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Ecosystem powerpoint 1
- 2. • 2.1 Structure of Eco System 5/1/2013 AUTHOR-GURU IB/ESS 2
- 3. What is Organism ? Organism : • An organism is a fundamental functional unit in ecology because it interacts directly with the environment as well as with other organism e.g., Rabbits 5/1/2013 AUTHOR-GURU IB/ESS 3
- 5. What is Population? • It refers to the organism of the same species that are in proximity to one another • e.g., A group of rabbit 5/1/2013 AUTHOR-GURU IB/ESS 5
- 7. What is Community? • This includes all the populations occupying a given area. • The size of the community depends on our scale of reference • The community and the non-living environment together are referred to as an ECOLOGICAL SYSTEM or ECOSYSTEM • e.g., pond fish and plants 5/1/2013 AUTHOR-GURU IB/ESS 7
- 10. What is species? • A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. 5/1/2013 AUTHOR-GURU IB/ESS 10
- 11. • What is habitat? area that A habitat is an ecological or environmental is inhabited by particular species of animal, plant or other type of organism. • It is the natural environment in which an organism lives, or the physical environment that surrounds a species population. 5/1/2013 AUTHOR-GURU IB/ESS 11
- 13. What is species? • In biology, a species is one of the basic units of biological classification . • A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. 5/1/2013 AUTHOR-GURU IB/ESS 13
- 14. What is habitat? • A habitat is an ecological or environmental area that is inhabited by particular species of animal, plant or other type of organism. • It is the natural environment in which an organism lives, or the physical environment that surrounds a species population. 5/1/2013 AUTHOR-GURU IB/ESS 14
- 16. Experts release list of world's 100 most threatened species • Seoul, Sept. 11 : International conservation group has identified a list of the earth's most threatened 100 animals, plants and fungi and have called for an urgent need to protect them. • The species have been identified by more than 8,000 scientists from the IUCN Species Survival Commission (IUCN SSC), but they fear they will be allowed to die because none of these species provide humans with any benefits. 5/1/2013 AUTHOR-GURU IB/ESS 16
- 18. • An ecosystem has two basic components • ABIOTIC COMPONENTS • BIOTIC COMPONENTS 5/1/2013 AUTHOR-GURU IB/ESS 18
- 19. • • • • Biotic Components Biotic components is classified into three categories: PRODUCERS-Autotrophic CONSUMERS -Heterotrophic DECOMPOSERS OR SAPTROTROPHS 5/1/2013 AUTHOR-GURU IB/ESS 19
- 21. • Producers are things such as plants that are fed off of but do not eat other producers or organisms. • Consumers are organisms (including us humans) that get their energy from producers, regarding the flow of energy through an ecosystem 5/1/2013 AUTHOR-GURU IB/ESS 21
- 23. • A decomposer is an organism of decay. • These are also called saprobes. • They break down the remains of dead animals and plants, releasing the substances that can be used by other members of the ecosystem 5/1/2013 AUTHOR-GURU IB/ESS 23
- 27. What is Abiotic components? • The non living ,physical and chemical components of an ecosystem are called the abiotic factors and include: • Light • Temperature, • Water, • Soil • The atmosphere • Climate –Light intensity, temperature range, precipitation 5/1/2013 AUTHOR-GURU IB/ESS 27
- 29. What is NICHE? • In ecology, a niche is a term describing the way of life of a species. • Each species is thought to have a separate, unique niche. • The ecological niche describes how an organism or population responds to the distribution of resources and competitors 5/1/2013 AUTHOR-GURU IB/ESS 29
- 30. Example for NICHE • One example is squirrels that collect acorns and bury them for winter. • Another is honeybees that gather nectar from flowers to make honey. • Other organisms that may exist in the same environment don't do this. • For instance, a bird may live in the same tree as a beehive, but the bird does not make honey the way the bees do. That is not its niche. 5/1/2013 AUTHOR-GURU IB/ESS 30
