Picture a herd of yaks grazing on a high meadow below the snow, and a rhododendron (lali gurans) tree in bright red flower on a cool hillside. Now picture the hot, flat Terai, with its sal forests, its rice fields and its rhinos. Would you ever see a yak in the Terai? Would a rhododendron grow there?
Everything around a living thing, the air, water, soil, light, heat, and the other plants and animals, is its environment. Different places have different environments, so different plants and animals live in them. Nepal climbs from about 60 m above sea level in the Terai to 8,849 m at the top of Sagarmatha in only about 200 km, so it has hot, mild, cold and frozen environments packed close together. That is why so many kinds of living things are found here.
The presence of many different kinds of plants, animals and other living things in a place is called biodiversity (bio = life, diversity = variety). Biodiversity and the environment are closely linked: the environment decides what can live in a place, and the living things in turn change their environment (forests make the air moist and hold the soil; earthworms make the soil loose and rich).
What does biodiversity mean?
Pick an answer to see why.
4.1 Natural resources
4.1.1 What natural resources are
Think about your morning. You woke up in a house made of bricks (from soil), wood (from a forest) or stone. You drank water from a tap or a spring. You ate rice and dal grown in the soil, cooked on a fire of firewood or on gas that came out of the ground. All of these came from nature.
Anything we get from nature that is useful to living things is a natural resource. Water, air, soil, sunlight, rocks and the minerals in them, forests, wild plants and animals, coal, petroleum and natural gas are all natural resources. We use them as food, as fuel (coal, firewood, petroleum), and as the raw materials from which industries make things: timber for furniture, cotton for cloth, iron ore for steel, limestone for cement. Without natural resources, people and other animals could not survive, farm or run industries. They are nature’s gift to living things.
Which of these is not a natural resource?
Pick an answer to see why.
4.1.2 Classification of natural resources
Natural resources can be sorted (classified) in more than one way.
By where they come from:
- Living (biotic) resources come from living things: forests, crops, wild plants and animals, fish, livestock.
- Non-living (abiotic) resources come from non-living things: air, water, soil, rocks, minerals.
By whether they can be replaced:
- Renewable natural resources are replaced by nature again and again, as fast as we normally use them, so they don’t run out: air, water, sunlight, forest products and soil. Rain refills the rivers every year; a cut tree’s place can be taken by a new one.
- Non-renewable natural resources exist only in a limited amount and take millions of years to form, so once used up they can’t be replaced in a human lifetime: coal, petroleum, natural gas, metals and rocks. Much of the world’s coal formed from forests that grew about 300 million years ago.
Why are coal and petroleum called non-renewable?
Pick an answer to see why.
4.1.3 Importance of water resources, water reserves and wetlands
Water is found in many places and many forms in nature: rain, snow and ice, rivers, lakes, ponds, springs and water underground. These are called water resources. There are two main kinds:
- Surface water: water on top of the ground, in rivers, streams, lakes, ponds and wetlands.
- Groundwater (underground water): rainwater that has soaked down into the soil and rocks. It comes up in springs, wells and tube wells.
Water reserves
A water reserve is a place where water from rain and from streams collects and is stored, forming a big store of water. Ponds, lakes and reservoirs (artificial lakes behind a dam) are water reserves. They come in all sizes, from a village pond to a lake several kilometers across. Some of Nepal’s main water reserves are Rara Lake (Mugu), Gosaikunda (Rasuwa), Ghodaghodi Lake (Kailali), Bishazari Lake (Chitwan) and Jagadishpur Reservoir (Kapilvastu), which was built for irrigation in the 1970s; and our many rivers carry and store water too.
The whole area of land from which rain flows into one river or lake is called its watershed (or catchment). Keeping a watershed under forest keeps its river or lake full of clean water.
Wetlands
A wetland is land that is soaked with water, or covered by shallow water, for all or much of the year: marshes and swamps (simsar), shallow lakes and their muddy, reedy edges. Water stays there all through the year, and the land around it stays wet and marshy, so special plants (reeds, water lilies, tall grasses) and animals live there. Koshi Tappu, on the Sapta Koshi river in the eastern Terai, is Nepal’s best-known wetland.
