EVS Notes- Ecosystem, Biotic, Abiotic, Ecological succession

EVS Unit 1

1. Environmental Studies

2. The word environment is derived from the French word ‘ environner ’ which means to ‘ encircle or surround ’. Environment Protection Act (1986) defines environment as " the sum total of water, air, and land, their interrelationship among themselves and with the human beings, other living beings and property.” Environment Studies deals with the interactions of the environment’s P hysical (climate, geology, topography, and natural processes such as erosion, weathering, and the movement of water), C hemical ( nutrients, pollutants, gases, and minerals) , and B iological components (all living organisms, including plants, animals, microorganisms) It also studies the relationships and effects of these components with the organisms in the environment.

3. Environmental studies is an interdisciplinary or multidisciplinary subject that tells us how nature works and how things in nature are interconnected . It also includes the effect of human activities on nature and vice-versa".

4. In simpler terms, Environmental Studies is a field that explores everything that affects humans, other living creatures, and even the non-living aspects of our world. It covers a wide range of topics because it helps us understand the natural world and how human actions impact it. This field brings together knowledge from different areas of study to help us appreciate the importance of our environment and find ways to sustain human civilization with the limited resources available on Earth.

5. Environmental studies as a subject has a wide scope. It includes a large number of areas and aspects, which may be summarized as follows: Scope of Environmental Studies Natural resources - their conservation and management Ecology and Biodiversity Environmental pollution and control Human population and environment Social issues - in relation to development and environment

6. Ecosystem An ecosystem is a geographic area where plants, animals, and other organisms, as well as weather and landscape, work together to form a bubble of life. An Ecosystem can simply be defined as a system comprising all living organisms existing with one another in a unit of space interacting with abiotic components.

7. Ecosystem A group of organisms interacting among themselves and with the environment is known as an ecosystem. Living organisms rely on both the living and non-living environment for survival, with constant interactions between them and among different species. This interconnected system, encompassing all components and interactions, is called an ecosystem . Examples: Pond, lake, ocean, forest and desert are some of the examples of the ecosystems.

8. Structure of Ecosystem ECOSYSTEM BIOTIC (LIVING) ABIOTIC (NON-LIVING) Producers Consumers Decomposers Herbivores Carnivores Air Water Energy Soil

9. BIOTIC (LIVING) All living components of the environment such as human beings, animal kingdom, plants, and microbes (bacteria and fungi). Further categorized on the basis of “SELF- FOOD PRODUCING CAPABILITY’’. Producers Consumers Decomposers

10. BIOTIC (LIVING) This category includes organisms, green plants, bacteria, and algae , which contain chlorophyll . They are able to absorb solar energy to convert it into usable chemical energy by using carbon dioxide and water in the presence of sunlight and chlorophyll. This process whereby carbon dioxide is absorbed by the plants and oxygen is released into the atmosphere is known as photosynthesis. This transformation is shown as: 6CO + 6H O --------> C H O + 6O Producers (Autotrophs): 2 2 6 12 6 2

11. They are animals who cannot produce their own food. They obtain the same from plants or other animals for survival. Consumers (Heterotrophs): (a) Primary Consumers (Herbivores): The animals which obtain their food from green plants are called as primary consumers. Cow, goat, horse, rabbit, deer, cattle, and grasshopper are some examples (b) Secondary Consumers (Carnivores): The animals that live on the flesh of the primary consumers are known as secondary consumers. For example, frogs, lizards, cats, dogs, snakes, birds, many more.

12. (c) Tertiary Consumers (Top Carnivores): These are the large carnivores, which eat the flesh of the secondary consumers. Lions, tigers, and vultures are some examples. Consumers (Heterotrophs):

13. Bacteria, insects, worms and fungi (microbes) eat away the dead bodies of the producers and consumers . The released by-products are water, carbon dioxide, nitrogen, phosphates, sulphates, etc. These simple substances are re-used or absorbed from the soil, water and air as nutrients by the producers, resulting in a cyclic exchange of materials between the biotic and abiotic components of the ecosystem. The decomposers are known as saprotrophs. They are also called as reducers, as these are able to degrade or remove the dead bodies of organisms . Decomposers (Reducers)

14. ABIOTIC (NON-LIVING) The non-living or physical environment in an ecosystem forms the abiotic component. It is comprised of minerals (like calcium, sodium. potassium, nitrogen, etc. required for growth) and climatic factors (like rainwater, carbon dioxide, light, temperature, humidity, moisture, solar radiation, salinity of soil, etc.). All biotic organisms interact with the abiotic component of the environment as well as among themselves.