- 31. What is Eco System? • A dynamic complex of plants, animals and micro organisms inhabiting a particular area with their non living environment interacting as a functional unit 5/1/2013 AUTHOR-GURU IB/ESS 31
- 32. Sir Arthur George Tansley (15 August 1871 - 25 November 1955) was an English botanist who was a pioneer in the science of ecology 5/1/2013 AUTHOR-GURU IB/ESS 32
- 33. 2.1.3 Identify and explain trophic levels in food chains and food webs selected from the local environment. 5/1/2013 AUTHOR-GURU IB/ESS 33
- 34. What is Trophic levels? • Trophic levels are the feeding position in a food chain such as primary producers, herbivore, primary carnivore, etc. • Green plants form the first trophic level, the producers. • Herbivores form the second trophic level, while carnivores form the third and even the fourth trophic levels. 5/1/2013 AUTHOR-GURU IB/ESS 34
- 37. What is Food chain? • The feeding of one organism upon another in a sequence of food transfers is known as a food chain. • Food chain is the chain of transfer of energy from one organism to another. A simple food chain is like the following: • rose plant -- aphids -- beetle -- chameleon -hawk. 5/1/2013 AUTHOR-GURU IB/ESS 37
- 46. What is food web? • In an ecosystem there are many different food chains and many of these are cross-linked to form a food web. • Ultimately all plants and animals in an ecosystem are part of this complex food web. 5/1/2013 AUTHOR-GURU IB/ESS 46
- 54. "Zooplankton" refers to small aquatic animals. 5/1/2013 AUTHOR-GURU IB/ESS 54
- 57. 2.1.4 Explain the principles of pyramids of numbers, pyramids of biomass, and pyramids of productivity, and construct such pyramids from given data. 5/1/2013 AUTHOR-GURU IB/ESS 57
- 58. What is Ecological Pyramids? Trophic levels and the energy flow from one level to the next, can be graphically depicted using an ecological pyramid. Three types of ecological pyramids can usually be distinguished namely: 1. Pyramids of numbers 2. Pyramid of biomass 3. Pyramids of productivity 5/1/2013 AUTHOR-GURU IB/ESS 58
- 59. Pyramids of numbers • A pyramid of numbers is a graphical representation of the numbers of individuals in each population in a food chain. • A pyramid of numbers can be used to examine how the population of a certain species affects another 5/1/2013 AUTHOR-GURU IB/ESS 59
- 61. PYRAMID OF NUMBERS represents storages found at each trophic level. Units vary 5/1/2013 AUTHOR-GURU IB/ESS 61
- 65. Grassland (summer) Temperate Forest (summer) Tertiary consumers Secondary consumers Primary consumers Producers A few large producers (the trees) support a much larger number of Small primary consumers (insects) that feed on the trees. 5/1/2013 AUTHOR-GURU IB/ESS 65
- 66. Pyramids of Numbers Advantages • Overcomes the problems of pyramids of number. Disadvantages • Only uses samples from populations, so it is impossible to measure biomass exactly. also the time of the year that biomass is measured affects the result. 5/1/2013 AUTHOR-GURU IB/ESS 66
- 67. Jayanthi Natarajan Minister for Environment and Forests 5/1/2013 AUTHOR-GURU IB/ESS 67
- 68. Pyramid of biomass • The total amount of living or organic matter in an ecosystem at any time is called 'Biomass’. • Pyramid of biomass is the graphic representation of biomass present per unit area of different tropic levels, with producers at the base and top carnivores at the tip". 5/1/2013 AUTHOR-GURU IB/ESS 68
- 69. • Represents the standing stock of each trophic level (in grams of biomass per unit area g / m2) • Represent storages along with pyramids of numbers 5/1/2013 AUTHOR-GURU IB/ESS 69
- 70. PYRAMID OF BIOMASS represent the standing stock at each trophic level. Units: J m-2 or g m-2 5/1/2013 AUTHOR-GURU IB/ESS 70
- 73. Abandoned Field Ocean Tertiary consumers Secondary consumers Primary consumers Producers In open waters of aquatic ecosystems, the biomass primary consumers (zooplankton) can exceed that of producers. The zooplankton eat the Producers (phytoplankton) as fast as they reproduce, so their population is never very large. 5/1/2013 AUTHOR-GURU IB/ESS 73
