Biogeochemical Budget Models
LOICZ- Biogeochemical Modeling Node
Under LOICZ I, the goal was to compile regional carbon/nitrogen/phosphorus data and budget models for numerous coastal areas of the world that can be used to produce global syntheses models of their flux in the coastal zone.
LOICZ II continues to support the approach, to refine the methodology, and to begin to apply it to other coastal management questions. The node is currently housed at the Baltic Nest Institute (http://nest.su.se/), a program of the Stockholm Resilience Centre (http://www.stockholmresilience.org/).
The two current contacts for the Biogeochemical Modeling Node are:
|Dennis Swaney||Fred Wulff|
|Department of Ecology and Evolutionary Biology, Cornell University||Department of Systems Ecology Stockholm University|
|E309 Corson Hall Ithaca, NY 14853, USA Phone: +1-607- 255 3572||Phone +46-8-164250 Fax: 46-8 158 417|
BACKGROUND BUDGETARY MODELS IN LOICZ
In science, models are tools that help us conceptualize, integrate, and generalize knowledge. Natural systems such as ecosystems are usually very complex, and models vary greatly in the degree of simplification away from that complexity. "Budget models" are simple mass balance calculations of specific variables (such as water, salt, sediment, CNP, etc.) within defined geographic areas and over defined periods. Usually budget models are built to aggregate the many small individual pieces of a system into smaller sets of pieces which are similar to one another. Thus, all plant species in an ecosystem might be aggregated into "primary producers." Some grouping will occur for almost any model. As one applies a single model across a range of systems, the value of such groupings becomes readily apparent. For some purposes it may be adequate to group all organisms within an ecosystem into the "net biogeochemical reactions" which occur within the system.
One can proceed from these simple, highly aggregated, models to more complicated models which describe specific processes (e.g., primary production as a function of light; sediment transport as a function of river flow, etc.). Many such process models may be further combined into an integrated system model. However, in general, the more complex the model structure, the less statistically robust is the statistical output.
A working group was convened at the Bedford Institute of Oceanography (Halifax, Canada) in September 1995 to draft initial guidelines for modeling within the context of LOICZ. Those guidelines appeared as Gordon et al. (1996): LOICZ Biogeochemical Modeling Guidelines. The interested reader is referred to that document for more detail. Gordon et al. recommended the following activities to initiate modeling within LOICZ:
- Construct many local budget models, following a budgeting procedure which is as internally consistent as possible within the limitations of available data.
- Compare these budget models to seek patterns of similarity or difference in material fluxes.
- Use accepted statistical procedures to extrapolate the flux calculations from budgeted regions of the coastal zone to unbudgeted regions, in order to improve our understanding of material fluxes to and from the coastal zone of the world’s oceans.