CALIFORNIA LECTURE
VEGETATION
INTRODUCTION
California vegetation shows a distinct correlation between climate and geographic distribution of native vegetation.
At opposite extremes in Ca are desert shrubs of the arid southwest and the green verdant forests of the humid northwest.
Influences on vegetation include: Climate, Soil, Latitude, Altitude, Slope, Aspect, and ultimately Wildfires
Zonation, or changes across latitudes or altitudes is common in mountainous habitats. Wetter greener vegetation is possible in dry realms of the state where mountains are present.
Soil quality directly affects certain plant types. Chaparral plants are rather fond of thin, underdeveloped soils, especially if the soils are on steep slopes.
Sagebrush, coniferous woodland, and desert shrub also inhabit rather inhospitable places; while Oak woodland and grasslands grow on deeper, more moisture-retentive soils.
Over-urbanization has replaced more farmland than woodland, hence, much of the pre-European vegetation distribution in California is largely unaltered over large tracts of land. However,
logging and re-plantings have over-exploited plant resources in many locales, including Redwoods, Douglas Fir and other coniferous woodlands.
Wildfire is another immediate influence on vegetation. Some vegetation depend on wildfires to periodically clean out the dead and tangled underbrush, allowing for fresh new growth. Certain trees and brush need wildfires for seeds to germinate. In other instances, wildfires can be destructive, eliminating sensitive plants that will not regrow.
MAJOR VEGETATION BIOMES/ASSOCIATIONS
I. Coniferous Forests
Needleleaf evergreen trees
Density, rate of growth, height increases northwestward
In some areas - one or two species dominate an area
Most species are commercially useful
II. Oak Woodland
‘Savannas” - common sight of Oaks trees sprinkled through a field of
grassland
Mostly used for grazing
III. Coniferous Woodland
Sagebrush, scattered pinyon pine or juniper bushes
IV. California prairie
Most of this land has disappeared because of either agricultural or urban uses
Dominated by bunchgrass or other herbaceous plants
V. Chaparral
Broadleaf evergreen shrubs, Oaks, chamise, manzanita, ceanothus
VI. Sagebrush
Similar to chaparral, smaller plants- sagebrush, and grasses
VII. Desert Shrub
Cacti, wildflowers, Joshua trees – Water gatherers, water storers, water opportunists
VIII. Marsh-Grass
Much has been plowed under and drained for agricultural uses.
Remaining is in preserves - waterfowl refuges, etc.
Bulrushes and cattails are common
CONIFEROUS FORESTS
Occupy nearly 1/5 of CA 160,000 square miles
Consists of Redwoods, firs ,pines and other evergreen softwoods
Found along West flanks of Klamath, Cascades, northern Coastal Ranges
and Sierra Nevada (in response to orographic ppt.)
In addition to ample moisture - soil quality, soil moisture, aspect, latitude relative humidity all play a role in favoring growth of thick green forests on west and windward flanks of mountain slopes.
Most trees in this biome represent a climax community - reaching the height of growth and sustainability in this region
Climax communities may take 100s, if not 1000s, of years to attain this status.
World renown: California’s Redwoods unique:
Sequoia (1) Giant Sequoia (Sequoiadendron giganteum)
found in small groves along western slope of Sierra Nevada and
(2) Redwoods (Sequoia sempervirens)
found along western border of North America between Monterrey County north to Oregon border.
Redwoods are among the oldest (General Grant 3,500 years old) and tallest (400 feet) trees in the world.
May be a “living fossil” having survived for the last 100 million years both in California and elsewhere in North America
Endurance possible because:
(1) non-resinous bark(2) no low limbs(3) moist and decay-proof wood (4) abundance of small cones, filled with seeds (5) capable of seed-growth or stump growth (6) some flood tolerance
Survival not dependent only on Winter rains - Redwoods along Coast use ample supply of “fog-drip” to provide up to 20 inches of moisture per summer (supplements the dry summer)
Approximately 2 mya (Pleistocene) Redwoods covered mountains and coast of Northern and Southern California.
Subsequent warming and drying of southern California left only a few remnants of these great forests in the form of
Big-Cone Spruceand Torrey Pine
Increasing demand for this wood has led to q major battle between environmentalists and lumber companies
More than 90% of the old growth stands in California have been harvested.
Some state and national parks established to protect this treasure - but are really so meager in size that private land holdings still allow for unabated removal of these trees.
The bulk of redwood trees still remain in private hands - although a recent agreement with Pacific Lumber and State conservancies have turned over many new acres to the state - for a considerable sum of $$$, of course
Multiple Users also present a problem
(1) tourists(2) mining(3) grazing (4) agriculture
Douglas Fir
Second to Redwoods in popularity is the Douglas Fir, a flexible, knotfree wood
Douglas fir has brought California some fame in that
(1) CA is a close 3rd to Oregon and Washing in lumber producers
(2) forest products represent over 5% of CA economy
(3) A significant # of CA is employed by lumber co - esp. in NW
(4) NW CA economy is mainly derived from lumber industry
Problems: fluctuating demands and uneven economies lead to high unemployment in this field. Many lumbermen blame the “tree-huggers” for thisjob loss....but the reality is the changing demands and fickleness of the
market
An odd fact in this is that even with Douglas Fir being a popular substitute, the eventual loser is still the California Redwood.
Douglas Fir grow faster (30-60 years lifespan) and prosper in drier alpine climates, as well as rainforest climates. This means that when Redwoods are cut down, the area will be re-seeded with Douglas Fir ( quicker profit turnaround) not the very slow=growing Redwoods. Eventually, the faster growing, higher-profit Douglas Firs will eliminate redwoods.
