Chapter 4 The Sierra Nevada
pgs. 92-122
by The Mama's and the Papa's

 Biotic Zone

.   The distribution of communities in the Sierra Nevada is influenced by
elevation, latitude, rain-shadow effect, and slope effect.  Complex interactions of  living and nonliving factors provide a habitat

.   Nonliving (abiotic) factors of the environment are variations in light, heat, water and soil.

.   Biotic factors include all the organisms and their interactions.

.   Eastern slopes are drier than the west because of the rain-shadow effect. The result is that zones tend to occur at higher elevations, and cooler temperatures causing less evaporation making the water go farther.
.   The influence of temperature on evaporation is called slope effect. South facing slopes are hotter and drier.  Slope effect is more pronounced at lower elevations, and also toward the South because that is where the growing season is limited by summer drought.

Valley Grassland

.   Grassland is community associated with deep alluvial soils.  Sand and gravels thousands of feet thick have washed out of the mountains and lie in the valley.  Water percolates too deeply for the roots causing these plants to die each summer.

.    The savannah is mixture of trees and grasses, this area also has thinner soils and water is closer to top of the soil.

Foothill Woodland

.   Foothill woodland surrounds the Great Central Valley ( a.k.a. Oak Woodland) this is one Cal most widely distributed communities.  Woodland covers about 10 million acres. Two predominant trees in this belt Digger Pine and Blue Oak.

.   Other large oaks in the foothill woodland include Valley Oak, Interior Live Oak.  At scattered locals in the foothills are Redbuds.


.   Several kinds of scrub or shrub communities that go by the name of chaparral.

.   Chaparral is important component of the foothill community and includes many species such as Chamise, California Scrub Oak, a scrub form of Interior Live Oak and Flannel Bush.

Edaphic Communities

.   Edaphic communities occur where soil is the principal factor to which the community must adapt.

.   A total of 215 species and varieties of plants are restricted to (endemic on) serpentine soils in California.

.   Serpentine soils are high in magnesium and low in calcium, and they contain heavy metals such cobalt, nickel, and iron.  They are often clay-like and low in nutrients

Foothill Animals

.   The insects and animals of the foothill must be able to endure the long hot summers and cold winters.  The foothills have a great variety of insects and reptiles.

.   Niche partitioning - a concept that defines an ecological niche to the "space" in a particular ecosystem occupied by a species.  A niche refers to the role played by a particular species as it interacts with all the other species of an ecosystem.

.   Birds: The Foothill Woodland is home for a large variety of bird species for which oaks are important for food and shelter. Cavities in oak trees are homes for many animals such as owls and Gray Squirrels.  Woodpeckers, Western Bluebirds use smaller holes for homes.

.   Most birds in the foothills are omnivores. Probably the most important food in the foothill is the acorn.

.   Flying insects are an abundant food source, but mostly in the summer. The Black Phoebe is one of the year-round residents that rely on flying insects. In the summer however a number of migratory insect eaters appear on the scene in order to share the wealth of insects.

1.  Ground Squirrel (Spermophilus beecheyi)
2.  Western Gray Squirrel  (Sciurus grisseus)
3.  Red Tailed Hawks (Buteo jamaicensis)
4.  Badgers (Taxida taxus)
5.  Owl (Athene cunicularia)

Yellow Pine Forest 

(also called Transition Zone or Mixed Coniferous Forest of Lower Montane Forest).
 - Refers to the Ponderosa Pine (Pinus ponderosa) and the Jeffrey Pine (Pnius jeffreyi).
 -average precipitation for the forest...40 inches.
 -members of this forest are California Black Oak (Quercus kelloggii) and the Incense Cedar (Calocedrus decurrens).

Incense Cedar has flattened, scale like leaves arranged in branching chains.  It's color is bright green.  It's bark is reddish and fibrous.  Excellent for starting fires.

Ponderosa Pine has brownish yellow bark and it's needles occur in clusters of three and are yellow.  No odor.  Cones less than 5 inches long.  Cones prick.

Jeffrey Pine bark tend to consist of a series of narrow ridges and smells of vanilla or butterscotch.  Cones can be 10  inches long.  Cones do not prick  Located in high elevations in Rocky areas.  Also grows in serpentine soils at lower elevations.

Insects that effect the pines are:
1.  Bark Beetles (Scolytidae)
2.  Pine White (Neophasia menapia)  2 inches long, white with heavy black markings around the tips of the front wings.
3.  Ponderosa Moth (Coloradia ponderosa)  The adult is one of the silk moths (Saturniidae).  It is the larvae that do the damage. 

Washoe Pine (Pinus washoensis) is located in high elevations.  Large needles in cluster of three, the cone is intermediate in appearance.  Smaller cones that the Jeffrey but not prickly.

Quaking Aspen (Populus tremuloides) are highly dependent on abundant soil moisture.

White Fir (Abies concolor) ahs stiff, blunt needles distributed evenly along the stem.  Can be expensive Christmas trees.

Sugar Pine (Pinus lambertiana) is the tallest and largest of all the pines in the world.  Cones are usually  over foot long  and often reach 18 inches.  Needles are 3 to 4 inches long.  These trees occur at lower elevations than the other pines.  May exceed 500 years in age.

Douglas firs (Pseudotsuga menziesii) is an inexpensive Christmas tree.  Darker green and has long, hanging side branches. 

Giant Sequoias (Sequoiadendron giganteum) are moisture demanding.  The bark is resistant to fire.  Some trees live to be 2000 years old.  The largest living thing in the world. 

Fungus has infected the root system of the conifers in the Yosemite valley.  This disease is known as root rot.  A fungus that is a fire follower is the morel (Morchella angusticeps) a conical mushroom with deeply pitted cross veins between gray to black vertical ridges.  Mostly occurs where California Lilacs (Ceanothus) have been established.

Control burns were established to help the tree groves survive.  This reduced fuel buildup, burn White firs, kill root rot and simulate natural conditions. 

Giant Carpenter ants (Camponotus laevigatus) make nest in trees by hollowing them out which weakens the structure.  These trees effected were the White firs which had aphids in them.  These pests along with Spruce Budworms, Bark Beetles, fungi and Dwarf Mistletoe can be controlled by control burns. 

