ECOSYSTEMS

1. Chapter - 3 ECOSYSTEMS

2. Ecosystem An ecosystem is a natural unit consisting of all plants, animals, and micro-organisms in an area functioning together with all the non-living physical factors of the environment. According to British ecologist Arthur Tansley (1935), an ecosystem is a system that arises from the integration of all living and non-living factors of the environment. Ecology Ecology is the study of how living and non-living factors affect each other in an environment. An ecosystem is the basic and functional unit of ecology.

3. Classification of ecosystem e.g. (aquaria, garden, dams & cropland of maize, wheat, rice).

4. Natural vs Artificial Ecosystem

5. Natural Ecosystems Man-made Ecosystems What is the different between natural and man Made ecosystem?

6. Structure of ecosystem: Components Or Organic, Inorganic and climatic factors

7. Structure of an Ecosystem Living (Biotic) Components • Producers • Consumers ( primary, secondary and tertiary) • Decomposers (Maintains biological cycle) Non-living (Abiotic) Components • Organic • Inorganic • Physical

8. Biotic Components of Ecosystems • Producers (or autotrophs) • Green plants and some bacteria which manufacture their own food. • Consumers (or heterotrophs) • Animals which obtain their food from producers • Primary consumers • Secondary consumers • Tertiary consumers • Decomposers • Bacteria and fungi that decompose dead • organic matter and convert it into • simpler parts

9. Abiotic Components of an Ecosystem Organic Carbohydrates Lipids Proteins Inorganic Water Ammonia Gases Climatic Rainfall Humidity Physical Temperature Heat, Light

10. Producers • Producers make their own food • Green plants use energy from the sun to make food • Producers are on the bottom of the food chain

11. Consumers • Consumers hunt, gather, and store food because they cannot make their own.

12. Three Types of Consumers • Herbivores • Carnivores • Omnivores

13. Herbivores • Animals who eat plants such as: • grasshoppers • rabbits • squirrels • deer • pandas

14. Carnivores (secondary consumers) • Meat eaters and feed on herbivores are known as secondary consumers • Eg dog, fox, wolf etc.

15. Carnivores (tertiary consumers) • Carnivores which prey upon other carnivores but are not eaten themselves. They constitute the terminal end of predator of grazing food chain • tigers • lions • hawks

16. Omnivores • Animals who eat both plants and animals such as: • humans • bears

17. Decomposers • Organism that feed on dead and decaying matter and convert into organic material are called decomposers • They help in nutrient recycling and known as recycling agent of the nature • In absence of recycling nutrients earth would be converted into a vast dump of dead organism • Microorganisms that are able to break down large molecules into smaller parts

18. Abiotic components • Physical factors: Sunlight, shade, intensity of solar flux, length of day , temperature, annual rainfall (precipitation), latitude, altitude, soil type, water availability • Chemical factors: Availability of essential nutrients such as carbon, nitrogen, phosphorous, potassium, oxygen, sulfur, percentage of water and air in soil, salinity of water, oxygen dissolved in water

19. Limiting factor Factors which restrict the further growth of population Availability of food Water Shelter Space

20. Functions of an Ecosystem • Food chain and food web • Energy flow • Cycling of matter (chemicals)

21. Food Chain Food Web The interlocking pattern formed by several food chains that are linked together is called a food web. The transfer of food energy from the source (plants) through a series of organisms by repeated eating and being eaten up is referred as food chain.

25. Food webs • It is not possible to depict the real world by means of simple food chain, because the interconnection between different trophic level in real world are extremely complex • Various food chain are interlinked with each other and these interlocking pattern formed by several food chain linked together are called food web

29. Food Chain: Grassland Ecosystem

30. Food Web

31. Significance of food chain • Food chains are important for maintaining and regulating the population size • Ecological balance • biomagnification

32. Flow of Energy in an Ecosystem First Law of Energy Energy can neither be created nor be destroyed Second Law of Energy No energy transformations are 100% efficient Ten-percent Rule of Energy Only 10% of food energy is transferred from one trophic level to another Producer → primary consumer → secondary consumer → tertiary consumer (1000 Kcal) (100 Kcal) (10 Kcal) (1 Kcal)

33. Biogeochemical Cycling The cyclic movement of minerals from their reservoirs (air, water, and soil) to the living components and back to the reservoirs is called nutrient cycling or biogeochemical cycles.

