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6th Grade Ecosystem Dynamics 2015 11 10 www.njctl.org 2
Table of Contents: Ecosystem Dynamics Intro to Ecology Click on the topic to go to that section Ecological Interactions Population Dynamics Energy in Food Webs 3
Breaking It Down Lab What environmental factors affect the rate of decomposition? Make careful observations for the next 10 days. 4
Introduction to Ecology Return to Table of Contents 5
Ecology Ecology is the study of the interactions between organisms and their environment. This picture includes one squirrelfish (red), two cleaner wrasse (little blue striped fish) and some coral. What interactions can you observe in this picture? 6
Ecology The squirrelfish is being cleaned by the cleaner wrasse. The cleaner wrasse are being protected by the squirrelfish. All of the fish are being protected by the coral. Organisms are able to interact with living and nonliving aspects of their environment. 7
Levels of Organization Scientists often classify living things into different kinds of groups. In an ecosystem, classifications are known as levels of organization. Species Population Community Ecosystem Biome (smallest) Biosphere (largest) 8
Species Species is a group of organisms that share common characteristics. Individuals within a species are only able to breed with others from the same species. Examples of different species include the following: Panda Bald Eagle Blue Spruce Pandas cannot breed with eagles because they are different species. 9
Population A population is a group of the same species living in the same place, at the same time. Blue and gold snappers are found in the Pacific, from Mexico down to Ecuador. Although they are all the same species, a group of snappers that live off the coast of Ecuador is a different population than a group that live off the coast of Mexico. 10
Community A community is composed of all the different populations of species that live together in a given area. This deciduous forest community is composed of lots of different populations: trees deer fungus insects birds bears What are some ways that the organisms in this community interact with each other? 11
Ecosystem An ecosystem includes all of the living and nonliving factors that exist in a community. What living factors do you see in this ecosystem? What nonliving factors do you see in this ecosystem? 12
Factors Abiotic factors are physical, nonliving factors that shape an ecosystem. Temperature Wind Sunlight Precipitation Temperature Wind Soil type Nutrient availability Nutrients Soil 13
Factors Biotic factors are the living things that make up an ecosystem. Plants Animals Fungi Bacteria 14
Biome A biome is a set of ecosystems that share similar characteristics. Biomes are often defined by abiotic factors such as climate, geology, moisture, and soil type. This is the tundra, the world's coldest and driest biome. The average annual temperature is 28 C. It is very windy and receives about the same amount of precipitation as the desert. 15
Biome Answer Look at the map. How is a biome related to the climate of its area? 16
Biome There are also marine biomes. What type of marine biomes are located near you? Source: US Dept. of Agriculture Click here to watch a video of beautiful imagery of different biomes. 17
Biosphere All of the terrestrial and marine biomes blend into each other on Earth. The biosphere is the sum of all the ecosystems established on Earth. 18
1 Which is not a level of organization in an ecosystem? A Population B Neighborhood C Community Answer D All are levels of organization in an ecosystem 19
2 A chipmunk and a ground squirrel are two different species. This means that they cannot A live in the same area. B interact in any way. C breed. Answer D eat the same food. 20
3 There are many types of populations within a given community. True False Answer 21
4 Which is not true of ecosystems? A Ecosystems only contain living things. B Ecosystems contain both living and non living things. C Ecosystems are found on both land and in water. Answer D Ecosystems only contain several communities. 22
5 Which of the following is not an abiotic factor? A rocks B water C soil Answer D All are abiotic factors 23
6 Which is not a biotic factor? A people B plants C sunlight Answer D All are biotic factors 24
7 All biomes have similar climates. True False Answer 25
Stranded! Activity You are stranded in your biome! Conduct research and think carefully in order to determine what items you need in order to survive? 26
Ecological Interactions Return to Table of Contents 27
Ecological Interactions Organisms in an ecosystem interact with their surroundings in numerous ways. They can interact with both biotic and abiotic components. Remember this squirrelfish? List a biotic and abiotic interaction of the squirrelfish with its environment. Answer 28
Habitat The term habitat describes the specific area where an organism lives within an ecosystem. A habitat is like an organism's home within an ecosystem. An organism's habitat answers the question "Where do you live?". 29
