2.-Ecosystem-Food-Chain-and-Food-Web.ppt
- 2. The Ecosystem consists of the Biotic (biological) and Abiotic (physical) All ecosystems have three basic components: 1. Autotrophs or producers- are organisms that can synthesize their own foodstuffs. Major producers are algae and plants that absorb sunlight and use its energy to synthesize organic foodstuffs from water and carbon dioxide through photosynthesis. 2. Heterotrophs or consumers- are organisms that require a supply of organic matter or food from the environment; they typically ‘must eat’ other organisms to survive. a. organisms that consume plant tissue are called herbivores.
- 3. b. Organisms that consume animal tissue are called carnivores. c. Organisms that consume a combination of plant and animal tissues are called omnivores. d. Organisms that consume largely dead or decaying material and convert into inorganic substances are called decomposers or saprophytes. e. Organisms that live in association with and at the expense of other organisms from which they obtain organic nutrition are called parasites.
- 4. 3. Nonliving matter or the abiotic components- include : -energy (sunlight) -physical factors (such as temperature, light and humidity); and -chemical factors, both inorganic ions (for example, iron, magnesium, sodium, chlorine) and organic molecules (protein, carbohydrates, lipids, and nucleic acids).
- 5. Laws of Thermodynamics First Law of Thermodynamics- energy is neither created nor destroyed. It may change form, pass from one place to another, or act upon matter in various ways. Regardless of what transfers and transformations take place, however, no gain or loss in total energy occurs. Energy is simply transferred from one form or place to another. Ex. When wood burns, the potential energy lost from the molecular bonds of the wood equals the kinetic energy released as heat. When energy is lost from the system into the surrounding environment, the reaction is exothermic.
- 6. Second Law of Thermodynamics When energy is transferred or transformed, part of the energy assumes a form that cannot pass on any further. Entropy increases. (Entropy means transformation of matter and energy to a more random, more disorganized state). Ex. When coal is burned in a boiler to produce steam, some of the energy creates steam, and part is dispersed as heat to the surrounding air.
- 7. The same thing happens to energy in the ecosystem. As energy is transferred from one organism to another in the form of food, a large part of that energy is degraded as heat- is no longer transferable. The remainder is stored as living tissue.
- 8. Energy Flow BIOMASS, PRODUCTIVITY, AND PRODUCTION 1. The sun bombards the earth with solar radiation in two forms important to the biosphere. a. one important form of energy is heat, which warms the earth, drives the water cycle, and generates the water ad air currents of the atmosphere and the oceans.
- 9. b. The other is that portion of the solar radiation spectrum used in photosynthesis to produce carbohydrates and other compounds important to organisms 2. The flow of energy through an ecosystem begins with photosynthesis and continues as one group of organisms consumes another.
- 10. 3. The amount of energy accumulated by an organism is referred to as production. The rate of production is referred to as productivity. 4. As organisms accumulate energy, they usually convert it to tissue; this accumulated tissue is referred to a biomass.
- 11. BIOMASS The tissue of organisms that accumulates over time is known as biomass, or the total weight of living tissue At any one time, each group of organisms contains some amount of energy stored as biomass – termed the standing crop. Biomass usually is measured as grams of dry weight of organic matter per unit area, typically per square meter (g/m2). Biomass is an important parameter to measure because it indicates how much of an organism is present. It can reveal if organism is increasing or decreasing.
- 12. PRIMARY PRODUCTION The energy accumulated by photosynthetic plants and is the first and most basic form of energy storage in an ecosystem. Primary production of ecosystems is influenced by temperature and precipitation because it is based on photosynthesis, which is influenced by these environmental factors.
- 13. Forms of Primary Production a. Gross primary production – measure of the total of all the sun’s energy that is assimilated; therefore, GPP is equivalent to total photosynthesis. b. Net Primary Production-energy remaining as stored organic matter after energy for reproduction and maintenance is deducted.
- 14. Secondary Production 1. The accumulation of energy by consumer organisms (animals and decomposers such as bacteria and fungi) 2. The conversion of primary production to secondary production first occurs when plant tissue is consumed by herbivores. 3. The quantity of net production harvested by herbivores is influenced by the type of herbivore population.
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- 18. Food Web set of interconnected food chains by which energy and materials circulate within an ecosystem. Divided into two broad categories: 1.grazing web - which typically begins with green plants, algae, or photosynthesizing plankton 2.detrital web - which begins with organic debris.
- 19. These webs are made up of individual food chains: In a grazing web, materials typically pass from plants to plant eaters (herbivores) to flesh eaters (carnivores). In a detrital web, materials pass from plant and animal matter to bacteria and fungi (decomposers), then to detrital feeders (detritivores), then to their predators (carnivores).
