What is an Ecosystem?

An ecosystem, a term very often used in biology, is a community of plants and animals interacting with each other in a given area, and also with their non-living environments. The non-living environments include weather, earth, sun, soil, climate and atmosphere.

The ecosystem relates to the way that all these different organisms live in close proximity to each other and how they interact with each other. For instance, in an ecosystem where there are both rabbits and foxes, these two creatures are in a relationship where the fox eats the rabbit in order to survive. This relationship has a knock-on effect with the other creatures and plants that live in the same or similar areas. For instance, the more rabbits that foxes eat, the more the plants may start to thrive because there are fewer rabbits to eat them.

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According to Wikipedia,

“An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system. These biotic and abiotic components are regarded as linked together through nutrient cycles and energy flows.

As ecosystems are defined by the network of interactions among organisms, and between organisms and their environment, they can be of any size but usually encompass specific, limited spaces (although some scientists say that the entire planet is an ecosystem).”

Ecosystems can be huge, with many hundreds of different animals and plants all living in a delicate balance, or they could be relatively small. In particularly harsh places in the world, such as the North and South Poles, the ecosystems are relatively simple because there are only a few types of creatures that can withstand the freezing temperatures and harsh living conditions.

Some creatures can be found in multiple different ecosystems all over the world in different relationships with other or similar creatures. Ecosystems also consist of creatures that mutually benefit from each other.

For instance, a popular example is that of the clownfish and the anemone – the clownfish cleans the anemone and keeps it safe from parasites as the anemone stings bigger predators that would otherwise eat clownfish.

Earth as an ecosystem stands out in the all of the universe. There’s no place that we know about that can support life as we know it, not even our sister planet, Mars, where we might set up housekeeping someday, but at great effort and trouble we have to recreate the things we take for granted here.

~ Sylvia Earle

An ecosystem can be destroyed by a stranger. The stranger could be a rise in temperature or rise in sea level or climate change. The stranger can affect the natural balance and can harm or destroy the ecosystem. Its a bit unfortunate but ecosystems have been destroyed and vanished by man-made activities like deforestation, urbanization and natural activities like floods, storms, fires or volcanic eruptions.

Ecosystem Structure

Each ecosystem has two main components:

1. Abiotic Components

The non-living factors or the physical environment prevailing in an ecosystem form the abiotic components. These are Climatic Factors that include rain, temperature, light, wind, humidity etc. and Edaphic Factors including soil, pH, topography minerals etc.

2. Biotic Components

The living organisms such as plants, animals and micro-organisms (Bacteria and Fungi) that are present in an ecosystem form the biotic components.

The biotic components can be further grouped into two basic components from the nutrition point of view:

(i) Autotrophic components, and

(ii) Heterotrophic components

The autotrophic components include all green plants which fix the radiant energy of the sun and manufacture food from inorganic substances. The heterotrophic components include non-green plants and all animals which take food from autotrophs.

Therefore biotic components can be described under following heads.

Producers: Among biotic components, at a basic functional level, ecosystem generally contains primary producers (plants) capable of harvesting energy from the sun through the process called photosynthesis. This energy then flows through the food chain.

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Consumers: After producers, next come consumers in the ecosystem. There are different classes or categories of consumers; these consumers feed on the captured energy.

(a) Consumers of the first order or primary consumers (herbivores): herbivorous are animals that are purely dependent for their food on producers or green plants. Insects, rodents, rabbit, deer, cow, buffalo, goat are some of the common herbivores in the terrestrial ecosystem and small crustaceans, mollusks, etc. in the aquatic habitat.

(b) Consumers of the second order or secondary consumers (carnivores): These are carnivores and omnivores. Carnivores are flesh-eating animals, and the omnivores are the animals that are adapted to consume herbivores as well as plants as their food. Secondary consumers are sparrow, crow, fox, wolves, dogs, cats, snakes, etc.

(c) Consumers of the third order or tertiary consumers: These are the top carnivores that prey upon other carnivores, omnivores and herbivores. Lions, tigers, hawk, vulture, etc. are considered as tertiary or top consumers.

(d) Parasites, scavengers and saprobes are also included in the consumers that utilize living tissues or dead remains of animals and plants as their food.

