The Los Angeles County Department of Public Works requires that slopes be planted to prevent erosion. At the same time, Public Resources Code 4291 sets standards for Minimum Statewide Clearance of Brush. These are minimal standards and are superseded by Los Angeles County Fire Code Requirements. Indiscriminate clearing of vegetation has resulted in past erosion problems. Fire hazard reduction and erosion control are compatible, however there must exist a compromise. A basic understanding of fire behavior and erosion control will enable Fire Department personnel and the homeowner to work together in meeting these common goals. Vegetation or fuel management is a major component of fire behavior and erosion control. It is the only fire component easily altered by human intervention. No two hillside residents are likely to be faced with exactly the same set of conditions. A number of broad similarities may exist, and it is not possible to make specific recommendations that apply in all cases. Upon request, a forester from the County of Los Angeles Fire Department will make onsite inspections of individual hillside homes. They will advise the homeowner on steps to be taken to minimize the fire hazard and to prevent erosion through vegetative fuel modification, while at the same time creating an aesthetically pleasing landscape.
Fuel management for the homeowner can take several approaches:
Why Native Plants?
There are three major components that comprise the fire environment. The current state of each of the environmental components - fuels, topography, and weather (and their interaction with each other and fire itself) determine the characteristics and behavior of a fire at a given moment. The homeowner can best alter the fuel component of the fire environment. Wildland fire management includes modification of the size, arrangement, and kind of vegetative fuels. This modification reduces the ignition potential, flame length, and the heat output of a fire. Maintenance of both landscaping and structures is essential to fire safety and watershed protection.
Soil erosion is the wearing away of the soil by water, wind, and other forces. It is a process of detachment and transportation of soil particles. Rain failing on bare soil or on soil with sparse vegetative cover detaches soil particles and the runoff carries these particles down the slope. Rills and gullies are cut by the force of the moving water. The severity of erosion is influenced by four physical factors: weather, fuels, soil, and the steepness of slope or topography.
MOISTURE CONTENT is the amount of water in the fuels. The moisture content of plant materials plays a major role in the ignition, development, and spread of fires. Fuel moisture controls the current flammability of fuels both living and dead. Live fuel moisture measurements are taken regularly by County Foresters and utilized by firefighters in predicting fire danger and behavior. During the most active growing periods of spring, the moisture content of plant foliage may be quite high. As the season progresses, a plant’s moisture content declines (late summer or early fall) and the plant becomes dormant or dies completely. These plants can often be rejuvenated and their fire hazard reduced by recharging their lost moisture through supplemental irrigation. Caution must be used to avoid over watering because most drought tolerant species will die if watered too much or too often.
VERTICAL ARRANGEMENT is the relative plant height above ground and the relationship of one plant to another. This influences the fire reaching fuels at various levels. Reducing the height of plants generally results in shorter flame lengths when they burn. Homeowners should keep existing low plants trimmed and eliminate ladder fuels - those that allow the fire to spread to taller plants. All trees and shrubs should be limbed up one-third of their height, up to 20 feet. Multiple trunks or stems can be retained provided smaller branches are removed from the plant. Clean out dead materials under clumps of individual native brush specimens. Commonly found shrubs which are easily transformed into "fire safe" multi-stemmed trees include Sugar Bush, Toyon, Mountain Mahogany, Elderberry and Scrub Oak.
FUEL LOADING is the amount of fuel in a given area expressed in tons/acre. This may vary from a few pounds/acre where shrubs are small and sparse, to fifty tons/acre where shrubs are large and dense. Homeowners can reduce the fuel load by removing all dead material, both on the ground and within the standing vegetation. Thinning the remaining canopy can be done to maintain the same amount of ground coverage and shade. The reduction in fuel loading reduces the heat output, flame lengths, and intensity of the fire.
SIZE AND SHAPE of fuels affects the surface area to volume ratio. Plants with small leaves generally burn quicker and create firebrands which spot and ignite new fires. The homeowner should attempt to keep small-leaved plants trimmed close to the ground. Highly flammable, small-leaved shrubs such as Buckwheat, Chamise, and Sage should be removed completely within 50 feet of any structure unless their removal creates an erosion hazard.
HORIZONTAL CONTINUITY is the distribution of fuels and their relationship to each other. Single specimens of trees, native brush, and ornamental shrubbery may remain provided they are separated and isolated. Horizontal separation should be at least three times the crown diameter of the larger specimens from other native shrubs or 30 feet from the nearest structure. To prevent the transmission of fire from one plant to another, stagger or offset the alignment of remaining specimens.
CHEMICAL PROPERTIES include the presence of volatile substances such as oil, resins, wax, and pitch in the fuels which affect fire. The homeowner should remove target plants which are highly flammable.
SHEET EROSION is the removal of a fairly uniform layer of soil from the land surface as a result of raindrop splash and runoff. Raindrop splash is the impact of the raindrops on the soil surface. The splash detaches soil particles and forms a muddy slick on the soil surface. The flowing water detaches additional soil.
RILL EROSION forms numerous small channels only a few inches deep, occurring mainly on recently cleared soils. These channels may expand to about one foot in width and reflect a great loss of soil.
GULLY EROSION is the process in which a miniature valley is cut by concentrated runoff flowing only during and immediately after heavy rains. The distinction between a gully and rill is depth: If the eroded channel is big enough to block vehicle travel, it is called a gully.
MASS EROSION OR SLUMPING occurs where a hillside becomes so saturated by water that large areas of soil slide or creep downhill. This can also be called SLOPE FAILURE. Unlike other types of erosion, caused by water impacting or running over bare soil, slumping occurs most often on slopes that are well vegetated. Grass covered slopes increase the infiltration of water into the soil. Saturated soil will try to find an area of less stress and flow down hill. The increased weight causes the slope to fail. Slumping will often occur in areas where the base or toe of the slope has been removed by erosion or for road construction. Retaining walls are often used to keep this from happening. The ability of water to break soil particles apart And transport them downhill depends on the speed the water is moving. Doubling the steepness of the slope increases the water velocity by four times and the soil cutting force by 16 times!
A fine textured soil, having large amounts of silt and fine sand, is most susceptible to erosion from rain splash and runoff. Soil structure refers to the arrangement of primary soil particles. It influences both the ability of the soil to absorb water and its physical resistance to erosion. Granular structured soils containing large amounts of fine sands and silts with little clay, are usually more erodible than soils with a blocky or massive structure. The steepness of slope, surface roughness, and the amount and intensity of rainfall governs the velocity of the runoff flowing down the slope. Vegetation is one of the most important factors influencing soil erosion. As in the case of fire hazard reduction, the vegetative cover is the most easily altered by human activity. Vegetation helps control erosion by shielding the soil from the impact of the raindrops, retarding surface flow of water thereby permitting greater infiltration, maintaining a pervious soil surface capable of absorbing water and removing subsurface water between storm events by transpiration, and by slowing the amount and velocity of runoff. The practices of fuel management presented in the fire hazard reduction section are designed to reduce fire risk and severity and at the same time retain enough vegetation on the slopes to control soil loss.
