Changes in the content and constituents of the cuticular wax of Picea abies (L.) Karst. in relation to needle ageing and tree decline in five European forest areas

Cuticular wax composition of healthy and and declining mature Norway spruce trees Picea abies (L.) Karst.] was investigated in five European forest areas. The amount of extracted wax and the content of alkanes and secondary alcohols were analysed as a function of the factors sample area (five areas, detailed below), needle age (current year to 2 years) and decline class (Class O to Class 2). Using a GC-MS, alkanes from C₂₀ to C₃₁ and the following alcohols were quantified: 10-nonacosanol, 5,10-nonacosandiol, 4,10-nonacosandiol and the triterpenol 24-methylenecycloartanol. According to our results, the total wax content as well as the alkane and alcohol content of waxes show a large variation corresponding to sample area and needle age. Ageing caused a highly significant increase in alkane content and a highly significant decrease in total wax and alcohol content. The decline class significantly influenced only the content of the long chain alkane C₃₁ (increase), the secondary alcohol 10-nonacosanol (decrease), and the triterpenic alcohol (decrease). Total wax weight was not influenced by tree damage. Thus, according to our results, needle ageing and progressive tree damage are correlated to different changes in the examined parameters.