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  1. 1. Ecology & Ecosystems Environmental Studies Unit-2
  2. 2. Ecology and Ecosystems  Ecology is the scientific study of relations that living organisms have with respect to each other and their natural environment.  Under ecology, we study various ecosystems which are a part of the biosphere.  An ecosystem includes all the organisms and the nonliving environment that are found in a particular place.
  3. 3. Ecological Succession 1
  4. 4. Ecological Succession  Ecological succession is the observed process of change in the species structure of an ecological community over time.  Ecological succession occurs when the conditions of an environment suddenly and drastically change. 2
  5. 5. Trophic Levels • A tropic level is the position occupied by an organism in a food chain. Trophic levels can be analyzed on an energy pyramid. • Producers are found at the base of the pyramid and compromise the first trophic level. • Primary consumers make up the second trophic level. • Secondary consumers make up the third trophic level. • Finally tertiary consumers make up the top trophic level. 3
  6. 6. Food Chain  A food chain shows the feeding relationship between different living things in a particular habitat.  Food chains show how energy is passed from the sun to producers, from producers to consumers, and from consumers to decomposers.  In any ecosystem, many food chains overlap. When this happens, the food chain forms a food web.
  7. 7. Grazing Food Chain The "grazing" food chain includes the producers and consumers that cycle energy from living plants. The "detritus" food chain cycles energy from non-living remains of both plants and animals (also called detritus). The "grazing" food chain has a number of steps that start with the producers, or the plants, and flows through a series of levels of consumers. At each step only about 10% of the energy is passed up through the chain. The rest is passed back into the atmosphere as heat through breathing and decomposition. 4
  8. 8. In the first step plants convert the sun’s energy to chemical energy through a process called photosynthesis. The chemical energy is stored both as food and as structural elements in the plant. The next step involves the primary consumers, animals that eat only plants. At step three are the secondary consumers, also called predators; these animals eat primary consumers. At step four are the tertiary consumers that eat secondary consumers, and sometimes primary consumers as well
  9. 9. Detritus food chain The "detritus" food chain cycles energy from non- living remains of both plants and animals (also called detritus). The "detritus" food chain is a system where the energy produced by the breakdown of dead plant and animal matter is cycled into the "grazing" food chain. Detritus is organic matter formed by decaying animal or plant tissue, or fecal matter. Detritus eaters (or detritivores) such as insects, worms and other small organisms feed on dead plants, waste products from animals and dead animals. Decomposers are fungal or bacterial organisms that work within the dead material to help break it down, activating decay and decomposition. This important part of the ecosystem takes the last of the energy that was originally absorbed by the plants and returns it to the soil. 5
  10. 10. Characteristics of Detritus Food Chain a)Primary source of energy is dead organic matter called 'detritus' which are fallen leaves, plant parts or dead animal bodies. b) Primary consumers are 'detritivores' including protozoans, bacteria, fungi, etc which feed upon the detritus saprophytically. c) Detritivores are in turn eaten by secondary consumers such as insect larvae, nematodes, etc. d) Detritus food chains are generally shorter than grazing food chains e) In nature, detritus food chains are vital as the dead organic matter of grazing food chain is acted upon by the detritivores to recycle the inorganic elements into the ecosystem.
  12. 12. Food Web  Food Webs are Food Chains that intersect each other. Food webs are what really happens in nature.  A predator from one food chain may be linked to the prey of another food chain  Several food chains linked together 7
  13. 13. Ecological pyramids
  14. 14. An ecological pyramid is a graphical representation designed to show…….  the number of organisms,  energy relationships, and  biomass of an ecosystem. They are also called Eltonian pyramids after Charles Elton, who developed the concept of ecological pyramids. Charles Elton (1927) developed the concept of ecological pyramids who noted that "…the animals at the base of a food chain are relatively abundant while those at the end are relatively few in number…" 8
  15. 15. Producer organisms (usually green plants) form the base of the pyramid, With succeeding levels above representing the different trophic levels (respective position of the organisms within ecological food chains). Succeeding levels in the pyramid represent the dependence of the organisms at a given level on the organisms at lower level.
