Lecture 10 Wild fires Flashcards
what is the history of wildfires
increase 10,000 years ago maybe due to warmer drier climate, increased used of fire by humans
what are the requirements for wildfires
fuel, oxygen, heats, if any are lost fire will dissipate
descrbe the pre ignitation phase
pre heating: vegeation reaches a temp at which can ignite
pyrlysis: chemical process of the degration of large hyrocarbons into smaller ones occurs in the presence of heat
preheating and pyrolyss result in feul that is prone to ignite,
describe the combustion phase
starts with ignition (not a single process, not every ignition will result in a while fire) two types of combustion; flaming and smoldering
describe flaming combustion
shifts rapidly, high temp converison of fuel into heat, flames and large amounts of burned material
describe smoldering combustion
occurs in area with burend material as ash covers is a new fuel
what are the transfers of heat
condition, moleucle to molecule contact
radiation; transfer of heat in the for of invisble waces
convection; transer of heat by movement of liquf or gas
describe the heat transfer by wildfires
heat fors raadiation in inainly radiation an onection, as the air is heated it becomes less dense and rises, the rising are removes heat fro the zone of flaming and is replaced by fresh air, this fresh air oxxygen sustains cobustion
what is the extinction phase
point at which combustion ceases, there is no longer heat of feul to sustain a fire
describe feul
anything off the ground, dieases and stroms leads to more ecaying matieral that burns easy
how does fuel conent vary by slope orientation
in NA south facing slopes are relativety warm and dry, slopes ecosed to prevailing winds are often drier, wildfire burin on steep sloes preheat fuel upslope reultin in spreading of fire upslope
what are dry thunderstorms
lighenting prodces whildfries by the rain evaporates before reaching the ground, wind carried embers that ignite spot fires
what are the types of wildfies
calissifed accordin o the layer of fuel
surface; ravel close to the round burning shrubs and leaves
crown fires: move rapidly throgh the forest canopy byflaming combustion
what are the types of crown fires
intermittent crown fires; consume tops of some trees
contionious corwn fire; consumes the tops of all tree
wwhat are the effects of wildfires
fires that burn soil leave behind a hydrophobic layer at the surface which increases runoff an erosion, may persist for several years,
wildfires increae the amount of particle sin the atmosphere which can persist for weeks
what are the linages to climate change
may increase the intensity of wildfires
cause severe drought
forest will expand northward
insect infectation can cause disease making forests more vulnerable
what is the mointain pine bettle
destyes canadian forests, 80% of all mature ress are impacted, consequencewill be felt for decades in BC
what are the impact of wildfire
an lea to evacuation of entire towns, road closures, airport closures, severe property loss, organized evacation has minimized amount of deaths
wha are the impacts of wildfires to animals
most can escape unharmed, rodents can take refuge undergound, can produce open areas sutied for grazing (natural ervice function)
what are the naural service function of wild fires
emprally reduces competition for sunught, some speices triggers relsease of seeds, ash is carbon rich, can remoe microorganisms, removes surface litter
describe yellow stone national park
j
what is fire mamagement
objective is to control wildfires for the benefit of ecosystes while preenting them from harming people and property reuqires research of the fire regine (otential for a wild fire)
wat is fire supression
a stregety to steer the fire into an area with no fuel (natural breaks). reliance of fire supression leds to a buildup of fuel in forest and potential for intense fire
what are perscribed burns
one way to conter the buildup of fuel, purpsofuly ignited to reduce the amount of fuel in forests
