Ecosystem introduction, trophic levels can be represented by numbers
- 1. Ecosystem
- 2. ECOLOGY: • The term was first coined by Hons Reiter and Haekel in 1869. • The term ecology (Okekologie) is originated from two Greek words Oikos (eco) - means “house” (or) place of living and “ology” means “the science of (or) the study of. Hence, ecology is the branch of science that deals with the study of the pattern of relations between the organism and their environment. (OR) • Ecology is the study of interactions among organisms (or) group of organisms with their environment. (OR) Ecology is the study of ecosystems. ECO SYSTEM: • In 1935, the British ecologist A.G. Tansley coined the term “eco system”. • The term “eco system” is made up of two Greek words. “Eco” means ecological sphere (or) house (or) place of living (or) surroundings (or) Environment, where living organism does exist while “system” means “group of organisms joined in regular and interdependent manner. Hence, A group of organisms interacting among themselves and with environment is known as ecosystem. (OR) • A system of interaction of organisms with their surroundings (i.e., environment) is called as “ecosystem”. Examples: Pond, lake, ocean, forest and desert…. Etc are some of the examples of the ecosystems.
- 3. CHARACTERISTICS OF ECOSYSTEM • Eco system is the basic functional unit of ecology. • It contains both biotic and abiotic components. • The function of ecosystem is related to the cycling of matter (materials) and flow of energy. • The amount of energy needed to maintain an ecosystem depends on its structure. • Ecosystem passes from a less complex state to more complex state, which is called as “ecological succession”.
- 4. CLASSIFICATION OF ECOSYSTEM: • The ecosystem can be generally classified into two types: 1. Natural Ecosystem 2. Artificial Eco system 1. NATURAL ECOSYSTEM: • A natural ecosystem is developed and governed by nature. • These are capable of operating and maintaining themselves without any major interference by man. • The following are the two types of natural ecosystem based on their habitat. 1. Terrestrial Ecosystem 2. Aquatic Ecosystem Terrestrial Ecosystem: • This ecosystem is related to land. Examples: Grassland ecosystem. Forest ecosystem, and Desert ecosystem etc. Aquatic Ecosystem: • This ecosystem is related to water, it is further sub divided into two types based on salt content. i. Fresh Water Ecosystem: a. Running Water Ecosystems Examples: Rivers, streams (small narrow rivers) b. Standing Water Ecosystems Examples: Pond, lake & well, etc ii. Marine Ecosystem: Examples: seas and sea shores 2. MAN MADE (OR) ARTIFICIAL ECOSYSTEM: An artificial ecosystem is created and maintained by man for his different needs. Examples: Reservoirs, Artificial lakes and gardens, etc.
- 5. STRUCTURE (OR) COMPONENTS OF AN ECOSYSTEM: • The term structure refers to various components. So, the structure of an ecosystem explains the relationship between the abiotic (non-living) and the biotic (living) components. • Each and every ecosystem has two major components are: 1. Biotic (living) components: The living component of an ecosystem is called “Biotic component”. Examples: Plants (Producers) Animals (Consumers) and Micro Organisms (Decomposers) The biotic components of an ecosystem are classified into three types based on how they get their food. A. Producers (Autotrophs) : Plants B. Consumers (Heterotrophs) : Animals C. Decomposers (Saprotrophs): Microorganisms Producers (or) Autotrophs (Auto=self, troph=feeder) • Self food producing organisms are known as autotrophs. Examples: All green plants and trees. • Producers synthesize their food themselves through photosynthesis. Hence they are also called “Photo autotrophs”. (photo = light) Consumers (or) Heterotrophs (Hetero = other, troph = feeder: • Consumers are organisms, which cannot prepare their own food and depend directly (or) indirectly on the producers. Examples: Plant Eating Species: Insects, rabbit, goat, deer, cow, etc. Animals Eating Species: Fish, lions, tigers, etc.
