Important Notes for CBSE Class 7 Science Chapter 17 – Forest: Our Life Lines. Forest: Our Life Lines Class 7 Notes and Study Material Download in PDF form.
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Forest: Our Life Lines Class 7 Notes
- Forests are one of the richest sources of natural recourses.
- They supply oxygen and a natural water purifying system.
- Forests appear lush green with a vast green cover over the land.
- The distribution of the forest cover is not uniform.
- Forest environment is cool and peaceful.
- A large number of bird and animals like boar,bison, jackals, porcupine, elephants’ monkeys, also inhabitate the forest.
- The trees like sal, teak, semal, sheesham, neem,palash, fig, khair, amla, bamboo,kachnar are found in forests.
- Shrubs, herbs, creepers, climbers and grasses are also found on forest floor.
- In deep forest sunlight does not reach the leaves of the trees, makingit quite dark inside the forest.
- Different household items are obtained from material which are obtained from the forest.
- Wooden items such as plywood, fuel wood, boxes, paper, matchsticks, furniture, gum, oils,spices, fodder for animals and medicinalplants are some products obtained from forest.
- In these forests trees produce enoughseeds which germinate on the forest floor and grow up in trees.
- Canopy is a large roof like structure of branches of tall trees.
- Different treeshave crowns of different types and sizes creating a diverse horizontal layer in the forest called understories.
- Varied climatic conditions lead to generation of different types of trees and other plants. Different animals are fond in different forests.
- The ground surface is a place where numerous insects,spiders, squirrels, ants and variousother small animals reside.
- The forest floor is darkcolored due to formation of humas.
- Autotrophs, heterotrophs and saprotrophs are all found in forest.
- Autotrophs produce their own food. All animals be it herbivores or carnivores, depend ultimately on plants for food.
- Saprophytes feed on dead decaying matter.
- Food chain are part of the forest.
- All the food chains are interlinked and if anychain is disturbed, it affectsother food chains also.
- Microorganisms are also a part of forest soil and utilize dead plant and animal tissuesand convert them into a dark colored substance called humus.
- They are called as decomposers.
- Humus provides nutrients to the soil which are absorbedby the roots of the living plants.
- Dead animals become food for vultures, crows, jackals and insects.
- Forest is known as green lungs, where plants release oxygen through the process of photosynthesis.
- The plants provide oxygen for animal respiration and maintain balance of oxygen and carbon dioxidein the atmosphere
- Trees absorb water from their roots and release water vapors into the air through transpiration.
- Many people living in the forest belong to different tribesprovidesthem with food, shelter, water and medicines.
- Animals like deer drink water from surrounding stream and on sensing any danger disappear into the bushes.
- The tall grass provides animals with the food and shelter and protect them from carnivores.
- Animals in the forest can be identified by their droppings and footprints.
- Animals disperse seeds ofplants and help forest to growand regenerate.
- The wide variety of animals helps the forest to regenerate and grow.
- Decomposers maintain the supply of nutrients to the growing plantsin the forest.
- When it rains the rain water does not hit theforest floor directly.
- The forest canopy prevents the flowof raindrops and water coming down through the branches and stems of trees.
- The ground is comparatively drier.
- Water does not stagnate the forest and acts as a natural absorber ofrainwater and allows it to seep.
- It helps to maintain the water table throughout theyear.
- Forest help in controllingfloods and helps in maintaing the flowof water in the streams
- Deforestation leas to soil erosion.
- Noise pollution is also reduced due to forests.
- Construction of roads, buildings, industrial development and increasing demand of wood creates pressure on the forests and increases in deforestation.
IMPORTANCE OF FOREST:
- Forests gives us oxygen.
- Forest prevents soil erosion and provide shelter to a large number of animals.
- Forests increase rainfall in neighboring areas.
- Forest provides us with medicinal plants, timber and many other useful products.
- Deforestation increases the amount of carbon dioxide in air and also increases the temperature.
- If trees are cut plants, animals will not get food and shelter, soil will lose its water retionsion and cause floods.