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Ecology (生態学)

Mount Usu / Sarobetsu post-mined peatland
From left: Crater basin in 1986 and 2006. Cottongrass / Daylily

A model should be as simple as possible. But no simpler. (A. Einstein)
The derivation of word 'ecology'
Ecology (Oecology, Oekologie) = Eco + logy = Oikos (=household or at home) + Logos (logics)
Cf. economy: Ecology surveys energy flow and economics surveys money flow; viz. "Economics" deals with functional housekeeping, and "Ecology" deals with environmental housekeeping.


The totality or pattern of relations between organisms and their environment
If there are 100 ecologists, there are 100 kinds of definitions.
  1. The study of life on organisms (= environmental biology)
  2. General physiology about all organisms (narrow sense)
  3. The science of population (Clements)
  4. The scientific natural history - science of living things' economy and society (Elton 1927)
  5. The science dealing with the structure of nature or ecosystem, and Its relation to other sciences and its relevance to human civilization (Odum 1971)
  6. Study of the inter-relationships between organisms and their environments (Pianka 1978)

Classification (分類)

Scale or level

Synecology: Community ecology, ecosystem ecology, production ecology, etc.
Autoecology: Population ecology, genecology, sociobiology, etc.


Animal ecology, plant ecology, fungal ecology, bacterial ecology, etc.

Study area

Ocean ecology, terrestrial ecology, alpine ecology, wetland ecology, etc.
[Lectures: environmental conservation, environmental sicences, HUSTEP]

Hierarchy (階層)

The focus of ecology is on the levels of organizaiton from organisms to ecosystems (or nature).
Table. Levels of organization spectrum. Ecology focuses on the top-and portion of the spectrum; viz. the levels of organization from organisms to ecosystems (modified from Odum 1971 & Krebs 2000). Any more level aids in the study of another level, but never completely explains the phenomena occurring at that level.
    ⇓ nature                 ⇔ ⇅                           ⇑
    ⇓ landscapes             ⇔ ⇅                           ⇑
    ⇓ ecosystems (biosystem) ⇔ ⇅     ecosystem (biosystem) ⇑
    ⇓ communities (biome)    ⇔ ⇅                           ⇑
    ⇓ species                   ⇅                           ⇑
    ⇓ populations            ⇔ ⇅ energy  population system ⇑
    ⇓ organisms (individual) ⇔ ⇅         organismic system ⇑	
    ⇓ organs                 ⇔ ⇅         organ system      ⇑
    ⇓ cells                  ⇔ ⇅         cell system       ⇑
    ⇓ subcellular organelles ⇔ ⇅                           ⇑
    ⇓ genes                  ⇔ ⇅ matter  genetic system    ⇑
    ⇓ molecules              ⇔ ⇅                           ⇑

Animal ecology (動物生態学)

Territory (縄張り)

Any defended area (Noble 1939)

Catch per unit effort (捕獲量/単位努力量, CPUE)

indirect measure of the abundance of a target species
estimating absolute abundance of closed populations in the presence of successive removals

Urban ecology (都市生態学)

Structure and dynamics of urban environments

urban ecosystem - bioecological approach
urbanization(some impact) - bad case: self-domestication
→ indicator of urbanization → consider the merit and demerit of urban