fol-lowing wildfires on slopes less than 20 degrees,
Table 2.10. Acres of lower montane forest types by mountain range. Values in parentheses are the percentageof those acres occurring on public lands. These figures represent land area where the specified vegetationtype is dominant. They are derived from a large-scale GIS vegetation layer that combines data from severaldifferent mapping efforts (see “Infromation Sources” section, chapter 1).
Acres of LowerMontane ForestTypes
Cleveland NF Los Padres NFAngeles NFSan Bernardino NF
Table 2.11. Acres of montane and subalpine conifer forest types by mountain range. Values in parenthesesare the percentage of those acres occurring on public land. These figures represent land area where thespecified vegetation type is dominant. They are derived from a large-scale GIS vegetation layer that combinesdata from several different mapping efforts (see “Information Sources” section, chapter 1).
Montane and Subalpine ConiferForests
Montane conifer forests consist of vary-ing combinations of ponderosa pine, Jeffreypine, white fir, black oak, canyon live oak,sugar pine, incense-cedar, and western juni-per (table 2.11). These forests are thedominant land cover type between the eleva-tions of 5,000 and 8,500 feet in the southernCalifornia mountains and above 3,000 feetalong the Monterey coast. Subalpine coniferforests occur above 8,000 feet and consist oflodgepole pine, limber pine, white fir, andwestern juniper (fig. 2.16).
but more than 90 percent survival on slopesgreater than 40 degrees.
Coulter pine persists in a chaparral-domi-nated environment by being adapted for rapidregeneration after fires. It has adapted to peri-odic crown fires by having a relatively shortlife span (fifty to one hundred years) and semi-serotinous cones that favor its re-establishmentafter fire (Vale 1979; Borchert 1985). As a re-sult it appears to be more resilient to today’sfire regime than bigcone Douglas-fir.
The biggest threat to Coulter pine is mul-tiple fires in short succession (e.g., less thantwenty-five years), that kill overstory trees be-fore an adequate seed crop has developed. Insuch cases stands can fail to regenerate andconvert to chaparral. Extreme insect or dis-ease outbreaks can also threaten Coulter pine.During the height of the drought in the late1980s, a major bark beetle epidemic killed ap-proximately 70 percent of overstory Coulterpines on Palomar Mountain (T.White, Cleve-
land NF, pers. comm.). Re-establishment hasbeen poor in some areas, due to brush cover.Coulter pines need openings for successful re-generation. When overstory trees die withoutan accompanying fire to clear a seed bed, seed-ling establishment can be impaired.
Cleveland NF Los Padres NFAngeles NFSan Bernardino NF
SanDiego
Ranges
SantaAnaMts
SanJacinto
Mts
SanBernar-dino Mts
SanGabriel
Mts
CastaicRanges
S. LosPadresRanges
S. SantaLuciaRng
N. SantaLuciaRng TOTAL
Mixed conifer–pine 40,082(78%)
98,062(76%)
20,494(99%)
852(99%)
159,490(80%)
Acres ofMontane ConiferForest Types
Mixed conifer–fir 26,590(85%)
53,889(96%)
37,001(95%)
152,863(78%)
35,383(26%)
Jeffrey/ponderosa pine 2,351(43%)
58,526(81%)
5,515(96%)
43,507(96%)
16,210(68%)
141,604(84%)
15,485(75%)
Black oak 3,771(88%)
4,550(70%)
369(96%)
1,248(89%)
1,538(1%)
1,014(78%)
21,070(60%)
8,580(46%)
Redwood/Santa Lucia fir 16,658(69%)
16,658(69%)
Subalpine conifer 2,090(100%)
5,916(100%)
10(100%)
234(100%)
8,250(100%)
TOTAL 0 48,304(78%)
193,644(79%)
80,277(97%)
2,100(93%)
80,742(96%)
1,538(1%)
33,882(69%)
499,935(79%)
59,448(42%)
32
To validate these predictions we examinedexisting and newly collected data on vegeta-
Figure 2.16. Continuous stands of mixed coniferforest give way to alpine habitats on Mount SanGorgonio, San Bernardino National Forest. JOHN
STEPHENSON
Some montane conifer stands havechanged dramatically since the early 1900s,largely due to long-term fire exclusion(Minnich et al. 1995). Fire suppression hasbeen extremely effective in upper mountainforests. Low- to moderate-intensity understoryfires, which were historically frequent occur-rences in these forests (i.e., every fifteen tothirty years) (McBride and Lavin 1976), havebeen virtually eliminated over the last sixty toeighty years. Resulting problems include (1) alarge increase in the number of understorytrees (particularly shade-tolerant white fir andincense-cedar); (2) increased risk of stand-re-placing crown fires due to fuel buildup; and(3) increased mortality and reduced recruit-ment of large trees (due to increasedunderstory competition).
These problems are occurring primarily inmesic forests where understory trees developrapidly. Stand densities in arid, desert-side for-ests do not appear to be experiencingsignificant change. To estimate the spatial ex-tent of the problem, we developed a GIS-basedmodel to predictively map areas likely to beexperiencing overcrowded forest conditionsand associated crown fire risk. Spatial data onvegetation type, canopy cover, annual precipi-tation, elevation, and slope were used topredict potential problem areas (table 2.12)(fig. 2.17).
tion changes at plot locations established dur-ing the Vegetation Type Map (VTM) Survey(Weislander 1935). Approximately 18,000VTM plots were initially surveyed from 1929to 1934 as part of a project to map the vegeta-tion of California (Minnich et al. 1995). Theyprovide a valuable record of what the vegeta-tion structure and composition was over sixtyyears ago.
Minnich et al. (1995) revisited sixty-eightVTM plots located in montane conifer forestsin the San Bernardino Mountains. Using dif-ferent methods, Savage (1994) studied thissame issue in the San Jacinto Mountains. Toobtain data from additional mountain ranges,we revisited thirty-two VTM plots in theMount Pinos/Mount Abel area, the SanGabriel Mountains, and the mountains of SanDiego County.
The results from each area were very simi-lar: Mid-elevation mixed conifer forests haveexperienced (1) substantial increases in thenumber of small diameter trees (fig. 2.18), (2)reductions in the number of large trees, and(3) shifts in species composition towards morewhite fir and incense-cedar and fewer Jeffrey/ponderosa pine and black oak. In contrast,plots in Jeffrey pine forests on the more arid,desert side of the mountains showed littlechange.
Subalpine forests in southern Californiaoccur only in the highest ranges: the SanJacinto, San Bernardino, and San Gabrielmountains and small patches on the summitof Mount Pinos and Mount Abel. Most ofthese areas are within designated wildernessareas, including the largest stands on the slopesof Mount San Gorgonio. In general, thesesmall subalpine/alpine ecosystems are intact,stable, and little disturbed (with the exceptionof some heavy recreation use in the vicinity ofmountaintop trails). Trees grow very slowly inthese upper elevation forests and stands tendto be open.
Fires are naturally infrequent in subalpineforests and thus return intervals have not beensignificantly altered by suppression activities.When they do burn, it is usually in a stand-replacing crown fire during severe weather
33
Chapter 2
conditions (Minnich 1988). Several crownfires have occurred in recent decades in subal-pine forests in the San Gabriel Mountains.While the result of human-caused ignitions,it is unclear if these fires were abnormally se-vere or frequent. The extremely steep terrainin the San Gabriels may make these forestsmore vulnerable as human-caused fire igni-tions increase.
Figure 2.18. A look at how stem densities by size class have changed in mixed conifer stands over thelast sixty years. The left graph comes from VTM plots done in the early 1930s and the right graph comesfrom those same locations in 1997 (n = 7). Each bar represents +/- one standard deviation from themean; the mean is indicated by the horizontal line through each bar. Pronounced increases in stemdensities have occurred in the small diameter size classes, while the number of large diameter (>90cm) trees has slightly declined. These results are from the mountains of San Diego County, but thesame trend is seen in plot data from the San Bernardino Mountains (Minnich et al. 1995), the SanGabriel Mountains and Mount Pinos.
Areas predicted to be experiencing high stand densification meet all of the following
conditions:
1. Vegetation type is a conifer forest (but not bigcone Douglas-fir or pinyon/juniper)
2. Elevation is at or below 7,500 feet
3. Average annual precipitation is greater than 65 centimeters (25.6 inches)
4. Canopy cover is greater than 60 percent
5. Slope is less than 60 percent
Table 2.12. Description of the model conditions used to predict areas of montane conifer forestwith overcrowded stand conditions. The map of predicted areas is shown in figure 2.17.
Desert Montane CommunitiesArid slopes on the desert side of the moun-
tains are occupied by sparse pinyon-juniperwoodlands, semi-desert chaparral, sagebrush,and desert scrub (table 2.13). Single-leaf pin-yon pine generally dominates the higherelevation slopes, while California juniper isprevalent at lower elevations, often on gentleslopes or alluvium. Parry or four-needle pin-yon pine occurs in the San Jacinto Mountainregion’s desert transition zone near ThomasMountain.
Semi-desert chaparral is more open thanchaparral found on coastal slopes and has adifferent mix of species. Flannel bush, bitter-brush, Tucker or Miller scrub oak, birchleafmountain mahogany, and cupleaf ceanothusare characteristic components of semi-desertchaparral (Sawyer and Keeler-Wolf 1995).Basin sagebrush is common in dry alluvialfans, meadows, and washes. Basin sagebrushis particularly prevalent in the low elevationssurrounding Mount Pinos and in the GarnerValley region south of Mount San Jacinto.There is no evidence that fire regimes in thesevegetation types are outside the range of natu-ral variability.
