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A slideshow on the meaning, types and components of an Ecosystem.
- 1. ECOSYSTEMS ENVIRONMENTAL SCIENCE KAMALA NEHRUCOLLEGE ANURAG CHAUHDARY
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- 3. ECOLOGY “ Scientific studyof the relationship of living organisms with each other and with their environment “ Ecology deals with the study of organisms in their natural home interacting with their surroundings. Oikos = Home; logos = study Coined by = Ernst Haeckel, 1869 Father of modern ecology = Eugene P. Odum
- 4. ECOSYSTEM An ecosystemis a community of different species interacting with one another and with their nonliving environment of soil, water, other forms of matter, and energy, mostly from the sun. An ecosystem is a self-regulating group of biotic communities of species interacting with one another and with their non-living environment exchanging energy and matter. Ecosystem show large variations in their size, structure, composition etc. however, all ecosystems are characterized by certain basic structural and functional features which are common to all.
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- 6. CHARACTERISTICS OF ANECOSYSTEM Natural or Artificial Variable in size No clear boundary Not isolated from each other Matter and Energy move from one ecosystem to another Concept given by A. G. Tansley, 1935 STRUCTURAL AND FUNCTIONAL UNIT OF BIOSPHERE
- 7. 1. STRUCTURE OFECOSYSTEM The nature of a ecosystem depends on : Geographical features of the region Climatic conditions Soil and water characteristics Communities of plants, animals, microbes to live in specific conditions An ecosystem structure includes both biological (biotic) and non-living (abiotic) components. ABIOTIC COMPONENTS BIOTIC COMPONENTS
- 8. 1.i. ABIOTIC COMPONENTS Allphysical and chemical components i.e. the NON LIVING COMPONENTS The physical and chemical components of an ecosystem constitute its abiotic structure SOLAR ENERGY WATER AIR SOIL CLIMATIC FACTOR NUTRIENTS MOST IMPORTANT determinants of where and how well an organism exist in its environment
- 9. ABIOTIC COMPONENTS RANGEOF TOLERANCE : It is the stretch in an ecosystem where all the necessary abiotic factors are in optimum level for population growth
- 10. ABIOTIC COMPONENTS LIMITING FACTORPRINCIPLE “ Too much or too little of any abiotic factor can limit or prevent growth of a population, even if all other factors are at or near the optimal range of tolerance ” LIEBIG’s LAW OF MINIMUM
- 11. ABIOTIC COMPONENTS The limitingabiotic factors : Sunlight/Energy Solar flux and duration of solar radiation Average temperature Geographical position Rainfall and water availability Substratum/Soil Salinity of water Dissolved gases in water Essential nutrients viz. C, N, P, K, H, O, S etc.
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- 13. 1.ii. BIOTIC COMPONENTS All living beings in the ecosystem i.e. plants, animals , microbes, etc. All the biotic components of an ecosystem are influenced by the abiotic components and vice versa, and they are linked together through energy flow and nutrient cycling. They are classified into: a) Primary producers b) Consumers c) Decomposers
- 14. 1.ii.a. Primary Producers Autotrophs or self-feeders Make their own food directly from the environment by the process of photosynthesis or chemosynthesis. (Sunlight, Water, Carbon Dioxide, inorganic compounds, etc.) Can utilize only 1% of solar energy Green plants, Aquatic green plants and algae, Phytoplankton, specialized bacteria
- 15. Primary Producers Photosyntheticorganisms by the process of PHOTOSYNTHESIS Chemosynthetic organisms convert simple inorganic compounds from their environment into more complex nutrient compounds without using sunlight by the process of CHEMOSYNTHESIS. E.g. Specialized bacteria in and around hydrothermal vents. Green plants, algae, etc. having chlorophyll pigment.
