PRODUCTION ACTIVITY OF MOUNTAIN CULTIVATED NORWAY SPRUCE STANDS UNDER THE IMPACT OF AIR-POLLUTION .2. VERTICAL-DISTRIBUTION OF PHOTOSYNTHETIC ACTIVITY IN THE STAND CANOPY

Investigation of photosynthetic activity of Norway spruce (Picea abies (L) Karst.) was carried out in the Moravskoslezske Beskydy Mts. The aim of the present study was designated to identify vertical distribution and differences of photosynthetic activity within canopy of two stands with different silvicultural activity. The investigation was based on an analysis of relationship between CO2 uptake rate and photon flux density of photosynthetically active radiation. The stand structure has a large influence on radiation conditions within the stand canopy and on differentiation of photosynthetic activity (PA). Vertical distribution of PA divides the stand canopy into three different crown layers. There am significant differences between PA of the lower crown layers and the upper ones. Thinning is responsible for differences in the portion of the lower crown layer in the whole canopy photosynthetic activity. Thus the effect of thinning was documented on an increase in PA portion of the lower crown layer on the whole canopy PA in comparison to control (unthinned) stand. Ecophysiological investigation of photosynthetic activity response to silvicultural activity has given an important information which is necessary for ecologically based forest management of Norway spruce stands under air pollution impact.