  16. 16. There are three types of pyramids: of numbers, of biomass, and of energy. 9
  17. 17. Pyramid of Biomass  Biomass is (is the mass of living biological organisms in a given area or ecosystem at a given time) renewable organic (living) material.  A pyramid of biomass is a representation of the amount of energy contained in biomass, at different trophic levels for a particular time.  It is measured in grams per meter2, or calories per meter2. This demonstrates the amount of matter lost between trophic levels.  Each level is dependent on its lower level for energy, hence the lower level determines how much energy will be available to the upper level. Also, energy is lost in transfer so the amount of energy is less higher up the pyramid.
  18. 18.  There are two types of biomass pyramids: upright and inverted.  An upright pyramid is one where the combined weight of producers is larger than the combined weight of consumers. An example is a forest ecosystem.  An inverted pyramid is one where the combined weight of producers is smaller than the combined weight of consumers. An example is an aquatic ecosystem.
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  20. 20. Pyramid of Numbers  The pyramid of numbers represents the number of organisms in each trophic level. This pyramid consists of a plot of relationships between the number herbivores (primary consumers), first level carnivore (secondary consumers), second level carnivore (tertiary consumers) and so forth. This shape varies from ecosystem to ecosystem because the number of organisms at each level is variable  Upright, partly upright and inverted are the three types of pyramids of numbers.  An aquatic ecosystem is an example of upright pyramid where the number of organisms becomes fewer and fewer higher up in the pyramid.  A forest ecosystem is an example of a partially upright pyramid, as fewer producers support more primary consumers, but there are less secondary and tertiary consumers.  An inverted pyramid of numbers is one where the number of organisms depending on the lower levels grows closer toward the apex. A parasitic food chain is an example.
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  23. 23. Pyramid of Energy The pyramid of energy represents the total amount of energy consumed by each trophic level. An energy pyramid is always upright as the total amount of energy available for utilization in the layers above is less than the energy available in the lower levels. This happens because during energy transfer from lower to higher levels, some energy is always lost.
  24. 24. Ecosystem 13
  25. 25. Functions of Natural Ecosystem Air pollution are tapped by leaves of tree and convert into harmless compounds Waste water gets filtrated through the natural soil and make drinkable
  26. 26. Types Of Ecosystems Forest Ecosystem Grassland Ecosystem Desert Ecosystem Aquatic Ecosystem Estuarine Ecosystem
  27. 27. Forest Ecosystem  A forest ecosystem is a terrestrial unit of living organisms.  All interacting among themselves and with the environment (soil, climate, water and light) in which they live. 14
  28. 28. Types Of Forest Ecosystems Tropical Rain Forest ( Average rain fall: <150cm/year) Temp: 18oC Warmed , humid, high diversity of animal, plant, insects Tropical Deciduous Forest (Rain fall: 100-120cm/yr) Climate is not evenly distributed
  29. 29. Temperate Deciduous (cold climate, annual temp: 7-15oC) Summer is very hot and winter is very cold Tall decidous tree Boreal Forest/TIAGA/CONIFEROUS Climate is very cold Rainfall: 100mm to 350 mm Temperate Rain forest Very cold Winter rain fall Summer is very hot and Dry
  30. 30. Functions Forest Ecosystems Enhance the water resources in both quality and quantity  Hydrological cycle depend on the forest ecosystem Forest gives shelter to wildlife and fish Considered as a pathway for exchange and regulation of atmospheric gases, water and trace elements
  31. 31. Coniferous forest of Alaska Tropical rain forest Deciduous Forest 15
  32. 32. Grassland Ecosystem Grasslands are areas where the vegetation is dominated by grasses
  33. 33. Types Of Grassland Ecosystem Tropical and Savannas grasslands  Tropical and subtropical grasslands, savannas, and shrublands are a grassland terrestrial biome located in semi-arid to semi- humid climate regions of subtropical and tropical latitudes. Tropical grasslands include the savanna usually associated with Africa, and savanna-type grasslands found in India, Australia, Nepal and the Americas. 16
  34. 34.  Temperate grasslands  Temperature: warm to hot season (often with a cold to freezing season in winter)  Soil: fertile with rich nutrients and minerals  Plants: grass; trees or shrubs in savanna and shrubland  Animals: large, grazing mammals; birds; reptiles  Rain fall: 25-60cm/yr  Although large areas have now been converted to agriculture, in the past temperate grasslands were home to herds of large grazing animals such as bison, deer or kangaroos.  North America, the steppes of Russia and the pampas of Argentina. 17
