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Communities, Biomes, & Ecosystems. Chapter 3. Ecological Succession. Ecological Succession. Stability-the tendency to remain in a more or less constant balance due largely to interactions among organisms
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Communities, Biomes, & Ecosystems Chapter 3
Ecological Succession • Stability-the tendency to remain in a more or less constant balance due largely to interactions among organisms • Disturbance-a force that alters a biological community and usually removes organisms from it • Ecological succession-the process of community change resulting from a disturbance
Types of Succession • Primary succession: begins from an abiotic environment following a cataclysmic disturbance (volcanic eruptions or glacier melt); occurs on land where no soil exists • Secondary succession: beginning from a major disturbance, but all forms of life are not destroyed.
Stages of Succession • Pioneer: plants typically small with short lifecycles (annuals…), rapid seed dispersal, environmental stabilizers; lichens and mosses • Intermediate: plants typically longer lived, slower seed dispersal, and in woodland systems: perennials, shrubs. • Climax: plants and animal species are those associated with older, more mature ecosystem.
The Effect of Latitude on Climate • Earth is tilted on its axis causing solar radiation to strike different parts of Earth’s surface at an angle that varies throughout the year • The difference in heat distribution with latitude has important effects on Earth’s climate zones
The Role of Climate • Climate-refers to the average, year-after-year conditions of temperature and precipitation in a particular region • Weather-day-to-day condition of Earth’s atmosphere at a particular time and place • Climate is determined by • The trapping of heat by the atmosphere • The latitude • The transport of heat by winds and ocean currents • The amount of precipitation that results
Three Main Climate Zones • Polar zones-cold areas where the sun’s rays strike Earth at a very low angle • Temperate zones-sit between polar zones and the tropics, are more affected by the changing angle of the sun during the year, the climate ranges from hot to cold, depending on the season • Tropical zone-also known as the tropics, is near the equator, and receive direct or nearly direct sunlight year-round, usually warm
Heat Transport in the Biosphere • The unequal heating of Earth’s surface causes air (winds) and water (ocean currents) to circulate heat throughout the biosphere • Air rises when heated, sinks when cools forming winds; air heated near the equator rises, cooler air over the poles sinks toward the ground • Prevailing winds bring warm or cold air to a region, affecting its climate
Heat Transport in the Biosphere • Similar patterns of heating and cooling occur in Earth’s oceans • Uneven heating of Earth’s surface is a major factor driving air movements and water currents • unequal heating of surface waters, and the locations and shapes of the continents create ocean currents, river-like flow patterns in the ocean • Ocean currents transport heat energy within the biosphere • Continents and other landmasses can also affect winds and ocean currents; mountain ranges cause moist air masses to rise eventually resulting in precipitation
The Greenhouse Effect • Carbon dioxide, methane, water vapor, and other gases trap heat energy and maintain Earth’s temperature range • The natural insulation in which heat is retained by the layer of greenhouse gases is the Greenhouse effect • Greenhouse gases allow solar energy to penetrate the atmosphere in the form of sunlight
The Greenhouse Effect • Much of the sunlight that hits the surface of Earth is converted into heat energy and radiated back into the atmosphere • These same gases do not allow heat energy to pass out of the atmosphere as readily as light enters it • The gases trap heat inside Earth’s atmosphere creating a “warm” blanket causing Earth to become warmer than it should
Tundra • Northernmost biome • Permafrost is prime characteristic • Cold, long, dark winters; short, soggy summers, strong winds, low precipitation, poorly developed soils • Mosses, lichens, sedges, and short grasses • Caribou, snowy owl, arctic foxes, lemmings • Northern North America, Asia, and Europe
Taiga or Boreal Forest • Coniferous trees dominate; some deciduous trees, small, berry-bearing shrubs • Climate: • Long cold winters • Short, mild summers • Moderate precipitation, high humidity, acidic, nutrient-poor soils • Lynx, timberwolves, moose, beavers, songbirds • North America, Asia, and northern Europe
Temperate Forest • Deciduous trees dominate; contain some coniferous trees; flowering shrubs • Climate: • Year-round precipitation • Cold to moderate winters • Warm summers • Deer, black bear, bobcats, squirrels, raccoons • Eastern US, southeastern Canada, most of Europe, parts of Japan, China, and Australia
Temperate Woodland and Shrubland • Characterized by semi-arid climate • In the open woodlands, large areas of grasses, wildflowers; ex. Poppies and oak trees • Communities dominated with shrubs are also known as the “chapparal” • Fires are a constant threat because of the growth of dense, low plants that contain flammable oils • Hot, dry summers; cool, moist, winters; thin, nutrient, poor soils • Coyotes, foxes, bobcats, black-tailed deer, rabbits, squirrels • Western coasts of North and South America, areas around the Mediterranean Sea, South Africa, and Australia
