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4-1 The Role of Climate What is climate? ◦ Weather is the day-to-day condition of Earth's atmosphere at a particular time and place. ◦ Climate refers to the average year-afteryear conditions of temperature and precipitation in a particular region. ◦ Organisms vary in their adaptations to climate and in their tolerance for conditions that exceed the normal range. Five factors that affect climate 1. 2. 3. 4. 5. The greenhouse effect: the trapping of heat by gases in the atmosphere keeps earth warm Latitude: the angle of the sun’s rays on that part of the earth Movement of heat all over the biosphere by air and ocean currents: warm air/water rises and cold air/water sinks driving wind and ocean currents Amount of precipitation Shape and elevation of landmasses 1. The Greenhouse Effect ◦ Our atmosphere is a natural insulating “blanket” about 12km high that maintains suitable temperatures ranges for life on earth because it traps heat. Greenhouse Gases Called GHGs Atmospheric gases that trap the heat energy of sunlight include: carbon dioxide, CO2 methane, CH4 water vapor, H2O (g) nitrous oxide, N2O The Greenhouse Sunlight Effect ◦ The natural situation in which heat is retained in Earth’s atmosphere by this layer of gases. Some heat escapes into space Greenhouse gases trap some heat Atmosphere Earth’s Surface Copyright Pearson Prentice Hall In a greenhouse, light can come in but heat can’t go out! GHGs in the atmosphere allow solar radiation to enter the biosphere but slow down the loss of heat to space. Global Warming As the concentrations of GHGs increase within the atmosphere, more infrared radiation is absorbed and less escapes directly to space, resulting in amplified warming. This is called the Enhanced Greenhouse Effect or Global Warming. Signs of Change…. Enhanced Greenhouse Effect Solar energy that has been absorbed by Earth's surface is then emitted in a different form. Since Earth is much cooler than the Sun, it emits weaker radiation with longer wavelengths, in the infrared range. Some of this infrared radiation passes through the atmosphere unimpeded, but the majority is absorbed by GHGs and then reemitted in all directions-towards space, to other GHG molecules, and back to Earth's surface. GHGs block most of the infrared radiation within the atmosphere that would otherwise escape directly into space. GHG molecules have a significant impact on Earth's climate by acting as a barrier for escaping "heat". 2. Latitude and Climate Because of differences in latitude and thus the angle of heating, Earth has different climate zones Quick Review Latitude & Longitude The Earth’s Main Climate Zones the three major climate zones depend on latitude Sunlight 90°N North Pole Arctic Circle Sunlight Most direct sunlight 66.5°N Tropic of Cancer Temperate 23.5°N Equator Tropic of Capricorn 0° Tropical 23.5°S Sunlight Temperate Antarctic Circle Sunlight Polar 66.5°S 90°S South Pole Polar Copyright Pearson Prentice Hall Earth has three main climate zones. These climate zones are caused by the unequal heating of Earth's surface. Near the equator, energy from the sun strikes Earth almost directly. Near the poles, the sun's rays strike Earth's surface at a lower angle. The same amount of solar energy is spread out over a larger area, heating the surface less than at the equator. Three Major Climate Zones Polar Zones ◦ Cold areas, near North and South Poles ◦ Sun strikes at low angles ◦ between 66.5° and 90° North and South latitudes. Temperate Zones ◦ Middle zone between polar and tropics ◦ Climate ranges between hot and cold, depending on the season Tropical Zones ◦ Near the equator ◦ Receive direct sunlight making it warm all year round ◦ between 23.5° North and 23.5° South latitudes. 3. Heat Transport in the Biosphere Unequal heating of Earth’s surface drives winds and ocean currents, which transport heat throughout the biosphere. Warm air over the equator rises, while cooler air over the poles sinks toward the ground. Cold water near the poles sinks, then flows parallel to the ocean bottom, and rises in warmer regions. Heat transport in the Biosphere Earth's winds and ocean currents interact to help produce Earth's climates. The curved paths of some currents and winds are the result of Earth's rotation. 4. Amount of Precipitation A warmer climate spurs the evaporation of water from land and sea and allows the atmosphere to hold more moisture—thus setting the stage for more extreme precipitation. 5. Elevation At higher elevations temperatures drop and precipitation increases. 4-2 What Shapes an Ecosystem? Biotic and abiotic factors determine the survival & growth of an organism & the productivity of the ecosystem where the organism lives. Biotic factors: all the living things an organism interacts with. Abiotic factors: Physical, or nonliving, factors that shape ecosystems. Include: temperature precipitation humidity wind nutrient availability soil type sunlight Habitat The area where an organism lives Includes both biotic and abiotic factors think of it as the organism’s “address” in the ecosystem Niche The full range of physical & biological conditions where organism lives and the way the organism uses those conditions. Physical conditions: include temperature Biological conditions: include place in the food web No two species can share the same niche in the same habitat BUT different species can occupy similar niches. think of it as the organism’s “occupation” in the ecosystem Interactions within communities 1. 