SSS1 Biology - Basic Ecological Concepts | Ecology and Ecosystem

BEHAVIOURAL OBJECTIVES:

By the end of the lesson, students should be able to:

i. Define ecology.
ii. State and explain two(2) main branches of ecology.
iii. Define ecological concepts.
iv. State and explain two(2) main components of an ecosystem.
v. State seven(7) interactions among the components of an ecosystem.

INTRODUCTION: The word “Ecology” is derived from a Greek word “Oikos” which means home or dwelling place. Ecology simply means study of plants and animals in relation to their environment.

Definition of Ecology

Ecology is defined as the study of inter-relationship between living organisms and their external environment.

Branches of Ecology

i. Autecology – Concerned with the study of single species of organisms and its environment.
ii. Synecology – Concerned with the study of many species of organisms and their environment.

Ecological Concepts

i. Environment – The sum total of the biotic and abiotic factors that actually affects individual organisms.
ii. Biosphere – Part of the Earth occupied by living organisms.
iii. Atmosphere – Part of the Earth occupied by gases. E.g. O2, CO2, N2, etc.
iv. Hydrosphere – This is part of the Earth surrounded by water. E.g. Ocean, River, Streams, etc.
v. Lithosphere – This is the solid portion of the Earth. E.g. Rocks/Hills/Mountains.
vi. Habitat – This is the natural dwelling place/home of an organism.
vii. Ecological niche – defined as the functional position of an organism in a community and the role played by the organism.
viii. Biome – refers to the largest community of organisms maintained by the climate. E.g. Rainforest biome.
ix. Population – defined as the total number of organisms of the same species living together in an area.
x. Community – consist of population of different species of organisms living together in an area.

Components of an Ecosystem

Two(2) main components of an ecosystem are:

1. Biotic(living) components – Include living things(plants and animals). They are grouped into producers, consumers and decomposers.
   i. Producers – They are autotrophs(green plants) which can manufacture their own food through the process known as Photosynthesis.
   ii. Consumers – They are heterotrophs(animals) which cannot manufacture their food but depend directly or indirectly on plants for their food. They include; Primary, Secondary and Tertiary consumers.
   iii. Decomposers – These organisms are responsible for breaking down dead organic materials of plants and animals.
   Two(2) classes of decomposers are;
   a. Micro-decomposers – These are small microscopic organisms that can cause delay. E.g. Bacteria and Fungi.
   b. Macro-decomposers – These are bigger or macroscopic organisms that can cause the decay of dead organic materials. E.g. Earthworm, Termites, Snails, etc.
2. Abiotic components – This include non-living things e.g. rainfall, soil, rock, water, temperature, humidity, wind, sunlight, CO₂, O₂, etc.

Interactions among the components of ecosystem

i. Plants release oxygen for animals to respire.
ii. Animals release Carbondioxide for plants to respire.
iii. Green plants interacts with sunlight for photosynthesis.
iv. Plants absorb water/mineral salts for their growth.
v. Carbondioxide and water are used by green plants for photosynthesis or carbohydrate production.
vi. Animals feed on green plants for their energy.
vii. Micro-organisms breakdown dead plants and animals to release nutrients to the soil which in turn is absorbed by plants.