EVS Unit-1 Ecosystem PDF

Unit-1 Ecosystem (03 hours) An ecosystem is a chain of interaction between organisms and their environment. The term “Ecosystem” was first coined by A.G.Tansley, an English botanist, in 1935. The ecosystem is the structural and functional unit of ec...

Unit-1 Ecosystem (03 hours) An ecosystem is a chain of interaction between organisms and their environment. The term “Ecosystem” was first coined by A.G.Tansley, an English botanist, in 1935. The ecosystem is the structural and functional unit of ecology where the living organisms interact with each other and the surrounding environment. Structure of the Ecosystem The structure of an ecosystem is characterized by the organization of both biotic and abiotic components. This includes the distribution of energy in our environment. It also includes the climatic conditions prevailing in that particular environment. The structure of an ecosystem can be split into two main components, namely:  Biotic Components or Living organisms  Abiotic Components or Non-living organisms The biotic and abiotic components are interrelated in an ecosystem. It is an open system where the energy and components can flow throughout the boundaries. Biotic Components or Living organisms Biotic components refer to all life in an ecosystem. Based on nutrition, biotic components can be categorized into  Autotrophs,  Heterotrophs  Saprotrophs (or decomposers).  Producers include all autotrophs such as plants. They are called autotrophs as they can produce food through the process of photosynthesis. Consequently, all other organisms higher up on the food chain rely on producers for food.  Consumers or heterotrophs are organisms that depend on other organisms for food. Consumers are further classified into primary consumers, secondary  Primary consumers are always herbivores (veg)that they rely on producers for food.  Secondary consumers depend on primary consumers for energy. They can either be a carnivore (non veg) or an omnivore (veg & non veg).  Tertiary consumers are organisms that depend on secondary consumers for food. Tertiary consumers can also be an omnivore.  Quaternary consumers are present in some food chains. These organisms prey (hunt) on tertiary consumers for energy. Furthermore, they are usually at the top of a food chain as they have no natural predators.  Decomposers include saprophytes such as fungi and bacteria. They directly thrive on the dead and decaying organic matter. Decomposers are essential for the ecosystem as they help in recycling nutrients to be reused by plants. Abiotic Components or Non-living organisms Abiotic components are the non-living component of an ecosystem. It includes air, water, soil, minerals, sunlight, temperature, nutrients, wind, altitude, turbidity, etc. An aquatic ecosystem is an ecosystem in a water. There are two types of aquatic ecosystem they are 1. Lentic ecosystem 2. Lotic ecosystem Lentic ecosystem The term lentic (from the Latin lentos, meaning slow or motionless), refers to standing waters such as lakes and ponds (lacustrine), or swamps and marshes (paludal), Lentic ecosystem has still waters Ex: ponds, Bain marshes ditches reservoirs, seeps, lakes. Lotic Ecosystem Lotic (from the Latin lotus, meaning washing), refers to running water (fluvial or fluviatile) habitats such as rivers and streams. Lotic ecosystem has flowing water Ex: creeks, Streams, runes reveres springs Brookes and channels. Terrestrial ecosystem A terrestrial ecosystem is a land-based community of organisms and the interactions of biotic and abiotic components in a given area. Examples of terrestrial ecosystems include the tundra, taigas, temperate deciduous forests, tropical rainforests, grasslands, and deserts.  Terrestrial ecosystems support most of our development, from raw materials to food production. Forests make up 30% of the Earth’s surface, provide oxygen and shelter for many land species, and constitute and important stock of carbon. Functions of Ecosystem The functions of the ecosystem are as follows: 1. It regulates the essential ecological processes, supports life systems and renders stability. 2. It is also responsible for the cycling of nutrients between biotic and abiotic components. 3. It maintains a balance among the various trophic levels in the ecosystem. 4. It cycles the minerals through the biosphere. 5. The abiotic components help in the synthesis of organic components that involves the exchange of energy. Questions 1. Define Ecosystem 2. Explain Structure Ecosystem 3. Define Biotic components, Give Example 4. Define Abiotic components Give example 5. Define Terrestrial Ecosystem with example. Global warming Global warming is the gradual and continuous increase in average temperature of surface of the earth, which in turn, causes climatic changes. Earth absorbs about 75% of the total solar energy reaching its surface thereby increasing its temperature. Some of this energy is radiated back in to the atmosphere. The gases present in the atmosphere for example ozone, methane. Carbon dioxide, water vapour and chlorofluorocarbons are called greenhouse gases, they absorb some heat there by restricting the heat to escape from atmosphere. These gases add to the heating of the atmosphere and result in global warming. Causes of Global Warming Following are the major causes of global warming: Man-made Causes of Global Warming Deforestation Plants are the main source of oxygen. They take in carbon dioxide and release oxygen thereby maintaining environmental balance. The forests are being depleted for many domestic and commercial purposes. This has led to an environmental imbalance, thereby giving rise to global warming. Use of Vehicles The use of vehicles even for a very short distance results into various gaseous emissions. Vehicles burn fossil fuels which emit a large amount of carbon dioxide and other toxins into the atmosphere resulting in a temperature increase. Chlorofluorocarbon With the excessive use of air conditioners and refrigerators, humans have been adding CFCs into the environment which affects the atmospheric ozone layer. The ozone layer protects the earth surface from the harmful ultraviolet rays emitted by the sun. The CFCs has led to ozone layer depletion making way for the ultraviolet rays, thereby increasing the temperature of the earth. Industrial Development With the advancement of industrialization, the temperature of the earth has been increasing