34. Carbon Cycle Nitrogen cycle Phosphorus Cycle

35. Ecological Pyramid • The graphical representations of different trophic levels in an ecosystem is known as ecologicalpyramid . • They are used to illustrate the feeding relationships between organisms. • Types of Ecological Pyramids • Pyramid of number • Pyramid of biomass • Pyramid of energy

36. Pyramid of Number Pyramid of number is used to show the number of individuals in each trophic level. It is upright in case of grassland and pond ecosystems. In some cases, the pyramid of number is inverted. For example, in case of forest ecosystem.

37. Pyramid of Biomass The pyramid of biomass is used to show the total biomass of individuals at each trophic level. It is better than the pyramid of number for showing the relationships between organisms. Pyramid of biomass is upright in case of grassland and forest ecosystems and inverted in case of pond ecosystems.

38. Pyramid of energy Pyramid of energy is used to show the amount of energy transferred between trophic levels. It provides the best representation of the overall nature of an ecosystem. The pyramid of energy flow is always upright because there is always loss of energy while moving from lower trophic level to higher trophic level. Therefore, the energy reaching the next trophic level is always less compared to that in the previous trophic level.

39. Ecological Succession Ecological succession is the gradual process by which ecosystems change and develop over time. It is therefore a series of predictable temporary communities or stages leading up to a climax community. Each stage/temporary community is called a successional stage or seral stage. Each step prepares the land for the next successional stage. All habitats are in the state of constant ecological succession. Types of Succession Primary succession Primary succession refers to a series of community changes which occur on an entirely new habitat which has never been colonized before. For example, a newly quarried rock face or sand dunes. (pioneer and climax community)Secondary succession Secondary succession refers to a series of community changes which take place on a previously colonized, but disturbed or damaged habitat. For example, land obtained after felling trees in a woodland, land clearance, or fire.

40. How does an ecological community develop? Ecological succession describes this process of development, identifying how the community began as well as how and when it stabilizes. Ecological succession: it is the observed changes in an ecological community over time. Changes in an ecological community over time

41. Successional dynamics beginning with colonization of an area that has not been previously occupied by an ecological community, such as newly exposed rock or sand surfaces, lava flows, newly exposed glacial tills, etc.,(finally it has reached the climax community stage) are referred to as primary succession.  Successional dynamics following severe disturbance or removal of a pre-existing community are called secondary succession. Secondary succession is much more commonly observed and studied than primary succession.

42. Ecosystem characteristic that changes during Succession

43. Two primary cause that initiate the ecological succession • An established species and impact of external natural forces, which try to alter the environmental condition of that area • Ex. Hardwood tree replacing red pine • Ecosystem is continuously changing and reorganizing, • ecological succession refers to orderly changes in composition or structure of ecosystem

44. Process of ecological succession • Nudation • Invasion Migration (dispersal) Ecesis (establishment) Aggregation • Competition • Stabilization

45. 1. Nudation: Succession begins with the development of a bare site, called Nudation (disturbance). • 2. Invasion: Invasion of new seeds • Migration: migration of seeds • (ii) Ecesis: It involves establishment and initial growth of vegetation. • (iii) Aggregation: • 3. Competition: As vegetation becomes well established, grow, and spread, various species begin to compete for space, light and nutrients. • 4. Stabilization: A supposedly stable climax community forms.

46. Forest Ecosystem Abiotic Components Inorganic and organic substances found in the soil, climatic factors, e.g., temperature, humidity, rainfall, and light. Biotic Components Producers Different kinds of trees depending upon the climate Consumers Different kinds of primary, secondary, and tertiary consumers, e.g., deer, elephant, moles, snakes, lizards, lion, and tiger Decomposers These are various kinds of bacteria and fungi

47. Forest ecosystem • tropical rain forests (small mammals, reptiles birds, monkeys, predators like tigers, jaguars etc. plant biodiversity Tall tree, dense canopy.) • temperate forests (deciduous plants like oaks, maples, coniferous plants like pines, ferns, lichens and mosses are also found.) • coniferous forests (pine fir) • Tundra (mosses, lichens, grasses and some dwarf trees; animals like arctic foxes, hares, snowy owls; it is fragile ecosystem)

49. Tropical Forest: Vertical stratification with trees in canopy blocking light to bottom strata. Many trees covered by epiphytes (plants that grow on other plants).

50. Temperate Deciduous Forest: Mid-latitudes with moderate amounts of moisture, distinct vertical strata: trees, understory shrubs, herbaceous sub-stratum. Loss of leaves in cold, many animals hibernate or migrate then. Original forests lost from North America by logging and clearing.