Question 1 What are decomposers? Give example?
Question 2 What is the crown of a tree? What are its major function?
Question 3 What are scavengers? What is the role of scavengers in forest?
Question 4 How do trees grow in a natural forest?
Question 5 Explain why there is no waste in a forest?
Question 6 Give one example of a food chain taking place in a forest?
Question 7 Explain how decomposers help in maintaining the supply of nutrients to the growing plants in a forest?
Question 8 How does forest act as purifier of air and water?
Question 9 Explain the components of forest?
Question 10 Define the term ecosystem?
A forest is a large area of land covered mainly with trees, and other plants. Due to different climates and soils, there are variations in the types of trees and other plants found in various forests.
Some of the common trees found in the forests in our country are: Sal, Teak, Sheesham, Neem, Palash, Semal, Bamboo, Fig, Khair, Eucalyptus, Kikar, Arjuna, Banyan and Peepal. Some of the forest trees are also covered with different types of creepers and climbers.
There are several other trees, shrubs, herbs, creepers, climbers and grasses in the forest.
The natural forest trees grow on their own. In nature , the trees produce enough seeds. These seeds fall on the forest floor. The forest floor provides favourable conditions (nutrients, water, warmth, etc.) for these seeds to germinate into seedlings and saplings. Some of these saplings grow into big trees. The shrubs and herbs also grow in the forest on their own in a similar way.
The forest also has a wide variety of animals. The type of animals also differ from forest to forest. Some of the common animals which are found in forests in our country are : Monkeys, Boar (Pig), Jackal, Bison, Elephants, Tigers, Lions, Deer, Rabbit, Ape, Porcupine, Squirrel, Peacock, Toucan, Frog, Bat, Owl, Rats, Snakes, Butterflies, Insects, Spiders, Ants, Honeybees, and various other small animals. The insects, butterflies, honeybees, and birds help the flowering plants of the forest in pollination. The forest also contains decomposer organisms (or micro-organisms) such as bacteria and fungi. The fungi found in forest are mushrooms, toadstools and puffballs.
A forest acts as the purifier of air and water. The forest acts as a purifier of air because the leaves of its trees and plants clean the air by trapping dust from the air. It also puts oxygen in air. The forest acts as purifier of water because its trees may suck dirty water from the soil through their roots and make pure water available as rain (through the water cycle).
Components of a Forest
The living organisms in a forest are plants, animals and decomposers.
The non-living environment in a forest consists of soil, water and air.The non-living environment of a forest provides nutrients, water and carbon dioxide for the growth of plants.
(1) Plants: A forest has many green plants. The green plants produce food by photosynthesis (by absorbing nutrients and water from soil, and carbon dioxide from air). So, the plants are called producers (of food).The green plants provide food to all the animals in the forest, directly or indirectly.
(2) Animals: The animals are called consumers (of food). The animals in the forest may be herbivores (plant eating) or carnivores (flesh eating). All the animals of the forest, whether herbivores or carnivores, depend on plants for food, directly or indirectly. The animals are also called heterotrophs (because they depend on other organisms for food)
(3) Decomposers: The living organisms such as certain bacteria, and fungi (mushrooms and toadstools, etc) which live and feed on dead plants and animals are called saprotrophs. Saprotrophs are commonly known as decomposer.
The decomposers play a very important role in sustaining the forests. After a certain period, the plants and animals die. The micro-organisms which break down the dead parts of plants and dead bodies of animals into simple substances such as mineral salts (or nutrients), carbon dioxide and water, which can be re-used by the plants, are called decomposers. The micro-organisms such as bacteria and fungi are decomposers. Bacteria and fungi are non-green organisms which cannot make their own food. They obtain their food from the dead parts of plants and dead bodies of animals. During the process of obtaining food, the bacteria and fungi decompose the matter present in the dead plants and animals into mineral salts, carbon dioxide and water. The mineral salts thus formed are called nutrients (for plants). The mineral salts (or nutrients) formed in this way mix with the soil of the forest. They make the soil fertile. These nutrients in the soil can be used again by the plants for their growth. The decomposers break down the animal waste into mineral salts which go into the soil as nutrients for plants.
The importance of Decomposers
(1) Decomposers return the nutrients present in the dead plants, dead animals, and animal wastes to the soil . In this way, decomposers help in maintaining the supply of nutrients to the growing plants in the forest.