  35. 35. Flooded Grass land  Flooded grasslands and savannas is a terrestrial biome.  Its component ecoregions are generally located at subtropical and tropical latitudes, which are flooded seasonally or year-round.  A common term is swamp. Characteristics Flooded grasslands are characterized by:  very wet to saturated soil moisture content in nutrient rich soils.  in temperate—warm to tropical—hot climates.  They are found as grasslands, savannas, and wetlands. 18
  36. 36. Tundra Biome Tundra is the coldest of all the biomes. Tundra comes from the Spanish word tunturia, meaning treeless plain. It is noted for its frost-molded landscapes, extremely low temperatures, little precipitation, poor nutrients, and short growing seasons. The two major nutrients are nitrogen and phosphorus. Nitrogen is created by biological fixation, and phosphorus is created by precipitation. Tundra is separated into two types: arctic tundra and alpine tundra. characteristics Extremely cold climate Low biotic diversity Simple vegetation structure Short season of growth and reproduction Energy and nutrients in the form of dead organic material 19
  37. 37. Arctic Arctic tundra is located in the northern hemisphere, encircling the north pole and extending south to the coniferous forests of the taiga. The arctic is known for its cold, desert-like conditions. The growing season ranges from 50 to 60 days. The average winter temperature is -34° C (-30° F), but the average summer temperature is 3-12° C (37-54° F) which enables this biome to sustain life. Rainfall may vary in different regions of the arctic. Yearly precipitation, including melting snow, is 15 to 25 cm (6 to 10 inches). Soil is formed slowly. Alpine Alpine tundra is located on mountains throughout the world at high altitude where trees cannot grow. The growing season is approximately 180 days Mammals: pikas, marmots, mountain goats, sheep, elk Birds: grouselike birds Insects: springtails, beetles, grasshoppers, butterflies
  38. 38. Montane High-altitude grasslands located on high mountain ranges around the world, like the Páramo of the Andes Mountains. They are part of the montane grasslands and shrublands biome and also constitute tundra. Desert and xeric Also called desert grasslands, this is composed of sparse grassland ecoregions located in the deserts and xeric shrublands biome 20
  39. 39. Desert Ecosystem  A desert ecosystem exists where there is little rainfall and the climate is extreme in harshness.  It occupies about 17% of the earth’s surface. 21
  40. 40. Types Of Desert Ecosystem Temperate Deserts: Sahara in Africa, Thar in Rajasthan Tropical Deserts: Mojave in south California Cold Deserts: Gobi desert in China
  41. 41. Components of desert Ecosystem A biotic components: Nutrition's present in the soil and aerial environment Biotic Components: Producers: There are shrubs, Grasses and few trees. Some time few cacti Consumers: Reptiles, Insects, Birds mammals and camels Decomposers: There are very few, as due to poor vegetation the amount of dead organic matter is less. There are few fungi and most of them are thermophlic
  42. 42. Thar Desert Sahara Desert Mojave in south California Gobi desert in China 22
  43. 43. Aquatic Ecosystem  It is an ecosystem located in a water bodies.  The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems. 23
  44. 44. Types Of Aquatic Ecosystem Freshwater Ecosystem 1. Pond ecosystem 2. Lake ecosystem 3. Stream 4. Riverine Ecosystem 5. Fresh water marshes ecosystem
  45. 45. On the basis of water flow, fresh water ecosystem classified into two - Lentic ecosystem (Standing water bodies) - Lotic ecosystem (Running or flowing water bodies)
  46. 46. LOTIC ECOSYSTEMS  Lotic ecosystem may be perennial or seasonal  Perennials occasionally subjected to floods which cause damage to the surrounding areas  Lotic series distinguished by continued flow of water in one direction  Lotic systems are richer in oxygen and nutrients than lentic systems Egs:Spring,Stream or river ecosystems
  47. 47. LENTIC ECOSYSTEM  It may be perennial or seasonal  Oxygen content in the surface water to a depth of 3- 5 meters is enough to support life  In deeper levels oxygen is less and biological activities decreases  In bottom levels anaerobic conditions prevail and organisms that can thrive under such conditions are found at this depth  Egs: Lake,Pond,Swamp,Reservoirs etc
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  49. 49. POND ECOSYSTEM It is a simplest fresh water aquatic ecosystem It is a small body of standing shallow water It may receive enough water during rainy season It is a self sufficient & self regulatory ecosystem
  50. 50. Life span of small seasonal ponds ranges from a few weeks or months Life span of larger ponds are several hundred years Pond water contain a mixture of living organisms, both plants & animals, and inorganic and organic components.
