Fire Regimes and Fire Regimes and Pyrodiversity Pyrodiversity ESPM 134 ESPM 134 Spring 2008 Spring 2008 Rick Everett Rick Everett
Where we’re going today: Where we’re going today: � Start integrating previous lecture information Start integrating previous lecture information � with the effects of fire as a disturbance factor in with the effects of fire as a disturbance factor in forested ecosystems forested ecosystems – – � Revisit Fire Regimes � Revisit Fire Regimes Revisit Fire Regimes Revisit Fire Regimes � Pyrodiversity Pyrodiversity � Fire as a formative agent in biological systems Fire as a formative agent in biological systems Set up for Prescription fires & management, Set up for Prescription fires & management, Restoration Restoration
Fire Regimes Fire Regimes � 5 Components: 5 Components: � � Fire Frequency Fire Frequency � Seasonality Seasonality � Fire Severity Fire Severity � Dimensionality (SIZE) Dimensionality (SIZE) � Interactive Syntax Interactive Syntax � What other disturbance factors contribute to the regime? What other disturbance factors contribute to the regime? � Insects Insects � Disease Disease � Climate Climate
Fire Regimes Fire Regimes � Agee, James K. 1996. Fire Regimes and Agee, James K. 1996. Fire Regimes and � Approaches for Determining Fire History Approaches for Determining Fire History � (Attached to your handout, and on the web .ppt) (Attached to your handout, and on the web .ppt) � Fire Regimes Fire Regimes � Defining using severity: Defining using severity: � Low Low � Moderate Moderate � High High
Agee, continued Agee, continued � Fire Histories Fire Histories � Point Frequencies Point Frequencies � Low to moderate fire frequencies Low to moderate fire frequencies � Area Frequencies Area Frequencies � Moderate to very high fire frequencies…stand replacement events Moderate to very high fire frequencies…stand replacement events � Natural Fire Rotation � N t N t Natural Fire Rotation l Fi l Fi R t ti R t ti � Fire rotation is the time required for an area equal to the entire area of Fire rotation is the time required for an area equal to the entire area of interest to burn and is expressed in terms of years per area (125 years for interest to burn and is expressed in terms of years per area (125 years for a 40,000 ha area). a 40,000 ha area). � Fire Cycle Fire Cycle � Average stand age of a forest whose age distribution fits a mathematical Average stand age of a forest whose age distribution fits a mathematical distribution distribution � Usually a Weibull, non Usually a Weibull, non- -parametric distribution parametric distribution
Fire Frequency Fire Frequency � # of fires per unit time in a specific area # of fires per unit time in a specific area � � Example: 10 fires in 100 ha every 100 years Example: 10 fires in 100 ha every 100 years
Seasonality Seasonality � Description of the time of the year that fires occur: Description of the time of the year that fires occur: Spring, Summer, Fall Spring, Summer, Fall � Only can be an estimation of Season, not a calendar Only can be an estimation of Season, not a calendar date… date… � Immense effect on plant ecosystem Immense effect on plant ecosystem � Fire during “unexpected” period (plant hasn’t developed a life Fire during “unexpected” period (plant hasn’t developed a life history which handles fire during a given season) history which handles fire during a given season) hi hi hi h h hi h h dl dl fi fi d d i i i i ) ) � Even holding fire intensity constant, mortality can be greatly Even holding fire intensity constant, mortality can be greatly increased increased � Affecting: Affecting: � Phenology (leafing & buds) Phenology (leafing & buds) � Water availability & uptake Water availability & uptake � Organism activity (especially arthropods) Organism activity (especially arthropods)
Fire Severity Fire Severity � Degree of alteration of vegetation & soils by fire Degree of alteration of vegetation & soils by fire � � Relative…varies by system Relative…varies by system � � Usually thought of as: Usually thought of as: � � Amount of crown scorch Amount of crown scorch � Height of bark char Height of bark char � Amount of plant consumption (live & dead fuels) Amount of plant consumption (live & dead fuels) � Plant mortalities Plant mortalities
Low severity: unburned duff, cone, match!
