Abstract
Branch CO2 efflux of Norway spruce tree [Picea abies (L.) Karst.] was measured in ten branches at five different whorls during the growing season 2004 (from June till October) in campaigns of 3–4 times per month at the Beskydy Mts., the Czech Republic. Branch CO2 efflux was measured using a portable infrared gas analyzer (LI-6250, LI-COR, Inc., USA), operating as a closed system. Branch woody-tissue temperature was measured continuously in 10-min intervals for each sample position during the whole experiment period. On the basis of relation between CO2 efflux rate and woody-tissue temperature, a value of Q10 and of normalized CO2 efflux rate (E10–CO2 efflux rate at 10°C) was calculated for each sampled position. Estimated Q10 values ranged from 2.12 to 2.89, and E10 ranged from 0.41 to 1.19 μmolCO2m−2s−1. Differences in branch CO2 efflux were found between orientations, east-side branches presented higher efflux rate than west-side branches. The highest branch CO2 efflux rate values were measured in August and the lowest in October, which corresponds with woody-tissue temperature and growth processes during these periods. Branch CO2 efflux was significantly and positively correlated with branch position within canopy and woody-tissue temperature. Branches from the upper whorls showed higher CO2 efflux activity and seasonal dynamics than branches from the lower whorls.
Published Version
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