Forests: Our Lifeline PDF

# Forests: Our Lifeline ## Chapter 8 ## Introduction * About one-third of the world's land surface is covered with forests. * Forests are different from one another depending upon where they are located. * Climate, topography and soil type are some of the main factors that determine the type of t...

# Forests: Our Lifeline ## Chapter 8 ## Introduction * About one-third of the world's land surface is covered with forests. * Forests are different from one another depending upon where they are located. * Climate, topography and soil type are some of the main factors that determine the type of trees and animals that grow and thrive in a forest. ## Forest profile * In a forest, many different trees like those of teak, sal, shisham, kachnar, amla, neem, palash, khair and bamboos are found. * In addition to trees, shrubs, herbs, climbers and creepers are present in a forest. * A forest area may have a dense growth of trees. * The forest floor is quite dark as the sun is not able to penetrate through the leaves of the trees. * Such a shaded forest floor provides habitat for the growth of mosses, lichens and other shade-loving plants. * The branches of trees in a dense forest form a cover or roof over the other plants in the forest. * Such a cover or roof formed by the tree branches in the upper regions is called a canopy. * The branchy part of a tree above the stem is known as the crown of the tree. * Shapes and size of the crown differ in different trees. * Based on the height of trees, different horizontal layers are created in the forest. * These horizontal layers present at different heights below the canopy are known as understorey. * Tall trees form the canopy, followed by small trees and shrubs, which form the understorey, and the herbs or ground flora which forms the lowest layer of the understorey. ## Uses of forest 1. **Food** * Cereals: Rice, wheat, maze, barley etc. * Pulses: Moong, gram, pea, urad, arhar etc. * Vegetables: Onion, potato, spinach, brinjal, radish, carrot, beetroot etc. * Fruits: Mango, apple, banana, grapes, pineapple, orange etc * Beverages: Tea, coffee etc. * Sugar: Sugarcane * Spices: Turmeric (haldi), pepper, chilli, clove (loung) etc. * Oil seeds: Groundnut, coconut, mustard etc. 2. **Clothing:** We also get fibre from plants, such as cotton, jute, linen, hemp, flux, and ramie, which grow in forests. 3. **Medicines:** Most of the medicines are obtained from plants. * Penicillin: Fungus Penicillium * Quinine: Bark of Cinchona (cure for malaria) 4. **Timber or wood:** (Furniture, housing, ship etc.) * Trees such as sal, mahogany, teak, and rosewood. We also get firewood from trees. 5. **Paper:** Wood pulp of bamboos and eucalyptus. 6. **Rubber:** (For tyres, shoes, mattresses, etc.) 7. **Resins, Bamboo, Cane:** Forests are also a source of resins (used to make varnish and paint); latex (used to make rubber); bamboo (useful as fodder, and serves as an important raw material for the manufacutre of paper and pulp, basket and other small-scale industries); and cane (used to make walking sticks, furniture, baskets, picture frames, screens and mats). 8. **Fuel** 9. **Ornamental and landscape purposes** * A number of plants are grown in gardens and other places for aesthetic beauty. ## Other uses 1. **Plants prevent soil erosion by wind or water.** Removal of plants (defores-tation) leads to soil erosion. Plants serve the purpose of binding the soil with the help of their roots. 2. **Certain plants like legumes enrich soil fertility.** ## Oils * Many varieties of grasses such as lemon grass, vanilla, kewra, and khus are the sources of several kinds of essential oils. * Sandalwood, eucalyptus and pine also give us oil, which can be extracted from the wood of these trees. * These oils are used in making soaps, cosmetics, incenses, medicines and as an essence for flavour and smell in bakeries and confectioneries. ## Check your concepts 1. How are floods caused? 2. Why there is an increase in earth's temperature? 3. What helps forests to grow and regenerate? 4. What is meant by canopy? ## Building concepts ### Interdependence of plants and animals * Living organisms are all interconnected and form a biotic community or biota. * Forests help to conserve the diverse life forms or living organisms around the world. * Plants prepare their own food and are called producers (autotrophic nutrition). * Animals cannot produce their own food and have to consume plants or other animals to live and grow. Therefore, they are called consumers. * Consumers may be herbivores or carnivores. * Herbivores are animals which eat only plants. * Some animals eat only other animals. They are called carnivorous animals. * There is another category of animals, called omnivorous animals. These animals eat both plants and animals. ### Explain why there is no waste in a forest? * The forest floor is often littered with fallen decaying leaves, twigs, fruits and seeds. * It is dark coloured and many saprophytic micro-organisms like fungi and bacteria grow on dead and decaying matter. * They convert the dead plants and animals to humus and thereby return the nutrients to the soil. ## Food chain and food web * **Food chain:** All animals depend on plants for food, directly or indirectly. * For example, a rat eats grains and plants, a snake eats a rat, which is in turn eaten by an eagle. * It is like a chain that exists in nature. * Such a chain is called a food chain. * Green plants are called the producers as they can produce their own food. * Animals are called consumers since they cannot produce their own food and depend on plants and other animals for food. * When animals die, their bodies breakdown (with the help of decomposers such as bacteria and fungi) and become a part of the soil. * This makes the soil fertile helping in the growth of plants. * These plants again become food sources for the animals. * Thus, the food chain goes on and on. * Food chains are simple representations of energy flow in nature. * They exist everywhere, be it in the ocean, the grassland, desert, or the mountain. * **Food web:** Interconnected food chains depicting the complex representation of energy flow in nature is called food web. * Several food chains that exist in nature are interconnected. * For example, a rat and a hen both eat grains. * Both of them can be eaten by a cat. * A cat can be eaten by a bigger animal such as a wolf. * But a wolf can also eat a hen and a rat directly. * **Scavengers and decomposers:** You might have seen vultures or crows eating dead animals. * Animals that eat dead animals are called scavengers. * Dead plants and animals, fallen leaves, left-over food material rot after some days. * This process of rotting is called decomposition. * Certain living organisms like bacteria and fungi help in this process. * Such organisms are called decomposers. * Decomposers break down the organic matter of dead organisms into simple nutrients in the soil. * This matter is called humus. * From the soil, the nutrients are again absorbed by the roots of plants. * In this way, cycling of nutrients takes place. * Thus, a forest is a dynamic living entity, as it consists of living organisms of different kinds performing different roles. * **Balance in nature:** * For a living thing to survive, it must exist in a certain proportion and allow other living things to exist. * Living things cannot afford to exist without any check. * For instance, if there are too many lions, they will kill all the deer. * On the other hand, if there are too many deer, they will eat too much grass, and not leave any grass for the other animals. * Thus, different living organisms must exist to survive. ## Check your answers 1. In the absence of trees, soil is not able to hold water. As a result, floods are caused. 