- 74. How do we get the biomass of a trophic level to make these pyramids? • • • • Take quantitative samples – known area or volume Measure the whole habitat size Dry samples to remove water weight Take Dry mass for sample then extrapolate to entire trophic level • Evaluation It is an estimate based on assumption that – all individuals at that trophic level are the same – The sample accurately represents the whole habitat 5/1/2013 AUTHOR-GURU IB/ESS 74
- 77. • Analysis of various ecosystems indicates that those with squat biomass pyramids are less likely to be disrupted by physical or biotic changes than those with tall, skinny pyramids (having conversion efficiencies less than 10%). 5/1/2013 AUTHOR-GURU IB/ESS 77
- 78. Measurement of biomass of different trophic levels in an ecosystem. 5/1/2013 AUTHOR-GURU IB/ESS 78
- 79. Describe one method for the measurement of biomass of different trophic levels in an ecosytem. • Representative samples of all living organisms in the ecosystem are collected, for example from randomly positioned quadrats. • The organisms are dried, by being placed in an oven at 60-80 C. • The mass of organisms in each trophic level is measured using an electronic balance. 5/1/2013 AUTHOR-GURU IB/ESS 79
- 80. Multiply the mean height by the stem density 5/1/2013 AUTHOR-GURU IB/ESS 80
- 81. • Biomass can be assessed indirectly and completely non destructively by • Counting the number of individuals of the target speices • Randomly selecting a sample of individuals • Determining mean height within the sample (height will be an indirect measure of biomass) • Multiply the mean height by the stem density (number of individuals) 5/1/2013 AUTHOR-GURU IB/ESS 81
- 82. • A more destructive method involves taking a sample of individuals of the target species and cutting them at soil level. • Tag each individual with a label, dry it to a stable weight and weigh it. • Determine the mean mass of the plants in the area and multiply by the stem density in the area. 5/1/2013 AUTHOR-GURU IB/ESS 82
- 84. IDENTIFY THE ENDANGERED ANIMAL 5/1/2013 AUTHOR-GURU IB/ESS 84
- 86. Pyramids of Productivity • A graphical representation in the shape of a pyramid showing the distribution of productivity or flow of energy through the tropic levels. 5/1/2013 AUTHOR-GURU IB/ESS 86
- 87. 10 J m-2 yr-1 100 J m-2 yr-1 1,000 J m-2 yr-1 10,000 J m-2 yr-1 producers 5/1/2013 AUTHOR-GURU IB/ESS 87
- 89. PYRAMID OF PRODUCTIVITY represents the flow of energy through each trophic level. Units: J m-2 yr-1 or g m-2 yr-1 5/1/2013 AUTHOR-GURU IB/ESS 89
- 90. Pyramids of productivity • Flow of energy through trophic levels • Energy decreases along the food chain – Lost as heat • Productivity pyramids ALWAYS decrease as they go higher – 1st and 2nd laws of thermodynamics • Shows rate at which stock is generated at each level • Productivity measured in units of flow (J / m2 yr or g / m2 yr ) Joule per square metre in year/ 5/1/2013 AUTHOR-GURU IB/ESS 90
- 91. • As you move up each trophic level, only 10% of the energy is transferred. • The other 90% is used for everyday life functions, metabolism. 5/1/2013 AUTHOR-GURU IB/ESS 91
- 93. Pyramid structure affects the functioning of an ecosystem. Bioaccumulation 5/1/2013 AUTHOR-GURU IB/ESS 93
- 95. Pyramids of productivity • Advantages • Most accurate system shows the actual energy transferred and allows for rate of production. • Disadvantages • It is very difficult and complex to collect energy data. 5/1/2013 AUTHOR-GURU IB/ESS 95
- 96. PYRAMID OF STANDING CROP • Pyramid diagrams may show the fixed quantity of number, biomass or energy that exists at a particular time in a given area or averaged from many of these measurements. • This is termed STANDING CROP. • The unit would be number,dry biomass or energy kg/m2 or J/m3. 5/1/2013 AUTHOR-GURU IB/ESS 96