CONIFEROUS FOREST VARIETIES
At various elevations in the Sierra Nevada, a variety of forest woodlands can be encountered
2500-7000 ft: Sierran Yellow Pine Belt, along with Pinus Ponderosa and Sugar Pine (Pinus Lambertiana). Douglas fir, white fir and incense cedar are all found in and around Giant Sequoias.
Yellow pine is second to Douglas first in lumber
7000-9000 ft: Lodge-pole pine-red fir belt with Jeffrey Pine (Pinus Jeffery) and Mountain Hemlock (four more additions to California timber resources)
9500 ft - timberline: forests thins out in scattered groupings of trees on
granite flats
High alpine belt, at elevations of thinning oxygen (and more temperature extremes) includes species of
Sierra Juniper, Limber Pine (Pinus flexilis), Foxtail Pine and Whitebark
Pine
Average precipitation is greatest in the Yellow Pine and Lower Lodgepole-Red Fir Belts, allowing for the growth of deciduous trees such as Aspen, Ferns, Lichens and mosses, as well as other wildflowers (Lupine, for example)
Most PPT at these elevations falls as Snow: (1) insulation for tree (2) reservoir water for tree during dry summer months. Many needle-leaved trees are evergreen, meaning they do not lose leaves - which relieves of the burden of reproducing new growth every spring/summer
California’s generally Mediterranean climate doesn’t allow for the growth of many large deciduous trees in the mountainous regions - rather Evergreen Needleleaf.
WOODLANDS
Oaks, stately trees, scattered throughout rolling terrain of grasses
Found along the foothills of the Cascades and the Sierras, the stream courses of Central Valley, central and southern Coastal Ranges, and inner coastal valleys of southern California (Thousands Oaks, for example
Distribution is based on more water-available locales of higher elevations, and drier grasslands and shrublands of low-lying valleys.
If there is plenty of available moisture (ppt of 10-30 inches/year) a mixture of conifer, broadleaf trees and oaks will be found. Greatest variety between Oak (Quercus) and Pine (Pinus)
California Black Oak, mixes well with Coulter Pine in the Central Coat Ranges south to the Peninsular Ranges (at elevations) - Yearly rainfall ~25 inches. Long warm dry seasons and a variety of soils, with winter frosts
Interior Live Oak is evergreen and associated with chaparral, digger Pine, and Blue Oak. In areas with less ppt (10-20 inches), more drought-resistant than other oaks
Largest of all oaks - Valley Oaks - more than 125 feet tall, associated with Riparian vegetation (and some chaparral, if water is available)
Grasslands - Marshlands of Central Valley
This natural landscape has disappeared under urbanization and agriculture, Once the area of wild Bunchgrass - now invaded by Fescues and other exotics carried in either by settlers, farmers, birds, animals etc.
Domesticated vegetation has all but pushed the natural vegetation out
Bunchgrass grow upright in dense tufts of stems that arise from a perennial root crown. Just before winter rains, grasses produce new growth - are dormant during the winter flowering and blooming to maturity from April to June.
Wildflowers included those in the Lily and Amaryllis families, Sunflowers family, thistles
Marsh vegetation is distributed in distinct bands.\, from rooted plants from shallow water to drier lands. Reedlike plants dominate freshwater marshes falling in four groups> (1) Rushes (2 ) Bulrushes (3) Sedges (4) Cattails
Sedges and rushes are shorter than cattails, without the “pussy willow”, but do have some flowering atop leafless stems.
Other water-loving plants found in marshes include: Willows, Mulefat
Desert Sagebrush
Rainshadow Biome” These plants know how to survive in areas of drought and low moisture. Dryness is usually accompanied with high summer daytime temperatures and below freezing winter nights.
Plants can be thought of as (1) Water gatherers(2) Water storers and
(3) opportunists
Water Gatherers: Keeping ample spaces between each other, these plants send out horizontal roots just below the surface to capture any moisture that may be in the soils just below the surface (Soil water Belt is very narrow in these regions)
Big SagebrushCreosoteBurroweedRabbitbrush
These plants actually do protect the soil from erosion and damage from winds and floods through their network of surface roots.
Larger water-gatherers include: Mesquite and Joshua Trees
Thick barks, waxy leaves, “hairy” leaves all help to prevent moisture loss for these vegetation/plants
Water Storers:
These include Cacti and other Succulents
Store water in their tissues, absorbing water and “puffing” up when full, withering and shrinking when empty
Leathery skin and needles also help with control water losses
Opportunists
These plants remain dormant until sufficient water is available for blooming and regrowth. Wildflowers are especially capable of this type of behavior - Winter rains can signal regrowth and spring blooms. Many rains over long-term necessary - single storm even won’t get it
Chaparral/Coastal Shrublands
Chaparral can be found in most slopes in southern and Central California - include: Laurel Sumac, Purple sage, scrub Oak (chaparro in Spanish)
Thick, evergreen vegetation similar to those found in Med of Europe
Useful in preventing soil erosion, runoff, etc, by holding soils on steep slopes in place.
Produce oils (part of the Xerophyte plant family) that act as incendiary bombs during wildfires. Steep slopes hinder fire-fighting efforts. Fire, however, does help this community - encouraging new growth - clearing out underbrush and dead, etc.
EXOTICS
Brought in by Europeans - some have been too successful - crowding out native trees, and vegetation.
(1) Eucalyptus: brought in for (1) lumber not used (2) Oil - not productive
Now used as windbreaks etc on farms
(2) Tamarisk: another non-native brought into Mojave area to control sand-drift - a plant found in arid eastern Mediterranean - and adapted well to arid deserts in southern California. A pest - the seeds blow everywhere and sprout. They have served their original purposes well.
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© V. Drake
Calveg.