A long horned beetle (Phymatodes nitidus) helps cones release their seeds by producing larvae that chew into the cone which kills the cone.  The seeds are released and distributed along the ground where squirrels can eat them.  These seed are the beginnings of a redwood tree.

John Muir and the Sierra club has helped to preserve the trees in the Sierra's.

Manzanita (Arctostaphylos) grow in the Yellow pine forest.  It's name means "little apple".

Kit-kit-dizze (Chamaebatia foliolosa) is a member of the rose family (Rosaceae).  Also known as bear clover. 

Western Azalea (Rhododendron occidentale) grows in redwood groves. 

Chapter Summary &emdash; Chap. 4 (pp.92-122)
Chapter 4 is about the Sierra Nevada


"The distribution of communities in the Sierra Nevada (fig. 4.18) is influenced by elevation, latitude, rain-shadow, and slope effect. Complex interactions of living and nonliving factors provide an environment that is called the habitat. Among the nonliving (abiotic) factors of the environment are variations in light, heat, water and soil. The biotic factors include all the organisms and their interactions. A habitat therefore, is where organisms live." (p. 92).

Valley Grasslands

Introduced Mediterranean grasses and weeds are part of the grassland community associated with deep alluvial soil. From sand and gravel washed from mountains, these plants tend to die every summer because the water percolates too deeply to maintain root systems. Closer to the Great Central Valley, deep rooted Oak trees grow giving the area a "savannah" landscape.

Foothill Woodland

Also called Oak Woodland. Two predominant trees are Digger Pine, Pinus sabinana and Blue Oak, Quercus douglasii. In California there are 20 species of pines, 16 species of oak. Digger Pines are now commonly called Gray Pines, because of their gray-green foliage. They have long needles in clumps of three, large cones with hooks. Blue Oak have leaves about 3 inches long, seven lobes. The acorns are eaten by birds and mammals. Overfeeding has caused poor regenerating. This could cause Blue oaks to disappear. Valley Oak, Quercus lobata and Interior Live Oak, Quercus wislizenii have large greener leaves and 9 to 11 lobes.

Interior Live Oaks do not drop leaves in winter. As elevation rises Blue Oak, California Buckeye and Redbuds appear on north-facing slopes.


It is commonly called scrub or shrub communities. Chamise, Adenostoma Fasciculatum, California lilac, Ceanot hus spp., California Scrub Oak, Quercus berberidifolia. The Flannel Bush, Fremonto dendron californica.

Edaphic Communities

"Soil is the principal factor to which the communities must adapt."(p.100) Serpentine is the state rock; soil contains cobalt, nickel and iron, high in magnesium, low in calcium. Chamise is able to tolerate serpentine soils. Interior silk Tassel, Garrya congdonii, Scrub Oak, Leather Oak, Quercus durata, and Knobcone Pine, Pinus attenuata, tolerate serpentine soils.

There is limestone and marble in western Sierra. East side along Convict Creek, Desert Chaparral, Sagebrush scrub, riparian vegetation, manzanita, Arctostaphylos uva-ursi, a willow, Salixbrachycarpa, a sedge, Scripas rollandi, a lousewort, Scrophu lariacae.

Foothill animals include mammals, insects and reptiles.

Niche Partitioning

"A niche refers to the role played by a particular species as it interacts with all the other species of an ecosystem."(p.102) In the Sierra Nevada, niche partitioning occurs as the elevation increases.

Birds-Foothill Woodland

Great Horned Owls, Burrowing Owls, California Quail, Woodpeckers, Western Blue birds, White- breasted Nuthatch, Western King bird, Tyrannus verticals, Nighthawks, Chordeiles spp., swallows and swifts, the plain titmouse, Parus imornatus, and other gleaners. The food source is acorns, insects and berries.


California Ground Squirrel, Spermophilus beecheyi. "Their appetite for acorns coupled with their increase in numbers, is considered to be on of the contributing factors leading to the decline in the number of oak seedlings."(p. 106) Western Gray Squirrels, Sciurus griseus, typically a tree squirrel. Badgers, Taxiada taxus, prey upon ground squirrels.

Yellow Pine Forest

Formerly called Transition Zone, modern biologists also call it Mixed Coniferous Forest or Lower Montane Forest. Western Yellow Pine refers specifically to Ponderosa Pine, Pinus ponderosa, and also general use for related species, Jeffrey Pine, Pinus jeffreyi. Yellow Pine Forest occurs on both east and west slopes of Sierra Nevada. The forest also has California Black Oak, Quercus kelloggii, and Incense Cedar, Calocedrus decurrens. There are two subgroups, dry Yellow Pine Forest and moist Yellow Pine Forest. "At most elevation, the distinction between the two groups is as simple as the difference between north-facing and south-facing slopes. On the east side of the Sierra, dry Yellow Pine Forest prevails."(p. 108)

Black Oak is winter-deciduous. They can resprout after a fire. Ponderosa and Jeffery Pines can grow very large. "Gray Pine, Ponderosa Pine, and Jeffrey Pine are similar in appearance, and they may grow together. What range of tolerances and requirements can be outlined to explain their differences in distribution?

One important factor is the ratio between photosynthesis and cellular respiration, which is not the same for all plants. Temperatures above or below the optimum tend to decrease photosynthetic rate, and the rate of cellular respiration tends to increase as temperature increases. This increase continues beyond the temperature for optimal photosynthesis, and the result is that cellular respiration requires more carbohydrate than can be produced by photosynthesis. In this way, a lower elevational limit or a limit in southward distribution of any species could be controlled by temperature."(Pp. 110-111).

Yellow Pines attract a variety of insects. Bark beetles, Scolytidae, larva of a butterfly, Pine White, Neophasia menapia, Pandora Moth, Coloradia pandora. The moist Yellow Pine Forest occurs on north facing slopes and at higher elevation that the dry Yellow Pine Forest. In the moist forest, White Fir, Abies concolor, and Sugar Pine, Pinus lambertiana. Douglas Firs, (Pseudotsuga menziesii, are not common but may occur in moist locations on the west slope of the Sierra north of Yosemite Valley. Sugar Pine is the tallest and largest of all pine in the world. "The larges known living specimen is on the western slope of the Sierra in Tuolumne County. It is 216 feet (64.8 m) high and 10 feet (3m) in diameter."(p. 115). "Giant Sierra Redwoods or Giant Sequoias, Sequoiadendron giganteum (fig. 4.34), are the most moisture-demanding of all the species in the Yellow Pine Forest; hence they are absent from the east side of the Sierra as well as most of the west side."(p. 117). "Because the distribution of climatic features required by Sierra Redwoods is so localized, it may be stated that they grow in ecological islands, like the foothill plants mentioned previously that are restricted to certain soils."(p. 117).

