Chapter 13: Principles of Ecology

1. Chapter 13: Principles of Ecology • 13.1: Ecologists Study Relationships • Objectives: Summarize the levels of organization that ecologists study. • Describe research methods ecologists use the study the environment. • Words to Know: Ecology, Community, Ecosystem, Biome, organism, population

2. What is Ecology? • Ecology is the study of the interactions among living things, and between living things and their surroundings.

3. Levels of Organization • 1. Organism – an individual species. • Ex: an alligator. • 2. Population – a group of the same species that lives in one area. • Ex: alligators in the swamp. • 3. Community – a group of different species that live together in an area. • Ex: alligators, turtles, birds, fish and plants in the Florida Everglades. • 4. Ecosystem – includes all of the organisms as well as the climate, soil, water and rocks. • Ex: Florida everglades with all of the plants, animals, soil, water and sun. • 5. Biome – a major regional or global community of organisms. • Ex: Tropical rainforest, Tundra, Desert • What level of organization describes a flock of pigeons in the park?

4. Levels of Organization

5. Ecological Research Methods • Observation • Observation is the act of carefully watching something over time. • This can occur over short or long periods of time. • One type of population observation is surveys. • Direct Surveys are used for species that are easy to follow. (naked eye, binoculars) • Indirect Surveys are used for species that are difficult to track. (signs of presence). • Radio Telemetry is used to track animal movement. • Population sampling can also be used. • To monitor plant populations, scientists use Quadrat Sampling. • Scientists focus on the quadrat of plants in a random area and estimate from there. • How might a scientist use observation to study a population of mountain goats? Explain your answer.

6. Ecological Research Methods • Experimentation • Experiments can be performed in the field or in the lab. • A lab experiment allows for more control, but a field experiment gives a more accurate picture of how the organisms interact in a natural setting. • What is the difference between a lab experiment and a field experiment?

7. Ecological Research Methods • Modeling • Modeling is used when a question cannot be answered by observation or experimentation. • Models are created with the use of real data, but are lab tools. • Models can be used to: track populations, find vegetation, predict snow. • How does modeling differ from experimentation?

8. 13.2: Biotic and Abiotic Factors • Objectives: Identify biotic and abiotic factors in an ecosystem. • Describe how a change in one factor in an ecosystem can affect others. • Warm Up: Picture yourself in the woodlands and then the desert. If I picked up a handful of soil in each place, what differences would you find? • Words to Know: Biotic, Abiotic, Biodiversity, Keystone Species.

9. An Ecosystem Includes both Biotic and Abiotic Factors. • Biotic Factors are living things, such as plants, animals, fungi and bacteria. • Abiotic Factors are nonliving things, such as moisture, temperature, wind, sunlight, water and soil. • What is the difference between biotic and abiotic factors?

10. Biodiversity • ALL species are affected by changes in biotic and abiotic factors in an ecosystem. • Biodiversity is the assortment, or variety, of living things in an ecosystem. • The amount of biodiversity found in an area depends on many factors, including moisture and temperature.

11. Keystone Species • The change in a single biotic or abiotic factor can cause changes that are barely noticeable or cause the extinction of a species. • A Keystone Species is a species that has an unusually large effect on its ecosystem. • Ex: the beaver. By felling trees, they create ponds, wetlands, and streams. This can lead to huge changes in an ecosystem. • See figure 13.6 • Explain why the Pacific Salmon, introduce in section 13.1, could be considered a keystone species.

12. Keystone Species cont…

13. 13.3: Energy in Ecosystems • Objectives: Describe the roles of producers and consumers in ecosystems. • Compare photosynthesis to chemosynthesis. • Warm Up: 6H2O + 6CO2  C6H12O6 + 6O2 • Why does life as we know it depend upon the formula written above? • Words to Know: Producer, Autotroph, Consumer, Heterotroph, Chemosynthesis, photosynthesis.

