Fire has been a part of the history of the Oakland-Berkeley Hills
area throughout its history. As with many other marine climates, fuel
moistures are such that during most periods, fires do not cause dramatic
damage but rather help maintain a balance of fuel types and reduce fuel
loads. The native flora and fauna had adapted correspondingly with the
natural occurrence of fire in the area.
In modem times, the natural fire pattern in the area has been
substantially changed. Fire suppression has reduced the natural cycle of
fires which normally would have occurred in the area. Without prescribed
burning or some other type of fuel reduction, the native vegetation has
caused an increased fuel load through the area.
Additionally, the introduction of vegetative species which are not
native to the area has dramatically impacted fuel loading. This is
particularly true of the introduction of eucalyptus. Fuel accumulations in
some areas under eucalyptus plantations have been estimated between 30
and 40 tons per acre. Monterey Pine was also introduced into the area and
contributed significantly to the fuel loading.
Eucalyptus was first introduced to the East Bay Hills with extensive
planting in the early 1900s. The eucalyptus has a tremendous production
of both leaf and bark litter, which is not readily consumed or broken down
in the normal decomposition process and leads to the presence of high
volumes of fuel.
Additionally, eucalyptus is susceptible to freeze damage, as occurred
in 1972, when large numbers of eucalyptus were killed due to an extended
period of below freezing temperatures, and again in December of 1990.
The dead trees and limbs added a significant amount of dry fuel in the
area. Also, eucalyptus sprouts back from the stump and this sprouting
after freezing or after logging operations has also increased fuels in some
areas.
Fuel loading varied through the fire area and to some degree was
dictated by the topography. The northeast portion of the fire area had
more wildland fuels, while in the south and western areas, the homes were
the major fuels. In effect, the more severe slopes in the north and eastern
portions of the fire area required the use of native species. The more
moderate slopes and deeper soils in the south and southwest areas allowed
for the introduction of more ornamental type species.
Fuel Distribution -- Natural vegetative types through most of the fire
area included some grassland, brushland, mixed broadleaf forest, and
eucalyptus and conifer plantations. Species found in the grassland areas
include various types of needle grass and perennial bunch grasses. Heaving
grazing in the areas in the past resulted in the introduction of various
annual grasses, such as wild and slender oats, barleys, soft chess, other
bromes, and an array of associated annual and perennial herbs.
Additionally, thistles, mustards, and wild oats dominate some of the area.
With the discontinuation of grazing, coyote brush has become established
throughout the grassland area.
The grasslands would contain the lowest fuel loading of the natural
fuels through the area. However, the extended drought may have caused
unusual amounts of dead fuel to accumulate before the fire.
The brushland would probably make up a large portion of the
available fuel, particularly in the northeastern portion of the fire area.
Drier sites would contain such things as silver lupin, California sage, and
bush monkey flower. Other species which might be found would include
poison oak, coffeeberry, ocean spray, and hazelnut. Hard chaparral type
brushland would include alameda and brittleleaf manzanitas, bush
chinquapin, and huckleberry.
Mixed broadleaf forest fuels were located in portions of the fire
area., but were probably not significant in the fuel loading. Species found
would have included coast live oak, California Bay, and California
Buckeye. Some Monterey Pine and eucalyptus may also have been found
scattered through these locations. Understory species would include poison
oak, blackberries, hazelnut, and various herbaceous plants.
Eucalyptus plantations were found at various locations, through the
fire area. Numerous eucalyptus, not specifically in plantations, were also
scattered throughout the fire area.
Conifer species found through most of the area would have been
Ponderosa Pine or the introduced Monterey Pine. There would be also
some minor locations with Coastal Redwood. Monterey Pine plantations
have been established through portions of the area.
In addition to the native species, various ornamental species have
been added throughout the area, particularly in and around the homes.
These fuels appear to be more significant toward the south/southwest of
the fire area.
Fuel Loading - The heaviest fuel loading would probably have
occurred in the untreated eucalyptus stands. Some estimates indicate fuel
loading in these areas from 30 to 50 tons per acre. Additionally, heavy fuel
accumulations would have occurred in the location of the brushlands.
Information indicates that some fuel reduction had been attempted
through portions of the area. Some logging had occurred to thin
eucalyptus stands and some attempts had been made to remove eucalyptus
from certain areas. The East Bay Regional Parks District has used grazing
to reduce fuels in some areas. The amount of fuel reduction conducted by
individual homeowners varied greatly.
Various fuel reduction options need to be considered and developed
in these areas. Prescribed burning and limited grazing by animals such as
goats are two options that have been considered. Mechanical methods of
fuel reduction could also be utilized.
Fire Spread -- Fire spread through the majority of the north and
eastern portion of the fire was probably aided by the continuity of wildland
cover and the rapid burning characteristics species. Most of the residences
and other structures located through this area burned as the result of being
exposed to the fire spreading through the continuous wildland cover. As
the fire progressed into the more heavily populated area to the south and
west, the structures themselves contributed to spreading the fire, assisted by
the wildland and ornamental species.
Entry of fire into the structures through the fire area was closely
associated with the adjacent wildland or ornamental plant species. Many
of the homes in the steeper slope areas had overhanging decks with fuel
accumulations underneath, allowing fire to spread to the decks and into the
structures from below. It appeared from the location of trees around the
homes that fuel accumulations on the roofs probably added to the spread
of fire to the roof coverings and under the eaves. Additionally, fuels in
close proximity to the structures proved to be significant, exposing the
exteriors to extreme radiant heat loads. In may cases the radiant heat
caused interior contents inside windows to ignite.
Strong winds and low fuel moistures resulted in an extremely fast
spread of fire. This was increased by the topography and heavy fuel
loading. The extremely rapid rate of spread, coupled with the difficulty of
control made a frontal attack to stop the forward progress of the fire
almost impossible. Suppression efforts in the initial stages of the fire
consequently had to be defensive action in an attempt to control exposures
and contain the spread on the flanks of the fire.
Spot fires occurred a quarter to a half mile in front of the fire as the
wind carried embers over a large area. Spotting occurred in both wildland
fuels and on top of structures. There were also spot fires occurring in the
various ornamental species and in yards in the more residential areas of
the fire.
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