What is ecology?

The term ecology was coined by Earnst Haeckel in 1869. The term ecology is derived from the Greek words oikos-home and logos-study. This makes ecology as the study of organisms in their natural homes interacting with their surroundings. These surroundings consist of both living and nonliving factors. The living factors of organisms are called biotic components and the nonliving factors are called abiotic components. In 1969, Odom defined ecology as the study of the structure and function of nature.

Ecology is not synonymous with environment but is closely related to the disciplines of physiology, evolution, genetics and behaviour. Ecology is a sub-discipline of biology and includes the study of

  • Life processes explaining adaptations.
  • Distribution and abundance of organisms.
  • Movement of materials and energy through living communities.
  • The successional development of ecosystems and
  • The abundance and distribution of biodiversity in context of the environment.

There are many practical applications of ecology such as

  •  Conservation biology.
  •  Wetland management.
  • Natural resources management (agriculture, forestry, fisheries).
  • City planning (urban ecology).
  • Community health, economics, basic and applied science.
  • Human social interactions (human ecology).

                                What is restoration ecology?

Restoration ecology emerged as a separate field in ecology in the 1980s. It is a scientific study supporting the practice of ecological restoration, which is the practice of renewing and restoring degraded, damaged or destroyed ecosystems and habitats in the environment by active human intervention and action. The practice of ecological restoration includes a wide scope of projects such as erosion control, reforestation, useage of genetically local native species, removal of non-native species and weeds, re -vegetation of the disturbed areas, day lighting streams, reintroduction of native species as well as habitat and range improvement for targeted species In 1992, O Wilson predicted that the 21st century will be the era of restoration ecology.

                                                      Organisation of life.

Life can be organised into several different levels of functional complexity. These functional levels are:








Individual – An individual is any living thing or organism. Individuals do not breed with individuals from other groups. Animals, unlike plants tend to be very definite with this term because some plants can crossbreed with fertile plants

Species – A group of interbreeding organisms that do not ordinarily breed with members of other groups is called specie. 

Populations – A population comprises of all the individuals of a given species in a specific area or region at a certain time. Its significance is more than that of a number of individuals because not all individuals are identical. Populations contain genetic variation within themselves and between other populations. Even fundamental genetic characteristics such as hair colour or size may differ slightly from individual to individual. More importantly, not all members of the population are equal in their ability to survive and reproduce.

Communities – Community refers to all the populations in a specific area or region at a certain time. Its structure involves many types of interactions among species. Some of these involve the acquisition and use of food, space or the other environmental resources. Others involve nutrient cycling through all members of the community and mutual regulation of population sizes. A community that has high diversity is more complex and stable than a community that has low density. This theory is founded on the observation that the food webs of communities of high diversity are more interconnected. Greater interconnectivity causes these systems to be more resilient to disturbance. If a  specie is removed, those species that relied on it for food have the option to switch to many other species that occupy a similar role in the ecosystem. In a low diversity ecosystem, possible substitutes for food may be non-existent or limited in abundance.

Ecosystems – Ecosystems are dynamic entities composed of the biological community and the abiotic environment. An ecosystem is abiotic and biotic in composition and structure is determined by the state of a number of interrelated environmental factors. Changes in any of these factors for example: nutrient availability, temperature, light intensity, grazing intensity and species density will result in dynamic changes to the nature of the systems. For example, a fire in the temperate deciduous forest completely changes the structure of the system. There are no longer any large trees, most of the mosses, herbs and shrubs that occupy the forest floor are gone and the nutrients that were stored in the biomass are quickly released into the soil, atmosphere and hydrology system. After a short time of recovery, the community that was once large mature trees now becomes a community of grasses herbaceous species and tree seedlings.

Biome – A biome in simple terms is a set of ecosystems sharing similar characteristics with their abiotic factors adapted to their environments.

Biosphere – When we consider all the different biomes, each blending into the other, with all human beings living in many different geographic areas, they form a huge community of humans, animals and plants in their defined habitats. A biosphere is the sum of all the ecosystems established on the Earth.

                                                         What is an ecosystem?

All the plants and animals and human beings along with the physical factors of the environment interact with each other and form an ecosystem. The term ecosystem was coined by A.G Tensley in 1935.

Definition:-Ecosystem is a self-regulating group of biotic communities of species interacting with one another and with their nonliving environment exchanging energy and matter. Ecology is often defined as the study of ecosystems. Ecosystem is the basic unit of study of ecology.

Ecosystems can be of two basic types:

i) Open Ecosystem: When there is a free exchange of energy and matter from outside. Most ecosystems are open i.e., open to outside influences and surrounding ecosystems for example a desert surrounded by farmland for instance, the two different ecosystems will affect one another.

ii) Closed Ecosystem: – When the ecosystem is isolated from outside. No materials can leave or enter but through which energy from external sources can flow. Earth is the example of a closed ecosystem.

Characteristics of an ecosystem: – Ecosystems show variations in their size, structure, composition etc. however all the ecosystems are characterised by certain basic structural and functional features which are common to all.

 Just as we call the cell to be structural and functional unit of life, an ecosystem is the fundamental structural and functional unit of an environment. Many ecosystems can exist in a specific environment. All ecosystems consist of biotic factors and a biotic factor. Biotic factors are all the living organisms in the environment. . Rainfall, temperature, wind, soil and minerals are all abiotic factors.  Examples of ecosystem can be forest, garden, pond, lake or an ocean ecosystem or man- made ecosystems.

A basic classification of the ecosystem is as follows:

1. Terrestrial-Any ecosystem existing above the surface of the earth e.g. Mountains, lowlands, deserts, forests. Grasslands etc.

2. Aquatic:-Any ecosystem existing under water e.g. – Ponds, rivers (fresh water) marine-oceans.

Excerpts from the book ENVIRONMENT 2020- by Archana Sharma.(Coypright)

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