Fuel loading can be significantly reduced without eliminating the valuable canopy. All trees and shrubs that are removed can be chemically stump treated to prevent resprouting. It is highly important to leave all stumps in the ground to stabilize the soil.
Remove needles, leaves, or other vegetative material from the roof of any structure.
SOIL EROSION HAZARD CHECKLIST
When deciding what to plant, the homeowner should select plants for the desirable attributes of fire resistance, low maintenance, availability and erosion control effectiveness. In general, installing smaller plants often produce the best growth. Diversity in plant selection is more desirable than planting only a few types. Spreading shrubs and trees are easier to establish and reduce long-term weed problems often associated with large areas of ground cover. Ground covers like the large leafed Ice Plants (Carpobrotus sp) should be avoided on steep slopes because they are shallow rooted and are heavy due to a high moisture content. This combination can cause them to slide down to the slope if the soil becomes saturated. Deep irrigation practices encourage deep root growth. Drip irrigation will concentrate the water where it is needed. Conventional overhead irrigation often causes erosion on steep slopes. Trees are particularly valuable on steep hillsides. The roots of many trees go much deeper than those of most ground cover plants. Trees that resprout after burning are generally the best choice for wildland areas. You do not have to replant and the roots continue to grow. Selections may include California natives like Coast Live Oak, Valley Oak, Alder and Black Walnut. Numerous plants are available that will suit any situation you may have. The following list offers some of the more common and easier to find selections. Elements of fire hazard reduction and erosion control should help you decide what and where to plant.
County of Los Angeles Fire Department
PUBLIC RESOURCES CODE 4291
Any person that owns, leases, controls, operates, or maintains any building or structure in, upon or adjoining any mountainous area or forest, brush, or grass covered lands or land covered which is covered with flammable material shall at all times do all of the following: (a) maintain around and adjacent to such building or structure a firebreak made by removing and clearing away, for a distance of not less than 30 feet on each side thereof or to the property line, whichever is nearer, all flammable vegetation or combustible growth, (b) maintain around and adjacent to any such building or structure additional fire protection of firebreak made by removing all brush, flammable vegetation or combustible growth which is located 30-100 feet from such building or structure or to the property line whichever is nearer, as may be required by the State Forester when he finds that, because of extra hazardous conditions, a firebreak of only 30 feet is not sufficient to provide reasonable fire safety. Grass and other vegetation located more than 30 feet from such building or structure and less than 18 inches in height above the ground may be maintained where necessary to stabilize the soil and prevent erosion.
Roadways: Remove and clear within 10 feet on each side of every roadway all flammable vegetation or other combustible growth. (F.C. 1117.10)
Clear all hazardous flammable vegetation to mineral soil for a distance of 30 feet from any structure. Cut flammable vegetation to a height of 18 inches for another 70 feet. (F.C. 1117.2.2) Remove that portion of any tree within I0 feet of the outlet of the chimney. (F.C. 1117.2.4) Maintain any tree adjacent to or overhanging any building, free of dead wood. (F.C. 1117.2.5) The Los Angeles County Fire Department requires a clearance of 30 feet or more around all buildings and structures for fire safety.
Remove all flammable vegetation or other combustible growth. This does not apply to single specimen trees, ornamental shrubbery, or cultivated ground covers, provided they do not readily transmit fire. Additional clearance can be required if conditions warrant, up to 200 feet. (F.C. 1117.2.3)
With increasing population pressures, limited water resources and the uncertain weather patterns in Southern California, the need to conserve water is now greater than ever. The area's history of low rainfall virtually guarantees a limited water supply in the future. Since rains and drought are not predictable, we must plan for tomorrow now! A good place to begin is in your yard, garden or other landscaped area.
Nearly half the home water used in Southern California is applied outdoors for watering thirsty lawns, flowers, shrubs, and shade trees. Much of this water is wasted, because most plants will survive on considerably less water than they are receiving. In many cases, they will look their best and live longer with less. Many plant problems are directly or indirectly linked to over watering. Amending watering habits along with the use of xerophytic (drought tolerant) plants is an excellent way to reduce water consumption—and save money at the same time. All that is required to create a water-saving landscape is some xerophytic knowledge and careful planning.
A Xerophyte is a plant structurally adapted to growing under very dry or desert conditions. These plants often have greatly reduced leaf surfaces for avoiding water loss; they have thick, fleshy parts for water storage; and hairs, spines, or thorns to discourage browsing by animals.
DON'T OVER WATER:
Following guidelines established in several available publications to determine how much water your irrigation applies in 15 minutes. The test utilizes measurements from scattered containers (such as cans or coffee cups). In addition, it also shows you which areas of your lawn are getting more water than others. This will allow you to adjust the system to water more uniformly. No matter how carefully you water, you will still have to deal with runoff if you irrigate with a conventional overhead system. There are simple ways of catching excess water. Shallow trenches or basins around plants will hold water until it seeps into the ground. DETERMINE the amount of water in the soil before you water. You may not need to water! Irrigate only when the soil is dry. ADJUST to the seasons and weather by changing the length of time you water during different times of the year.
INSTALL AUTOMATIC CONTROLLERS, THESE CAN BE:
AUTOMATIC SHUT OFF OVERIDE:
Additional water savings can be accomplished if existing spray type heads are replaced with bubblers or drip systems where appropriate in tree, shrub, or groundcover areas. In this way, water is applied directly where the plant needs it. By installing or converting your current system to a drip irrigation system, you can conserve water and increase the drought tolerance of your landscape plants. Drip irrigation also promotes deep watering. A deep-water reserve will help extend watering cycles for longer periods. USE MULCH on top of the soil 3-4 inches thick to conserve moisture and control weeds.
General Watering Requirements for Newly Established Plants:
ONGOING: During very dry years, deep watering in early spring or summer may be required by drought tolerant species if winter rains have not adequately recharged the soil moisture. If soil moisture is adequate at the start, watering may not be required at all.
WATER DEFICIENCY SYMPTOMS
When the water supply to plants is insufficient, leaves wilt and young shoots droop; if
the situation persists, the tips and margins of leaves begin to brown and the condition
spreads to the veins. The oldest leaves on weak branches begin to fall.
BACCIIARIS PILULARIS (Dwarf Coyote Bush): High growing ground cover or low growing foliage mass. This California native grows to a height of 24 inches and spreads to 6 feet. A very dependable bank cover. Readily available.