(2) By carrying out decomposition, decomposers prevent the dead plants, dead animals, and animal wastes from piling up in the forest.
When decomposers (like bacteria and fungi) feed on dead plant parts, dead animals, and animal wastes (like animal dung and droppings), they convert them into a dark coloured substance called humus. This humus contains the mineral salts. When this humus mixes with forest soil, the soil gets nutrients. From the soil these nutrients are again absorbed by the roots of living plants.So, the importance of humus to the soil is that it provides nutrients for the growth of plants.
Those animals which eat the dead animals are called scavengers.
Vultures, crows, jackals , hyena , some insects, ants, beetles, termite, woodlouse, maggot, millipedes, and earthworm eat dead animals, so they are also scavengers.
Scavengers eat up the dead bodies of animals and help in keeping forest environment clean. Without scavengers, dead bodies of forest animals could not be got rid of quickly. Scavengers are not decomposers. They do not break down dead animals into simple substances which can be reused by the plants.
When the animals die in a forest, they are eaten up by some other animals called scavengers. The decomposer organisms (bacteria and fungi) decompose the dead plant material, dead animals and animal wastes present in the forest into mineral salts (in the form of humus), water and carbon dioxide, which go into soil and air (and hence recycled for the growth of plants).Since dead animals are eaten up, and the materials present in dead plants, dead animals and animal wastes are recycled, therefore, there is no waste left in a forest.
Forest is an Ecosystem
An ecosystem is a self-sufficient unit of living things and non-living environment needing only the input of sunlight energy for its functioning. In the forest ecosystem, there is an interaction between the living things and non-living environment.
(1) The living organisms like plants interact with soil to obtain nutrients (like mineral salts) for their growth. The plant interact with water (in soil and water bodies) to get water for making food by photosynthesis. And plant also interact with air to obtain carbon dioxide for making food by photosynthesis.
(2) The living organisms like plants and animals interact with, one another through their food chains in which one organism eats another organism. Grass is a kind of plant. In a forest, grass (or plant) is eaten by insects (such as grasshopper), the insects are eaten by frogs, the frog is eaten up by snake, and finally, the snake may be eaten up by an eagle. So, a common food chain occurring in a forest habitat is
Grass ——> Insect(Grasshopper)——->Frog—–> Snake—–> Eagle
Many different food chains can be found in a forest. All the food chains in a forest are inter-linked to form a food web. If any food chain web is disturbed, it affects many other food chains.
(1) Food chain in the forest starts with plants (grass or other plants). This is because the plants are producers of food. They are autotrophs. So, the first step in every food chain is the plants.
(2) The plants are eaten up by the animals called herbivores. So, the second step in a food chain is always herbivore (or herbivorous animals).
(3) The herbivores (animals which eat plants) are eaten up by the animals called carnivores (which eat meat). So, the third step in a food chain is always a carnivore (or carnivorous animal). But it is a small carnivore.
(4) The small carnivore is eaten up by a large carnivore. And the large carnivore is eaten up by a still larger carnivore called top carnivore.
(5) The green plants (autotrophs) take nutrients and water from the soil, carbon dioxide from air and energy from sunlight, and make food by photosynthesis. The plants are eaten as food by herbivores. Many herbivores are eaten as food by various carnivores. In this way, food is transferred from plants to various types of animals through the food chains occurring in a forest.
(6) When plants (autotrophs) and animals (heterotrophs) die, then the decomposer organisms decompose their dead bodies into nutrients, water and carbon dioxide. Nutrients and water are returned to the soil, and carbon dioxide is returned to the air. These nutrients , water and carbon dioxide are then reused for the growth of new plants in the forest. And this process goes on and on like an unending chain.
Crowns of Trees
The branchy part of a tree above the stem is known as the crown of the tree. Different types of trees have crowns having different shapes and sizes. There are a large number of crown shapes of trees in a forest.
The major function of the crown of a tree are to absorb sun’s light energy, carry out photosynthesis, release oxygen and carry out the process of respiration and transpiration. The crowns of tall trees form a green cover over the forest land. And the trees and plants of different heights create different horizontal layers in the forest. The crowns of trees shade the forest floor.