Redwoods require fire if they are to perpetuate. The heat opens the cones, which drop the seeds. A long period of no fire enables a deadly fungus to invade the root systems of the conifers, particularly Ponderosa and Jeffrey Pines. "This disease, known as root-rot or Annosus root disease, is killing an inordinate number of trees in Yosemite Valley."(p. 119).

"In the late 1960s and early 1970s the National Park Service began to view fire as a natural component of the ecosystem. Fires at elevations about 8000 feet (2650m) were allowed to burn…The U.S. Forest service has been slow to recognize the value of fire. Suppressing forest fires helps to preserve outside interests like resorts and timber resources."(pp.120-121).

Giant Carpenter Ants, Camponotus laevigatus makes nests hollowing them out, a phenomenon that weakens the structure of the trees. They also eat honeydew, an exudates of aphids that live in White Firs. Other enemies of redwoods are Spruce Budworms, Bark Beetles, Fungi, and Dwarf Mistletoe. A long-horned beetle, Phymatodes nitidus (Cerambycidae) helps cones release their seeds. Chickarees, Tamiasciurus, also known as Douglas Squirrels or Red Squirrels feed on 2 &emdash; 5 year old redwood cones, but as they feed many tiny seeds are released.

Chapter 4 The Sierra Nevada
The Lilies of the Valley

Chapter 4 &endash; pg. 69 to 92


"The primary topographic feature of the state of California is the Sierra Nevada, a tilted fault block approximately 400 miles long and 50 miles wide." The glacier carved scenery is truly a sight to behold (I have had the opportunity to visit the area). The eastern face of the Sierra Nevada is a fault scrap that has been uplifted 11,000 feet above the Owens Valley. The Southern end of the range is bisected by the Kern River which flows southward along a fault. At the southern end there are two high divides: The main divide that goes from Bishop south to Olancha, towering of the Owens Valley. And the Western divide, which extends from Sequoia National Park southward, has peaks that exceed 13,000 feet in elevation. The northern two-thirds of the range, the terrain slopes gradually westward from the main divide to merge with the Central Valley.


Due to the rain-shadow effect, the western slope receives more rain than the eastern slope in the areas around the Great Basin. In the Yosemite area the western slope receives around 75 inches of rain verse the western slope that receives 20 inches. The north receives 55 inches and south of Kern receives 30 inches. What all this means is that as a person ascends up the mountain they will see climate change. The rain fall increase as you go up the mountain until around 8000 to 9000 feet at which time precipitation declines. The lower snow line is around 3000 feet. Above the 3000 foot line the proportion of precipitation that falls as snow increases elevation to as much as 90% of the total. Note that 10 inches of snow is equivalent to 1 inch of rain; thus 80 feet of snow is around 96 inches of rain. Also over half of Sierra precipitation falls during January, February and March.

Temperature is influenced by elevation. The air temperature drops 3 to 5 degrees per 1000 feet due to adiabatic cooling. (Adiabatic cooling is where the air on the surface of the earth will move toward the point of rising air from the north and south. As the air rises, it becomes less dense and thus cooler. Causing water vapor to condenses and fall in the form of rain.) As air becomes drier at higher elevations and also has a lower capacity to hold water due to fewer molecules per unit volume and there are fewer oxygen molecules, thus is the reason that humans have difficulty breathing at the higher elevations. The venturi effect is caused because dry air at high elevation changes temperature rapidly, which creates strong winds that travel at a greater rate as it moves over the peaks and passes. Chimney effect is caused air in the Great Central Valley is heated, and begins to rise. The rising air is caught by the eastward flow over the mountains and is drawn up the canyon to the western slope. The canyons become narrower near the top, causes the wind to move faster as it ascends. The inversion layer is the reason that night time temperatures are colder in the valley and canyons. Another interesting point is that the photochemical production of ozone has caused a loss of chlorophyll in pine trees around Lake Tahoe and Ponderosa Pines in the Yosemite Valley. Also another effect of thin air at higher elevations is an increase in ultraviolet radiation. Short wavelength gives it penetrating power beyond that of other forms of light, which makes it especially harmful to the tissues of plants and animals. Ultraviolet light causes chromosome break and mutations in irradiated tissue.

Also apparent during the ascent up the mountain is the change in soil. The soil becomes course toward the top, so water-holding capacity is greater at the bottom. At the higher elevations almost all soil is decomposed of granite. Podzolization of soil is a result of mountain climate and this type of soil is known as spodosols, which become increasingly acidic at higher elevations. Spodosols are nutrient-deficient. California lilacs have nitrogen-fixing bacteria in their roots, which help deal with nutrient-deficient soil. Fungus improves the absorption of nutrients by the conifers tree, and the tree produces excess carbohydrates for the fungus. That so cool! At high elevations, soil is course and thin. In low places the soil tends to become water-logged because percolation is prevented be bedrock or permafrost, and it freezes solid in cold temperatures. This type of soil is a poor substratum for most plant species and is not a good place for burrowing animals to build a home.

The Sierra Nevada rocks can be divided into three groups:

Batholithic - The batholith resulted as subduction of the ocean floor crust beneath the North American plate caused formation of a pool of magma about 10 miles beneath the surface.

Prebatholithic &endash; Many prebatholithic outcrops are composed of metasediments (metasediments are altered rocks). Metavolcanics are also included in the prebatholithic assemblage. Side note: The longest sequence or metasediments and metavolcanics occur along the western foothills to the northern flank range. These long belts of metamorphic rock are oldest to the east and become progressively younger westward.

Postbatholithic &endash; These rocks of the Sierra are sedimentary and volcanic. Sediments washed westward as the proto-Sierra was eroded, and this sedimentary has continued to the present day. The uplift of the Sierra and the accumulation of sediment in the Great Central Valley during this period is said to have pushed back the sea on the west.

