Needle surface characteristics and element contents of Norway spruce in relation to the distance of emission sources

Needle surface characteristics, i.e., epistomatal wax quality, occurrence of dust, microorganisms and gypsum-crystallites investigated under a scanning electron microscope (SEM), and element contents of current-year spruce needles (Picea abies (L.) Karst.) were analyzed at sites with different pollution levels (background, industry, conurbation area, motorway) in Austria. The wax quality as evaluated by a recently developed quantification method, was significantly poorer at all sites with a higher pollution level. Dust particles and gypsum-crystallites were only detected on needles from sites located in the vicinity of pollutant sources. No significant differences between the sites were found for the occurrence of microorganisms on stomata. Significantly lower needle contents of the elements N, P, Ca, K, Mg, S, Cu and Zn were found at background sites. Several nutrient elements were detected in the dust layer on needle surfaces from sites influenced by pollutant sources. The evaluation of the nutritional status of spruce stands using the element contents of unwashed needle material in areas influenced by emissions was discussed in this respect.