vol. 158, no. 6 the american naturalist december 2001 The Bamboo Fire Cycle Hypothesis: A Comment Sonali Saha * and Henry F. Howe † Department of Biological Sciences, University of Illinois at Chicago, Chicago, Illinois 60607 Submitted January 24, 2000; Accepted December 14, 2000 Keywords: bamboo, critique, delayed reproduction, fuels, India, mast flowering, monocarpic, seedling recruitment, wildfire. The bamboo fire cycle hypothesis proposed by Keeley and Bond (1999) argues that lightning-ignited wildfire has syn- chronized flowering and recruitment of bamboos through- out Asia. They argue that mast flowering followed by mass mortality leads to fuel-load accumulation, encouraging ig- nition by lightning strikes that results in complete con- sumption of litter and dead stalks, which both enhances bamboo regeneration from seeds and seedlings and si- multaneously suppresses neighboring vegetation. They further argue that such fires create the conditions for monocarpic (semelparous, or breeding only once) repro- duction of clones at long intervals, a feature that distin- guishes woody bamboos from other bamboos and from the vast majority of higher plants. We do not find the hypothesis compelling. Multiple causation is the rule in ecological and life-history expla- nation (Quinn and Dunham 1983), and it is always pos- sible that fire has played a role in the evolution of some bamboo taxa somewhere. But we see no evidence that fire has played a central role in the evolution of mast flowering or monocarpy in general or in our area of direct experience in South Asia, where 70 of 72 woody bamboo species are monocarpic and mast flowering (eight species are strictly synchronous; see Gadgil and Prasad 1984; Kelly 1994). We do not see evidence that other plant taxa are fire adapted in habitats where mast-flowering, monocarpic bamboos thrive nor do we find the logic of the argument convincing on its merits. Aspects of bamboo biology remain puzzling, but we are forced to conclude that whatever resemblance * E-mail: ssaha1@uic.edu. † E-mail: hfhowe@uic.edu. Am. Nat. 2001. Vol. 158, pp. 659–663.  2001 by The University of Chicago. 0003-0147/2001/15806-0010$03.00. All rights reserved. highly seasonal monsoon forests of Asia have to fire-prone and fire-adapted ecosystems of the world is superficial and that such other explanations for mast fruiting as seed- predator satiation still explain the evidence better than the bamboo fire cycle hypothesis. Bamboo Geography and Evolution Woody bamboo species belonging to the subtribe Bam- buseae are characterized by long flowering cycles with monocarpic reproduction (reproduction once, followed by death) that separates them from herbaceous bamboos and the vast majority of higher plants (Soderstrom 1981). Ex- ceptions occur, with some herbaceous genera (e.g., Olyra) showing mast flowering and monocarpy and with some woody bamboo species from the Americas and Asia show- ing monocarpy but also continuous flowering with only a small percentage of individual clumps in bloom at one time (Janzen 1976; Gadgil and Prasad 1984; Judziewicz et al. 1999). The bamboo fire cycle hypothesis hopes to ex- plain woody species that flower and seed synchronously and die shortly thereafter. Available molecular and morphological evidence indi- cates that woody bamboo species evolved from herbaceous allies in humid forests of the Southern Hemisphere during the Cretaceous (70–140 m.y.b.p.; Clayton 1981; Hsiao et al. 1999; Judziewicz et al. 1999). Extant herbaceous bam- boos occur in New World rain forests. The basal lineage within the herbaceous bamboos is Buergersiochloa, which is restricted to the rain forests of New Guinea (Judzeiwicz et al. 1999). In the Old World, woody bamboos are present in tropical nondeciduous, temperate nondeciduous, semi- deciduous, and monsoon forests of Southeast Asia, Africa, Madagascar, and tropical North Australia. The center of woody bamboo diversity in the Paleotropics is in tropical and temperate nondeciduous forests of Southeast Asia. Diversity is low in Africa and Australia. In the New World, the highest diversity and greatest degree of endemism are in the Atlantic humid and littoral forests of Brazil, the north and central Andes, Mexico, and the Guyanan high- lands (Soderstrom 1988; Clark 1990, 1995). Some woody bamboo species are present in dry and fire-prone habitats in the southwestern United States, the Brazilian cerrado,