Fire History and Fuels mapping
Fire History
Working with scientists from CAL FIRE Fire and Resource Assessment Program (FRAP) I built statewide GIS layers for historical fire perimeters and surface fuel models. In a joint project with CAL FIRE and the US Forest Service a historical fire perimeter GIS layer was digitized from a combination of paper maps, GPS perimeters, and tabular data from several federal, state, county, and local fire agencies throughout California. The data covered the period 1950 to 2001 and included USFS wildland fires 10 acres and greater, and CAL FIRE fires 300 acres and greater. BLM and NPS joined the effort in 2002, (the year I left for California State Parks) collecting fires 10 acres and greater. The California historical fire perimeters database is still maintained today.
Example fire perimeters
Fuel Model Mapping
As part of the California Interagency Fuel Mapping Group (CAIFMG) consortium I developed regional "surface fuel model" maps that span jurisdictional boundaries in California. Originally vegetation communities were mapped into the 13 Anderson Fire Behavior Fuel Models which is ground vegetative in which fire will spread. These models incorporate downed woody material (leaf litter, dead branches and logs) as well as shrub and grass communities. The amount, size and moisture content of surface fuels determines how fast a fire spreads, how hot it burns and how high its flames reach.
With the aid of FRAP fire scientists Dave Sapis and Mark Rosenberg, we developed surface fuel maps by translating vegetation information into fuel characteristics, combining them with topographic and historical fire data to form a seamless GIS fuels layers. This process, known as "crosswalking," was originally developed by the Sierra Nevada Ecosystem Project (SNEP), and translates information on plant species, crown cover and tree size into fuel behavior models. The "crosswalk" process also includes other factors, such as slope, aspect and elevation data to further refine fuel models. Finally, using fuel dynamic pathways, fire history informs areas where surface fuel characteristics changed due to past fires and subsequent regrowth.
Fire history plays an important role in modifying fuel model assignments in recently burned areas. FRAP developed a method to reflect changes in surface fuel characteristics resulting from past fires, and to account for fuel changes as burned areas re-grow. GIS analysts assign new surface fuel models based on the time since last burned. This process is called the "Fuel Dynamics Pathways".
Fuel dynamic pathways can be simple (e.g., change anything burned in the last 15 years to model 14) or they can be more complex. Below is an example of more complex "fuel dynamic pathways" for the Riverside Ranger Unit. This table shows that brush fuel models 4, 5and 6 re-grow differently on north and south slopes (Note that other fuel models are not differentiated by north and south slopes.). After a fire on south slopes, for example, fuel models 4,5 and 6 stay in model 1 for the first 3 years. After 3 years of re-growth, brush begins to return, reducing wind speeds and adding to fuel loading, producing a typical fuel model 2. Because north slopes are typically wetter, they often have less severe fire and provide for faster regrowth conditions than south slopes. In the example below, brush models on north slopes return immediately (0 -10 years) to model 5, bypassing the grass model phase experienced on south slopes.
Fuel model pathways after wildfire for the Riverside Ranger Unit.
Models 4, 5, and 6 (brush types):
South slope:
0-3 years since burn model 1
3-16 years since burn model 2
17-25 years since burn model 5
26-40 years since burn model 6
40+ years since burn model 4
North slope:
0-10 years since burn model 5
11-35 years since burn model 6
35+ years since burn model 4
Model 1 (grass):
no change due to fire
Model 2 (pine grass):
0-10 years since burn model 1
10+ years since burn model 2
Models 8,9,10,11,12,13 (timber and any slash models):
0-2 years since burn model 1
2-10 years since burn model 14 (if replanted); otherwise model 2
11-15 years since burn model 5 (due to brush component and immature trees)
16+ years since burn original model.