Pulse-dynamic and monotonic decline patterns of soil respiration in long term laboratory microcosms

Carbon dioxide from soil respiration is a key source of atmospheric CO2 and a major component of the global carbon cycle. However, the temporal pattern of soil respiration is not well understood and even wrongly modeled. In a 360-day laboratory experiment, we investigated temporal patterns of soil respiration and microbial carbon availability using five soils taken from five altitudinal zones on a temperate Mountain. We found two distinctive patterns in soil respiration and carbon availability among the five soils: a new pulse-dynamic pattern for soils taken from middle altitudinal zones, and the commonly reported pattern of monotonic decline for other soils. Our redundancy analysis further showed that soil texture plays a major role in determining the occurrence and magnitude of the pulse-dynamic pattern. The new pulse-dynamic pattern challenges the commonly held static view of soil organic carbon mineralization, and has crucial implications for modeling soil carbon in terrestrial ecosystems.