1. The Earth’s Ecosystems Chapter 17

2. Land Ecosystems  Abiotic = nonliving factors that influence the types of plants & animals that live in the area. The Earth’s Biomes  Biome = a geographic area characterized by certain types of plant & animals communities. A biome contains a number of smaller but related ecosystems within it. Section 1

3. Forests  They develop where there is enough rain & where the temperature is not too hot in the summer or too cold in the winter. 3 types of forest biomes: Temperate Deciduous Forests  Deciduous = trees that lose their leaves in the fall to conserve water during the water.  In a temperate deciduous forest, mammals, birds, & reptiles thrive on the abundance of leaves, seeds, nuts, & insects. Section 1

4. Forests: Cont.  In forests, plant growth occurs in layers. The leafy tops of the trees reach high above the forest floor, where they receive full sunlight. Beneath the tree layer, woody shrubs & bushes catch the light that filters through the tree. Grasses, herbs, ferns, & mosses are scattered across the forest floor. Most of the flowering plants bloom, & produce seeds in early spring, before the trees leaf out. Section 1

5. Forests: Cont. Coniferous Forests  Don’t change very much from summer to winter. Found in areas with long, cold winters. These forests consists mainly of evergreen trees  Conifers = trees that produce seeds in cones. Identified by their compact, needlelike leaves. These needles have a thick waxy coating that prevents them from drying out & being damaged during the winter.  Not many large plants grow beneath conifers, partly because very little light reaches the ground. Section 1

6. Forests: Cont. Tropical Rain Forests  The tropical rain forest has more biological diversity than any other biome on the planet  Diversity = more species than any other biome  Canopy or treetop are the preferred living site for animals here.  Nutrients are in the vegetation – not the soil. Farmers who cut down the forest have to move after 2 years. Section 1

7. Grasslands  Regions where grasses are the major type of vegetation. Temperate Grasslands  Mainly grasses mixed with a variety of flowering plants. There are few trees because fires prevent the growth of most slowing growing plants. The world’s temperate grasslands support small, seed- eating mammals, such as prairie dogs & mice, & large herbivores, such as the bison of North America Section 1

8. Grasslands: Cont. Savanna  Savanna = a tropical grassland with scattered clumps of trees. During the dry season, the grasses die back, but the deep roots survive even through months of drought. During the wet season, the savanna may receive as much as 150 cm of rain. The savannas of Africa are inhabited by the most abundant & diverse groups of large herbivores in the world. These include elephants, giraffes, zebras, gazelles, & wildebeests. Section 1

9. Deserts  Deserts = hot, dry regions that support a variety of plants & animals. Most water that falls to the ground evaporates. Organisms have evolved ways to survive the extreme temperatures & little water.  Cactus store water in their stems & roots  Some flowering plants bloom, bear seeds, & die within weeks after a heavy rain.  Kangaroo rats never need to drink. They recycle water from the foods they eat.  Jack rabbits’ huge ears help them get rid of body heat. Section 1

10. Tundra  Tundra = in the far north (Arctic tundra) & on the tops of high mountains (Alpine tundra), the climate is so cold that no trees can grow Arctic Tundra  During the short growing season, only the surface soil thaws  Permafrost = the soil below the surface stays frozen all the time.  The layer of unfrozen soil above the permafrost is too shallow for deep-rooted plants to survive. Section 1

11. Tundra: Cont.  Grasses, sedges, rushes, & small woody shrubs are common. A layer of mosses & lynches grows beneath these plants on the surface of the ground.  Tundra animals include large mammals such as caribous, musk oxen, & wolves, as well as smaller animals, such as lemmings, shrews, & hares. Migratory birds are abundant in summer. Alpine Tundra  Receive a lot of sunlight & precipitation, mostly in the form of snow Section 1

12. Land Ecosystems: REVIEW 1. How is the climate of temperature grasslands different from that of savannas? 2. Describe three ways that plants & animals are adapted to the desert climate. 3. Where are most of the nutrients in a tropical rain forest? 4. Could arctic tundra accurately be called a frozen desert? Why or why not? Section 1

13. Marine Ecosystems  Cover almost three-quarters of the Earth’s surface. Contain almost 97% of the Earth’s water supply.  The largest animals on Earth inhabit them, along with billions of microscope creatures.  Marine = ecosystem is one that is based on salty water.  Their habitats range from dark, cold, high- pressure depths to warm sandy beaches; from icy polar waters to rocky coastlines. Section 2

14. Abiotic Factors Rule  Shaped by abiotic factors = temperature, the amount of sunlight penetrating the water, the distance from land, & the depth of the water. Sunny Waters  Phytoplankton = the most abundant producers in the ocean; they are microscopic photosynthetic organisms that float near the surface of the water.  Zooplankton = consumers that feed on the phytoplankton; small animals that along with phytoplankton, form the base of the oceans’ feeding relationships. Section 2

15. Wonderful Watery Biomes The Intertidal Zone  This area is above water part of the day, when the tide is out, & is often battered by waves. Mud flats, rocky shores, & sandy beaches are all in the intertidal area. The Neritic Zone  Water in this area is generally less than 200 m deep & usually receives a lot of sunlight. Diverse & colorful coral reefs exist in the water over the continental shelf, where the water is warm, clear, & sunny. Section 2

16. Wonderful Watery Biomes: Cont. The Oceanic Zone  Past the continental shelf, the sea floor drops sharply. This is the deep water of the open ocean. To a depth of about 200 m, phytoplankton are the producers. At greater depths, no light penetrates, so most organisms obtain energy by consuming organic material that falls from the surface. Section 2

