Environmental Studies PDF

# શ્રી સ્વામિનારાયણ ડિવાઇન મિશન ## Introduction * Environmental studies is a multidisciplinary field. * Environment means surroundings. * It is generally used as an abstract concept. * Surroundings may be natural, man-made, physical, chemical, or biotic. * The environment is a complex...

# શ્રી સ્વામિનારાયણ ડિવાઇન મિશન ## Introduction * Environmental studies is a multidisciplinary field. * Environment means surroundings. * It is generally used as an abstract concept. * Surroundings may be natural, man-made, physical, chemical, or biotic. * The environment is a complex of many things encompassing an organism that interacts not only with the organisms but also amongst themselves. * Environment studies deal with every issue that affects living beings on earth. * It is the study of interrelationships between living creatures and all aspects of their environment. * It essentially requires a multidisciplinary approach that brings about an appreciation of our natural world and the impact of humans on its integrity. ## What is Environmental Science? * Environmental science is an applied science that seeks practical answers to the increasingly important question of how to make human civilisation sustainable using the finite resources available on the earth. * It has long been held that environmental science deals with the study of the atmosphere, the land, the oceans, and the great chemical cycles that flow through physical and biological systems. * However, it is increasingly noticed that modern ES is becoming interdisciplinary, preparing people for global citizenship and training them to be flexible, competent to analyze and be a good decision-making. ## Branches of Environmental Science * The three branches of environmental science are Earth, life, and social. * The advancement in the knowledge of environment, explosive increases in human population, scarcity of place, food problems, degradation of hygienic conditions, threatening depletion of natural resources, and socioeconomic problems have caused the need for extensive and captive study of the environment, particularly in relation to human survival, and benefit. * This whole study of environment is known as **environmental biology**. ## Major Environmental Problems Major environmental problems can be divided into: 1. More population. 2. Pollution. 3. Depletion of Resources. 4. Global changes. 5. Wars. ## Forest Resources Forests are an important resource in two ways: 1. **Ecologically** 2. **Economically** ### Ecological Benefits of Forests 1. Forests help in balancing oxygen and carbon dioxide levels in the atmosphere by regulating earth's temperature and hydrological cycle. 2. Forests check the rain-bearing winds and cause rainfall. Further, they increase the amount of moisture in the atmosphere, thus preventing drought situations. 3. They minimize the extreme variations in climatic conditions and make the climate bearable. 4. They control floods during heavy rains by impeding the velocity of run-off soil surface, check soil erosion etc. 5. They act as windbreaks and protect the adjoining farmlands against strong winds. 6. They increase the fertility of soil. 7. They provide shelter to wild animals and birds. 8. They provide fresh air, beautiful scenery, and become recreational centres. ### Economic Benefits of Forests 1. They provide grass for feeding, timber for house building, ship building, furniture, etc. 2. They supply firewood and charcoal for homes and industries. 3. Forests provide raw materials for various forest-based industries. 4. Products like bamboo, resins, gums, medicine, etc. are obtained from forests. 5. They provide honey for food and medicines, bee-wax for candles. ## Over-Exploitation Of Forests * Rapid increase in population, industrialisation, and urbanisation has brought about indiscriminate felling of trees and denudation of forests. * The forest areas at global, regional, and local levels have so drastically decreased due to our exploitation that several serious environmental problems have been created. * Many of the developing countries of the tropical and sub-tropical regions have lost sustainable portions of their forests due to conversion of forest land into agricultural land to feed the millions. ## Deforestation * The temporary or permanent removal of forests covered from a forest land is known as deforestation. * The term deforestation refers to the destruction of indigenous forests and woodlands. It doesn't include the removal of industrial forests such as plantations. * It is one of the outcomes of various developmental activities. * Forest clearings were made not only for village settlements but also for cultivation. * As the population increased, more forests were cleared for various uses, and apart from this, the commercial exploitation of forests is the main cause of deforestation. * There was a time when 70% of the land area was covered with forests, and now the total forest covered has reduced to 16% only at a global level. ## Effects of Deforestation 1. Soil erosion. 