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Climate and Terrestrial Biodiversity
Chapter 7
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The Earth Has Many Different Climates
Weather –local areas short term temperature, precipitation, humidity, wind speed, cloud cover and other physical conditions of the lower atmosphere Climate – general atmospheric conditions measured over a long period of time
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What Factors Influence Climate?
An area's climate is determined mostly by solar radiation, the earth’s rotation, global patterns of air and water movement, gases in the atmosphere, and the earth’s surface features.
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Air circulation in lower atmosphere due to
Uneven heating of the earth’s surface by the sun Rotation of the earth on its axis Properties of air, water, and land
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Connections between Wind, Climate, and Biomes
Indirect form of solar energy, part of the earth’s circulatory system for heat, moisture, plant nutrients, soil particles and long lived air pollutants Dust blown from West Africa – soil nutrients in Amazonian rain forests, toxic air pollutants in the US
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The Earth Has Many Different Climates
Prevailing winds blowing over the oceans produce mass movements of water called currents. Driven by prevaining winds and the earth’s rotation, the major oceancurrents redistribute heat from the sun from place to place., thereby influencing climate and vegetation.
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Redistribution of heat from the sun
Global Air Circulation Currents Prevailing winds Earth’s rotation Redistribution of heat from the sun 60°N Cold deserts Air cools and descends at lower latitudes. Westerlies Forests 30°N Northeast trades Hot deserts Warm air rises and moves toward the poles. Forests 0° Solar energy Equator Air cools and descends at lower latitudes. Southeast trades Hot deserts 30°S The highest solar energy input is at the equator. Figure 7.3 Global air circulation. The largest input of solar energy occurs at the equator. As this air is heated it rises and moves toward the poles. However, the earth’s rotation deflects the movement of the air over different parts of the earth. This creates global patterns of prevailing winds that help distribute heat and moisture in the atmosphere. Westerlies Forests Cold deserts 60°S Fig. 7-3, p. 142
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Energy Transfer by Convection in the Atmosphere
LOW PRESSURE HIGH PRESSURE Heat released radiates to space Condensation and precipitation Cool, dry air Falls, is compressed, warms Rises, expands, cools Warm, dry air Hot, wet air Figure 7.4 Energy transfer by convection in the atmosphere. Convection occurs when hot and wet warm air rises, cools, and releases heat and moisture as precipitation (right side). Then the denser cool, dry air sinks, gets warmer, and picks up moisture as it flows across the earth’s surface to begin the cycle again. Flows toward low pressure, picks up moisture and heat HIGH PRESSURE LOW PRESSURE Moist surface warmed by sun Fig. 7-4, p. 143
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Oceans absorb heat from the earth’s circulation patterns : most of this heat is absorbed in tropical waters, which receive most of the sun’s heat Heat and differences in water density (mass/unit volume) create warm an cold ocean currents. Prevailing winds and irregularly shaped continents interrupt these currents and cause them to flow in roughly circular patterns between the continents Clockwise – northern hemisphere Anti clockwise – southern hemisphere
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High density cold waters sinks and flows beneath warmer and less dense sea water
Creates a connected loop of deep and shallow ocean currents which act like a giant conveyor belt Transfers warm and cold water between the tropics and the poles Ocean currents are affected by winds in the atmosphere and heat from the ocean affects atmospheric circulation
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Connected Deep and Shallow ocean currents
Warm, less salty, shallow current Figure 7.5 Connected deep and shallow ocean currents. A connected loop of shallow and deep ocean currents transports warm and cool water to various parts of the earth. This loop, which rises in some areas and falls in others, results when ocean water in the North Atlantic near Iceland is dense enough (because of its salt content and cold temperature) to sink to the ocean bottom, flow southward, and then move eastward to well up in the warmer Pacific. A shallower return current aided by winds then brings warmer, less salty—and thus less dense—water to the Atlantic. This water can cool and sink to begin this extremely slow cycle again. Question: How do you think this loop affects the climates of the coastal areas around it? Cold, salty, deep current Connected Deep and Shallow ocean currents Fig. 7-5, p. 143
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Global Air Circulation, Ocean Currents, and Biomes
Moist air rises, cools, and releases moisture as rain Polar cap Arctic tundra Evergreen coniferous forest Global Air Circulation, Ocean Currents, and Biomes 60° Temperate deciduous forest and grassland Desert 30° Tropical deciduous forest Equator 0° Tropical rain forest Tropical deciduous forest 30° Desert Figure 7.6 Global air circulation, ocean currents, and biomes. Heat and moisture are distributed over the earth’s surface via six giant convection cells (like the one in Figure 7-4) at different latitudes. The resulting uneven distribution of heat and moisture over the planet’s surface leads to the forests, grasslands, and deserts that make up the earth’s terrestrial biomes. Temperate deciduous forest and grassland 6 giant convection cells moist air rises ,cool dry air sinks 60° Polar cap Fig. 7-6, p. 144
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Greenhouse Gases Warm the Lower Atmosphere
H2O allow mostly visible light and some infra red CO2 radiation and some UV radiation from the sun CH4 to pass through the atmosphere N2O Greenhouse effect – long wave length infra red radiation (heat) rises to the lower atmosphere Human-enhanced global warming – burning fossil fuels, clearing forests Allow visible light , infra red and UV radiation from the sun to pass through the atmosphere
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Flow of Energy to and from the Earth
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The Earth’s Surface Features Affect Local Climates
Heat is absorbed and released more slowly by water than by land. Creates land and sea breezes World’s oceans and large lakes moderate weather and climate Effect of earth’s surface features Mountains-interrupt flow of prevailing winds and movement of storms Rain shadow effect Cities -Microclimates bricks, concrete, asphalt absorb and hold heat and buildings block wind flow. Cars release large amount of pollutants. More haze and smog, higher temperatures and lower wind speeds
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Rain Shadow Effect Prevailing winds pick up moisture from an ocean.
