UPSC Geography Ecology and Ecosystem Biodiversity NCERT Extracts - Environment and Biodiversity

Natural Environment

• The place, people, things and nature that surround any living organism is called environment.
• It is a combination of natural and human made phenomena. While the natural environment refers to both biotic and abiotic conditions existing on the earth, human environment reveals the activities, creations and interactions among human beings.
• Land, water, air, plants and animals comprise the natural environment.
• Lithosphere is the solid crust or the hard top layer of the earth. It is made up of rocks and minerals and covered by a thin layer of soil.
• It is an irregular surface with various landforms such as mountains, plateaus, plains, valleys, etc. Landforms are found over the continents and also on the ocean floors.
• Lithosphere is the domain that provides us forests, grasslands for grazing, land for agriculture and human settlements. It is also a source of mineral wealth.
• The domain of water is referred to as hydrosphere. It comprises various sources of water and different types of water bodies like rivers, lakes, seas, oceans, etc. It is essential for all living organisms.
• The atmosphere is the thin layer of air that surrounds the earth. The gravitational force of the earth holds the atmosphere around it. It protects us from the harmful rays and scorching heat of the sun.
• It consists of a number of gases, dust and water vapour. The changes in the atmosphere produce changes in the weather and climate.
• Plant and animal kingdom together make biosphere or the living world. It is a narrow zone of the earth where land, water and air interact with each other to support life.

Ecosystem

• It is a system formed by the interaction of all living organisms with each other and with the physical and chemical factors of the environment in which they live, all linked by transfer of energy and material.
• All plants, animals and human beings depend on their immediate surroundings. Often they are also interdependent on each other. This relation between the living organisms, as well as the relation between the organisms and their surroundings form an ecosystem.
• There could be an ecosystem of large rain forest, grassland, desert, mountains, lake, river, ocean and even a small pond.

Human Environment

• Human beings interact with the environment and modify it according to their need. Early humans adapted themselves to the natural surroundings. They led a simple life and fulfilled their requirements from the nature around them.
• With time needs grew and became more varied. Humans learn new ways to use and change environment. They learn to grow crops, domesticate animals and lead a settled life.
• The wheel was invented, surplus food was produced, barter system emerged, trade started and commerce developed.
• Industrial revolution enabled large scale production. Transportation became faster. Information revolution made communication easier and speedy across the world.
• Have you ever thought why you love eating a juicy watermelon in summer and hot roasted peanuts in winter? A perfect balance is necessary between the natural and human environment. Humans must learn to live and use their environment in a harmonious way.

Some Principles of Sustainable Development

• Resect and care for all forms of life
• Improve the quality of human life
• Conserve the earth's vitality and diversity
• Minimise the depletion of natural resources
• Change personal attitude and practices toward the environment
• Enable communities to care for their own environment.

Resources and Development

• All the minerals, water resources, forests, wildlife, land within the political boundaries and oceanic area upto 12 nautical miles (22.2 km) from the coast termed as territorial water and resources therein belong to the nation.
• 1 There are international institutions which regulate some resources.          
• The oceanic resources beyond 200 nautical miles of the Exclusive Economic Zone belong to open ocean and no individual country can utilise these without the concurrence of international institutions.

Rio de Janeiro Earth Summit

• In June, 1992, more than 100 heads of states met in Rio de Janeiro in Brazil, for the first International Earth Summit. The Summit was convened for addressing urgent problems of environmental protection and socioeconomic development at the global level.
• The assembled leaders signed the Declaration on Global Climatic Change and Biological Diversity. The Rio Convention endorsed the global Forest Principles and adopted Agenda 21 for achieving Sustainable Development in the 21st century.

Agenda 21

• It is the declaration signed by world leaders in 1992 at the United Nations Conference on Environment and Development (UNCED), which took place at Rio de Janeiro, Brazil.
• It aims at achieving global sustainable development. It is an agenda to combat environmental damage, poverty, disease through global co-operation on common interests, mutual needs and shared responsibilities.
• At the international level, the Club of Rome advocated resource conservation for the first time in a more systematic way in 1968.
• Subsequently, in 1974, Gandhian philosophy was once again presented by Schumacher in his book Small is Beautiful.
• The seminal contribution with respect to resource conservation at the global level was made by the Brundtland Commission Report, 1987.
• This report introduced the concept of 'Sustainable Development' and advocated it as a means for resource conservation, which was subsequently published in a book entitled Our Common Future.
• Another significant contribution was made at the Earth Summit at Rio de Janeiro, Brazil in 1992.

