Tracheid length prediction in Pinus palustris by means of near infrared spectroscopy:: the influence of age

The prediction of tracheid length using near infrared (NIR) wavelengths can provide either useful or misleading calibrations depending on the context. This can happen since tracheid length is not directly related to the absorbance at any wavelength but is instead the result of a secondary correlation with some unknown chemical constituent. In this work, the effect of tree age and height on NIR predictability was investigated since tracheid length and chemistry may vary as a function of location within the tree. It was found that tracheid length predictability did not change with height but decreased with age. As a result, predicting tracheid length regardless of age was good (R-2 = 0.72) while predictability holding age and height constant was mostly low to moderate with with the exception of rings 1 and 4 which was quite strong.