Ecological Archives E087-087-A4

Brett A. Melbourne and Peter Chesson. 2006. The scale transition: scaling up population dynamics with field data. Ecology 87:1478–1488.

Appendix D. Spatial variance components for periphyton.

TABLE D1. Spatial variance components for ln(periphyton density), standard error of the variance component, stratum variances, effective degrees of freedom (brackets indicate the random-effects model that includes the reach stratum), P values for the variance components, and the percentage contribution of each scale to the total observed spatial variation.

      

Strata (scale)

SE

Strat. Var

df

P

% Var


Stream

0.0043

0.0436

1.7319

1

0.50

0.63

Reach

0

-

-

(4)

0.86

0.00

Site

0.1006

0.0997

1.4783

18 (14)

0.0004

14.72

Plot

0.1360

0.1087

0.9034

19.98

0.0169

19.89

Rock

0.1483

0.0952

0.5003

38.57

0.1183

21.69

Sample

0.2944

0.0671

0.2944

38.46

 

43.07


† , where i indexes scales (Underwood and Chapman 1996).
‡ The estimated variance component at the reach scale was -0.033. This small, negative variance component was assumed equal to zero (difference from 0, P = 0.86, likelihood ratio test) and all the variance components in the table were estimated omitting the reach term from the random-effects model (Payne 2002).

LITERATURE CITED

Payne, R. W. 2002. The Guide to Genstat, Part 2 Statistics. VSN International, Oxford, UK.

Underwood, A. J. 1996. Spatial patterns of variance in density of intertidal populations. Pages 369–389 in R. B. Floyd, A. W. Sheppard, and P. J. De Barro, editors. Frontiers of Population Ecology. CSIRO Publishing, Melbourne, Australia.



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