Ecosystem: Introduction, component and function

Introduction 

Ecology is the study of how different organisms or groups of organisms interact with their surroundings. Both biotic (living organisms) and abiotic (non-living organisms) elements make up the environment. Ecosystems are the subject of ecology. An ecosystem is a collection of organisms that communicate with one another and with their surroundings. The fundamental functional unit of ecology is an ecosystem. From a Greek word that means “study of home,” the word “ecosystem” was created. An ecosystem is a community of various species that are constantly exchanging matter and energy with one another as well as with their nonliving surroundings.

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Structure and Function of ecosystem

An ecosystem has two major components

• Biotic (living components)
• Abiotic (non living) components

Biotic Components

The biotic components of an ecosystem are the living things, such as plants, animals, and microorganisms (bacteria and fungi).

1. Producers (Autotrophs)

Green plants have chlorophyll, which allows them to capture solar energy and convert it into chemical energy in the form of carbohydrates using only two simple inorganic substances, namely carbon dioxide and water. Photosynthesis is the name given to this process. The green plants are referred to as autotrophs (auto = self, trophos = feeder) because they produce their own food. The producers use a portion of the chemical energy they have stored for their own growth and survival, and the remainder is stored in the plant’s constituent parts for later use.

2. Consumers (Heterotrophs)

The animals are unable to produce their own food because they lack chlorophyll. They therefore rely on the farmers to provide them with food. They are referred to as heterotrophs (heteros means other, feeder means feeder).

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The consumers are of four types, namely:

a) Primary consumers or First order consumers or Herbivores

These are the animals that consume producers or plants. They’re known as herbivores. Examples include cattle, goats, deer, and rabbits.

b) Secondary consumers or second order consumers or primary carnivores

Secondary consumers are primary carnivores, they feed on primary consumers. They directly depend on the herbivores for their food.

Examples: Frog, cat, snakes, foxes etc.

c) Tertiary consumers or third order consumers or secondary carnivores

Tertiary consumers are secondary carnivores, they feed on secondary consumers. They depend on the primary carnivores for their food.

Examples: Tigers, lions etc.

d) Quaternary consumers or fourth order consumers

These are the biggest carnivores that eat only tertiary consumers because no other animals will eat them. Lions and tigers are two examples.

3. Decomposer or reducer

This category includes bacteria and fungi. They decompose the dead organic materials that producers (plants) and consumers (animals) use as food, and they release back into the environment the straightforward inorganic and organic waste products of their metabolisms. The producers recycle these uncomplicated materials, which leads to a cyclical exchange of materials between the ecosystem’s biotic community and abiotic environment. Saprotrophs are the term for the decomposers (sapro means rotten and trophos means feeder).

Abiotic (nonliving) components

The non living components (physical and chemical) of the ecosystem collectively form a community called abiotic components or abiotic community.

Examples: Climate, soil, water, air, energy, nutrients etc.

• Physical components

They include the energy, climate, raw materials and living space that the biological community needs. They are useful for the growth and maintenance of its member

Examples: Air, water, soil, sunlight etc.

• Chemical Components

They are sources of essential nutrients. Examples:

Organic substances: Proteins, lipids, carbohydrates etc

Inorganic substances : All micro (Al, Co, Zu, Cu) and macro elements (C, H, O, P, N, P, K) and few other elements.

Function of an ecosystem

To understand clearly the nature of the ecosystem its functioning should be thoroughly understood. The function of an ecosystem is to allow flow of energy and cycling of nutrient

• Productivity
• Decomposition
• Physical (energy flow)
• Biological (Food chains, food web, ecological succession)
• Biogeochemical (nutrient cycling) processes.

a) Productivity

Any ecosystem must have a consistent solar energy input in order to function and maintain itself. The quantity of biomass or organic matter created by plants during photosynthesis per unit area over a given time is referred to as primary production. It can be quantified in terms of energy (kcal m-2) or weight (g-2). Productivity is the rate of biomass production. To compare the productivity of various ecosystems, it is expressed in terms of g-2 years or (kcal m-2) years. Net primary productivity (NPP) and gross primary productivity (GPP) are two ways to categorize it (NPP). The rate of organic matter production during photosynthesis is the gross primary productivity of an ecosystem. The biomass that is available for consumption by heterotrophs is known as net primary productivity (herbivores and decomposers).

b) Decomposition

It’s said that the farmer’s “friend” is the earthworm. They aid in both the loosening of the soil and the breakdown of complex organic matter. Similar to decomposers, decomposition is the breakdown of complex organic matter into inorganic elements like carbon dioxide, water, and nutrients. Detritus is the raw material for decomposition and includes dead plant remains like leaves, bark, flowers, and feces as well as dead animal remains. Decomposition involves several key stages, including fragmentation, leaching, catabolism, humification, and mineralization.

