International Research Fellowship Program: Herbivorous Nematodes and the Microbial Loop: Unraveling Below-ground Mechanisms Affecting Plant Production

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0758674KruminsThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support an eighteen-month research fellowship by Dr. Jennifer A. Krumins to work with Dr. Wim H. van der Putten at the Netherlands Institute of Ecology in Heteren, The Netherlands.Nutrient cycling in soil food webs is critical to plant production and plant community diversity because direct and indirect interactions between soil organisms (especially the microbial loop) potentially affect nutrient availability to plants. Most soil research studies nutrient cycling carried out by microbes in isolation from other organisms in soil food webs associated with plant roots. In nature, a mixture of positive and negative feedbacks between plants and soil organisms drive nutrient cycling and ultimately, plant production and community structure. For instance, root grazing by nematodes can negatively affect plants (a direct effect), but consumer waste associated with grazing may positively affect plants through nutrient enrichment (an indirect effect). The goal of this fellowship project, developed in collaboration with Dr. van der Putten, is to integrate these indirect (nutrient conversion) and direct (herbivorous animals) interactions in the soil community. In doing this, they will not only resolve important below-ground mechanisms that determine plant production, but will also contribute to an important growing body of theory describing the relative importance of positive versus negative interactions between plants and soil biota. The experiment proposed here will simultaneously answer the following important questions: 1.) Will root herbivory indirectly and positively affect microbial loop biomass and activity? 2.) Will enhanced microbial loop activity positively influence plant production? They will address these questions in greenhouse experiments using potted dune grasses. To test the direct effect of grazing, the PI will create an herbivorous nematode density gradient and measure microbial loop response in function and community composition and plant response in below and above ground biomass. Through collaboration with Dr. Peter C. de Ruiter and the host, the data acquired in these experiments will be used to develop mathematical models predicting plant responses to indirect, positive feedbacks.