On the windward side of a mountain range, air rises, cools, and releases moisture. On the leeward side of the mountain range, air descends, warms, and releases little moisture. Figure 7.7 The rain shadow effect is a reduction of rainfall and loss of moisture from the landscape on the side of a mountain facing away from prevailing surface winds. Warm, moist air in onshore winds loses most of its moisture as rain and snow on the windward slopes of a mountain range. This leads to semiarid and arid conditions on the leeward side of the mountain range and the land beyond. The Mojave Desert in the U.S. state of California and Asia’s Gobi Desert are both produced by this effect. Rain Shadow Effect Fig. 7-7, p. 145
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How Does Climate Affect the Nature and Locations of Biomes?
Differences in average annual precipitation and temperature lead to the formation of tropical, temperate, and cold deserts, grasslands, and forests, and largely determine their locations.
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Climate Affects Where Organisms Can Live
Major biomes – large terrestrial regions characterized by similar climate, soil, plants and animals. Mosaic of patches each with some basic similarities but different biological communities Latitude and elevation Annual precipitation Temperature –tropical, temperate, polar
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The Earth’s Major Biomes
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Effects of Elevation and Latitude on Climate and Biomes
Mountain ice and snow Tundra (herbs, lichens, mosses) Coniferous Forest Deciduous Forest Latitude Tropical Forest Figure 7.9 Generalized effects of elevation (left) and latitude (right) on climate and biomes. Parallel changes in vegetation type occur when we travel from the equator to the poles or from lowlands to mountaintops. Question: How might the components of the left diagram change as the earth warms during this century? Explain. Tropical Forest Deciduous Forest Coniferous Forest Tundra (herbs, lichens, mosses) Polar ice and snow Fig. 7-9, p. 147
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Decreasing temperature Decreasing precipitation
Cold Polar Tundra Subpolar Temperate Coniferous forest Decreasing temperature Desert Deciduous forest Grassland Tropical Chaparral Hot Figure 7.10 Natural capital: average precipitation and average temperature, acting together as limiting factors over a long time, help to determine the type of desert, grassland, or forest biome in a particular area. Although each actual situation is much more complex, this simplified diagram explains how climate helps to determine the types and amounts of natural vegetation found in an area left undisturbed by human activities. (Used by permission of Macmillan Publishing Company, from Derek Elsom, The Earth, New York: Macmillan, Copyright © 1992 by Marshall Editions Developments Limited). Desert Wet Rain forest Savanna Dry Tropical seasonal forest Scrubland Decreasing precipitation Fig. 7-10, p. 147
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There Are Three Major Types of Deserts
Tropical deserts Temperate deserts Cold deserts Fragile ecosystem Slow plant growth Low species diversity Slow nutrient recycling Lack of water
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Climate Graphs of Three Types of Deserts
Figure 7.11 Climate graphs showing typical variations in annual temperature (red) and precipitation (blue) in tropical, temperate, and cold deserts. Top photo: a popular (but destructive) SUV rodeo in United Arab Emirates (tropical desert). Center photo: saguaro cactus in the U.S. state of Arizona (temperate desert). Bottom photo: a Bactrian camel in Mongolia’s Gobi Desert (cold desert). Question: What month of the year has the highest temperature and the lowest rainfall for each of the three types of deserts? Stepped Art Fig. 7-11, p. 149
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There Are Three Major Types of Grasslands
Tropical – savanna : grazing animals, browsing animals Temperate – tall grass prairie and short grass prairie- Cold (arctic tundra) – permafrost, very fragile biome
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Climate Graphs of Tropical, Temperate, and Cold Grasslands
Figure 7.12 Climate graphs showing typical variations in annual temperature (red) and precipitation (blue) in tropical, temperate, and cold (arctic tundra) grassland. Top photo: wildebeests grazing on a savanna in Maasai Mara National Park in Kenya, Africa (tropical grassland). Center photo: wildflowers in bloom on a prairie near East Glacier Park in the U.S. state of Montana (temperate grassland). Bottom photo: arctic tundra (cold grassland) in autumn in front of the Alaska Range, Alaska (USA). Question: What month of the year has the highest temperature and the lowest rainfall for each of the three types of grassland? Stepped Art Fig. 7-12, p. 151
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Monoculture Crop Replacing Biologically Diverse Temperate Grassland
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Temperate Shrubland: Nice Climate, Risky Place to Live
Chaparral Near the sea: nice climate Prone to fires in the dry season
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Chaparral Vegetation in Utah, U.S.