- 20. Food chain - feeding relationships among organisms: movement of energy and nutrients from one feeding group of organisms to another in a series that begins with plants and ends with carnivores, detrital feeders and decomposers. Ex: grasshoppers eat grass, clay – colored sparrows eat grasshoppers, and marsh hawks prey upon the sparrows. Grass → grasshopper → sparrow → marsh hawk
- 21. Food chain components 1. Organisms in an ecosystem can be categorized as either producers (plants) or consumers. 2. Consumers generally are classified as herbivores, carnivores, omnivores, or decomposers; other feeding groups include parasites and scavengers (herbivores and carnivores that eat only dead material) 3. Primary producers form the basis for all food chains and food webs, because photosynthetic plants capture light.
- 22. 4. As one group of organisms consumes the next, energy passes along the food chain; each group of organism can be considered a temporary stopping point for the energy of the ecosystem. 5. The levels of food chain consist of various groups of organisms (for example, herbivores, carnivores, decomposers) and are referred to as trophic levels, or feeding levels.
- 23. Two major food chains: Net primary production Herbivores Carnivores Grazing Food Chain Detritus Decomposer herbivores Carnivores Detrital Food Chain
- 24. In any ecosystem, there are two major food chains: detrital and grazing The detrital food chain is the dominant food chain of most terrestrial and shallow water ecosystems; as such, it is the major pathway of energy flow in these systems. a. In ecosystems where the detrital food chain predominates, little of the net productivity is consumed by grazing herbivores, ad the bulk of the net production is utilized by detritivores, which feed on partly decomposed plant and animal tissue.
- 25. The grazing food chain is conspicuous and obvious in terrestrial ecosystems; it consists of herbivores (for example, cattle, rabbits, insects, gazelles, deer) consuming primary production.
- 26. The distinction for these two food chains is the source of energy for the first – level consumers, the herbivores. In the grazing food chain the source of energy is living plant biomass or net primary production (NPP). In the detrital food chain the source of energy is dead organic matter or detritus. In turn, the herbivores in each food chain are the source of energy from the carnivores and, so on.
- 27. Predator - carnivorous animal or destructive organism: a carnivorous animal that hunts, kills, and eats other animals in order to survive, or any other organism that behaves in a similar manner. Prey - animal hunted by other animals: an animal or animals caught, killed, and eaten by another animal as food.
- 28. TROPHIC LEVELS: The food web can be viewed not only as a network of chains but also as a series of trophic (nutritional) levels. Trophic Level Where It Gets Food 1st Trophic Level: Producer Makes its own food 2nd Trophic Level: Primary Consumer Consumes producers 3rd Trophic Level: Secondary Consumer Consumes primary consumers 4th Trophic Level: Tertiary Consumer Consumes secondary consumers
- 29. first trophic level - Green plants their source of energy is the sun and their nutrients come from soil, water and atmosphere.
- 30. second trophic level - Herbivores (plant eaters) - they make up the first level consumers. - herbivores are capable of converting energy stored as plant tissue into animal tissue. - without them, the higher trophic levels could not exist because only herbivores can live on a high – cellulose diet. - energy source for carnivores.
- 31. third trophic level – Carnivores (predators feeding upon the herbivores) - the typical carnivore is adapted for a diet of flesh. Omnivores, consumers of both plants and animals, belong to the second and third. fourth trophic level - Secondary carnivores (which are predators that feed on predators)
- 32. As the trophic levels rise, the predators become fewer, larger, fiercer, and more agile. Scavengers – are animals that eat dead plant and animal material. ex: termites and various beetles that feed on dead and decaying wood clams and other marine invertebrates that feed on plant particles in the water.
- 33. vultures, gulls, and hyenas – feed on animal remains. Scavengers are either herbivores or carnivores Saprophytes – plant counterpart of scavengers. - draw their nourishment from dead plant and animal material chiefly plants. - because they do not require sunlight as an energy source, they can live in deep shade or dark caves. ex: fungi
- 34. At the second and higher levels, decomposers of the available materials function as herbivores or carnivores depending on whether their food is plant or animal material.
- 35. Through these series of steps of eating and being eaten, energy flows from one trophic level to another. Green plants or other photosynthesizing organisms use light energy from the sun to manufacture carbohydrates for their own needs. Most of this chemical energy is processed in metabolism and dissipated as heat in respiration.
- 36. Plants convert the remaining energy to biomass, both above ground as woody and herbaceous tissue and below ground as roots. Ultimately, this material, which is stored energy, is transferred to the second trophic level, which comprises grazing herbivores, decomposers, and detrital feeders. Most of the energy assimilated at the second trophic level is again lost as heat in respiration; a fraction becomes new biomass.
- 37. Organisms in each trophic level pass on as biomass much less energy than they receive. Thus, the more steps between producer and final consumer, the less energy remains available. Seldom are there more than four links, or five levels, in a food web. Eventually, all energy flowing through the trophic levels is dissipated as heat. The process whereby energy loses its capacity to do work is called entropy.
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