Habitat This penguin's habitat is the ice shelves of Antarctica. The saguaro cactus's habitat is the desert of the southwestern US. 30
Niche An organism's niche is a description of the role it plays in its habitat. A niche includes all aspects of where and how an organism lives including: * the type of food it eats * how it obtains food * where it lives in its environment (tree, nest, hive, etc.) * when and how it reproduces 31
Niche An organism's niche answers the question "How do you make a living?". Komodo Dragon Niche Komodo dragons live in the Indonesian Islands. They hunt and ambush invertebrates, birds and mammals. They lay up to 20 eggs at a time in self dug holes. The eggs incubate for eight months. Komodo dragons take nine years to mature and can live up to 30 years. 32
8 The Venus flytrap lives in subtropical wetlands where the soil is low in nitrogen and phosphorus. This is a description of the Venus flytrap's A habitat. B niche. Answer 33
9 The Venus flytrap is a carnivorous plant that catures insects and arachnids that crawl on its leaves. Although they produce food via photosynthesis, their prey gives them nutrients that are lacking in their environment. They are perennial plants, meaning that they flower every year. This is a description of the Venus flytrap's A habitat. Answer B niche. 34
Needs of Organisms All organisms need certain things to survive. How many can you think of? Write your ideas below. 35
Organisms need... Food Water Shelter Air 36
Importance of the Environment Organisms are constantly interacting with biotic and abiotic factors in their ecosystems in order to obtain food, water, shelter and air. This beaver gets food by eating plant life. He gets water from the local river or stream by which he lives. He gets air from the surrounding atmosphere. He makes their own shelter by building a den out of wood. Answer In what ways does this beaver interact with biotic factors in the environment? How about abiotic factors? 37
Ecological Interactions Every organism in an ecosystem survives by obtaining their needs from the environment. The act of obtaining these needs leads to different types of interactions within an ecosystem. Competition Predator/prey Mutually beneficial Clownfish receive shelter from the anemone and the anemone receives nutrition from the presence of the clownfish. This is a mutually beneficial interaction. 38
Obtaining Needs As organisms try to survive in an ecosystem, their needs sometimes overlap with other organisms. Consider the beaver again. The beaver eats plant life. Many other rodents, however, also eat plant life. If there are more beavers and rodents than there are available plant life, what will happen? Write your thoughts below: 39
Competition Organisms in ecosystems often have needs that overlap with one another. Perhaps they eat the same food or they use the same type of shelter. When there are more organisms than there are resources, this leads to competition. Organisms must compete, or fight, for resources in order to survive. In this picture, three different types of animals are competing to eat the dead zebra. Can you find all three? 40
Competition in Plants Although we often think of animals when we talk about competition, plants also compete for resources Plants compete for water, access to light, the minerals in the soil and attention of certain animals for pollination and seed dispersion. 41
Interspecific Competition Competition can occur between different species or between members of the same species. Interspecific competition occurs between members of different species. (Hint: "inter" means between) Different plants on the forest floor must compete for sunlight in order to survive. 42
Intraspecific Competition Intraspecific competition occurs between members of the same species. (Hint:"intra" means among) For what resource(s) might these polar bears be fighting? 43
Case Study: Competition Competition occurs in a variety of ways over a variety of resources. Click below to watch a video about lion and hyena competition. Then, answer the questions. Click here to watch the competition video. 1. For what resource do hyenas and lions compete? 2. What is an example of interspecific competition in the video? 3. What is an example of intraspecific competition in the video? Answer 44
10 Competition occurs when organisms fight over resources in order to survive. True False Answer 45
11 Deer and squirrels both eat acorns. This behavior can lead to competition. A interspecific B intraspecific Answer 46
12 Male deer often lock antlers when they compete over territory. This is an example of competition. A interspecific B intraspecific Answer 47
Predator/Prey Interactions Predator/prey interactions occur as a result of organisms obtaining food to survive. The animal that is doing the hunting is called the predator, while the animal being hunted is the prey. Identify the predator and prey in each picture. 48