Fire Severity Fire Severity � Individual tree Individual tree � damage: damage: � Foliage & Bud Foliage & Bud Damage Damage � Cambial kill Cambial kill – – bole & bole & leaders leaders leaders leaders � Root Damage Root Damage – – poorly poorly studied (mycorhizal, studied (mycorhizal, too) too) � 60º C kills tissues (we 60º C kills tissues (we blister…plant vascular blister…plant vascular tissues die tissues die
� Larger Scale damage: Larger Scale damage: � Soils Soils � Heating & sterilization Heating & sterilization � Volatilization & Hydrophobicity Volatilization & Hydrophobicity � Bulk Density Bulk Density � Chemistry (Nitrogen export) Chemistry (Nitrogen export) � Water Water � Changes local water potenital Changes local water potenital g g p p � Loss of photosynthetic crown : Loss of photosynthetic crown : commensurate rise in commensurate rise in watertable watertable � Changes in percolation, Changes in percolation, holding capacitance holding capacitance � Mudflows & Runoff Mudflows & Runoff
Dimensions Dimensions � Size of fire (hectares or acres) Size of fire (hectares or acres) � � Another ‘Dimension’: Another ‘Dimension’: � � Unburned area within fires Unburned area within fires � Degree of ‘patchiness’ Degree of ‘patchiness’ � Low and moderate severity fires in coniferous non Low and moderate severity fires in coniferous non- - stand replacement systems probably left a varied stand replacement systems probably left a varied d d l l b bl l f b bl l f i d i d ‘patchy’ mosaic of burned & unburned areas, leading ‘patchy’ mosaic of burned & unburned areas, leading to: to: � Uneven aged stand structure Uneven aged stand structure � Unburned Patches: Unburned Patches: � Wildlife Refuge Wildlife Refuge � Seed source Seed source
Interactions with other disturbance Interactions with other disturbance agents agents � Insects, pathogens, drought, etc. Insects, pathogens, drought, etc. � Before Fire Before Fire � Insects, pathogens & other agents may increase mortality, Insects, pathogens & other agents may increase mortality, leading to increased aerial & ladder fuels…increasing leading to increased aerial & ladder fuels…increasing intensity intensity � After Fire After Fire � Insects often key into dead or wounded trees Insects often key into dead or wounded trees � Fire Fire- -related stresses in plants may increase pathogen related stresses in plants may increase pathogen susceptibility susceptibility � In general: hard to predict, but large In general: hard to predict, but large- -scale & important scale & important
Lake Arrowhead, SBNF July 2003
Prehistoric Fire Intervals Prehistoric Fire Intervals � ‘prehistoric’ generally refers to fire regimes seen prior to ‘prehistoric’ generally refers to fire regimes seen prior to 1850 in California 1850 in California � Reconstructed using fire Reconstructed using fire- -scar dendrochronology scar dendrochronology � Both season, and date, can be developed from Fire Both season, and date, can be developed from Fire- -scar scar dendrochronology dendrochronology � Reconstructed using geomorphologically Reconstructed using geomorphologically- -derived derived � Carbon Carbon- -dates dates � Phytoliths Phytoliths � Generally driven by ignition sources…. Generally driven by ignition sources….
Lightning Lightning � Current theory: Current theory: � High negative charge builds up in High negative charge builds up in clouds clouds � Electrons stripped off of water & snow Electrons stripped off of water & snow droplets as they are repeatedly lifted & droplets as they are repeatedly lifted & descend within the cloud. descend within the cloud. � ‘Stepped leaders’ form every 50 meters ‘Stepped leaders’ form every 50 meters � Ultimately seek high positive charge near Ultimately seek high positive charge near g ground ground � Up to 2 km from flux source Up to 2 km from flux source � Nasty: Nasty: � 40 Kiloamperes 40 Kiloamperes � Bolt Temperature: 30000º C, nearby air Bolt Temperature: 30000º C, nearby air temperature 10000º C temperature 10000º C � 1 gigavolt, 100 terwatts 1 gigavolt, 100 terwatts � So: no problem with providing a source So: no problem with providing a source of ignition & ‘push’ for a fire regime of ignition & ‘push’ for a fire regime
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