CO2 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 CO2 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 degrees C. The CO2 emission rate was measured biweekly by gas chromatography. The CO2 emission rate increased with temperature and decreased in deeper soil sublayers. Linear regression relating CO2 efflux to soil sublayer and temperature returned R-2 = 0.87. Sensitivity of organic matter decomposition to temperature was estimated as activation energy and as Q(10) coefficient, the increase in reaction rate per 10 degrees C. Activation energy was 50 kJ mol(-1), 59 kJ mol(-1) and 71 kJ mol(-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(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.