Importance of Forests, Effects of Deforestation, Practice Problems and FAQs

Have you read Rudyard Kipling’s famous creation ‘The Jungle Book’? The book is a work of fiction and tells us a story about a child being raised by wolves and loved by other animals. As a child this was my first introduction to the world of jungles and it fascinated me. Forests or jungles have always been a mystery to mankind because although a forest looks very peaceful and content from the outside, it can have many lurking dangers inside as forests are home to some of the most lethal predators of our planets. But, forests are also the home to millions of trees which are the major producers of oxygen in the terrestrial ecosystems. No wonder the Amazon rainforests, being one of the largest forests of the world, are said to be the earth’s lungs.

But is that the only way the forests contribute? What would happen if the forests are cut down for human needs? Will that affect us? Will that affect the ecosystem? Let us discuss the answers to these questions in this article

Table of contents

• Introduction to forests
• Structure of a forest
• Types of Forests
• Importance of forests
• Deforestation
• Conservation of forests
• Practice Problems
• FAQs

Introduction to forests

A land area which predominantly houses tall trees is said to be a forest. According to The United Nations' Food and Agriculture Organisation (FAO) any land that spans an area of more than 0.5 hectares and is covered by trees having a height of at least 5 metres or higher and providing a canopy cover of at least ten percent, can be considered a forest. It excludes any land that is used for agricultural or urbanisation processes.

The data provided by Global Forest Resources Assessment 2020 (FRA 2020) says that in 2020 around 31% of Earth’s total land area was covered by forests, which is approximately 4.06 billion hectares. Forests account for around 3 million trees all around the world and are hence responsible for around 75% of the gross primary productivity of the biosphere and 80% of the total plant biomass of our planet. Thus, they hold a huge significance to the existence of life on earth.

Structure of a forest

Any forest ecosystem is stratified into the following layers

• The bottommost floor of the forest is covered with herbs, grasses, ferns, mushrooms and newly growing seedlings. It also consists of litter and detritus made up of dead and decaying leaves, animal wastes, etc. Decomposition of these dead decaying matter adds nutrients and humus to the soil and keeps it fertile.
• The next layer is the understory which consists of shrubs, bushes and young trees. The vegetation at this layer is adapted to survive under the shade of tall trees above them.
• The network of twigs, branches, and leaves of tall and mature trees form the canopy. The canopy consists of the crowns of the tall trees and is the most productive part of the forest as the crown receives maximum sunlight for photosynthesis. The lower layers of the forest receive shade and protection from the canopy.
• A few scattered, very tall trees that grow past the canopy forms the emergent layer.

Fig: Stratification in a fore

Types of Forests

Based on their latitudinal position, forests can be broadly classified into the following three types - tropical, temperate and boreal.

Tropical Forest

The forests lying between the latitudes 23.5 ˚S and 23.5 ^oN are considered as tropical forests. These are mostly seen in sub-Saharan Africa, Southeast Asia, and Central America. The temperature in these forests range between 20-35 ^oC and the annual rainfall is as high as 200-500 cm per year. These forests are very rich in flora and fauna biodiversity and house many endangered species of the world such as the Harpy eagle found in forests of South and Central America, Bonobos ape found in the tropical forests of Congo, etc. These forests are home to deer, forest goats, tapirs, antelopes, elephants, jaguars, leopards, snakes and lizards.

Tropical forests can further be categorised into evergreen rainforests, montane or cloud forests, tropical deciduous forests, tropical coniferous forests, tropical dry forests, tropical moist forests. The rainforests especially show a distinct stratification of layers due to an abundant variety of plants growing in these forests. The tall trees have leaves with drip tips to allow rainwater to drip and buttress roots are present for additional support to tall plants. Rosewood, ebony, mahogany, palms, bamboos are some of the common trees found in the forests of the tropical zone.

Fig: Tropical forests

Temperate Forest

The temperate forests stretch between latitudes 25^o to 50^o north and south of the Equator. These forests form the second largest biome in the world and cover almost 25% of Earth’s land area. Eastern North America and Eurasia house these forests. Temperate forests are classified as deciduous forests, coniferous forests, rainforests and mixed forests.

These latitudes experience four distinct seasons and hence temperatures keep varying throughout the year. Rainfall is abundant, keeping the soil moist and fertile and allowing a diverse range of flora to flourish. It includes broadleaved trees like maple, oak, etc and needle leaved trees like pine, cypress, etc can grow depending on the climate and type of temperate forest. The ground vegetation lacks grasses and is mostly covered in ferns and mosses. Herbs and shrubs are more common in evergreen coniferous forests. The top storey reaches 25-30 m in deciduous forests and around 30-35 m in coniferous forests.

