LIFE EXPECTANCY OF SPRUCE NEEDLES UNDER EXTREMELY HIGH AIR-POLLUTION STRESS - PERFORMANCE OF TREES IN THE ORE MOUNTAINS

Photosynthetic performance of Norway spruce needles [Picea abies (L.) Karst.] was measured over a 1-year period. The trees grew in an area o f heavy air pollution and forest decline on a mountain ridge in the ea stern Ore Mountains (Czech Republic). Photosynthetic capacity, as well as light use efficiency, decreased dramatically with time, starting i n July (2 months after bud-break) to finally reach zero (respiration o nly) by February of the following year. Two months later all needles f rom upper crown parts were shed. Needles from lower crown parts, on th e other hand, were undamaged. The chlorophyll and Mg content decreased transiently during the cold season, with Mg reaching deficiency thres holds during winter. However, total sulfur, as well as organic and sul fate S increased with time. The increase was higher in needles from th e upper parts of the crown, which were exposed to windy air throughout the year, than in the lower parts of the crown, which were covered by grass during summer and by snow during most of the winter.