Evidence for Losses From Strongly Bound SOM Pools After Clear Cutting in a Northern Hardwood Forest

Abstract

Forest soils in the northeastern United States store considerable amounts of carbon (C). With the increasing utilization of biomass as a “C-neutral” form of energy in the United States, these forests are susceptible to clear cutting and large losses of soil organic matter (SOM) to the atmosphere as carbon dioxide (CO₂). The relative stability versus susceptibility of SOM to degradation can be approximated, in part, through the strength of organo-mineral interactions, that is, the strength of binding between SOM and mineral surfaces in the soil. This study investigated differences in SOM organo-mineral binding between northern hardwood forest stands with varying clear-cutting histories in Bartlett Experimental Forest in Bartlett, New Hampshire. Sequential chemical extractions were performed to quantify SOM storage in organo-mineral pools of various binding strength. In this case study, soils from Mature forest stands stored significantly more SOM in strongly mineral-bound and stable C pools than soils from Cut stands did. Differences in the relative distribution of C in organo-mineral pools in Mature and Cut forests may inform our understanding of SOM bioavailability, microbial decomposition, and CO₂ production in ecosystems after clear cutting. These findings should contribute to discussions on long-term SOM stability in northeastern U.S. soils.