  51. 51. LAKE ECOSYSTEM Big and natural fresh water bodies with standing water Functions like a giant permanent pond Lakes are formed when precipitation run-off or ground water seepage fills up depressions in the land formed by geological changes.
  52. 52. ZONATION A large lake has four zones(depending on the depth).They are: - LITTORAL: upper zone ,shallow water near the shore of lake. -LIMNETIC: open water away from the shore of lake. -PROFOUNDAL:deep water,too dark,not found plants or algae. -BENTHIC: bottom of the lake. 25
  53. 53. Types of Lake Artificial lake: Due to construction Obligotrophic lake: Low nutrition concentration Masotrphic: Moderate Nutrition Eutrophic: More amount of Nutrition : Dal Lake Dystrophic lake: Brown water with low pH and humic acid Desert salt lake: High concentration of Salts: Sambhar lake Rajasthan Volcanic lake: It occures by volcano: Japan Meromictic lake : Rich in salt
  54. 54. RIVER AND STREAM ECOSYSTEM They are flowing fresh water bodies. Flowing water follows distinct “channels”. Small channels – STREAMS Large channels – RIVERS Plants and animals live in streams and rivers depend upon the movement and speed of the water.
  55. 55. FRESHWATER MARSHES ECOSYSTEM It tend to be naturally fertile ecosystem. It is valuable in maintaining water tables in adjacent ecosystems. Periodic fluctuations in water levels resulting from seasonal and annual rainfall variation often accomplishes tidal like actions in terms of maintaining long range stability and fertility.
  56. 56. Marine Ecosystem 70% world cover by the water and 97% of this water is available in oceans and Seas. They play key role in survival of 2,50,000 species Oceans are major sinks of CO2 and play important role in Carbon cycle, Hydrological cycle Major ocean: Pacific, Atlantic, Indian, Arctic Pacific: Largest and cover 1/3 part of Earth
  57. 57.  Coastal Zone: Relatively warmer, Nutrition rich shallow water with sunlight and high production  Open Sea: Deeper part of ocean and away from submerged part of Continent is called continental shelf.  Euphotic zone: Received Enough light  Bathyal Zone: Dim light  Abyssal Zone: 1.5 to 5 km deep dark zone. No solar energy 26
  58. 58. Components of marine ecosystem Abiotic Components: Salt concentration in open sea is usually 3.5 % while dominant ions are sodium, chloride, sulpher magnasium and calcium Biotic components: Producers: phytoplanktons : macro and micro algae, cynobacteria Consumers: Herbivorous and Carnivores and top carnivorous Decomposers: Bacteria and fungi
  59. 59. Biogeochemical CyclesBiogeochemical Cycles
  60. 60. Biogeochemical Cycles describe the flow of essential elementsessential elements from the environment through living organisms and back into the environment. The biogeochemical cycle is the continuous flow of elements and compounds between organisms and the earth
  61. 61. Types of cycles Hydrological cycle: deal with the interchange of water with organisms and environment Gaseous cycle: Deal with inter change with gases Sedimentary cycle: Deals with SO4 and PO4 cycle and concern with the interchange of nutrition and minerals
  62. 62. Elemental Cycles H, O, and C make up > 99 % of the Earth’s biomass N, Ca, K, Mg, S, and P are significant nutrients Cycling of C, O, N, P, and S are discussed in this chapter
  63. 63. Concepts in Biogeo. Cycles  Reservoir - where material or mass is stored  Flux: rate of flow of material  Steady state: inflow = outflow  Dynamic state: fluxes are reservoirs are changing with time  Residence time: length of time a chemical stays in a reservoir  Feedback: positive and negative
  64. 64. Hydrological cycle 1. Reservoir – oceans, air (as water vapor), groundwater, lakes and glaciers; evaporation, wind and precipitation (rain) move water from oceans to land. 2. Assimilation – plants absorb water from the ground, animals drink water or eat other organisms which are composed mostly of water. 3. Release – plants transpire, animals breathe and expel liquid wastes.
