PARENT SESSION
Session #22: Observation, manipulation, experimentation and extrapolation: Limitations and opportunities in ecosystem-level studies. Organized by: R.H. Gardner and J.E. Petersen.
Friday, August 10, 2001. Lecture Hall

Identifying scale-dependent limitations for the extrapolation of experimental results across time and space.

GARDNER, ROBERT¹, SCHEURER, DAVID¹, ¹

ABSTRACT- Recent reviews have revealed a broad awareness of the importance of scale-dependent relationships in natural and experimental systems. Nevertheless, insights regarding the importance of scale have been driven more by observation and theory than by experimentation. Therefore, we developed a mesocosm-scale pelagic model, embedded within a spatial framework, to evaluate the effect of spatial and temporal variation in physical forces and biological interactions on our ability to predict across scales. Ecosystem parameters for the pelagic model were derived from a series of mesocosm experiments while the spatial framework was used to simulate scale-dependent changes in biological and physical forcings to the model. Results of model simulations were then compared with independently collected and spatially extensive measures of variation in chlorophyll concentrations within the Chesapeake Bay. Systematic variation of model parameters then allowed the relative contribution of physical versus biological factors to be quantified as a function of scale. This "spatial and temporal decomposition" provides a rigorous means of evaluating the range over which experimental results may be reliably extrapolated.

KEY WORDS: scale-dependent, extrapolation, pelagic model, chlorophyll