Decomposers: Decomposers work at the bottom of the food chain. Dead tissues and waste products are produced at all levels. Scavengers, detritivores (animals that live on the detritus of ecosystems) and decomposers not only feed on this energy but also break organic matter back into its organic constituents. It is the microbes that finish the job of decomposition and produce organic constituents that can again be used by producers.

The energy that flows through the food chain, i.e., from producers to consumers to decomposers is always inefficient. That means less energy is available at secondary consumers level than at primary producers level. It’s not surprising, but the amount of energy produced from place to place varies a lot due to the amount of solar radiation and the availability of nutrients and water.

Types of Ecosystem

There are very many types of ecosystems out there, but the three major classes of ecosystems, sometimes referred to as ‘biomes’, which are relatively contained, are the following:

  • Freshwater Ecosystems
  • Terrestrial Ecosystems
  • Ocean Ecosystems

Freshwater Ecosystems

These can be broken up into smaller ecosystems. For instance, in the freshwater ecosystems, we find:

  • Pond Ecosystems – These are usually relatively small and contained. Most of the time, they include various types of plants, amphibians and insects. Sometimes they include fish, but as these cannot move around as easily as amphibians and insects, it is less likely, and most of the time, fish are artificially introduced to these environments by humans.
  • River Ecosystems – Because rivers always link to the sea, they are more likely to contain fish alongside the usual plants, amphibians and insects.

These sorts of ecosystems can also include birds because birds often hunt in and around water for small fish or insects.

As is clear from the title, freshwater ecosystems are those that are contained in freshwater environments. This includes, but is not limited to, ponds, rivers and other waterways that are not the sea (which is, of course, saltwater and cannot support freshwater creatures for very long).

Freshwater ecosystems are actually the smallest of the three major classes of ecosystems, accounting for just 1.8% of the total of the Earth’s surface.

The ecosystems of freshwater systems include relatively small fish (bigger fish are usually found in the sea), amphibians (such as frogs, toads and newts), insects of various sorts and, of course, plants. The absolutely smallest living part of the food web of these sorts of ecosystems is plankton, a small organism that is often eaten by fish and other small creatures.

Terrestrial Ecosystems

Terrestrial ecosystems are many because there are so many different sorts of places on Earth. Some of the most common terrestrial ecosystems that are found are the following:

  • Rainforests – Rainforests usually have extremely dense ecosystems because there are so many different types of animals, all are living in a very small area.
  • Tundra – As mentioned above, tundra usually have relatively simple ecosystems because of the limited amount of life that can be supported in these harsh conditions.
  • Deserts – Quite the opposite of tundra in many ways, but still harsh, more animals live in the extreme heat than they live in the extreme cold of Antarctica, for instance.
  • Savannas – These differ from deserts because of the amount of rain that they get each year. Whereas deserts get only a tiny amount of precipitation every year. Savannas tend to be a bit wetter, which is better for supporting more life.
  • Forests – There are many different types of forests all over the world, including deciduous forests and coniferous forests. These can support a lot of life and can have very complex ecosystems.
  • Grasslands – Grasslands support a wide variety of life and can have very complex and involved ecosystems.
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Since there are so many different types of terrestrial ecosystems, it can be difficult to make generalizations that cover them all.

Because terrestrial ecosystems are so diverse, it is difficult to make generalizations about them. However, a few things are true almost all of the time. For instance, most contain herbivores that eat plants (that get their sustenance from the sun and the soil), and all have carnivores that eat herbivores and other carnivores.

Some places, such as the poles, contain mainly carnivores because no plant life grows. A lot of animals and plants that grow and live in terrestrial ecosystems also interact with freshwater and sometimes even ocean ecosystems.

Ocean Ecosystems

Ocean ecosystems are relatively contained, although they, like freshwater ecosystems, also include certain birds that hunt for fish and insects close to the ocean’s surface. There are different sorts of ocean ecosystems:

  • Shallow water – Some tiny fish and coral only live in the shallow waters close to land.
  • Deep water – Big and even gigantic creatures can live deep in the waters of the oceans. Some of the strangest creatures in the world live right at the bottom of the sea.
  • Warm water – Warmer waters, such as those of the Pacific Ocean, contain some of the most impressive and intricate ecosystems in the world.
  • Cold water – Less diverse, cold waters still support relatively complex ecosystems. Plankton usually forms the base of the food chain, followed by small fish that are either eaten by bigger fish or by other creatures such as seals or penguins.

