INFLUENCE OF ALTITUDE, SAMPLING YEAR AND NEEDLE AGE CLASS ON STRESS-PHYSIOLOGICAL REACTIONS OF SPRUCE NEEDLES INVESTIGATED ON AN ALPINE ALTITUDE PROFILE

The aim of the presented study was to characterize the physiological s tate of spruce needles from an alpine profile depending on altitude (9 70-1420 m above sea level) and needle age class (current year needles, one-year-old needles) during two consecutive years by investigating c omponents of the antioxidative scavenging system (water extractable th iols, ascorbic acid, total peroxidase). The chlorophyll content was me asured as a non-specific indicator of the general plant condition. Wit h the exception of thiols the one-year-old needles always had higher n eedle contens of antioxidants and chlorophylls and the means of thiols and chlorophylls were significantly higher in the second sampling yea r. A more or less continous increase of antioxidants and a decrease of chlorophylls with increasing altitude was observed from the middle el evations (1140-1240 m a.s.l.) up to the highest site near the timberli ne (1420 m a.s.l.) and was interpreted as a response of the needles to increased oxidative stress due to the more uncomfortable environmenta l conditions at these elevations. However, high levels of antioxidants near the valley bottom (970-1050 m a.s.l.) also indicated an enhancem ent of the detoxification system and rather low chlorophyll levels (me ans of one-year-old needles <1100 mu g/g dw) probably reflected high e nvironmental impact on the trees at these sites.