- 97. Figure 54.14 Food energy available to the human population at different trophic levels Efficiency of trophic levels in relation to the total energy available decreases with higher numbers But efficiency of transfer always remains around that 10% rule 5/1/2013 AUTHOR-GURU IB/ESS 97
- 98. • ENERGY FLOW THROUGH • PRODUCERS • CONSUMERS • DECOMPOSERS 5/1/2013 AUTHOR-GURU IB/ESS 98
- 99. Energy Flow through Producers • Producers convert light energy into chemical energy of organic molecules • Energy lost as cell respiration in producers then as heat elsewhere • When consumers eat producers energy passes on to them • In death organic matter passes to saprophytes & detritivores 5/1/2013 AUTHOR-GURU IB/ESS 99
- 100. Energy Flow through Consumers • • • Obtain energy by eating producers or other consumers Energy transfer never above 20% efficient, usually between 10 – 20% Food ingested has multiple fates 1. Large portion used in cell respiration for meeting energy requirements (LOSS) 2. Smaller portion is assimilated used for growth, repair, reproduction 3. Smallest portion, undigested material excreted as waste (LOSS) AUTHOR-GURU 5/1/2013 IB/ESS 100
- 101. Figure 54.10 Energy partitioning within a link of the food chain 5/1/2013 AUTHOR-GURU IB/ESS 101
- 102. Energy flow through Decomposers • Some food is not digested by consumers so lost as feces to detritivores & saprophytes • Energy eventually released by process of cell respiration or lost as heat 5/1/2013 AUTHOR-GURU IB/ESS 102
- 103. 2.1.5 Discuss how the pyramid structure affects the functioning of an ecosystem. 5/1/2013 AUTHOR-GURU IB/ESS 103
- 104. How does pyramid structure effect ecosystem function? 1. Limited length of food chains • • • Rarely more than 4 or 5 trophic levels Not enough energy left after 4-5 transfers to support organisms feeding high up Possible exception marine/aquatic systems b/c first few levels small and little structure 2. Vulnerability of top carnivores • • • 5/1/2013 Effected by changes at all lower levels Small numbers to begin with Effected by pollutants & toxins passed through system AUTHOR-GURU IB/ESS 104
- 105. What is Biomagnification? • Biomagnification is the sequence of processes in an ecosystem by which higher concentrations of a particular chemical, such as the pesticide DDT, are reached in organisms higher up the food chain, generally through a series of prey-predator relationships. 5/1/2013 AUTHOR-GURU IB/ESS 105
- 108. What is bioaccumulation? • Bioaccumulation refers to the accumulation of substances, such as pesticides, or other organic chemicals in an organism. • Bioaccumulation occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost. 5/1/2013 AUTHOR-GURU IB/ESS 108
- 112. IDENTIFY THE ENDANGERED ANIMAL 5/1/2013 AUTHOR-GURU IB/ESS 112
- 114. • According to the Hindu mythology blackbuck or Krishna Jinka is considered as the vehicle (vahana) of the Moon-god Chandrama. 5/1/2013 Akbar Hunting Black BuckAkbarnama AUTHOR-GURU IB/ESS 114
- 116. Predation • In ecology, predation describes a biological interaction where a predator feeds on its prey. • Examples :Lion killing buffalo, Eagle killing Rabbit, Mantis eating a bee. 5/1/2013 AUTHOR-GURU IB/ESS 116
- 119. Herbivore • Herbivores are organisms that are adapted to eat plants. • Herbivory is a form of predation in which an organism consumes principally autotrophs such as plants, algae and photosynthesizing bacteria. 5/1/2013 AUTHOR-GURU IB/ESS 119
- 121. Parasitism • Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the host. Example : • Mosquito: Females ingest blood for the protein. Male mosquitos ingest plant juices. • Heartworm of dogs, whose adults reside in the right side of the heart 5/1/2013 AUTHOR-GURU IB/ESS 121
- 122. Mosquito: Females ingest blood for the protein. Male mosquitos ingest plant juices 5/1/2013 AUTHOR-GURU IB/ESS 122
- 123. Heartworm of dogs, whose adults reside in the right side of the heart 5/1/2013 AUTHOR-GURU IB/ESS 123