Predators and Prey Not all predators are big animals, and they're not always bigger than their prey. In any one ecosystem, there are many different predator prey interactions. Click here to watch a video about the Okavango delta in Botswana, Africa. 49
Mutually Beneficial Interactions In both competition and predator/prey interactions, one organisms benefits while the other organism suffers. In mutually beneficial interactions, all organisms benefit from the interaction. Answer The oxpeckers on the back of this hippo are looking for food to eat. They eat parasites, like ticks, from the backs of animals. How is this a mutually beneficial relationship? 50
Mutually Beneficial Interactions Click on the image below to watch a video about a relationship between ants and the acacia tree. Then, answer the questions. Answer 1. Describe two ways that the ants benefit the tree. 2. Describe how the tree benefits the ant. 51
Pollination 75% of all living flowering plants are pollinated by animals. Pollination is essential for these plants' survival and represent an important type of mutually beneficial relationship. Animals receive nutrition (nectar, pollen) while the plant is pollinated. 52
Obligate Mutualism Some mutually beneficial relationships are so special that they have become necessary for the organisms to survive. This is called obligate mutualism. The yucca tree, for example, is only pollinated by the yucca moth. The yucca moth also lays eggs inside of the flower and the larvae are able to eat some of the seeds as they develop. Without the yucca moth, the yucca tree would die because it would not be pollinated. Without the yucca tree, the yucca moth would have no method for the development of the larvae. 53
Case Study: Coral Reef Interactions Click here to watch a video about coral reef ecology. Then, answer the questions on the Coral Reef Interactions Worksheet. Answer 54
13 Which animal is the prey? A Cow B Grass Answer 55
14 Predator/prey interactions result from animals trying to meet their needs for shelter. True False Answer 56
15 In a mutually beneficial interaction, A both organisms are harmed. B one organism is harmed while the other benefits. C both organisms benefit. Answer D one organism benefits while the other experiences no impact. 57
16 Some flowers are shaped so that only the beak of a specific hummingbird can reach to the bottom to pollinate the flower. For this flower, the mutually beneficial interaction can be described as. A obligate B harmful Answer C abiotic D unnecessary 58
Population Dynamics Return to Table of Contents 59
Population Size Remember that a population is a group of the same species living together in one area. The size of a population is always changing based on biotic factors, abiotic factors and all interactions affecting that population. Answer Think back to corals. What is an example of a biotic factor, an abiotic factor and an interaction that would affect coral population size? Source: NOAA Photo Library 60
Population Size Suppose that we think about your family as a distinct population. How would the following events affect your population? Would they increase it or decrease it? Click in the box to check your answers. Your mom has a baby. A grandparent dies. Your older brother gets married and brings home his new wife. Increase Decrease Increase 61
Population Growth Populations in ecosystems work much the same way. Populations increase when: new organisms are born organisms immigrate, or join, the population 62
Populations decrease when: Population Growth organisms die organisms emigrate, or leave, a population Illegal poaching of elephants for their ivory tusks severely decreased many elephant populations. 63
Resources As populations try to obtain the resources necessary for survival, their population size changes accordingly. Consider a population of deer in a forest. For most of the year, they eat plants, fruit, seeds and nuts. During the winter, however, it is more difficult for them to find food. They will eat whatever they can find, including twigs, leaves and bark. If they are unable to find food, how will this affect their population size? Population will decrease. 64
Resources Think about how resources impact population size. Complete the blanks in the following statements. Click on the boxes to check your answers. When resources are readily available, population size will increase. When resources are not available, population size will decrease. 65
17 When plenty of resources are available, a population will decrease. True False Answer 66
18 What conditions will cause a population to decrease? Select all that apply. A New organisms are born. B Organisms die. C Emigration of organisms. Answer D Immigration of organisms. 67
Interspecific Competition In the grasslands of Africa, lions, leopards and hyenas all compete for the same food source. How do you think this affects their population sizes? 68
Interspecific Competition In interspecific competition, the strongest competitor will gain access to additional resources and experience a population increase. The weakest competitor will not have access to necessary resources and will experience a population decrease. If lions continually fight off hyenas, then lions will eat more food and have a stable or increasing population. Hyenas will eat less food and will have a decreasing population. 69