- 6. • Depending upon the food habits the consumers are divided into four types. i. Herbivores (or) Primary Consumers (Plant Eaters) ii. Carnivores (or) Secondary Consumers (Meat Eaters) iii. Omnivores (or) Tertiary Consumers (With plant & meat eaters) iv. Detritivores (dead organism eaters) Herbivores: (Herbi = the green plant & Vorare = to devour) Animals that eat only plants are called Herbivores. • They directly depend on the plants for their food. So they are called Plant eaters. Examples: Insects, goat, deer, cow, horse, etc. Carnivores: (Carne = flesh meat & Vorare = to devour) Animals that eat other animals are called carnivores. • They directly depend on the herbivores for their food. Examples: Frog, cat, snake & foxes, etc. Omnivores: (Omni = whole comes from “ohm” & Vorare = to devour) • Animals that eat both plants and animals are called omnivores. • They depend on both herbivores and carnivores for their food. Examples: humans, tigers, lions, rats and fox etc. Detritivores: (Detritifeeder) • Animals that eat dead organisms and waste of living are called detritivores. Examples: beetles, termites, ants, crabs, earthworms, etc.
- 7. Decomposers (or) Saptrotrophs: (Sapros = Rotten, trophos = feeder) • Decomposers attack the dead bodies of producers and consumers and decompose them into simple compounds. During the decomposition inorganic nutrients are released. • The organisms which break down the complex compounds into simple products are called decomposers (or) reducers. Examples: micro-organisms such as bacteria and fungi, etc. 2. Abiotic Components: • The non-living component of an ecosystem is called “abiotic component” These non-living components enter the body of living organism, take part in metabolic activities and then return to the environment. The abiotic component of the ecosystems divided into three portions. 1. Climate factors : Solar radiation, temperature, wind, water current, rainfall, etc. 2. Physical factors : light, fire, soil, air, etc. 3. Chemical factors : Organic and Inorganic substances.
- 8. FUNCTION OF AN ECOSYSTEM: • The function of an ecosystem is related to the cycling of materials (matter) and flow of energy. Types of functions: • Functions of an ecosystem are of three types: 1. Primary Function: The producers (plants) can make their food themselves through photosynthesis. This process is called primary function of eco system. Examples: All green plants and trees. 2. Secondary Function: The consumers (animals and humans) cannot make their own food. They are always depending upon the producers for their energy. This is called secondary function of eco system. 3. Tertiary Function: Decomposers attack the dead bodies of consumers and producers and decompose them into simpler compounds. During the decomposition inorganic nutrients are released. Examples: Micro organisms like bacteria and fungi, etc. The functioning of an ecosystem may be understood by studying the following terms: A. Food chains B. Food webs C. Food pyramids (or) Energy pyramids D. Energy and material flow.
- 9. Food chain, food web & Ecological Pyramids
- 10. Energy Flow Through an Ecosystem – Trophic Levels A trophic level is the representation of energy flow in an ecosystem. The trophic level of an organism is the position it occupies in a food chain. Trophic level interaction deals with how the members of an ecosystem are connected based on nutritional needs.
- 11. Energy flows through the trophic levels from producers to subsequent trophic levels is unidirectional. Energy level decreases from the first trophic level upwards due to loss of energy in the form of heat & metabolic processes at each trophic level. This energy loss at each trophic level is quite significant. Hence, there are usually not more than four-five trophic levels (beyond this the energy available is negligible to support an organism). The trophic level interaction involves three concepts namely •Food Chain •Food Web •Ecological Pyramids
- 12. Food Chain •Anything which we eat to live is called food. •Food contains energy. •Food can be transferred from one organism to the other. •The process of transfer of food (energy) from one organism to a series of organisms is called as “food chain”. OR •Transfer of food energy from green plants (producers) through a series of organisms with repeated eating and being eaten link is called a food chain. E.g. Grasses → Grasshopper → Frog → Snake → Hawk/Eagle. •Each step in the food chain is called trophic level. •A food chain starts with producers and ends with top carnivores. •Basically, food chain is a mode, through which energy and materials (nutrients) move within an ecosystem. It displays how each member of a particular ecosystem obtains its food.
