Environmental Engineering Reference
In-Depth Information
Table 3.1 A “tabular model” of changes expected over ecological succession from E.P. Odum
Ecosystem attributes
Early succession
Late succession
GPP/respiration
1 Approaches 1
GPP/biomass
High Low
Biomass/energy
Low High
Net community production (NPP)
High Low
Food chains
Linear Web-like
Total organic matter
Small Large
Inorganic Nutrients
Extrabiotic Intrabiotic
Species richness
Low High
Species evenness
Low High
Biochemical diversity
Low High
Stratification and pattern
Poorly organized Well organized
Niche specialization
Broad Narrow
Size
Small Large
Life cycles
Short, simple Long, complex
Mineral cycles
Open Closed
Nutrient exchange
Rapid Slow
Role of detritus
Unimportant Important
Selection on growth form
r-Selection k-Selection
Selection on production
Quantity Quality
Symbiosis
Undeveloped Developed
Nutrient conservation
Poor Good
Stability
Low High
Entropy
High Low
Information content
Low High
GPP
gross primary production (photosynthesis),
NPP
net primary production (GPP minus
respiration)
Source: From Odum [
40
]
or
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advantage given the modest computational power available in the 1950s and 1960s.
When the transfer of material between compartments is a fixed percentage of the
amount of material in a source compartment (called donor-controlled flow), linear
models have the property that, with a constant input of material into the system, the
equilibrium levels of materials are also the maximum amount. Importantly for
models of radioisotope transport, radioactive decay of the isotope is a linear,
donor-controlled process. Models of this formulation continue today in applications
to determine the transfer of radioactive material to human populations from reactors
or nuclear accidents such as the Chernobyl event.
In 1969, E.P. Odum wrote “The Strategy of Ecosystem Development,” [
43
]
a synthetic paper strongly based on ecological energetics and compartment models
in ecosystems. The emphasis of the paper was strongly in the area that nowadays
might be termed as sustainability science as is evidences by its first lines, “The
principles of ecological succession bear importantly on the relationship between
man and nature. The framework of successional theory needs to be examined as
a basis for resolving man's current environmental crisis.” Odum's view of succes-
sion was summarized as a tabular model of ecological succession (
Table 3.1
).
