The net ecosystem exchange (NEE) of CO2 between the biosphere and the atmosphere is defined as the balance between fluxes associated with photosynthetic assimilation by the foliage and respiratory effluxes from autotrophic and heterotrophic processes. Canopy photosynthesis is predominantly controlled by the amount of absorbed solar radiation. In the presented poster we show that it is important to discriminate between the direct and diffuse components of incoming radiation. The investigated Norway spruce forest (20-year-old) is situated in the Beskydy Mts. (49°33´N, 18°32´E, NE of the Czech Republic) on the slope (11-16°) with SSW orientation on the area of 6.2 ha. The stand density is 2600 trees per hectare (hemi-surface leaf area index ca. 11 m2 m-2), mean (+- standard deviation) tree height and stem diameter at 1.3m are 8.5 +- 0.1 m and 10.1 +- 0.1 cm, respectively.

The net ecosystem exchange (NEE) of CO2 between the biosphere and the atmosphere is defined as the balance between fluxes associated with photosynthetic assimilation by the foliage and respiratory effluxes from autotrophic and heterotrophic processes. Canopy photosynthesis is predominantly controlled by the amount of absorbed solar radiation. In the presented poster we show that it is important to discriminate between the direct and diffuse components of incoming radiation. The investigated Norway spruce forest (20-year-old) is situated in the Beskydy Mts. (49°33´N, 18°32´E, NE of the Czech Republic) on the slope (11-16°) with SSW orientation on the area of 6.2 ha. The stand density is 2600 trees per hectare (hemi-surface leaf area index ca. 11 m2 m-2), mean (+- standard deviation) tree height and stem diameter at 1.3m are 8.5 +- 0.1 m and 10.1 +- 0.1 cm, respectively.