Wetlands and water reserves are very important for keeping nature in balance:
- The plants and animals found in them (fish, snails, water chestnut, lotus roots) are food for people and for other animals.
- They are the habitat (home) of many plants and animals. Fish, frogs and other water animals breed in their shallow water.
- Many birds migrate (travel) to them for part of the year, to escape very cold or very hot seasons elsewhere and to breed.
- They store rainwater and give water for drinking, irrigation, fishing and other uses. By soaking up flood water, they also protect the villages and fields downstream.
- They keep the temperature of the area even, and they help to run the water cycle (evaporation, clouds and rain) and refill the groundwater.
Which of these is the best description of a wetland?
Pick an answer to see why.
How does a wetland next to a river reduce flood damage downstream?
Pick an answer to see why.
4.2 Depletion of natural resources
The using up of natural resources faster than they can be replaced, or their destruction, is called depletion of natural resources.
As the number of people grows, so does the use of metals, petroleum, natural gas, timber and water. Forests are cut faster than they grow back. Every year, forest fires, most of them started by people and some by lightning, fill the air with smoke, burn crops and destroy the homes of wildlife; fires and deforestation together are reducing biodiversity. To grow more crops on less land, some farmers use chemical fertilizers and pesticides without control, and in time the soil loses its fertility. Growing industries release wastes that pollute the air, water and soil, so people can’t get fresh air to breathe. Paving over land and pumping too much water lower the level of the groundwater. Natural events destroy resources too: a volcanic eruption burns forests, and floods and landslides wash away soil.
The main causes of depletion of natural resources are:
- Overpopulation and unbalanced migration: more people need more food, water, fuel, land and houses; when many people move to one area (the Kathmandu Valley, the Terai towns), its resources are overused while villages are left empty.
- Unmanaged agriculture: too much chemical fertilizer and pesticide, burning crop waste, and farming on steep slopes without terraces.
- Deforestation and forest fires.
- Overconsumption: using far more than we need, and wasting it.
- Pollution of air, water and soil.
- Industrial and technical development, when it takes resources without care for the future.
- Natural disasters: floods, landslides, droughts, earthquakes.
Which of these would help a community forest to last for ever?
Pick an answer to see why.
4.3 Management of solid waste
Every home, farm and factory throws things away. From our houses come fruit and vegetable peels, leftover food, dust, paper, plastic bags and bottles. From industries come solid scraps, harmful gases and chemicals. From farms come straw, husks and stalks after the harvest. All these unwanted things are called waste or garbage. If waste is not managed properly, it causes pollution that can seriously harm us and other living things, and it spoils the balance of the environment.
Waste can be solid, liquid or gas. It can also be sorted in another way:
- Biodegradable waste is broken down (rotted) by bacteria and fungi into harmless substances that go back into the soil: peels, leftover food, leaves, paper, cotton cloth, cow dung.
- Non-biodegradable waste is not broken down by living things, or only over hundreds of years: plastic, glass, metal cans, batteries, polythene bags.
Different kinds of waste must be managed in different ways. When waste is managed properly, the environment stays clean, healthy and balanced; when it isn’t, it pollutes the soil and water too. Today, managing waste has become one of the biggest problems for city governments in Nepal and in many countries. The Kathmandu Valley alone produces well over 1,000 tonnes of waste every day, and more than half of it is kitchen waste that could have become compost.
Which of these wastes is non-biodegradable?
Pick an answer to see why.
The 3R model
Proper management of solid waste does more than solve the waste problem. It gives industries raw materials, saves natural resources, and can even earn money. One of the best ways of managing solid waste is the 3R model:
A. Reduction (reduce)
B. Reuse
C. Recycle
A. Reduction
Reduction means using natural resources and things wisely and less, so that less waste is made and less pollution is caused. For example:
- Take a reusable cloth or jute bag (jhola) to the market instead of taking a new polythene bag each time. If fewer polythene bags are used, fewer will be made, and there will be less to throw away.