Intraspecific Competition Suppose that the oak tree in your front yard is discovered by a population of squirrels. The oak tree is tall and wide, offering abundant food and shelter. In light of these abundant resources, what do you predict will happen to the squirrel population? The squirrel population will increase. 70
Intraspecific Competition Over the next several years, the squirrel population increases dramatically due to the availability of shelter and food. During this time, the tree continues to be healthy and produces the same amount of food and offers the same amount of shelter. The amount of shelter and food necessary to allow the squirrel population to survive, however, has increased. What do you predict will happen to this squirrel population now? Since there is a large population but limited resources, the squirrel population will decrease due to intraspecific competition. Source: wildlifehotline.com 71
Population Growth For any population, in the presence of plentiful resources, the population will increase. However, as the population grows, the amount of resources necessary for survival also grows. 72
Population Growth If the population becomes bigger than the resources available, individuals will have to compete in order to survive (intraspecific competition). 73
Carrying Capacity Eventually, the population will level out at a certain size that is a balance between individuals and resources available. The population size that allows the largest population that can survive given the available resources is called the carrying capacity. 74
19 Interspecific competition can cause: A one population to decrease while another population increases. B both populations to increase. C both populations to decrease. Answer 75
20 When a population is introduced to unlimited resources, what will happen? A Population size will remain the same. B Population size will dramatically decrease. C Population size will dramatically increase. Answer 76
21 When does intraspecific competition affect population size? A When resources are plentiful. B When resources are limited. C When interspecific competition is also present. Answer D When a new environment is introduced. 77
22 When a population reaches its carrying capacity, what does this mean? A There are enough resources for the population to increase. B Interspecific competition forces the population to decrease. Answer C Predation controls the size of the population. D The population has reached a size that can be maintained by available resources. 78
Predator Prey Interactions Predator prey interactions also affect population size. The lynx is the predator of the snowshoe hare. The population of each is dependent on the other. 79
Predator Prey Interactions Think about predators and prey. How do you think the prey population is dependent on the predator? How do you think the predator population is dependent on the prey? 80
Case Study: Predator Prey Suppose you are studying a population of snowshoe hare (red) and lynx (green). When you begin the study, both populations are equal. List below the number of each in the population. Lynx: Hare: 81
Case Study: Predator Prey A disease enters the ecosystem and kills half of the lynx population. Cross off half of the lynx population below and then write the new population count. Lynx: Hare: What do you think will happen to the hare population? 82
Case Study: Predator Prey Because the predator's population has been cut in half, the hare population is not being eaten as much. The hare population increases. Write the new population count. Lynx: Hare: How do you think the populations will change next? 83
Case Study: Predator Prey Although the lynx population is small, it has an abundant food source due to the rise in hare population. Draw in 4 more lynx circles. Take away 4 hare circles due to increased predation. Write the new population count. Lynx: Hare: 84
Predator Prey Interactions Predators and prey are dependent on each other. If one population changes, it will create a change in the other population. Think about how predators and prey interact. Decide if each of the occurrences below would result in an increase or decrease. Prey population decreases. Predator population decreases. Predator population decreases. Prey population increases. Prey population increases. Predator population increases. Predator population increases. Prey population decreases. 85
23 Prey populations are dependent on predators but predator populations are not dependent on prey. True False Answer 86
24 Crown of thorn sea stars are predators of coral. If coral bleaching destroys the coral in an ecosystem, what will happen to the crown of thorns sea star population? A increase B decrease Answer 87