The fauna is diverse too including bears, deer, squirrel, opossum, beaver, rabbit, elk, wolves, lizards, salamanders, snakes, lions, sparrows, owls, woodpeckers, etc.

Fig: Temperate forests

Boreal Forests

These forests are spread over the subarctic zones and are stretched between latitudes 50^o-60˚ North and South of the equator. These forests are also known as Taiga and are found in Scandinavia, Siberia, and North America (Alaska and Canada). Boreal forests form one of the largest biomes of the world. Being closer to the poles, the temperature in these forests is generally below freezing point of water. These forests experience longer winters and shorter summers. Annual precipitation is also less. Dominant plants are spruce, fir and pine and other conifers with needle leaves. Owing to the cold, mammals found in these forests have a thick furry coat. Siberian tigers, Asiatic and American black bears, brown bears, coyotes, Red foxes, mooses, deer, elks, etc are some common mammals. A wide variety of different reptiles and amphibians such as red-sided garter snake, blue-spotted salamander, Siberian salamander, wood frog, boreal chorus frog, American and Canadian toad, etc and fishes such as Alaska blackfish, lake whitefish, Arctic lamprey, etc are also found.

These forests serve as the nesting ground for around 300 species of birds in the summer, of which only 30 remain during the winter and others migrate to warmer countries. Eagles, ravens, buzzards, etc are commonly found.

Fig: Boreal forests

Importance of forests

Forests are known to harbour a large number of trees which perform photosynthesis and release fresh oxygen into the atmosphere while taking up carbon dioxide from the atmosphere.

The forest ecosystem is considered to be one of the most biodiversity rich ecosystems as it serves as a habitat for many plant, animal and microbial species. In the absence of excessive human intervention, the biotic (living) components of the forest ecosystems help to maintain the ecological balance.

The deep roots of the tall trees in a forest help to reduce soil erosion and also help in storing and collecting rainwater in the form of groundwater.

Forests provide us with the raw materials for the manufacture of processed end products such as paper, furniture, tissue, rubber etc. A large number of food items such as honey, cashew, fruits, and spices, are obtained from forests.

Forests serve as the source of livelihood for many tribes and nearby villagers who protect the biodiversity of the forests in return of the monetary gains they receive by selling forest-based items.

Many trees in the forests have medicinal value and chemicals extracted from them are used in pharmaceutical or cosmetic industries.

Forests help to maintain the water cycle by absorbing water from the soil through their leaves and then releasing the excess water as vapour through transpiration from the surface of their leaves. The release of water vapour into the atmosphere helps to bring about rainfall and cools the atmosphere.

Fig: Water cycle

Deforestation

Removal, decrease or deterioration of forested areas is called deforestation. Deforestation is not a modern practice, even the Mahabharata mentions the clearing of the Khandav forests for creating pastures. The importance of forests can be understood better when we take a look at how fast our forests are declining and the impact that this rapid decline is having on us.

In 1900 the total forested area of the world was around 7000 million hectares by 1975 it had been reduced to 2890 million hectares and by 2000 it was reduced to around 2500 million hectares. The decline has mainly affected the tropics when compared with the temperate forests. The rate of decline in the area covered by tropical forests is around 10 million hectares per year, which is an alarming rate and can completely wipe them off by the end of the century.

Fig: Deforestatio

But what causes this decline? The several factors contributing to deforestation are -

1. Forests were extensively exploited and denuded by early civilisations which were largely dependent on cattle, agriculture and extensive use of timber. Firewood was the only source of fuel.

Fig: Timber and firewood

2. With an increase in human population, forests were cleared to create space for human settlements.

Fig: Human settlements

3. Natural and anthropogenic (caused by humans) forest fires.

Fig: Forest fires

4. Jhuming or slash and burn agricultural practice of tribals in which they cut down and burn forest areas to create agricultural land.

Fig: Jhum cultivation

5. Quarrying and mining carried out in hilly and forested areas spoil the vegetation and cause deforestation.
6. Dams and reservoirs built for hydroelectric projects may submerge large areas of forest land.
7. Canals passing through forest areas kill many trees due to seepage of water.
8. In India over 300 million livestock graze in forests, causing a large-scale degradation of the herbs, shrubs and seedlings.

