A tabular model for ecological succession of the autogenic, autotrophic type

Ecosystem characteristic
Trend in ecological development  early stage to climax
Or
youth to maturity
or
growth stage to steady state

Community structure
Species composition
Changes rapidly at first, then more gradually
Size of individuals
Tends to increase
Number species of autotrophs
Increases in primary and often early in secondary succession; may decline in older stages as size of individuals increases
Number species of heterotrophs
Increases until relatively late in the sere
Species diversity
Increases initially, then becomes stabilized or declines in older stages as size of individual increases
increases
Nonliving organic matter
increases

Energy flow (community metabolism)
Gross production (P)
Increases during early phase of primary succession; little or no increase during secondary succession
Net community production (yield)
decreases
Community respiration (R)
Increases
P/R ratio
P>R to P = R
P/B ratio
Decreases
B/P and B/R ratios (biomass supported/ unit energy)
increases
Food chains
From linear chains to more complex food webs

Biogeochemical cycles
Mineral cycles
Become more closed
Turnover time
increases
Role of detritus
increases
Nutrient conservation
increases


Natural selection and regulation

Growth form
From r – selection (rapid growth) to K – selection (feedback control)a
Quality of biotic components
increases
niches
Increasing specialization
Life cycles
Length and complexity increases
Symbiosis (living together)
Increasingly mutualistic
entropy
decreases
informationb
increases
Overall stability
increases

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