Successive levels of organization in the coils-to –ecosystem spectrum are shwn along the top of the figure and levels of major ecological concern indicated to the right. Different procedures and  different tools are need at the various levels of biological organization, but the discovery of the relation between structure and function is a goal common to all biological research. Left laboratory investigator using an electron miscroscope to study cell structure (USDA photo)  .center; fisher ecology students studying size and composition of a pope lation of trout. (US Department of interior fish and wildlife service, ) right oceanographic  lowering special servable device in the study of the sea, a natural self-sustained, solar –powered ecosystem. (wood Hole oceanographic institution).

Above ; the city, a high – energy fuel – power erred  ecosystem that require as a cause  Of solar – powered ecosystems for its life support maintenance.( Dept of housing and urban development)

Totality of pattern of ecology relations between organisms and environment

      It is interesting that the word ecology comes from the same root as the word economices, which deals with housekeeping in the sense of management of man’s works. The scope of ecology has expanded considerably as man has become increasingly aware of these imbalances, an attitude change currently known as the environmental awareness movement. Until very recently, ecology was considered in academic circles to be a branch of biology, which along with molecular biology, genetics, developmental biology, and evolution was often, but by no means always, included in a core curriculum for biology. In this context ecology was considered to be the same things as environmental biology, as indeed was inferred in the first edition of this book. Now however, the emphasis has shifted to the study of environmental systems, the whole household as it were a scope that is well within the root meaning of the word, as we have seen. Thus, ecology has grown from a division of biological science to a major interdisciplinary science that links together the biological, physical, and social sciences.
ecology sense by environment

    Perhaps the best way to delimit the field of ecology, in terms of shifting emphasis, is to consider the concept of levels of organization. we may conveniently visualize a sort of levels spectrum in which biological units interacting with the physical environment (energy and matter) successively combine to produce a series of living systems (bios stems). The word ‘’system’’ is used here in the primary dictionary sense as a regularly interacting or interdependent group of items forming a unified whole. Ecology is concerned largely with the right hand - portion of the spectrum, that is the levels beyond that of the individual organisms.

In ecology the term population, originally coined to denote a group of people, is broadened to include groups of individuals of any kind of organism. Likewise, community in the ecological sense (sometimes designated as biotic community) includes all of the populations of a given area. The community and the nonliving environment function together as an ecological system or ecosystem. A parallel term often used in the German and Russian literature is biogeocoenosis, which translated means ‘’life and earth’s functioning together’’. Finally, biosphere is a widely used term for all of the earth’s ecosystems functioning together on the global scale. Or from another viewpoint, we can think of the biosphere as being that portion of the earth in which ecosystem can operate – that is, the biologically, inhabited soil, air , and water. The biosphere merges imperceptibly (that is, without sharp boundaries) into the lithosphere, and the atmosphere, the other major subdivisions of our earth spaceship.

Finally, it should be emphasized that as with any spectrum, the levels – of – organization. Hierarchy is a continuous one; divisions are arbitrary and set for convenience and ease of communication.  It is often convenient to delimit levels between those in figure 1 – 1 .for example, a  ‘’host – parasite system’’ which involves the interaction of two different populations would represent a level between  ‘’population’’ and ‘’community’’.

The shift in emphasis alluded to previously has resulted from an increased interest in, and study of, the ecosystem and global levels. This does not mean that there is, or should be, any less study of organisms and populations as such. It is just that the focus in ecology has moved to the right of the figure 1-1 spectrum. The basic reason for such a shift in emphasis stems from the realization that decisions must ultimately be made at the level of the ecosystem and biosphere if man is to avoid a major environmental crisis.