- 16. 1.ii.b. Consumers Heterotrophsor other feeders or PHAGOTROPHS Can’t produce their own food directly from the environment, feeds on other organisms to obtain their nutrients There are several types of consumers: Primary consumers Secondary consumers Tertiary consumers and so on…
- 17. Consumers Primary consumers:plant eaters or herbivores. E.g. Cows, Goats, Zooplanktons, etc. Secondary consumers: meat eaters or carnivores. E.g. Hyenas, Frogs, Zooplankton eating fishes, etc. Tertiary consumers: High level carnivores. E.g. Tigers, Wolves, Sharks, etc. Omnivores: Feed on both plants and animals. E.g. Human, Cockroaches, Fox, Pigs, etc.
- 18. 1.ii.c. Decomposers SAPROTROPHSor OSMOTROPHS: feeds upon and breaks down and decompose dead organic plant or animal matter. They can be: Detritivores: feeds on dead matter of plants and animals. E.g. Butterflies, Beetles, Termites, earthworms, etc. Saprophytes: decompose dead organic waste to simpler inorganic forms by the help of enzymes which can again used by the autotrophs. E.g. Fungi, Bacteria, Microorganisms, etc.
- 20. 2. FUNCTIONS OFECOSYSTEM i. Energy Flow through food chain/food web. (Physical function) ii. Nutrient Cycling (Biogeochemical cycle) iii. Productivity iv. Homeostasis or feedback control mechanisms. v. Ecological succession or Ecological development. Food chain, Food Web, Ecological Pyramids.
- 21. 2.i. ENERGY FLOW Force for all metabolic activities. Energy Flow is from producer to top consumer. It flows from all trophic levels and is always from lower trophic level to higher trophic level. Energy flow is always unidirectional. Loss of energy at each trophic level in the form of unusable heat i.e. it decreases from the first trophic level upwards. (Only 10% of energy moves to higher trophic levels – LINDEMAN’S LAW). The percentage of usable chemical energy transferred as biomass from one trophic level to the next is called ecological efficiency.
- 22. ENERGY FLOW Thereare 3 ways to assess the energy flow in an ecosystem: a) Food Chain b) Food Web c) Ecological Pyramids
- 23. 2.i.a. FOOD CHAIN Organisms in the ecosystem are related to each other through feeding mechanism. A sequence of organisms that feed on one another, form a food chain. “Transfer of food energy from green plants (producers) through a series of organisms with repeated eating and being eaten is called a food chain” Grasses → Grasshopper → Frog → Snake → Hawk/Eagle The number of trophic levels are limited in any food chain.
- 24. The producersand consumers are arranged in the ecosystem in a definite manner and their interaction along with population size are expressed together as trophic structure. Each food level/step is known as trophic level. The amount of living matter at each trophic level at a given time is known as standing crop or standing biomass. FOOD CHAIN
- 25. FOOD CHAIN Twotypes (as per the source of energy for the 1st consumer): GRAZING FOOD CHAIN The consumers which start the food chain utilizing plant as their food. It begins from green plants and the primary consumer is herbivore. DETRITUS FOOD CHAIN The consumers which start the food chain utilizing dead organic matter as their food. It begins from the dead organic matter to the detrivore organisms which in turn make food for protozoan to carnivores. It helps in nutrient cycling.
- 26. Grazing food chainv/s Detritus food chain
- 27. Grazing food chainv/s Detritus food chain These two chains are not isolated but rather are linked with each other
- 28. 2.i.b. FOOD WEB Trophic levels in an ecosystem are not linear rather they are interconnected and make a food web. “ A food web illustrates all possible transfers of energy and nutrients among the organisms in an ecosystem.” Provides alternative pathways for transfer of energy in an ecosystem, thereby increasing the chances of survival of species, regulating the population size.
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- 30. FOOD CHAIN v/sFOOD WEB
- 31. 2.i.c. ECOLOGICAL PYRAMIDS The steps of trophic level expressed in a diagrammatic way are referred as ecological pyramids. It is depicted by horizontal bars layered upon one another with each bar representing one trophic level. The length of each bar denotes the total number of individuals at that trophic level. The base is formed by food producers, the tip is formed by the top carnivore with other consumers in between.
