U.S. Joint Fire Science Program


Date of this Version


Document Type



Fire Science Brief, Issue 126, January 2011


US government work.


Many populations of Baker and Macnab cypress are dying without signs of regeneration. The Forest Service is currently implementing controlled burning across a range of vegetation types in northern California, but because there is little information about how such treatments will affect rare, endemic plant communities, cypress stands have been excluded from such treatments. However, these fire-adapted species cannot survive extended periods of fire exclusion. To effectively manage the cypress and prevent further decline of the species, land managers need information on factors that promote cypress regeneration. The objectives of this study were to (1) determine if fire is indeed necessary to restore cypress, (2) determine if prescribed burning can successfully promote cypress regeneration and, if so, (3) determine what fire severity and fire return interval promote cypress regeneration. The data confirm that fire is critical to regeneration of both Baker and Macnab cypress stands. It is therefore important to return fire to the stands— either through wildfires or through controlled burning. Because of hesitation to allow wildfires to burn, encroachment of other conifer species has resulted in the deterioration of adult trees presently seen in many of the stands. Thus, a reconsideration of wildland fire use and controlled burning are needed. Typical controlled burns are generally carried out at low intensity, yet high intensity is needed to achieve sufficient Macnab and Baker cypress regeneration rates, so experimental forms of prescribed burning will likely be necessary to promote suffi cient regeneration to restore cypress populations. Regarding fire return interval, the results show that if fires occur too frequently, stands may not have matured enough to produce a suffi cient amount of seeds to regenerate and are thus subject to risk of “immaturity.” On the other hand, results show no evidence of risk for either cypress species growing too old and thereby outliving the possibility of regeneration. So as long as the stand remains healthy, it should be allowed to live longer to achieve greater seedbank potential. But for mature stands that face risk of death due to unfavorable site conditions, it is recommended that fire be introduced as soon as possible.