2. Increase in the sediment loads of the rivers. 3. Siltation of reservoirs and riverbeds. 4. Increase in the frequency and dimension of floods and droughts. 5. Intensification of greenhouse effects. 6. Increase in the destructive force of the storms. 7. Economic loss due to damages of agricultural crops. 8. Decrease in the supply of raw materials and timber. 9. Marked decrease in fodder for animals. 10. Extinction of species 11. Alteration in the carbon and water cycles. 12. Social problems in the form of economic poverty, crimes, etc. ## Water Resources * Water is essential to all life. * Life originated in water. * Means of obtaining and conserving water have shaped the nature of terrestrial life. * It is essential not only for the sustenance of human life but also for the quality of life as well. * Water is the essence of life on earth and totally dominates the chemical composition of all organisms. * Various forms of water are found in every system and section of the ecosphere - atmosphere, lithosphere, and hydrosphere. * However, despite the enormous quantity of the substance that exists, only a small proportion of it is actually usable by human beings. * The ocean alone constitutes 97% of the hydrosphere and the frozen fields, ice caps and glaciers make up another 2% of the water-land. * In land surface water-land (lakes and rivers), a count for barely 0.02%. ## Surface Water Resources * As a rough estimate, the annual rainfall in India would be equivalent to about 3700 billion cubic metres of water. * Around 1250 cubic metres is lost by evapotranspiration and another 790 billion cubic metres by seepage into the soil. * Thus leaving 1660 cubic metres has surface flow into the rivers. * There are other 44 medium and 35 major rivers, which are mostly seasonal in nature. ## Ground Water Resources * It has been estimated that out of about 790 billion cubic metres of water that seeps into the soil, about 430 billion cubic metres remain in the top soil layers and produces soil moisture which is essential for growth of vegetation. * The remaining 360 billion cubic metres percolates into the porous strata and represents the actual enrichment of underground water. * Out of this water that can be extracted economically, only about 225 billion cubic metres. ## Concept of Ecosystem * Living organisms cannot live isolated from the non-living environment because they later provide the energy for their survival of the form. * That is there is an interaction between a biotic community and its environment to produce a stable system. * A natural self-sufficient unit which is known as an ecosystem. * Ecosystems are the parts of nature where living organisms interact amongst themselves and with their physical environment. * The term ecosystem was coined by Arthur Tansley, an English Botanist, in 1936. * An ecosystem is the structural and functional unit of ecology encompassing complex interaction between its biotic and abiotic components. ## Structure and Function of an Ecosystem * Each ecosystem has two main components: 1. Biotic 2. Abiotic. ### Biotic Component: * Living organisms including plants, animals, and microorganisms that are present in an ecosystem, form the biotic component. ### Food Chain: * Producers, primary consumers, secondary consumers, tertiary consumers. #### Producers: * The green plants have chlorophyll with the help of which they trap solar energy and change it into chemical energy of carbohydrates using simple inorganic compounds mainly H2O and CO2. This process is known as photosynthesis. * The green plants manufacture their own food. They are known as autotrophs. * The chemical energy stored by the producers is utilized partly by the producers for their own growth and survival, and the remaining is stored in the plant parts for their future use. #### Consumers: 1. **Primary Consumers:** First-order consumers or herbivores: These are the animals which feed on plants or the producers. They are called herbivores. * Examples: rabbit, deer, goat, cattle, etc. 2. **Secondary Consumers:** Second-order consumers or primary carnivores: The animals which feed on the herbivores are called the primary carnivores. * Examples: cats, foxes, snakes, etc. 3. **Tertiary Consumers:** Third-order consumers: These are the large carnivores which feed on the secondary consumers. * Example: wolves. 4. **Quaternary Consumers:** Fourth-order consumers or omnivores: These are the largest carnivores which feed on the tertiary consumers and are not eaten up by any other animals. * Examples: lions, tigers. ### Decomposers or Reducers: * Bacteria and fungi belong to this category. * They break down the dead organic materials of producers and consumers for their food and release to the environment the simple inorganic and organic substances produced as by-products of their metabolisms. * This simple substances are reused by the producers resulting in cycling exchange of materials between the biotic community and abiotic environment of the ecosystem. * The decomposers are known as saprotrophs.