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Synchrony and asynchrony: observations and hypotheses for the flowering wave in a long-lived semelparous bamboo

Franklin, Donald C. (2004). Synchrony and asynchrony: observations and hypotheses for the flowering wave in a long-lived semelparous bamboo. Journal of Biogeography,31(5):773-786.

Document type: Journal Article
Citation counts: TR Web of Science Citation Count  Cited 30 times in Thomson Reuters Web of Science Article | Citations
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ISI LOC 000220855800006
Title Synchrony and asynchrony: observations and hypotheses for the flowering wave in a long-lived semelparous bamboo
Author Franklin, Donald C.
Journal Name Journal of Biogeography
Publication Date 2004
Volume Number 31
Issue Number 5
ISSN 0305-0270   (check CDU catalogue open catalogue search in new window)
Scopus ID 2-s2.0-2142721016
Start Page 773
End Page 786
Total Pages 14
Place of Publication Oxford, Great Britain
Publisher Blackwell Publishing
Field of Research 0403 - Geology
0406 - Physical Geography and Environmental Geoscience
0603 - Evolutionary Biology
HERDC Category C1 - Journal Article (DEST)
Abstract Aim (1) To describe the spatio-temporal patterns of mass-flowering and die-off in a long-lived, semelparous, clumping bamboo, Bambusa arnhemica, at landscape and local scales. (2) To discuss causal processes in the flowering patterns of semelparous bamboos. Location The entire range of B. arnhemica, in the monsoonal, tropical, north-west of the Northern Territory of Australia, mostly along watercourses. Methods Landscape-scale flowering patterns were assessed by a combination of air, boat and ground survey in each year from 2000 to 2002. Areas that flowered prior to 2000, and those in which no flowering occurred, were also recorded, and historic records collated. At local scales, initiation of flowering, rates of die-off, and subsequent germination densities of seedlings were quantified by ground-based counts. Results After an estimated 40-50 years of vegetative development, B. arnhemica flowered, seeded prolifically, then died. Flowering occurred synchronously within patches ranging from 0.002 to 3200 km(2). One or more patches flowered in successive years from 1996 to 2002, forming a temporally-structured but spatially-chaotic flowering wave that affected c. 80% of the population. Synchronous flowering took the form of a flowering distribution in which over 95% of clumps within a patch initiated flowering in a central year, most of the remainder flowering the year before or after. Along the Daly River, an exception was observed in which 56% of clumps flowered in the peak year. Seedling densities were three orders of magnitude greater under clumps that flowered in the central rather than the leading year of the flowering distribution. Main conclusions Synchrony is argued to be the primal state in semelparous bamboos, promoted by intense selection acting on a endogenous (genetic or biological) clock whose influence largely overrides that of the environment. A flowering wave may develop within an initially synchronous population when stochastic events interact with the biological clock without permanently altering the clock setting, producing an off-set patch. Off-set groups may only survive if sufficient individuals are off-set by the same amount at the same time and in the same vicinity so as to produce a new synchronously-flowering patch. This could be driven by two processes. Inter-year climatic variation may alter the biological clock's perception of time, producing off-sets at local or regional scales or even affecting entire populations. Severe environmental pressures may also force one-off changes to flowering schedules, as suggested by a severe flood event prior to flowering on the Daly River. A dynamic hypothesis for a wider range of bamboo flowering patterns is proposed in which synchronous flowering is fragmented and disrupted over time but renewed by allochronic speciation and dispersal.
Keywords bambusa arnhemica
gregarious semelparity
mast fruiting
biological clock
stabilizing selection
bamboo flowering wave
reproductive isolation
incipient speciation
mast-fruiting dipterocarpaceae
south-central chile
periodical cicadas
allochronic speciation
evolutionary ecology
predator satiation
tree regeneration
wind pollination
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