Statistical comparison of foliage spectral and biochemical measurements on an example of Norway spruce stands in the Ore Mountains, Czech Republic
Abstrakt
The physiological status of vegetation and changes can be monitored by means of biochemical analysis of collected samples as well as by means of spectroscopic measurements either on the leaf level or on the canopy level. The present study focuses on the statistical comparison of three data sets collected from selected Norway spruce forest stands in the Ore Mountains, Czech Republic.
The data sets comprised i) biochemically retrieved photosynthetic pigments and water content of samples collected from from three different vertical levels of a tree crown and the first three needle age classes, ii) the spectral reflectance of the same shoot samples measured with an ASD Field Spec 4 Wide-Res spectroradiometer equipped with a plant contact probe, iii) an airborne hyperspecral image acquired with an Apex sensor. The data sets cover two areas (western and central) in the Ore Mountains that were affected differently by acid deposits in the 1970's and 1980's.
A one-way analysis of variance, Tukey's honest significance test, hot spot analysis and linear regression were applied. The results revealed a generally low correlation between the photosynthetic pigments, water content and spectral measurement.
The results of the ANOVA showed significant differences between model areas only in the case of the leaf compound data set. Differences between the stands on various levels of significance existed in all three data sets and are discussed.
The study also proved that the vertical gradient of the biochemical and biophysical parameters in a tree crown play a role when the optical properties of the forest stands are modelled. It is possible to conclude that the differences in the physiological conditions of stands observed in high extent in 1998 still were slightly detectable in 2013, though the physiological conditions levelled up.
From the point of view of optical properties, the differences between the areas are not significant on laboratory or image reflectance spectra.