Ecosystem

Q.1. Define Ecosystem. Explain its structure and function. 

Ans. Introduction: The interactions between abiotic components (non-living) like water, soil, air and climate and biotic components (living creatures) like plants, animals and microbes is called as an Ecosystem. Eco means environment and system refers to the interaction between various components. 

(a) Abiotic Components: Abiotic components include non-living substances which can again be divided into (1) Climatic and (2) Edaphic:

(i) Climatic: Climatic components include rain, light, wind and temperature. 

(ii) Edaphic Components: Edaphic components consist of soil, pH value, minerals and topography. This can be further divided into (i) Organic Components and (ii) Inorganic Components.

(b) Biotic Components: Biotic components of an ecosystem include:

(i) Producers/Autotrophs: Producers are those living organisms which convert solar energy to chemical energy in order to make food. Using sunlight, water, soil and chlorophyll, plants and some food producing bacteria make food through a process called as photosynthesis. 

(ii) Consumers/Heterotrophs: Heterotrophs are animals which cannot create their own food and hence depend on autotrophs for their energy requirements. Consumers can be further broken down into:

- Primary Consumers/Herbivores: Animals which depend directly on producers are called as herbivores. E.g. cows, horses, deer etc. Secondary Consumers/Primary 

- Carnivores: These animals depend upon primary consumers or herbivores. E.g.: Cats, dogs, snakes etc.. Tertiary Consumer/Large Carnivores: These animals feed on secondary consumers. Eg.: Sharks, wolves, hyenas.

- Omnivores: Omnivores feed on both producers and primary consumers.

Eg Human beings Eg.

(iii) Decomposers: These creatures feed on dead bodies and break them down into smaller substances which then act as nutrients and improve soil quality. Eg. Snails, slugs, bacteria.

Functions of an Ecosystem Functional aspects of an ecosystem include:

(i) Energy cycles: Energy cycles are based on the principles of converting one form of energy to the other. For example, energy from sunlight is converted into energy for plants to grow leaves. This energy in turn can be utilised by herbivores as food.

(ii) Food Chains: Food chains can be defined as the flow of energy from one organism to the other. For example, grass is eaten by grasshopper which is in turn eaten by a frog. A food web is a complex interconnection between several individual food chains.

(iii) Diversity interlinkages: Diversity linkages states that no two species can occupy the same niche (food or space) successfully in a stable community. Closely related species therefore live far from one another, thus leading to diversity in one ecosystem. This is because plants and animals must compete for w water, nutrients, light and space. The outcome of this competition determines the character of an ecosystem.

(iv) Nutrient cycles: Processes through which elements that sustain life (water, carbon, phosphorus and nitrogen) are continuously made available to living organisms. 

- Nitrogen Cycle, 

- Hydrological cycle,

- Carbon cycle,

- Phosphorus cycle

(v) Evolution: The process by which different kinds of living organism are believed to have developed from earlier forms during the history of the earth. In each ecosystem, organisms keep developing each day and adapting to new situations leading to their evolution.