Common land uses in desert-side habitatsare mining, off-highway vehicle (OHV) rec-reation, and target shooting. Large limestonedeposits in the northeastern portion of the SanBernardino Mountains have resulted in thedevelopment of several major open-pit mines.Exploratory drilling for oil and gas deposits isa major activity in the southern Los Padres.These activities have caused habitat losses andare affecting sensitive resources in some
Pinyon-juniper woodlands are generallyopen-canopy stands with sparse understoryvegetation. It is not a vegetation structure thatcarries fire well and pinyon pine is not adaptedto frequent fire. Fire-return intervals of sev-eral hundred years are considered typical inthese woodlands (Minnich 1988).
There have recently been several large firesin pinyon stands in the San Bernardino Moun-tains. One area even reburned several yearsafter a crown fire (S. Loe, San Bernardino NF,pers. comm.), which is very unusual in suchsparsely vegetated habitat. This has raised con-cern about whether the spread of introducedgrasses (primarily cheatgrass) is providing thefuels needed for fire to carry more effectivelyand frequently in these stands. If this is oc-curring, it would only be in years of highprecipitation when there is sufficient moisturefor the grass to become widespread. It is un-clear if this is actually happening, but the issuewarrants further study because pinyon-juni-per woodlands are extremely slow to recoverfrom fire and would be negatively affected byshortened fire-return intervals. Black stain rootdisease is also a significant problem for pin-yon pine, particularly in portions of the San
Table 2.13. Acres of desert-side montane vegetation types by mountain range. Values in parentheses are thepercentage of those acres occurring on public lands. These figures represent land area where the specifiedvegetation type is dominant. They are derived from a large-scale GIS vegetation layer that combines datafrom several different mapping efforts (see “Information Sources section, chapter 1).
Cleveland NF Los Padres NFAngeles NFSan Bernardino NF
SanDiego
Ranges
SantaAnaMts
SanJacinto
Mts
SanBernar-dino Mts
SanGabriel
Mts
CastaicRanges
S. LosPadresRanges
S. SantaLuciaRng
N. SantaLuciaRng TOTAL
Pinyon woodland 13,225(83%)
57,776(89%)
26,065(79%)
17,029(12%)
236,780(86%)
351,337(82%)
444(91%)
Semi-desert chaparraland Tucker scrub oak
37,354(67%)
50,021(83%)
48,569(70%)
5,332(20%)
78,632(86%)
160(57%)
247,182(78%)
27,114(83%)
Basin sagebrush 15,416(30%)
8,282(76%)
2,856(37%)
1,678 15,373(54%)
50,466(43%)
6,861(25%)
Desert scrub 26,170(52%)
4,466(47%)
54 35,658(58%)
4,968(100%)
TOTAL 92,165(59%)
120,545(84%)
77,544(72%)
24,039(13%)
330,785(85%)
160(57%)
0 684, 643(77%)
39,387(75%)
Acres of Desert-side MontaneVegetation Types
0
35
Chapter 2locations, but from a broad ecosystem perspec-tive they are relatively localized.
Target shooters and OHV enthusiasts tendto concentrate in desert-side habitats becausethe sparsely vegetated terrain is conducive tothese activities. Uncontrolled target shootinghas raised safety and pollution (particularlyfrom lead accumulation) concerns and severalof the national forests are currently reviewingtheir policies on this activity.
Monterey Coast CommunitiesThe northern Santa Lucia Range along
the Monterey coast receives substantiallyhigher amounts of precipitation than the restof the assessment area and thus contain plantcommunities that are more similar to thosefound in northern California. Along the im-mediate coast, narrow stands of redwood treesoccur in deep canyons surrounded by coastalscrub, chaparral, and grassland.
On the inland side of the mountain crest,stands of ponderosa pine, the endemic SantaLucia fir, and true Douglas-fir (a differentspecies than bigcone Douglas-fir) occur at thehighest elevations. Below the conifer belt onthe inland side of the mountains is a mosaicof chaparral, mixed evergreen forest, and oakwoodland. California bay, Pacific madrone,and live oak are common components of theevergreen forest. This is the only place in theassessment area where Douglas-fir and mad-rone are common trees.
Although fires are generally smaller andless frequent in this mesic area, a single event(the approximately 180,000-acre MarbleCone fire) burned much of the region in thelate 1970s (Griffin 1982; Moritz 1997). It isunclear if this is a typical historic pattern, butthere is little evidence to suggest that the areais experiencing vegetation changes as a resultof shifting fire regimes.
Rugged terrain in the area historically lim-ited road development and led to theestablishment of the Ventana Wilderness,which encompasses the majority of the north-ern Santa Lucia Range. Land use in this regionis relatively limited and strongly recreation ori-
ented. The Big Sur coastline receives most ofthe recreation activity.
Aquatic and RiparianCommunities
Freshwater aquatic habitats are uncom-mon in coastal southern California and mosthave been substantially modifed by alteredstream flow regimes. Essentially all the largerivers are to some extent dammed or diverted(figs. 2.19–20), thereby significantly alteringthe extent and character of riverine habitats(see section on “The Influence of Water Regu-lation and Withdrawal” in chapter 3).Deep-water reservoirs formed by dams are anew and entirely different type of aquatic habi-tat that didn’t exist historically in the region.The aquatic fauna found in these reservoirstends to be dominated by non-native species.
Given the dominant role that impound-ments have in determining a drainage’s habitatpotential, we partitioned streams into analy-sis watersheds based on whether they occurredabove or below major impoundments. A da-tabase was developed that provides baselineinformation on each analysis watershed and themajor streams occurring within them. Informa-tion compiled for each stream includes linearmiles by elevation intervals, percent on publicland, occurrence of roads along the stream cor-ridor, land use intensity, degree of stream flowalteration, and level of non-native species infes-tation. Information on each watershed includesthe percent of the entire watershed that is onpublic land, road densities in the watershed, andoccurrences of both species of concern and in-vasive non-native species. A complete table ofthe data compiled for each watershed and streamis provided in appendix C.
Streams and Rivers
Most streams in southern California havevery low flow during the summer months andin many cases dry up in the lower and upper-most portions. However, streams that flowthrough rock canyons often have perennialflow because deep pools are fed by ground-water recharge. This pattern of low flow in
36
Figure 2.19. The primary rivers and streams in the southern portion of the assessment area with the underlyingpublic lands. Shown in red are locations of dams (circles) and major diversions (triangles). Baldwin Lake, theonly large natural lake in the region, can be seen in the upper right, just west of Arraste Creek.
summer, which reflects the Mediterranean cli-mate, results in an interesting situation inwhich the headward parts of streams may bedry, the middle portion wet, and the low por-tion dry during the summer months (Faber etal. 1989).
The middle and lower portions of thesestreams, typically found at elevations below3,000 feet, support a higher number of aquaticand riparian species. Perhaps because habitatloss has been so extensive there, low-elevationstreams also have a much higher number of
37
Chapter 2
Figure 2.20. The primary rivers and streams in the northern portion of the assessment area with the underlyingpublic lands. Shown in red are locations of dams (circles) and major diversions (triangles).
associated threatened, endangered, and sensi-tive (TES) animal species (table 2.14).
Landownership patterns and threat fac-tors also differ dramatically by elevation.Seventy-four percent of stream miles above3,000 feet elevation are on public lands, butthis proportion drops to 50 percent between1,000 and 3,000 feet, and down to 17 per-
cent below 1,000 feet (fig 2.21). The low-elevation rivers also face greater threats.Water flows are much more likely to be di-verted or altered, the adjacent terraces arecommonly farmed or developed, and there isa greater abundance of invasive non-nativespecies.
38
Given the significance and rarity of hy-drologically intact low-elevation streams, thoseoccurring on public lands should be givenspecial attention. Of particular import are thesections of these streams that are in a relativelyunmodified state. These are the areas wherehistoric disturbance regimes and the naturalrange of variability may still be possible tomaintain. To identify these areas we used GISdata to select the low-elevation streams bestrepresented on public lands and the sectionsof them that do not contain upstream damsor diversions. Then we considered informa-tion on land use intensity, invasive species, andlandownership patterns in the upstream wa-tershed (table 2.15).
The streams listed in table 2.15 are notnecessarily the most important ones in termsof TES species populations. However, the hy-drologically unregulated sections of thesestreams are likely to be the best remaining ex-amples of intact low-elevation aquaticecosystems in the central and southern Cali-fornia coastal region. Thus, they represent ourbest opportunities for maintaining intactaquatic ecosystems.
Next to alteration of stream flow, the big-gest factor threatening the health of nativeaquatic ecosystems is the spread of invasive
Figure 2.21. Bars show the miles of all streamsalong the central and southern California coast byelevation group. The shaded portion is theproportion that occurs on public land, with thepercent value shown above it. The occurrence ofstreams on public lands increases dramatically withelevation.
non-native species. Invasive aquatic animalsthat are causing problems in many streamsinclude green sunfish, bluegill, bullfrogs, cray-fish, mosquitofish, brown trout, bass,bullheads, red-eared sliders, and Africanclawed frogs. The invasive plants arundo andtamarisk are also spreading, displacing nativevegetation and causing a decline in surface
Table 2.14. Threatened, endangered, and sensitive (TES) aquatic and semi-aquatic animal species thatare associated with either low- or high-elevation streams.
