ECOLOGY

Introduction to Ecology

• Ecology is the study of organisms and their environment.
• All organisms show interdependence on one another.
• Organisms are affected by their environment, and they in turn affect the environment.
• Green plants manufacture food by photosynthesis which other organisms obtain directly or indirectly.
• Growth of plants is mainly affected by environmental factors such as soil and climatic factors.
• On the other hand, organisms modify the environment through various activities.
• This interrelationship comprises the study of ecology.
• The study of ecology is important in several fields of study such as agriculture and environmental studies.

Concepts and Terms Used in Ecology

Habitat:

This is the place or “home” that an organism lives or is found, e.g., forest or grassland.

Niche:

• A niche is the functional unit in the habitat.
• It includes not only the specific place in which an organism lives but also how the organism functions.
• To avoid or reduce competition, organisms are separated or segregated by their niches,
• for example, different species of birds make their nest on one tree, some at tips of terminal branches, and others feed on leaves, some on flowers and yet others on fruits of the same tree, i.e., food niche.
• Yet others feed on same food, e.g., worms in the same place but at different times – time niche.

Population:

• The term population refers to the total number of individuals of a species living in a given area at a particular time.
• Density is the number of individuals of a population found in a unit area, i.e.

Dispersion:

• This is the distribution of individuals in the available space.
• Dispersion may be uniform as in maize plants in a plantation;
• Random as in cactus plants in the savannah ecosystem or clumped together as in human population in cities.

Community:

• This is the term used to describe all the organisms living together in an area.
• During the development of an ecosystem, the species composition of a community changes progressively through stages.
• Finally a steady state is reached and this is described as the climax community.
• This development of an ecosystem is termed succession.
• Each stage in development of an ecosystem is a sere.
• Succession is primary when it starts with bare ground, and secondary when it starts in a previously inhabited area e.g. after clearing a forest.

See also

BIOLOGY PRACTICAL ACTIVITIES

FEATURES USED FOR IDENTIFICATION IN PLANTS

CHARACTERISTICS OF VERTEBRATES

KINGDOM PLANTAE

KINGDOM PROTOCTISTA