Canadian Forest Service Publications

An approach for the analysis of vegetation spectra using non-linear mixed modeling of truncated power spectra. 2004. Magnussen, S.; Coops, N.C.; Luther, J.E.; Carroll, A.L. Annals of Forest Science 61: 515-523.

Year: 2004

Issued by: Pacific Forestry Centre

Catalog ID: 25013

Language: English

Availability: Order paper copy (free), PDF (download)

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Analysis of vegetation spectra is often characterized by an adverse ratio of sample size to number of wavelengths. A reduction in the dimensionality of the spectra is needed to ensure consistent estimates. We propose a reduction based on a non-linear mixed modeling of power spectra transforms of truncated Fourier series representations of vegetation spectra. Two sets of foliage spectral data obtained from balsam fir (Abies balsamea) exposed to different silvicultural regimes and three eucalypt species (Eucalyptus spp.) demonstrate the method. Only the first 42 frequencies in a power spectrum contributed significantly to the variance of a spectrum. Power spectra were dominated by a small number of low frequencies; the influence of frequency was described well by an exponentiated quadratic polynomial model with significant fixed and random effects. Model parameters can be subject to physiological inference and hypothesis testing.