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This 13 page Class Notes was uploaded by Janey Lyon on Monday February 16, 2015. The Class Notes belongs to GEOG 3230 at University of Utah taught by Carter in Spring2015. Since its upload, it has received 108 views. For similar materials see Pyrogeography in Geography at University of Utah.
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Date Created: 02/16/15
Wednesday January 14 2015 THE ORIGIN OF FIRE What is fire Burning combustion and oxidation Three necessary elements Oxygen Fuel and Ignition Oxidation chemically combined with oxygen exothermic reaction gives of heat and light like oxidation endothermic absorbs heat and light Oxygen began accumulating 2 billion years ago Earth is about 4 billion years old for the first 2 billion years there was a lot of sulfuric and carbon dioxide gasses on Earth that kept life from being able to thrive 23 billion years ago blue green algae began to bloom and produce Oxygen about 500000 million year ago those Oxygen levels filled to modern oxygen levels 400 million years ago plant life began to grow which created fuels for fire Fire did not happen until plant fuels began growing GEOLOGIC TIME Protoezaric era Oxygen begins to accumulate Paleozoic era Modern Oxygen levels at 21 Oxygen Devonian era Plant fuels begin to grow Precambrian era makes up 88 of Earth s history IGNITION sparks Volcanism There are about 1520 active volcanoes world wide so they aren t very consistent in igniting flames Meteors rarely hit the Earth these days Falling rocks which are usually human caused Wednesday January 14 2015 lightening is the biggest and most consistent ignition source LIGHTENING forms and accumulation of electrical charges in clouds Hot strikes are slow long and create more energy cold strikes are fast and rarely catch fire as clouds separate positive and negative neutrons separate that create and electromagnetic field that is attracted to the negative energy at the bottom of the clouds Florida has the most days with thunderstorms however the western states experience the most lightening ignition due to extremely dry climates South East soils are saturated so there are no fires Moisture is key to ignition Forest cover types types of fuel Fire Occurrence through time unevenVVhy Carboniferous 354248 mya Oxygen rise to 35 increased global burial of organic matters Charcoal and gas deposits Permian 24865 mya lower fire activity Dehumidified air dry land Mesozoic 24865 mya were periods of low fire Boundary between cretaceous and tertiary KT boundary is a large charcoal deposit 65 mya Present a time of high occurrence of fire Modern oxygen levels at 21 what failed to burn in the old earth is burning in the modern Trend through time is for fire to become more common but less eruptive Principles to guide interpretation of fire s history fire promotes and it purges it upsets shreds reorganizes revives and quickens Wednesday January 14 2015 plants and animals adapt to a pattern of fires fire is as ecologically powerful removed as applied Ecological factor that guides evolution organizes biota and bonds the physical world to the biological Adaptations to fire protective traits protect against fire Promotional traits promote fire The concept of fire regime fuel moisture ENSO El Nino Southern Oscillation Pacific Ocean Atmosphere Teleconnection El Nino and La Nina Sea surface temperatures Southern Oscillation atmospheric pressure Measured by pressure gradients between Tahiti and Darwin Winter Phenomena Normal Pacific conditions include convective circulation El Nino brings low pressure warmth down the coast La Nina brings high pressure cod through the polar jet stream Fuel is the ticket to fire regime ENSO and monsoons drive moisture to fuels and dry out fuels What is a fire island a place not modified by humans No fire degradation due to isolation Wednesday February 11 2015 FIRE FUNDAMENTALS Scales of fire Fundamental scale combustion process fluid dynamics and fuel chemistry Fire Behavior configuration of fire as a whole Landscape scale regional scale relationships with area Global scale atmosphere effects of emissions Combustion Process Overview fire is rapid release of the heat energy stored by photosynthesis think of it as always in motion Equa ons Photosynthesis 002 H20 solar energygt 06H1005n 0 Stores potential energy that is released in combustion Combustion 06H1005n O ignition temp gt 002 H20 heat chemical energy is transformed to thermal energy radiant energy and kinetic energy are in the rising convection column Common fuels are made up of carbon and hydrogen this makes by products of water vapor and CO2 Phases of Fire preignition dries out fuels and is endothermic ignition is the transition of fire combustion is exothermic and it is when the highest billing points are reached Extinction fire goes out Why understand these fundamentals because we can manipulate the processes with retardants fuel arrangement and prescribed fires Intrinsic fuel properties describe plant parts relates to fire fundamentals cellulose hermicellulose and lignin all effect fuel as well as density and heat content 4 Wednesday February 11 2015 Heat and Heat transfer energy moved from one source to another 3 basic mechanisms of transfer conduction molecule to molecule transfer of energy like a fire heating a pot that makes the handle hot convection movement of air masses rising expanding cooling and falling down Like water in the pot that boils up and falls back down radiation energy in waves like the sun Waves of energy decrease with distance influences fuels being cooers to each other slopes of fuels wind and fuel concenUa on Preignition radiant heat drying gt ignition convection rising gt combustion conduction maintains it Fuel consumption During combustion fuels convert to Heat smoke incomplete combustion and charcoal partial combustion Duff layer small fine organic matter Large woody fuels Duff and wood are on the horizon on the humus of the earth Within that top layer there is Oi slightly decomposed litter plants are still recognizable Oe increasing decomposition plant structure recognizable Oa highly decomposed plants unrecognizable Products of consumption smoke emissions and human health particulate matter is at 25 microns and not only gets into our lungs but also can diminish visibility and light fire and GHG s like 002 Wednesday February 11 2015 Phases of Fire Preignition radiant heat is drying convection rising ignition transition combustion conduction at a molecular level extinction fire goes out Wildland Fuel types biomass phytobiomass material above soil plants and duff total fuel potential fuel may burn but not completely available fuel potential dryness to ignite Fuel type the description of the fuels like trees or plants Fuel state moisture or dryness of the fuel Descriptions to consider Properties