Developing FCCS Fuelbeds for the Angora Fire Region

Project Description

The Fuel Characteristic Classification System was used to develop a set of past, current, and future fuelbeds for the Lake Tahoe Basin Management Unit—information that will enable managers to better plan restoration and wildlife habitat projects and account for potential fire hazard, smoke from wildland fire, and carbon.

Purpose and Scope

The Fuel Characteristic Classification System was used to develop a set of past, current, and future fuelbeds for the Lake Tahoe Basin Management Unit—information that will enable managers to better plan restoration and wildlife habitat projects and account for potential fire hazard, smoke from wildland fire, and carbon.

Methods

Fuelbed Identification and Development

A team of fire ecologists and fire and fuel experts were gathered to list a set of important fuelbed types for the Lake Tahoe Basin Management Unit (LTBMU). A fuelbed pathway (similar to a successional forest pathway, but for fuelbeds as they change over time) was created for each fuelbed type. The fuelbed pathways were developed from consensus of land managers and the project leads based on (1) fuelbed types that were important, (2) years for a fuelbed to change significantly, (3) common management and natural change agents that occur in the LTBMU. The pathways highlighted fuelbeds which needed to be constructed to represent major forest types, natural succession, common management activities, and natural disturbances over time. In addition, 20 fuelbeds were added to the fuelbed list that did not fall within the key fuel types identified by the LTBMU managers, but would allow a more complete assignment of fuelbeds to vegetation classes found in the LTBMU.

Fuelbeds provided in the  Fuel Characteristic Classification System (FCCS) library (Ricarrdi et al. 2007, http://www.fs.fed.us/pnw/fera/fccs/fuelbed_references.shtml) or from other projects (i.e., Okanogan/Wenatchee National Forest project and central Oregon project, http://www.fs.fed.us/pnw/fera/fccs/downloads.shtml#sf) were used as starting points for creating LTBMU fuelbeds. Plant association and forest community guides (Fites 1993; Smith 1994; Potter 1994), photo series (Ottmar et al. 1998, Ottmar et al. 2000a, Ottmar et al. 2000b, Ottmar et al. 2007), inventory databases (http://www.fs.fed.us/pnw/fera/fccs/fuelbed_references.shtml), experimental results (Stephens and Moghaddas 2005) and expert opinion were used to modify the fuelbed descriptions and adjust fuelbed inputs, including loading, depths, percentage cover, and species to represent the fuelbeds identified in the pathways and that fell outside the six important fuelbed types. Field data from the LTBMU was not collected for building the fuelbeds because resources and time were limited. However, the fuelbeds provided by the FCCS library and other national forest projects were developed from measured data acquired through scientific literature, regional databases, or actual field measurement.

Fuelbed Characteristics

Some fuelbed characteristics such as woody fuel loading, litter depths, and shrub heights are assigned to each fuelbed during the fuelbed building process. However, other fuelbed characteristics use input variables to calculate other characteristics that were not measured. Fuelbed characteristics, including shrub loading, litter loading, and carbon by fuelbed strata, categories, and subcategories, were calculated for each fuelbed using the FCCS. Fire Behavior FCCS version 2.1 was used to calculate (1) surface fire behavior, crown fire, and available fuel potentials; (2) reaction intensity, rate of spread, and flame length (Sandberg et al. 2007a; Sandberg et al. 2007b) for each fuelbed at three moisture scenarios (low, medium, and high), and (3) midflame windspeeds (0, 3, and 7 mph) and slopes (0, 30, and 70 percent). These environmental variables and slopes were selected by LTBMU managers and scientists to provide results at a wide range of conditions. Suggested crosswalks to the original Fire Behavior Prediction System (Albini 1976, Andrews et al. 2005, Rothermel 1972) and standard fuel models (Scott and Burgan, 2005) were also determined at three moisture scenarios (low, medium, high), midflame windspeeds (0, 3, and 7 mph) and slopes (0, 30, and 70 percent).

Fuelbed Handbook

General information on the fuelbed types, fuelbed pathways and their related fuelbeds, fire potentials, surface fire behavior prediction, and fire behavior fuel model crosswalk were compiled into the Lake Tahoe Basin Fuelbed Pathway Handbook. Fuelbed types and pathway information are summarized in schematics and tables that include the fuelbed names, description, age class, and any management actions or natural change agents associated with each fuelbed. All fuelbed outputs are presented in summary tables. Representative photos for many fuelbeds were collected and provided in the handbook to illustrate general structural features of the fuelbeds only and were not intended to represent actual species composition or fuel loadings.

Fuelbed Map

To map FCCS fuelbeds we used CALVEG data for the Lake Tahoe Basin Management Unit (U.S. Forest Service 2008). The vegetation type (regional dominance type) and overstory tree size class were used to create unique classes. These unique vegetation classes matched closely with the fuelbed type, age, and characteristics of the pathways and fuelbeds, so a simple crosswalk was created. Once a fuelbed map was produced, it was discovered that there were more vegetation classes than fuelbed types developed for the basin and the map coverage was less than 90 percent. To improve map coverage, 20 additional fuelbeds outside the fuelbed types were constructed and added to the map to achieve a +99.5 percent fuelbed coverage of the Lake Tahoe Basin Management Unit.