Aquatic TES animals found primarily inlow-elevation streams (<3,000 ft)
California red-legged frog
Foothill yellow-legged frog
Coast range newt
Southwestern arroyo toad
Santa Ana sucker
Santa Ana speckled dace
Arroyo chub
Southern steelhead
Unarmored threespine stickleback
California red-sided garter snake
Southwestern pond turtle
Aquatic TES animals found primarily inhigh-elevation streams (>3,000 ft)
Mountain yellow-legged frog
Shay Creek stickleback
74%50%
17%
0
500
1000
1500
2000
2500
Streamsbelow1,000 ft
Streams1,000 to3,000 ft
Streamsabove3,000 ft
mile
s of
str
eam
on private landon public land
39
Chapter 2
water availability in some streams (Rieger andKreager 1989). Collectively, these introducedspecies are causing a serious decline in the ca-pability of aquatic habitats to support nativespecies.
Table 2.15. The most significant low-elevation (below 3,000 feet) streams from the standpoint oflinear miles on public lands. Those in bold are identified as having relatively high potential for maintainingaquatic ecological integrity, due to a high amount of unregulated streamflow (i.e., not dammed ordiverted).
Lakes
Almost all lakes in the assessment area areman-made reservoirs formed by dams. How-ever, a few small natural basins exist that holdwater all or most of the time. The majority ofthese straddle the San Andreas Fault: Jackson
* These streams are predominately on military lands.
** The flow on the Santa Margarita is partially diverted by a dam on Temecula Creek.
San Antonio River* No. Santa Lucia 56.0 47.7 64% Mod ?
Nacimiento River* No. Santa Lucia 34.6 25.1 48% Mod ?
Piru Creek So. Los Padres 26.6 7.3 80% High High
Sisquoc River So. Los Padres 26.4 26.4 87% Low Low
Santa Ynez River So. Los Padres 26.1 0 High High
Big Sur River (S & N fks) No. Santa Lucia 25.7 25.7 93% Low Low
Sespe Creek So. Los Padres 23.9 23.9 91% Mod Mod
San Mateo Creek Santa Ana Mts. 22.8 22.8 92% Low Mod
Santa Margarita River** San Diego Ranges 21.4 21.1** 38% Mod High
Santa Ana River San Bernardino Mts. 17.6 0 87% Mod High
San Gabriel River San Gabriel Mts. 17.6 12.5 95% High Mod
Arroyo Seco No. Santa Lucia 16.5 16.5 60% Mod Mod
West Fk, San Gabriel R. San Gabriel Mts. 15.7 6.0 100% Mod Mod
Cuyama River So. Los Padres 14.8 4.5 70% Mod ?
Manzana Creek So. Los Padres 14.3 14.3 100% Low Low
Carmel River No. Santa Lucia 14.0 5.0 49% Mod Low
Elizabeth Lake Liebre Mtn. Area 13.4 13.4 84% High Mod
Salinas River N&S Santa Lucia 13.1 2.2 22% High High
San Diego River San Diego Ranges 13.0 7.9 42% Low/Mod Mod
Mono Creek So. Los Padres 13.0 13.0 96% Low Low
San Juan Creek Santa Ana Mts. 12.2 12.2 52% High Mod
Big Tujunga Creek San Gabriel Mts. 11.4 0 87% High High
Pine Valley Creek San Diego Ranges 10.3 10.3 81% Low Mod
Indian Creek So. Los Padres 9.5 9.5 100% Low Low
Santa Cruz Creek So. Los Padres 9.4 9.4 58% Mod ?
InvasiveSpeciesInfestation
Stream Miles below 3,000ft
Stream Mountain RangeSubarea
OnPublicLand(Total mi)
FlowUndivertedon PublicLand
% PublicLand inWatershed
Land UseIntensity
40
Riparian habitats have declined dramati-cally at low elevations, where they historicallywere most extensive. It is estimated thatchannelization and diversion of streams in thelast century have reduced the extent of ripar-ian habitats in southern California by over 90percent (Faber et al. 1989). More recently,strong regulatory policies on “no net loss” ofwetlands have helped to check this decline.
The extent of riparian habitats on publiclands is relatively stable. So too is the struc-tural condition of these habitats. Livestockgrazing in riparian areas within the nationalforests has been substantially reduced, result-ing in some dramatic improvements invegetation condition. Concentrated recreationuse is causing localized habitat damage in someareas. Foothill riparian areas are cool, pleas-ant places in the vicinity of large urbanpopulations so recreation pressure is inevitable.
Low-Elevation Riparian Habitats
Riparian habitats reach their peak as dis-tinct ecological communities along mid- tolarge-order streams below 4,000 feet in thefoothills and valleys. There are many differ-ent riparian plant associations (table 2.7), butfoothill riparian woodlands generally fall intoone of three broad categories: (1) Fremont cot-tonwood/willow, (2) California sycamore/coast live oak and (3) white alder (Borchertunpubl. manuscript). They are extremely pro-ductive and important habitats for wildlife (seeFaber et al. 1989 for an excellent overview ofsouthern California riparian habitats).
Figure 2.22. Linear riparian woodlands like this onein San Francisquito Canyon, Angeles National Forest,contrast sharply with the surrounding aridshrublands. SHAWNA BAUTISTA
Lake, Elizabeth Lake, Lake Hughes, and LostLake. In addition, Crystal Lake in the San GabrielMountains, Dollar Lake in the San BernardinoMountains, and Hidden Lake in the San JacintoMountains are small natural lakes.
There is one large natural, ephemeral lakein the mountains: Baldwin Lake in the east-ern San Bernardino Mountains. This largeshallow basin fills with water during wet peri-ods. It can retain water year-round for severalyears when conditions are right. When full,its shallow waters attract large numbers of wa-terfowl and also provide habitat for the rareShay Creek stickleback fish. The watershedthat feeds Baldwin Lake is also the primarywater supply for the community of Big BearCity. This may be resulting in reduced flowsinto the lake.
The large, man-made lakes are essentiallydistinct ecosystems, with an aquatic fauna thatbears little resemblance to what naturally oc-curs in the streams that formed them. Almostall support fisheries and are stocked with vari-ous species of bass, trout, catfish, and sunfish.Fishing is a very popular recreational activityat many of these lakes, attracting far more an-glers than do the streams. The lakes have alsoattracted species such as bald eagle and ospreythat were formerly very rare in these moun-tains. These lakes also facilitate theintroduction of a wide variety of invasive non-native species into the surrounding streams(see “Invasive Species” section, chapter 3).
Riparian ecosystems are linear and oftennarrow features on the landscape (fig. 2.22).For that reason, they are difficult to accuratelymap across large areas using air photos or sat-ellite imagery. Our existing vegetation mapsdo not fully capture the distribution of ripar-ian habitats; thus, we have not attempted toprovide acreages for them. A detailed map ofriparian plant communities would be ex-tremely useful for management purposes.Related information on the extent of rivers andstreams in the region is provided in the sec-tion on aquatic ecosystems.
41
Chapter 2However, habitat degradation tends to be lo-calized in a few popular, easily accessible areas.
A more insidious and widespread prob-lem is the spread of invasive, non-nativespecies. The brown-headed cowbird, whichparasitizes the nests of native birds, and Eu-ropean starlings, which displace nativecavity-nesting birds, are causing declines inhabitat capability in many areas. Bullfrogs,African clawed frogs, and green sunfish arespreading in many drainages, causing largeimpacts on native amphibians, aquatic rep-tiles, and fish. Arundo (giant cane) andtamarisk are invasive plants that areoutcompeting native riparian vegetation insome areas. Arundo in particular is spreadingrapidly in low-elevation riparian areas.
Twelve rare ecological communities wereidentified in the assessment area. Communitiesfall into this category if there is some concernover their ability to persist in the region. Fourare defined by unusual soils and eight are plantcommunities either narrowly distributed withinthe assessment area or threatened in a portion oftheir natural range. Acreage estimates for thetwelve communities are summarized in table2.16 and brief descriptions follow.
Valley Oak WoodlandsValley oak (Quercus lobata) is endemic to
California, occurring in areas with relativelymild winters west of the Sierra Nevada Moun-tains (Axelrod 1977). The species formsextensive woodlands, some of which occur inthe northern half of our assessment area.
Table 2.16. The extent and distribution of rare community types on public lands. Acreages are derivedfrom GIS coverages of vegetation, species, and soils distributions.
Valley oak woodlands unknown <20% 8% (680)
Engelmann oak woodlands 53,8102 82% 12% (6,461)3
Black walnut woodlands 23,5694 17% 12% (2,828)
Cuyamaca cypress groves 230 100% 100%
Tecate cypress groves 6,758 15% 85% (5,744)
Gabbro outcrops 81,680 55% 41% (33,489)
Montane meadows 55,446 100% 38% (21,070)
Pebble plains 379 100% 60% (227)
Limestone/carbonate 20,893 90% 87% (18,177)
outcrops
Serpentine outcrops unknown (31,470)
Sargent cypress groves 1,585 100% 74% (1,173)
Santa Lucia fir forests 7,576 100% 95% (7,197)
1 based on bioregions as defined by the California Bioregional Council2 calculated using top four cover classes (3, 4, 5, and 6) from Scott (1990)3 includes private reserves (e.g., portions of the Santa Rosa Plateau)
4 from mapped polygons by Weislander (1935)
Rare CommunitiesTotal MappedAcres in Centraland South CoastBioregions1
Percent withinAssessmentArea
Percent on PublicLands withinAssessment Area(acres)
Rare Communities
42
Figure 2.23. Valley oak woodland at Wagon CavesCandidate Research Natural Area, Los Padres NationalForest. MARK BORCHERT
Valley oak frequently forms open wood-lands with a grass-dominated understory.These oak savannas are often the dominantplant community in broad valleys that sur-round the mountains of Santa Barbara, SanLuis Obispo, and Monterey counties. Alongdrainages the species forms denser riparianforests (Holland 1986) and is often foundwith blue oak, black oak, coast live oak, sy-camore, and black walnut (Sawyer andKeeler-Wolf 1995).
