Ceanothus: Taxonomic patterns in life history responses to fire

Premise Ceanothus (Rhamnaceae) is a large genus of shrubs that dominate California chaparral and are resilient to fires. Persistence is ensured by resprouting and/or seedling recruitment from dormant seed banks. Some species do both and others, the obligate seeders, are entirely dependent on seedlin...

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Bibliographic Details
Published in:American journal of botany 2024-11, Vol.111 (11), p.e16434-n/a
Main Authors: Keeley, Jon E., Thomas Parker, V., Zedler, Paul H., Brandon Pratt, R.
Format: Article
Language:English
Subjects:
California
California Floristic Province
Ceanothus
Ceanothus - physiology
Cerastes
Chaparral
Climate prediction
Documents
Fires
Forest & brush fires
Geographical distribution
Life history
lignotubers
Miocene
obligate seeding
postfire resprouting
Rhamnaceae
Seed banks
Seeders
Seedlings
Seedlings - growth & development
Seeds
Speciation
Species
Wildfires
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Summary:Premise Ceanothus (Rhamnaceae) is a large genus of shrubs that dominate California chaparral and are resilient to fires. Persistence is ensured by resprouting and/or seedling recruitment from dormant seed banks. Some species do both and others, the obligate seeders, are entirely dependent on seedling recruitment. The distribution of these two modes within the genus is poorly documented. Methods We used all available publications that document species responses to fire and filled most gaps in the literature based on extensive field studies of more than 60 recent wildfires in California. Results The genus is divided into two subgenera, Ceanothus and Cerastes. Ceanothus is widely considered to comprise mostly resprouting species and Cerastes to consist of only obligate seeders. The subgenus Ceanothus includes resprouting species throughout their range from the eastern United States and Midwest to western United States. Within the California Floristic Province (CFP), a few species are unique in producing massive lignotubers that develop from repeated fires; however, within the CFP, the majority of species in this subgenus do not resprout and are obligate seeders. Two have disjunct subspecies that are facultative seeders or obligate seeders. Conclusions Previously, speciation in this genus was contended to have occurred in the late Miocene within the CFP. The syndrome of obligate seeding is most strongly represented in this region, and we hypothesize that evolution of this syndrome was a response to increased predictability of fire driven by the Mediterranean climate and the long interval between fires.
ISSN:0002-9122
1537-2197
1537-2197
DOI:10.1002/ajb2.16434