?A broad distinction can be made between community ecology, which emphasizes population sizes and inter-species interactions, and systems ecology, which emphasizes nutrient and energy flows between compartments (Hagen 1989).  Nevertheless, community ecological theory also involves systems in the sense of entities that have clearly defined boundaries, coherent internal dynamics, and simply mediated relations with their external context (Taylor 1992, 2001, 383ff).  (See also the synthesis of the two schools in DeAngelis 1992 and Taylor and Post 1985.)  One needs to go beyond the dichotomy, however, to capture the range of basic impulses in studying ecological complexity evident in United States ecology from the 1950s through the mid-1980s.  These I identify in the table below, with position from left to right used to denote earlier or later emergence:

BASIC IMPULSES regarding the study of ECOLOGICAL COMPLEXITY
1. Ecosystems are complex, yet have SYSTEMIC PROPERTIES
——2. Ecosystems are complex systems of COMPARTMENTS & FLOWS of energy & nutrients
————3. Ecological complexity will be built up from BASIC, GENERAL RULES, especially about populations and their interactions
—————————–4. HIERARCHY THEORY—find natural scales of patterns and processes
————5. Important influences will be evident in PATTERNS in ecological complexity, as revealed in diversity measures or other community descriptors, or through multivariate analyses
—————————–6. Rules & generalizations may emerge from attention to actual PROCESSES through experimental manipulations or long term observations
———————————-7. PARTICULARISM—No generalizations from situation to situation
—————————–8. Ecology advances by refutation of TESTABLE HYPOTHESES

References
DeAngelis, D. L. (1992). Dynamics of Nutrient Cycling and Food Webs. London: Chapman and Hall.
Hagen, J. B. (1992). The Entangled Bank: The Origins of Ecosystem Ecology. New Brunswick, NJ: Rutgers University Press.
Taylor (1992). “Community,” in E. F. Keller and E. Lloyd (Eds.), Keywords in Evolutionary Biology.  Cambridge, MA: Harvard University Press, 52-60.
—— (2001), “From natural selection to natural construction to disciplining unruly complexity:  The challenge of integrating ecological dynamics into evolutionary theory,” in R. Singh, K. Krimbas, D. Paul and J. Beatty (Eds.), Thinking About Evolution: Historical, Philosophical and Political Perspectives.  Cambridge: Cambridge University Press, 377-393.
—— and W. M. Post (1985). A Description with Some Applications of MSNUCY, A Computer Model Combining Interspecific Interactions with Nutrient Cycling (Environmental Sciences Division Publication 2419). Oak Ridge, TN: Oak Ridge National Laboratory.

Extracted from Taylor, P.J. (2005) Unruly Complexity: Ecology, Interpretation, Engagement (U. Chicago Press).