- 33. ECOLOGICAL PYRAMIDS TheEcological Pyramids are of three categories: Pyramid of numbers Pyramid of biomass Pyramid of energy/productivity.
- 34. Pyramid of Numbers Deals with the relationship between the total NUMBERS of primary producers and subsequent consumers at different trophic levels in an ecosystem. Can be upright or inverted or of any shape. Pyramid of numbers- upright = Grassland ecosystem, Pond ecosystem Pyramid of numbers- inverted/spindle shape = Parasitic Tree Ecosystem, Non parasitic tree ecosystem.
- 35. Pyramid of numbers- Upright The number of individuals is decreased from lower trophic level to higher trophic level. E.g. Grassland ecosystem Pond ecosystem Rotifers
- 36. The numberof individuals is increased from lower level to higher trophic level. The base is represented by producers which are lesser in number than dependent herbivores. E.g. Parasitic Tree ecosystem Pyramid of numbers – Inverted/spindle shaped
- 37. The drawbacksof pyramid of numbers are: It does not take into account the fact the size of organisms being counted in each trophic level can vary. It is very difficult to count the number of all the organisms in a particular trophic level. Hence, the pyramid of number does not completely define the trophic structure for an ecosystem. Pyramid of Numbers
- 38. Pyramid of Biomass To overcome the shortcomings of pyramid of numbers, pyramid of BIOMASS is used. Individuals in each trophic level are weighed instead of being counted. Deals with the relationship between the total DRY WEIGHT of primary producers and subsequent consumers at different trophic levels in an ecosystem. Can be upright or inverted.
- 39. The biomassof the producers is maximum, hence, the base is long and large. The biomass of the next trophic level i.e. the primary consumers is lesser than the producers and so on. E.g. Pyramid of biomass of most land based ecosystems. Pyramid of biomass - Upright
- 40. The biomassof the producers are lesser than the subsequent consumers, hence, the base is small, thus the pyramid assumes inverted shape. E.g. Pyramid of biomass of an Aquatic Ecosystem Pyramid of biomass - Inverted
- 41. Pyramid of Energy It is the most suitable tool to compare the functional roles of the trophic system in an ecosystem. Conversion of solar energy to chemical energy. Loss of energy as heat energy at each trophic level, so the subsequent trophic level has lesser energy than the previous one. ALWAYS UPRIGHT Energy pyramid concept helps to explain the phenomenon of biological magnification.
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- 43. FEW EXTRA CONCEPTS: Some concepts which are related to trophic structure of an ecosystem: Bioaccumulation Biomagnification Biotic interaction
- 44. BIOACCUMULATION It refersto how pollutants enter a food chain. It is the increase in the concentration of a pollutant from the environment to the first organism in a food chain. The pollutants must be non-degradable in nature i.e. they cant be metabolized by the living organisms. E.g. Chlorinated hydrocarbons, DDT, Diclofenac, etc.
- 45. BIOMAGNIFICATION Pollutants movethrough various trophic levels in an ecosystem. Biomagnification refers to the tendency of pollutants to concentrate as they move from one trophic level to the next. Concentration of the pollutants increases as we move upwards in the trophic level.
- 46. BIOMAGNIFICATION The pollutantmust be: Non biodegradable Long lived Mobile Soluble in fats Biologically active E.g. Diclofenac poisoning in vultures, etc.
- 47. BIOTIC INTERACTION Livingorganisms in this Earth are interlinked with each other in one way or other. This interaction between the organisms is fundamental for its survival and functioning of Ecosystem as a whole. Types of Biotic interaction are: Mutualism Commensalism Amensalism Competition Predation Parasitism
- 48. MUTUALISM :-both species are benefitted. E.g. Pollination by bees. COMMENSALISM :- one species is benefitted, the other remains unaffected. E.g. Cow dung and Cow dung beetles. AMENSALISM :- one species is harmed, the other remains unaffected. E.g. Antibiosis between penicillium mould and bacteria. COMPETITION :- both species are harmed. E.g. two species eating the same food. PREDATION/PARASITISM :- one species is benefitted, the other one is harmed. E.g. Tiger killing a bison. BIOTIC INTERACTION
- 50. 2.ii. NUTRIENT CYCLING The elements and compounds that make up nutrients move continually through air, water, soil, rock, and living organisms in ecosystems/biospheres in cycles which is called biogeochemical cycles (literally, life-earth-chemical cycles) or nutrient cycles. A concept that describes how nutrients move from the physical environment to the living organisms and subsequently recycled back to the physical environment.
