Ecosystems

1. Ecosystems A study of balance and cycles

2. Key Terms • Ecosystem • Consists of a biotic community and the abiotic factors that affect it • Ex – a rain forest, including the animals, plants, soil, rain, sunlight, and temperature • Biotic factors • Living or once-living organisms in the environment • Ex – gorilla, red-eyed tree frog, moss, bacteria • Abiotic factors • All the non-living, physical features of the environment • Ex. sunlight, soil, water, and temperature

3. Levels of organization • Organism • A single individual in a population • Ex – the oak tree growing in my yard • Population • All of the individuals of one species that live in the same area at the same time • Ex. – All oak trees in my neighborhood • Community • Populations of different species that interact in some way • Ex. – Oak trees, squirrels, rabbits, mice, grass, robins, humans

4. Levels of Organization, cont. • Ecosystem • Communities and abiotic factors that affect them • Ex. Community + soil, light, temperature, etc. • Biosphere • All the ecosystems on Earth

5. Populations • Population density • The number of organisms in a given area • Formula - # of organisms / area • The more organisms in a given space, the denser the population • Limiting factor • Any biotic or abiotic factor that restricts (limits) the number of individuals in a population • Ex. Food supply, # of predators, disease, available shelter

6. Limiting Factors • 1. Choose an organism. • 2. Write five limiting factors for that organism. Be as specific as possible. • Ex. Cow • 1. Disease - Mad cow disease • 2. Humans – Humans slaughter cows for food • 3. Living space – Farms have limited space to house the cows.

7. Relationships • Symbiosis • Any close relationship between two or more species • Parasitism, mutualism, and commensalism are all types of symbiosis • Parasitism • Relationship that benefits one (the parasite) and does definite harm to the other (host) • Ex – Tapeworms benefit by getting nutrients from a dog, but the dog is harmed by the tapeworms

8. Relationships, cont. • Mutualism • A relationship in which both organisms benefit • Ex Yucca moth and desert yucca plant – moth gets a food source and place for eggs; plant gets its flowers pollinated • Commensalism • A relationship in which one organism benefits, but the other is neither harmed nor helped. • Ex. Sea anemone and anemone fish – The fish are protected by the sea anemone, but the sea anemone are not affected by the fish

9. Cycles • Many abiotic factors change form as they travel through a cycle • Matter is not destroyed, but it changes form • Examples • Water • Carbon • Nitrogen

10. Water Cycle • Evaporation – Liquid water found in lakes, oceans, ponds, rivers, etc. evaporates when heat is added. The water takes the gaseous form of water vapor • Condensation – Gaseous water vapor condenses when it is cooled and has a solid on which it can condense. The water becomes liquid form. • Freezing – Some clouds are high enough in the atmosphere that the water freezes, forming snow or hail • Precipitation –Liquid or solid water collects in clouds, and as more water collects, it becomes heavy enough to fall as rain, snow, or hail

11. Water Cycle, cont. • Run-off – Precipitation hits the ground, is not absorbed, but flows from high elevation to low elevation. • Ground water – Precipitation hits the ground and is absorbed into the ground • Hydration of living organisms – Organisms take in water by drinking, eating, taking water in through roots, and osmosis • Excretion – Animals release water in their liquid wastes • Transpiration – Plants release water from stomata

12. Carbon Cycle • Photosynthesis – Plants remove carbon dioxide from atmosphere to make carbohydrates • Respiration – Other organisms eat the plants. In respiration, they use the energy from the carbohydrates. Carbon dioxide is released as a waste product • Decay – Organisms die. The carbon in their decaying remains is returned to the ground • Combustion – Carbon is released into the atmosphere when fossil fuels (ex coal and oil) are burned

13. Nitrogen Cycle • Nitrogen is a gas in our atmosphere. It is also found in organisms in proteins and nucleic acids. • Nitrogen gas – In the atmosphere, nitrogen will combine with oxygen in the presence of high temperatures and pressures (lightning) to form nitrogen dioxide • Nitrogen dioxide combines with rain to form an acid, which falls to the ground with the rain. • In the ground, bacteria “fix” nitrogen so that it can be used by plants

14. Nitrogen Cycle, cont. • Plants use nitrogen as a fertilizer. The nitrogen is used to build proteins, which are necessary for growth • Animals eat plants, taking in the proteins containing nitrogen. • Animals release wastes, which contain nitrogen. These wastes may be used as fertilizer. • Some bacteria convert nitrogen in the soil back into nitrogen gas, which is released into the atmosphere

15. Energy in Ecosystems • Energy travels through an ecosystem, changing form • Common forms of energy include light, chemical, mechanical, and heat energy • Organisms gain energy by: • Using light or chemical energy to produce their own food (producers) • Eating other organisms (consumers)

16. Producers vs. Consumers • Producers • Plants and some bacteria • Photosynthesis – use light energy to create carbohydrates • Chemosynthesis – use chemical energy to create carbohydrates • Found in organisms deep in ocean ridges • Consumers • Eat other organisms for energy • Ordered by primary (eat consumers), secondary (eat primary consumers), and tertiary (eat secondary consumers)

17. Food Chains and Food Webs • Food chains show relationships among a select group of producers and consumers. • The chain shows the flow of energy as one organism eats another. • Chains are RARELY more than five organisms long • Consumers get only a fraction of the energy contained in the organism they eat. • Some energy is used by the original organism • Much energy is lost as heat energy

18. Example of a Food Chain

19. Food Chains and Food Webs, Cont. • Food webs • Show the complexity of consumer/producer relationships in an ecosystem • Used to show that more than one organism may eat a producer or prey AND that an organism may have more than one food source • Typically, producers are near the bottom of the web and secondary/tertiary consumers are near the top • Arrows indicate the direction of energy flow

20. Example of a Food Web

21. Energy Pyramid • Diagram used to show producer and consumer relationships • Emphasizes the relationship of number of prey per organism and the amount of energy that gets transferred from one level (ex. producer) to another level (ex. primary consumer) • Only about 10% of the energy from one level is passed on to the next level • Not all parts of an organism are eaten • Not all organisms at one level are eaten • Some energy is “lost” as heat energy • Therefore, in an ecosystem, we have MANY producers and primary consumers. As we move up the energy pyramid, the ecosystem can sustain fewer and fewer organisms because there is less and less energy available