15. QUIZ: The study of interaction between the living species and the environment is called: (a) biology.(b) antology .(c) ecology. (d) zoology. ecology The interdependence of the living organisms among themselves and with the environment is called: (a) ecology.(b) ecosystem.(c) biology.(d) antology . ecosystem Ecosystem consists of biotic components only. only abiotic component. both biotic and abiotic components. None of the above both biotic and abiotic components. WELL DONE

16. Functioning of Ecosystem PRODUCTIVITY FOOD CHAINS AND FOOD WEBS TROPICAL LEVELS ECOLOGICAL SUCCESSION

17. PRODUCTIVITY FARM FOREST They both have green plants, which are like the chefs of our ecosystem because they make food using sunlight. These chefs are called Producers (autotrophs). Productivity is like how fast the chefs in these places can make food. It's about how much food they can cook up in a certain amount of time and space.

18. PRODUCTIVITY Gross Primary Production (GPP): This is the total amount of food that the chefs (autotrophs) make by using sunlight. It's like all the dishes they prepare. In our forest , the chefs (plants) make a lot of food because they have plenty of sunlight. So, they have a high GPP . But on the farm, the chefs (crops) also make a good amount of food, but not as much as in the forest because they have less sunlight. So, their GPP is lower . The rate of food production in unit time per unit area is called productivity. The rate of primary production depends upon the availability of solar energy and the amount of energy expenditure by respiration and other maintenance process.

19. PRODUCTIVITY Net Primary Production (NPP): This is the amount of food that's left after the chefs (plants) use some of it for their own energy. It's what's available for all the other creatures (heterotrophs) in the neighborhood to eat. In the forest , even though they make a lot of food ( high GPP ), they also use a lot of it for themselves or in respiration . So, there's not much food left for others (low NPP) . For instance: It's like a fancy restaurant that makes delicious food but eats a lot of it themselves. On the farm , the chefs (crops) use less food for themselves, so there's more left for others (high NPP). For instance: It's like a place where the chefs make good food and share it generously.

20. FOOD CHAINS AND FOOD WEBS A food chain shows how each living organism obtains its food . The food produced by an autotroph (plants) is eaten by primary consumers (herbivores), which are eaten by secondary consumers (carnivores). This, in turn, becomes food for Tertiary Consumers (top carnivores) and the process of providing food as well as the energy source for other organisms continues. Ultimately, the dead organism is decomposed by different decomposers (bacteria, fungi, microbes, etc.). There is recycling of nutrients into the soil on which plant life grows.

21. FOOD CHAIN

22. A food web is a way to show how different living things in an ecosystem eat and interact with each other. It's like a map that helps us understand who eats whom in nature. Example : For example, a basic food chain could be "Grass -> Rabbit -> Fox," where the grass is eaten by the rabbit, which is then eaten by the fox. In a food web , for instance, a plant (grass) is eaten not only by rabbits but also by deer and insects. Similarly, a fox might eat not only rabbits but also birds, and other prey. It illustrates the many ways energy and nutrients flow through an ecosystem.

23. FOOD WEB

24. TYPES OF FOOD CHAINS GRAZING FOOD CHAIN DECOMPOSER OR DETRITUS FOOD CHAIN

25. GRAZING FOOD CHAIN This chain starts from green plants and algae. From this, the energy passes through various levels of consumers, viz. grazing herbivores to omnivores and then to carnivores. Human beings generally belong to a grazer chain as either primary or secondary consumers.

26. DECOMPOSER OR DETRITUS FOOD CHAIN This chain starts from dead organic matter and goes to detritus-feeding organisms and on to their predators. 'Detritus' generally include fallen leaves, plant parts or dead animal bodies. ' Detrivores ' are consumers of dead matter like soil miles, worms, bacteria and fungi. Detrivores Detritus Predators

27. TROPICAL LEVELS (ECOLOGICAL PYRAMIDS) Plants (Producers) Herbivores (Primary Consumers) Small Carnivores (Secondary consumers) Top Carnivores (Tertiary consumers) Trophic Level I Trophic Level II Trophic Level III Trophic Level IV

28. Scientist Charles Elton was the first to observe in 1927 that the number of animals present at the top of the trophic level was much less compared to the number of animals present at the base of the food chain . He plotted his findings on a graph in the form of a pyramid-like structure. There are three types of ecological pyramids: Upright Pyramid of Number Partly Upright (Spindle Shape) Pyramid of Number Inverted Pyramid of Number