- 51. Essential forlife and its vital function of ecology. For maintenance of sustainable population in a particular ecosystem. C, H, O, N and P as elements and compounds make up 97% of the mass of our bodies and are more than 95% of the mass of all living organism. Based on the nature of the reservoir, there are two types of cycles: Gaseous cycle- where the reservoir is the atmosphere of the hydrosphere. E.g. water, carbon, nitrogen Sedimentary cycle- where the reservoir is the earth’s crust. E.g. Phosphorous NUTRIENT CYCLING
- 52. WATER CYCLE (Hydrologicalcycle) Continuous circulation of water in the Earth-atmosphere-hydrosphere system in all forms (Global cycle). The water cycle is powered by solar energy and involves three major processes—evaporation, precipitation, and transpiration. Major reservoirs are atmosphere, oceans, lakes, rivers, soils, glaciers, snowfields, groundwater, etc. The largest reservoirs/sink are the oceans. Moves from one reservoir to other by the process of evaporation, transpiration, precipitation, runoff, infiltration, etc.
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- 54. CARBON CYCLE Carbonis vital for life to sustain in Earth. Production of carbohydrates through photosynthesis. Component of DNA Formation of coal It is divided into two parts: Short term cycle via atmosphere Long term cycle via accumulation in the aquatic systems. Oceans are the largest reservoir of carbon.
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- 56. Short termcycle: In the form CO2 in the atmosphere. Exchange of carbon between atmosphere and organism via the processes of photosynthesis, respiration and decomposition. Long term cycle: Accumulation as un-decomposed organic matter in peaty layers of marshy soils OR as insoluble carbonates in bottom sediments of aquatic systems which takes a longer time to be released. Trapped in fossil fuels such as coals, oils, natural gases When used its released back into the atmosphere. CARBON CYCLE
- 57. NITROGEN CYCLE NitrogenCycle is a biogeochemical process through which nitrogen is converted into many forms, consecutively passing from the atmosphere to the soil to organism and back into the atmosphere. Essential constituent of protein and is a basic building block of all living tissues. Nitrogen exists in both organic and inorganic forms.
- 58. Atmosphere isthe largest reservoir of nitrogen. Elemental form of nitrogen can not be used directly by most of the living organisms. Hence, nitrogen has to be FIXED and then converted into other forms viz. ammonia (NH3), nitrites (NO2-), nitrates(NO3-) before taken up by plants. 5 processes: Fixation Nitrification Assimilation Ammonification Denitrification NITROGEN CYCLE
- 59. Nitrogen Fixation Atmosphericnitrogen (N2) which is primarily available in an inert form, is converted into the usable form –ammonium ions (NH4+). Nitrogen fixation is accomplished by three different ways : By Biological fixation (Diazotrophs – symbiotic bacteria. E.g. Rhizobium, Azatobactor, etc. ) NITROGENASE ENZYME. By atmospheric phenomenon as thunder and lightening By man using industrial processes
- 60. NITROGEN CYCLE Nitrification 2NH4 ++ 3O2 → 2NO2 – + 4H+ + 2H2O 2NO2 – + O2 → 2NO3 – Assimilation Ammonification : the nitrogen present in the organic matter is released back into the soil and is converted back into Ammonia. Denitrification : Denitrification is carried out by the denitrifying bacterial species- Clostridium and Pseudomonas, which will process nitrate to gain oxygen and gives out free nitrogen gas as a byproduct.