- 13. Types of Food Chains: 1) Grazing food chain and 2) Detritus food chain Grazing food chain The grazing food chain is a type of food chain that begins from the green plants and progresses via herbivores. Green plants or producers obtain food through a process of photosynthesis. The producers are directly dependent on the flow of solar energy. Energy is constantly added to the ecosystem through the grazing food chain. In the grazing food chain, energy is produced by the producers which are then transferred to the primary consumers, secondary consumers , and then to the tertiary consumers. For example, in a terrestrial ecosystem: Grassland ecosystem: the grass -- caterpillar -- lizard -- snake. Forest ecosystem: Grass -- Deer – Tiger Dessert ecosystem: Cactus – Mice – Scorpian -- Rattlesnake In aquatic ecosystem, Food chain in a pond phytoplankton -- zooplanktons -- small fishes – large fishes -- man Marine Food chain: Sea Weeds -- Small fish -- Large fish -- Sharks and other animals
- 15. Detritus food chain The detritus food chain is a type of food chain that begins from dead organic matter called detritus. The decomposers act on the dead matter and break it down into simple and inorganic substances. The food energy is transferred to the decomposers and detritivores, which are then eaten by predators. Here, the primary consumers that act on detritus are fungus, bacteria, and protozoans and they are also known as decomposers. The secondary consumers that feed on bacteria and fungi are called detritivores and it includes earthworms. The tertiary consumers are those organisms that act as predators and feed on earthworms including sparrows. In an aquatic ecosystem, the grazing food chain is the major conduit for energy flow. As against this, in a terrestrial ecosystem, a much larger fraction of energy flows through the detritus food chain than through the grazing food chain.
- 16. Importance of Food Chain a) The food chain helps maintain a balance in nature. b) It shows how every living thing relies on other living things for energy and survival. c) If one part of the food chain is disrupted, it can affect the entire ecosystem. d) A food chain describes the method in which a particular organism collects its food.
- 17. Food Web •Web means “network” such as spider’s web, World Wide Web (WWW) etc. •So, food web is a network of food chains. •Multiple interlinked food chains make a food web. •Food web represents all the possible paths of energy flow in an ecosystem. •If any of the intermediate food chains is removed, the succeeding links of the chain will be affected largely. •The food web provides more than one alternative for food to most of the organisms in an ecosystem and therefore increases their chance of survival.
- 24. •Depending upon the type of ecosystem, we have three types of pyramid of numbers. 1.Upright pyramid of numbers. 2.Partly upright pyramid of numbers. 3.Inverted pyramid of numbers. •Upright Pyramid of numbers: The number of individual organisms gradually decreases from lower tropic level to higher tropic level is called “upright pyramid of numbers”. Example: A grassland ecosystem and a pond ecosystem show an upright pyramid of numbers. Partially Upright Pyramid Of Numbers: A forest eco system is an example of partially upright pyramid. In a forest eco system, big trees are the producers, which are less number. So, these producers occupy the lower tropic level which is narrow base. Since the number of birds, insects and other species are higher when compared to the trees. fox, snakes, lizards, which occupy the third tropic level. Since the number of fox, snakes are lower when compared to the birds, insects. the number of lion, tiger are lower when compared to the fox and snakes. The number of individual organisms gradually increases from lower tropic level to higher tropic level, is known as “inverted pyramid of numbers”. Example: Parasitic food chain shows as inverted pyramid of number as shown in the following figure.
- 27. 1.It is expressed in gram per unit area. 2.Depending upon the type of ecosystem, we have two types of pyramid of biomass. •Upright pyramid of biomass. •Inverted pyramid of biomass. Upright Pyramid Of Biomass: The pyramid of biomass gradually decreases from the produce level (or) first tropic level to consumer level (higher tropic level) is called “upright pyramid of biomass” A forest ecosystem showed an upright pyramid of biomass. In this ecosystem, the biomass decreases from the producer level to consumer levels (as shown in figure) Inverted pyramid of biomass: The pyramid of biomass gradually increases from producer level to consumer level are called as Inverted pyramid of biomass. Example: The pond ecosystem shows an inverted pyramid of biomass. In this, ecosystem, the biomass increases from producer level to consumer levels as shown in the following figure.
- 30. It is expressed in calories per unit area per year. In an eco system, the energy flows from producer level to the consumer level. At each successive tropic level, there is a huge loss of energy (about 90%) in the form of heat, respiration, etc. Thus, at each next higher level only 10% of the energy passes on. Hence, there is a sharp decrease in energy at each and every producer to omnivores (or) top carnivores. Therefore, the pyramid of energy is always upright.