29. 1. Pyramid of numbers The pyramid of numbers shows the number of organisms at each trophic level in a food web. The number of organisms found in any one level decreases on going up the pyramid, to the higher trophic levels. The number pyramid varies from ecosystem to ecosystem. There are three types of pyramids of numbers, depending upon the nature of the food chain. Upright Pyramid of Number Partly Upright (Spindle Shape) Pyramid of Number Inverted Pyramid of Number

30. Pyramid of numbers Upright Pyramid of Number This type of pyramid is found in the grassland and aquatic ecosystem. For example, in grassland ecosystem, the number of grasses (producer) is always high followed by primary consumers (herbivores like rabbits and grasshoppers. The secondary consumers (carnivores like snakes and lizards) are even lesser. Finally, the top carnivores (such as hawks) are the least in number. Thus, the pyramid is upright.

31. Pyramid of numbers It is observed in the forest ecosystem . For example, a large tree supports larger number of herbivorous birds . This is turn are eaten by carnivorous birds like falcon and eagle, which are smaller in number. This results in a spindle-shaped pyramid. Partly Upright (Spindle Shape) Pyramid of Number

32. Pyramid of numbers In case of parasitic food chain , the ecological pyramid is always inverted. This is because a single plant (producer) supports a large number of herbivores (primary consumers). These, in turn, support a large number of parasites, which provides food to more hyperparasites. Inverted Pyramid of Number

33. 2. Pyramid of Biomass It represents the abundance of biomass of organisms at each trophic level in an ecosystem at any time . It is like a stack of blocks that shows how much living organisms there is in different parts of nature. Each block represents a group of living things, like plants or animals. But instead of counting them, we weigh them . In places like forests or grasslands, there are lots of plants , so they make up the biggest , heaviest block at the bottom of the stack. Then, as you go up the stack, each block gets smaller because there are fewer animals that eat the plants. This makes the pyramid look like it's standing upright.

34. 3. Pyramid of Energy The reason the Pyramid of Energy looks like an upright tower with a wide base is because of a rule from science called the " second law of thermodynamics. " This rule says that when energy is passed from one organism to another in a food chain, some of it gets lost or used up along the way. So, at the very bottom of the pyramid, where you have things like plants , there's a lot of energy available because they capture it from the sun. But as you move up the pyramid and animals eat other animals, some of that energy is lost as heat when they breathe, move, and do other things.

35. 3. Pyramid of Energy Because of this loss of energy at each step, there's less and less energy available for the next level of animals. That's why the pyramid starts wide at the bottom (lots of energy) and gets narrower as it goes up (less energy). It's like showing us how much energy is left for each group of animals in the food chain. Energy is expressed per unit area per unit time, i.e., KJ m²/year . The energy contained at each tropic level decreases by 90 percent at each successive step as the energy acquired by any organism cannot be fully transferred to the higher trophic level.

36. ECOLOGICAL SUCCESSION When a sequence of communities are displaced by large-scale natural or human-caused disaster, succession occurs . This cycle repeats itself, with one group displacing another until a stable, mature community emerges. The  pioneer community   is the first plant to colonize a region . The  climax community is the last stage of succession . For example, when an abandoned farm field is left alone for several years , it gradually transforms into a meadow , then a few bushes, and finally, trees entirely fill in the field, resulting in a forest.

37. ECOLOGICAL SUCCESSION There are two main types of succession: Primary Succession: When there is no plant life on the landscape, such as after a lava flow or glacial retreat, primary succession occurs. It occurs on entirely new land without any established soil such as river deltas, sand dunes, or exposed rocks. The first community is always autotrophic (plants) and is usually known as the pioneer community . Its evolution occurs in a purely inorganic environment. The continuance of the life cycle of the pioneer community makes the environment rich in organic matter. It helps the succession of the second community by establishing a layer of soil for future organisms to utilize through the germination of seeds. This increases the diversity of the species.

38. ECOLOGICAL SUCCESSION

39. ECOLOGICAL SUCCESSION Secondary Succession: When a disturbance affects a climax community or intermediate community, secondary succession occurs. The succession cycle is restarted , but not completely— soil and nutrients are still present. As a result, secondary succession can also be described as the establishment of biotic communities in a sequential order following the entire or partial destruction of the previous community. After a forest fire, for example, that destroys all of the adult trees on a given terrain, grasses may emerge, followed by shrubs and a variety of tree species, until the community that existed before the fire reappears.

40. ECOLOGICAL SUCCESSION

41. Thanks