14. Producers • Producers are organisms that get their energy from nonliving resources. • Producers are also called Autotrophs meaning “self-nourishment”. • Consumers are organisms that get their energy by eating other living or once living resources, such as plants or animals. • Consumers are also called Heterotrophs meaning “different-nourishment”. • All ecosystems depend on producers because they provide the basis for the ecosystem’s energy. • Most producers use sunlight to make food, therefore almost all living things depend directly or indirectly on the sun as a main energy source. • How would a long-term drought affect producers and consumers?

15. Almost All Producers Obtain Energy from Sunlight. • Photosynthesis is a two-stage process used by most producers to make food. • Chemosynthesis is a process in which an organism form carbohydrates using chemical rather than light, as an energy source. • How do photosynthesis and chemosynthesis differ?

16. 13.4: Food Chains and Food Webs • Objectives: Describe the structure of a food chain. • Explain how food chains and trophic levels are related. • Analyze feeding relationships in a food web. • Warm Up: What do you get from food? How does energy and matter come from the food you eat? What other way could you get energy for your body? • Terms to Know: Food Chain, Herbivore, Carnivore, Omnivore, Detritivore, Decomposer, Specialist, Generalist, Trophic Level, Food Web.

17. Food Chain • A Food Chain is a sequence that links species by their feeding relationships. • Rather than describe every potential relationship, this model chain only follows the connection between one producer and a single chain of consumers within an ecosystem. • Ex: Sun  Grass  Cottontail  Hawk

18. Types of Consumers • Herbivores are organisms that eat ONLY plants. • Ex: Deer, rabbits • Carnivores are organisms that eat ONLY animals. • Ex: Hawks, sharks • Omnivores are organisms that eat BOTH plants and animals. • Ex: Humans, bears • Detritivores are organisms that eat detritus, or dead organic matter. • Ex: Vultures, Hyena • Decomposers are detritivores that break down organic matter into simpler compounds. • Ex: Bacteria, fungus • A Specialist is a consumer that primarily eats one specific organisms or feeds on a very small number of organisms. • Ex: Florida Snail Kite, depends primarily on apple snails. • Generalists are consumers that have a varying diet. • Ex: Grey wolf.

19. Trophic Levels • Trophic Levels are the levels of nourishment in a food chain. • Ex: Producer  Herbivore  Carnivore has THREE Trophic Levels. • The carnivore is the highest trophic level. • Energy flows up the food chain from the lowest trophic level to the highest. • Primary Consumers are herbivores. • Secondary Consumers are Carnivores that eat Herbivores. • Tertiary Consumers are carnivores that eat secondary consumers. • Organisms can fall at different trophic levels based on where they fall in a food chain. • What is the connection between food chains and trophic levels?

20. Food Web • A Food Web is a model that shows the complex network of feeding relationships and the flow of energy within and sometimes beyond an ecosystem. • At each link in a food web, some energy is stored within an organism, and some energy is dissipated into the environment. • How might the introduction of a new predator affect the flow of energy through a food web?

21. Food Web

22. 13.5: Cycling of Matter • Objectives: Summarize Earth’s hydrologic and biogeochemical cycles. • Relate cycling of matter to ecosystems. • Warm Up: As humans, we are made of cells. Where does all that material come from? What would you include on a shopping list of elements that are critical to a human? • Words to Know: Hydrologic cycle, Biogeochemical cycle, Nitrogen Fixation

23. Water Cycle • Matter changes form, but it does not disappear, it is used over and over again in cycles. • The Hydrologic Cycle (water cycle) is the circular pathway of water on earth from the atmosphere, to the surface, below, ground and back. • Water Storage (River )Evaporation (liquid to gas) Condensation (gas to liquid) Precipitation (rain, snow, sleet, hail) Runoff (gravity pulls down) Water Storage

24. Water Cycle

25. Elements Essential for Life also Cycle Through Ecosystems. • A Biogeochemical cycle is the movement of a particular chemical through the biological and geological parts of an ecosystem. • Just as water changes states, so may other chemicals as they pass though cycles.