- 124. Mutualism • Mutualism is a biological interaction that is beneficial to both parties. • Mutualism is the way two organisms biologically interact where each individual derives a fitness benefit (i.e. increased survivorship). • Examples :Clownfish and sea anemones, langur monkey curing cow's ear 5/1/2013 AUTHOR-GURU IB/ESS 124
- 127. 2.3.5 APPLY SIMPSON’S DIVERSITY INDEX AND OUTLINE ITS SIGNIFICANCE Simpson’s Diversity Index 5/1/2013 AUTHOR-GURU IB/ESS 127
- 128. Simpson’s Diversity Index 1) Simpson's diversity index (also known as species diversity index) is one of a number of diversity indices, used to measure diversity. 2) In ecology, it is often used to quantify the biodiversity of a habitat. 3) It takes into account the number of species present, as well as the relative abundance of each species. 4) The Simpson index represents the probability that two randomly selected individuals in the habitat will not belong to the same species. 5/1/2013 AUTHOR-GURU IB/ESS 128
- 129. • For plant species the percentage cover in a square is usually used; • For animal species, for example in a river, the number of organisms of a species is used. • The reason percentage cover is used is because it is usually very difficult to count all the individual plants 5/1/2013 AUTHOR-GURU IB/ESS 129
- 130. Simpson’s Diversity Index • Where: • D = diversity index N = total number of organisms of all species found n = number of individuals of a particular species 5/1/2013 AUTHOR-GURU IB/ESS 130
- 131. Species Number of individuals in Number of individuals in Ecosystem 1 Ecosystem 2 A 23 2 B 28 2 C 22 1 D 27 93 Total individuals in ecosystem 100 98 5/1/2013 AUTHOR-GURU IB/ESS 131
- 132. Simpson’s Diversity Index = 100 x (100 – 1) [23x(23-1)] + [28x(28-1)] + [22x(22-1)] + [27x(27-1)] = 4.08 For Ecosystem 2: Simpson’s Diversity Index = 98 x (98 – 1) [2x(2-1)] + [2x(2-1)] + [1x(1-1)] + [93x(93-1)] = 1.11 5/1/2013 AUTHOR-GURU IB/ESS 132
- 133. RESULT • From this it can be seen that ecosystem 1 has the highest index of diversity. • The larger then Simpson’s index the more diverse. • Increasing diversity tends to suggest more stable ecosystems with more connections within them. 5/1/2013 AUTHOR-GURU IB/ESS 133
- 134. 2.2.2 Abiotic factors in Marine Ecosystems Describe and evaluate methods for measuring at least three abiotic (physical) factors within an ecosystem. 5/1/2013 AUTHOR-GURU IB/ESS 134
- 136. What are Limiting Factors of an ecosystem? • Limiting factors are physical or biological necessities whose presence or absence in inappropriate amounts limits the normal action of the organism. 5/1/2013 AUTHOR-GURU IB/ESS 136
- 137. Limiting factor fro Marine Ecosytem • • • • • Light Temperature Salinity Dissolved Gases Pressure 5/1/2013 AUTHOR-GURU IB/ESS 137
- 138. Light is needed for photosynthesis and vision. • Blue light penetrates deepest. 5/1/2013 AUTHOR-GURU IB/ESS 138
- 139. Temperature influences the metabolic rate, the rate at which reactions proceed within an organism. 5/1/2013 AUTHOR-GURU IB/ESS 139
- 140. What is the Deepest Part of the Ocean? • The ocean's deepest area is the CHALLENGER DEEP (also called the Marianas Trench), which is about 11 km (almost 7 miles, or almost 36,000 feet) deep. • The trench is 1,554 miles long and 44 miles wide, 5/1/2013 AUTHOR-GURU IB/ESS 140
- 142. • Most marine organisms are ECTOTHERMIC having an internal temperature that stays very close to that of their surroundings. • A few complex animals (mammals & birds) are ENDOTHERMIC, meaning they maintain a stable internal temperature. • Ocean temperature varies in both depth and latitude. • Ocean temperatures vary less than on land. 5/1/2013 AUTHOR-GURU IB/ESS 142
- 143. Salinity greatly affect cell membranes and protein structure. • Disrupts cells osmotic pressure. • Varies because of rainfall, evaporation and runoff from land. 5/1/2013 AUTHOR-GURU IB/ESS 143
