Allocation dilemmas in plants

Jan Kozlowski (September 30, 2010)

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There are annual and perennial plants; perennials may reproduce once in life (semelparity, monocarpic perennials) or repeatedly (iteroparity). Perennial herbs lose virtually all vegetative parts but storage organs before winter, whereas shrubs and trees retain large part or even most of vegetative mass. Theory of optimal resource allocation helps to predict important features of the two strategies. Annuals must chose the best time during a year for the switch from vegetative to generative growth and "decide" about the proportion of seeds germinating in the next season and amounting to a seed bank. Semelparous perrenials must choose the year for flowering. Iteroporous perennials must choose when to allocate assimilated resources to growth and when to reproduction, and they must optimize investments to storage. If perennials reproduce vegetatively, they must also optimize division between generative and vegetative reproduction. Grazers are everywhere, but defense is costly: plants must optimize the intensity of protection. Understanding these complex problems an