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Abstract

The parameter Q(10) is commonly used to express the relationship between soil CO₂ efflux and soil temperature. One advantage of this parameter is its application in a model expression of respiration losses of different ecosystems. Correct specification of Q(10) in these models is indispensable. Soil surface CO₂ efflux and soil temperature at different depths were measured in a 21-year-old Norway spruce stand and a mountain grassland site located at the Experimental Ecological Study Site Bily Kriz, Beskydy Mts. (NE Czech Republic), using automated gasometric systems. A time-delay and goodness-of-fit between soil CO₂ efflux and soil temperature at different measuring depths were determined. Wide ranges of values for the time-delay of CO₂ efflux in response to temperature, Q(10) and the determination coefficient (R-2) between CO₂ efflux and temperature were obtained at the both sites. The values of Q(10) and the CO₂ time-delay increased with depth, while the R-2 of the CO₂-temperature relationship significantly decreased. Soil temperature records obtained close to the soil surface showed the highest values of R-2 and the lowest value of the time-delay at both sites. Measurement of soil temperature at very shallow soil layer, preferably at the soil surface, is highly recommended to determine useable values of Q(10). We present a new procedure to normalize Q(10) values for soil temperatures measured at different depths that would facilitate comparison of different sites. [References: 34]