17. Wonderful Watery Biomes: Cont. The Benthic Zone  The benthic zone is the sea floor. It extends from the upper edge of the intertidal zone to the bottom of the deepest ocean waters. Organisms that live on the deep-sea floor obtain food mostly by consuming material that filters from above. Some bacteria are chemosynthetic, which means they use chemicals in the water near thermal vents to make food. A thermal vent is a place on the ocean floor where heat escapes through a crack in the Earth’s crust. Section 2

18. A Closer Look  Marine environments provide most of the water for Earth’s rainfall through evaporation & precipitation.  Humans harvest enormous amounts of food from the oceans & dump enormous amounts of waste in to them. Section 2

19. A Closer Look: Cont. Coral Reefs  One of the most biologically diverse biomes.  Corals live in a close relationship with single- celled algae. The algae produce organic nutrients through photosynthesis. This provides food for the coral. The coral provide a place in the sun for the algae to live. The foundation of the reef is formed from coral skeletons that have built up over thousands of years. Section 2

20. A Closer Look: Cont. The Sargasso Sea  In the middle of the Atlantic Ocean is a large ecosystem with no land boundaries.  Sargassum = a type of algae usually found attached to rocks on the shore of North America, but it forms huge floating rafts in the Sargasso Sea.  Animals adapted to this environment live among the algae. Most of the animals are the same color as the Sargassum. Section 2

21. A Closer Look: Cont. Polar Ice  Make up a very unusual marine biome because of the ice.  The waters are rich in nutrients from the surrounding landmasses. These nutrients support large populations of plankton.  The plankton in turn support a great diversity of fish, seabirds, penguins, & sea mammals, such as sea lions. Section 2

22. A Closer Look: Cont. Estuaries  Estuary = an area where fresh water from streams & rivers spills into the ocean.  The amount of salt in an estuary changes frequently. The fresh water that spills into an estuary is rich in nutrients that are carried by water running off the land. Because estuaries are so nutrient-rich, they support large numbers of organisms. They are crowded with masses of plankton, which provide food for many larger animals. Section 2

23. A Closer Look: Cont. Intertidal Areas  Some amazing adaptations can be found among the organisms that inhabit the intertidal areas. Mud flats are home to many burrowing worms & crabs & the shorebirds that feed on them. Sandy beaches are also home to burrowing worms, clams, crabs, & plankton that live among the sand grains.  On rock shores, organisms either have tough holdfasts or are able to cement themselves to a rock to avoid being swept away by crashing waves. Section 2

24. Marine Ecosystems: REVIEW 1. Explain how a coral reef is both living & dead. 2. Why do estuaries support such an abundance of life? 3. Explain how the amount of light an area receives determines the kinds of organisms that live in the open ocean. Section 2

25. Freshwater Ecosystems  Characterized by abiotic factors primarily the speed the water is moving. Water on the Move  Brooks, streams, & rivers are ecosystems based on moving water.  Tributary = a river or stream flowing into a larger river or lake.  Organisms that live in moving water require special adaptations to avoid being swept away with the current. Section 3

26. Still Waters  Ponds & lakes have different ecosystems than streams & rivers. There are 3 zones lakes are divided into. Where Water Meets Land  Littoral Zone = the zone closest to the land.  This zone has many inhabitants.  Plants: cattails, rushes, water lilies, & submerged pond weeds  Animals: snails, small arthropods, insect, clams, worms, frogs, salamanders, water turtles, water snakes & various kinds of fishes. Section 3

27. Still Waters: Cont. Life at the Top  Open-water Zone = extends from the littoral zone across the top of the water and only goes as deep as light can reach.  Plants: phytoplankton most abundant photosynthetic organism.  Animals: bass, blue gills, lake trout, & other fish Section 3

28. Still Waters: Cont. Life at the Bottom  Deep-water Zone = zone below the open-water zone, where no light reaches.  Animals: catfish, carp, worms, insect larvae, crustaceans, fungi, & bacteria live here. These organisms feed off dead organic material that falls down from above. Section 3

29. Wetlands  Wetland = an area of land where the water level is near or above the surface of the ground for most of the year.  Support a variety of plant & animal life  These play an important role in flood control. During heavy rains or spring snow melt, wetlands soak up large amounts of water. The water in wetlands also seeps in to the ground, replenishing underground water supplies. Section 3

30. Wetlands: Cont. Marshes  Marsh = a treeless wetland ecosystem where plants such as cattails & rushes grow.  Found in shallow waters along the shores of lakes, ponds, rivers, & streams.  The plants in a marsh vary depending on the depth of the water & on the location of the marsh.  Plants: Grasses, reeds, bulrushes, & wild rice  Animals: Muskrats, turtles, frogs, & redwing blackbirds Section 3

31. Wetlands: Cont. Swamps  Swamp = a wetland ecosystem where trees & vines grow.  Occur in low-lying areas & beside slow-moving rivers. Most swamps are flooded only part of the year depending on rainfall.  Plants: willows, bald cypresses, water tupelos, oaks, & elms, poison ivy, Spanish moss, water lilies  Animals: variety of fish, snakes, & birds. Section 3

32. From Lake to Forest  How can a lake or pond disappear?  Water entering a standing body of water usually carries nutrients & sediment along with it.  These materials then settle to the bottom. Dead leaves for overhanging trees & decaying plant & animal life also settle to the bottom. Gradually, the pond or lake fills in. Plants grow in the newly filled areas, closer & closer toward the center. With time, the standing body of water becomes a marsh. Eventually, marsh turns into a forest. Section 3

33. Freshwater Ecosystems: REVIEW 1. Describe some adaptations of organisms that live in moving water. 2. Compare the littoral zone with the open-water zone of a pond. 3. Describe how a swamp is different from a marsh. Section 3