1 ecological modeling
1.1 new integrative approach in ecology
1.2 ecosystem simulation
1.3 ecological analog of ohm s law
1.4 silver springs study
ecological modeling
a new integrative approach in ecology
in 1950 ph.d. thesis, h.t.odum gave novel definition of ecology study of large entities (ecosystems) @ natural level of integration . hence, in traditional role of ecologist, 1 of odum s doctoral aims recognize , classify large cyclic entities (ecosystems). of aims make predictive generalizations ecosystems, such whole world example. odum, large entity, world constituted revolving cycle high stability. presence of stability which, odum believed, enabled him talk teleology of such systems. moreover, @ time of writing thesis, odum felt principle of natural selection more empirical, because had teleological, stability on time component. , ecologist interested in behavior , function of large entities on time, odum therefore sought give more general statement of natural selection equally applicable large entities small entities traditionally studied in biology.
hence odum had aim of extending scope , generality of natural selection, include large entities such world. extension relied on definition of entity combination of properties have stability time. odum s approach motivated lotka s idea s on energetics of evolution.
ecosystem simulation
in writing history of ecosystem concept, golley noted odum tended think in form of analogies, , gave example, if world heat engine, then... in vein, odum can understood extending dynamical analogies establish analogies between electrical, mechanical, acoustical, magnetic , electronic systems, include ecological systems.
odum used analog of electrical energy networks model energy flow pathways of ecosystems. odum s analog electrical models had significant role in development of approach systems , have been recognized 1 of earliest instances of systems ecology.
electron flow in electrical network represented flow of material (e.g. carbon) in ecosystem, charge in capacitor analogous storage of material, , model scaled ecosystem of interest adjusting size of electrical component.
ecological analog of ohm s law
passive electrical equivalent of energy systems language storage icon
in 1950s odum introduced electrical circuit diagrams of ecosystems ecological society of america. claimed energy driven through ecological systems ecoforce analogous role of voltage in electrical circuits.
odum developed analogue of ohm s law aimed representation of energy flows through ecosystems. in terms of steady state thermodynamics, ohm s law can considered special case of more general flux law, flux (
j
{\displaystyle j}
) proportional driving thermodynamic force (
x
{\displaystyle x}
) conductivity (
c
{\displaystyle c}
). is:
j
=
c
x
{\displaystyle j=cx}
.
kangas states odum concluded thermodynamic systems, ecosystems should obey force-flux law. hence ohm s law , passive electrical analog circuits can used simulate ecosystems (ibid.). in simulation, odum attempted derive ecological analog electrical voltage. voltage, or driving force, related have measured years, biomass, in pounds per acre. analogous concept required biomass activity, is, thermodynamic thrust, may linear. in nature still uncertain, new concept.
such consideration led odum ask 2 important methodological questions: 1) electrical significance of function observed in nature? 2) given electrical unit in circuit, in ecological system? example, diode in nature? 1 needs diode allow biomass accumulate after voltage of sun has gone down. otherwise circuit reverses. higher organisms fish diodes.
the silver springs study
energy diagram: energy , matter flows through ecosystem, adapted silver springs model. h herbivores, c carnivores, tc top carnivores, , d decomposers. squares represent biotic pools , ovals fluxes or energy or nutrients system.
silver springs common type of spring-fed stream in florida, constant temperature , chemical composition. study howard odum conducted here first complete analysis of natural ecosystem.
odum started overall model , in work used diagramming methodology similar sankey diagrams used in chemical process engineering. in model energy , matter flows through ecosystem: h herbivores, c carnivores, tc top carnivores, , d decomposers. squares represent biotic pools , ovals fluxes or energy or nutrients system.
started overall model odum mapped in detail flow routes , stream. measured energy input of sun , rain, , of organic matter - of bread tourists threw ducks , fish - , measured energy gradually left spring. in way able establish stream s energy budget .
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