2. 3. Competition for resources - A resource is any necessity of life, such as water, nutrients, light, food, or space. Predation – one organism feeds on another; population size often controlled by predation. Symbiosis – two species living close together SYMBIOSIS INCLUDES: 1. mutualism: both benefit 2. commensalism: one benefits, other not affected 3. parasitism: one benefits, other is harmed 1. Competition Competition occurs when organisms attempt to use an ecological resource in the same place at the same time. Direct competition in nature often results in a winner and a loser—with the losing organism failing to survive. The competitive exclusion principle: no two species can occupy the same niche in the same habitat at the same time. SYMBIOSIS Mutualism Commensalism Parasitism Ecological Succession Ecosystems are constantly changing in response to natural & human disturbances. This series of predictable changes that occurs in a community over time is called ecological succession. Sometimes, an ecosystem changes in response to an abrupt disturbance. At other times, change occurs as a more gradual response to natural fluctuations in the environment. Primary Succession Occurs on surfaces where no soil exists such as rock surfaces after volcanoes erupt or after glacial retreat The first species to populate the area are called pioneer species No soil Primary Succession Secondary Succession Occurs in response to natural events such as fires, hurricanes, or logging Soil is present. Community interactions tend to restore the ecosystem to its original condition Secondary Succession Videos Succession http://youtu.be/V49IovRSJDs Webquest Secondary Succession https://sites.google.com/site/ecologicalsuc cessionwequest/secondary-succession http://www.slideshare.net/SeanHildebrand t/ecological-succession-and-communityinteractions ECOLOGICAL SUCCESSION OF STREAMS Marine Succession after a wood fall Succession in Marine Ecosystems ◦ Succession can occur in any ecosystem, even in the permanently dark, deep ocean. ◦ In 1987, scientists documented an unusual community of organisms living on the remains of a dead whale. ◦ The community illustrates the stages in the succession of a whale-fall community. Marine Succession after a whale fall A whale dies and sinks to the ocean floor. Copyright Pearson Prentice Hall Marine Succession after a whale fall Within a year, most of the whale’s tissues have been eaten by scavengers and decomposers. Copyright Pearson Prentice Hall Ecological Succession after a whale fall The decomposition of the whale’s body enriches the surrounding sediments with nutrients. When only the skeleton remains, heterotrophic bacteria decompose oils in the whale bones. This releases compounds that serve as energy sources for chemosynthetic autotrophs. The chemosynthetic bacteria support a diverse community of organisms. Copyright Pearson Prentice Hall 4-3 THE EARTH’S BIOMES A biome is a complex of terrestrial communities that covers a large area and is characterized by certain soil and climate conditions and particular assemblages of plants and animals. Biomes and Climate The climate of a region is an important factor in determining which organisms can survive there. Within a biome, temperature and precipitation can vary over small distances. The climate in a small area that differs from the climate around it is called a microclimate. Two components of climate, temperature and precipitation, can be summarized in a graph called a climate diagram. Average Temperature (°C) Average Precipitation (mm) Biomes and Climate Copyright Pearson Prentice Hall Climate Diagrams Which month has lowest precipitation? Which month has highest precipitation? What is the average temperature & precipitation in July? Average Temperature (°C) Average Precipitation (mm) Copyright Pearson Prentice Hall The Major Biomes ◦ The world's major biomes include: tropical rain forest tropical dry forest tropical savanna desert temperate grassland temperate woodland and shrubland temperate forest northwestern coniferous forest boreal forest (taiga) tundra Copyright Pearson Prentice Hall Other Land Areas – don’t fit easily into major Biome categories Mountain Ranges ◦ Abiotic and biotic conditions vary with elevation. ◦ Temperatures become colder as you move from base to summit. ◦ The amount of precipitation increases as you move from base to summit. ◦ Plants and animals also change, adapting to the changing environment. Copyright Pearson Prentice Hall Other Land Areas – don’t fit easily into major Biome categories Polar Ice Caps ◦ The polar regions are cold all year round. ◦ In the north polar region, the Artic Ocean is covered with sea ice and a thick ice cap. ◦ Dominant organisms