Dynamics of an Invasive Non-Native Species and its Biological, Physical, and Human Impacts: Spartina Alterniflora on the Pacific Coast

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ABSTRACTHastings, Alan M. , Susan L. Ustin, Edwin D. Grosholz, and Donald R. StrongDEB 0083583"Dynamics of an invasive non-native species and its biological, physical, and human impacts: Spartina alterniflora on the Pacific coast"The PIs propose an integrative study of the dynamics of the invasive species, Spartina alterniflora (cordgrass), including a core mathematical/conceptual model, physical and biological feedbacks, and a study of the impacts on non-commercial human values. The core model is termed a "local-state, regional-state" model and the crucial innovation is the use of discrete time and continuous states and explicit inclusion of stochastically based on integro-difference equations, yielding substantial mathematical and computational advantages over reaction diffusion models. The state of the invasion will be a function of position along the shore, tidal height, age of Spartina, and densities of other species or human valuations in the system, and time. ENSO fluctuations, feedbacks, and non-reciprocal effects are included in the framework. Hypotheses concerning the biological bases of positive feedbacks, Allee effects, and density dependence will be tested experimentally and results integrated into the model.Parameterization will be from a rich set of historical records and from remotely-sense images, references with GPS. Mixture analysis with data will inform the model of biochemical conditions of the cordgrass. Experiments will give data on demography, clonal growth, seed set, tide flow profile, sediment erodability, and shear stress. Sediment accretion will be quantified. Intensively studied sites will be extrapolated to the entire estuary using NASA's ASTER sensor on the Terra satellite. A map will be built of Pacific estuaries using daily MODIS satellite images. Food web and community effects will be studies experimentally. The ultimate faunal effects on the invasion will be measured in passerines and rallids. These observations will be combined with the overall model to develop long term prediction of the impact of Spartina on birds. Finally, these invasions are ideal for studying non-commercial values lost to the changes caused by Atlantic cordgrass. Integrating the valuation with the model will provide one of the first rigorous studies of invasive species on the value of ecosystem services.