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- 62. PHOSPHOROUS CYCLE Phosphoruscycle is a biogeochemical process that involves the movement of phosphorus through the lithosphere, hydrosphere and biosphere. It forms a significant part of the structural framework of DNA and RNA, and important component of ATP. Very slow process- sedimentary cycle. (EARTH CRUST-largest reservoir) Various processes help to wash the phosphorus present in the rocks into the soil. Phosphorus IN THE FORM OF PHOSPHATES is absorbed by the organic matter in the soil which is used for various biological processes.
- 63. Following arethe important steps of phosphorus cycle: Weathering of Phosphate (PO43-) containing rocks. E.g. Phosphorite Absorption by Plants and Animals Return to the Environment through Decomposition PHOSPHOROUS CYCLE
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- 65. SULPHUR CYCLE Sulfurcycle is the circulation of Sulphur in various forms through nature. Component of proteins and amino acids. Sulphur is released into the atmosphere by: Burning of fossil fuels in the form of Sulphur dioxide (SO2). Volcanic activities (SO2 and H2S) Decomposition of organic molecules Weathering of sulphates (SO42-) containing rocks. MARINE SEDIMENTS ARE THE LARGEST RESERVOIR OF SULPHUR.
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- 67. ACTIVITY: POINTS TOPONDER ANTHROPOGENIC ACTIVITIES AND ITS IMPACT OVERUTILIZATION of RESOURCES POLLUTION??? RELEVANT EXAMPLES !!!! AGRICULTURE CLIMATE CHANGE BIODIVERSITY THREAT
- 68. 2. iii. PRODUCTIVITY The rate of biomass production is called productivity. Productivity is a rate function and is expressed in terms of dry matter produced or energy captured per unit area of land, per unit time. It can be expressed as: energy in calories/cm2/yr. dry organic matter in g/m2/yr. The productivity of different ecosystems can be easily compared.
- 69. FACTORS AFFECTING PRODUCTIVITY Solar radiation and temperature. Moisture, i.e. soil moisture, fluctuation of precipitation, and transpiration. Mineral nutrition. Biotic activities. Impact of human populations
- 70. 2.iii.a. PRIMARY PRODUCTIVITY It is the rate at which radiant solar energy is converted into chemical organic substance by photosynthesis or chemosynthesis by the primary producers. It has two aspects: Gross primary productivity (GPP)- The total solar energy trapped in the food material by photosynthesis/chemosynthesis. Net primary productivity (NPP)- The amount of energy-bound organic matter created after respiration. NPP = GPP-Respiration.
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- 72. 2.iii.b. SECONDARY PRODUCTIVITY The rates at which the heterotrophic organisms resynthesize the energy- yielding substances are called secondary productivity. The amount of organic matter stored by herbivores or carnivores is known as secondary production.
- 73. 2.iv. ECOLOGICAL HOMEOSTASIS The tendency of a biological system to resist changes. Maintain itself in a steady equilibrium state i.e. in balanced state. “ Ecological/Ecosystem Homeostasis is its inherent property resist change”
- 74. Homeostasis Homeostasis isthe maintenance of stable equilibrium, especially through physiological (through bodily part functions). E.g. Cooling your body through sweating processes. Organisms try to maintain the constancy of its internal environment despite varying external environmental conditions that tend to upset their homeostasis. Negative (-ve) feedback loops- Deviation counteracting mechanisms. Positive (+ve) feedback loops- Deviation accelerating mechanisms.
