CO[sub.2] Emissions in Layered Cranberry Soils under Simulated Warming

Sanding to bury the overgrowth of uprights and promote new growth results in alternate sand and organic sublayers in the 0-30 cm layer of cranberry soils contributing to global carbon storage. The aim of this study was to measure CO[sub.2] emission rates in cranberry soil sublayers under simulated warming. Soil samples (0-10, 10-20 and 20-30 cm) were incubated in jars for up to 105 days at 10, 20 and 30 °C. The CO[sub.2] emission rate was measured biweekly by gas chromatography. The CO[sub.2] emission rate increased with temperature and decreased in deeper soil sublayers. Linear regression relating CO[sub.2] efflux to soil sublayer and temperature returned R[sup.2] = 0.87. Sensitivity of organic matter decomposition to temperature was estimated as activation energy and as Q[sub.10] coefficient, the increase in reaction rate per 10 °C. Activation energy was 50 kJ mol[sup.−1], 59 kJ mol[sup.−1] and 71 kJ mol[sup.−1] in the in the 0-10, 10-20 and 20-30 cm sublayers, respectively, indicating higher molecular-weight compounds resisting to decomposition in deeper sublayers. The Q[sub.10] values were significantly higher (p < 0.01) in the 10-30 cm (2.79 ± 0.10) than the 0-10 cm (2.18 ± 0.07) sublayers. The 20-30 cm sublayer where less total carbon was stored was the most sensitive to higher temperature. Cranberry soils could be used as sensitive markers of global warming.