- Don’t bring home unnecessary packaging: buy loose rice and lentils instead of small packets.
- Use fewer chemical fertilizers and pesticides: use organic manure (compost, dung) instead of chemical fertilizers, and biological methods to control pests (birds, frogs and helpful insects that eat them) instead of harmful insecticides.
- Write on both sides of the paper; repair things instead of buying new ones.
B. Reuse
Reuse means using a thing again, for the same or another purpose, instead of throwing it away. When the same thing is used again, fewer new things need to be bought, so fewer are made, and the harm to the environment is less. For example:
- One strong shopping bag can be used again and again.
- Clothes that no longer fit you can be given to someone who will wear them.
- Tins, plastic jars and glass bottles of powdered milk, chocolates and other products can store grain, flour, tea leaves, sugar and salt. Bigger containers can be used as flower pots.
- Plastic bags from rice and flour, and milk packets, can be made into pots for seedlings.
- Plastic and glass bottles can decorate a terrace, a porch or a garden.
C. Recycle
Recycling means using old, used things as the raw material for making new things. For example:
- Old newspapers, books and exercise books are pulped in paper mills to make new paper.
- Old pots and tools of iron, copper, brass and aluminium, and old wires, vehicles and machines, are melted to make new metal pots and articles.
- Old plastic bags, pipes, buckets and containers are melted by heating and remolded into new plastic articles.
That is why the scrap collector (kawadi) buys your old newspapers, bottles and tins: they are raw materials. Every recycled aluminium can saves about 95 % of the energy needed to make a new one from ore.
The 3R model is therefore very useful for managing solid waste.
Melting old plastic pipes to mold new buckets is an example of
Pick an answer to see why.
Exercise
1. Choose the correct option
a. Which one is a non-renewable natural resource?
Pick an answer to see why.
b. How does natural imbalance occur?
Pick an answer to see why.
c. How can we reduce the loss of life and property on the banks of rivers?
Pick an answer to see why.
d. What kind of solid waste management is remolding used plastics?
Pick an answer to see why.
e. What do water resources, water reserves and wetlands all have in common?
Pick an answer to see why.
f. Which statement defines biodiversity?
Pick an answer to see why.
2. Fill in the blanks
Use these words: environment, balanced environment, recycle, renewable, non-renewable, biodiversity, reduction. (Three words are not needed.)
The presence of a variety of animals and plants is ……… .
Answer
biodiversity
The maintenance of balance in the amounts of living beings and non-living things is called a ……… .
Answer
balanced environment
The practice of not bringing home the packaging of things we buy is called ……… .
Answer
reduction
A natural resource that is replaced soon after it is used up in a place is called a ……… resource.
Answer
renewable. (The words environment, recycle and non-renewable are not used.)
3. Answer the following questions
Write the importance of biodiversity.
Answer
- It gives us food (grains, fruit, vegetables, fish, meat, milk), medicines (many medicines come from plants such as timur, chiraito and yarsagumba), firewood, timber, fibers and fodder.
- Each living thing is a link in a food chain; with many kinds of living things, the balance of nature is kept: plants make food and oxygen, animals eat them, decomposers return the nutrients to the soil.
- Forests and grasslands protect the soil, store water and keep the air clean and the climate mild.
- Insects such as bees pollinate crops and fruit trees.
- Wild relatives of crops (wild rice, wild fruit) help scientists breed new crops that resist disease and drought.
- National parks, birds and wildlife bring tourists, which gives people jobs and income.
- Many plants and animals are part of our culture and religion (tulsi, pipal, the cow, the national bird danphe).
How can we keep an ecosystem balanced?
Answer
An ecosystem stays balanced when the amounts of its living things and non-living things stay steady. We can help by:
- not cutting forests faster than they grow back, and planting trees;
- protecting wild animals and their habitats; not hunting or poaching;
- not polluting air, water and soil; managing waste with the 3Rs;
- using natural resources wisely, and only as much as we need;
- conserving wetlands, water sources and soil;
- using organic manure and biological pest control instead of too many chemicals;
- preventing forest fires.
