1. ECOSYSTEMS Glencoe Science Voyages Blue Chapter 18 How Ecosystems Change Land Environments Water Environments

2. Ecological Succession  The process of gradual change from one community of organisms to another is called ecological succession.  The changes associated with succession usually take place in a fairly predictable order and involve plants, animals and other organisms.

3. Primary Succession  Ecological succession that begins in a place that does not have soil is called primary succession.  Succession involves changes in biotic and abiotic factors which may include amount of sunlight and shade, temperature, and moisture levels.

4. Pioneer Communities  The first community of organisms to move into a new environment is called the pioneer community.  Members of pioneer communities are usually hardy organisms that survive harsh conditions.  Pioneer communities usually contain only a few species and have simple food chains.

5. Secondary Succession  Succession that begins in a place that already has soil and was once the home of other living organisms is called secondary succession.  For example, after a forest fire nothing may be left except dead trees and ash- covered soil. Gradually seeds are carried to the area by wind and birds.  As the seeds begin to grow birds and other wildlife move into the area.

6. Climax Communities  When a community has reached the final stage of ecological succession it is called a climax community.  Climax communities are complex. They may contain hundreds of thousands of species with complex feeding relationships.

7. Succession Over Time  Because primary succession begins in areas with no life at all, it can take hundreds or even thousands of years for a pioneer community to develop into a climax community.  Progressing from a pioneer community to a secondary community is a shorter process, but it still may take a century or more.

8. Factors That Determine Climate  The temperature of a region is regulated by the amount of sunlight that reaches it. The amount of sunlight is determined by its latitude and elevation. Latitude refers to distance from the equator. Due to the tilt of the Earth’s axis not all parts of the Earth receive the same amount of energy from the sun. Elevation refers to height above sea level. Earth’s atmosphere acts as insulation that traps heat. Higher elevations have a thinner atmosphere so more heat escapes into space.

9. Factors That Determine Climate (cont.)  Precipitation is the amount of water that falls to Earth in the form of rain, snow, sleet, fog, etc.  The rain shadow effect is due to warm air being forced up a mountainside, where it cools and condenses forming rain or snow. The moisture is lost on the mountain.  The region on the opposite side of the mountain receives little or no precipitation. http://staffwww.fullcoll.edu/tmorris/elements_of_ecology/images/rain_shadow.jpg

10. Land Biomes  Temperate Deciduous Forest  Tropical Rain Forest  Tundra  Taiga  Grassland  Desert Biomes: Large geographic areas with similar climates and ecosystems

11. http://www.bio.miami.edu/ecosummer/lectures/lec08_biomes.html

12. Land Biomes: Tundra  The tundra is a cold, dry, treeless region close to the poles.  The tundra receives little precipitation, but is covered with ice most of the year.  A few inches below the surface thaws each year. Below the thawed surface is permafrost.  Vegetation is mostly lichens, moss, grasses, and small shrubs.  Animal life includes reindeer, caribou, musk oxen mice, hares, hawks and snowy owls, shorebirds and songbirds.

13. Land Biomes: Taiga  The taiga is the world’s largest biome.  The taiga lies between 50° N and 60 ° N stretching across Canada, northern Europe and Asia.  The winter is long and cold, but wetter than the tundra. Precipitation is mostly snow. There is no permafrost in the taiga.  The taiga has dense forests of cone- bearing evergreen trees with lichen and moss on the forest floor.

14. Land Biomes: Temperate Deciduous Forests  Temperate forests are found both in the northern and southern hemispheres at latitudes below 50°.  Precipitation is distributed throughout the year and ranges from 75 cm to 150 cm.  Temperature ranges from below freezing to 90° F.  Forests are dominated by climax communities of deciduous trees.  As food supplies diminish in the fall and winter many animals migrate to warmer regions or hibernate to reduce their need for food.

15. Forest layers  Forests form layers of vegetation  The top of the forest is the canopy which consists of leafy branches.  Beneath the canopy is the understory, made up of shorter plants that tolerate shade.  The forest floor is dark and moist. It is home to insects, worms, and fungi.  Decomposers of plants and dead animals are found on the forest floor.

16. Land Biomes: Tropical Rain Forest  Tropical rain forest is a climax community of lush growth.  Rainfall averages 200cm to 225 cm, though some areas may receive 400 cm of rain.  Temperatures are warm and stable (77 ° F ) creating a hot humid climate much like a greenhouse.  The forest canopy may reach 30-40 m and may contain 1000 flower species and thousands of animal species.  The understory is dimly lit due to dense growth of the canopy.

17. Land Biomes: Grassland  Temperate and tropical regions that receive between 25 cm and 75 cm per year are dominated by climax communities of grasses.  Most grasslands have a dry season.  Grasslands are known by a variety of names: Prairie – N. America Steppes –Asia Veldts – Africa Pampas – S.  Extensive root systems hold the soil and provide food for grazing animals.

18. Land Biomes: Deserts  Deserts are the driest biome on earth.  Deserts receive less than 25 cm of rain each year.  The soil retains very little moisture since rain quickly drains away due to sandy soil, or evaporates rapidly.  Desert plans are usually spaced far apart and have evolved mechanisms to conserve water, such as spiny leaves and shallow roots.  Animals are more active at night during cooler temperatures.

19. Water Environments  Freshwater Biomes: Rivers and Streams Lakes and Pond  Saltwater Biomes Estuaries Seashores Open Ocean Biomes: Large geographic areas with similar climates and ecosystems

20. Water Environments Freshwater Biomes: Rivers and Streams  Fast flowing freshwater tends to have a high oxygen content as the water splashes and mixes with air.  Most of the nutrients that support life are washed into the water from the land.  Where water is deep and movement is slow nutrient levels and higher and oxygen content lower. There is also more plant growth.  Animal life may be freshwater mussles, minnows and leeches.

21. Water Environments Freshwater Biomes: Lakes and Ponds  The water of lakes and ponds has little movement.  Ponds are shallower than lakes. Sunlight can penetrate to the bottom, warming the water and promoting plant growth.  Pond environments tend to be high in nutrients.  Lakes are larger and deeper than ponds with colder temperatures toward the middle.  Sunlight penetrate only the shallower edges with most plant growth along the shoreline.

22. Water Environments Saltwater Biomes: Estuaries  The area where the river meets the ocean and contains a mixture of fresh and saltwater is called an estuary.  Salinity (salt content) changes with the amount of freshwater brought by the river and the amount of saltwater pushed in by the tides.  Estuaries are fertile, productive environments.  Estuarine organisms include algae, salt-tolerant grasses, shrimp, crabs, snails, clams, oysters, worms and fish.  Estuaries are important “nursery” areas for fish.

23. Water Environments Saltwater Biomes: Seashores  The land along the seashore is subject to tides.  The gravitational pull of the moon causes the tides to rise and fall twice each day in most parts of the world.  The intertidal zone is the portion of the seashore that is covered with water at high tide and exposed to the air during low tide.  Organisms living in the intertidal zone must be adapted to dramatic changes in temperature, moisture and salinity as well as the forces of wave action.

24. Water Environments Saltwater Biomes: Open Ocean  The ocean can be divided into life zones based on the depth to which sunlight can penetrate the water.  The lighted zone of the ocean is the upper 200m or so.  The upper 200m is the home of the plankton that make up the foundation of the food chain in the open ocean.  The dark zone is below 200m.  Animals living in the dark zone feed on the material that sinks down from the light region or they feed on each other.