CONTENT

Meaning of Ecology

Components of Ecology

Biomes and Local Biomes in Nigeria

Ecology is the study of living organisms to their environment. The study examines the relationships between living organisms and their environment. Ecology measures the factors that affect the environment; it studies the distribution of living organisms and how they depend on one another and their non-living environment for their survival.

Ecology is divided into two

(i) Autecology, which is the study of a single individual organism or a single species of organism and their environment. E.g., the study of Tilapia fish in a particular stream.

(ii) Synecology, which is the study of inter–relationships between groups of organisms or species of organisms living together in an area. E.g., the study of all organisms in a particular stream about their environment.

Ecological Concepts

1. Environment: This refers to all the factors in an organism’s surroundings, living or non-living. The factors include the place where the organism lives and the physical conditions in the place, the food, water, and air it takes in, the animals that prey on it, and the diseases that affect it.
2. Habitat: This is the place where an organism lives. It is the place that is suitable for the organism’s way of life e.g. the habitat of fish is water.

Examples of Habitat

Examples of habitats include:

(i) Aquatic habitats e.g. puddles, streams, ponds, seas, oceans.

(ii) Terrestrial habitats e.g. savanna, rain, forest, desert, etc.

(iii) Arboreal habitat i.e. tree tops and tree trunks.

3. Ecological Niche: This is the functional role and the space/specific portion of habitat occupied by a particular organism or species. E.g., a caterpillar and an aphid may live on the same plant but occupy different positions. The caterpillar lives on the leaves and feeds on them, while the aphid lives on the young shoot stem and sucks sap from it. The functional role includes the organism’s behavior, its feeding habits, and breeding habits i.e. the activities carried out while occupying the spaces in the habitat.
4. Population: This is the total number of all organisms of the same species or kind, living together in a given area/habitat. E.g. the total number of tilapia fish in a pond constitutes the population of Tilapia fish in that habitat.
5. Community: This is made up of all the populations of living organisms that exist together in a habitat. It is any naturally occurring group of different organisms living together and interacting in the same habitat. E.g. the community on a rotting log will include insects like termites, ants, lizards, small birds, and decomposers such as bacteria and fungi.
6. Biosphere: This refers to all parts of the atmosphere, hydrosphere, and lithosphere where life can be found. It is the largest and highest level of biological organization and is made up of various ecosystems.
7. Ecosystem: This is a self-supporting unit that is made up of a living part and a non-living part. It is a community of plants and animals interacting with themselves and with the non-living factors in their environment.

EVALUATION

1. Define ecology
2. Mention four ecological concepts and explain them

Components of an Ecosystem

The living part of the ecosystem is called its biotic component, while the non-living parts are called the abiotic component.

(a) Biotic component: This includes all living things/organisms in an environment. It is also called the biotic community. It is made up of;

(i) Food producer’s e.g. autotrophs (green plants), chemosynthetic bacteria and protophyta.

(ii) Food consumer’s i.e. heterotrophs such as animals, protozoa and some bacteria.

(iii) Decomposer’s i.e. saprophytes like fungi and some bacteria.

(b) Abiotic component: This consists of abiotic resources and abiotic conditions

Abiotic resources: These are what organisms need to stay alive. E.g., sunlight (a source of energy) and inorganic nutrients like water, nitrogen, carbon dioxide, phosphorus, etc.

Abiotic conditions: These are those factors that determine the kind of organisms that are found in a particular ecosystem. These factors affect the behavior, growth, and breeding patterns of organisms; they include;

(i) Climatic factors such as temperature, wind, light intensity, humidity, water currents, turbidity, rainfall, e.t.c.

(ii) Edaphic factors such as soils, rocks, topography, etc.

Other factors include air, water, storms, etc.

Characteristics of an Ecosystem

The following are the characteristics of an ecosystem:

(i) There is a flow of energy

(ii) There is recycling of inorganic nutrients.

The major interaction between the biotic and abiotic components involves feeding. Food producers like plants, trap sun-light energy and nutrients (e.g. carbon dioxide, nitrogen) etc. from the abiotic environment to make food. The energy and nutrients in the food is passed on to heterotrophs (consumers) such as animals which feed on plants or on one another. The animals and plants  eventually die, and decomposers feed on them, thereby obtaining their own energy. However, in the process, the decomposers release the nutrients from the animals and plants back into the abiotic environment (i.e., the soil). These  nutrients can be re-used again by the food producer’s. Plants also give out oxygen during photosynthesis and this is used by animals for respiration. Animals give off carbon dioxide during respiration, which plants take up.

NB: As the energy in food is passed from one organism to another, it eventually escapes into the environment and cannot be reused.

EVALUATION

1. Define (a) biotic factor (b) abiotic factor
2. Give two examples each of the concepts defined above
3. What characteristics make an ecosystem a self-supporting unit?

Biomes and local Biomes in Nigeria

Biomes

Biomes are large natural terrestrial (land) ecosystems. It is the largest community of organisms interacting with the non-living environment. Biomes are identified by their vegetation. Examples include forest, desert, savannas, etc. The type of vegetation is largely determined by climatic factors especially rainfall and temperature, as such, regions in the world which have similar climates also have similar biomes.

Local Biomes in Nigeria

This can be grouped into two major zones

1. The forest zone
2. Savanna zone
3. The forest zone: This is made up of vegetations having mainly trees, they include:

(a) Mangrove swamp:

A forest of tall woody trees with aerial roots. The rainfall is high and the soil is water logged throughout the year. Plants here include the white and red mangroves, raffia palms and coconut.

Mangrove swamps are found in states like the Delta, Cross River, Bayelsa etc. The climate is hot and wet throughout the year. Rainfall is heavy usually above 2500mm and the average monthly temperature is around 26ºc for most months of the year.

(b) Tropical Rainforest:

Consists of tall trees with buttress roots, with evergreen and broad leaves. The trees exist in canopies i.e. different layers, and prevent sunlight from reaching the forest floor, thus the vegetation on the forest floor is sparse. Epiphytes and climbers are common features in the trees.

The climate is hot and wet throughout the year. The mean annual temperature is 27ºc while the mean total annual rainfall is 2000mm. These forests are found in states like Oyo, Edo, Cross River, Ogun, Ondo, Imo and Rivers State.

c. Savanna zone:

This is made up mainly of grasses and includes;

(a) Southern Guinea Savanna: Consists mainly of tall grasses, with a few tall trees with broad leaves. The trees are scattered and deciduous. Examples include the locust beans trees, shear-butter and isobelina.

It has a moderate rainfall of between 100-150cm per annum. They are located in Enugu, Kogi, Benue, Kwara, Osun, Oyo, Ebonyi, and Ekiti States.

(b) Northern Guinea Savanna (Sudan Savanna): This has short but numerous grasses. The trees are scattered, short and deciduous. The trees have thorns while others have thick barks. The trees include acacia, date palm, baobab and silk cotton plants. The rainfall is low, about 50-100cm per annum. They may be found in states like plateau, Kaduna, Bauchi, Niger, Taraba, Adamawa and Kano.

(c) Sahel Savanna: It has very short and scanty grasses. There are short and tough shrubs or trees. The plants are mainly drought resistant and scattered examples include acacia, gum arabic and date palm. The temperature is very high and rainfall is very low, below 50cm per annum. It may be found in States like Bornu, Katsina, Sokoto, Yobe, Kebbi, Zamfara, Kano and Jigawa.

EVALUATION

1. What is a biome and how can it be identified?
2. Mention the two major biomes in Nigeria and the types.

ASSIGNMENT

Make a drawing of the map of Nigeria and outline the local biomes.