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An Evaluation of Plot Methods for Alpine Vegetation
Lee E. Eddleman, Elmer E. Remmenga and Richard T. Ward
Bulletin of the Torrey Botanical Club
Vol. 91, No. 6 (Nov. - Dec., 1964), pp. 439-450
Published by: Torrey Botanical Society
Stable URL: http://www.jstor.org/stable/2483912
Page Count: 12
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In a dry-mesic area at 11,600 feet in northern Colorado, a study was made to evaluate plot shape, size, and number for quantitative study of alpine vegetation. The plots tested were 100, 400, 800, and 1600 square centimeters in size, with rectangles, squares and one circle utilized. Placement designs were random and block random. Densities were determined for seven species, ranging from common to uncommon, and frequencies were found for all species in one plot size. Pattern was estimated by chi-square and the variance/mean ratio for the species sampled for density. Estimates of plot efficiency were based upon the time required to read the number of plots needed to obtain a 10 per cent standard error of the mean, and upon average weighted standard deviations and stability in density and frequency values. Of the various evaluations, none favored the smallest sized plots of 100 cm2. In several respects the larger plots were about equally suitable to one another, but the 1600 cm2 plots presented difficulties in knowing which individuals had been counted and also would have the unfavorable characteristic of yielding frequencies of 100 per cent for several species. Evidence from the present study tended to favor, but only very slightly, rectangles over squares. Block random design was indicated to be preferable to simple random. For an intensive study intended to provide accurate estimates for all species, rare as well as common, several hundred plots of the 400 cm2 size would be required. Reasonable accuracy for the common species, however, can be obtained with as few as 50 plots of this size; 100 plots are recommended for general studies. Five of the seven species showed mostly contagious distributions in the various plots, and two were random. The scale of pattern present was thought to be related primarily to vegetative reproduction.
Bulletin of the Torrey Botanical Club © 1964 Torrey Botanical Society