A method for quantifying changes in the epicuticular wax structure of Norway spruce needles

A method for quantifying in the epicuticular wax structure of spruce needles (Picea abler) has for the scanning electron microscope. This evaluation system, based on a five-point only the epistomatal waxes of current-year needles. Two criteria, the different crystal wax forms and the amount of changed wax as a percentage of the total stomatal area have been used for classification. Statistically significant results (accuracy below +/- 10% at 5% error level) were obtained under the following conditions. Mixed needle samples were taken from two adjacent trees per site. These were in a dominant and predominant social position in the stand. The needles were collected from the 7th whorl of sun crowns exposed to all wind directions. The wax quality was determined by evaluating three stomata per needle. One stoma was investigated at the needle base, one in the middle and the third at the apex of the needle. 24 needles were evaluated per site. SEM-Investigations of needle waxes of 25 Austrian forest sites with no local emission source (background sites) showed, that the mean wax quality ranged from 1.6 to 4.1, according to this classification method. Stepwise multiple regression analyses with site characteristics and element contents of the needles (nutrient elements, heavy metals) confirmed correlations between the wax quality and the manganese- and sulphur-content of the needles and also the average degree of crown defoliation.