WEEK ONE

DATE………………………

TOPIC: BASIC ECOLOGICAL CONCEPTS

DEFINITION OF ECOLOGY

Ecology is the study of plant and animals (as well as microorganism) in

relation to their environment. .

BRANCHES OF ECOLOGY

Depending on whether the organisms are studied alone or in groups, ecology is divided into
two:

1. AUTECOLOGY: This is the study of an individual organism or a single

species of organism and its environment e.g. the study of a student
and his school environment.
2. SYNECOLOGY: This involves studying the inter-relationships between
groups of organisms or different species of organism living together
in an area e.g. study of fish, crabs, seaweeds, etc in a pond.

ECOLOGICAL TERMS

The various concepts closely associated with ecology include;

1. ENVIRONMENT

This includes external and internal factors, living or nonliving which affects an organism or a
group of organisms. These include the habitat (with its peculiar physical conditions e.g. light,
food, water, air), the animals preying on other animals or the diseases affecting the organism.

2. BIOSPHERE (ECOSPHERE)

This is the zone of the earth occupied by living organisms so as to carry out their biochemical
activities.

The ecosphere consists of 3 major portions:-

 Lithosphere:- this is the solid portion (the outer-most zone) of the

earth which is made up of rocks and minerals. This zone forms 30%
of the earth surface and it is the basis of human settlement.
 Hydrosphere:- this is the liquid (aquatic) part of the biosphere. It
covers about 70% of the earth’s crust. It consist of water in various
forms; solid, liquid or gas (water vapour), hydrosphere includes
lakes, pools, spring, oceans, ponds, rivers, etc.
 Atmosphere: – this is the gaseous portion of the earth. It consists of
three main gases; nitrogen (78%), oxygen (21%) and carbon (iv)
oxide (0.03%). There are also 0.77% rare gases.
 3. HABITAT

This is a place where an organism is naturally found. Habitat is always affected by

environmental factors. Habitat can be divided into three:-

 Aquatic habitat: this is where plants and animals (as well as micro
organisms) live in water e.g. Sea, ocean, lagoons, streams, etc.
 Terrestrial habitat: this is where the organisms live on land e.g.
forests, grassland, (savanna), desert etc.
 Arboreal habitat: These include tree trunks and tree tops where
some organisms (usually animals) are naturally found.

4. ECOLOGICAL NICHE

This refers to the habitat and the entire habit (behavioural, feeding, breeding) of an organism.
It is the physical space occupied by an organism and its functional role in the community.

5. POPULATION

This is the total number of organisms of the same species living together in a habitat e.g.
population of cockroaches in Biology laboratory.

6. COMMUNITY

This is made up of all the populations of living organisms that exists together in a habitat e.g.
a community of decomposer, insects and birds on a decaying log of wood.

7. ECOLOGICAL SYSTEM (ECOSYSTEM)

This refers to the basic functional unit in nature, which consists of all living factors and their
interaction with non-living factors of the environment. An ecosystem can be natural or
artificial.

8. BIOMES

This is a large natural terrestrial ecosystem. It is a plant and animal community produced and
maintained by the climate.

COMPONENTS OF AN ECOSYSTEM

There are two main components of the ecosystem, the abiotic and the biotic components.

ABIOTIC COMPONENTS

These are non-living components and they are basic elements and compounds of the
environment in which an organism lives.

Abiotic components include organic substances (e.g. carbohydrates, lipids, and proteins),
inorganic substances (e.g. CO2, H2O), climatic factors (e.g. light, temperature, rainfall) as well
as edaphic factors (e.g. soil types, texture, topography etc).
BIOTIC COMPONENTS

These are the living things in the ecosystem. These include the producers, the consumers and
the decomposers.

1. Producer: These are autotrophs in that they synthesize their food

from simple inorganic substances e. g. green plants, protophytes
and chemosynthetic bacteria.
2. Consumers: These are heterotrophs which feed on the producers or
one another. They may be primary, secondary or tertiary consumers
e.g. non-green plants, animals protozoa and some bacteria
3. Decomposers: These are saprophytes. They break down remains of
plants and animals and release usable nutrients to the soil. These
nutrients are used by plants to make food e.g. fungi and some
bacteria

WEEK TWO DATE

………………………

TOPIC: BIOMES

BIOMES

Biomes are large natural terrestrial ecosystem, identified by their dominant vegetation.

Climatic factors determine the type of vegetation in a biome. These factors may include
rainfall, relative humidity, temperature, wind and light.

LOCAL BIOMES

The local biomes particular to Nigeria include the following:

 mangrove swamp
 tropical rain forest
  savanna (northern and southern Guinea savanna, Sudan savanna
and sahel savanna)

1. MANGROVE SWAMPS

These are found in the tropics along coastal region and river mouths. Mangrove swamps are
forest of:

 Small, evergreen, broad-leaved trees growing in shallow, brackish water or wet soil.
 Many mangrove trees have pop roots and breathing roots called pneumatophores
 The climate is hot and wet.
 Have total annual rain fall of above 250cm and temperature of about 260c.
 Found in the delta region of Lagos, Delta, Rivers, Bayelsa and Cross rivers states.