- 144. How deep is the ocean? The average depth of the ocean is about 4,267 meters (14,000 feet). The deepest part of the ocean is called the Challenger Deep and is located beneath the western Pacific Ocean in the southern end of the Mariana Trench, which runs several hundred kilometers southwest of the U.S. territorial island of Guam. Challenger Deep is approximately 11,030 meters (36,200 feet) deep. 5/1/2013 AUTHOR-GURU IB/ESS 144
- 147. GASES Dissolved Gases are necessary for photosynthesis and respiration. • CO2 dissolves more easily in water than O2. • CO2 is more abundant in deep waters than surface water. • O2 decrease dramatically where light penetration decreases. 5/1/2013 AUTHOR-GURU IB/ESS 147
- 148. How deep can humans go underwater? • Breathing air, humans can go down around 350 feet without any sort of protection from pressure • Utilizing mixed gases, a diver can reach a little over 300 meters 5/1/2013 AUTHOR-GURU IB/ESS 148
- 149. Pressure from the layers of water above. • Increases with increasing depth. • To counteract the mass of heavy muscles and bone, many swimming fishes have gas-filled bladders. • Deep-sea fish don’t have gas bladders, but light bones and oily watery flesh. 5/1/2013 AUTHOR-GURU IB/ESS 149
- 151. Marine Zones • Areas of homogeneous physical features. • Usually based on light, temperature, salinity, depth, latitude, behavior and/or water density. 5/1/2013 AUTHOR-GURU IB/ESS 151
- 154. By light • Upper zone is called the Euphotic zone and is where the rate of photosynthesis is high. • Lower zone is called Disphotic zone and is where organisms can see, but there is sufficient light for photosynthesis. Aphotic zone where no light penetrates. 5/1/2013 AUTHOR-GURU IB/ESS 154
- 155. By Location Pelagic zone between water and ocean bottom. a. Neritic zone = near shore over the continental shelf 5/1/2013 AUTHOR-GURU IB/ESS 155
- 156. b. Oceanic zone = deep-water beyond the continental shelf. i. Epipelagic = photic zone of the ocean. ii. Mesopelagic = middle ocean waters. iii. Bathypelagic = ocean floor. iv. Abyssopelagic = deep-ocean trenches. 5/1/2013 AUTHOR-GURU IB/ESS 156
- 162. MEASURING THE ABIOTIC FACTORS You should be able to describe & evaluate three methods in details with references to a named ecosystem 5/1/2013 AUTHOR-GURU IB/ESS 162
- 163. 1.TEMPERATURE:-Normally measured using thermometers or temperature probes attached to data logger. Seasonal & diurnal variations important ,as is the influence of aspect 5/1/2013 AUTHOR-GURU IB/ESS 163
- 164. 2.LIGHT INTENSITY: • This measured using a light meter in lux. • Seasonal,latitide influence incident the radiation 5/1/2013 AUTHOR-GURU IB/ESS 164
- 165. 3.SOIL: • Soil organic matter is assessed by baking in the oven at over 100 degrees to evaporate off the water and given as percentage of original soil mass 5/1/2013 AUTHOR-GURU IB/ESS 165
- 166. 4.WIND SPEED: • This is measured using an anemometer; an instrument with cuts that spin in the wind 5/1/2013 AUTHOR-GURU IB/ESS 166
- 167. 5.SALINITY: • This measured using refractometer by placing a droplet of sample water on a lens and allowing light to enter through the water 5/1/2013 AUTHOR-GURU IB/ESS 167
- 168. 6.PH: • This measured using universal indicator or a pH probe 7.Turbidity • Measured in depth(m) using a sechi disc(black& white decorated disc) lowered on a measuring rope until it is no longer visible 5/1/2013 AUTHOR-GURU IB/ESS 168
- 169. The Secchi disk measures the transparency of the water. Transparency can be affected by the color of the water, algae, and suspended sediments. Transparency decreases as color, suspended sediments, or algal abundance increases. 5/1/2013 AUTHOR-GURU IB/ESS 169
- 170. SPECIES IDENTIFICATION • This is usually done with a published identification key. • The key asks a question and the answer determines what step to go to next, either the name of the species or another question 5/1/2013 AUTHOR-GURU IB/ESS 170
- 171. (presence/absence of legs; number of legs; presence/absence of tentacles; number of tentacles; shape; visible eyes; bristles 5/1/2013 AUTHOR-GURU IB/ESS 171