Erosion is believed to remove about 1.5 feet of earth every thousand years. Roof pendants are highly viable because the uppermost portion of the peak is a darkly colored mass of rock, very different from the underlying granitics. The result of metasediments is as follows: Sand stone becomes quartzite, Limestone becomes marble, and shale becomes slate and schist. Mother Nature has demonstrated the perfected example of recycling, now if only humans could follow Mother Nature's example. Where sedimentary rocks are intruded by large masses of granite, deposits of metals such as gold and platinum may be found. At the time of intrusion, hot water driven to the surface by the heat of magma carried gold and quartz in solution. The silica solutions cooled in cracks of the overlying rocks, forming veins, and erosion carried minerals from these deposits out to the valley floor. When the minerals where found at Sutter's Mill the Gold Rush began, searching through gravel is known as placer mining.

"Certain characteristics of granite influence weathering processes. Granite is very hard, and it weathers slowly. But fissures develop in granite along points of structural weakness. These fissures, known as joints, tend to run parallel to north-south axis of the range and also perpendicular to that axis. Granite has a tendency to break up into large cubes." Oddly enough it also seems to expand from the inside, which causes domes to form. The cause of this expansion is not fully understood but one theory is that "the overlaying sedimentary rock was peeled away by erosion, it relieved pressure from the underlying granite. Loss of this overburden allowed the granite to expand from within, causing it to crack in a spherical or onion-peel pattern. Intersections of joints and horizontal cracks have caused the granite to break into large cubes. Freezing of water or growth of roots, forces of mechanical weathering, expand these cracks. Gravity and other erosive forces cause portions of each of these layers to fall away in a process known as exfoliation. These processes &endash; expansion, cracking, weathering, and erosion &endash; have caused the dome shape so characteristic of granitic landforms." Note - mechanical weathering includes &endash; fires, freezing of water, growth of roots, and salt crystal.

Chemical weathering is more subtle. In the desert areas, the dark color on the surface of granitics is a consequence of the oxidation of metals such as iron and manganese. "Water dissolves some minerals and leaves others behind. In granite, the feldspars tend to be more water-soluble; the quartz minerals have low solubility in water. Water dissolves limestone, forming grooves and creases on the surface. If subterranean water saturates a layer of limestone, it can form caverns." Isn't that neat! Other forms of chemical weathering includes: the action of weak acid &endash; which produce small pits in the granite and produces carbonic acid. Carbonic acid attracts crustose lichens (lichens that grow on the surface of rocks) which excrete carbon dioxide which causes further break up of the rock, and causes more cracks and fissures to create more homes for the lichens.

"Mechanical and chemical weathering break up rocks into smaller and smaller particles" and erosion carries them away. The forces of erosion include:

Gravity &endash; occurs on steep slopes - Rock falls, landslides, and avalanches, streams, waterfalls and glaciers are all gravity driven. Talus the piles of rubble at the bottom of the cliff, that resulted from the weathering process and gravity did the rest.

Wind &endash; alpine zone - "Strong winds loaded with sediment produce the sandblast look on the sides of high-elevation trees." The ice particles in the winter have the same affect.

Water &endash; is the primary source of erosive force in the Sierra today. Water carries away rocks before they have a chance to mature. "The Alabama Hills and the rest of the Owens Valley have been dropping while the mountains on both sides have been rising. This is type of valley is called a graben, which means grave in German." Isn't that fascinating?

Glaciers &endash; is the major force for the appearance the Sierras' today. Glaciations "has carved and shaped the terrain and removed most of the soil." A glacier occurs when snow accumulates faster than it melts. Snow becomes thicker which becomes compressed which then flows with gravity down hill. "As the glacier slides down hill, the rocks trapped at its lower surface grinds against the bedrock. This grinding shapes the canyon in a U-shaped trough." "When a glacier retreats, it leaves behind a ridge of rubble known as a moraine. The moraine left at the toe of the glacier is a terminal moraine, and those left along the sides of the glacier are lateral moraines." "Boulders of different compositions from the rock upon which they lie are known as erratics." (Pg. 87) Isn't this an interesting process? There is ever more to this process. "The upper end of a glacier freezes into cracks and fissures, a process that causes more rocks to break off. Sliding of the glacier away from the upper wall of the rock carries off the quarried material, making room for more ice. This process causes the glacier to "eat" its way into the rock at its upper end, and the result is a basin with a circular cliff wall. This type of basin, resembling an amphitheater, is known as a cirque." These cirques lakes occur in a series, one above the other in the canyon, this is known as paternosters (which refers to a string of lakes as if they a sting of beads in a rosary). What happens when the ice melts? "After the ice melts, a deep canyon remains where major ice flow was, but the sides of the canyon, which were not cut as deeply, appear as valleys high up on the wall of the main canyon. These side tributaries are known as hanging valleys." Safety warning &endash; "Walking over polished surfaces should never be attempted next to a cliff, rapids, or a waterfall."

John Muir entered the Sierra Nevada in the 1860's and shocked the geologists by saying that the Sierra's was the result of repeated glaciations. It was later verified that the Yosemite Valley was the ultimate glacial landscape. The floor of the valley is not U-shaped because it is filled with sediment, but other glacial features, such as hanging valleys, cirques, moraines, and erratics, are all evident. Because of it beauty, it was established as a national park in 1866. The information thus far is truly been informative and interesting.

Biotic Zonation, Pages 92 to 126

This section is amazing; I had no idea that Mother Nature was so organized. The distribution of communities in the Sierra Nevada is influenced by elevation, latitude, and rain-shadow effect. The complex interactions of living (biotic &endash; (means living) includes organisms and their interaction) and nonliving (abiotic &endash; (means nonliving) includes, variations of light, heat, water and soil) factors provide an environment known as a habitat.

The biotic zones tend to be displaced downward as a person goes northward. Upper timberline is about 1000 feet lower at the north end of the Sierra than at the southern end. "As one moves to the north, precipitation increases and temperature decrease. Three hundred miles of latitude is roughly equivalent to 1000 feet of elevation." The eastern slopes are drier than the west because of the rain-shadow effect. It is cooler at higher elevations, and cooler temperature means less evaporation, so the water goes farther. The influence of temperature on evaporation is called slope effect. Slope effect is more pronounced at lower elevations and toward the south, resulting in a conspicuous color mosaic.