Valley oak woodlands are poorly repre-sented on public lands, although a moredetailed mapping effort is needed to betterquantify the exact amount. On private lands,the rapid expansion of agriculture and urbandevelopment along the central coast is caus-ing a serious reduction in the extent of thesewoodlands (R. Cowan, The Quercus Group,in litt. 1998). For example, the clearing ofoak savannas for large vineyard operations isoccurring in the foothills and valleys of SantaBarbara County. More than 2,500 oaks in theSanta Ynez and Los Alamos valleys have beenfelled during the last two years and countyofficials predict vineyard acreage to triplewithin ten years (Cannon 1998). These areasare outside the assessment area but illustrate
the importance of valley oak conservation onpublic lands.
Tree regeneration is also considered a prob-lem in valley oak woodlands. Many stands arereported to be especially devoid of trees estab-lished in the last 75 to 125 years (Pavlik et al.1991). Factors cited as contributing to this lackof regeneration include consumption of acornsand seedlings by livestock, tilling of croplandaround mature trees, lowering of the watertable through groundwater pumping, andcompetition from non-native grasses and otherexotic species (C. Blair, CNPS, in litt. 1998).The presence of non-native annual grasses innative grasslands has been shown to increaseoak seedling mortality by limiting the avail-ability of soil moisture (Danielsen andHalvorson 1991). Non-native annual grassesgrow and utilize soil moisture faster than na-tive perennial grasses. Oak seedlings exposedto rapid declines in soil moisture experiencewater stress and display reduced growth. Incontrolled experiments, Danielsen andHalvorson (1991) found that valley oak seed-lings were significantly larger when growingin association with native purple needlegrass(Stipa pulchra) than when grown with wild oats(Avena fatua).
Engelmann Oak WoodlandEngelmann oak (Quercus engelmannii)
woodlands are distributed from the SanGabriel Mountains south to Baja California,Mexico; however, most occur in the foothills
Valley oaks are most prevalent at low eleva-tions in the Santa Lucia Ranges but also extendinto portions of the southern Los Padres andCastaic regions, and the northern flank of theSan Gabriel Mountains (Hickman 1993; Grif-fin and Critchfield 1972). The southernmostoccurrences of valley oak woodland are foundin Los Angeles County in the San Fernandoand Santa Clarita valleys and the Santa MonicaMountains (Pavlik et al. 1991).
True to its name, this tree typically occu-pies valley floor and lower foothillcommunities where there are deep soils (fig.2.23). Its distribution also appears to be asso-ciated with shallow water tables (Griffin 1977).Valley oaks do extend up the mountain slopesin places. They occur at 5,000 feet on ChewsRidge in the northern Santa Lucia Range andextend up to 5,600 feet in the TehachapiMountains.
43
Chapter 2of San Diego and southwestern Riversidecounties (fig. 2.24). Populations also occur onSanta Catalina Island. The greatest concen-tration of these woodlands is found in thefoothills of San Diego County betweenPalomar Mountain and Cuyamaca Peak. An-other major occurrence is located on the SantaRosa Plateau on the southeastern flank of theSanta Ana Mountains. The species is the onlyrepresentative of subtropical white oaks inCalifornia and represents the northwesternextent of their range (Scott 1990).
Figure 2.24. The distribution of Engelmann oak and black walnut in southern California.
Engelmann oaks are found at elevationsranging from 160 to 4,500 feet on valley floors,foothill slopes, and raised stream terraceswithin riparian corridors (Scott 1989; Sawyer
and Keeler-Wolf 1995). They commonly formopen savannas (less than 10 percent canopyclosure) and woodlands (greater than 10 per-cent canopy closure) with grasslandunderstories (R. Cowan, The Quercus Group,in litt. 1998)(fig. 2.25). In riparian areas thespecies can occur in dense stands with otherhardwoods (Holland 1986).
Some of the most successful stands ofEngelmann oak grow on clay soils formedfrom a gabbro or basalt substrate (St. John1992). In San Diego County the species issometimes found on rocky, north-facing slopeswith an understory of coastal sage scrub orchaparral. In these instances it often hybrid-izes with scrub oak or Muller’s oak.
44
Acreage estimates for this woodland typevary depending on whether Engelmann oakis mapped everywhere it occurs or just whereit is the dominant tree. Based on our GIS veg-etation layer, Engelmann oak woodland is thedominant vegetation type over an estimated21,083 acres—17,054 acres in San DiegoCounty and 4,029 acres in the Santa Rosa Pla-teau region. In contrast, Tom Scott used aerialphotographs and ground-truthing to map ap-proximately 78,000 acres that contain at leastsome Engelmann oak (it was subdominant tocoast live oak in over half of this area)(Scott1989). Rarely does the species occur in purestands (over less than 1,300 acres based onScott’s map). Seventy-eight percent of the En-gelmann oak mapped by Scott occurs withinthe assessment area, with the remaining acreslocated to the west in more coastal areas ofSan Diego County.
Engelmann oak woodlands are decliningprimarily due to habitat loss on private lands.Eighty-eight percent of Engelmann oak habi-tat in the assessment area is located on privateland (Scott 1989). The tree inhabits the small-est natural range of any oak species inCalifornia and is located next to the fastestgrowing urban landscape in the country (Scott1990). Encouraging private landholders toprotect this species on their properties is keyto conserving Engelmann oak (T. Scott, UCRiverside, in litt. 1998). In addition, it is im-portant for public land management agencies
Figure 2.25. A mix of Engelmann and coast liveoak form a relatively open woodland on theRutherford Ranch, Cleveland National Forest. STAN
CALHOUN
to pursue acquisition of lands containing En-gelmann oak when they come up for sale. Inrecent years, major progress has been made inconserving this species through the purchaseof key areas by Riverside County (on the SantaRosa Plateau), San Diego County (on VolcanMountain), CalTrans, and the Cleveland Na-tional Forest (Roberts and Rutherfordranches).
The primary management concern forEngelmann oak woodlands on public lands ismaintaining sufficient regeneration. The long-term viability of Engelmann oak appears tobe hampered by sporadic regeneration com-bined with unnatural rates of disturbance.Livestock grazing and competition for soilmoisture from introduced annual grasses bothappear to cause low recruitment rates for thespecies and there is a noticeable absence ofyoung trees in many woodlands (Lathrop andOsborne 1990; Pavlik et al. 1991).
Walnut WoodlandBlack walnut (Juglans californica var.
californica) woodlands are an uncommon foot-hill habitat that is distributed from SantaBarbara County south to northern San DiegoCounty (fig. 2.24). The easternmost standsoccur in southwestern San Bernardino Countyin Day, Etiwanda, and San Sevaine canyonsat the foot of the San Gabriel Mountains.Large stands also occur in Ventura, Los Ange-les, and northern Orange counties (Quinn1989; Keeley 1990). Woodlands are scatteredin low foothills surrounding the Santa ClaraRiver drainage (including the Santa Susanaand Sulphur mountains), in the Santa YnezMountains, along the north side of the SantaMonica Mountains, along the base of the SanGabriel Mountains, and in the Simi, San Jose,Puente, and Chino hills. Other stands occurwithin the lower foothills of the southern LosPadres and Castaic regions.
Black walnut can be the dominant tree inthe canopy or occur in mixed stands with otherhardwoods such as coast live oak (fig. 2.26).At Los Pinetos Spring in the western SanGabriel Mountains, walnut grows withbigcone Douglas-fir and canyon live oak
45
Chapter 2(S. Boyd, Rancho Santa Ana Botanic Garden,pers. comm.). Some isolated stands occurwithin chaparral and coastal sage scrub (Esser1993). Walnut usually occupies mesic areas(i.e., riparian corridors, floodplains, andnorth-facing slopes) and prefers soils with ahigh clay content.
Figure 2.26. Southern California black walnutwoodland at California State Polytechnic University,Pomona. JANET NICKERMAN
Walnut woodlands are considered a de-clining plant community due to habitat losson private lands and low representation onpublic lands. Small populations are located onthe Angeles, San Bernardino, and Los Padresnational forests but quantitative data is avail-able only for the Los Padres National Forest.This data is based on Weislander maps devel-oped in the 1930s and probably representrough acreage estimates (Weislander 1935). Abetter determination of the current distribu-tion of this community is needed. Of the23,569 acres mapped in southern California,only 12 percent are located on public lands.
The great majority of walnut woodlandsare found in urban interface areas.Devegetation of private lands for developmentappears to be the primary threat to this com-munity. The tree has high horticulturalpotential, however, sometimes being incorpo-rated into urban forestry projects, and privatelandowners are being encouraged to retainthese woodlands as part of their landscaping.
Lack of sufficient regeneration is anotherproblem observed in some walnut woodlands.It is unclear whether the regeneration prob-lem is caused by livestock grazing, invasion ofnon-native annual grasses, seedling predation,
Cuyamaca Cypress GrovesIn the strict sense, Cuyamaca cypress
(Cupressus stephensonii) is known only fromthe Cuyamaca Mountains of San DiegoCounty and is the most narrowly distributedcypress in California. Some taxonomists be-lieve, however, that the tree is really an Arizonacypress variant (C. arizonica ssp. arizonica).This variant also occurs in the southern SierraJuarez east of Santa Catarina (R. Minnich, UCRiverside, in litt. 1998). In this senseCuyamaca cypress may be part of a larger spe-cies range that includes occurrences in Arizona,neighboring Sonora, and the Sierra Juarez.
