Type Conversion - The Impact of Excessive Fire
What is Type Conversion?
A good summary of the literature concerning chaparral type conversion: Park, I.W. and G.D. Jenerette. 2019. Causes and feedbacks to widespread grass invasion into chaparral shrub dominated landscapes. Landscape Ecology 34: 459-471. Also see our Desert Fires page for details concerning type-conversion in desert ecosystems.
The Science is Clear Chaparral is Threatened by High Fire Frequency
The 2019 Cave Fire - type conversion in process
Ten years is not enough time for chaparral shrub species to grow to maturity and produce enough seed (the natural fire return interval for chaparral is 30 - 150 years or more). Such a short fire return interval will compromise the re-burned habitat and will likely lead to type conversion to non-native grasses and weeds which pose a greater fire danger.
Fortunately, much of the northern part of the fire area had remained unburned for at least a few decades. The various native plant species in these areas will explode with life over the next several years.
A Sample of Type Converted Areas in California
Resources on Type Conversion and Invasive Weeds
Fire frequency impacts non-sprouting chaparral shrubs in the Santa Monica Mountains of southern California. Jacobsen A.L., S.D. Davis, and S.L. Fabritius. 2004. In Ecology, Conservation and Management of Mediterranean Climate Ecosystems. Eds. M. Arianoutsou and V.P. Papanastasis. Millpress, Rotterdam, Netherlands.
Fire management impacts on invasive plants in the western United States. Keeley, J.E. 2006. Conservation Biology 20: 375-384.
Alien plant dynamics following fire in Mediterranean-Climate California Shrublands. Keeley, J.E., M. Keeley, C.J. Fotheringham. 2005 Ecological Applications 15: 2109-2125.
Fuel breaks affect nonnative species abundance in California plant communities. Merriam, K.E, J.E. Keeley, J.L Beyers. 2006. Ecological Applications 16: 515-527.
Chaparral Fuel Modification: What Do We Know - and Need to Know? J.E. Keeley. 2005.
Fire and invasive plants on California landscapes. Keeley, J.E., J.F. Franklin, C. D’Antonio. 2011. In D. McKenzie et al. (eds.), The Landscape Ecology of Fire, Ecological Studies 213. Springer Science + Business Media B.V.
Papers relating to the importance of long fire return intervals in chaparral.
Fire suppression impacts on postfire recovery of Sierra Nevada chaparral shrublands. Keeley, J.E., A.H. Pfaff, and H.D. Safford. 2005. International Journal of Wildland Fire 14: 255-265.
Are long fire-free periods needed to maintain the endangered, fire-recruiting shrub Arctostaphylos morroensis (Ericiaceae)? Odion, D., and C. Tyler. 2002. Conservation Ecology6: 4.
Fire, soil heating, and the formation of vegetation patterns in chaparral. Odion, D.C., and F.W. Davis. 2000. Ecological Monographs 70: 149-169.
Quote from Odion and Davis. 2000. "At the interface between human development and chaparral vegetation, desirable management from biological and slope stability perspectives argues not for relatively short rotation hazard reduction burning, but for improving characteristics of the built environment (defensible space, structures, landscaping, safe evacuation means, etc.), in efforts to reduce the perils of fire posed by living near chaparral."