DISSERTATION RESEARCH: Dynamics of labile organic matter fractions in arctic soils

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The proposed doctoral dissertation research will determine the extent to which soil aggregates, a foundation of soils, provide stabilization for soil organic matter (SOM) in the Arctic. Warming has been linked to changes in carbon cycling in the Arctic. Cold temperatures and anoxic conditions inhibit microbial activity and reduce decomposition, resulting in an accumulation of carbon-rich organic matter, straining an already nitrogen-limited system. Nutrient additions have changed the plant community and depleted soil carbon; however, mechanisms behind carbon loss are not understood. It is not known which OM fractions are most susceptible to degradation in Arctic soils, and 2) where are they located within the soil matrix. These factors are important to understanding mechanisms behind carbon loss in Arctic soils, which may be due, in part, to shifts in the physical stability of soil aggregates. In other words, soils with greater proportions of macroaggregates contain more carbon.Soils have been collected from long-term nutrient addition experiments at the Arctic LTER site on the Alaskan North Slope, and were separated into four size classes of aggregates. These aggregates will be separated into sub-structural elements as well as free OM, which will reveal if SOM is protected within aggregates and which fractions are susceptible to degradation. The project will also link current conceptual models of soil carbon stabilization to the Arctic. The graduate student will interact with the K-12 community by providing research opportunities for teachers through existing workshops, internships, and a Teacher-in-Residence program.