  65. 65. Steps Evaporation and transpiration Condensation and formation of cloud: Rising air current all the vapour up into the atmosphere cool  formation of cloud cloud is made up of droplet of water Precipitation: Snow or rain fall Run off and collection of under ground water Infiltration and percolation
  66. 66. Hydrological Cycle 27
  67. 67. Human Impact Pollution of water Reduces the vegetation cover increases the surface ran off decreases the percolation Global warming Heavy deforestation reduces the transpiration loss of water through plants and trees
  68. 68. Carbon cycle Earth atmosphere contains 0.03% of CO2 CO2 is the basic source of carbon and constitutes of all organic material It found in caves ands mines and also evolves from volcanoes
  69. 69. Reservoirs of Carbon Carbon is found in all four spheres Biosphere - organic matter Atmosphere - CO2, CH4 Hydrosphere - H2CO3 ,HCO3 - , CO3 = Lithosphere - CaCO3 , coal, oil, and gas Processes: photosynthesis, formation of sediments, weathering, combustion, plate tectonics Decay of organic material
  70. 70. Carbon CycleCarbon Cycle (carbon is required for building organic compounds) 1. Reservoir – atmosphere (as CO2), fossil fuels (oil, coal), durable organic materials (for example: cellulose). 2. Assimilation – plants use CO2 in photosynthesis; animals consume plants. 3. Release – plants and animals release CO2 through respiration and decomposition; CO2 is released as wood and fossil fuels are burned.
  71. 71. Carbon Cycle 28
  72. 72. Human Interference Human-induced processes Extraction and combustion of fossil fuels (speeds up the medium-term cycling) Cement manufacturing Deforestation (biomass burning) All of these processes release CO2 into the atmosphere and affect the natural cycling of carbon
  73. 73. Nitrogen cycle Nitrogen is an essential constituent of animals and plants. Green plant combined with Nitrogen and carbohydrates to make proteins and Nucleic acid 78 % Not directly used most form of life Taken by Process called nitrogen fixation
  74. 74. Nitrogen CycleNitrogen Cycle (Nitrogen is required for the manufacture of amino acids and nucleic acids) 1. Reservoir – atmosphere (as N2); soil (as NH4 + or ammonium, NH3 or ammonia, N02 - or nitrite, N03 - or nitrate
  75. 75. Nitrogen CycleNitrogen Cycle 2. Assimilation – plants absorb nitrogen as either NH4 + or as N03 - , animals obtain nitrogen by eating plants and other animals. The stages in the assimilation of nitrogen are as follows:
  76. 76. Steps Nitrogen fixation Ammonification Nitrification and Denitrification
  77. 77. Nitrogen fixation Nitrogen Fixation: N2 to NH4 + by nitrogen-fixing bacteria (prokaryotes in the soil and root nodules), N2 to N03 - by lightning and UV radiation. 1. Biological : Nitrogen fixing bacteria 2. Industrial fixation: fertilizer 3. Electrification( N2 + O2-- Nitrogen Oxide Amonification: Amino acid and urea- Ammonia
  78. 78. Nitrification: 1. Nitrogen fixation Combination of Nitrogen with other element 2. Ammonification Organic Nitrogen- NH3 3. Nitrification and denitrification Ammonia(NH3)- ----- Nitrite forming bacteria(Nitromonas)----- Nitrite(NO2) Nitrite(NO2)--------Nitrobacter--------------- Nitrate Nitrate(NO3)--------Denitrification(Pseudomonas)--- Nitrogen
  79. 79. Nitrogen CycleNitrogen Cycle 3. Release – Denitrifying bacteria convert N03 - back to N2 (denitrification); detrivorous bacteria convert organic compounds back to NH4 + (ammonification); animals excrete NH4 + (or NH3) urea, or uric acid.
