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Temporal Stability as a Density-Dependent Species Characteristic
L. R. Taylor and I. P. Woiwod
Journal of Animal Ecology
Vol. 49, No. 1 (Feb., 1980), pp. 209-224
Published by: British Ecological Society
Stable URL: http://www.jstor.org/stable/4285
Page Count: 16
You can always find the topics here!Topics: Species, Statistical variance, Population density, Moths, Density, Animal ecology, Population estimates, Density estimation, Extinct species, Population mean
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(1) Accumulated annual totals of adults (Nt) of ninety-seven species of aphids and 263 species of moths were measured over a period of at least 6 years, at eighteen and fifty-three sites respectively, in Great Britain and adjacent mainland Europe. (2) Annual variance (St2) of Nt is here taken as a measure of the stability of the population density of a species at a site (Nt alpha mt). (3) Stability was found to be a systematic non-linear function of mean population density (mt) at the different sites over the whole area sampled (more than 2000 km2). (4) Just as spatial stability (Ss2) is a power function of mean population density over an area at all times (ms), so it is concluded that temporal stability is a power function of mean population density (St2 = amtb) over time at all places [Note: equation omitted. See the image of page 209 for this equation.]. (5) Log mean density accounts for a very large proportion of log temporal stability (more than 90% in most species); the parameter b is highly specific and therefore largely independent of the local environmental variables, including parasites, predators and available resources, which differ between sites. (6) We conclude that, unlike mean density, stability is not a function of extrinsic mechanisms, which must differ widely and unsystematically in space and time, but is an intrinsic property of the behaviour of the species. (7) The population density is estimated from flying adults and the problems of obtaining adequate density estimates for this kind of investigation are briefly considered.
Journal of Animal Ecology © 1980 British Ecological Society