Biodiversity

• Biodiversity is a system in constant evolution, from a view point of species, as well as from view point of an individual organism.
• The average half-life of a species is estimated at between one and four million years, and 99 per cent of the species that have ever lived on the earth are today extinct.
• Biodiversity is not found evenly on the earth.
• It is consistently richer in the tropics.
• As one approaches the polar regions, one finds larger and larger populations of fewer and fewer species.
• Biodiversity itself is a combination of two words, Bio (life) and diversity (variety).
• In simple terms, biodiversity is the number and variety of organisms found within a specified geographic region.
• It refers to the varieties of plants, animals and micro-organisms, the genes they contain and the ecosystems they form.
• It relates to the variability among living organisms on the earth, including the variability within and between the species and that within and between the ecosystems.
• Biodiversity is our living wealth. It is a result of hundreds of millions of years of evolutionary history.
• Biodiversity can be discussed at three levels: Genetic diversity; Species diversity and Ecosystem diversity.

Genetic Diversity

• Genes are the basic building blocks of various life forms.
• Genetic biodiversity refers to the variation of genes within species.
• Groups of individual organisms having certain similarities in their physical characteristics are called species.
• Human beings genetically belong to the homo sapiens group and also differ in their characteristics such as height, colour, physical appearance, etc., considerably. This is due to genetic diversity.
• This genetic diversity is essential for a healthy breeding of population of species.

Species Diversity

• This refers to the variety of species. It relates to the number of species in a defined area.
• The diversity of species can be measured through its richness, abundance and types.
• Some areas are more rich in species than others. Areas rich in species diversity are called hotspots of diversity.

Ecosystem Diversity

• The broad differences between ecosystem types and the diversity of habitats and ecological processes occurring within each ecosystem type constitute the ecosystem diversity.
• The 'boundaries' of communities (associations of species) and ecosystems are not very rigidly defined. Thus, the demarcation of ecosystem boundaries is difficult and complex.
• Biodiversity has contributed in many ways to the development of human culture and, in turn, human communities have played a major role in shaping the diversity of nature at the genetic, species and ecological levels.
• Biodiversity plays the following roles: ecological, economic and scientific.

Ecological Role of Biodiversity

• Species of many kinds perform some function or the other in an ecosystem.
• Nothing in an ecosystem evolves and sustains without any reason.
• That means, every organism, besides extracting its needs, also contributes something of useful to other organisms.                                
• Can you think of the way we, humans contribute to the sustenance of ecosystems.
• Species capture and store energy, produce and decompose organic materials, help to cycle water and nutrients throughout the ecosystem, fix atmospheric gases and help regulate the climate.
• These functions are important for ecosystem function and human survival.
• The more diverse an ecosystem, better are the chances for the species to survive through adversities and attacks, and consequently, is more productive.
• Hence, the loss of species would decrease the ability of the system to maintain itself.
• Just like a species with a high genetic diversity, an ecosystem with high biodiversity may have a greater chance of adapting to environmental change.
• In other words, the more the variety of species in an ecosystem, the more stable the ecosystem is likely to be.

Economic Role of Biodiversity

• For all humans, biodiversity is an important resource in their day-to-day life.
• One important part of biodiversity is 'crop diversity', which is also called agro- biodiversity.
• Biodiversity is seen as a reservoir of resources to be drawn upon for the manufacture of food, pharmaceutical, and cosmetic products.
• This concept of biological resources is responsible for the deterioration of biodiversity.
• At the same time, it is also the origin of new conflicts dealing with rules of division and appropriation of natural resources.
• Some of the important economic commodities that biodiversity supplies to humankind are: food crops, livestock, forests, fish, medicinal resources, etc.

Scientific Role of Biodiversity

• Biodiversity is important because each species can give us some clue as to how life evolved and will continue to evolve.
• Biodiversity also helps in understanding how life functions and the role of each species in sustaining ecosystems of which we are also a species.
• This fact must be drawn upon every one of us so that we live and let other species also live their lives. It is our ethical responsibility to consider that each and every species along with us have an intrinsic right to exist.
• Hence, it is morally wrong to voluntarily cause the extinction of any species.
• The level of biodiversity is, a good indicator of the state of our relationships with other living species.
• In fact, the concept of biodiversity is an integral part of many human cultures.