include mosses, lichens, polar bears, seals, insects, and mites. In the south polar region, Antarctica is covered by a layer of ice nearly 5 kilometers thick in some places. The dominant wildlife includes penguins and marine mammals. Copyright Pearson Prentice Hall 4-4 Aquatic Ecosystems Nearly three-fourths of the Earth’s surface is covered with water; only 3% is fresh water. Almost all bodies of water contain a wide variety of communities governed by biotic and abiotic factors including light, nutrient availability, and oxygen. Main Factors that govern aquatic ecosystems Depth of water (distance from the shore): determines the amount of light that organisms receive Flow: flowing-water or standing-water Temperature: warmer near the surface & affects dissolved oxygen Chemistry of the water: refers to the amount of dissolved chemical substances (nutrients and oxygen) on which life depends Flowing-Water Ecosystems Rivers, streams, creeks and brooks originate in mountains or hills and flow over land Organisms that live there are well adapted to the rate of flow Turbulent water near the source has little plant life. As the water flows downhill, sediments build up and enable plants to grow. Downstream, water may meander slowly, where turtles, beavers, and river otters live. Standing-Water Ecosystems Includes lakes and ponds Water flows in and out Water also circulates within them distributing heat, oxygen and nutrients Provides habitats for organisms such as plankton ◦ Phytoplankton: unicellular algae; the base of many aquatic food webs. ◦ Zooplankton: unicellular animals that feed on phytoplankton Freshwater Wetlands Water either covers the soil or is present near the surface at least part of the year Very productive ecosystems because they serve as breeding grounds for insects, fish, and birds. Includes ◦ Bogs – form in depressions where water collects ◦ Marshes – shallow wetlands along rivers ◦ Swamps – look like flooded forest Estuaries A type of wetland formed where river meets sea – or fresh water meets salt water. Are affected by the ocean tides. Includes salt marshes (along the coast in temperate zones) and mangrove swamps (in tropical regions). Most of the primary production (by plants, algae & bacteria) is NOT consumed by herbivores but enters the food web as detritus. Organisms that feed on detritus include clams, worms and sponges. Many young animals feed and grow in estuaries then head out to sea to mature, returning to reproduce. Marine Ecosystems The photic zone: the thin upper layer of the ocean that receives light where algae and other producers can grow. The aphotic zone: is permanently dark. Other zones are based on distance from the shore: the intertidal zone the coastal ocean the open ocean Land Marine Ecosystems 200 m 1,000 m Coastal ocean Open ocean 4,000 m 6,000 m Continental shelf Continental slope and continental rise Ocean trench 10,000 m Abyssal plain Copyright Pearson Prentice Hall Photic zone Aphotic zone Marine Ecosystems Intertidal Zone ◦ Organisms that live in the intertidal zone are exposed to regular and extreme changes in their surroundings. ◦ Competition among organisms in the rocky intertidal zone often leads to zonation, the prominent arrangement of organisms in a particular habitat in horizontal bands. Copyright Pearson Prentice Hall Adaptations in the intertidal zone Here organisms are exposed to temperature extremes, waves, wind and high and low tides. Barnacles and seaweed attach to rocks. Snails, sea urchins and sea stars cling to rocks with suckers on their feet. Marine Ecosystems Coastal Ocean ◦ Extends from the low-tide mark to the outer edge of the continental shelf. ◦ Falls within the photic zone, and photosynthesis occurs throughout its depth. ◦ Often rich in plankton and many other organisms. Copyright Pearson Prentice Hall Marine Ecosystems Coastal Ocean ◦ Kelp forests named for their dominant organism, a giant brown alga one of the most productive coastal ocean communities support a complex food web Copyright Pearson Prentice Hall Marine Ecosystems Coral Reefs ◦ Found in tropical coastal waters ◦ Named for the coral animals whose calcium carbonate skeletons make up their primary structure. ◦ An extraordinary diversity of organisms flourishes among coral reefs. ◦ Reef-building corals grow with the help of algae that live symbiotically within their tissues. Copyright Pearson Prentice Hall Marine Ecosystems Open Ocean = The Oceanic Zone ◦ Extends from the edge of the continental shelf outward. ◦ It is the largest marine zone. ◦ Most of the photosynthetic activity on Earth occurs in the photic zone of the open ocean by the smallest producers. ◦ Fish dominate the open ocean. ◦ Marine mammals must stay close to surface to breathe. Copyright Pearson Prentice Hall Marine Ecosystems Benthic Zone – the ocean floor ◦ The ocean floor contains organisms that live attached to or near the bottom; depend on food from organisms in the photic zone. ◦ These organisms are called benthos. ◦ Chemosynthetic primary producers support life without light near deep-sea vents. Copyright Pearson Prentice Hall Life in the Oceanic Zones