What is a wetland?
Answer
A wetland is land that is soaked with water, or covered by shallow water, for all or much of the year, with marshy ground around it, such as a marsh, a swamp or the shallow edge of a lake. Koshi Tappu, Ghodaghodi and Bishazari are wetlands of Nepal.
Why are water reserves important?
Answer
- They store rainwater, giving water for drinking, irrigation, fishing and electricity all year.
- They are the habitat of fish and many other plants and animals, and a stopping place for migratory birds.
- They give food: fish, snails, lotus and water chestnut.
- They refill the groundwater, so springs and wells don’t dry up.
- They hold back flood water and keep the local temperature even.
- Lakes such as Rara and Gosaikunda attract tourists and pilgrims.
Mention the major methods of solid waste management.
Answer
The main method is the 3R model:
- Reduce: use less and make less waste (cloth bags, no unnecessary packaging).
- Reuse: use things again (jars for storage, bottles as pots, old clothes given away).
- Recycle: make new things from old ones (paper from waste paper, new pots from melted metal, new articles from melted plastic).
Besides these, biodegradable waste can be made into compost or biogas, and what is left can be buried safely in a sanitary landfill. Separating waste at home into biodegradable and non-biodegradable makes all these methods easier.
How does using a lot of chemical fertilizers and insecticides, to grow more crops on less land, deplete natural resources?
Answer
- Too much chemical fertilizer makes the soil hard and acidic and kills earthworms and the useful bacteria in it, so in time the soil loses its fertility.
- Rain washes the extra fertilizer and insecticide into rivers, ponds and wells, polluting the water and killing fish and other water life.
- Insecticides kill not only pests but also useful insects such as bees (which pollinate crops), and the birds and frogs that eat the poisoned insects, reducing biodiversity.
- The poisons can stay on vegetables and fruit and harm the people who eat them.
Explain the importance of wetlands.
Answer
- The plants and animals of wetlands (fish, snails, lotus, water chestnut) are food for people and animals.
- Wetlands are the habitat of many plants and animals; fish, frogs and other water animals breed in them.
- Migratory birds come to them in the cold or hot season, to rest, feed and breed.
- They store rainwater and give water for many uses, and refill the groundwater.
- They soak up flood water like a sponge, protecting life and property downstream.
- They keep the local temperature even and help the water cycle.
- They trap mud and dirt and clean the water flowing through them.
“Nepal is rich in biodiversity.” Justify the statement.
Answer
- Nepal rises from about 60 m in the Terai to 8,849 m at Sagarmatha within about 200 km, so it has every kind of climate, from tropical to cold and frozen, close together.
- Each climate zone has its own plants and animals: sal forests, rhinos and tigers in the Terai; oak and rhododendron forests and red pandas in the hills; yaks, blue sheep and snow leopards in the Himalaya.
- With good rainfall and many kinds of soil, rivers, lakes and wetlands, there are habitats for many more kinds of living things.
- So although Nepal covers only about 0.1 % of the world’s land, it has more than 6,000 kinds of flowering plants and nearly 900 kinds of birds (about one in twelve of the world’s bird species), and some living things (such as the spiny babbler) are found nowhere else.
Write the differences between:
- i.reuse and recycle
- ii.a water reserve and a wetland
- iii.renewable and non-renewable resources
Answer
(i)
| Reuse | Recycle |
|---|---|
| A thing is used again as it is. | A thing is broken down, melted or pulped to make a new thing. |
| It needs no factory and almost no energy. | It is done in a factory and needs energy. |
| e.g. a jam jar used to store salt | e.g. old paper made into new paper |
(ii)
| Water reserve | Wetland |
|---|---|
| A place where water collects and is stored in a large body. | Land soaked with or covered by shallow water for much of the year. |
| The water can be deep (a lake, a reservoir). | The water is shallow, with marshy ground around it. |
| e.g. Rara Lake, Gosaikunda | e.g. Koshi Tappu, Ghodaghodi |
(iii)
| Renewable resource | Non-renewable resource |
|---|---|
| Replaced by nature again and again. | Limited in amount; not replaced in a human lifetime. |
| Doesn’t run out if used wisely. | Runs out with continuous use. |
| e.g. air, water, soil, forests | e.g. coal, petroleum, metals, rocks |
Explain the relationship between the environment and biodiversity.