rapidly. The harmful emissions from the factories add to the increasing temperature of the earth. Agriculture Various farming activities produce carbon dioxide and methane gas. These add to the greenhouse gases in the atmosphere and increase the temperature of the earth. Overpopulation Increase in population means more people breathing. This leads to an increase in the level of carbon dioxide. The primary gas causing global warming, in the atmosphere is carbon dioxide. Natural Causes of Global Warming Volcanoes Volcanoes are one of the largest natural contributors to global warming. The ash and smoke emitted during volcanic eruptions goes out into the atmosphere and affects the climate. Water Vapour Water vapour is a kind of greenhouse gas. Due to the increase in earth’s temperature more water gets evaporated from the water bodies and stays in the atmosphere adding to global warming. Melting Permafrost Permafrost is there where glaciers are present. It is a frozen soil that has environmental gases trapped in it for several years. As the permafrost melts, it releases the gases back into the atmosphere increasing the earth’s temperature. Forest Blazes Forest blazes or forest fires emit a large amount of carbon-containing smoke. These gases are released into the atmosphere and increase the earth’s temperature resulting in global warming. Effects of Global Warming Following are the major effects of global warming: Rise in Temperature Global warming has led to an incredible increase in earth’s temperature. Since 1880, the earth’s temperature has increased by ~1 degrees. This has resulted in an increase in the melting of glaciers, which have led to an increase in the sea level. This could have devastating effects on coastal regions.  Threats to the Ecosystem Global warming has affected the coral reefs that can lead to a loss of plant and animal lives. Increase in global temperatures has made the fragility of coral reefs even worse. Climate Change Global warming has led to a change in climatic conditions. There are droughts at some places and floods at some. This climatic imbalance is the result of global warming. Spread of Diseases Global warming leads to a change in the patterns of heat and humidity. This has led to the movement of mosquitoes that carry and spread diseases. High Mortality Rates Due to an increase in floods, tsunamis and other natural calamities, the average death toll usually increases. Also, such events can bring about the spread of diseases that can hamper human life. Loss of Natural Habitat A global shift in the climate leads to the loss of habitats of several plants and animals. In this case, the animals need to migrate from their natural habitat and many of them even become extinct. This is yet another major impact of global warming on biodiversity. Questions: 1. What is Global warming 2. What are the causes of the global warming? 3. Explain Effects of global warming. Greenhouse effect The Swedish scientist Svante Arrhenius was first brought this term in 1896. The greenhouse effect is a natural process that keeps the earth warm. It is caused by a layer of gases that traps heat energy from the sun. This layer of gasses is made up of water vapour, carbon dioxide, nitrous oxide, methane, chlorofluorocarbon, which are called the greenhouse gasses. Atmosphere contains carbon dioxide only in small quantities (0.03%). Yet it is very important constituent of atmosphere. Sunlight of different wavelength falls on the earth, some of it absorbed, and some portion is reflected in to space in the form of infrared radiation. Carbon dioxide molecules absorb these radiations and make atmosphere Warm. This heating caused by trapped radiation in the atmosphere by the blanket of greenhouse gases is called greenhouse effect The heating caused by trapped radiation in the atmosphere by the blanket of greenhouse gases is called greenhouse gasses. Ozone Depletion Ozone is a form of oxygen. Each molecule of ozone contains 3 atoms of oxygen. Its molecular formula is O3. Ozone get formed by combining the atoms of oxygen at Stratosphere. Ozone layer is a band of 15 Km to 35 Km from the surface of the earth. This layer is thickest at height of about 23 km. This ozone blanket absorbs a major part of the sun’s ultraviolet radiation and protect us from its harmful effects. Causes of Ozone Deflation. Deflation of ozone is caused by Chlorofluorocarbons. They are compounds containing the elements of carbon, fluorine and chlorine. Chlorofluorocarbons (CFC) are used in refrigerator system and any power generation system burns fuel and produces CO 2. It clears that the emission of CFCs in the atmosphere creates global warming because of greenhouse effect. When CFCs present in the atmosphere reaches the ozone layer, A chain of reaction takes place which initiate ozone layer depletion. It creates the holes, through which large amount of harmful heat in the form of ultraviolet rays falls on the earth and increases the earth temperature.  Ozone layer depletion is the gradual thinning of the earth’s ozone layer in the upper atmosphere caused due to the release of chemical compounds containing gaseous bromine or chlorine from industries or other human activities.” Effects of Ozone Layer Depletion The depletion of the ozone layer has harmful effects on the environment. Let us see the major effects of ozone layer depletion on man and environment. Effects on Human Health The humans will be directly exposed to the harmful ultraviolet radiations of the sun due to the depletion of the ozone layer. This might result in serious health issues among humans, such as skin diseases, cancer, sunburns, cataract, quick ageing and a weakened immune system. Effects on Animals Direct exposure to ultraviolet radiations leads to skin and eye cancer in animals. Effects on the Environment Strong ultraviolet rays may lead to minimal growth, flowering and photosynthesis in plants. The forests also have to bear the harmful effects of the ultraviolet rays. Effects on Marine Life Planktons are greatly affected by the exposure to harmful ultraviolet rays. These are higher in the aquatic food chain. If the planktons are destroyed, the organisms present in the lower food chain are also affected. Questions: 1. Define Greenhouse effect 2. What are the greenhouse gasses? 3. Define ozone Deflation, 4. What are the causes and Effects of greenhouse Gases? 5. What are the causes and Effects of Ozone depletion?