Ecosystems
Look at the picture below:
Ecosystems
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An ecosystem consist of all living and non-living things that depend on each other
to survive.
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Ecology is the study of the interaction of living and non-living things
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Biotic is the living part of an ecosystem. (plants, animals, organisms)
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Abiotic is the non-living part of an ecosystem (weather, sun, soil, earth,
atmosphere, climate)
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Organisms are all living things in an ecosystem.
Scales of ecosystems
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Ecosystems come in different sizes. It can exist in a small area such as
underneath a rock, a decaying tree-trunk, or a pond in your village, or it
can exist in large forms such as an entire rain forest. Technically, the Earth
can be called a huge ecosystem.
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To make things simple, let us classify ecosystems into three main scales.
Micro:
A small scale ecosystem such as a pond, puddle, tree trunk, under a rock
etc.
Messo:
A medium scale ecosystem such as a forest or a large lake.
Biome:
A very large ecosystem such as an entire Rain forest with millions of animals
and trees, with many different water bodies running through them.
Sea
Forest
City
Mangrove
Swamp
Rainforest
Pond
Ocean
Levels of Organization in the Ecosystem
To understand the levels of belonging in an ecosystem, let us consider the diagram below.
Levels of Organisms in the Ecosystem
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An individual is any living thing or organism. Individuals do not breed with individuals from other
groups.
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Within each ecosystem, there are habitats which may also vary in size. A habitat is the place where a
population lives.

A population is a group of living organisms of the same kind living in the same place at the same time.
All of the populations interact and form a community.

The community of living things interacts with the non-living world around it to form the ecosystem.

The habitat must supply the needs of organisms, such as food, water, temperature, oxygen, and
minerals.
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If the population's needs are not met, it will move to a better habitat.
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So the processes of competition, predation, cooperation, and symbiosis occur.
Roles of Different Population: Niches
A niche is the role the population plays within a community and ecosystem.
Two different populations can not occupy the same niche at the same time, however.
What is the role of an ant?
What is the role of an earthworm?
What is the role of humans?
What is the role of a lion?
What is the role of plants?
Niche of the Population
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Factors that determine the role of the population:
1. Eating habits
2. Predatoriness
3. Plants produce their own food so they are called producers
4. Animals are consumers. They cannot make their own food. ( carnivore,
omnivore, herbivore)
5. Scavengers: clean the environment
6. Decomposers: feed on dead plants and animals causing them to
decay.
Population in Trouble
Factors that limit a population of species

Migration of competitors: two species share a requirement for a limited resource  reduces
fitness of one or both species
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Human impact : activities done by humans: hunting

Pollution
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Pesticides and competitions
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Removal of predators
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Environmental change
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Food webs
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Predetation
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Industrialization
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Natural disasters
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Over population
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Symbiosis: Relationship in which two species live closely together, usually
benefiting from each other. There are three types of this relationship:
1. Parasitism: parasite benefits, host is hurt.

2. Commensalism: one species benefits, the other is neither hurt nor
helped.
3. Mutualism: both species benefit
BIOMES

Biomes are very large ecological areas on the earth’s surface, with fauna
and flora (animals and plants) adapting to their environment.

Biomes are often defined by abiotic factors such as climate, relief,
geology, soils and vegetation.

A biome is NOT an ecosystem, although in a way it can look like a massive
ecosystem.
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If you take a closer look, you will notice that plants or animals in any of the
biomes have special adaptations that make it possible for them to exist in
that area. You may find many units of ecosystems within one biome.
Five Major Categories of Biomes on Earth
The Desert Biomes: They are the Hot and Dry Deserts, Semi Arid Deserts, Coastal Deserts)
The Aquatic Biomes: Aquatic biomes are grouped into two, Freshwater Biomes (lakes and ponds, rivers and streams,
wetlands) and Marine Biomes (oceans, coral reefs)
The Forest Biomes: There are three main biomes that make up Forest Biomes. These are the Tropical Rainforest,
Temperate and Boreal Forests.
The Grassland Biomes: There are two main types of grassland biomes: the Savanna Grasslands and the Temperate
Grasslands.
The Tundra Biomes: There are two major tundra biomes—The Artic Tundra and The Alpine Tundra
Biomes play a crucial role in sustaining life on earth. For example, the Aquatic biome is home to millions
of fish species and the source of the water cycle. It also plays a very important role in climate formation.
The terrestrial biomes provide foods, enrich the air with oxygen and absorb carbon dioxide and other
bad gases from the air. They also help regulate climate and so on.