Cuyamaca cypress forms several groves inthe Cuyamaca Peak/King Creek area in themountains of San Diego County (fig. 2.27).The groves represent a single population thatoccurs naturally over an estimated 230 acreson both the Cleveland National Forest andCuyamaca Rancho State Park (Winter 1994).In 1991 the Cleveland National Forest estab-lished the King Creek Research Natural Areato protect the cypress and its habitat. An ap-parently introduced population occurs in theAgua Tibia Wilderness near Palomar Moun-tain.
or disease, and it may prove to be a combina-tion of factors. Intensive livestock grazing inwalnut woodlands has been shown under cer-tain conditions to lower the survival rates ofwalnut seedlings by direct herbivory and bythe introduction of non-native taxa into theunderstory (Esser 1993). Conversion from anative perennial grass understory to one domi-nated by non-native annual grasses is believedto be a primary cause of low regeneration inwalnut woodlands much the same way it hasaffected oak woodlands (L. Merrill, San Ber-nardino NF, in litt.). A walnut woodland atHopper Mountain on the Los Padres NationalForest contains a large amount of Avena butvery little if any walnut seedlings.
The effects of existing fire regimes on wal-nut are poorly understood. The variety istop-killed by most fires but reproduces veg-etatively from the root crown and trunk afterburning (Esser 1993).
46
Like all native cypress in California,Cuyamaca is adapted to fire and produces se-rotinous or closed cones at maturity (Zedler1986). These cones require the intense heatgenerated by fire to open and disperse their
The tree usually grows in gabbro-derivedclay soils, on steep slopes along drainages. Itcan be dominant in the canopy or co-domi-nant with Coulter pine. Groves are typicallysurrounded by chaparral vegetation composedof chamise, manzanita, and scrub oak (fig.2.28). Two other rare plants, Dunn’s mariposalily (Calochortus dunnii) and Orcutt’s brodiaea(Brodiaea orcuttii), are found with Cuyamacacypress.
Figure 2.27. The distribution of gabbro soils, Cuyamaca cypress, and Tecate cypress in southern California.
seed as well as to prepare the soil for enhance-ment of germination. While periodic fires aretherefore necessary for regeneration, short fire-return intervals (e.g., less than every forty years)appear to gradually decrease stand densities bypreventing trees from reaching maturity andproducing seed (Winter 1994). The species hasrelatively thin, exfoliating bark that provideslittle protection from fire and is usually killedin wildfire events (Sullivan 1993b). Since treestypically reach maturity and begin to produceviable seed at approximately forty years, a fire-free interval of greater than forty years isneeded to maintain the seed pool/bank.
47
Chapter 2
Figure 2.28. Cuyamaca cypress and chaparral at KingCreek, Cleveland National Forest. These young treesgerminated after the 1970 Boulder Fire. MOZE MOSSAY
R. Minnich, UC Riverside, in litt. 1998).Usually found on mesic east- or north-fac-
ing slopes, Tecate cypress grows in alkaline,clay soils derived from ultramafic gabbroicrocks or metavolcanics (Zedler 1981)(fig.2.29). The tree was once more widespread butis now restricted to these unusual soils whereit lacks competition (Schoenherr 1992). LikeCuyamaca cypress, Tecate can be the definingcomponent of southern interior cypress for-est—a dense, fire-maintained low forest thatforms even-aged stands surrounded by chap-arral (Esser 1994a). Ceanothus, scrub oak, andchamise species are commonly found withTecate cypress, and the trees may also beviewed as a phase of chaparral vegetation(Zedler 1981).
Tecate cypress is strongly influenced byfire; seeds remain in the cones until fire causesthem to be dispersed and the trees themselvesare killed. Environmental conditions presentafter fire induce the seeds to germinate andre-establish the population. Despite this ad-aptation to fire, the species is vulnerable toeither excessively short or long fire-return in-tervals (Zedler 1981). Under currentconditions, overly frequent fire is the muchgreater threat. Tecate cypress trees begin toproduce cones after about ten years but takeabout fifty years to reach maximum cone pro-duction (Zedler 1977). If they reburn atintervals less than fifty years, reduced amountsof viable seed for regeneration would be ex-pected.
Cuyamaca cypress is an increasingly rarespecies within the assessment area. The Cleve-land National Forest has developed a speciesmanagement guide that summarizes ap-proaches to fire management and providesguidelines for the use of fire in enhancing cy-press stands on the forest (Winter 1994).
at elevations as low as 65 feet in Baja Califor-nia, Mexico, and up to 4,200 feet in the SanDiego and Santa Ana mountains (J. Gibson,San Diego Natural History Museum, pers.comm.). Its distribution is centered in Baja;however, some significant colonies are foundnorth of the border. A 50-acre grove on GuatayMountain in San Diego County and a 960-acre occurrence in the Sierra Peak/CoalCanyon area of the northern Santa Ana Moun-tains are located in the assessment area (fig.2.27). Groves in the Sierra Peak/Coal Can-yon area represent the northern limit of Tecatecypress distribution and its only OrangeCounty locality (White 1990). The largeststand of Tecate cypress in California (over5,000 acres) is south of the assessment area atOtay Mountain along the border with Mexico.Most of that occurrence is situated on landmanaged by the BLM. Numerous groves ofTecate cypress occur on the Mexico side ofOtay and Tecate peaks and in the coastalmountains of Baja California, extending about150 miles down the peninsula (Esser 1994a;
Eighty-five percent of Tecate cypresswithin the United States is located on publiclands yet the species is becoming increasinglyrare in these areas (K. Winter, Cleveland NF,unpubl. notes). Reduced stand densities areattributed mainly to increases in fire frequency.Data collected at both Tecate Peak and OtayMountain suggests that some of the grovesthere are diminishing in size. Using fire his-tory records, ring counts, and aerialphotographs, Paul Zedler was able to deter-mine the burn intervals at Tecate Peak fromapproximately 1800 through 1975, and atOtay Mountain from 1943 to 1976 (Zedler
48
A potential threat to gabbro habitat onnational forest system lands is the construc-tion of communication sites on mountaintops.Impacts to the habitat in other areas are largelyunknown. Strip mining of gabbro-derived claydeposits has occurred on private lands in thenorthern and eastern Santa Ana Mountains(Esser 1994a) and there is potential for in-creased mining to occur.
Montane MeadowsMontane meadows are found throughout
the assessment area, typically at elevationsabove 3,200 feet, and are represented on all
Figure 2.29. Mature Tecate cypress on OtayMountain, San Diego County. MILAN MITROVICH
(Mitoura thornei) are found exclusively withTecate cypress; however, the butterflies haveonly been observed in the grove on OtayMountain, outside the assessment area(Murphy 1990).
Gabbro OutcropsGabbroic rock exposures are found in the
foothills and mountains of San Diego Countyand the Santa Ana Mountains (fig. 2.27). Inthe San Diego region the substrate is knownfrom Cuyamaca, Guatay, McGinty, Potrero,Viejas, Poser, Los Pinos, Corte Madera, andIron mountains (Beauchamp 1986). An esti-mated 81,680 acres of gabbro-derived soilsoccur in southern California. Forty-one per-cent of those acres are found on public lands,most within the Cleveland National Forest.
Commonly called gabbro, the igneousrock is highly erodable and weathers into adark reddish, iron- and magnesium-rich soil(Schoenherr 1992)(fig. 2.30). The soil is some-times characterized as a poorly draining clay.Soil series formed from gabbro include LasPosas, Boomer, and Auld. They form ecologi-cal islands within more common substrates,such as granodiorite, and support unique plantcommunities including Cuyamaca and Tecatecypress groves (Gordon and White 1994).Several herbaceous plants are also endemic togabbro-derived soils, including two federallylisted species: San Diego thorn-mint(Acanthomintha ilicifolia) and Mexicanflannelbush.
1981). Sampling after the most recent (i.e.,1975 and 1976) fires showed that stands atleast fifty-two years old at the time of a fireproduced a greater number of seedlings perpre-burn tree, and that these stands reestab-lished at densities several times higher thanpre-fire densities (Zedler 1981). Conversely,stands thirty-three years old or younger at thetime of a fire established fewer seedlings thanthere were mature trees before the fire and ex-perienced significant decreases in standdensities.
Mining activities have also adversely af-fected Tecate cypress in the assessment area.Strip mining of underlying clay deposits de-stroyed some groves on private lands in theSierra Peak/Coal Canyon area of the Santa AnaMountains (Esser 1994a).
A species management guide for Tecatecypress was developed by the Cleveland Na-tional Forest that summarizes approaches tofire management and provides guidelines forthe use of fire in enhancing cypress stands onthe forest (Winter 1991a). The Guatay Moun-tain occurrence is proposed for designation asa Research Natural Area (RNA). An estimated64,000 trees occur at this site (Winter 1991a).A large portion of the Coal Canyon popula-tion (540 acres) was recently purchased by theCDFG and designated as an ecological reserve.
Two federally listed plants, Braunton’smilk-vetch (Astragalus brauntonii) and Mexi-can flannelbush (Fremontodendronmexicanum), are found with Tecate cypress.Larvae of the rare Thorn’s hairstreak butterfly
49
Chapter 2
Figure 2.30. Rocky gabbro soil and chaparral atKing Creek, Cleveland National Forest. The soil isrich in iron and recognized by its reddish color. MOZE
MOSSAY
four of the southern California national for-ests (fig. 2.31) (fig 2.32). The habitat typecovers an estimated 55,446 acres in southernCalifornia, 38 percent (21,070 acres) occur-ring on public lands.
