Soil carbon pools of six ecological regions of the United States

Mineralisable soil organic carbon (SOC) pools vary with ecosystem type in response to changes in climate, vegetation and soil properties. Understanding the effect of climate and soil factors on SOC pools is critical for predicting change over time. Surface soil samples from six ecoregions of the United States were analyzed for permanganate oxidizable C (KMnO4-C) and mineralizable C pools. Variations of SOC ranged from 7.9 mg g−1 (Florida site) to 325 mg g−1 (Hawaii site). Mineralisable C pools and KMnO4-C were highest in soils from the Hawaii site. Mean annual precipitation explains SOC and resistant C pool variations. Clay content was related to mineralisable active C pools and bacterial abundance. Mean annual precipitation and clay content are potential variables for predicting changes in SOC pools at large spatial scales.