Population dynamics of a monocarpic thistle: Simulated effects of reproductive timing and grazing of flowering plants

Ramula, S (2008) Population dynamics of a monocarpic thistle: Simulated effects of reproductive timing and grazing of flowering plants. Acta Oecologica, 33 2: 231-239. doi:10.1016/j.actao.2007.11.005


Author Ramula, S
Title Population dynamics of a monocarpic thistle: Simulated effects of reproductive timing and grazing of flowering plants
Journal name Acta Oecologica   Check publisher's open access policy
ISSN 1146-609X
1873-6238
Publication date 2008-03-01
Sub-type Article (original research)
DOI 10.1016/j.actao.2007.11.005
Volume 33
Issue 2
Start page 231
End page 239
Total pages 9
Place of publication Issy les Moulineaux, France
Publisher Elsevier Masson
Language eng
Abstract In monocarpic plants, which die after flowering once, the timing of reproduction plays an important role. The optimal time for reproduction is when reproductive output and survival are maximized. This optimum may be altered by herbivores that consume reproductive plants of different sizes disproportionally. I examined plant survival, flowering probability, reproductive output and the probability of becoming grazed in relation to plant size in two populations of the short-lived monocarpic herb Cirsium palustre. Moreover, I simulated the consequences of changes in reproductive timing and grazing preference for population dynamics. Plant survival, flowering probability and reproductive output tended to increase with plant size, whereas the probability of becoming grazed was unaffected by plant size. According to the stochastic simulations, intense grazing would have been required to significantly reduce the stochastic population growth rate (logls) and therefore, the observed levels of grazing had no impact on logls in the study populations. Stochastic simulations conducted with selective grazing focusing on either early or late flowering plants and with different reproductive timings revealed that the grazing of early flowering plants had a constant effect on logls despite the proportions of early and late flowering plants in the population, suggesting that there is no optimal time for reproduction. The grazing of late flowering plants reduced logls with delayed reproduction, favouring reproduction early in the life cycle.
Keyword Demography
Grazing
Herbivory
Matrix population model
Monocarpy
Population growth rate
Reproductive timing
Stochastic simulation
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Biological Sciences Publications
 
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Created: Thu, 03 Sep 2009, 20:14:33 EST by Mr Andrew Martlew on behalf of School of Biological Sciences