26. The Oxygen Cycle • Plants, animals, and most other organisms need oxygen for cellular respiration. • Plants release oxygen as a waste product of photosynthesis. • In turn, humans and other organisms take in this oxygen and release it as carbon dioxide through cellular respiration. • Explain how deforestation might affect the oxygen cycle?

27. The Oxygen Cycle

28. The Carbon Cycle • Carbon is the building block of life – it is key to the structure of all organisms on our planet. • Carbon exists in several forms: CO2 gas, bicarbonate dissolved in water, fossil fuels, limestone and organic matter in soil. • The simplest transfer of carbon occurs between plants and animals. • Plants use energy from the sun to convert carbon dioxide from the air into organic material that becomes a part of the plant’s structure. • Carbon then moves through the biotic world as one organism eats another. • Carbon is returned to the atmosphere as carbon dioxide by respiration or decomposition.

29. The Carbon Cycle

30. The Nitrogen Cycle • 78% of the Earth’s atmosphere is made of nitrogen gas. • Certain types of bacteria convert gaseous nitrogen into ammonia (NH3) in a process called Nitrogen Fixation. • Some nitrogen fixing bacteria live on nodules (bumps) on the roots of bean and pea plants. • Nitrates release by soil are taken up by plants, that convert them into amino acids and proteins. • Animals then eat the plants and get the nitrogen. • When decomposers break down animal excretions or dead animal and plant matter, nitrogen is returned to the soil through ammonification. • Denitrifying bacteria use nitrate as an oxygen source and release nitrogen gas into the atmosphere.

31. The Nitrogen Cycle

32. The Phosphorus Cycle • Most of the phosphorus cycle takes place at and below ground level. • Phosphate is released by the weathering of rocks. • Plants and some fungus are able to take up phosphate. • Phosphorus moves to consumers through the food chains and webs. • When living things die and are decomposed, phosphorus is released back into the Earth. • Choose one of the biogeochemical cycles, and list the key processes involved in the cycling of elements.

33. The Phosphorus Cycle

34. 13.6 Pyramid Models • Objectives: Trace the flow of energy through an ecosystem, using an energy pyramid. • Relate energy pyramids to food chains and trophic levels. • Compare and contrast a biomass pyramid and a pyramid of numbers. • Warm Up: How is food energy measure? What do Calories measure? • Words to Know: Biomass, Energy Pyramid

35. Energy Pyramid • Ecosystems get their energy from sunlight. That energy then flows through food chains. • Some energy gets lost in the process in the form of heat, so each level in a food chain contains much less energy than the group before it.

36. Loss of Available Energy • Biomass is a measure of the total dry mass of organisms in a given area. • When an organism consumes biomass a great deal of energy is given off as heat and waste. • Scientists use the “Rule of 10”. • Each level in a food chain only gets 10% of the available energy from what it eats.

37. Energy Pyramids • An Energy Pyramid is a diagram that compares energy used by producers, primary consumers, and other trophic levels. • Producers ALWAYS make up the bottom layer of the pyramid (they have the most energy). • Sections become progressively smaller as you go up the pyramid since the amount of usable energy sharply decreases. • RULE: As you move up the energy pyramid, the amount of available energy goes down. • Draw an energy pyramid for the desert food chain introduced in section 13.4. Use arrows to illustrate the flow of energy.

38. Other Pyramid Models • A Biomass Pyramid is a diagram that compares the biomass of different trophic levels within an ecosystem. • The pyramid shows the mass of producers needed to support primary consumers, the mass of primary consumers required to support secondary consumers and so on. • A Pyramid of Numbers shows the numbers of individual organisms at each trophic level in an ecosystem. • If a scientist wanted to compare the exact number of organisms at each trophic level within a desert ecosystem, which pyramid model would he or she use? Explain.

39. Other Pyramid Models Pyramid of Numbers Biomass Pyramid