Temperature dependence of carbon mineralization and nitrous oxide emission in a temperate forest ecosystem

Abstract

The measurement of CO₂ and N₂O efflux from forest soils is of great importance in evaluating the role of forests as sequestering agents of atmospheric CO₂ and nitrogen. To quantify the effect of site on temperature dependence of net C-mineralization and N₂O-N emissions, three adjacent forest floors under beech, Norway spruce and mixed species stands were investigated at Solling forest, Germany, by an incubation experiment for three months. The investigated net C-mineralization and N₂O-N emissions from all forest floors exhibited an exponential increase with respect to temperature elevation. The temperature coefficient function (Q₁₀ value), was fitted to flux rates to describe the temperature sensitivity of forest floors on temperature in the range of 1–20°C. Comparing the fitted curves for temperature sensitivity of the forest floors in relation to net carbon mineralization and nitrous oxide emission rates revealed a strong positive correlation across all sites. For the whole data set of all stands, a Q₁₀ value of 1.73–2.10 for net C-mineralization and 2.81–3.58 for N₂O-N emissions per measured unit was found to describe the temperature dependency of net C-mineralization and N₂O-N efflux at experimental site. The absence of clear differences between beech and spruce in mono and mixed species cultures on temperature dependencies of net C-mineralization and N₂O-N emission rates indicated that the flux rates were not affected by species-specific differences of litter quality.

Keywords

beech / spruce / net C-mineralization / nitrous oxide emission / temperature / temperature sensitivity index (Q₁₀)