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This article in JEQ

  1. Vol. 27 No. 2, p. 293-298
    Received: Nov 25, 1996

    * Corresponding author(s): ecassell@zoo.uvm.edu


Modeling Phosphorus Dynamics in Ecosystems: Mass Balance and Dynamic Simulation Approaches

  1. E. A. Cassell *,
  2. J. M. Dorioz,
  3. R. L. Kort,
  4. J. P. Hoffmann,
  5. D. W. Meals,
  6. D. Kirschtel and
  7. D. C. Braun
  1. School of Natural Resources, Univ. of Vermont, Burlington, VT 05405;
    Inst. de Limnologie, Inst. Natl. de la Recherche Agronomique, 74203 Thonon Les Bains, FRANCE;
    Natural Resources Conserv. Serv., USDA, Winooski, VT 05404;
    Dep. of Botany, Univ. of Vermont, Burlington, VT 05405.



Phosphorus (P) export from agriculture is a major cause of eutrophication in many lake ecosystems. Human activity, hydrology, and physicochemical and biological processes that store, transform, and transport P, define P export patterns over time and space. We suggest that an ecosystem paradigm is useful to holistically view P dynamics within complex watersheds. An ecosystem model of a dairy agricultural system was created within a hierarchical compartment-flux structure of a conceptual watershed ecosystem. Mass balance calculations with our Agriculture Ecosystem model (AEP model) describe P dynamics for the farm system, which are driven by the amount of P stored in agricultural soils and system management practices. Longterm P dynamics respond predominately to human interventions in watersheds and define conditions for future generations. Model simulations suggest that long-term environmental protection programs should incorporate the notions of P sustainability into management decisions. Dynamic simulation modeling is a valuable paradigm for understanding how complex watersheds process P and for developing management perspectives and public policy to achieve goals of environmental quality as well as economic and resource sustainability.

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