Loss of Biodiversity

• Since the last few decades, growth in human population has increased the rate I consumption of natural resources.
• It has accelerated the loss of species and habitation in different parts of the world.
• Tropical regions which occupy only about one-fourth of the total area of the world contain about three fourth of the world human population.
• Over exploitation of resources and deforestation have become rampant to fulfil the needs of large population.
• As these tropical rain forests contain 50 per cent of the species on the earth, destruction of natural habitats have proved disastrous for the entire biosphere.
• Natural calamities such as earthquakes, floods, volcanic eruptions, forest fires, drought etc. cause damage to the flora and fauna of the earth, bringing change the biodiversity of respective affected regions.
• Pesticides and other pollutants such as hydrocarbons and toxic heavy metals destroy the weak and sensitive species.
• Species which are not the natural inhabitants of the local habitat but are introduced in the system, are called exotic species.
• There are many examples when a natural biotic community of the ecosystem suffered extensive damage because of the introduction of exotic species.
• During the last few decades, some animals like tigers, elephants, rhinoceros, crocodile minks and birds were hunted mercilessly by poachers for their horn, tusks, hides, etc
• It has resulted in the rendering of certain types of organisms as endangered category.
• The International Union of Conservation of Nature and Natural Resources (IUCN) has classified the threatened species of plants and animals into three categories for the purpose of their conservation

Endangered Species

• It includes those species which are in danger of extinction. The IUCN publishes information about endangered species world-wide as the Red List of threatened species.

Vulnerable Species

• This includes the species which are likely to be in danger of extinction in near future if the factors threatening to their extinction continue.
• Survival of these species is not assured as their population has reduced greatly.

Rare Species

• Population of these species is very small in the world; they are confined to limited areas or thinly scattered over a wider area.

Conservation of Biodiversity

• Biodiversity is important for human existence. All forms of life are so closely interlinked that disturbance in one gives rise to imbalance in the others.
• If species of plants and animals become endangered, they cause degradation in the environment, which may threaten human being's own existence.
• There is an urgent need to educate people to adopt environment-friendly practices and reorient their activities in such a way that our development is harmonious with other life forms and is sustainable.
• There is an increasing consciousness of the fact that such conservation with sustainable use is possible only with the involvement and cooperation of local communities and individuals,                                
• For this, the development of institutional structures at local levels is necessary.
• The critical problem is not merely the conservation of species nor the habitat but the continuation of process of conservation.
• The Government of India along with 155 other nations have signed the Convention of Biodiversity at the Earth Summit held at Rio de Janeiro, Brazil in June, 1992.
• The world conservation strategy has suggested the following steps for biodiversity conservation:
• Efforts should be made to preserve the species that are endangered.
• Prevention of extinction requires proper planning and management.
• Varieties of food crops, forage plants, timber trees, livestock; animals and their wild relatives should be preserved;
• Each country should identify habitats of wild relatives and ensure their protection.
• Habitats where species feed, breed, rest and nurse their young should be safeguarded and protected.                               
• International trade in wild plants and animals be regulated.
• To protect, preserve and propagate the variety of species within natural boundaries, the Government of India passed the Wild Life (Protection) Act, 1972, under which national parks and sanctuaries were established and biosphere reserves declared.
• There are some countries which are situated in the tropical region; they possess a large number of the world's species diversity. They are called mega diversity centres.
• There are 12 such countries, namely Mexico, Columbia, Ecuador, Peru, Brazil, Democratic Republic of Congo, Madagascar, China, India, Malaysia, Indonesia and Australia in which these centres are located.
• In order to concentrate resources on those areas that are most vulnerable, the International Union for the Conservation of Nature and Natural Resources (IUCN) has identified certain areas as biodiversity hotspots.
• Hotspots are defined according to their vegetation. Plants are important because these determine the primary productivity of an ecosystem.
• Most, but not all, of the hotspots rely on species-rich ecosystems for food, firewood, cropland, and income from timber.
• In Madagascar, for example, about 85 per cent of the plants and animals are found nowhere else in the world.
• Other hotspots in wealthy countries are facing different types of pressures.
• The islands of Hawaii have many unique plants and animals that are threatened by introduced species and land development.

Some Important Facts

• Biotic: The world of living organisms, e.g. plants and animals.
• Abiotic: The world of non-living elements, e.g. land.
• On 5 June every year the World Environment Day is celebrated.
• Barter System: It is a trade in which goods are exchanged without the use of money.