Fig: Overgrazin

9. The large-scale demand for wood cannot be met through the natural regeneration capacity of the forests. Thus, slow deforestation is going on everywhere.

Effects of deforestation

Shrinkage of fuel wood

Decrease of forest area has created scarcity of fuel wood which has created a pressure for using cow dung as a fuel in rural areas. Vegetation on the outskirts of villages and towns is destroyed. Fuelwood and litter are now being collected illegally from nearby forests.

Shrinkage of timber wood

Demand for timber wood is rising but the availability is low. The condition is so bad that in Assam, which used to be the home of forests, wood is procured from other states for manufacturing packing cases. A lot of timber wood in our country is now imported from other countries.

Changes in climate

Deforestation causes reduction in intensity and periodicity of rainfall. The summers become hotter and the winters colder. Lack of rainfall may lead to desertification (degradation of land resulting in dry, arid and infertile land) in dry areas.

Fig: Desertificatio

Sudden changes in climates and wind currents may lead to untimely cyclones and other natural disasters.

Global warming

Plant cover helps in absorbing CO₂ and releasing O₂ during photosynthesis. As plant cover is reduced during deforestation, less CO₂ is absorbed which leads to an increase in CO₂ concentration in the atmosphere. CO₂ is a greenhouse gas which contributes to trapping the heat radiated from the earth and keeping the earth warm, even at night. With increase in its concentration, more and more heat is trapped in the atmosphere, leading to an increase in the average temperature of the Earth and causing global warming.

Fig: Greenhouse gases

Soil erosion and flood

In the mountains, forests are essential for trapping and absorption of precipitation and storage of water. The trees in the forest help to slow down the speed of runoff water after precipitation and the water is released slowly. In the absence of forest cover, rain water is not retained in the sloped terrains of the hills and mountains and the fast flowing water erodes the topsoil. Every year in India, around 6000 million tonnes of topsoil is brought down from the hills by soil erosion.

Fig: Erosion of fertile topsoil leads to formation of arid patches of lan

Fast flowing water carrying silt also produces fast flowing rivulets during the rainy seasons. These cause flash floods in the plains. Every year around 400 million people are affected by floods in the Indian subcontinent.

The mud or silt carried by rivers during the rainy season is deposited in water reservoirs and river beds. As more and more mud is brought down due to increased soil erosion, the capacity of the water reservoirs decreases. Siltation also causes changes in water courses.

Drought

Due to decrease in annual rainfall, there is little water in the rain-fed rivers during the non-rainy seasons. Non availability of water ultimately leads to drought.

Loss of biodiversity

Deforestation causes habitat loss and extinctions of many plant, animal and microbial species.

Fig: Loss of biodiversity

Tribals

A number of tribals live in the forests where their culture, livelihood and physical survival are linked. Deforestation destroys their culture and livelihood.

Conservation of forests

Forest conservation is the protection, restoration and preservation of forest cover to ensure -

• Sustainable yield of forest products and services to people and industry both for the present and the future.
• Maintenance of long term ecological balance by preventing soil erosion, improving climate and providing perennial flow of water.

This can be achieved by two approaches - protection or conservation forestry and production or commercial forestry.

Protection or Conservation Forestry

It is a group of forestry practices that allow for recovery of degraded forests, protection of fragile forest ecosystems, increasing forest cover and controlling those uses which degrade forests. Some examples of such practices would be afforestation (creation of forest cover over bare area) and reforestation (development of forests in denuded regions), setting aside forest tracks as national parks and sanctuaries, selective graving, selective cutting of trees, etc.

Production or Commercial Forestry

It is the practice of raising useful trees, shrubs and other forest plants on selected tracts for fulfilling commercial requirements, without exploiting the natural forests.

Practice Problems

Q1. Which of the following correctly represents the geographical location of Temperate forests?

A. 25^o to 70^o North of Equator
B. Between 23.5 ˚S and 23.5 ^oN latitudes
C. Between latitudes 25^o to 50^o north and south of the Equator
D. Between latitudes 50^o-60˚ North and South of the equator

Solution: The temperate forests stretch between latitudes 25^o to 50^o north and south of the Equator. These forests form the second largest biome in the world and cover almost 25% of Earth’s land area. Eastern North America and Eurasia house these forests. Temperate forests are classified as deciduous forests, coniferous forests, rainforests and mixed forests.

Thus, the correct option is c.

Q2. Which of the following is an endangered species of the tropical forests?

