Introduction
Earth is the only planet in the ecosystem that has life on it. The Earth consists of the following layers Lithosphere: The outer solid layer, the source of minerals and soil. Soil provides nutrients essential for plants. Hydrosphere: The aquatic envelope of the Earth. 70% of Earth's surface is covered with water. Atmosphere: The envelope of gas that surrounds the Earth. It contains gases, such as nitrogen, carbon dioxide, oxygen, and traces amounts of neon, helium, methane, krypton, and water vapour. When these 3 layers interact with each other for life to exist, the part of the Earth, where life exists is called the Biosphere.
Understanding Ecosystem
The Earth is home to plants and animals. The natural surroundings in which a living thing survives is its Environment. These living things interact with one another and their surroundings. This interaction of the living things with their physical environment forms an Ecosystem. Common examples of ecosystems are pond, lake, river, marine, desert, grassland and forest. The term ecosystem is derived from the Greek word 'Oikos' meaning 'a house'.
Components of Ecosystem
Biotic components: Biotic components include all living organisms such as plants, animals and micro-organisms. These living organisms influence each other's life directly or indirectly. The biotic components can be further divided based on their food habits and how they obtain their food in the environment.
Producers: Producers are organisms that produce their own food. These are also called autotrophs (auto means self and trophs means food). Producers are thus the main source of food for all organisms. They take carbon dioxide from the air and water from the soil and prepare their food in presence of sunlight. This process of converting solar energy into chemical energy is known as Photosynthesis. Plants and algae are examples of producers.
Consumers: Consumers are living organisms that cannot make their own food and depend on plants or other animals. They are known as heterotrophs (hetero means other and trophs means food).
Herbivores: These organisms depend directly on plants (producers) for their food and energy. They may eat grasses, leaves, grains, fruits r bark of trees. Herbivores are also called Primary Consumers. Example: cow, buffalo, goat.
Carnivores: Some animals eat other living animals. They do not eat plants at all. They eat the meat (flesh) of their animals. These animals are known as carnivores. Carnivores that eat herbivores are also known as Secondary Consumers. Example: frog, lizard and snakes. There are certain carnivres that eat ther carnivres. They are called Tertiary Consumers. Example: lion, tiger, birds of prey (such as hawk).
Humidity: Moisture present in the atmosphere in the form of water vapour is known as Humidity.
Food chain and food web
Food Chain
1) The feeding relationship between different organisms through which energy is transferred step-by-step from the producers to the consumers is called the food chain.
2) In the typical food chain, the producers (green plants) are eaten by the primary consumers (herbivores)
3) The primary consumers are eaten by the secondary consumers (carnivores), which are eaten by tertiary consumers.
4) This sequence of eating and being eaten results in a chain called the food chain.
5) In a food chain, as the food gets from one level to the next, there is also the transfer of energy at each food chain level. The flow of energy in a food chain is always unidirectional.
Different habitats have different food chains:
Aquatic food chain - The weeds in the water are eaten by the small fish and the small fish in turn are eaten by big fish. This makes an aquatic food chain.
Food Web:
However, in nature, the same plants and animals can be eaten by more than one organism. Several food chains are found.
For example, rats can be eaten by snakes and by owls. Likewise, an animal need not feed only one type of food. For example, a lion can feed on a fox, wildcat, or goat. Thus, we see that there are a lot of food chains that prevail in an ecosystem that are interconnecting, overlapping ad interdependent where one organism may occupy positions in more than one food chain. This creates a complex, web-like pattern of multiple food chains connected naturally, known as the food web.
Ecological pyramid: A graphical representation of the number f organisms, biomass and productivity at each trophic level in an ecosystem is called an ecological pyramid. Ecological pyramids represent the structure of an ecosystem.
Forest ecosystem: A forest is a large area of land covered by trees and other plants growing close together. The biotic component of a forest ecosystem consists of different varieties of plants and animals.
Types of forests and their flora and fauna:
Forests form the dominant terrestrial ecosystem of the Earth and are found across the globe. They cover nearly one-third of the planet. Depending upon their location forests are of the 3 main types-tropical, temperate and boreal forests.
Tropical rainforests:-
Flora: Evergreen trees with broad leaves form the major vegetation of tropical rainforests. Trees are tall and form the canopy layer. Epiphytes grow on trees. Orchid, fern, rubber tree, rosewood tree, the mahogany tree, palm tree, bamboo tree, cycads, along with spice trees such as clove and cinnamon are found in the forests.
Boreal forest:-
Flora: Coniferous trees such as pine, spruce and larch are common in these forests. These trees bear cones that contain seeds. They have needle-shaped leaves.
Fauna: Animals such as moose, reindeer or caribou, deer, elk, beaver, squirrel, wolf, fox, wood bison and chipmunk are found here.
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