25 Ospreys are birds of prey that feed on fish. Suppose that one population of osprey is moved from their ecosystem because of human development. This population joins another population. The new population is now doubled in size. How will this affect the fish population? A increase B decrease Answer 88
Coral Reef Fish Survey Activity How do scientists gather information about the sizes of populations? Learn how to conduct a belt transect on coral reef fish in this simulation. 89
Energy in Food Webs Return to Table of Contents 90
Healthy Ecosystem A healthy ecosystem is composed of: Producers Consumers Decomposers What do you already know about these categories? Can you think of examples of organisms that fit into each category? 91
Producers Plants are called producers because they make their own food. They do this by using light energy from the sun, carbon dioxide from the air, and water from the soil to produce food. 92
Consumers Organisms that cannot make their own food are called consumers. They survive by consuming plants and animals. There are three groups of consumers : Herbivores, Omnivores, and Carnivores. 93
Herbivores Herbivores are animals that get their energy from eating only plants. 94
Omnivores Omnivores eat both plants and animals. 95
Carnivores A carnivore is an animal that eats only other animals. 96
Decomposers Bacteria and fungi are decomposers. They eat decaying matter (dead plants and animals). By doing this, they break them down and help them decompose. During decomposition, nutrients and minerals are released back into the soil. The nutrient rich soil helps plants grow. 97
Why are decomposers important? Decomposers are an essential part of the ecosystem. Consider a forest. When you walk in a forest, there are usually leaves and dead plants littering the ground. There are also dead animals that end up on the forest floor. What happens to these dead organisms? Why are there not piles and piles of dead organisms all over the forest? 98
Why are decomposers important? Decomposers eat dead plants and animals. By doing this, they eliminate a buildup of dead organisms. This process also recycles nutrients. The nutrients settle back into the soil, creating healthier soil. Healthy soil supports healthy plants that can create their own food and support the entire ecosystem. In this way, energy is constantly moving through an ecosystem, from one group to another. Producers Consumers Decomposers 99
26 Some animals can be called producers since they are food for other animals. True False Answer 100
27 Herbivores, omnivores, and carnivores are all. A Producers B Consumers C Decomposers Answer D None of the above 101
28 Decomposers are important because they make soil nutritious for other organisms. True False Answer 102
Ecosystem Interactions One way to illustrate the transfer of energy in an ecosystem is through food chains and food webs. Think about the difference between a chain and a web. How do you think this relates to food chains and food webs? 103
Food Chain A food chain shows one pathway of energy flow in an ecosystem. Each arrow shows where the energy is going. The energy in grass goes to the grasshopper when the grasshopper eats the grass. 104
Food Web In most communities, relationships are more complex than can be shown in a single food chain and energy flows in more than one direction. A food web is a diagram that shows the complex interactions and feeding relationships between all organisms in an ecosystem. 105
Atoms As energy moves throughout the food webs it does so as atoms. Atoms are the small building blocks that make up all matter. They are the smallest particle of an element. 106
Cycle of Atoms Atoms of both the living and nonliving things in an ecosystem are repeatedly transferred. As the atoms move along, they transfer energy and nutrients. 107
Matter Cycles Through the Food Web If it was possible to label a single Carbon atom, for example,we could track it cycling through the entire food chain. 108
Teacher Notes Aquatic Food Web The same can be said about an atom cycling through an aquatic food web. 109
Ecosystem Interactions By looking at food chains and food webs, we can hypothesize (guess) what will happen to organisms if certain changes occur. If a disease destroys the grasshopper population, the snake population will have nothing to eat and that population will decrease as well. Answer If the grasshopper population is destroyed, what would happen to the grass population? 110
29 Food chains follow a single path of energy flow. True False Answer 111
30 Food are connected by many different paths. A webs B chains Answer 112
31 If a disease destroys the dragonfly population, what animal population will not decrease? A Salamander B Trout C Frog Answer D Phytoplankton Source: EPA 113
32 Scientists discover that the trout population has become toxic due to pollution in the water. What other population should they monitor for toxicity? A Mayfly B Bald eagle Answer C Dragonfly D Salamander Source: EPA 114
Desert Food Web Activity Food webs show the flow of energy through an ecosystem. Use the given information to create a food web for a desert ecosystem. 115