CEDRUS DEODARA (Deodar Cedar): Large evergreen tree with gray-green foliage and a bent-over top. Grows to a height of 80 feet and has a 40 foot diameter branch sweep. Roots probably go as deep as its branches grow wide. It does not suffer from lack of summer water. Should not be used in areas where Brush Fires occur. Readily available.
CASSIA ARTEMISIOIDES (Feathery Cassia): An Australian native with attractive foliage and large showy yellow flowers. Can grow to 5 feet in height. Will hold up through the worst California summers without supplemental water. Not commonly available, but worth looking for.
CEANOTHUS SPP. (Ceanothus): This group of shrub is made up of primarily California natives ranging in size from a few inches (prostrate form) to 14 feet high. These plants feature dark green leaves and attractive dark blue or lavender flowers. Most are unthirsty, but many can tolerate some irrigation. Generally available.
DODONAEA VISCOSA (Hopseed Bush): Medium-sized shrub native to Arizona with willow-like green or bronze-purple leaves. Will grow to over12 feet tall. It is an exemplary no-irrigation shrub, but needs some water in desert situations. Can be damaged by frost in inland and desert areas. Readily available.
FESTUCA OVINA GLAUCA (Blue Fescue): A small, clumping, perennial grass comprised of bluish green leaves with wheat colored flower plumes which occur from spring to summer. As grasses go, this one requires little water.
LANTANA SPP. (Lantana): Group of shrubs best known for their ability to cover the landscape and provide a profuse display of colorful flowers. Will grow 6 feet high and is very wide spreading. This tropical native is as drought tolerant as most plants can be. Damaged by frost, but is very commonly available in milder climates. LAGERSTROEMIA INDICA 'TUSCARORA' (Crape Myrtle): Deciduous shrub or tree requiring infrequent, deep watering. Attractive trunk and branches when grown as a tree. Many color varieties; long flowering period from July through September.
HETEROMELES ARBUTIFOLIA (Toyon): Southern California native shrub or small tree, 10 to 35 feet tall. Good screen and bank plant with abundant colorful red berries in winter. Normally lives on just the rain, but needs supplemental water in desert climates.One of the best natives for landscape use. Generally available.
NERIUM OLEANDER (Oleander): An extremely tough plant, oleanders are useful as hedges, screens, or for planting on banks. Most flower throughout the summer. This Mediterranean native grows to 12 feet high and as wide. Does fine with or without supplemental watering. Readily available.
OLEA EUROPAEA (Olive): Mediterranean native tree growing to a height of 30 feet and as wide. A choice tree with picturesque branch structure and willowy foliage. The fruit can become a nuisance. Holds up well under most drought situations. Readily available.
QUERCUS SPP. (Oak): Slow growing, large sturdy trees to 90 feet high or more and native to the northern hemisphere. Evergreen or deciduous, they can become the dominant tree in many landscape situations. Deep roots allow oaks to get water from many feet down. Readily available.
ROSEMARINUS OFFICINALIS prostratus (Dwarf Rosemary): To 2 feet tall with spreading habit. Rosemary tolerates a wide range of growing conditions; enduring both hot sun and temperatures to around 15 degrees Fahrenheit. Widely available.
SALVIA GREGGII (Autumn Sage): Bushy shrub growing 3 feet in height, spreading to 3 feet. Flowers in many colors, late spring through winter. Requires little to no irrigation near the coast, benefits from some water and shade inland.
SANTOLINA CHAECYPARISSUS (Lavender Cotton): Small evergreen sub-shrub or ground cover with attractive yellow flowers. This Mediterranean area native will grow to 2 feet in height. Generally does better under drought conditions than when watered. Commonly available.
XYLOSMA CONGESTUM (Xylosma): A very graceful, spreading, evergreen shrub with shiny, light green foliage growing to 10 feet tall. It is native to southeast China. Will survive any dryness, but might look sparse during the worst dry spells. Readily available.
YUCCA SPP. (Yucca): A large group of evergreen stemless shrubs with clusters of sword-shaped leaves native to North America. Good plants for desert gardens, but some varieties may reach 20 feet tall. Can be dry all summer and give no indication of trouble Generally available.
What would you expect if your landscape could not be watered this year and next? With a water conserving landscape it would stay healthy, and can be more beautiful than a high water using one. Plants that depend upon frequent watering would wilt, possibly die, and in doing so become highly flammable, thus creating a fire hazard for you and your neighbors. Even if drought were not a problem in Southern California, local sources of water are scarce. We must import most of the water we depend upon from distant sources. This is expensive; and as our population increases, it creates an ever increasing demand for our limited water. There are a number of water saving planting ideas you can utilize. REPLACE thirsty (high water usage) plants with ones that require less water.
DEEP, INFREQUENT WATERING ENCOURAGES ROOTS TO GROW DEEP. THE PLANT WILL REQUIRE MUCH LESS WATER ONCE IT IS ESTABLISHED, AND WILL WITHSTAND DROUGHT
CONDITIONS. SHALLOW, FREQUENT WATERING KEEPS ROOTS CLOSE TO THE TOP SURFACE OF THE SOIL. THE PLANT BECOMES DEPENDENT UPON CONSTANT IRRIGATION. TOO MUCH TOP GROWTH IS CREATED COMPARED TO ROOT MASS, AND THIS CAN’T BE SUPPORTED IF IRRIGATION IS SUDDENLY UNAVAILABLE.
These plants have ways of reducing water loss. Their leaves may be small, gray-colored, leathery, or arranged to reduce the amount of sunlight that strikes them. Their stomata [pores] may be structured to conserve moisture. Group Plants According to Their Water Needs: If a few water thirsty annuals and other plants are desired, keep these separate and if possible on a separate irrigation schedule from others that need less water. Keep plants that need a little water apart from those that need none at all
PLANTS TO MATCH SITE CONDITIONS:
Plants on the northern, shady side of a building or wall will need less moisture than those on a hot, sunny, south-facing slope. Many landscaped areas have restricted supplies of water. Paving and buildings can reduce the amount of moisture that reaches root zones and can also increase transpiration through reflected solar radiation.
AREAS TO THE NORTH & EAST WILL GET MORE SHADE. IT WILL BE COOLER, AND PLANTS WILL NEED LESS WATER. WEST & SOUTH OF THE BUILDING WILL BE HOTTER AND DRIER
Use Alternatives to Large Areas of Turf: Lawns use water. Not only do they require more water, they are almost always over watered. Unless lawns are actively used for sports or other activities, consider alternatives that are less costly and time consuming for you as well as being water conserving.
These alternatives also allow for percolation of water into the soil, unlike paved areas. If lawn is used, consider replacing it with a less water consuming variety. In addition, do not cut a lawn too short: irrigation water evaporates more quickly. A grass's root depth may be an important factor in your choice of grass type: shallow-rooted grasses need to be watered more often for shorter periods of time than deep-rooted grasses, which require deep watering less frequently. CONSIDER EROSION CONTROL and FIRE SAFETY in hillside and brush covered areas. Use low fuel volume plants or fire resistive vegetation. Keep area clear of unwanted weeds and litter. Properly space large shrubs and trees. Remove unwanted dead wood from shrubs and trees. Maintain cleared areas around structures. Plant large trees and shrubs away from structures.
