PARENT SESSION
Oral Session #93: Forest Carbon Dynamics: Soils and litter.
Presiding: J. Ward
Thursday, August 8. 1:00 PM to 3:45 PM. Grand Ballroom Central, Radisson.
Soil carbon character and content in three old growth forests.
Magrini, Kimberly*,1, Evans, Robert1, Hoover, Coeli2, Looker, Michael1, 1 National Renewable Energy Laboratory, Golden, CO2 USDA Forest Service Northeastern Research Station, Irvine, PA
ABSTRACT- As interest in the mitigation of greenhouse gas emissions grows, the need for better information on soil organic matter (SOM) becomes more urgent. Soils are one of the most significant terrestrial carbon sinks, and understanding the content and structure of SOM contained in old growth forest soils provides a baseline for comparing the impact of forest management practices on soil quality and soil organic carbon pools. Our objective is to move beyond traditional measures of SOM, using pyrolysis molecular beam mass spectrometry (py-MBMS), for the rapid assessment of SOM. Py-MBMS can quickly provide information on the chemical nature of SOM, allowing the development of SOM quality based on the relative amounts of recent and older SOM pools. We used py-MBMS to assess the SOM contained in three old-growth forests, primarily hemlock dominated, located in Pennsylvania, New Hampshire, and Wisconsin. Samples, taken at three depth increments, were analyzed with py-MBMS in about three minutes. Factor analysis of the mass spectra showed that the samples can be distinguished by both depth and forest location. Though the SOM content is approximately similar for each site, differences do exist: the 0-5 cm samples from Pennsylvania and New Hampshire are more similar than those from Wisconsin. In the 10-20 cm increment, the Pennsylvania and Wisconsin sites have more similar chemistry than New Hampshire. Recent biomass is characteristic of shallow samples and more aromatic species, representative of more degraded biomass, are found in the deeper samples. We will discuss similarities and differences in SOM chemistry found in these old growth soils.
KEY WORDS: pyrolysis mass spectroscopy , soil organic carbon, rapid soil analysis, forest soil characterization