The Two-Way Median Fit: A Sensitive Statistical Procedure to Detect Response of Trees to Fertilization

Authors: Gerig, Thomas M.; Schreuder, H. T.; Crutchfield, D. M.; Wells, C. G.

Source: Forest Science, Volume 24, Number 3, 1 September 1978 , pp. 358-362(5)

Publisher: Society of American Foresters

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Abstract:

Data from a factorial nitrogen and phosphorus fertilization experiment conducted during a 5-year period in a productive 19-year-old loblolly pine plantation were analyzed by univariate and multivariate analyses of variance and by a new, exploratory data analysis technique called the two-way median fit. The variable of interest was stand basal area. The multivariate analysis of variance showed a small but significant nitrogen effect. The univariate analysis of variance showed that nitrogen increased cumulative growth in the first 2 years but had no effect in the later years. The two-way median fit indicated that nitrogen stimulated growth most in the first 2 years but nitrogen plus phosphorus stimulated growth best over the 5 years of the study. Phosphorus applied alone seemed to have no impact on growth. Forest Sci. 24:358-362.

Keywords: Multivariate analysis of variance; initial basal area; critical levels; productive site

Document Type: Journal article

Affiliations: 1: Principal Soil Scientist, USDA Forest Service, Southeastern Forest Experiment Station, Research Triangle Park, North Carolina 27709

Publication date: 1978-09-01

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