Symposium 4: Ecological Complexity and Sustainability
Organized by: E Rykiel and T Allen
Tuesday, August 5. 8:00 AM to 11:30 AM, SITCC Oglethorpe Auditorium.

Dimensions of ecosystem complexity: heterogeneity, connectivity, and history.

Cadenasso, Mary*,1, Pickett, Steward1, Grove, J. Morgan2, 1 Institute of Ecosystem Studies, Millbrook, NY2 USDA Forest Service, South Burlington, VT

ABSTRACT- Biocomplexity metaphorically invokes connectivity among organisms and their environment. Ecology is poised to move beyond metaphor towards a rigorous definition of biocomplexity and model testing. We define biocomplexity as the degree to which ecological systems comprising biological, social and physical components incorporate spatially explicit structure, organizational connectivity, and historical contingency through time. These three dimensions of biocomplexity — heterogeneity, connectivity, and history — will be explored along axes of increasing complexity. Basing the description of spatial heterogeneity on patch or continuous quantification, complexity of spatial structure increases as quantification move from simple discrimination of patch types and the number of each type to assessment of configuration and the change in the mosaic through time. Organizational complexity reflects the increasing connectivity of the basic units that control system dynamics. At the simple end of the axis, the functional connectivity between units is low, and the processes within a unit are determined by structures or other processes within that unit. At the highest level of complexity along this axis units in a mosaic interact through fluxes of energy, matter, organisms, or information, and the structure and dynamics of the mosaic can be altered by those fluxes. Temporal relationships in the system exist beyond direct contemporary ones. The influence of legacies, the existence of lagged effects, and the presence of slowly appearing indirect effects constitute increasing temporal complexity. Simplicity is the null point on each axis of complexity. A practical goal and motivation for understanding the dimensions of complexity is to discover the simplest models and analyses capable of effective explanation.

Key words: coupled systems, patch dynamics, biocomplexity, interdisciplinary