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Atmospheric factors influencing net ecosystem production of Norway spruce forest in Beskydy Mountains
Taufarová, Klára ; Havránková, Kateřina ; Czerný, Radek ; Janouš, Dalibor
Daily net ecosystem production values of Norway spruce forest at Experimental Ecological Research Site Bílý Kříž in Beskydy Mountains were estimated using eddy covariance technique. Norway spruce forest uptakes CO2 from the atmosphere during production season. During production seasons 2005-2007 mean daily net ecosystem production was 22 kg C ha-1, and mean production season duration was 240 days. During production seasons there occurred days with respiration higher than assimilation, thus the forest was source of the atmospheric carbon. There were 45, 68 and 39 days in production seasons 2005, 2006 and 2007, respectively, when the forest was carbon source. It was caused by 1) significant decrease of air temperature and low intensity of PAR at the beginning and end of production seasons; 2) low radiation in overcast days and 3) long dry period with high intensity of direct radiation and high air temperature during production seasons.
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Seasonal course of CO2 efflux in grassland and forest ecosystem in Beskydy mts
Dařenová, Eva ; Pavelka, Marian ; Acosta, Manuel ; Janouš, Dalibor
Our aim was to determine seasonal changes of CO2 efflux of the grassland and of the soil and stems in the Spruce forest at Bílý Kříž (Beskydy Mts). For elimination of the temperature dependency of CO2 efflux, standardized CO2 efflux R10 is used. Mean R10 was about 2.50, 5.0 and 0.97 umolCO2 m-2 s-1 for grassland, forest soil and stems. In grassland the R10 course did not show obvious trend. Whereas in the forest soil, the significant increase in R10 at the beginning and decrease at the end of the season occurred, but without any distinct maximum. Similar increase and decrease in R10 was observed in the stem CO2 efflux course as well. But there was a maximum in June and July. The temperature CO2 efflux sensitivity (Q10) was 3.04, 1.90 and 2.25 for the grassland, forest soil and stems. The temperature sensitivity in the forest soil increased shortly after rain. It resulted in a rapid increase in CO2 efflux of the soil as a response to rain.
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The effect of elevated air CO2 concentration on water regime and transpiration of Norway spruce
Valouch, Ludvík ; Pokorný, Radek ; Tomášková, Ivana
Under the elevated CO2 air concentration, changes in physiological processes and morphology were evident in relatively short time. Direct measurement via heat pulse method proved reduction of specific sap flux throw the stem in the first year of cultivation in elevated CO2. SSF in both treatments was comparable in the next tree years. During the sixth year of fumigation, higher transpiration rate in trees growing under elevated CO2 was recorded. It was implication of larger bearing leaf area, larger conducting vessels area on the in crosscut stems section and larger root absorbed area. Continuously sap flow measuring of sun and shaded part of the crown was found that SSF of higher crown part was higher in both treatments. Average hydraulic conductance soil-leaf (GTsa) was 1,4 times higher in sunny part of the crown than estimated for the whole crown in ambient treatment A (ambient [CO2] concentration). Difference in hydraulic conductance between the upper and lower crown part of the E treatment (doubled [CO2] concentration of A treatment) was not so pronounced.
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