Biota And Their Environment – Download Notes of Biology Class 11

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Ozone LayerBotany | Biology
Download Notes on Biota and Their Environment
For: Science Class 11

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Forest Resources
The forest is very important renewable natural resources. About 37% land area of Nepal is occupied by forest. But according to unofficial record only 10% land area is occupied by forest.

Importance of forest

  • The source of raw materials
  • It provides timber fire wood which are used for various purposes like furniture, building houses etc it also provides fodder, different type of products like resin gum fiber tubers etc.
  • In Nepal fuel wood is only the source of energy for domestic cooking purpose.
  • The forest is being used as ayurvedic medicines drugs spices insecticides etc also used for extracting essential oils, which are used in soaps and cosmetics.
  • Various industries depend on forest for their raw material like paper plywood factories tanning materials like dyes gums resin obtained from plants are used in many industries
  • The forest plays a significant role in keeping the atmospheric balance by consuming coarbondioxide releasing oxygen. It also control pollution
  • The green plants are the primary source of energy for the other biotic components
  • The forest checks soil erosion and land degradation. The roots hold the soil. The forest stops the soil being eroded away by strong winds or rains.
  • The forest provides shelter to varieties of plats animals and microorganism.
  • Large numbers of people visit the forest for peace, beauty, and recreation. It provides natural beauty.

Types of forest in Nepal
The forest of Nepal is classified on the basis of geographical location and climatic characteristics.

  • Tropical forest: The forest found below 1000 meter from the seal level is tropical forest. It is found in terai belt. The forest of this belt is also called as Dun or Bhavar. The main forest is Sal Forest (Shorea robusta), Reverine, Decidious or evergreen forest is also found in this belt
  • Subtropical forest: the forest present between 1000 to 2000 meters from the ea level is subtropical forest. Below mahabharat range the Alnus, Schima, Pinus and Castanopsis forest are found in this belt
  • Temperate forest: the forest present between 2000 to 3000 meters from sea level is temperate forest. This range is also called mahabharat range, foothill, or lower Himalayan range. The Pinus, Rhododendron, Brich forest are found in this belt. Usually broad leave evergreen forest are found.
  • Sub alpine forest: the forest present between 3000 to 4000 meter from ea level is subalpine forest. This belt is also called as above mahabharat range or Himalayan range. Rhododendron, Birch, Silver and Fir Forest are found.
  • Alpine Forest: the forest present between 4000 to 5000 form the sea level is alpine forest. This range is also called as a high Himalayan range. Juniperous, Rhododendron forest are found in this zone

Aforestation
Plantation and selection of useful species, removal of undesired species, care, management and protection of forest, implementation of laws, utilization of forest education and activating the community and the people is called a forestation

Deforestation
It is characterized by loss or cutting of forest trees which brings s series of unfavorable changes in the whole biosphere. In the world 20.4 billion hector, forest is destroying per year. Among high rate of deforestation Nepal is one. 2.8 billion tons of CO2 is added in atmosphere per year by deforestation. In Nepal during 1965 to 1979, every year 70000 hector forest was destroyed. After 1979, every year 12000 hector forest was destroyed. After 2046 BS. 1200 hector forest was declared.

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