extrinsic quantity size shape compactness arrangement Components vertical layers ground su ace crown Complexes vegetation type 39 components Wednesday February 11 2015 structure Intrinsic and extrinsic fuel properties plant parts humidity chemical makeup fuel components quantity arrangements 3 basic types of fires 1 ground fires that smolder 2 surface fires that are flaming 3 crown fires that flame into the canopy Changing in Fuel fuels are constantly changing Causes can be disturbance weather and biological time scales of fuel change can be abrupt diurnal seasonal annual or decadal Fuel Moisture state of moisture and need to dry before ignition composition and size solar radiation open v closed canopy varies daily seasonally latitude living fuels are generally in the growing season curing drying plants can have lack of moisture in summer or be dormant in winter Wednesday February 11 2015 FIRE ECOLOGY A branch of ecology that focuses on the origins of wild land fire and relationships with the environment both living and non living Classes describe general fire return interval fire frequency how many years between 2 fire events how many fires occur on a land at any given time gt defined by Henselman in 1981 Class A natural fires rare or absent ex coastal alaska and inland Florida Class B infrequent low intensity surface fires with more than 25 year return interval usually small ex most eastern deciduous forests and some hight subalpine rockies Class C frequent low intensity fires 125 years Class D Severe surface fires 25 year interval sporadic crown fires Class E shorter length interval crown fires High intensity regimes frequent 25100 years Class F high fuel loads every 100300 years Rocky Mountain Classification fire regime rotation high severity vs low severity Wednesday February 11 2015 ecosystem plant adaptations to fire Succession how fast things grow back the series of stages from life to death primary succession exposed bare rock ex Mauna Loa secondary succession fire or damage It is at equilibrium FE Clements suggests succession with out disturbances end up in a climax community He thought disturbances were bad but now we know they are beneficial to ecosystems February 11th 2015 FIRE REGIMES remember there are key components that make up a fire regime like frequency local aspect Fire regime characterizes the spatial and temporal patterns and ecosystem impacts of fire on the landscape The two most important variables determining a fire regime are Vegetation and Climate Fire impacts climate impact vegetation impacts fire etc local to regional scale distinguished by how often they occur frequency fire interval fire rotation distinguish fire regime by fire characteristics surface ground crown fires distinguished by extent size severity and intensity Natural Range of Variability or Historical Range of Variability HRV fundamental to understanding ecosystems 100 years of history help us characterize fire on the landscape But this doesn t get us the full spectrum of the ecosystem and fire Wednesday February 11 2015 refers to ecological conditions the spatial and temporal variations in these conditions within a period of time in an area unaffected by modern people why do we care its important to understand the full range of the spectrum so that we can have a baseline of the natural regime to compare data to We can classify our western US fire regimes 5 main classes in different areas PNW CALI N ROCKIES CO PLATEAU S ROCKIES colorado plateau is having a lot of precip in july and august as a result of the monsoon This is going to create a lot of dry lightening storms PNW Precip during novdecember So fires are more likely during the dry season in the summer Driest during el nino years PinyonJuniper woodlands of the colorado plateau little fire research difficult trees to study Little ecosystem understanding sparse discontinuous fuels However invasive species have made it easier fires common in draught years and high wind pinyon favors high moisture content juniper favors drier conditions 4OO year fire return interval in high severity expansion of invasives like cheatgrass sagebrush and oak grazers like cow and sheep are also altering the regime fire effects and succesion annuals and perennials sprout about two years after fire Junipers have competitive advantage because they are draught tolerant 1O Wednesday February 11 2015 long fire rotation is within the HRV so fire suppression probably hasn t had any affect on the ecosystem kryptobiotic soil can usually withstand fires Quaking Aspen thick bark trees complex fire regime due to moisture availability fire spread is rare thin bark regenerate from suckers adventitious shoots Pando is hypothesized to be one of the oldest living organisms because aspen are all clones of each other They all share one giant root system fire scars are rare here 150 Fire return interval or conifer dominance if they fire does not occur fire effects an suppression high moisture content creates fire break stable aspen communities not dependent on fire successional aspen dependant on fire unless there is conifer encroachment because they will build fuel loads only a few decades worth of data so we don t know a whole lot about how to control it NortWestern FOrests high fuel loads include grand fir doug fir red cedar mosses and lichens maritime influence ENSO influence creates dry summers and explosive fires mixed severity FRI about 500 years for red cedar but HRV not well understood logging impacts the problem Ponderosa Pine 11 Wednesday February 11 2015 highly sensitive to ENSO variability La nina brings dry fires el nino allows snow and understory growth mostly mixed severity very well adapted to fires on the land scape they shed lower branches to keep from crown fires and also have very thick bark to protect 60300 FRI fire severity and size may have increased due to suppression grazing and logging Class C 2 Pyne SageBrush mixed severity 200 FRI spring has high fuel moisture fall has low fuel moisture and fuels dry out and spark can leave a sever mark in the community cheatgrass invasion is a big concern in all communities It has a continuous fuel load CheatGrass excels in warmer and stressed enviros alters fire regimes can germinate in tow season SubAlpine forests lodgepole dominated spruce fir high fuel loads more lightening fire common in lodgepole pine class d mixed to high severity serotinous cones seeds are sealed in wax and doesn t open until hot temps like fire and seeds will go compete stand replacing 150200 year FRI in lodgepole high soil moisture in spruce and fir not adapted to fires thin bark 12 Wednesday February 11 2015 200300 year FRI Mixed conifer 39 150200 FRI tall grass pairie Class 02 Chaparral in SoCal Class E4 well adapted to draught community not just trees Lobloly and shortleaf pine 13
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