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Correlated Changes in Plant Size and Number in Plant Populations

J. White and J. L. Harper
Journal of Ecology
Vol. 58, No. 2 (Jul., 1970), pp. 467-485
DOI: 10.2307/2258284
Stable URL: http://www.jstor.org/stable/2258284
Page Count: 19
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Correlated Changes in Plant Size and Number in Plant Populations
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Abstract

The 3/2 power law, established by Yoda et al. (1963) and which relates the number of surviving plants in a population undergoing self-thinning to their mean dry weight, has been confirmed and extended to several other species. Root and shoot components of plant yield appear to follow the same law. Stands of the same species starting growth simultaneously at different densities are shown to follow a common thinning line, the stands of highest density thinning first. Varying light regimes appear to affect the constant of the w = Cp-3/2 equation (where w is mean plant weight and p the corresponding density) but not the -3/2 gradient. The `arbitrary standards' of foresters in constructing yield tables coincide closely with the law also. A possible alternative derivation of the law is recorded based on distance to nearest neighbour measurements. The assumption sometimes made that the smallest plants in a population are the first to thin, leaving the larger ones to grow more rapidly, is shown to be valid, by measurements of individual plant weight over a series of harvests.

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