Valley Grassland is a highly disturbed ecosystem characterized by introduced Mediterranean grasses and weeds that are invading the Foothill Woodland. Grassland communities are associated with deep alluvial soils, with a mixture of trees and grasses often referred to as a savannah.


Foothill Woodland surrounds the Great Central Valley, also known as Oak Woodland. "This is one of California's most widely distributed communities, which covers 10 million acres of California's foothill or low mountain terrain." (Pg. 94) The two most common trees are Digger Pine and Blue Oak. Other plant life includes: Valley Oak, Live Oak, California Buckeyes and Redbuds, Owl Clover and Harlequin Lupine. "The foothill community is drought-adapted." (Pg. 101)


Chaparral communities include several kinds of scrub or shrub. Theses plants species are fire-adapted. Chamise, California Lilac, California Scrub Oak, Live Oak, and Flannel Bush make up a Chaparral communities. John C. Fremont was an explore-army officer who became California's first politician. The journal of the California Native Plant Society is called Fremontia in honor of him.


Edaphic Communities occur where soil is the principal factor to which the community must adapt. A total of 215 species and varieties of plants are restricted (endemic on) serpentine soils in California. Serpentine is the official state rock of California. Serpentine soils are high in magnesium and low in calcium, and contain heavy metals such as cobalt, nickel, and iron. Some of the life within this area includes: Interior Silk Tassel, Leather Oak, Knobcone Pine, Pine Hill Flannel Bush, Lone Buckwheat, Lone Manzanita, a willow, sedge, a lousewort and patches of limestone and marble occur in this region.

"The bulk of animals that live in the desert or scrub communities, are ectothermic and of small size. There are many kinds of insects and reptiles, whose low metabolic rates mean that they require less food, and whose long periods of dormancy enable them to endure the long, hot summer or cold winter" (Pg. 101) which allows them to survive in this area. Interesting fact - Dormancy during the cold period is called hibernation, and dormancy during a warm or dry period is called estivation." Birds and animals cope with harsh habitat through one of two basic strategies. They harvest resources when they are abundant or they change diet with the seasons, feeding on what is abundant. Animals also create niche partitioning. Niche Partitioning is an ecologic term which refers to the "space" in a particular ecosystem occupied by a species. It's the role played by a particular species as it interacts with all other species of an ecosystem. "Ecologic and evolutionary theories predict that an ecological niche can be occupied by only one species at a time." "A consequence of niche partitioning, well illustrated by communities in the Sierra Nevada, is that as one moves up in elevation, an orderly replacement of similar species seems to take place." Another form of niche partitioning is illustrated by groups of similar species that inhibit the same community but utilize in slightly a different ways. For example birds of the same family live in the same area but eat different things. "Woodpeckers are specialized to avoid competition by partitioning food resources in space and time." (Pg. 104) It's a very organized system that allows all species to live together in harmony.

Foothill woodland is the home of a large variety of bird species for which oaks, in particular, are important for food and shelter. The cavities in oak trees are home for a variety of animals, such as Quail, Owls, Gray Squirrels, Nuthatch, Woodpeckers, Western Bluebirds, Western Scrub Jays, Acorn Woodpeckers, Band-tailed Pigeons. Most birds in the foothills are omnivores but acorns are probably the most important food in the foothill. Another fact worth mentioning &endash; "Scrub Jays bury their acorns, and in so doing help plant oak trees." They keep the cycle of life going. Also when a member of the squirrel community, upon noticing danger, emits a shrill squeak, and all potential prey species duck for cover. It is interesting that the alarmist, by attracting attention to itself, is often the only squirrel that is captures and is the oldest squirrel in the colony. By sounding an alarm it protects its offspring. They truly show undying love for their offspring.

Yellow Pine Forest is one of the most widely distributed communities in California, occurring on every mountainous region with sufficient elevation and climates, covering around 14 million acres. It consists of coniferous trees requiring at least 25 inches of precipitation. They include Ponderosa and Jeffery Pines, California Black Oak, Washoe Pine, Sugar Pine, Silver Fir, Red Fir, Douglas fir and Incense Cedar. The distribution of the different trees can be explained by:

1.) The ratio between photosynthesis and cellular respiration. Temperatures above or below the optimum tend to decrease photosynthetic rate, and the rate of cellular respiration tends to increase as temperature increases. This increase continues beyond the temperature for optimal photosynthesis, and the result is that cellular respiration requires more carbohydrate than can be produced by photosynthesis. In this way the lower elevational limit in southwest distribution of any species could be controlled by temperature.

2.) Photosynthesis also requires water; therefore precipitation could limit photosynthetic rate. (Pg. 111)

The question of whether temperature or water, or a combination of the two, limits the respective distributions of these pines has not been answered, but microclimate differences do occur, as illustrated in localities where several species grow in close proximity.

Yellow pines are known to be associated with a wide variety of insects; over 200 species have been catalogued. Such as the Bark beetle, larva of butterfly known as Pine White, Pandora Moth, and Silk moths. Silk moth are interesting because the eat pine needles, and although their cyclical infestations seem to create a lot of damage, they are an important part of the forest ecosystem. They recycle nutrients by converting pine needles to fertilizer that is easily available from the forest floor. They provide short-term abundant food supply for birds and other wildlife and Indians also ate the caterpillars.

Some more fascinating facts:

Chapter 4 Sierra Nevada
by the Star Thistles - Naida Blevins, Miriam Koppel, Tammy Rease and Amber Shrum

Biotic Zonation

The distribution of communities in the Sierra Nevada is influenced by elevation, latitude, rain-shadow effect, and slope effect. Complex interaction of living and nonliving factors provide an environment that is called the habitat. Among the nonliving factors of the environment are variations in light, heat, water and soil. The biotic factors include all the organisms and their interactions. A habitat, therefore, is where organisms live.

The influence of temperature on evaporation is called slope effect. Slope effect is more pronounced at lower elevations, and also toward the south because that is where the growing season is limited by summer drought.


Valley Grassland

Grassland is a community associated with deep alluvial soils. At the perimeter of the Great Central Valley, soils become thinner and water is closer to the surface. Deep-rooted oak trees become scattered among the grasses. This mixture of trees and grasses often is referred to as a Savannah. This is where the Valley Grassland meshes with the Foothill Woodland.


