Changes in Carbon following Forest Soil Transplants along an Altitudinal Gradient

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 (1400m) forests were transplanted to warmer, N-poor, low-elevation (545m) 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.