Plant size and spatial pattern in a natural population of Myosotis micrantha

Authors

  • Chester Wilson,

    1. Department of Ecology and Evolution, State University of New York at Stony Brook, Stony Brook, NY 11794-5245 USA
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    • 2

      Current Address: Department of Biology, University of St. Thomas, Mail # 4404, 2115 Summit Avenue, Saint Paul, MN 55105-1096 USA;

  • Jessica Gurevitch

    Corresponding author
    1. Department of Ecology and Evolution, State University of New York at Stony Brook, Stony Brook, NY 11794-5245 USA
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*Author for correspondence; Fax +1 516 632 7626; E-mail JGURVTCH@LIFE.BIO.SUNYSB.EDU

Abstract

Abstract. We examined spatial distributions and plant sizes along a transect through a natural population of a winter annual, Myosotis micrantha. A size hierarchy existed, as indicated by high values of Gini coefficients of inequality for plant mass and correlated measures. Plants with no immediate conspecific neighbors were larger than plants with one or more near neighbors, suggesting that competition from near neighbors depressed plant size. However, there was strong positive spatial autocorrelation in plant size: large plants were associated with large neighbors and small ones with small neighbors. Plant size was also positively correlated with the combined biomass of near neighbors. The population formed a two-phase mosaic of patches of relatively large plants alternating with patches of smaller plants. The data suggest that individual plants compete with conspecifics, but the effects of competition are symmetrical. The most likely explanations for this spatially structured size hierarchy are variation in plant density, patchy distribution of resources, or a combination of the two.

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