• Fragmentation: Detritivores reduce debris into smaller fragments, such as earthworms. This is the process of fragmentation.
• Leaching: Water-soluble inorganic nutrients are leached into the soil horizon and then precipitate as salts that are inaccessible to plants.
• Catabolism: Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is called catabolism. It is important to note that all the above steps in decomposition operate simultaneously on the detritus.
• Humification: Humification and mineralisation occur during decomposition in the soil. Humification leads to accumulation of a dark coloured amorphous substance called humus that is highly resistant to microbial action and undergoes decomposition at an extremely slow rate. Being colloidal in nature it serves as a reservoir of nutrients.
• Mineralization: Some microbes continue to break down the humus, and the process known as mineralisation results in the release of inorganic nutrients.

c) Energy flow

Energy flow and thermodynamics

The flow of energy through an ecosystem follows the two laws of thermodynamics

1. I law of thermodynamics

It states that energy can be created nor destroyed but it can be considered from one form to another.

2. II law of thermodynamics

It states that “whenever energy is transformed, there is loss of energy through the release of  heat.”

d) Biological

Food Chains

The term “food chain” refers to the chain of organisms that transfers food energy from producers to consumers, including herbivores, carnivores, and decomposers.

There are two types of food chains:

(i)Grazing food chains: Grazing food chains begin with green plants, which produce food for herbivores, who in turn provide food for carnivores. This kind of food chain in ecosystems is utterly dependent on solar radiation.

(ii) Detritus food chains: Dead organic matter is the first link in the detritus food chain, followed by detritivore organisms that produce food for protozoans, carnivores, etc.

Food web

A food chain only traces one path of food, whereas a food web depicts all potential transfers of energy and nutrients among the organisms in an ecosystem. Food webs play a crucial role in preserving an ecosystem’s stability.

Ecological succession

Ecological succession refers to the gradual and largely predictable change in the species composition of a particular area. During succession, some species colonize a region and see an increase in population, while other species see a decline or even extinction of their populations. A sere is the collective term for all of the communities that successively change in a particular area (s). Seral stages or seral communities are the names given to the various transitional communities.

e) Biogeochemical Processes

Cyclic exchange of material between the living organisms and their nonliving environment is called the Biogeochemical Cycle.

Nutrient cycle are of two types: (a) gaseous(nitrogen cycle & carbon cycle) and (b) sedimentary (sulfur & phosphorus cycle)

Types of ecosystem.

Natural ecosystems operate themselves under natural conditions.

Based on habitat types, it can be further divided into three types

1. Terrestrial ecosystem

This ecosystem is related to land. types: Grassland ecosystem, forest ecosystem, desert ecosystem etc.

2.  Aquatic ecosystem

This ecosystem is related to water. It is further sub classified into two types based on salt content.

• Freshwater ecosystem

i)Running water ecosystem: examples: River, Streams

ii) Standing water ecosystem: examples: Pond, lake

• Marine ecosystem: Examples: Seas and sea shores

3. Man made artificial ecosystem

Artificial is operated or maintained by man himself.

Examples: Croplands, gardens

References

Balasubramanian, A. (2008). Ecosystem and its components. Earth Science, 12(7), 1–7.

Flow, E., Pyramids, E., Succession, E., Cycling, N., & An, E. S. (2022). Ecosystem 14.1.

MEPA. (2004). 1. Soil. 1–9.

Samadhiya, D. H. (2015). Topic: Ecosystem: Structure and Types Paper: 402 Ecology and Animal Behavior Dr. Hemant Samadhiya. Ecosystem: Structure and Types.

Singh, A. K., & Singh, D. (2019). • Unit-2 Ecosystems Unit 2. 1–21.

Tsujimoto, M., Kajikawa, Y., Tomita, J., & Matsumoto, Y. (2018). A review of the ecosystem concept — Towards coherent ecosystem design. Technological Forecasting and Social Change, 136(December 2015), 49–58. https://doi.org/10.1016/j.techfore.2017.06.032

W.F.J., C. (1989). What is a healthy food? Food Chemistry, 105–115.

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Ecosystem: Introduction, component and function