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Journal Article

Population Dynamics of the Wild Daffodil (Narcissus Pseudonarcissus): I. Clonal Growth, Seed Reproduction, Mortality and the Effects of Density

J. P. Barkham
Journal of Ecology
Vol. 68, No. 2 (Jul., 1980), pp. 607-633
DOI: 10.2307/2259425
Stable URL: http://www.jstor.org/stable/2259425
Page Count: 27
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Population Dynamics of the Wild Daffodil (Narcissus Pseudonarcissus): I. Clonal Growth, Seed Reproduction, Mortality and the Effects of Density
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Abstract

(1) The rates of reproduction and mortality, the relative importance of clonal growth and seed reproduction, and the effects of density on wild daffodil performance in clumps at Brigsteer Wood, Cumbria, are reported. (2) The fates of individually-located plants in an open and a shaded site were followed over 4-6 years. Counts were made of the numbers of capsules, seeds and seedlings, and of the proportions of plants of different `age-state'. Clumps of different size were measured to investigate the effects of density on performance and reproduction. (3) Life-table data indicated that the half-lives of adults varied from 18 to 12 years in open and shaded sites respectively. The probability that an adult will be recruited as a result of clonal growth in an open site was 4.5 × 10-2, and in a shaded site 1.5 × 10-2 and 0.087 × 10-2 per adult per year. (4) The relative proportion of adults and subadults in the population changed according to canopy conditions. Under a fully shading canopy the percentage of adults varied from 56 to 74%; in open sites the percentage of adults rose to 86% 3 years after canopy clearance, but declined to only 27% after 10 years. (5) There was a close relationship between mean dry weight per bulb at the end of the growing season and clump density, expressed as the growing-space available to bulbs. The percentage of shoots producing flowers was also positively related to growing-space. The relationship between growing-space and clonal growth in clumps was complicated by the tendency of bulb units to split up at high density. (6) It is concluded that control of the size of the adult population may be primarily through the plastic response of clonal growth to density.

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