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- 76. -ve feedback loopexample:-
- 77. NEGATIVE FEEDBACK LOOPS= INHIBITION POSITIVE FEEDBACK LOOPS = PROMOTION
- 78. Positive feedback loopsexample :-
- 79. Homeostasis mechanisms: Regulate Conform Migrate Suspend
- 80. Regulate Control orRegulation. Some organisms can maintain homeostasis by physiological functions. E.g. Thermoregulation by warm blooded animals. Mammals and birds ENDOTHERMS
- 81. Conform An overwhelmingmajority of animals and nearly all plants cannot maintain a constant internal environment. Their body temperature changes with the ambient temperature ECTOTHERMS
- 82. Migrate The organismcan move away temporarily from the stressful habitat to a more hospitable area and return when a stressful period is over. E.g. Keoladeo National Park, Bharatpur, Rajasthan- Migration of Siberian Crane
- 83. Suspend Suspend metabolicactivities. E.g. Hibernation Aestivation.
- 84. ECOSYSTEM HOMEOSTASIS AllEcosystems regulate and maintain themselves under a set of environmental conditions to achieve a steady state of DYNAMIC EQUILIBRIUM. If any stress tries to cause a deviation, then the system has its own mechanisms to counteract these deviations which are known as –ve feedback mechanisms. E.g. In a pond ecosystem, if the population of zooplankton increases, they consume a large number of the phytoplankton and as a result, food would become scarce for zooplanktons. When the number of zooplanktons is reduced because of starvation, the phytoplankton population start increasing. After some time, the population size of zooplankton also increases.
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- 86. The homeostaticcapacity of ecosystems is not unlimited as well as not everything in an ecosystem is always well regulated. If the stress is too high positive feedback mechanisms start operating which leads to death of species and collapse of the ecosystem. E.g. Human activities impact ECOSYSTEM HOMEOSTASIS
- 87. 2.v. ECOLOGICAL SUCCESSION Communities are dynamic, changing more or less regularly over time and space. Variations in climatic factors Activities of the species of the communities themselves Human interventions Occurrence of relatively definite sequence of communities over a period of time in the same area until a stable, mature community develops (CLIMAX COMMUNITY) is ECOLOGICAL SUCCESSION. ECOLOGICAL DEVELOPMENT
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- 89. ECOLOGICAL SUCCESSION Orderlyand continuous changing process Reasonably directional Somewhat predictable. Not unlimited It culminates in a stabilized ecosystem in which maximum biomass and functions between organisms are maintained per unit of available energy.
- 90. Primary v/s SecondarySuccession Primary Succession Starts from primitive substratum, where there was no previously any sort of living matter. The first group of organisms establishing there are known as PIONEERS/ Primary Community/Primary Colonizers. Secondary Succession Starts from previously built up substrata with already existing living matter. Are relatively rapid
- 91. GENERAL PROCESS OFSUCCESSION NUDATION INVASION COMPETITION and COACTION REACTION STABILISTION (CLIMAX)
- 92. NUDATION Development ofa bare area without any form of life They area may develop due to: TOPOGRAPHIC- soil erosion, landslide, etc. CLIMATE- glaciers, dry period, fire. BIOTIC- man made
- 93. INVASION Successful establishmentof a species in a bare area Species actually reaches this new site from any other area Migration Establishment- ecesis Aggregation
- 94. Competition and Coaction,Reaction and Stabilization Competing for space and nutrients. Reaction- modification of the environment The sequence of communities that replaces one another in the given area is called a SERE, and various communities constituting the sere are called SEREAL STAGES. Stabilization (Climax)- Climax community and this stage is climax stage
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- 98. ECOTONE Ecotone isa transitional area between two biological communities such as forest and grassland. E.g. Estuaries, mangrove ecosystem, etc. It contains a large variety of species of fauna and flora as the area is influenced by both the bordering ecosystems. It may be wide or narrow It could contain species that are entirely different from those found in the bordering systems Ecotones can be natural or man-made. For example, the ecotone between an agricultural field and a forest is a man-made one
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- 100. ECOTONES Edge effectsrefer to the changes in population or community structures that occur at the boundary of two habitats. Generally, there is a greater number of species found in these regions (ecotones) and this is called the edge effect. The species found here are called edge species. They can act as buffer zones offering protection to the bordering ecosystems. They serve as a bridge of gene flow from one population to another because of the larger genetic diversity present. Ecotones are also a sensitive indicator of global climate change