- 172. DIRECT METHODS OF ESTIMATING OF ABUNDANCE IN ANIMALS • Animals that don’t move quickly, such as rocky shore limpets or grassland snails, can be counted in quadrats giving a direct measure of population density. • This only suitable for species that don’t run away • A variety of direct sampling techniques can be used to collect invertebrates using nets and traps 5/1/2013 AUTHOR-GURU IB/ESS 172
- 173. 2.3.2 Abundance of organisms. 5/1/2013 AUTHOR-GURU IB/ESS 173
- 174. Methods for Estimating Population Size 1. Quadrats 2. Capture/Mark/Release/Recapture (Lincoln Index) 5/1/2013 AUTHOR-GURU IB/ESS 174
- 175. Why we should know the population size of an ecosystem? • Knowing population size is important in making environmental decisions that would affect the population. • Making a decision on an estimate that is too high extinction. • Making a decision on an estimate that is too low unnecessarily hurt people that depend on the animals for food & income. 5/1/2013 AUTHOR-GURU IB/ESS 175
- 176. • ESTIMATING THE POPULATION USING THE NETS 5/1/2013 AUTHOR-GURU IB/ESS 176
- 178. 1.Freshwater nets for lake and stream invertebrates 5/1/2013 AUTHOR-GURU IB/ESS 178
- 182. 2.Sweep nets for grassland and scrub Sweep nets are sturdy nets used to collect insects from long grass. 5/1/2013 AUTHOR-GURU IB/ESS 182
- 185. 4.Pit trapping and baited traps for terrestrial invertebrates 5/1/2013 AUTHOR-GURU IB/ESS 185
- 188. 5.Beating trays for invertebrates in trees 5/1/2013 AUTHOR-GURU IB/ESS 188
- 191. • When estimating population size it is important to collect RANDOM SAMPLES. • A sample is a part of a population, part of an area or part of some other whole thing, chosen to illustrate what the whole population, area or other thing is like. • In a random sample every individual in a population has an equal chance of being selected. 5/1/2013 AUTHOR-GURU IB/ESS 191
- 197. Using Quadrats 1. Mark out area to be sampled. 2. Place quadrates ( 1 m2, 10 m2) randomly within the area. 3. Count how many individuals are inside each of the quadrates. 4. Calculate the mean number of individuals per quadrate. 5. Pop. Size = mean x total area area of each Quadrat 5/1/2013 AUTHOR-GURU IB/ESS 197
- 198. SYSTEMATIC QUDRATS RANDOM QUDRATS Quadrat sampling is suitable for plants that do not move around and are easy to find. 5/1/2013 AUTHOR-GURU IB/ESS 198
- 199. Quadrat method can be used to determine: POPULATION DENSITY = number of individuals of each species per area. PERCENTAGE FREQUENCY = percent of each species found within an area. PERCENTAGE COVER = percent of plant covering a given area. 5/1/2013 AUTHOR-GURU IB/ESS 199
- 201. Capture/Mark/ Release/Recapture Lincoln index 1. Capture as many individuals as possible in the area occupied by the animal population, using netting, trapping or careful searching. 2. Mark each individual, without making them more visible to predators and without harming them. 5/1/2013 AUTHOR-GURU IB/ESS 201
- 202. 3. Release all the marked individuals and allow them to settle back into their habitat. 4. Recapture as many individuals as possible and count how many are marked and how many are unmarked. 10 marked 14 unmarked 5/1/2013 AUTHOR-GURU IB/ESS 202
- 204. Assumptions: 1. The population of organisms must be closed, with no immigration or emigration. 2. The time between samples must be very small compared to the life span of the organism being sampled. 3. The marked organisms must mix completely with the rest of the population during the time between the two samples. 4. Organisms are not hurt or disadvantaged by being caught and marked and therefore all organisms have an equal opportunity of being recaptured 5/1/2013 AUTHOR-GURU IB/ESS 204
- 205. 5. Calculate the estimated population size by using the Lincoln Index: population size = N1 X N2 N3 N1 = number caught and marked initially N2 = total number caught in 2nd sample N3 = number of marked individuals recaptured Most suitable for animals that move around and are difficult to find. 5/1/2013 AUTHOR-GURU IB/ESS 205
- 206. • Next unit is continuing in the another PowerPoint presentation 5/1/2013 AUTHOR-GURU IB/ESS 206