Changes in Carbon following Forest Soil Transplants along an Altitudinal Gradient

Abstract

Using a simple case study approach, this research tested the hypothesis that soil organic carbon (C) concentrations would decline when mineral soils from cool, nitrogen (N)–rich, high‐elevation (>1400 m) forests were transplanted to warmer, N‐poor, low‐elevation (∼545 m) forests. Two short‐term (<5 year) experiments were performed in the Great Smoky Mountains National Park (Tenn./N.C.) in the southern Appalachian Mountains. In the first experiment, C concentrations in whole soils, particulate organic matter (POM), and mineral‐associated organic matter (MOM) declined significantly (P 0.001) when soils from a high elevation site (1H) were transplanted to a low‐elevation site (1L). In the second experiment, there was a significant (P  0.05) decline in POM C concentrations when high elevation soils (2H) were moved to a lower elevation (2L) as well as declines in whole soil C concentrations that were significant at P  0.10. In both cases, reciprocal transplants of low elevation soils to high elevations resulted in no detectable change in soil C concentrations. Warming of higher quality soil organic matter (whole soil C‐to‐N ratio <20) resulted in greater soil C loss. Consistent with prior predictions, the results suggest that a future warmer and drier climate may cause losses of forest soil C at high elevations in the southern Appalachian Mountains.

Keywords:

• Climate change
• elevation gradient
• soil carbon
• soil C‐to‐N ratio
• warming

ACKNOWLEDGMENTS

This research was sponsored by the U.S. Department of Energy, Office of Science, Biological and Environmental Research/Terrestrial Carbon Processes Program under contract DE‐AC05‐00OR22725 with Oak Ridge National Laboratory (ORNL), managed by UT‐Battelle, LLC. I thank Bonnie Lu (retired) and Deanne Brice (ORNL) for their valuable technical assistance. The submitted manuscript has been authored by a contractor of the U.S. government under contract DE‐AC05‐00OR22725. Accordingly, the U.S. government retains a nonexclusive, royalty‐free license to publish or reproduce the published form of this contribution, or to allow others to do so, for U.S. government purposes.