Figure 7.14 Chaparral vegetation in the U.S. state of Utah and a typical climate graph. Stepped Art Fig. 7-14, p. 152
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There Are Three Major Types of Forests
Tropical rain forests Temperature and moisture Stratification of specialized plant and animal niches Little wind: significance Rapid recycling of scarce soil nutrients Impact of human activities
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There Are Three Major Types of Forests
Temperate deciduous forests Temperature and moisture Broad-leaf trees Slow rate of decomposition: significance Impact of human activities
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There Are Three Major Types of Forests
Evergreen coniferous forests: boreal and taigas Temperature and moisture Few species of cone: bearing trees Slow decomposition: significance Coastal coniferous forest Temperate rain forests
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Climate Graphs of Tropical, Temperate, and Cold Forests
Figure 7.15 Climate graphs showing typical variations in annual temperature (red) and precipitation (blue) in tropical, temperate, and cold (northern coniferous and boreal) forests. Top photo: the closed canopy of a tropical rain forest in the western Congo Basin of Gabon, Africa. Middle photo: a temperate deciduous forest in the U.S. state of Rhode Island during the fall. (Photo 4 in the Detailed Contents shows this same area of forest during winter.) Bottom photo: a northern coniferous forest in the Malheur National Forest and Strawberry Mountain Wilderness in the U.S. state of Oregon. Question: What month of the year has the highest temperature and the lowest rainfall for each of the three types of forest? Stepped Art Fig. 7-15, p. 154
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Tropical Rain Forest Ocelot Blue and gold macaw Harpy eagle
Squirrel monkeys Climbing monstera palm Katydid Green tree snake Slaty-tailed trogon Tree frog Figure 7.16 Some components and interactions in a tropical rain forest ecosystem. When these organisms die, decomposers break down their organic matter into minerals that plants use. Colored arrows indicate transfers of matter and energy between producers; primary consumers (herbivores); secondary, or higher-level, consumers (carnivores); and decomposers. Organisms are not drawn to scale. See an animation based on this figure at CengageNOW. Ants Bacteria Bromeliad Fungi Producer to primary consumer Primary to secondary consumer Secondary to higher-level consumer All producers and consumers to decomposers Fig. 7-16, p. 155
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Black-crowned antpitta
Stratification 45 Harpy eagle Emergent layer 40 35 Toco toucan Canopy 30 25 Height (meters) 20 Under story Wooly opossum 15 Figure 7.17 Stratification of specialized plant and animal niches in a tropical rain forest. Filling such specialized niches enables species to avoid or minimize competition for resources and results in the coexistence of a great variety of species. 10 Brazilian tapir Shrub layer 5 Black-crowned antpitta Ground layer Fig. 7-17, p. 156
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Temperate Rain Forest in Washington State, U.S.
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Mountains Play Important Ecological Roles
Majority of the world’s forests Habitats for endemic species Help regulate the earth’s climate – snow and ice covers reflect solar radiation back. Cool earth and off set global warming Can affect sea levels by storing and releasing water in glacial ice. Warmer earth adds water by melting of glaciers Major storehouses of water Role in hydrologic cycle
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Mount Rainier National Park in Washington State, U.S.
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How Have We Affected the Word’s Terrestrial Ecosystems?
In many areas, human activities are impairing ecological and economic services provided by the earth’s deserts, grasslands, forests, and mountains.
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Humans Have Disturbed Most of the Earth’s Lands
Deserts Grasslands Forests Mountains
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NATURAL CAPITAL DEGRADATION
Major Human Impacts on Terrestrial Ecosystems Deserts Soil salinization from irrigation Depletion of groundwater Land disturbance and pollution from mineral extraction Grasslands Conversion to cropland Release of CO2 to atmosphere from burning grassland Overgrazing by livestock Oil production and off-road vehicles in arctic tundra Forests Clearing for agriculture, livestock grazing, timber, and urban development Conversion of diverse forests to tree plantations Damage from off-road vehicles Pollution of forest streams Mountains Agriculture Timber extraction Hydroelectric dams and reservoirs Mineral extraction Increasing tourism Urban air pollution Increased ultraviolet radiation from ozone depletion Soil damage from off-road vehicles Large desert cities Figure 7.20 Major human impacts on the world’s deserts, grasslands, forests, and mountains. Question: Which two of the impacts on each of these biomes do you think are the most harmful? Soil destruction by off-road vehicles Stepped Art Fig. 7-20, p. 158
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