  80. 80. Nitrogen Cycle 29
  81. 81. 30
  82. 82. Human Impact Harvesting of timber Automobile and industrial exhaust Acid rain is caused by emissions of sulfur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids. NO2 + OH· → HNO3 Eutrophication
  83. 83. Oxygen Cycle Essential for aerobic life Closely linked to carbon cycle Very large reservoir (21% of gas in atm.), not susceptible to human interference Also, not a greenhouse gas Reservoirs: atmosphere, surface organic material (biosphere), and buried organic matter (lithosphere)
  84. 84. Oxygen Cycle Processes Photosynthesis/ respiration: short-term cycle; balanced on land; excess O2 in ocean -phytoplanktons Mineral oxidation, weathering, burial - removes O2 from atmosphere Combustion or weathering of organic matter - removes O2 from atmosphere Atmosphere => marine biota => sediments => rocks => atmosphere (fig )
  85. 85. Oxygen Cycle 31
  86. 86. Phosphorus Cycle 32
  87. 87. Phosphorus CyclePhosphorus Cycle (Phosphorus is required for the manufacture of ATP and all nucleic acids) 1. Reservoir – erosion transfers phosphorus to water and soil; sediments and rocks that accumulate on ocean floors return to the surface as a result of uplifting by geological processes 2. Assimilation – plants absorb inorganic PO4 3- (phosphate)from soils; animals obtain organic phosphorus when they plants and other animals 3. Release – plants and animals release phosphorus when they decompose; animals excrete phosphorus in their waste products
  88. 88. Phosphorus CyclePhosphorus Cycle 1. Reservoir – erosion transfers phosphorus to water and soil; sediments and rocks that accumulate on ocean floors return to the surface as a result of uplifting by geological processes 2. Assimilation – plants absorb inorganic PO4 3- (phosphate)from soils; animals obtain organic phosphorus when they plants and other animals 3. Release – plants and animals release phosphorus when they decompose; animals excrete phosphorus in their waste products 33
  89. 89. Biogeochemical cycles of other minerals, such as calcium and magnesium, are similar to the phosphorus cycle.
  90. 90. References/Sources 1. WsdPCrPGpOOsCS1f79kJCCu2IcRa4rgIFVyMYv0ed0xKM 2. 3. 4. 5. 6. 7. 8. 9. 10.
  91. 91. 11. 12. 13. 14. 15. 16. 17. 18. 19.
  92. 92. 20. 21. 22. 23. nh8yHrJ2_6_RZtmVKEVit0dj18K6Y=s88 24. RZ1Tmcj9dYgpbdlhcwiWehNedm3InWx9QZcwGDpsgwWsuYurFk=s109 25. ptNJ8_yaKIA-spRAX_F495qkBWplH-9eSs=s131 26. NjcKShsdk-NwwgAgJKasC5rr_P4Q=s119 27. D0N1EdCpelLhO9oFsf-DYWJQR40=s112 28. WjZANZ1OOJmn0E5gOtfwD7l7CWeD-yIHlBg96spbSIEn5YDzsyyw=s85
  93. 93. 29. srEW_1NH1AHfa1h2zMPut6dsAcOAa9oym44=s129 30. 2VHMa6LBlyVE70wbTHbJfXUtHHVY4=s85 31. V1e258isYr_RAQYQJl5EsXObaHa3xA=s85 32. SxFJd74wYMrXQ_qfQuphz3Vv0zciYKQQLXyhhxidsFybgBTb9lo97Tm27UTO 6HQ=s97 33. jLNzt9wE_RNXsLPraJtHPm32kDS1U=s97
  94. 94. Book/Web Resources • Environment & Ecology by Dr Gourkrishna Dasmohapatra