Foothill Woodland

The Foothill Woodland surrounds the Great Central Valley. Also known as Oak Woodland, this is one of California’s most widely distributed communities. Oak Woodland covers about 10 million acres of California’s foothill or low mountain terrain. The two predominant trees found throughout this belt are Digger Pine, and Blue Oak. Although the total number of species and/or subspecies varies with the person doing the classifying, there are at least 20 species of pines and 16 species of oaks in California. The greater portion of these species is truly Californian in distribution, many occur nowhere else.

Pines are more widely distributed in mountain communities, but oaks are more common in communities associated with summer drought.

The first pine encountered in the Sierra Nevada from the Great Central Valley is the Digger Pine. Some authorities object to this name because "Digger" was a derogatory term used for the Miwok Indians, who ate the seeds of these pines. An alternative name that has been proposed is Gray Pine, in reference to its distinctly gray-green foliage. The Digger Pine is characterized by long needles that occur in clumps of three. They are 7 to 13 inches in length. The grayish foliage is sparse enough that the tree is nearly transparent. Cones are quite large, ranging from softball to volleyball size. Scales making up the base of the cone have large hooks on the outer edge. At the base of each of these scales are found large seeds, about the size of kidney beans. These are the seeds that were gathered by the Indians. These seeds, along with acorns from a variety of oaks, are an important food for many foothill animals.

Blue Oak is a member of a subgroup known as white oaks. It is winter-deciduous. Its leaves are about 3 inches long and the margin of the leaf is often composed of seven large lobes, but this is highly variable. Acorns of Blue Oaks are among the most palatable of all the oaks. They are eaten by a variety of bird and mammals and formerly were a staple for the Indians.

Other large oaks found in Foothill Woodland include Valley Oak and Interior Live Oak. Valley Oak is another white oak. It differs from Blue Oak by having larger, greener leaves, with 9 to 11 lobes, and long, narrow acorns. It is often the first oak to invade the grassland. They fell victim to agriculture. Large numbers of these trees have been cut down for firewood and to promote cattle and sheep grazing with the mistaken notion that the amount of grass would be increased if oaks were removed.

Blue Oak is more drought-tolerant that Valley Oak. Blue Oaks forms Savannah’s, but it also occurs in association with Digger Pine on slopes, close together, in a community known as Woodland rather than a Savannah.

Interior Live Oak is an evergreen oak with dark-green leaves that are smooth and hairless on the underside. Leaf margins may be smooth or spine-tipped. Interior Live Oak commonly occurs with Blue Oak and Digger Pine, but it tends to occupy rocky outcrops where its roots tap deeply into cracks and fissures that hold water.

At slightly higher elevations than Blue Oaks, California Buckeyes and Redbuds become common on north-facing slopes. These are small, shrub-like trees. California Buckeye is the only member of the horsechestnut family. California Buckeye is drought-deciduous, dropping its leaves in the summer. They are easily spotted because as their leaves turn brown they appear to be dying. In late summer and fall they are further distinctive because they bear large, pear-like seed pods on naked stems. From these pods come the buckeyes or "horsechestnuts," an important food for some animals.

At scattered localities in the foothills there are Redbuds. They are particularly conspicuous along the Merced River west of Yosemite National Park. During the late winter and early spring these shrub-like trees are covered with small, reddish-pink flowers. They are winter-deciduous, so there are no leaves on them when the flowers appear. Large, heart-shaped leaves remain on the tree through the summer, and large, brown beanpods persist into the next winter. These beanpods are also an important source of food, particularly protein. Nitrogen-fixing bacteria inhabit the roots of these plants.

Oak Woodlands also include a large component of ephemeral or annual plants that grow vigorously and bloom after winter rains. Some of California’s most attractive wildflowers, such as Owl Clover and Harlequin Lupine are found here also. Unfortunately, livestock grazing and the invasion of Mediterranean weeds are eliminating many of these.


Edaphic Communities

Edaphic communities occur where soil is the principle factor to which the community must adapt. A total of 215 species and varieties of plants are restricted to serpentine soils in California. Serpentine endemics are Interior Silk Tassel, Leather Oak, and Knobcone Pine. There are nine species and sub species of butterflies tied to serpentine endemic plants. Limestone endemics are not common in the Sierra, but are Desert Chaparral, Sagebrush Scrub, manzanita, a willow, sedge, and lousewort.



Foothill Animals

Many insects and reptiles endure endemic conditions, due to less need of food and ability to hibernate. The Foothill woodland nocturnal seed-eating rodents are also associated. Conspicuous mammals and birds will be focused on and for two reasons, either they harvest resources or change their diets according to season. Only one animal per niche can survive.



Oaks are the home for a large variety of birds. The Great Horned Owl, California Quail, Gray Squirrels, Woodpeckers, Western Bluebirds and the White breasted Nuthatch. Acorns are the most important food in the foothill. Acorns feed Bandtailed Pigeons, Western Scrub Jays, and Acorn Woodpeckers. In the summer flying insects are a food source for the Black Phoebe, the Western King Bird, Night Hawks, and swallows and swifts. Gleaners are the White-breasted Nuthatch, the Plain Titmouse, vireos, and warblers. Migratory birds are the American Robins in the winter. In autumn the Cedar Waxwings and summer birds were mentioned.



A conspicuous member of the Grassland and Foothill Woodland communities is the California Ground Squirrel. The squirrels diet consists of seeds, herbaceous vegetation, and acorns. Western Gray Squirrels harvest acorns by climbing oaks. Red-tail Hawks prey on California Ground Squirrels. Badgers prey on the ground squirrel and steal their homes. The Burrowing Owl raises its young in abandoned squirrel burrows. To protect themselves baby owls click their beaks together making the sound of a rattlesnake. Squirrels have an alarmist that warns the others and is usually the oldest and the one that is caught by the predator.


Yellow Pine Forest

The Yellow Pine Forest, also known as the Transition Zone, Mixed Coniferous Forest or Lower Montane Forest, this forest contains a mixture of coniferous and winter-deciduous trees. The Western Yellow Pine is the Ponderosa Pine (pinus ponderosa), and is also used to refer to the Jeffery Pine (pinus jeffreyi).