Temperate Grasslands • Rich mix of grasses and under-laid by some of the world’s most fertile soils • Include plains and prairies that have been converted into agricultural fields • Periodic fires and heavy grazing by large herbivores • Warm to hot summers, cold winters, moderate, seasonal precipitation, occasional fires • Lush, perennial grasses and herbs, resistant to drought, fire, and cold • Coyotes, wolves, grizzly bears, mule deer, pronghorn antelope, rabbits, prairie dogs • Central Asia, North America, Australia, central Europe, upland plateaus of South America
Desert • Usually has an annual precipitation of less than 25 centimeters • Many undergo extreme temperature changes throughout the day • Organisms in this biome can tolerate extreme conditions • Cacti and other succulents • Mountain lions, gray foxes, bobcats, reptiles • Africa, Asia, the Middle East, US, Mexico, South America, and Australia
Tropical Savanna • Dominated with grasses with a few scattered trees • Found in tropics of central South America, large parts of eastern Africa, southern Brazil, and northern Australia • Warm temperatures, seasonal rainfall, compact soil, frequent fires set by lightning • Tall perennial grasses, sometimes drought-tolerant and fire-resistant trees or shrubs • Rich in herbivores and their predators • Lions, cheetahs, leopards, hyenas • Elephants, giraffes, antelopes, zebras, baboons, eagles
Tropical Seasonal Forest (Tropical Dry Forests) • Tropical Dry Forest: distinct wet and dry seasons; central West Africa, much of India, and Southeast Asia; shed their leaves during the long, dry season and re-leaf only during the following heavy rains or monsoons • Contain tall, deciduous trees that form a dense canopy during the wet season; drought tolerant orchids • Tigers, monkeys, elephants, Indian rhinoceros, spot-billed pelican
Tropical Rain Forests • Tropical Rain Forest: found in very humid equatorial areas such as Indonesia and the Amazon River basin in South America; rainfall is abundant and reduced rainfall lasts only a few months • Most animals are tree-dwellers (monkeys, birds, insects, snakes, bats, and frogs) • The soils are very poor because the high temperatures and rainfall lead to a rapid decomposition and recycling instead of a buildup of organic material • Most nutrients are incorporated in the living organisms
Other Land Areas • Mountain Ranges-temperature becomes colder and precipitation increases from base to summit • Polar ice caps-border the tundra are cold year-round; plants and algae are few, but includes mosses and lichens • Polar bears, seals, insects, and mites are the dominant animals • In the south polar region, Antarctica is covered by a layer of ice nearly 5 km thick in some places; penguins and marine mammals
Freshwater Ecosystems • Rivers and streams-water flows in one direction beginning at the headwater and traveling to the mouth • May also start from underground springs or from snowmelt • Sediment is material that is deposited by water, wind, or glaciers • Lakes and ponds-inland body of standing water • Oligotrophic lakes are nutrient poor and found high in the mountains • Eutrophic lakes are nutrient rich and usually found at lower latitudes
Zones of Lakes & Ponds • Littoral Zone-area closest to the shore, water is shallow and sunlight reaches the bottom; aquatic plants and algae • Limnetic Zone-open water area that is well lit and dominated by plankton • Plankton are free-floating photosynthetic autotrophs that live in freshwater or marine ecosystems; contains many species of fish in freshwater because of the availability of food, readily plankton
Zones of Lakes & Ponds • Profundal Zone-the deepest areas of a large lake, which is much colder and lower in oxygen than the other two zones: light is not abundant
Transitional Aquatic Ecosystems • Areas where land and water or saltwater and freshwater intermingle • Wetlands-areas such as marshes, swamps, and bogs that are saturated with water and support aquatic plants • Plant species include duckweed, pond lilies, cattails, sedges, mangroves, cypress, and willows • Animal species include amphibians, reptiles, birds, and mammals
Transitional Aquatic Ecosystems • Estuaries-formed where freshwater from a river or stream merges with salt water from the ocean • Are areas of transition from freshwater to saltwater and from land to sea: inhabited by a wide variety of species • Algae, seaweeds, and marsh grasses are the dominant producers • Can find mangrove trees in tropical estuaries
Intertidal Zone • Narrow band where the ocean meets land • Organisms that live here must adapt to constant change as daily tides and waves alternately submerge and expose the shore • Is further divided into vertical zones • Spray zone (dry most of the time) • High-tide zone (under water only during high tides) • Mid-tide zone (undergoes severe disruption twice a day) • Low-tide zone (covered with water unless tide is unusually low); is most populated area of the zones
Open Ocean Ecosystems • Photic – called the euphotic zone: sunlight is able to penetrate, surface seaweeds and plankton along with many species of fish, sea turtles, jellyfish, whales and dophins live here • Aphotic – light is unable to penetrate: is part of the pelagic zone which is in constant darkness and generally cold
