Fire In Ecology PDF

Fire in Ecology - - - - - - - Disturbance Succession: primary (colonization of pilot fire) and secondary (process of change after disturbance) o Pattern of change in ecosystem Fire Ecology is a very recent field o “Ecology”: 1866 (Haeckel) o “Ecosystem”: 1935 (Tansley) o Tall Timbers Fire Ecology co...

Fire in Ecology - - - - - - - Disturbance Succession: primary (colonization of pilot fire) and secondary (process of change after disturbance) o Pattern of change in ecosystem Fire Ecology is a very recent field o “Ecology”: 1866 (Haeckel) o “Ecosystem”: 1935 (Tansley) o Tall Timbers Fire Ecology course 1962 = first time fire and ecology were combined (E.V. Komarek) Combustion: high temperature exothermic redox chemical reaction o Chemical chain reaction o Rapid oxidation o Exothermic reaction (releases heat) o Similar to rusting and decomposition o Necessary components: fuel, oxygen, and heat (fire triangle) Fuel o Burnable material o Any state of matter (solid liquid, gas) ▪ Solids and liquids generally break down first ▪ Only gas creates flames Oxygen o Sourced from the atmosphere (~21%) o To burn, 16% oxygen is needed Heat o Dries material o Begins breakdown o Ignition source (i.e. lightning) Energy (heat) release from combustion mainly comes from O 2 o O=O is relatively weak o H-O-H or O-C-O bonds are stronger (less potential energy, therefore less energy is released) Phases of Combustion - - Pre-ignition/pre-heat o Endothermic (absorbs heat?) o Warming of material o Dehydration o Volatilization o Pyrolysis: thermal degradation of the fuel ▪ Results in gasses, tar (semi-volatile), and char (solid) ▪ Begins in pre-ignition, but continues through combustion Ignition: transition to combustion o Exothermic - - Combustion o Exothermic o Flaming: traditional fire o Smoldering: not enough smoke vapors remain, but smoke is still present o Glowing: no smoke Extinction: not enough heat to maintain combustion Methods of Heat Transfer - Radiation (i.e. if you can feel heat from a fire you aren’t next to) (heat goes up) - Conduction - Convection Combustion is Complex and Variable - Wood Combustion Stages and Products (graph) Stage 1: Dehydration; Stage 2: Pyrolysis & Gasification; Stage 3: Flaming; Stage 4: Char Combustion; Ash Fire Spread and Grow - - Ignition; transition to spreading fire; spreads in all directions; moves fastest in the direction of the wind Parts of the fire: o Origin o Perimeter o Head o Back/Rear/Base/Heel o Flanks (left or right, looking from the heel) o Finger o Pocket o Island (unburned section) o Spot fire