Jennifer Adams Krumins will present the Department of Biological Science seminar with a talk entitled, "Mechanisms of Rhizosphere Decomposition and Feedbacks to Primary Productions".

Classical food web theory once limited to trophic relationships has evolved to embrace a variety of network interactions such as mutualisms and indirect effects.  The process of decomposition is one of the most critical network interactions that indirectly influences all ecosystem functioning, especially primary production.  Likewise, the degree to which decomposition and subsequent mineralization of nutrients indirectly and positively affect primary production is determined by the elemental compositions or quality (C:N:P) of the decomposer and decomposed.  I have developed a mathematical model that simulates the balance between trophic efficiency, plant elemental quality and nutritive feedbacks through decomposition in the rhizosphere.  That model shows that the efficiency of a herbivore determines whether or not plant material is processed within the herbivore or the microbial decomposer pool.  The elemental quality of the herbivore or the microbial decomposers will determine whether or not nutrients are mineralized and made available for primary production.  Recently, together with collaborators, I have modified the model to also account for seasonal variation in plant elemental quality.  That adapted model allowed us to resolve the decomposer pool by showing that seasonal variation in plant quality can affect whether fungal or bacterial decomposers dominate in the rhizosphere.  A deeper understanding of microbial decomposers in soil will inform ecosystem and community ecology as well as current challenges like mitigating carbon storage and managing agriculture