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Citation:
USDA, Forest Service, Missoula Fire Sciences Laboratory. 2018. Fire regimes of California chaparral communities: Information from the Pacific Southwest Research Station and LANDFIRE. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Missoula Fire Sciences Laboratory (Producer). Available: www.fs.usda.gov/database/feis/fire_regimes/CA_chaparral/all.html [].

The Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture, provides a review and synthesis of the historical range of variability for three chaparral community types common in California: Adenostoma chaparral dominated by chamise and/or redshank; mixed chaparral; and montane chaparral (Estes 2016 [2]). Chamise-redshank chaparral occurs on low foothills; buckbrush often codominates in chamise chaparral. Mixed chaparral occurs on foothills and is typically codominated by ceanothus, manzanita, and/or scrub oak species. Montane chaparral occurs at midelevations and is typically codominated by ceanothus and manzanita species (review by [2]). See table 2 for scientific names of plants and for links to FEIS Species Reviews.

Figure 1. Types of California chaparral.
Chamise chaparral in San Benito County, CA. Photo ©Neal Kramer, used with permission.	Redshank chaparral in Riverside County, CA. Public domain image by Anthony Baniaga.
Mixed chaparral (sticky whiteleaf manzanita-canyon live oak-toyon-gray pine) in Columbia, CA. USDA, Forest Service photo by Janet Fryer.	Montane chaparral (greenleaf manzanita-prostrate ceanothus, in center foreground) surrounded by montane mixed-conifer forest (background) in Tuolumne County, CA. USDA, Forest Service photo by Janet Fryer.

The fire regime of these chaparral communities is that of mostly stand-replacement crown fire at moderate intervals. Estimated historical (1880s-1940s) fire-return intervals for chamise-redshank and mixed chaparral range from 30 to 90 years, with a MFRI (mean fire-return interval) of 55 years. Estimated range for montane chaparral is 15 to 50 years, with a MFRI of 27 years. Determining fire-return intervals difficult for chaparral because little evidence of past stand age and stand conditions remain after stand-replacement fire. Estimates of historical fire-return intervals in chaparral are based on fire scars on remnant trees adjacent to chaparral, historical written accounts, cover type maps, and photographs. (review by [2]).

Two patterns of departure from the natural range of variation are evident for fire in California chaparral. Where chaparral is interspersed within or adjacent to coniferous forest, decades of fire exclusion has resulted in successional replacement of chaparral vegetation with conifers on some sites. However, succession after large, stand-replacement fires in coniferous forests has increased the extent of chaparral vegetation on other sites (review by [2]).

Estimated fire regime characteristics are available from LANDFIRE succession modeling of Biophysical Settings (BpS). Table 1 summarizes these estimates for the BpSs in California chaparral communities. Figure 2 shows where they occur. Table A1 lists the BpSs and the results of LANDFIRE succession modeling for each BpS in California chaparral communities.

Figure 2. Land cover distribution of California chaparral communities based on the LANDFIRE Biophysical Settings (BpS) data layer [4]. Numbers indicate LANDFIRE map zones. LANDFIRE did not map every BpS in this group. Click on the map for a larger image and zoom in to see details.

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