Answer
The environment decides which living things can live in a place: its temperature, rainfall, soil and height suit some plants and animals and not others. So different environments have different living things, and a country with many environments, like Nepal, has great biodiversity.
In turn, living things shape their environment: forests keep the air moist (which helps bring rain), shade the ground and hold the soil; earthworms and decomposers make soil fertile; plants give out oxygen. When biodiversity is lost (forests cut, animals killed), the environment is damaged too: landslides, dry springs, polluted air. When the environment is damaged (pollution, fires), biodiversity is lost. Each depends on the other.
What precautions should be taken while using natural resources?
Answer
- Use them only as much as needed; don’t waste them (close taps, switch off lights).
- Use renewable resources no faster than nature replaces them: plant a tree for each one cut.
- Use non-renewable resources such as petroleum and metals carefully, and reuse and recycle them.
- Don’t pollute air, water and soil while using them.
- Prefer renewable energy: hydropower, solar, biogas.
- Protect forests from fire, and wildlife from hunting.
- Think of future generations: they need the same resources.
What are natural resources? On what bases are they classified?
Answer
Everything found in nature that is useful to living things is a natural resource, e.g. water, air, soil, forests, minerals, coal and petroleum.
They are classified:
- by their origin: living (biotic) resources such as forests and animals, and non-living (abiotic) resources such as air, water, soil and minerals;
- by whether they can be replaced: renewable resources such as air, water, soil and forests, and non-renewable resources such as coal, petroleum, metals and rocks.
Describe any five causes of depletion of natural resources in short.
Answer
- Overpopulation: more people need more food, water, land, fuel and houses, so forests are cleared and resources overused.
- Unmanaged agriculture: too much chemical fertilizer and pesticide ruins the soil and pollutes the water; farming steep slopes without terraces washes soil away.
- Deforestation and forest fires: forests are lost faster than they grow back, with their wildlife, soil and springs.
- Pollution: wastes from homes, vehicles and industries make air, water and soil unfit to use.
- Natural disasters: floods, landslides, droughts and earthquakes destroy forests, farmland and water sources.
Others: overconsumption, unplanned industrial and technical development, unbalanced migration.
4. Look at the photo and answer the questions
What is the impact of this activity on agriculture?
Answer
Without trees to hold it, the fertile top soil is washed away by rain onto the fields below or into the rivers, so the fields get less fertile. Landslides and floods damage farmland. Springs that water the fields dry up. Farmers also lose fodder, leaf litter for compost, and the birds and insects that eat crop pests and pollinate crops.
What are its effects on water resources and water reserves?
Answer
Rain runs off the bare ground quickly instead of soaking in, so groundwater is not refilled and springs and wells dry up in the dry season, while floods get worse in the monsoon. The water carries mud into rivers, ponds and lakes, making them muddy and filling them up with silt.
How does the activity affect wildlife?
Answer
The animals and birds lose their habitat: their homes, shelter, nesting places and food. Many die or have to move away; some come into villages and fields looking for food. Fewer kinds survive, so biodiversity falls.
Which natural resources are shown in the photo?
Answer
Forest (trees and timber), soil, and the air and sunlight around them; the forest is also the home of wildlife.
What could you do to restore the balance?
Answer
Plant trees and look after the saplings; join or support a community forest group; use wood and paper wisely and recycle paper; use alternatives to firewood (biogas, improved stoves, electricity); help protect forests from fire; and tell others why forests matter.
Practice every question in the book, and keep track of the ones you miss →