An ecosystem includes all of the living things (plants, animals and organisms) in a given area, interacting with each other, and also with their non-living environments (weather, earth, sun, soil, climate, atmosphere).
In an ecosystem, each organism has its’ own niche, or role to play.
Consider a small puddle at the back of your home. In it, you may find all sorts of living things, from micro-organisms, to insects and plants. These may depend on non-living things like water, sunlight, turbulence in the puddle, temperature, atmospheric pressure and even nutrients in the water for life.
This very complex, wonderful interaction of living things and their environment, has been the foundations of energy flow and recycle of carbon and nitrogen.
Anytime a ‘stranger’ (living thing(s) or external factor such as rise in temperature) is introduced to an ecosystem, it can be disastrous to that ecosystem. This is because the new organism (or factor) can distort the natural balance of the interaction and potentially harm or destroy the ecosystem.
Usually, biotic members of an ecosystem, together with their abiotics factors depend on each other. This means the absence of one member, or one abiotic factor can affect all parties of the ecosystem.
Unfortunately ecosystems have been disrupted, and even destroyed by natural disasters such as fires, floods, storms and volcanic eruptions. Human activities have also contributed to the disturbance of many ecosystems and biomes.
Scales of ecosystems
Ecosystems come in indefinite 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.
To make things simple, let us classify ecosystems into three main scales.
A small scale ecosystem such as a pond, puddle, tree trunk, under a rock etc.
A medium scale ecosystem such as a forest or a large lake.
A very large ecosystem or collection of ecosystems with similar biotic and abiotic factors such as an entire Rain forest with millions of animals and trees, with many different water bodies running through them.
Ecosystem boundaries are not marked (separated) by rigid lines.
They are often separated by geographical barriers such as deserts, mountains, oceans, lakes and rivers. As these borders are never rigid, ecosystems tend to blend into each other. This is why a lake can have many small ecosystems with their own unique characteristics. Scientists call this blending “ecotone”
Ecosystems can be put into 2 groups. If the ecosystem exists in a water body, like an ocean, freshwater or puddle, it is called an aquatic ecosystem. Those that exists outside of water bodies are called terrestrial ecosystems.
Levels of organisation in an ecosystem
Individual, Species, Organism:
An individual is any living thing or organism. Individuals do not breed with individuals from other groups. Animals, unlike plants, tend to be very definite with this term because some plants can cross-breed with other fertile plants.
In the diagram above, you will notice that Gill, the goldfish, is interacting with its environment, and will only cross-breed with other gold fishes just like her.
A group of individuals of a given species that live in a specific geographic area at a given time. (example is Gill and his family and friends and other fishes of Gill’s species) Note that populations include individuals of the same species, but may have different genetic makeup such as hair/eye/skin colour and size between themselves and other populations.
This includes all the populations in a specific area at a given time. A community includes populations of organisms of different species. In the diagram above, note how populations of gold fishes, salmons, crabs and herrings coexist in a defined location. A great community usually includes biodiversity.
As explained in the pages earlier, ecosystems include more than a community of living organisms (biotic) interacting with the environment (abiotic). At this level note how they depend on other abiotic factors such as rocks, water, air and temperature.
A biome, in simple terms, is a set of ecosystems in a geographic area.
When we consider all the different biomes, each blending into the other, will all humans living in many different geographic areas, we form a huge community of humans, animals and plants, in their defined habitats. A biosphere is the sum of all the ecosystems established on Earth.
Important ecosystem terminology
Adaptation: An adaptation is a way an animal’s body helps it survive, or live, in its environment. A good example is the polar bear. Its while fur helps it to camouflage, so its prey cannot see it. Its Thick fur also provides the warmth to help it survive in its frozen environment
Abiotic: Physical, or non-living, factor that shapes an ecosystem. Examples include rocks, climate, pressure and humidity.
Biotic: Living factors such as plants, animals, fungi, protist and bacteria are all biotic or living factors
Habitat: the area where an organism lives, including the biotic and abiotic factors that affect it
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
Food Web: The complex feeding network occurring within and between food chains in an ecosystem, whereby members of one food chain may belong to one or more other food chains.
Habitat: The place where a particular population (e.g., human, animal, plant, micro-organism) lives and its surroundings. Example, The anaconda snake lives in water and thrives very well there.
Plankton: Microscopic plants and animals that live in water. — www.ecoworld.com.