A. Siberian tiger
B. Harpy eagle
C. Red fox
D. Arctic Lamprey

Solution: The tropical forests are very rich in flora and fauna biodiversity and house many endangered species of the world such as the Harpy eagle found in forests of South and Central America, Bonobos ape found in the tropical forests of Congo, etc.

The Siberian tigers, the Red foxes and Arctic lampreys are inhabitants of the boreal forests.

Thus, the correct option is b.

Q3. Deforestation might lead to

1. increased rainfall
2. reduction in the concentration of Greenhouse gases in the atmosphere
3. flash floods
4. Drought

A. I and III
B. I and II
C. II and III
D. III and IV

Solution: Forests are largely responsible for annual rainfall in an area as a large amount of water vapour is released into the atmosphere due to transpiration from the trees in the forest. This water vapour condenses and precipitates as rain. Deforestation leads to removal of forest cover and hence results in decreased rainfall. Due to reduction in rainfall, rain-fed rivers dry up and may lead to droughts and desertification of dry lands.

In the mountains, forests are essential for trapping and absorption of precipitation and storage of water. The trees in the forest help to slow down the speed of runoff water after precipitation and the water is released slowly. In the absence of forest cover, rain water is not retained in the sloped terrains of the hills and mountains and the fast flowing water erodes the topsoil. Fast flowing water carrying silt also produces fast flowing rivulets during the rainy seasons. These cause flash floods in the plains.

CO₂ is a greenhouse gas. Plant cover helps in absorbing CO₂ and releasing O₂ during photosynthesis. As plant cover is reduced during deforestation, less CO₂ is absorbed which leads to an increase in CO₂ concentration in the atmosphere.

Thus, the correct option is d.

Q4. State five ecological significance of forests.

Answer: Five ecological significance of forests are -

• Forests are known to harbour a large number of trees which perform photosynthesis and release fresh oxygen into the atmosphere while taking up carbon dioxide from the atmosphere. Thus they help in keeping the air fresh and help to maintain the balance of these gases in the atmosphere.
• The forest ecosystem is considered to be one of the most biodiversity rich ecosystems as it serves as a habitat for many plant, animal and microbial species. In the absence of excessive human intervention, the biotic (living) components of the forest ecosystems help to maintain the ecological balance.
• The deep roots of the tall trees in a forest help to reduce soil erosion and also help in storing and collecting rainwater in the form of groundwater.
• Forests serve as the source of livelihood for many tribes and nearby villagers who protect the biodiversity of the forests in return of the monetary gains they receive by selling forest-based items.
• Forests help to maintain the water cycle by absorbing water from the soil through their leaves and then releasing the excess water as vapour through transpiration from the surface of their leaves. The release of water vapour into the atmosphere helps to bring about rainfall and cools the atmosphere.

FAQs

Q1. What is silviculture?
Answer: Silviculture is the art and science of managing the growth, quality, structure, and health of forests to meet various values and needs such as habitat for wildlife, aesthetic beauty and production of timber.

Q2. What was the Chipko movement?
Answer: The chipko movement started in March, 1973 from Gopeshwar in Chamoli district of Tehri-Garhwal region of Uttarakhand to prevent felling of trees. The term ‘chipko’ refers to the practice of hugging the trees selected for cutting to prevent them from being cut down. Important leaders of this movement were Gaura Devi, Sunderlal Bahuguna and Chandi Prasad Bhatt.

Q3. In whose memory is the Amrita Devi Bishnoi Wildlife Protection Award instituted by the Government of India?
Answer: Forest conservation has been an old practice in India. In the fifteenth century, Guru Jambeshwar Maharaj enunciated 29 principles for protecting the environment and followers of his principles are known as Bishnois (bish -20, noi -9). Bishnois do not allow felling of trees and killing of animals. In 1731, the king of Jodhpur asked his ministers to arrange for wood for building a wooden castle. When his men reached a forest near the Khejarli village to cut down the Khejri trees (Prosopis cineraria), a bishnoi woman named Amrita Devi hugged the tree and challenged the king’s men to first kill her, before cutting the tree down. She sacrificed her life along with her daughters and 360 other bishnois to save the trees. The Government of India has instituted the Amrita Devi Bishnoi Wildlife Protection Award in her memory to commemorate rural individuals and communities who show exemplary courage and dedication for protecting wildlife.

Q4. What is agroforestry?
Answer: Agroforestry is a scheme created by the National Commission on Agriculture or NCA (1976), under production or commercial forestry, which involves plantation of multipurpose trees and shrubs, along with crops. It is helpful in removing soil defects, providing timber, fuel, and fodder to farmers.

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