Meadows can be characterized as wet, dry,or alkaline but are usually mesic, even in latesummer. Due to rainfall patterns they tend tooccur at lower elevations in the northern partsof California and shift to higher elevations inthe southern areas of the state (Holland 1986).Two physical conditions characterize mead-ows: 1) a shallow water table usually withintwo feet of the soil surface in mid-summer and2) surface soil material that is fine-textured(i.e., a clay) and richly organic (Wood 1975).Meadow soils are poorly draining relative tothe coarser soils of adjacent forest vegetation(Holland 1986).
Meadows tend to form where there aregentle gradients and relatively impervious bed-rock occurring in combination withappropriately sized upstream drainage basins.Where basins are large and produce high vol-umes of water, fine soil materials are washedaway, preventing the establishment of meadowhabitat. Stable meadows are those with shal-low slopes and smaller drainage basins wherefine materials are allowed to accumulate.Meadows that occur narrowly along streamsand creeks are referred to as “stringer mead-ows.” Meadows often form on or in closeproximity to fault zones. The availability ofsubsurface waters may be locally increased bythese subterranean impoundments (H. Gor-don, Remote Sensing Lab, in litt. 1998).
A mix of hardwood and conifer speciestypically encompasses meadows at lower el-evations. At higher elevations the surroundingforest shifts to mixed conifer and fir species.Jeffrey pine, white fir, incense-cedar, and blackoak are frequent components of surroundingvegetation in the mountains of San DiegoCounty (Winter 1991b). Montane meadowsare dominated floristically by sedges andrushes, with perennial herbs and grasses alsowell represented. Four federally listed plants,San Bernardino blue grass (Poa atropurpurea),bird-footed checkerbloom (Sidalcea pedata),slender-petaled mustard (Thelypodiumstenopetalum), and California dandelion(Taraxacum californicum), are found inmeadow habitat in the San Bernardino Moun-tains. The San Bernardino blue grass alsooccurs in montane meadows within San Di-ego County.
A survey of sixty-two meadows on theCleveland, San Bernardino, and Angeles na-tional forests and three state parks wasconducted in 1994 and 1995 (H. Gordon, Re-mote Sensing Lab, unpubl.data). Some of themeadows sampled are shown in table 2.17.
The largest meadows in the assessmentarea are found in the mountains of San DiegoCounty, but the majority of these are locatedon private lands (e.g., Cuyamaca, Mendenhall,French, and Dyche meadows). Other expansive
50
Figure 2.31. The distribution of montane meadows in southern California.
meadow systems are found in the San JacintoMountains, with the largest located in Gar-ner Valley. There are many meadows in theSan Bernardino Mountains, but most are smallin size. The San Gabriel Mountains contain veryfew meadows due to their steep topography, al-though Big Pines Meadow is significant as theprimary location for the San Gabriel Mountainsblue butterfly (Plejebus saepiolus aureolus). In theCastaic region, Knapp Ranch Meadow is esti-mated to cover almost two hundred acres.
Montane meadows on the Los PadresNational Forest include Toad Springs, Thorn,and Chula Vista meadows, Yellow Jacket Creek(a series of stringer meadows), and several un-
named meadows near Lockwood, Grade, andCuddy valleys, Mount Abel, and the SanEmigdio Mesa area (J. O’Hare, Angeles NF,in litt. 1998).
All meadow habitats are sensitive to ac-tivities and disturbances that affect stabilityof the surface soil, especially during the win-ter and spring when the ground is mostsaturated. Meadow systems, particularly thoseon steeper slopes, can develop gullies in re-sponse to disturbance. The best examples ofthis are associated with road and trail systemsthat increase the amount of runoff a meadowreceives and cause soil erosion. Eroded areasconvey water at a higher rate, eventually lead-ing to the formation of gullies, which in turn
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Chapter 2
Figure 2.32. Montane meadow habitat at Bluff Lake,adjacent to the San Bernardino National Forest. Anendangered plant, the bird-footed checkerbloom, isfound here. LYNN LOZIER
channel water away from the meadow, effec-tively lowering the water table and removingincreasing amounts of topsoil (J. O’Hare,Angeles NF, in litt. 1998; M. Bearmar, Cleve-land NF, pers. comm.).
When the water table of a meadow is low-ered, it allows for the steady encroachment andestablishment of nonmeadow flora. Runofffrom road and trail systems appears to be oneof the greatest impacts to meadow habitatswithin the assessment area. Recurrent tram-pling by livestock, vehicles, or people can alsointroduce soil erosion and cause gullying. Overtime gully systems may become stabilized andform riparian habitat, much like what has oc-curred at Knapp Ranch on the AngelesNational Forest and Thorne Meadow on theLos Padres National Forest (J. O’Hare, Ange-les NF, in litt. 1998). The plains appear as distinct open patches
within forest and woodland vegetation oftendominated by Jeffrey pine, pinyon, and juni-per species (fig. 2.34). Remnants of a hugeice-age lake bottom (Krantz 1983), the plainsare part of the Mohave crustal block upliftedduring Quaternary time (Derby and Wilson1979). They are treeless, deep clay depositsthat support a rare assemblage of plants remi-niscent of an alpine flora. This flora consistsof small cushion-forming plants, tiny annu-als, grasses, and succulents. The plants are allwell spaced, low growing, and sun tolerant,yet exact floral composition varies betweensites. The substrate consists of clay soil (up to
Many montane meadows on national for-est system lands have historically beenimpacted by the overgrazing of livestock(Krantz 1983; M. Borchert, Los Padres NF,pers. comm; J. O’Hare, Angeles NF, pers.comm.). Excessive grazing is believed to shiftfloral composition from native perennials tonon-native annual species (Winter 1991b) andthe current trend on national forest systemlands has been to reduce the number of cattlein these areas or remove them completely fromespecially sensitive locations. However, the in-vasion of alien taxa appears to be a greaterproblem in lower elevation meadows ratherthan at higher elevations, where the habitat
seems to be in better condition overall (R.Minnich, UC Riverside, in litt. 1998).
The Cleveland National Forest has devel-oped a habitat management guide for foursensitive plants that grow in riparian montanemeadows: Cuyamaca larkspur (Delphiniumhesperium ssp. cuyamacae), lemon lily (Liliumparryi), Parish’s meadowfoam (Limnanthes gra-cilis var. parishi) and San Bernardino blue grass(Winter 1991b).
Pebble PlainsPebble plains have a very limited distribu-
tion in the northeastern San BernardinoMountains, occurring between elevations of6,000 and 7,500 feet. They are found onlywithin a 92-square-mile area near the city ofBig Bear, on the San Bernardino NationalForest and on adjacent private lands (fig 2.33)(Neel and Barrows 1990). Some well-knownsites include the Big Bear Lake complex, theSawmill complex, Gold Mountain, NorthBaldwin Lake, Arrastre Flat/Union Flat,Holcomb Valley, south Baldwin Ridge/ErwinLake, Onyx Ridge/Broom Flat, and CoxeyMeadow. Three hundred and seventy-nineacres of pebble plain habitat are mapped inour GIS database, 60 percent located on pub-lic lands. The Pebble Plain HabitatManagement Guide and Action Plan cites 546acres of pebble plain habitat with 94 percentoccurring on public lands (Neel and Barrows1990).
Table 2.17. A partial list of montane meadows on the Cleveland, San Bernardino, and Angeles nationalforests and Palomar Mountain State Park. The assessment of meadow condition is based on notes taken by H.Gordon during her field surveys in 1994 and 1995. Acreages reported are visual estimates.
Meadow Name Water Source Date of Assessment of Meadow Sampling Characteristics and Condition
Cleveland NFGuatay runoff from Guatay Mtn. 5/95 upper area type converted?, drainage
channel, structures; 10-50 acres
Laguna Big and Little Laguna 7/95 some erosion in the channeled area oflakes, Boiling Springs, the check dam, Prado area has cattle;Escondido, Chico, and 500-600 acresLos Rasalies ravines,Agua Dulce Creek
Lost Valley Caliente Creek, spring 5/95 horses, portion of meadow in privateownership, dispersed camping; 50-100acres
Love Valley upland runoff 7/94 50-100 acres
Mendenhall Iron Springs Creek 6/95 historic and recent cattle grazing; 100-200 acres
Organ Valley spring-fed 6/95 RNA for Engelmann oak; 5-10 acres
Roberts Ranch upland runoff 5/95 gullies caused by runoff from I-8, cattle,recent acquisition; 100-200 acres
Tenaja upland runoff, springs 5/95 type conversion from chaparral? 100-200 acres
San Bernardino NFBaldy Mountain unknown 7/95 jeep trail, horse-holding structures,
cattle, adjacent to fire break; 50-100acres
Big Meadow Santa Ana River 8/95 lower portion of meadow affected byupstream gullying, the encroachment ofGreat Basin sagebrush, and non-nativespecies; 50-100 acres
Broom Flat Arrastre Creek, runoff 7/95 cattle; 50-100 acres
Coxey springs, Coxey Creek 8/95 non-native species in northern area ofmeadow; 10-50 acres
Garner Valley South Fork of San 7/95 some soil erosion, cattle; >300 acresJacinto River
Holcomb Valley Holcomb and Caribou 8/95 historic gold mining and ranching in thecreeks Belleville area; 50-100 acres
South Fork South Fork of Santa 9/95 irrigation ditch in upper meadow area;Ana River 10-50 acres
Tahquitz Tahquitz Creek 9/95 Jeffrey pine encroaching on lowermeadow, trail; 10-50 acres
Angeles NF
Big Pines seasonal Mescal Creek 6/95 wet meadow easily accessible, retreatingsystem due to expansion of Mountain High Ski
area parking lots, presence of SanGabriel Mtns. blue butterfly; <5 acres
Brown’s Flat overland flow 6/95 in the San Dimas Experimental Forest;50-100 acres
Knapp Ranch seasonal Castaic Crk system 5/95 100-200 acresPalomar State ParkLower French French Creek 5/95 some channelization, adjacent forest
burned
Upper Doane Doane Creek 6/95 not grazed regularly since 1940s, someerosion, small channel; 50-100 acres
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Chapter 2
53 percent) mixed with quartzite pebbles andgravel that are continually pushed to the sur-face through frost action (Holland 1986; Neeland Barrows 1990). The combination of claysoil, frost heaving, extreme annual and dailytemperature fluctuations, high light intensity,and dessicating winds is thought to preventthe establishment of tree species onto theplains (Derby and Wilson 1979). Three fed-erally listed plants, Big Bear Valley sandwort(Arenaria ursina), ash-gray Indian paintbrush(Castilleja cinerea), and southern mountainbuckwheat (Eriogonum kennedyi var.austromontanum), are found on pebble plains.
