Ecosystem Concepts


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Ecosystem Concepts

  1. 1. Ecological System Concept (Concept of Ecosystem) Ecosystem is the basic structural andEcosystem is the basic structural and functional unit of ecology.functional unit of ecology. “Ecosystems are the basic units of nature on the face of the earth”. An ecosystem is an ecological unit, or a subdivision of the landscape, or a geographic area that is relatively homogeneous and reasonably distinct from adjacent areas. J.W. Marr, 1961 Tansley, 1935 Definition
  2. 2. Ecosystem – another view • Ecosystem is a spatial functional structure • The space may be geographically large or small • Largest ecosystem. e.g., Planet earth • Smallest ecosystem (microcosm): • e.g. a handful of soil and moss in a sealed jar.
  3. 3. Components of an Ecosystem Abiotic components- (geographical, climatic,(geographical, climatic, physicochemical characteristics)physicochemical characteristics) Biotic components- (Plants, animals, microbes)(Plants, animals, microbes)
  4. 4. Ecological Cycle
  5. 5. Ecosystem Structure
  6. 6. Mountain ecosystem – Removal of forest cover Evergreen forests – Over exploitation of forest resources Coral reefs – Human interference, Dynamite fishing River ecosystem – Pollution Land ecosystem – Dumping solid wastes Specific influence of human beings on sensitive Ecosystems
  7. 7. Properties of Ecological Systems 1. Networks –Interdependence, diversity, complexity 2. Boundaries- Scale and limits 3. Cycles – Recycling of resources and partnership 4. Flow –through – Energy and resources 5. Development – Succession and co-evolution 6. Dynamic balance- Self – organization, flexibility, stability, sustainability
  8. 8. Positive feedback Set point Negative feedback Deficiency Excess Negative feedback Death Positive feedback Death Homeostatic Plateau A Cybernetic system of Ecosystem Regulation
  9. 9. Biotic component 1 Biotic component 2 Biotic component 3 Input Output Ecosystem Output Input Output Input Output Nutrient Flow model
  10. 10. Plant Cow Man Input Sunlight Output - Input Chemical energy in leaves Output - input Chemical energy in meat of cow Output Heat given off during Series open system components
  11. 11. System X Y Z Subsystem X Subsystem Y Subsystem Z Inputs Outputs Open system with components
  12. 12. Features of an open systemFeatures of an open system Open systems process inputs and produce outputs The amount of output produced is directly related to the amount of input received.
  13. 13. Features of Complex systems • Complex systems are composed of many interconnected and interacting subunits. • They are capable of adaptation and self- organization.
  14. 14. Open systems All living systems are open systems. A cell is an open system because it constantly acquires food from outside itself and eliminates wastes. It gives off heat as it carries on chemical processes (respiration).
  15. 15. Biological SystemsBiological Systems Hierarchical SystemHierarchical System Genetic systems Cell systems Organ systems Organismic systems Population systems Ecosystems
  16. 16. Dynamics of ecosystems Bio-systems Energy, Gases inorganic matter water organisms Subsystems Plants → animals Microbes Energy Nutrients Gases Inorganic matter Inputs Outputs
  17. 17. Gaseous Nutrient cycles Sedimentary nutrient cycles Biogeochemical cycles and population – Evolution spiral Outputs Heat radiated into space Inputs Sunlight (energy) The earth as a single system Earth Ecosystem
  18. 18. Functional aspects Inputs Energy, Nutrients, Gases, Inorganic matter Photosynthesis Herbivory Carnivory Decomposition Energy Nutrients Gases, Inorganic matter Outputs Biosystems
  19. 19. Solar energy Photosynthesis Solar energy is converted to chemical energy Respiration Chemical energy is used to do work Ecosystem Degraded Waste Energy Energy flow in an Ecosystem
  20. 20. Ecological Pyramids Pyramid of numbers: No of individuals at each trophic level Graphic representation of tropic structure and function of an ecosystem. Hawks Hyperparasites (microbes) Frogs Parasites (Lice, bugs) Insects Birds Grasses Trees
  21. 21. Pyramid of biomass: Total biomass (dry matter) at each tropic level Fox Rabbit Herbs Pyramid of energy: Amount of energy present at each trophic level. Top Carnivores Carnivores Herbivores Producers
  22. 22. Energy relationshipEnergy relationship
  23. 23. Energy cycleEnergy cycle
  24. 24.  At every trophic level there is 90% loss of energy (respiration, activity).  Only 10% energy is transferred from one trophic level to the other.  There is one-way flow of energy. Nutrient Cycling Nutrients like C, N, S, O, H, P etc. Move in circular paths. Hydrological cycle Nitrogen cycle Carbon cycle Phosphorous cycle Energy flow in an ecosystem
  25. 25. Functional Attributes Food chains The sequence of feeding relationships in an ecosystem is called food chain. Trophic structure Each organism in the ecosystem is assigned a feed level or trophic level.
  26. 26. Simple food web model Producer : Pond grass Herbivore : Water insects Carnivore : Large fish Herbivore : Small fish Carnivore : Duck Top Carnivore : Man
  27. 27. Sunlight Producer Carnivore Herbivore Heat Produced Decomposers Simple Food – Chain Model
  28. 28. Kinds of food chain 1. Grazing food chain – Starts with green plants and ends with carnivores. Grass → Rabbit→ Fox 2. Detritus food chain – Starts with dead organic matter and ends with predators. Mangrove ecosystem Leaf litter →Saprotrophs / detritivores (crabs) →Small carnivorous fish → Large Carnivorous fish - a complex inter connected network of food chains at different trophic levels. Food web
  29. 29. Significance of food chain 1.Food chains maintain energy flow and nutrient cycling. 2.Food chains maintain ecological balance by regulating population size. 3.Food chains biologically magnify toxicity of some chemicals.
  30. 30. Kinds of Ecosystems Ecosystem Terrestrial Aquatic Man-engineered e.g. Forest, Desert Grassland, Steppe, Savanna e.g. Agricultural land use, Urban / industrial land use Freshwater Marine Lentic Lotic e.g. Ponds, Lakes e.g. Streams, Rivers Coastal ecosystems Mangrove ecosystems Seagrass ecosystems Coastal lagoon ecosystems Coral reef ecosystems Delta ecosystems Estuarine ecosystems Sandy beach ecosystems Rockyshore ecosystems Coastal upwelling
  31. 31. Ecosystems
  32. 32. Threats from Agricultural Ecosystems  Ecological simplicity – large monocultures.  Ecosystem instability.  High degree of biological uniformity (minimum genetic variability).  Widespread disease outbreaks or pest infestations.  Depletion of fertilizers (nutrients) and energy (fossil fuels).  Elimination of other crop species and other ecosystems.