LIST OF LOCAL RESOURCES
Sample of available publications:
A Mediterranean climate is one that features mild wet winters and mostly rainless summers.
In urban California, Eucalyptus has become one of the more common broadleaf trees.Imported from Australia as early as 1860, these trees are well adapted to California's climate. Many varieties have become important landscape plants, and have been used extensively in windbreak and woodlot plantings. Until recently these trees have thrived without the threat of major pests. In 1984 the discovery of the Eucalyptus Longhorn Borer, Phoracantha semipunctata, in Orange County revealed the presence of this natural pest from Australia in the United States. The Eucalyptus Borer has now spread throughout California. This borer has now been joined by a number of additional pests that threaten the existence of Eucalyptus in California. Many thousands of Eucalyptus have been lost in recent years. In order to stop, or at least slow, this onslaught of alien insect invaders we must work together in preserving these trees. The following is only a partial list of these pests and the damage that they cause: Redgum Lerp Psyllid (Glycaspis brimblecombei) – First discovered in 1998 in El Monte, California, it is now widespread. These small insects attack seemingly healthy trees and can cause complete defoliation to occur. Eventually the tree may succumb to repeated defoliation and die, or may be attacked by another pest.
Lemongum Lerp Psyllid (Eucalyptolyma maideni) – First discovered in California in 2000 in Los Angeles. This insect is similar to the psyllid above. Both pests infest a variety of Eucalyptus species. Longhorned Borers (Phoracantha semipunctata and P. recurva) – Both species of Longhorn Borer readily infest trees that are stressed by over pruning, drought, and those weakened by other Eucalyptus pests. The larvae of these beetles bore into the tree eating the cambium layer as the go. Eventually the tree will die. They will also infest the wood of Eucalyptus that has been cut down. Eucalyptus Snout Beetle (Gonipterus scutellatus) - First discovered in 1994 in Somis, California. Chews on leaves and young foliage and can completely defoliate a tree. Australian Tortoise Beetle (Trachymela sloanei) – First discovered in California in 1998. Chews on leaves and young foliage and, like the Eucalyptus Snout Beetle, can completely defoliate a tree.
TRANSPORTATION OF EUCALYPTUS FIREWOOD: Assembly Bill 3820 --The transportation of infested wood to other areas is an important factor in the spread of the Longhorn Borers. Assembly Bill 3820 has added the Counties of Los Angeles, Santa Barbara, Ventura, Orange, San Bernardino, San Diego, Riverside and Imperial to a law regulating the transport of Eucalyptus firewood and other minor forest products. As of January 1, 1989, Section 4714.5 of the Public Resources Code reads:
"The movement of Eucalyptus wood containing live Eucalyptus Longhorn Beetles or their larvae in trucks or trailers is prohibited. A violation of this section is a misdemeanor punishable by a fine of not more than one thousand dollars ($1,000), or by imprisonment in a county jail for not more than six months, or by both that fine and imprisonment."
Control of the Eucalyptus pests could be several years away, but some preventative measures can be taken:
LOS ANGELES COUNTY AGRICULTURAL COMMISSIONER
Brush Clearance Unit
Environmental Review Unit
Fire Plan/Interpretive Unit
Fuel Modification Unit
Henninger Flats Forestry Unit
Lake Hughes Forestry Unit
Malibu Forestry Unit
San Dimas Forestry Unit
Saugus Forestry Unit
Vegetation Management Unit
The watersheds and wildlands of the Pacific Southwest have a highly flammable vegetative cover of the plant community described as chaparral and often referred to as brushlands. The introduction of structures and developments into these areas and their encroachment upon the chaparral urban interface area presents a challenge to surviving in these sensitive fire and flood prone areas. The key to minimizing property losses in this environment is to aggressively and effectively manage for its protection. Although several publications have been available to assist the property owner, few give the comprehensive overview this site attempts in a practical manner through the application of time proven basic principles and guidelines. It promotes the concept of "self-help" and "property-owner responsibility". Public as well as appropriate private agencies are available and should be consulted, if necessary, for advice and assistance. It is advisable to verify local codes and ordinances with the appropriate authority because requirements sometimes vary in different jurisdictions. This site provides brief descriptions of the chaparral plant community; watershed and fire management considerations; improving safety in the home's environment; landscaping and its maintenance for fire and watershed safety; protection of life and property a wildfire; and post fire emergency measures.
Planning and prevention will optimize the chances for the survival of your property. Herbaceous native plants and aerially seeded ryegrass cover the mountains again at the end of the rainy season after a fall fire.
California's chaparral plant communities consist of many different woody shrubs and herbaceous species that have adapted over millions of years to frequent fires and extended periods of drought. The mixture of plant species in the chaparral communities varies with such factors as aspect and steepness of slope, soils, elevation, fire frequency, and local climate. Although California's climate causes chaparral vegetation to be especially subject to large devastating wildfires, similar plant communities and associated fire and watershed problems occur in other western states and countries with a similar mediterranean-type climate. Chaparral communities are characterized by a rich diversity of plant species.
Although no single characteristic is present in all chaparral species, several adaptations to the hot, dry climate commonly occur. For example, some species have thick leathery leaves that are small or even needle-like. This design helps the plants to tolerate severe summer drought. Other drought tolerance characteristics include waxy and hairy leaf surfaces and leaves that have a high aromatic oil content. Some plants become dormant and shed some or all of their leaves during prolonged drought. A deep, extensive root system which increases drought tolerance and plant survival on steep slopes is another characteristic common to many chaparral species.
Chaparral plants survive periodic fire by sprouting and by germination of seeds stimulated by the fire. Soon after burning, new sprouts grow from the root, dormant bulbs and root crowns of many plants. Then, fall and winter rains trigger prolific germination of herbaceous species, often resulting in a colorful array of wildflowers in spring. Seeds of woody plants also germinate prolifically.
Plant species differ in their susceptibility to fire. Their age and physiological state (whether flowering or dormant, for example) also influence how well they burn. For chaparral-type vegetation in general, the most important factors influencing flammability and fire behavior are fuel moisture (the moisture content of living and dead plant material), fuel loading (the amount of plant material per unit area), and the ratio of fine dead fuel to living fuel. Fuel moisture is high in winter and spring, but gradually decreases during the hot, dry summer months. The dead-to-live ratio, as well as the fuel loading, increase, causing increased fire danger as plants mature and become old.