Yellow Pine Forests are the most abundant in California; there are approximately 14 million acres. These forests occur on the east and west slopes of the Sierra Nevada. There are two types of Yellow Pine Forests, dry and moist. Ponderosa Pines, Jeffery Pines, California Black Oak and Incense Cedar occur in dry Yellow Pine Forests. At the foothills Black Oak replaces Blue Oak. Black Oaks can resprout after a fire. Incense Cedars have bright yellow-green scale-like leaves arranged in chains. The bark of the Incense Cedar makes for good tinder.

The Ponderosa and Jeffery Pines are hard to tell apart. Both have needle clusters in threes, the bark on younger trees look similar, though on older trees the Ponderosa bark is brownish yellow, and the Jeffery bark is brownish pink. The primary way to tell the two apart are their cones, though they appear the same if you roll a Ponderosa Pine cone in your hand it will prick you, were as the Jeffery Pine cone will not prick you &emdash; "Prickly Ponderosa" and "Gentle Jeffery". The Digger Pine also looks very similar to the Ponderosa and Jeffery Pines.

The distribution of these trees is based partly by the ratio of photosynthesis and cellular respiration. As temperature increase photosynthesis rises or falls accordingly and cellular respiration typically increases. Ponderosa Pines typically are not found in areas where temperatures get below 30 degrees Fahrenheit. Digger and Jeffery Pines do not occur as often in the stretch from the Pacific Coast to the Rockies.

Anther limiting factor if photosynthesis is water thus the amount of precipitation that falls yearly in a region leads to the determination of which pines grow there. Jeffery Pines have been found to be able to tolerate more cold and less water because of its extensive root system. There is also a theory that Jeffrey Pines are able to survive lighting strikes because of its think bark or the unique chemical nature of the Jeffery Pine.

The idea that temperature and water are factors in the distribution of the different pines is not yet proven, may questions are still left to be answered.

Yellow Pines are associated with a variety of 200 species of insects such as the Pine White butterfly and the Pandora Moth. Indians used to eat the caterpillars by baking them in the hot soil and drying them.

In the Warner Mountains there is another Yellow Pine family member, the Washoe Pine (pinus washoensis). Washoe Pines are found in the higher elevations on the western edge of the Great Basin. The Washoe Pine appears to be a hybrid between the Ponderosa and the Jeffery Pines. Washoes in the Warren Mountains grow among the Quaking Aspen. This area resembles the Rocky Mountain forested areas.

Moist Yellow Pine Forests occur at north-facing slopes and higher elevations than do the dry Yellow Pine Forest. White Fir and Sugar Pine are the primary occupants although there is a dispersal of Ponderosas. Firs are popular as Christmas trees, Silver Firs, Red Firs (which actually have silver tips) and Douglas Firs are typically harvested and sold as Christmas trees.

The Sugar Pine is the tallest and largest of the pine species, the largest specimen is in the Sierra it is 216 feet tall and 10 feet in diameter. The cone of the Sugar Pine is often used as table decoration.

Five-needle pines are common at high elevations. Sugar Pine is moderately shade-tolerant, has thick, fireproof bark, and may survive as long as 500 years. Giant Sierra Redwoods (Giant Sequoias) require the most water out of all the species in the Yellow Pine Forest. With adequate moisture they are the fastest-growing trees in the US. Soil moisture is maintained by runoff, which accumulates in basins of granite or bedrock. Giant Sequoias occur mainly in groves, basins, and on north-facing slopes. It is thought that the distribution of these trees has been altered, as they moved upslope to their present localities as warming and drying occurred following the end of the Pleistocene. The Sierra Redwoods are relics of the Pleistocene. Their existence depends on the climatic features like those of the Sierra (a localized area) and because of this, they are said to grow in ecological islands, which are important in maintaining endemic plant species and make California a special place. Redwoods are fire and insect resistant because of their strong bark and toxic tannins. This protection allows them to last over 2,000 years. Fast growth and long life spans make Redwoods the largest living things in the world. General Sherman in the Sequoia National Park is the largest. It would make enough wood to build 40 five-room houses. It is 273 ft. tall and 36.5 ft. thick at its base.

After the establishment of national parks, giant trees were named in honor of generals and military heroes. Sequoyah was an Indian who established the alphabet for the Cherokee language. Redwood trees were named after him (Sequoias). This changed when it was discovered that Coastal Redwoods and Sierra Redwoods were different, thus giving the name Sequoia to Coastal Redwoods and changing the name to Sequoiadendron for the Sierra Redwoods with a common name of "Giant Sequoia". Sierra Redwood ecology is well known and has long been studied. In the early 1960s it was discovered that Redwoods require fire to perpetuate. The heat opens the cones, releasing the seeds, which germinate after a rain. Fires burn the understory of the Redwood forest loosening and softening the soil. Long periods of fire suppression have had negative effects such as allowing a fungus to invade the root system of conifers (Ponderosa and Jeffery pines) in the Yosemite Valley. This is known as root-rot or Annosus root disease. Morel is a fungus (an edible mushroom) that occurs after a fire, appearing shortly after the snow melts. It is common in near California lilacs in the Yellow Pine Forest. This fungus may cost $250 a pound. Fire-suppression practices by the National Park Service and the U.S. Forest Service took a toll on Redwoods. White Firs encroached upon redwood groves and pose serious risks when fire occurs because their height and flammability. They shade the redwoods and allow fire to reach the top foliage of the trees. In the 70s the National Park Service began to view fire as a natural component of the ecosystem and they began small control burns to reduce fuel buildup. During the summer of 1987 there were many fires in California, mostly caused by lightening strikes. A total of 775,000 acres burned, most of which had been land managed by the Forest Service. Approximately 1.4 billion board feet of timber was damaged with a loss of $140 million. Giant Carpenter Ants also take their toll on redwoods. They hollow out the redwoods to build their nests, thereby weakening the structure of the trees. They feed on honeydew (aphids) that live in white firs (which where encroaching on the redwoods due to prior fire suppression). Spruce Budworms, Bark Beetles, fungi, and Dwarf Mistletoe also do harm to redwoods. Most insect species live amongst redwoods without causing any harm...some are helpful. Phymatodes nitidus (a long-horned beetle) helps cones release their seeds. Amazingly, the cones on redwoods usually remain unopened for about 20 years until fire, insects or sunlight cause them to open. Chickarees (Douglas Squirrels or Red Squirrels) are also beneficial to redwoods. They feed on redwood cones, releasing seeds. Redwood seedlings grow from 6=94 to 2=92 per year. For 600-700 years, the tree retains its spire shape until the uppermost branches reach the top of the canopy, where the branches are able to spread out. The tallest trees are most often struck by lightening, though they usually survive. Their branches fall to the ground and create the fires that burn the understory of the redwood forest. If not protected by bark, the fire may hollow out the tree and if the interior is damaged it may affect the tree's ability to transport water to its crown and the tree may die.