2. TROPICAL RAIN FOREST:

This occurs in the region that is between the equator and latitude 50-100N and S. It has the
following characteristics:

 The forest are mainly lowland.

 The climate is hot and wet.
 It consists of broad leaved trees that are mostly ever green; the
leaves are gradually shed throughout the year and replaced by new
ones.
 The trees form canopy strata with their interior having low light
intensity, high humidity and damp floor.
 The trees possess thin bark.
 The forest is rich in epiphytes and wood climbers.
 The annual rainfall and temperature are 200cm and 27 0c
respectively.

In Nigeria, tropical rainfall is found in Edo, Delta, Ondo, Imo, Lagos, Rivers state e.t.c.

3. SAVANNA

These are tropical grassland in Africa. They are made up mainly of grasses. The savanna
region has a hot and wet seasons (290c) which alternate with a cool and dry season (180c).
The total annual rainfall around 50cm-150cm. During the dry season, the grasses are usually
dry and brown and bush fire is common occurrences.

South Guinea savanna (the largest of all the biomes in Nigeria) has tall grasses with scattered,
deciduous trees. It is found in Enugu, Kogi, Benue, Kwara, Oyo, Osun, Ekiti State etc.

Northern Guinea Savanna has short and numerous grasses with scattered, deciduous trees,
sometimes with thorns and thick barks. it is found in plateau, Kaduna, Bauchi, Niger, Kano,
Adamawa states etc.

Sudan savanna has the shorter grasses fewer trees which are more scattered. It is found in
Kano and parts of Borno, Sokoto, Niger, Bauchi states e.t.c
Sahel savanna has high temperature and low rainfall with short and scanty grasses as well as
short and tough shrubs or trees. The plants are drought-resistant. It is found in Borno,
Kastina, Sokoto, Yobe, Kano, Jigawa states etc.

WORLD BIOMES

Of all abiotic factors affecting ecological system, temperature and rainfall determine the
world biomes. The biomes include: tropical rain forest, temperate forest, coniferous forest,
temperate shrubland, savanna, temperate grassland, desert, and tundra and mountain
vegetation.

WEEK THREE DATE

……………………

TOPIC: POPULATION

POPULATION CHARACTERISTICS

These include population size, density, frequency, percentage cover and distribution.

1. Population size: – this is the number of organisms of the same

species living together in a given area at a particular time.

2. Population density: – this is the number of a particular species per unit area or volume
of the habitat. Therefore

Population density = population size / area of habitat.

3. Population frequency: – this is the number of times an organism

occurs within a given area or habitat.
4. Percentage cover: – this refers to how much space or area an
organism occupies its habitat.
5. Population growth rate: – this refers to the net result of the influence
of natality (birth rate) and mortality (death rate) of organism in a
given habitat.
6. Population distribution: – this refers to the ways in which individuals
of the same species are arranged in a given habitat, either
randomly, evenly or clumped.

POPULATION STUDIES
 1. Choose the habitat.
2. Select the sampling method to be used.
3. Collect, count and record the different types of organisms present.
Sampling using a quadrant or transcent using a tape can be
adopted.
4. Identify the dominant species i. e. the species that has greater
influence on the other members of the community.
5. Repeat the population studies at intervals.
6. Determine the population characteristics.

FACTORS AFFECTING POPULATION

 Natality; Ability of organisms to reproduce to increase its population

 Mortality; Death rate.
 Immigration; Movement of organisms from different habitats into a
new habitat and this increases the population of the new area,
decreasing the population of the former habitat.
 Emigration; Movement of organisms out of a habitat due to
unfavourable conditions e.g. food scarcity etc. This reduces the
population of the habitat.
 Availability of food; Animals tend to migrate to where there is plenty
of food, thereby increasing the population of such places.
 Seasonal climatic changes; whether the change is favourable or not
determines the stay or migration of organisms into or out of a
habitat.
 Breeding season some organisms move out of their habitats during
this season (e.g. fishes); hence the population drops.
 Natural disasters; Like fire, drought, floods, earthquakes etc lead to
a decrease in population through the death of organisms out of such
habitat

MEASUREMENT OF ECOLOGICAL FACTORS

These factors can be measured using some instruments as shown below.

INSTRUMENTS USES
a. Photometer Light intensity
b. Hydrometer Light intensity in water
c. Wind vane Direction of wind
d. Anemometer Speed of wind
e. Rainguage Amount of rainfall
f. Hygrometer Relative humidity
g. Barometer Pressure
h. Glass thermometer Temperature
i. Colorimeter or pH scale Acidity / Alkalinity
j. Secchi disc Turbidity
k. Sweep insect net Catching insects

EVALUATION

1. Define the following terms: (i) Percentage cover (ii) Population size
(iii) Population frequency (iv) Population density.
2. Mention two methods of determining population size.
3. How do you determine the population density of insect on a piece of
land?
4. How do you determine the population of grasses in a piece of land?