Fire history records indicate that plant succession patterns influence fire frequency in chaparral communities. Chances of having a second fire within the first few years after an area burns are high because of the flashy herbaceous fuels such as grasses and flowering annual plants that follow the first burn. These plants readily become dry and carry a low-intensity fire. As the woody plants begin to dominate an area again, germination of the shorter-lived herbaceous species is inhibited. This greatly reduces fire danger for approximately the next 10 years because of the high proportion of live, succulent plant parts and the low proportion of fine dead material on the shrubs.
Fire frequency tends to be greatest in a subunit of chaparral called coastal sage scrub. This specialized chaparral type is dominated by plants that tend to grow more herbaceous material each year than do woody chaparral shrubs. Plants and soil on south-facing slopes are drier than on north-facing slopes because they are exposed to more direct heat from the sun. Species on these sites burn more readily than vegetation on cooler, wetter sites.
WATRESHED MANAGEMENT CONSIDERATIONS
A watershed can be defined as all the land and water within the confines of a drainage area. Its depth extends from the top of the vegetation through the soil to the underlying geologic strata that restrict water movement. Chaparral soils and their underlying soil mantle can store great quantities of water. Rainfall intensities rarely exceed the soil infiltration rate of well-vegetated chaparral watersheds. Watershed problems occur when protective vegetation is removed as by wildfire or land development.
The main objective in watershed management of chaparral lands is to maintain vigorous multi-aged stands of vegetation which can respond favorably to periodic disturbance by fire. The main objective in homeowner watershed management is to reduce fire hazards while maintaining deep-rooted, healthy vegetation that will stabilize the watershed and control the flow of water from it. Soils engineering and structural techniques may also be necessary to control runoff and proper drainage. In order to meet the various objectives, a watershed has to be managed as a unit and the soil erosional processes must be well understood. The first requirement means cooperation among property owners, the second is outlined below.EROSIONAL PROCESSES
Chaparral vegetation is commonly found on steep hillsides, even on slopes that exceed the angle of repose (this is the steepest angle that bare soil will maintain). For most natural slopes and most soils, this angle is about 34° (67%). Beyond this angle, soil and rocks are totally under the influence of gravity and may slide downhill unless anchored by plants. Vegetative cover, root depth, and root strength affect the extent to which landslides occur. Slope failures are much less common with deep-rooted vegetation than with shallow rooted grasses, and with dry soils than with soils saturated by winter rains or over watering.
A large landslide on slopes covered with chaparral. A large landslide on slopes covered
with coastal sage. A landslide in a residential area. Slope failures after annual grasses have
replaced the deep-rooted native vegetation. Landslides often result when the toe (base) of a slope is undercut so that hillside stability is weakened.
Soil slips and landslides account for almost 50% of the total erosion on a watershed. Unlike dry creep, these soil movements normally occur when the soil is saturated. They are readily visible and directly translate into financial losses to downstream as well as upstream homeowners. When heavy rains fall on hillsides left bare by fire or improper brush clearance, the water cannot percolate rapidly enough into the soil, running instead over the soil surface and causing excessive erosion and swollen
Normally, slight water repellency of soils is caused by the breakdown of organic material and certain chemicals in plant litter. Hot fires accentuate this by concentrating these water repellent chemicals. Some of the chemicals are volatilized by heat from the fire, resulting in gases that penetrate deeper into the soil. There the gases cool and condense, coating the soil particles with the water repellent substances. Since rains cannot readily penetrate this layer of coated soil particles, water quickly saturates the shallow wet table surface layer. Sheet or rill erosion occurs after the surface layer is saturated.
FIRE MANAGEMENT CONSIDERATIONS
Wildland fire management attempts to predict and control fire behavior by managing and modifying vegetative fuels to control flame length, rate of spread, potential for spot fires, and heat intensity.
Topography is also a critical factor in fire safety. It affects wind speed and direction, and is responsible for differences in heat radiation and fire spread. The most important topographic effect to remember is that fire spreads much faster uphill than downhill without significant wind influence. Ignition A fire is the flame, heat, and light caused by burning (oxidation) after an object has reached ignition temperatures and has been ignited. Ignition temperatures are influenced by the rate of airflow, rate of heating, and size and shape of the object. Once ignition has occurred, sustained combustion requires a continuous supply of oxygen, fuel, and heat.
Wildland fuels, such as grasses, coastal sage scrub, chaparral, and trees, have various ignition requirements which depend largely on their moisture content and size. For example, dry grass has the lowest heat requirement for ignition, and grassy areas therefore have the highest fire frequency. Woody chaparral shrubs in coastal areas normally do not become dangerously dry until late summer or fall.
Reducing the duration of heat and length of flames produced by nearby vegetation can be critical to protecting your home from fire. Flame length in chaparral fuels can be reduced by maintaining low-growing, widely-spaced plants. For example, on steep slopes, 30-foot flames occur in 6-foot-tall mature chaparral at winds of less than 10 miles per hour. Reducing the vegetation to 2 feet in height would reduce the flames to 10 feet. When wind speed increases to 50 mph, as it often does during extreme Santa Ana weather conditions, the flame length for 2-foot-tall continuous fuels increases to 35 feet and for 6-foot-tall fuels to more than 100 feet.
The duration of heat can also be a critical factor. For example, the time period for heavy chaparral fuels to be consumed may be more than 10 minutes, but if the continuity and height of such fuels can be reduced, the duration of the flame and its associated heat can often be shortened to seconds. Thus, a yard tree which may take several minutes to burn may represent a greater hazard to a home than nearby discontinuous chaparral.
Even in light fuels, convection currents in steep terrain can create long flames that can ignite a house. This burning mountain shows that houses situated on ridges and side slope are extremely vulnerable to fire. Fine dead fuels in the interior crown make many broad-leaved trees flammable. Conifers generally are also highly flammable and produce long flames. Winds tend to channel through natural chimneys, making narrow canyons and saddles particularly fire-prone.
The fire safety of a home depends on the continuity and loading of the fuels around it, the location of the home with respect to topography and the design and materials of the structure itself. Legal Brush Clearance Requirements Fire Code 11.702b, 11.703 requires clearance of flammable vegetation for a
The relationship between topography and fire behavior is a factor over which the homeowner has little control. He should, however, be aware of the relationship as it relates specifically to his property. Figure 3 points out that homes located in natural chimneys, such as narrow canyons and saddles, are especially fire-prone because winds are funneled into these canyons and eddies are created. Studies on homes burned along ridges have shown that homes located where a canyon meets a ridge are more likely to burn than other ridge-top homes. In very steep and narrow canyons, radiating heat may
Building density and design are important safety considerations because a burning home can ignite adjacent homes. The roof is the most vulnerable part of a home because it is exposed to airborne sparks. The wood shingle roof has been the single most important element in home losses during wildland fires. It is also a major source of airborne firebrands capable of igniting nearby structures. Studies of structural losses during wildfire in Southern California have shown that with 100 feet of brush clearance, a home with a wooden roof has a 21-times greater chance of burning than a home with a non-wood roof. Although most fire insurance rates are approximately 25% higher for wood roofs than for non wood roofs, this rate does not compensate for the true difference in risk. Exterior materials used on wildland homes should have a fire-resistance rating of 1 to 2 hours, meaning that they should consist of materials such as stucco, metal-siding, brick, concrete block, and rock. This is especially critical for parts of a home exposed to winds from the north or east, or that are
Fire safety is further increased by fuel reduction to twice (200 ft.) the legal minimum (100 ft.). Slope stability is maintained by retaining native plant specimens. The flame length is still continuous but the amount and duration of the heat output is greatly reduced compared to a 100-foot or less clearance.
