Community structure 
Ecosystem characteristic Trends in ecological development Complex Ecosystem Theory
Species composition Changes rapidly first, slower later  
Species diversity Increases initially, then becomes stabilised or declines in old stages, as size of individuals increases

 

Total biomass (B)

Increases Larger ecosystem biomass
Non-living organic matter Increases  
Food chains From linear chains to more complex food webs Longer food chains 

 
 
 
 
 

Energy flow (Community metabolism

Ecosystem characteristic Trends in ecological development Complex Ecosystem Theory
Gross production (P) Increases during early phase of primary succession, little or no increase during secondary succession More exergy capture
Net community production (yield) Decreases  
Community respiration (R) Increases Higher transpiration in terrestrial systems

More energy flow activity within the system

P/R ratio From P > R to P = R Higher respiration
B/P and B/R ratios (Biomass supported / unit energy) Increases More effective exergy consumption
Overall efficiency of energy utilisation Increases Increases

 
 
 
 
Biogeochemical cycles 
Ecosystem characteristic Trends in ecological development Complex Ecosystem Theory
Mineral cycles Becomes more closed Less leaking (export) of material from the system 
Overall efficiency of nutrient utilisation Increases Increases
Turnover time and storage of essential elements Increases Longer cycles (Longer average cycle length)
Internal cycling Increases Turnover time of cycles or cycling rate diminishes, 

The proportions of material flowing in cycles increases.

Nutrient conservation Increases  

 
 
 
 
Natural selection and regulation 
Ecosystem characteristic Trends in ecological development Complex Ecosystem Theory
Life cycles Increasing specialisation, length and complexity More types of organisms (higher diversity)
Symbiosis Increasingly mutualistic More articulated food web, Species will occupy higher average trophic levels
Information Increases Increased organisation and diversity increase the information content of the community.

Trends in ecological development:
Odum, E. P., 1971,1997. Ecology Sinauer, Sunderland, Mass.
Odum, E. P., 1989. Ecology and Our Endangered Life-support System Sinauer Associates

Complex Ecosystem Theory:
Schneider, E.D and J.J. Kay, 1994, Life as a Manifestation of the Second Law of Thermodynamics Mathematical and Computer Modelling, Vol 19, No. 6-8, pp.25-48.