Ecology Life Interacts with the Earth

1. Ecology Life Interacts with the Earth

2. The Biosphere as a System • Biosphere is the part of our planet that contains all of its living organisms • Ecosystems are composed of organisms and geologic or abiotic components that function in a balanced, interactive fashion.

3. An ecosystem

4. 1. The biosphere as a system ● Organisms of the ecosystem ● Producers (autotrophs) ● Consumers (heterotrophs)

5. Plants: examples of autotrophs

6. Koala: example of a heterotroph

8. 1. The biosphere as a system • ● Inputs to the ecosystem: • what life is made of • Carbon • Nutrients • Water • Energy

9. 1. The biosphere as a system • ● Processes and outputs: • how organisms live and • grow • Metabolism • Photosynthesis • Respiration

12. Energy Flow Through Ecosystems • Communities have some common processes including energy flow and matter cycling through the system. • Food webs, food chains, and food pyramids are three ways of representing energy flow. The flow of energy through an ecosystem. Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com) Original inorganic elements are mostly returned to soil and producers; can be used again by producers and no new input is required.

13. Energy Flow in Ecosystems • Energy flow in ecosystems, as with all other energy, must follow the two laws: • Energy is neither created nor destroyed, but instead changes from one form to another (potential to kinetic). • When energy is transformed from one form to another, some usable energy is lost as heat. • The ultimate source of energy for nearly all life is the Sun. One exception: communities of organisms around ocean vents where food chain begins with chemosynthetic bacteria that oxidize hydrogen sulfide generated by inorganic chemical reactions inside the Earth's crust. In this special case, the source of energy is the internal heat engine of the Earth.

14. Energy Flow in Ecosystems • Food chains indicate who eats whom in an ecosystem. • They represent one path of energy flow through an ecosystem. • Natural ecosystems have numerous interconnected food chains. • Each level of producer and consumers is a trophic level. • Some primary consumers feed on plants and make grazing food chains; others feed on detritus.

15. Energy Flow in Ecosystems • The trophic structure of an ecosystem forms an ecological pyramid. • The base of this pyramid represents the producer trophic level. At the apex is the highest level consumer, the top predator. • A pyramid of numbers is based on how many organisms occupy each trophic level. The pyramid of biomass is calculated by multiplying the average weight for organisms times the number of organisms at each trophic level. • An energy pyramid illustrates the amounts of energy available at each successive trophic level. The energy pyramid always shows a decrease moving up trophic levels Energy flow and the relative porportions of various levels in grazer and decomposer food chains. Images from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com)

16. Life is Organized in a Hierarchy • Universe • Galaxies • Solar Systems • Planets • Biosphere • Ecosystems • Communities • Populations • Organisms • Organs • Tissues • Cells • Molecules • Atoms • Subatomic particles

17. Classification of Communities • These two basic types of community contain eight smaller units known as biomes. • A biome is a large-scale category containing many communities of a similar nature, whose distribution is largely controlled by climate There are two basic categories of communities: terrestrial (land) and aquatic (water).

18. Biomes • Terrestrial Biomes: • tundra, • grassland, • desert, • taiga, • temperate forest, • tropical forest. • Aquatic Biomes: • Marine • freshwater. Costa Rican cloud forest. Image from the Botanical Society of America, http://images.botany.org/bsa/set-01/01-197v.jpg.

19. Biomes • Terrestrial Biomes: • tundra, • grassland, • desert, • taiga, • temperate forest • tropical forest • Aquatic Biomes: • Marine • freshwater Fall color in the eastern deciduous forest. Note the presence of a few evergreens among the hardwoods.Image from the Botanical Society of America, http://images.botany.org/bsa/set-01/01-036v.jpg.

20. Biomes • Terrestrial Biomes: • tundra • grassland • Desert/shrubland • taiga • temperate forest, • tropical forest • Aquatic Biomes: • Marine • freshwater Chaparral vegetation (predominantly Adenostema) in California. Image from the Botanical Society of America website, http://images.botany.org/bsa/set-01/01-110v.jpg.

21. Biomes • Terrestrial Biomes: • tundra • grassland • desert • taiga • temperate forest • tropical forest • Aquatic Biomes: • Marine • freshwater Short grass prairie, Nebraska. Image from the Botanical Society of America website, http://images.botany.org/bsa/set-01/01-068v.jpg.

22. Biomes • Terrestrial Biomes: • tundra • grassland • desert • taiga • temperate forest • tropical forest • Aquatic Biomes: • Marine • freshwater Saguaro and cholla cacti in association with palo verde trees in the Sonoran desert, AZ. Note the lack of a canopy and the scarcity of ground cover. Image from the Botanical Society of America website, http://images.botany.org/bsa/set-01/01-097v.jpg.

23. Biomes • Terrestrial Biomes: • tundra • grassland • desert • Taiga/Boreal forest • temperate forest • tropical forest • Aquatic Biomes: • Marine • freshwater Image of a Larix-dominated area of the taiga biome. Image from the Botanical Society of America website, http://images.botany.org/bsa/set-01/01-027v.jpg.

24. Biomes • Terrestrial Biomes: • tundra • grassland • desert • taiga • temperate forest • tropical forest • Aquatic Biomes: • Marine • freshwater Temperate rain forest, Washington. Note the dense understory of ferns and herbaceous plants. Image from the Botanical Society of America website, http://images.botany.org/bsa/set-01/01-134v.jpg.

25. Biomes • Terrestrial Biomes: • tundra • grassland • desert • taiga • temperate forest • tropical forest • Aquatic Biomes: • Marine • freshwater View of the tundra, locality unknown. Image from http://ths.sps.lane.edu/biomes/tundra3/tundra3.html.

26. Climate, Altitude and Terrestrial Biomes • Climate controls biome distribution by an altitudinal gradient and a latitudinal gradient. • With increases of either altitude or latitude, cooler and drier conditions occur. • Cooler conditions can cause aridity since cooler air can hold less water vapor than can warmer air. Effect of temperature on precipitation. Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com)

27. Climate, Altitude and Terrestrial Biomes Rainshadows and deserts. Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com)

28. Aquatic Biomes • Conditions in water are generally less harsh than those on land. • Despite covering 71% of the Earth's surface, areas of the open ocean are a vast aquatic desert containing few nutrients and very little life. • Dissolved nutrients controls many local aquatic distributions. • Aquatic communities are classified into: freshwater (inland) communities and marine (saltwater or oceanic) communities. Species diversity and salt concentration. Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com)

29. Marine Biomes • There are two basic categories to this biome: benthic and pelagic. • Benthic communities (bottom dwellers) are subdivided by depth: the shore/shelf and deep sea. • Pelagic communities (swimmers or floaters suspended in the water column) include planktonic (floating) and nektonic (swimming) organisms. • The upper 200 meters of the water column is the euphotic zone to which light can penetrate. Zones within the marine biome. Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com)

30. Fresh Water Biomes • The freshwater biome is subdivided into two zones: running waters and standing waters. • Lakes are larger than ponds, and are stratified in summer and winter. The epilimnion is the upper surface layer. The hypolimnion is the cold lower layer. • Mixing between upper and lower layers in a pond or lake occurs during seasonal changes known as spring and fall overturn. Lake Overturn. Image from Purves et al., Life: The Science of Biology, 4th Edition, by Sinauer Associates (www.sinauer.com) and WH Freeman (www.whfreeman.com)