Note: This serves as the technical note for the Grassland/Shrubland fire frequency indicator.

The Data

The USDA Forest Service has an active program of research into fire and fuels management, including development of tools for assessing fire risk due to changes in fire frequency. In particular, the Fire Regimes for Fuels Management and Fire Use project, which began in 1997, involves mapping and characterization of presettlement natural fire regimes and current vegetation conditions and development of an index of departure for use in national- level fire management planning.

As part of this program, the Forest Service has developed estimates of presettlement fire frequency, using biophysical information, preexisting remote-sensing products, and expert knowledge about disturbance and successional processes and developed stylized successional pathways for unique combinations of presettlement fire regime and potential natural vegetation. These estimates can be found at http://www.fs.fed.us/fire/fuelman/firereg.htm.

Additional information on this procedure may be found in Schmidt et al. (in press).

However, historic fire return intervals, based on tree ring scars and similar site measurements, have not been determined for the majority of the United States. The research project described above has developed estimates of fire return intervals by inference from existing vegetation. Essentially this involves assumptions about the fire return interval required to permit a certain vegetation type to develop. While these are valuable estimates, they are based on a significant amount of expert knowledge and modeling, rather than being relatively direct measurements of fire return frequency, and thus were not appropriate for inclusion in this report.

References

Cissel, J.H., F.J. Swanson, and P.J. Weisburg. 1999. Landscape management using historical fire regimes: Blue River, Oregon. Ecological Applications 9:1217–1231.

Knapp, P.A. 1997. Spatial characteristics of regional wildfire frequencies in intermountain west grass-dominated communities. Professional Geographer 49:39–51.

Knapp, A.K., J.M. Briggs, D.C. Hartnett, and S.C. Collins, eds. 2000. Grassland dynamics. New York: Oxford Univ. Press. Sauer, C.O. 1950. Grassland climax, fire and man. Journal of Range Management 3:16–21.

Schmidt, K.M., J.P. Menakis, C.C. Hardy, D.L. Bunnell, N. Sampson, J. Cohen, and L. Bradshaw. In press. Development of coarse-scale spatial data for wildland fire and fuel management. General Technical Report RMRS-GTR- CD-XXX. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Swanson, F.J., J.A. Jones, D.O. Wallin, and J.H. Cissel. 1993. Natural variability—implications for ecosystem management. In M.E. Jensen and P.S. Bourgeron (eds.), Eastside Forest Ecosystem Health Assessment. Vol. II: Ecosystem management: Principles and applications. Portland OR: U.S. Forest Service.

Wallin, D.O., F.J. Swanson, and B. Marks. 1994. Landscape pattern response to changes in pattern generalization rules: Land use legacies in forestry. Ecological Applications 4:569–580.