Ocean ecosystems are amongst some of the most interesting in the world, especially in warm waters such as those of the Pacific Ocean. This is not least because around 75% of the Earth is covered by the sea, which means that there is lots of space for all sorts of different creatures to live and thrive.

There are actually three different types of oceanic ecosystems: shallow waters, deep waters and the deep ocean surface. In two of these, the very base of the food chain is plankton, just as it is in freshwater ecosystems. These plankton and other plants that grow in the ocean close to the surface are responsible for 40% of all photosynthesis that occurs on Earth.

There are herbivorous creatures that eat the plankton, such as shrimp, that are then usually eaten by bigger creatures, particularly fish.

Interestingly, in the deep ocean, plankton cannot exist because photosynthesis cannot occur since light cannot penetrate that far into the ocean’s depths.

Down in the deepest depths of the ocean, therefore, creatures have adapted very strangely and are amongst some of the most fascinating and the most terrifying and intriguing living creatures on Earth.

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Importance of Ecosystem

Ecosystems are communities of organisms and non-living matter that interact together. As ecosystems are interdependent, each part of the ecosystem is important. Damaged or imbalanced ecosystems can cause many problems.

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Components

Ecosystems are made up of soil, sunlight and heat, water, and living organisms, which include plants, animals and decomposers.

Interactions between components

Within an ecosystem, living organisms interact in different ways, including predation, cooperation, competition and symbiosis. Each species has a special role, such as converting sunlight to energy through photosynthesis, eating small insects, or decomposing matter.

Size of Ecosystem

The sizes of the ecosystems vary widely. They can be a puddle, a lake or a desert. Terrariums are artificial ecosystems.

Biomes

Biomes are composed of several ecosystems that are similar to each other. Biomes include tropical rainforests, deserts, tundra and grasslands.

Disturbances in Ecosystem

A small change in an ecosystem, such as the elimination or introduction of one species, can cause changes in the entire ecosystem. Environmental changes, as well as human interference, can cause these disturbances in the ecosystem.

Impact of Pollution

Pollution, including land, water and air pollution, poses a serious threat to ecosystems. Pollution can threaten or kill organisms that are vital for ecosystems, and the ecosystem can become imbalanced.

Function of Ecosystem

An ecosystem is a discrete structural, functional and life-sustaining environmental system. The functional components in any ecosystem are:

(i) Inorganic constituents (air, water and mineral salts)

(ii) Organisms (plants, animals and microbes), and

(iii) Energy which other components receive from outside (the sun).

These three form an environmental system and interact with each other. Inorganic constituents are synthesized into organic structures by the green plants (primary producers) through photosynthesis utilizing the solar energy in the process. Green plants become the source of energy for renewals (herbivores), which, in turn, become a source of energy for the flesh-eating animals (carnivores).

All types of animals grow by adding organic matter to their body weight, and complex organic compounds taken as food is their source of energy. They are known as secondary producers.

All the living organisms in an ecosystem have a definite life span, after which they die. The dead organic remains of plants and animals provide food for saprophytic microbes like bacteria, fungi and many other animals. The saprobes finally decompose the organic structure and break the complex molecules and liberate the inorganic components into the environment.

These organisms are known as decomposers. During the process of decomposition of organic molecules, the energy which binds the inorganic components together in the form of organic molecules gets liberated and dissipated into the environment in the form of heat energy.

Thus in ecosystem energy from the sun, the input is fixed by plants and transferred to animal components. Nutrients are withdrawn from the substrate, deposited in the tissues of the plants and animals, cycled from one feeding group to another, released by decomposition to the soil, water and air and then recycled.

The ecosystems operating in different locations, such as deserts, forests, grasslands and seas, are interdependent on another. The energy and nutrients of one ecosystem may find their way into another so that ultimately all parts of the earth are interrelated, each comprising a part of the total system that keeps the biosphere functioning.

References:

Ecosystem – Encyclopedia of Earth

Ecosystems – Encyclopedia

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