Optimal growth schedule of a perennial plant

Y. Iwasa, D. Cohen

Research output: Contribution to journalArticlepeer-review

125 Citations (Scopus)

Abstract

The optimal growth schedule of a deciduous perennial plant is studied theoretically, making 3 basic assumptions: 1) the daily net photosynethetic rate of a plant increases but saturates with the size of the production part (vegetative organs working for photosynthesis), 2) the production part is discarded at the end of the growing season, but it may be rebuilt at the beginning of the next season; and 3) the plant maximizes the lifetime reproductive investment by choosing both the growth schedule within each season and the resource allocation between reproduction for the year and storage for the next season. Analysis showed 3 basic results. 1) The annual life cycle is optimal under low storage efficiency, low habitat reliability, low growth rate, and a short growing season. 2) Under any other conditions, perennial growth is optimal. During years in which the final amount of resources is smaller than a critical value, the plant remains immature and saves all of the resources for the next season. If it becomes larger, the plant invests the excess in reproductive activities and repeats the same growth schedule thereafter (steady state). 3) Reproductive effort of a mature plant is high for an annual, is lowest for a perennial just above the threshold for the perennial growth pattern, increases as the length of the season increases, and in a very productive habitat may even exceed the level for an annual. The ratio of the plant size established by stored material to the maximum plant size decreases with the length of the growing season. Growth patterns and leaf phenology of many deciduous plants indicate that the nonlinearity of photosynthetic rate as a function of the size of the production part is important. For a case with nonlinear photosynthesis but without an upper limit to the leaf expansion rate, a plant's optimal phenology, if normalized by size, can be parameterized by productivity (maximum relative growth rate multiplied by a season's length) and stability (annual survival multiplied by storage efficiency). Timing of the cessation of leaf production within a season by a small immature plant is determined by productivity (occurring later in a more productive habitat). Leaf production ends earlier in the season as the plant grows. The optimal time for ending leaf production in a mature plant is controlled mainly by stability (ceasing earlier at the more stable site) and is almost independent of productivity. -from Authors

Original languageEnglish
Pages (from-to)480-505
Number of pages26
JournalAmerican Naturalist
Volume133
Issue number4
DOIs
Publication statusPublished - Jan 1 1989

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics

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