Chapter 4 Summary
The Sierra Nevada (p92-122)
The Chickadees

Biotic Zonation

Biotic communities are distributed in the Sierra Nevada according to elevation, latitude, rain-shadow effect, and slope effect. Where organisms and communities live is called a habitat and is made up of complex interactions of living (biotic) and non-living (abiotic) factors. Habitats are grouped into categories or zones and differ according to location and elevation (as one moves N, precipitation increases and temperature decreases). The different types of zones are: Valley Grassland, Chaparral, Foothill Woodland, Yellow Pine Forest, Lodgepole-Red Fir Forest, Subalpine Forest and Alpine. We will review the first 4 zones listed.


Valley Grasslands


Foothill Woodland



Edaphic Communities

Yellow Pine Forest


Biotic Zonation - Communities in the Sierra Nevada are determined by elevation, latitude, rain-shadow and slope effects. Nonliving (abiotic) factors include the changes in light, heat, water and soil while organisms represent the biotic factors (living things).

The Valley Grassland of the Sierra Nevada consists of Mediterranean grasses and weeds. Sand that has been washed into the valley is abundant. The Foothill Woodlands are covered with drought-tolerant trees such as the Digger Pine and the Blue Oak. Also found in the foothills are the Interior Live Oak and the Valley Oak. Smaller, shrub-like trees, such as the California Buckeyes and the Redbuds are found in the foothills but at slightly higher elevations. Various plants and wildflowers also grow in the area.

Chaparral is found in the area, with most shrubs keeping their leaves year-around, many bearing berries. The western foothills are known for their edaphic communities - communities that must adapt to its soil. Small animals are in abundance in these foothill locations, such as insects, reptiles and rodents.

Mammals and birds are also common inhabitants of the Foothill Woodlands. The oaks are a great source of food and shelter for the many species of birds. The California Quail and the Great Horned Owl use the oaks in this way, along with Woodpeckers, Western Bluebirds and the White-Breasted Nuthatch, among many others. Birds must change their diets with the changing seasons, from acorns to insects. Ground squirrels can be found in both grassland and foothill areas, also eating the acorns. Red-tailed Hawks, Badgers and the Burrowing Owl all prey upon the squirrel for food as well as for the use of its home.

Yellow Pine Forests are known for the presence of Ponderosa or Jeffrey Pines, along with various oaks, and is a widely distributed community, occurring on both east and west slopes of the Sierra Nevada. Bark beetles and various moths are prevalent in the yellow pines. Sugar pines, the tallest and largest pines in the world, are also found in the yellow forest, along with the Giant Sierra Redwoods (or Giant Sequoias) which are high moisture-demanding trees.

Bark of the redwoods is fire resistant and is also toxic to termites and other organisms that try to consume the bark. These factors allow the trees to reach great ages (over 2000 years). Rapid growth rates also allow the trees to reach their large sizes.

There have been great amounts of study done on the ecology of the Sierra Redwoods. However, it was not learned until the 1960's that redwoods do require fire in order to perpetuate. Fire leads to the opening of the cones which allows the seeds to fall to the ground. It has also been found that long periods of fire suppression lead to the development of a deadly fungus within the trees.

Orr Springs Group
Katrena, Debbie, Guadalupe and Juan
Chapter 4 summary pages 92-122

Biotic Zonation

Biotic zonation is influenced by elevation, latitude, rain shadow effect, slope effect, water, heat, light, soil, and interactions of organisms.  Valley Grassland It is a highly disturbed ecosystem characterized by Mediterranean grasses and weeds. It is a community with deep alluvial soils. Plants in this area tend to die every summer and resprout with winter precipitation.  Foothill Woodland It is one of california's most widely distributed communities (10 million acres).

It is composed of a mixture of drought-tolerant species, and the 2 predominant trees are Digger Pine and Blue Oak. Other oaks foun in Foothill Woodland are Valley Oak, and Interior Live Oak.  Chaparral It is an important component of the foothill community. There are several kinds of scrub or shrub. All specials are fire-adapted.

Two varieties of scrub oak occur in California, the California Scrub Oak and a scrub form of Interior Live Oak.  

Edaphic Communities

Occur where soil is the principal factor to which the community must adapt. Serpentine soil is one type found in California. The soil is high in magnesium and low in calcium, and contains heavy metals such as cobalt, nickel, and iron. There are 215 species and varieties of plants that are restricted to this soil, they include Interior Silk Tassel, Leather Oak, and Knobcone Pine. The endemism is not limited to plants, it also includes insects.  

Foothill Animals

The foothill community is drought-adapted, therefore, a greater mass of animals can be supported in a foothill community. The bulk of animals are ectothermic and of small size (insects and reptiles).

The foothill woodland is also home for a large variety of bird species. Birds include Horned Owls, California Quail, Woodpeckers, Western Bluebirds, White-breasted Nuthatch, Band-tailed Pigeons, Scrub Jays, Acorn Woodpeckers, Downy Woodpeckers, Lewis Woodpeckers, Black Phoebe, Swallows, Nighthawks, Western Kingbird, Bats, American Robins, Cedar Waxwings, and Plain Titmouse.  


Mammals found in the foothill woodlands include California Ground Squirrel, Western Gray Squirrels, and badgers.  

Yellow Pine Forest is one of the most widely distributed communities in California. It occurs in both east and west slopes of the Sierra Nevada. It is composed of coniferous trees. It is divided into 2 subgroups dry Yellow Pine Forest and moist Yellow Pine Forest. The dry Yellow Pine Forest has Ponderosa and Jeffrey pines, California Black Oak, and Incense Cedar.
The moist Yellow Pine Forest occurs on north-facing slopes and at higher elevation than the dry Yellow Pine Forest. It is dominated by White Fire and Sugar Pine, and Ponderosa Pine can also be found here.