Figure 2.33. Occurrences of pebble plains and carbonate outcrops in the eastern San Bernardino Mountains.
An estimated 150 acres of pebble plainhabitat are believed to have been lost by cre-
ation of the Big Bear Lake reservoir in the1800s. More recently the habitat has declinedin amount and quality primarily from vehicleactivity on the sites (Neel and Barrows 1990).Some pebble plains have been completelydevegetated (e.g., upper Sugarloaf ). The habi-tat is especially vulnerable to damage fromvehicles when the ground is saturated. Deepruts are created in the soil that directly affectthe vegetation and alter the surface hydrologyof the plains.
The Pebble Plain Habitat ManagementGuide and Action Plan was developed by theSan Bernardino National Forest to providemanagement direction for long-term conser-vation of pebble plains and the rare plants
54
assocated with them. Closure of unauthorizedvehicle routes through pebble plain habitat (in-cluding walk-throughs that discouragemotorcycle access and barriers to prevent ve-hicle access), signage, increased patrol, mineralwithdrawal, habitat acquisition, removal ofnon-native grasses, and public education areactions being taken to protect and enhancethe habitat. Conserving pebble plain habitatover a broad geographic range, reducingfragmention, and encouraging compatible usesare Forest Service goals for this habitat.
Limestone/Carbonate OutcropsCarbonate outcrops are found along the
desert-facing slopes of the San BernardinoMountains. Located mainly within the SanBernardino National Forest, these soil depos-its extend for approximately twenty milesalong an east-west axis and occupy an esti-mated 21,000 acres. Over 18,000 acres of theseunique soils are within the assessment area, ofwhich 87 percent are on public lands (fig.2.33). Disjunct outcrops occur just south ofSugarlump Ridge and to the east as far as theSawtooth Hills (USFWS 1997b). The U.S.Fish and Wildlife Service Draft Recovery Planreports a higher amount of total carbonatehabitat (32,620 acres) though subsurface de-posits may account for the additional acres(USFWS 1997b).
Figure 2.35. Carbonate habitat north of HolcombValley in the San Bernardino Mountains. A low-growing plant, the endangered cushenburybuckwheat, can be seen in the foreground. TIM KRANTZ
High-grade carbonate deposits in the SanBernardino Mountains are mined for com-mercial use; the carbonate in these mountainsis one of just three high-quality deposits inthe western United States (Krantz 1983,1990). Limestone is used in a number of com-mercial applications and almost all of thehabitat on public land is under mining claims.Mining activities such as the direct removalof soil, road development, and dumping ofoverburden rock, have led to an overall de-cline in the amount and quality of carbonatehabitat. Plant communitites associated withthis habitat are slow to recover from distur-bance due to the low productivity, thin soils,and very dry climate on the desert side of thesemountains (Rowlands 1980).
The high levels of ground disturbance as-sociated with mining, the potential foradditional claims to become active, and in-sufficient protection mechanisms necessitated
Figure 2.34. Pebble plain habitat at Gold Mountain,San Bernardino National Forest. Plants in this habitattype are diminutive and alpine-like. Despite theirappearance, pebble plains have high floral diversity.MAILE NEEL
Carbonate is named for its primary con-stituent, calcium carbonate. The substrate isan alkaline, sedimentary rock type that weath-ers into limestone and dolomite soils. Anumber of plants are endemic to these car-bonate soils (see carbonate plant group,chapter 5). On a broader scale, carbonate out-crops support desert montane plantcommunities such as blackbush scrub, pinyon-juniper woodlands, Jeffrey pine-westernjuniper woodlands, and Joshua tree woodlands(USFWS 1997b) (fig. 2.35).
55
Chapter 2the federal listing in 1994 of five rare plantsendemic to carbonate (Neel 1997). This lawcreated a rare situation where two very promi-nent laws (the 1872 Mining Law and the 1973Endangered Species Act) appear to conflictwith one another.
To resolve this issue, a collaborative efforthas been initiated among the San BernardinoNational Forest, the Bureau of Land Manage-ment, the U.S. Fish and Wildlife Service, mineoperators, researchers, and other affected par-ties, to design a reserve system for these plantsand their habitat (G. Zimmerman, San Ber-nardino NF, in litt. 1998). The CarbonateEndemic Plant Conservation Strategy is be-ing designed to incorporate many largeoccurrences of the five listed plants over a widerange of habitat mosaics throughout their geo-graphic ranges. Buffers to minimize conflictsand to ensure defensible areas, connectionsbetween populations and habitats, and inclu-sion of sites that contain more than one listedspecies are other important elements beingconsidered in the reserve design. Genetic re-search through patterns of isozyme variation(Neel 1997), results of soil sampling, and adetailed vegetation classification combinedwith field studies of individual plant occur-rences are being completed and will provideinformation necessary for the reserve design.GIS coverages of plant locations, carbonaterock locations, proposed and approved futuremining activities, land use conflicts, and otherresource values have been developed in theConservation Study for Five Carbonate PlantSpecies: a study of land use conflict in the SanBernardino National Forest (USDA Forest Ser-vice 1996).
Serpentine OutcropsSerpentinite rock outcrops occur within
the assessment area in the Santa Lucia Ranges,the southern Los Padres region, and at onelocality in the Santa Ana Mountains. Withinthe boundaries of the Los Padres Natonal For-est are an estimated 31,470 acres ofserpentinite-derived soil (fig. 2.36).
This soil, commonly called serpentine, isrecognized by its waxy texture and colors that
range from green to blue to red. Generally highin magnesium (consisting mainly of hydratedmagnesium silicate) and low in calcium, ni-trogen, and phosphorous, the soil is consideredimpoverished and supports only those plantsadapted to or tolerant of its unique chemis-try. It contains varying amounts of heavymetals (e.g., cobalt, nickel, and iron) that con-tribute to its color (J. O’Hare, Angeles NF,pers. comm.).
In its favor, serpentine often has a higherwater-holding capacity than adjacent soils (i.e.,it forms clay soils). Grassland, chaparral, oakwoodland, and conifer forest may all form ona serpentine substrate, but species richness anddensity is always much lower than on adja-cent nonserpentine soils (Kruckeberg 1984).Extreme serpentine habitats are referred to as“barrens” because they support little or novegetation. Less toxic sites can support up to215 species and varieties of plants and at leastnine species and subspecies of butterflies(Schoenherr 1992). Sargent cypress andknobcone pine are reliable indicators of a ser-pentine soil. Twelve of the plant speciesaddressed in this assessment are indicators ofor endemic to serpentine soils. Of these, ten areclassified by the regional forester as forest servicesensitive on the Los Padres National Forest (seeserpentine plant group in chapter 5).
The Cachuma Saddle area and FigueroaMountain, both in the San Rafael Range, con-tain serpentine chaparral and woodland,including groves of Sargent cypress. Serpen-tine woodland and Sargent cypress occur againat Cuesta Pass and West Cuesta Ridge in thesouthern Santa Lucia Range. Further north,the Chew’s Ridge area in the Santa LuciaRanges contains good examples of serpentinegrassland and woodland. Serpentine grasslandis also found in the Pine Ridge area of the SantaLucia Ranges (Kruckeberg 1984).
Serpentine is an indicator of economicmetals; quicksilver (mercury), chromium,nickel, magnesite, asbestos, talc, soapstone,and jadeite are all found in association withserpentine and other ultramafic outcrops. Anumber of historic and active mines occur in
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Three substantial groves occur on the for-est at Zaca and Alder peaks and in the CuestaRidge Botanical Area (fig. 2.38). At least sixadditional sites are also located in the SantaLucia Ranges (D. Wilken, Santa BarbaraBotanic Garden, in litt. 1998).The grove atCuesta Ridge in the southern Santa Lucias isthe southernmost large occurrence and one ofseveral isolated groves ranging from northernMendocino County south to Zaca Peak in
Figure 2.36. The distribution of serpentine outcrops on the Los Padres National Forest.
the Santa Lucia Ranges and potential existsfor mining activities to adversely impact ser-pentine habitat on the forest (Kruckeberg1984).
are scattered within the assessment area in theSanta Lucia Ranges and southern Los Padresregion. Groves are distributed from 650 to3,300 feet elevation. The species is consideredthe most wide-ranging cypress in California(fig. 2.37). Based on Clare Hardham’s map-ping effort, an estimated 1,585 acres of Sargentcypress habitat occur in central and southern
California, with 74 percent located on publiclands (Hardham 1962). A small amount isfound on U.S. Army Fort Hunter LiggettMilitary Reservation and 880 acres are re-ported on the Los Padres National Forest (LosPadres NF 1988a).