2. When forests disappear, the amount of carbon dioxide in air will increase, resulting in increase in earth's temperature. 3. Soil helps forests to grow and regenerate. 4. Canopy is the branches of the tall trees look like a roof over the other plants in the forest. ## Building concepts ### How does forests help in purifying air? * Forests are rich in plants and animals. * All plants and animals take in air to survive. * As we know, green plants take in carbon dioxide of the air to manufacture their own food (photosynthesis) and release oxygen as a by-product. * Forests also serve as a sink for carbon dioxide given out by plants and animals during respiration, produced by burning coal and petroleum, given out as a result of volcanoes and other natural disasters. * Thus, forests help to maintain the levels of oxygen and carbon dioxide of the air. * Forests, especially rainforests, are referred to as the 'lungs' of the Earth. ## Dependence of animals on plants * Animals depend upon plants in various ways: * **For Food:** All animals depend for their food, directly or indirectly, on green plants. * **For Oxygen:** Plants give out oxygen during the process of photosynthesis. The oxygen, so liberated, is used by animals and plants for their respiration. * **For Shelter:** Some animals depend on plants for shelter. They make their homes in holes of the trees. Some birds build their nests in the trees. Many insects like grasshoppers, moths, ants, beetles etc, live in trees. Monkeys also live on trees. ## Dependence of plants on animals * **For Carbon dioxide:** Plants need carbon dioxide to prepare food through photosynthesis. This carbon dioxide comes from animals during respiration. * **For Pollination:** In some plants, pollination is brought about by insects, birds and bats. Without pollination, formation of seeds in these plants would not be possible. * **For Seed dispersal:** Seed dispersal in many plants is through animals and even man. Fruits are eaten by animals such as the birds who carry them to distant places. Finally, the seeds are passed out in their excreta without any damage. * **Some seeds possess spines or hooks which enable them to stick to the body of animals and thereby helping them being carried from one place to the other. Finally, man himself is a great disseminator of seeds, especially of those which he uses, for his food and other needs.** ## If forests disappear * We have learnt how forests are important to all living beings on the Earth. * But what if these forests get destroyed? * With the increase in human population, there have been ever-rising demands for converting forests into residential and agriculture areas. * As a result, lots of trees are being felled and forests cleared, thus destroying the habitat of several species of animals and plants. * Such large-scale falling of trees is called deforestation. **Deforestation is the permanent destruction of forests and woodlands.** 1. If forests get destroyed, global climate and local weather may change drastically. This will result in the loss of many species of animals and plants, and biological diversity. 2. Large amounts of greenhouse gases such as carbon dioxide are released into the atmosphere due to deforestation. 3. Natural resources such as timber, medicinal plants, fruits and nuts are depleted due to deforestation. 4. Deforestation can cause severe flooding, soil erosion, landslide, etc., affecting our day-to-day life. Our forests need to be protected from further depletion. ## Check your concepts 1. What happens if an animal dies in the forest? 2. How do clouds form? 3. Why do tribals mostly depend on the forests? ## Conservation of forests * Prevention of further depletion of forests is called conservation of forests. * Few measures that could be followed to conserve our forests are given below: 1. **Afforestation:** People living near forest areas should be made aware of the damages caused by felling of trees. They should be encouraged to cut branches, twigs, and leaves of the trees to meet their everyday requirements instead of chopping down the full-grown trees. Government and communities should take steps to plant trees on a large scale. Trees that will meet the basic requirements of fuelwood, fodder and timber should be planted instead of falling the existing ones. 2. **Planned cultivation:** People should be made aware that a forest should not be cleared of all its trees and converted to an agricultural land, as this can lead to soil erosion. 3. **Prevent illegal logging:** Illegal logging has led to the decrease of a lot of trees over the years. The Indian government has laid out rules to prevent illegal logging by making it punishable under law. 4. **Prevent overgrazing:** Provision of sufficient pasture should be made, especially in areas adjoining forests, to prevent overgrazing of growing plants by cattle. 5. **Protection from forest fires:** Forest fires can occur as a result of careless human activities, such as debris burning and campfires and lightning. These might cause damage to nearby housing and agricultural land. Forest fires are considered beneficial for plants but they might have devastating effects on the animal life and people living nearby. These forest fires can be prevented by being careful in burning debris. Fire retardants and water bombs are also used to prevent forest fires. ## Check your answers 1. If an animal dies in the forest, it becomes food for vultures, crows, jackals and insects. As a result, nutrients are recycled and nothing goes waste in a forest. 2. Trees take in water from their roots and release water vapour into the air through evaporation as a result, clouds are formed. 3. The forests provide food, shelter, water and medicines for tribals. Tribals have traditional knowledge about many plants. Therefore, they mostly depend on the forests.