1. Fire-resistant roof; preferably Class-A such as tile
YOUR POOL AS AN AUXILLIARY WATER SOURCE
Pools can provide a convenient water source for use before or during a fire. Fire engines should be able to get within 10 feet (horizontally) of the pool. If this is not possible, the pool should be equipped with a bottom drain and pipe system that terminates horizontally or below pool level in a 2½-inch valved standpipe equipped with a fire hydrant with national standard thread. A floating pool pump or portable gasoline pump with adequate hose, nozzle, and a suction hose that can reach the bottom of the pool will assure a usable water source even when water pressure and electricity fail.
Fabric fire hoses are suitable for use with pool pumps that are designed for firefighting, but should not be used on home faucets because they readily kink as water pressure drops. All outdoor faucets should be equipped with strong 5/8-inch rubber hoses that will not burst when the nozzle is turned off. A ladder should be available to reach the roof.
1. Wood Shingle roof
The following safety features may save your home during a wildfire:
LANDSCAPING FOR FIRE AND WATERSHED SAFETY
One key to landscaping in fire-prone watershed areas is to selectively replace highly flammable native plants with low-growing, less flammable plants of equal root depth and root strength. In reality, optimum rooting depth and fuel volume generally work at odds with one another. That is, low-growing plants usually have relatively shallow root systems and tall plants have relatively deep and broad lateral root systems. Landscaping requires a compromise between minimizing fuel volume and maximizing root depth.
ROOTING DEPTH AND FUEL VOLUME
Inter planting is also required in stabilization of fill slopes. Plants called "Woody ground covers" generally are deeper rooted, with roots ranging from 3 to 6 feet in depth, and can be effectively used on slopes in conjunction with taller shrubs and trees. Most plant species found in the coastal sage community fall into this root depth category. Plants with roots ranging from 6 to 15 feet or more in depth include most woody shrubs in the chaparral community as well as small, drought - tolerant landscape trees. Very few commercially available woody ground covers, with the exception perhaps of prostrate (Twin Peaks) coyote brush and prostrate acacia, have an effective root depth greater than 6 feet. Plants with roots much in excess of 15 feet include some native shrubs such as scrub oak and laurel sumac, and trees of larger stature.
Drought tolerance and sprouting ability are also important considerations when selecting plants. The plant's ability to survive on little water and resprout after a fire can mean savings over the years on water bills, Deep-rooted coyote brush is a good drought tolerant ground cover for moderately steep slopes. maintenance costs, replanting costs, and hillside repairs. Semi-woody ground covers like vinca and ivy, woody ground covers like coyote brush, hedges such as oleander and myoporum, and even some coniferous trees like Canary Island pine and Chir pine do not need to be replanted because they resprout readily. Most native Chaparral plants also resprout, and some native shrubs such as sugarbush, scrub oak, ceanothus, sumac and chokecherries can be nurtured into short stemmed trees. At spacing's of about 25 feet, these plants can be kept relatively fire safe through occasional pruning. Re sprouting broad-leaved trees, such as oaks, California pepper, sycamore, black locust, and California laurel, to name just a few, can be effectively blended into the landscape setting. For fire safety, trees must be pruned and should be limited to the number necessary to provide shade and slope stability.
The use of herbicides must be closely monitored in hillside landscaping. Over application can kill landscape plants and sterilize soils. The deepest rooted chaparral shrubs are the hardest to kill with herbicides. Since these shrubs serve the dual function of anchoring the soil to the bedrock and extracting water out of the ground, soil slippage is minimal where they are present. Mortality of such plants often results in soil slippage 5 to 10 years later, after the roots have rotted away. The original cause of such delayed slippage is seldom recognized.
Test plantings such as these indicate that Acacia ongerup (arrow) is a highly drought tolerant and fast growing woody ground cover. slopes recommended. However, there is no guarantee that the species prevent slippage when the soil becomes saturated. Inter planting ground covers with shrubs and trees, as discussed earlier, will maximize slope stability. Plants that require high maintenance or that are readily browsed, such as most ceanothus species, are not included in Table 1. The columns in Table 1 headed "aspect," "soil depth," and "irrigation" must be read as a unit. Soil depth figures apply to medium textured, loamy soils. The irrigation figures apply to coastal regions of Southern California and attempt to show relative watering needs of the plants listed. The figures assume that soil moisture is recharged to 12- inch depth during watering. In reality, this goal is rarely achieved through overhead watering because of sprinkler design and time period necessary for irrigation. The
The term "fire retardant" as used in Table 1 reflects differences in fuel volume,inherent flammability characteristics of the plant, and ease of fire spread. For example, under extreme autumn fire conditions, on steep slopes with non gusting winds of 30 mph, a 2-foot-tall solid ground cover with "high" fire retardance is expected to produce flame lengths of less than 10 feet and to reduce the rate of fire spread. Under similar conditions, a plant with "low" fire retardance may ignite readily, will carry the fire, and can produce flames approaching 25 feet in length. For comparison, mature chaparral
The following example will illustrate the use of Table 1. Capeweed is listed in row 1 of the table. Column 1 shows that the species is most effective for planting on slopes not exceeding 25° but may be used on a limited scale on slightly steeper slopes. The shallow root system of capeweed may trigger soil slippage. The next three columns are to be read as a unit and show the relationship between aspect, soil depth, and irrigation requirements. For example, the first line shows that on a north-to-east aspect with less than 1 foot of soil depth, established plants require summer irrigation once to twice a month. The remaining columns are self-explanatory.
A wise homeowner will acquire the written opinion of a geologist regarding slope stability before planting ice plant extensively on slopes in excess of 15°. Most species of ice plant are best suited for rock garden situations or for harsher sites with relatively stable geology and thin soils.
Slope engineering techniques such as concrete contour bench and down drains, designed to slow and direct excess water flow, are necessary on most steep slopes around homes. Their use becomes critical when modification of native vegetation is attempted in geologically unstable areas or areas with past soil-slip problems. The homeowner is responsible for the maintenance of any drainage devices on his land and the devices should be listed in the property deed for permanent record. Any modification of vegetation on the hillside where the sedimentary layering (dip) of the bedrock parallels the slope, as shown in Figure 7 should be undertaken with extreme caution because of the natural instability of the slope. Increasing the infiltration rate of water into the soil and reducing the root strength and root depth per unit area can result in almost immediate soil liquefaction during winter rains.
