Nature, Ecology, and the Environment – Concepts and Definitions

“There is no “original” state in nature, no nature-in-itself in the sense that a fixed set of characteristics holds true, like the law of gravity, always and everywhere. Nature resembles less a law than a story. And the story is not over. Thus to inquire of nature is to inquire of time, of circumstance and of contingency. What was natural three billion years ago – an empire of anaerobic bacteria – would strike most of us as decidedly unnatural today.” (Edwin Dobb, 1992 1)


  • The word originates from the Greek root oikos, “at home”, and *ology, “the study of something.”
  • Haeckle, (1870), defined it in this way: “By ecology we mean the body of knowledge concerning the economy of Nature – the investigation of the total relations of the animal to its inorganic and organic environment.
  • Burdon-Sanderson (1890s): Elevated Ecology to one of the three natural divisions of Biology: Physiology – Morphology – Ecology.
  • Elton (1927): “Scientific natural history”
  • Andrewartha (1961): “The scientific study of the distribution and abundance of organisms”
  • Odum (1963): “The structure and function of Nature”
  • Ecology is the scientific study of the processes regulating the distribution and abundance of organisms and the interactions among them, and the study of how these organisms in turn mediate the transport and transformation of energy and matter in the biosphere (i.e., the study of the design of ecosystem structure and function).
  • Carl Woese 2006: “However it is said, the future of biology lies not in the ongoing reduction of biology to molecular tidbits, but in studying biology in its essence; studying the organism and the environment as primary, not derived entities. Both, however, are facets of a single grand problem, the nature of biological organization. Such an emphasis brings to light an entirely different future for biology, one in which understanding the dynamic of the biosphere and the evolution and nature of cellular organization are central issues.”

Levels of Ecology

Biosphere: The earth’s ecosystem interacting with the physical environment as a whole to maintain a steady state system intermediate in the flow of energy between the high energy input of the sun and the thermal sink of space (merges with atmosphere, lithosphere, hydrosphere…).

Biome: Large scale areas of similar vegetation and climatic characteristics.

Ecosystem: Set of organisms and abiotic components connected by the exchange of matter and energy (forest, lake, coastal ocean). Or, “the smallest units that can sustain life in isolation from all but atmospheric surroundings.”

Community: Interacting populations which significantly affect each other’s distributions and abundance (intertidal, hot spring, wetland).

Population: Group of interacting and interbreeding organisms

Cell/Organism → Organelle → Molecule → Atom


Biodiversity is the variety of species and ecosystems on Earth and the ecological processes of which they are a part – including ecosystem, species, and genetic diversity components. The United Nations Convention on Biological Diversity provides the following definition for biodiversity: “The variability among living organisms from all sources including, inter alia [among other things], terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems.”
In short, the term is used to refer to life in all its forms and the natural processes that support and connect all life forms. Biodiversity is not easily defined because it is more than just the sum of its parts. All of its elements, regardless of whether we understand their roles or know their status, are integral to functioning, evolving, and resilient ecosystems. The levels of organization of biodiversity include ecosystems, species and genes.

ecosystem: is a dynamic complex of plant, animal and microorganism communities and non-living (abiotic) elements, all interacting as a functional unit. An ecosystem’s character changes as community members and physical contexts change, sometimes crossing a threshold of tolerance within the system that results in its inability to return to its previous form.
Species are a complete, self-generating, unique ensemble of genetic variation, capable of interbreeding and producing fertile offspring. They (and their subspecies and populations) are generally considered to be the only self-replicating units of genetic diversity that can function independently.
Genes are the working units of heredity; each gene is a segment of the DNA molecule that encodes a single enzyme or structural protein unit. Genetic diversity is the foundation of all biodiversity. Genetic variation permits populations to adapt to changing environments and continue to participate in life’s processes.


  1. “Cultivating Nature” The Sciences Jan/Feb 1992 p. 45