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Chapter 2
Figure 2.37. The distribution of Santa Lucia fir forest and Sargent cypress groves in central and southernCalifornia.
Santa Barbara County. The Zaca Peak site, lo-cated near the San Rafael Wilderness Area, ismuch smaller than the occurrence at CuestaRidge (Jenkins 1981). In the Santa LuciaRanges, the majority of groves are locatedalong the main ridgeline at about 2,500 feet.The tree may be more prevalent at these sitesdue to heavy fog occurrence (Hardham 1962).Sargent cypress is also located along a ridgeformed by the King City Fault near Brysonand at lower elevations in the Los Burros Creekdrainage.
Sargent cypress is an indicator of serpen-tine soils and tends to occur with othersensitive plant species (Los Padres NF 1988a).
Factors other than soil affect the distributionof Sargent cypress, however, as it occupies lessthan three percent of serpentine habitat on theforest. The tree grows on rocky slopes, ridges,and raised stream benches and terraces (Saw-yer and Keeler-Wolf 1995). Throughout mostof its range Sargent cypress occurs with graypine, Coulter pine, scrub oak, leather oak, andbuck brush (Johnston 1994). It also frequentlygrows with California bay, interior live oak,and knobcone pine. Muir’s hairstreak butter-fly is strongly allied with Sargent cypress.
Like other cypress, Sargent is adapted toand dependent on fire for seed dispersal andenhancement of germination. Fires that are
58
Occurrences range from a low point atBig Sur Gorge to the top of Cone Peak butgreater than half of the fir’s distribution isabove 3,200 feet (Talley 1974). The south-ernmost stands occur at lower elevations inSan Luis Obispo County. These stands arefound along coastal drainages sometimesadjacent to redwood (Sequoia sempervirens).Occupied drainages include MarmolejoCreek, Jackson Creek, the Big Sur River, thewest and main forks of Limekiln Creek,Hare Canyon, and Villa Creek. The speciesis also found along north- and east-flowingdrainages including the Carmel River, MillerFork, Anastasia Canyon, Church Creek, ZigZag Creek, Higgins Creek, the Arroyo SecoRiver, the San Antonio River, the NegroFork of Nacimiento River, and San MiguelCreek.
Based on physical characteristics of thesites it occupies (rocky areas with low fuelloads), Santa Lucia fir is generally regarded asintolerant of fire, yet some mature stands havesurvived wildland fires (J. Kwasny, Los PadresNF, pers. comm.). Talley looked at the firehistory of Santa Lucia fir and determined thatthere were few differences between past andpresent fire intensities within stands, despitechanging fire regimes in California overall. Firesuppression activities such as fire lines and
scale map of all known Santa Lucia fir stands(Talley 1974). Based on this map there are anestimated 7,576 acres of Santa Lucia fir for-est, with 95 percent located on public lands.The Los Padres Forest Plan however, cites1,400 acres of Santa Lucia fir within the for-est boundary (Los Padres NF 1988).
Stands occur in relatively inaccessible ar-eas: on steep north- or east-facing slopes, alongridges, in canyon bottoms, and on raisedstream benches and terraces (fig. 2.39) (Saw-yer and Keeler-Wolf 1995). The tree may bedominant in stands or co-dominant with can-yon live oak. At lower elevations it occupiesthe same habitats as coast live oak, Pacificmadrone, and coast redwood. At higher el-evations it grows with tan oak, interior liveoak, and incense-cedar (Johnston 1994).
Figure 2.38. Sargent cypress and chaparral growingon serpentine soil at Cuesta Ridge Botanical Area,Los Padres National Forest. MALCOLM MCLEOD
too frequent, however, prevent adequate seedproduction and can extirpate entire groves(Esser 1994b). South of an existing WaterdogCreek grove, a cypress “swamp” is believed tohave been extirpated by fires in 1953 and 1960(Hardham 1962). The tree has a low-branch-ing habit that makes it susceptible to crownfire and is often killed in wildfires. Requiredfire-free time intervals are not well defined forthe species but might be consistent with othercypress in California (Esser 1994b).
Sargent cypress is generally not considereda rare tree and has no legal status. However,because it is localized on serpentine soil andbecause some groves, particularly on theMonterey Ranger District, have been reducedin size by short fire-return intervals, Sargentcypress communities are considered rare onforest system lands (M. Borchert, Los PadresNF, pers. comm.).
Santa Lucia Fir ForestSanta Lucia fir (Abies bracteata), also
known as bristlecone fir, is found in the north-ern Santa Lucia Mountains of MontereyCounty. The tree is narrowly distributed inan area about thirteen miles wide and fifty-five miles long in the Ventana Wildernes areaof the Los Padres National Forest and a por-tion of U.S. Army Fort Hunter Liggett,bordering the forest on the east (fig.2.37)(Schoenherr 1992). As part of hismaster’s thesis, Steve Talley produced a coarse-
59
Chapter 2fuelbreaks are not currently allowed in standson the Los Padres National Forest. Fire is notprevented from burning through stands noris it directed toward stands.
Several naturalists, beginning with Sargentin 1898, have recognized Santa Lucia fir as aspecies at risk due to its narrow endemism andsusceptibility to cone parasites (Talley 1974).Occurrences of Santa Lucia fir appear stableat this time; however, a recently recognizedthreat is the invasion of non-native species intothe understory. The rhizomatous shrub Frenchbroom (Genista monspessulana) is particularlyinvasive and difficult to eradicate once estab-lished. It directly competes with seedlings ofSanta Lucia fir and other native understoryspecies (J. Kwasny, Los Padres NF, pers.comm.)
Figure 2.39. A stand of Santa Lucia fir at Cone Peak,Monterey Ranger District, Los Padres National Forest.JEFF KWASNY
Disjunct (Locally Rare)Communities
Two disjunct plant communities wereidentified in the assessment area. These com-munities are relatively common in other areas,but are rare or highly localized within the as-sessment area. They are briefly describedbelow.
Aspen GrovesQuaking aspen (Populus tremuloides) is a
wide-ranging tree in North America, but itsdistribution is patchy in the Californias. It iswidespread in the Sierra Nevada and there aresubstantial stands in the White Mountains andin Baja California’s Sierra San Pedro Martir.However, aspen is essentially absent in thesouthern California mountains with the ex-ception of two small groves in the SanBernardino Mountains: one on Fish Creek inthe San Gorgonio Wilderness Area and theother on upper Arrastre Creek (Thorne 1977).These two occurrences combined cover lessthan fifty acres, all of which are located onnational forest system land. A third grove, re-portedly mapped in 1935 by D. Axelrod, maystill exist west of Lake Arrowhead (Jones1989). The groves are found on decomposedgranite at the bottom of canyons and on slopesalong creeks.
The Arrastre Creek aspen grove occursalong a seasonal watercourse. It is foundmainly with xeric plants (i.e., sagebrush scrub,pinyon, Jeffrey pine forest) and endures a drysummer climate. Aerial photographs from1972 and 1983 indicate that the grove is de-creasing in size (Jones 1989). The Fish Creekaspen grove also occurs along a drainage inwhat is otherwise a Jeffrey pine and subalpineforest. Beavers were introduced into the habi-tat and subsequently reduced this grove by anestimated 25 to 50 percent (Jones 1989).
Evidence indicates that the tree was oncemore common in the mountain ranges ofsouthern California and migrated into north-ern Baja during prehistoric times (Oberbauer1986). Aspen is a clonal organism and the SanBernardino Mountain populations were
60
Figure 2.40. Knobcone pine near Cuyama Grade,Los Padres National Forest. JANET NICKERMAN
analyzed and found to be almost geneticallyidentical to each other (Zona 1989).
Knobcone Pine StandsDisjunct stands of knobcone pine (Pinus
attenuata) occur naturally in the assessmentarea at just a few locations: in the northernSanta Lucia Range of Monterey County, inSan Luis Obispo County at Cuesta Pass, inthe western San Bernardino Mountains, andin the Santa Ana Mountains (Vogl et al. 1977).There are approximately 1,233 acres ofknobcone pine habitat mapped at these loca-tions, 85 percent of which is located on publiclands. The species is more common through-out northern California and also grows nearEnsenada, Mexico.
Knobcone pine has been reported fromsea level to over 5,500 feet, though stands usu-ally occupy a transitional zone between lowerchaparral/woodland and higher elevation co-nifer forest (Vogl et al. 1977). Talley andGriffin (1980) and Griffin (1982) report onthe fire ecology of knobcone pine in the north-ern Santa Lucia Range. Similar to Coulterpine, knobcone pine has serotinous cones andis dependent on fire for seed dispersal (Vogl1976).
In the San Bernardino Mountains, standsof knobcone pine cover approximately 990acres between City Creek and GovernmentCanyon. In the Santa Ana Mountains, smallstands of this pine occur in otherwise chapar-ral-dominated areas on the slopes of Sugarloaf,Pleasants, and Santiago peaks (Thorne 1977;F. Roberts, USFWS, pers. comm.). The standat Pleasants Peak grows on serpentine soils (EAEngineering, Science, and Technology 1995).Usually restricted to dry, rocky sites with shal-low soils, knobcone pine is typically associatedwith infertile substrates that limit competitionfrom other conifers (Holland 1986) (fig. 2.40).