More information on various aspects of hillside landscaping including slope engineering techniques, proper watering methods, plant selection, and selective brush conversion is available. No book, however, should be a substitute for onsite expert advice from specialists familiar with hillside landscaping and hillside problems. Landscape plants such as Italian cypress, junipers, and most pines are highly flammable. Even mature ivy will burn. Rock strata may determine hillside problems. Citrus orchards make good greenbelts and reduce firespread. Bench drains enhance slope stability, they break up the length of the slope and allow a greater choice of species for landscaping.
MAINTANANCE FOR FIRE AND WATERSHED SAFETY
Landscape maintenance is necessary to keep man-made structures separated from surrounding vegetative fuels; to keep the amount of vegetative fuels at a safe level; to create a safety zone for residents, firefighters, and fire equipment; and to assure that water flow from the property is channeled properly. Giving priorities to maintenance needs and carrying out maintenance and safety inspections on a regular basis is the key to minimizing the effects of natural disasters.
For fire and watershed maintenance, the area around the home should be divided
1. 0 to 30 feet: year-round maintenance
MAINTENANCE ADJACENT TO THE HOME
The area within 30 feet of the home is most critical for fire and watershed safety. Maintenance of nonflammable landscaping such as lawns, border plantings, flower gardens and vegetable beds, and structures such as pools, concrete decks, and recreation areas helps to reduce fire hazard close to the home. This area, is generally level and all water from it should drain toward the street. Rain gutters, pipes, and drainage devices should be cleaned on a regular basis. Additionally, all leaves should be removed from the roof before the fire season begins.
Foundation shrubs and trees are a necessary part of the landscaping. However,
To maintain healthy plants and strong root systems, pruning of most native plants should be done during the summer. Ground cover shrubs may also need to be thinned periodically. In thinning and pruning, care must be taken not to expose the soil surface more than can be safely covered by surrounding plants before the rainy season. Well-pruned, healthy shrubs require several years to build up an excess of flammable live and dead fuel. Therefore, a complete maintenance job can last a long time. Watershed problems in this greenbelt zone are often critical. Before the winter rainy season, all drainage devices must be inspected to insure that they are functional and not clogged with debris.
After major storms, all rain gutters, pipes, concrete bench and down drains, and other such devices must be re inspected. Bench drains are easily blocked by minor soil slips. This forces uncontrolled water flow over the slope and results in supersaturated soils and mud flow. Rodents such as gophers and ground squirrels can be a major cause for soil slips because they weaken root systems and build underground tunnels where water can concentrate.
GREENBELT EXTENSION PAST 100 FEET
The intensity of fire maintenance beyond 100 feet from the home is dictated by topography and design of the structure. Minimum maintenance for a home designed with fire safety in mind should consist of reducing the amount and continuity of the vegetation as well as thinning out the most flammable species. Selective maintenance can be done in areas where topography is favorable and geology stable (gentle slopes, rock outcroppings, etc.) every 10 years or less without causing any accelerated soil erosion. Such "feathering out" of older vegetation on portions of a watershed while
WHAT TO DO WHEN CAUGHT IN A WILDFIRE
If your home is threatened by wildfire, you may be contacted by a fire or law enforcement official and advised to evacuate. If you are not contacted in time to evacuate, or if you decide to stay with your home, the following suggestions will increase your chances of safely and successfully defending your property. Before the fire approaches—notify the Fire Department:
1. If you plan to stay, evacuate your pets and all family members who are not essential to protecting the home, but do not jeopardize your life.
AFTER THE FIRE PASSES:
Your careful planning and action during a fire can save your home. Be prepared. Talk with your neighbors to see what resources you have. Ask your fire personnel for professional advice and assistance.
WHEN CAUGHT IN THE OPEN :
Road Cut: If caught without shelter along a road, lie face down along the road cut or the ditch on the uphill side (less fuel and less convection heat). Cover yourself with anything that will shield you from the heat of the fire.
Canyons: Never be caught by fire in dead-end canyons; they form natural chimneys. These are narrow, steep canyons that concentrate heat, explosive gases, and updraft. Temperatures may exceed several thousand degrees Fahrenheit during a fire.
Saddles: While hiking out of an area where fire is in progress, avoid topographic saddles if possible. Saddles are wide natural paths for wind and fire.
Other Areas: Look for areas with sparse fuel (for example, soft chaparral such as black sage or grassland rather than chamise chaparral), if possible, within a depression. Clear as much fuel as you can while the fire is approaching and then lie face down in the depression and cover yourself with anything that will shield you from the heat. Smoke may create as great a survival problem as the flames do. If you are caught on a steep mountaintop or sharp ridge, the back-side (or fire leeward side) will provide more safety. Be aware, however, that fire eddies often curl over ridges. Before hiking in fire-prone areas, seek additional advice from wildland firefighting agencies. They may supply pamphlets and can give you specific tips for wildland fire survival.
EVACUATION AND ROAD CLOSURES
The Fire Department is responsible for determining when the need for evacuation exists and the jurisdictional law enforcement agency is responsible for carrying out an ordered evacuation. The purpose is to protect people from life threatening situations. Section 409.5 of the California Penal Code provides the legal authority for law enforcement officers to close and restrict access to disaster areas.
The news media is legally exempt from this provision. A person has the right to stay on his property if he so desires, if in doing so that person IS NOT hindering the efforts of fire personnel or contributing to the danger of the disaster situation. In fires or floods, able-bodied persons who wish to remain may be able to aid fire personnel in saving their property, and those who are desirous of remaining may be permitted to do so. It is highly possible that in a fire or flood there will be several different phases of road closure within the disaster area. (1) In an area that forseeably could be involved in the disaster, but presently is not, entry will be restricted to reduce traffic problems or the potential for looting. (2) In an area of imminent danger with limited access or egress, people would be discouraged from entry, though they live in the area. Those who are adamant after being informed of the danger, would be permitted entry. (3) In an area presently involved in the emergency where extreme danger to life exists and where traffic must be restricted due to movement of emergency vehicles, people, including residents, will be refused entry. Road closures around emergency incidents are essential to the expeditious movement of persons leaving the area and mobility of emergency equipment. On major incidents, closures become immediately essential to permit accessibility of fire fighting forces, orderly evacuation, and exclusion of unauthorized persons.
REMEMBER—WILDFIRE IS ERRATIC, UNPREDICTABLE AND USUALLY UNDERESTIMATED. LIFE SAFETY IS ALWAYS THE MOST IMPORTANT CONSIDERATION.
POST FIRE EMERGENCY MEASURES
The steps to take in emergency rehabilitation of an area after a fire depends on the location, the time of year, the intensity of the fire, the erosion potential and the kinds of plants present. If the fire occurs in midsummer and the burned watershed cover consists primarily of landscape plants with a large proportion of resprouting ground covers and shrubs, all that may be necessary for rehabilitation is to periodically irrigate and fertilize. Adequate moisture, heat, and nutrients will encourage rapid resprouting so that a good foundation plant cover can be established before the heavy winter rains return.
Post-fire management of native plants is similar to the procedure outlined above. Plants should be allowed to resprout and establish themselves from seed. Thinning of seedlings, as well as removal of dead stems and branches, can begin the following spring after the rainy season is over. The first year's thinning of native plants should be very light, followed by heavier thinning's the second and third year after clear species patterns and densities have emerged.
Timing becomes critical when a hot fire occurs in late fall. In neighborhoods where steep, long slopes overlook canyons and endanger the lives and property of canyon residents, neighbors should work together to quickly establish an emergency vegetation cover before heavy winter rains begin. Vegetative Measures Emergency seeding by public agencies primarily employ ryegrass to compliment nature's post-fire herbaceous plants. However, ryegrass seeds exposed at the soil surface will not germinate and root unless encouraged by 4 to 5 days of moist, overcast weather.
Seeds of annual grasses present before the fire are incorporated into the soil layer and will quickly germinate with any moisture. The least time and labor consuming emergency measure for homeowners is to broadcast annual ryegrass at the rate of 15 to 30 lb./acre, rake the seeds 1/2 inch into the soil where feasible and then water lightly and regularly. Watering may be necessary two
Grasses have fibrous root systems that are very effective in competing for soil moisture. When replanting shrubs or ground covers is planned for the spring or begins immediately after the fire, annual grasses must be separated from such plants and should be seeded in contour rows. Such rows should parallel the slope and are easily established with a hoe. They should be spaced about 3 feet apart but could be closer in steeper terrain and on fine textured soils with low infiltration rates. The ground covers are planted between the contour rows.
Contours are very effective in reducing erosion because the ridges and trenches form a series of mini-terraces allowing water to infiltrate into the soil. This increases plant growth, reduces runoff, conserves soil moisture, and prevents soil losses. Do not use contour rows in active landslide areas. Cover these with plastic using the guidelines discussed in the next section. Barley is an effective species for contour row planting. Seeds should be presoaked overnight. The water, which may contain germination-inhibiting substances leached from the seed coat, should be channeled into the street.
The recommended seeding rate is 150 lb./acre with an equal amount of ammonium phosphate fertilizer. Seeds should be buried 1/2- to 1-inch deep and the soil tamped. Where possible, the site should be watered to promote rapid germination. Barley is readily available from feed stores,but obtain only re cleaned barley; rolled barley (used for feed) will not germinate. Annual plants such as ryegrass and barley die with the return of hot weather and then present a fire hazard which, in turn, must be mitigated. Mechanical Measures Flood control agencies in many jurisdictions provide excellent advice and pamphlets on mechanical measures for use in emergency situations. The most effective methods for homeowner use are wooden deflector barriers (usually plywood) and sandbags that re channel mudflow safely. Sandbags divert flowing mud. Sandbags should be filled half-full with sand or soil and the flaps tied under and pointed in the direction of the water source. Bags should be tamped and tightly fitted and each layer staggered, as when building a brick wall. Rows should not be more than three layers high unless they are pyramidal or supported by a building.
Some other effective measures are check dams to reduce gully erosion, chain link fences to control rock fall, guniting of steep slopes and spreading of plastic to eliminate water infiltration. Plastic sheets should be a minimum of 6 millimeters (0.006-inchthick).
The slope should be covered completely and the plastic should be anchored by partially filled sandbags. On steep slopes, the sandbags should be connected using ropes. Plastic sheets that cover only a small section of a slope (as when some sheets have blown away) concentrate the rainwater and can be responsible for localized saturated soils, slippage and erosion.
BRUSH CLEARANCE INFORMATION
You are only required to clear your own property. Clearance on other property is the responsibility of the owner. Contact your local forestry or fire personnel if such clearance is needed.
A successful vegetation management program requires an action plan based upon timely planning, thinning and/or removal of plant material. Too often vegetation is allowed to grow unmanaged until it becomes a critical fire hazard. Generally when this occurs, extensive effort is required by the property owner to mitigate the problem.
All vegetation, in any condition, is stored solar energy waiting to be liberated. This is sometimes known as vegetation fuel loading. The energy equivalent equals approximately 8500 BTUs per pound. Because vegetation ages as it grows, it eventually becomes decadent. The dead to live ratio of vegetation increases and eventually, within 10 to 20 years, becomes burnable because of the fine dead material it contains. Sometimes it becomes explosive in the way it propagates fire. Under Santa Ana weather conditions, when the temperature and wind speed are high and the relative humidity is low, fire spreads very quickly. Extreme fire hazard conditions exists in old growth brush stands when fuel loading reaches 40 tons per acre and the stand is comprised of 60% dead material.
Methods presently available for vegetation management include hand labor where individual plants are cut and hauled away or chipped on site. This method is highly labor intensive, but may be the best near structures where other methods are not practical. Other methods include the use of tractors and discs, grazing or browse animals, chemicals for growth control and prescribed burning.
The primary vegetation management objective for fire safety is to deny the fire fuel by which it can spread. Prescribed burning, or the art and science of applying fire under controlled conditions to achieve a predetermined goal, is sometimes used to reduce the vegetation fuel loading and break up the continuity of the fuel bed by which a fire can propagate. Areas thus burned will essentially starve a wildfire of the fuel it needs to spread rapidly. Some pre burned areas may burn again after a few years, but when they do, they will not offer fire suppression forces the high resistance to control as untreated areas. Attempts at fuel reduction, using prescribed fire, should be under the supervision of a professional wildlands manager.
Large vegetative fuel load reduction projects may be accomplished under the State of California Department of Forestry's Vegetation Management Program or other local fire departments that may have their own fuel management programs. Please contact the Forestry Division of the County of Los Angeles Fire Department at (323) 890-4330 for further information regarding vegetation management programs.
TYPICAL FIRE HAZARD REDUCTION REQUIREMENTS:
1. CLEAR all hazardous flammable vegetation away from structure for a distance of 30 feet. Cut flammable vegetation to a height of 18 inches for another 70 feet. Extra hazardous conditions may require an additional 100 feet of fuels reduction. Exception: This does not apply to single specimens of trees, ornamental shrubbery or cultivated ground cover such as green grass, ivy, succulents, or similar plants used as ground cover, provided that they do not form a means of readily transmitting fire from native growth to any structure.
For further information please call or write: