Download Chapter 7 Outline and Section Review Answers

Chapter 7
Climate and Biodiversity
Chapter Outline and Section Review Questions
Chapter Outline
CORE CASE STUDY: A Temperate Deciduous Forest
7-1 What Factors Influence Climate?
7-2 How Does Climate Affect the Nature and Location of Biomes?
SCIENCE FOCUS Staying Alive in the Desert
7-3 How Have Human Activities Affected the World’s Terrestrial Ecosystems?
Individuals matter: J. Michael Fay: Defender of Threatened Wild Places and National Geographic
Explorer-in-Residence
TYING IT ALL TOGETHER A Temperate Deciduous Forest and Sustainability
Key Concepts
7-1 Key factors that influence an area’s climate are incoming solar energy, the earth’s rotation, global
patterns of air and water movement, gases in the atmosphere, and the earth’s surface features.
7-2 Differences in long-term average annual precipitation and temperature lead to the formation of
tropical, temperate, and cold deserts, grasslands, and forests, and largely determine their locations.
7-3 Human activities are disrupting ecosystem and economic services provided by many of the earth’s
deserts, grasslands, forests, and mountains.
Key Questions and Case Studies
CORE CASE STUDY: A temperate deciduous forest.
The location of biomes is determined by climate. There are three major types of climate: tropical, polar
and temperate. These determine the three major biomes: forests, grasslands and deserts. When climate
changes, there is a concomitant shift in biome location.
7-1 What factors influence climate?
A. Weather is a local area’s short-term physical conditions such as temperature and precipitation.
Average temperature and average precipitation are the two major factors that determine climate
of a region, together with the related factors of latitude and elevation.
1. Climate refers to long term general patters of atmospheric conditions.
B. Global air circulation is affected by the uneven heating of the earth’s surface by solar energy,
seasonal changes in temperature and precipitation, rotation of the earth on its axis, and the
properties of air, water, and land.
1. Uneven heating of earth’s surface: the equator is heated more than the poles.
2. Rotation of the earth on its axis results in the earth moving faster beneath air masses at the
equator and slower at the poles. Belts of prevailing winds are the result.
3. Properties of air, water, and land affect global air circulation. Water evaporation sets up
cyclical convection cells. These occur both vertically and from place to place in the
troposphere. The result is an irregular distribution of climates and patterns of vegetation from
pole to pole.
C. Ocean currents influence climate by distributing heat from place to place and mixing and
distributing nutrients.
1. Differences in water density and heat create ocean currents that are warm/cold.
2. Currents redistribute absorbed solar heat from one place to another, influence vegetation and
climate near coastal regions.
3. Currents also help mix ocean waters to distribute nutrients and dissolved oxygen needed for
aquatic organisms.
4. Winds and the earth’s rotation drive the currents.
D. Water vapor, carbon dioxide, and other gases influence climate by warming the lower atmosphere
and the earth’s surface.
1. These gasses (water vapor, carbon dioxide, methane, and nitrous oxide) are known as
greenhouse gasses. They allow mostly visible light, some infrared radiation, and ultraviolet
radiation to pass through the troposphere. This natural warming is the greenhouse effect.
E. Interactions between land and oceans and disruptions of airflows by mountains and cities affect
local climates. Various topographic features can create local and regional microclimates.
1. One example of this is the rainshadow effect.
2. Bricks, asphalt, and other building materials create distinct microclimates in cities.
7-2 How does climate affect the nature and location of biomes?
A. Different climates lead to different communities of organisms, especially vegetation. Differences
in average temperature and precipitation due to global air and water circulation lead to differences
in climate.
1. Average annual precipitation, temperature, and soil type are the most important factors in
producing tropical, temperate, or polar deserts, grasslands, and forests.
2. Biomes are actually a mosaic of different biological communities.
3. Climate and vegetation vary with latitude and elevation of an area.
B. Deserts have little precipitation and little vegetation and are found in tropical, temperate, and
polar regions.
1. Tropical deserts are hot and dry most of the year with few plants, rocks, and sand.
2. Temperate deserts have high daytime temperatures in summer and low temperatures in winter,
with more rain than in tropical deserts.
3. Cold deserts have cold winters and warm summers, with low rainfall.
SCIENCE FOCUS, Staying Alive in the Desert
Plants and animals have numerous adaptations to the harsh conditions in desert environments. These
tend to revolve around avoiding heat, and absorbing or retaining the maximum amount of water.
C. Grasslands have enough precipitation to support grasses but not enough to support large stands of
trees. The three main types of grasslands are tropical, temperate, and polar (tundra).
1. Savannas are tropical grasslands with scattered trees and enormous herds of hoofed animals. a.
2. Temperate grasslands with cold winters and hot, dry summers have deep and fertile soils that
make them widely used for growing crops and grazing cattle.
3. Polar grasslands are covered with ice and snow except during a brief summer.
D. Chaparral has a moderate climate but its dense thickets of spiny shrubs are subject to periodic
fire. Chaparral, or temperate shrubland, is found in coastal areas that border deserts.
E. Forests have enough precipitation to support stands of trees and are found in tropical, temperate,
and polar regions. There are three main types of forest—tropical, temperate, and boreal (polar).
1. Tropical rain forests have heavy rainfall on most days and a rich diversity of species
occupying a variety of specialized niches in distinct layers. Tropical rain forests are near the
equator and have hot, humid conditions.
a. So far, at least half of these forests have been destroyed or disturbed by human activities.
2. Temperate deciduous forests grow in areas with moderate average temperatures, abundant
rainfall, and long, warm summers.
a. On a worldwide basis, this biome has been disturbed by human activity more than any other
terrestrial biome as a result of establishing settlements, industrialization, and urbanization.
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3. Evergreen coniferous forests or boreal forests are located in areas just south of arctic tundra
around the northern sub-arctic regions of the earth. These forests consist mostly of conebearing evergreen trees that keep their needles year-round to help the trees survive long, cold
winters.
4. Coastal areas support huge cone-bearing evergreen trees such as redwoods and Douglas fir in
a cool and moist environment. Coastal coniferous forests or temperate rain forests are located
along the western coast of Canada to northern California. Cool temperatures, abundant rain,
and dense fog are the norm.
5. Mountains are high-elevation forested islands of biodiversity and often have snow-covered
peaks that reflect solar radiation and gradually release water to lower-elevation streams and
ecosystems.
a. Mountains have important ecological roles such as habitats for endemic species,
biodiversity, and sanctuaries for animal species driven from other habitats.
b. Mountains play a major role in the hydrologic cycle.
7-3 How have we affected the world’s terrestrial ecosystems?
A. Human activities have damaged or disturbed to some extent about 62% of the world’s terrestrial
ecosystems.
B. Humans have had a number of specific harmful effects on the world’s deserts, grassland, forests,
and mountains.
Key Terms
biomes
climate
greenhouse effect
greenhouse gases
ocean currents
permafrost
rain shadow effect
weather
Suggested Answers to End of Chapter Review Questions
Review Questions
1. Core Case Study. Describe a temperate deciduous forest (Core Case Study) and explain why it serves
as an example of how differences in climate lead to the formation of different types of ecosystems.
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Temperate deciduous forests typically see warm summers, cold winters, and an abundance of
precipitation. Differences in climate, mostly from average annual precipitation and temperature,
lead to the formation of tropical (hot), temperate (moderate), and polar (cold) deserts, grasslands,
and forests.
2. Section 7-1. What is the key concept for this section? Distinguish between weather and climate.
Define ocean currents. Describe three major factors that determine how air circulates in the lower
atmosphere. Explain how varying combinations of precipitation and temperature, along with global
air circulation and ocean currents, lead to the formation of various types of forests, grasslands, and
deserts.
 Key concept: Key factors that influence an area’s climate are incoming solar energy, 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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Weather is a set of physical conditions of the lower atmosphere such as temperature,
precipitation, humidity, wind speed, cloud cover, and other factors in a given area over a period
of hours or days.
Climate is an area’s general pattern of atmospheric conditions over periods ranging from at least
three decades to thousands of years.
Heat from the sun evaporates ocean water and transfers heat from the oceans to the atmosphere,
especially near the hot equator. This evaporation of water creates giant cyclical convection cells
that circulate air, heat, and moisture both vertically and from place to place in the atmosphere.
Three major factors determine how air circulates in the lower atmosphere:
o Uneven heating of the earth’s surface by the sun
o Rotation of the earth on its axis
o Properties of air, water, and land
The earth’s air circulation patterns, prevailing winds, and configuration of continents and oceans
result in giant convection cells in which warm, moist air rises and cools, and cool, dry air sinks.
These cells lead to an irregular distribution of climates and deserts, grasslands, and forests.
3. Define and give four examples of a greenhouse gas. What is the greenhouse effect and why is it
important to the earth’s life and climate?
 Greenhouse gases include several gases in the atmosphere, including water vapor (H2O), carbon
dioxide (CO2), methane (CH4), and nitrous oxide (N2O), which absorb and release heat that
warms the atmosphere.
 The earth’s surface absorbs solar energy and transforms it to heat, which then rises into the lower
atmosphere. Some of this heat escapes into space, but some is absorbed by molecules of
greenhouse gases and emitted into the lower atmosphere. This natural warming effect of the
troposphere is called the greenhouse effect.
 The greenhouse gases and the natural greenhouse effect play an essential role in determining the
earth’s average temperatures and its climates.
4. What is the rain shadow effect and how can it lead to the formation of deserts? Why do cities tend to
have more haze and smog, higher temperatures, and lower wind speeds than the surrounding
countryside?
 The rain shadow effect is a reduction of rainfall and loss of moisture from the landscape on the
side of mountains 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 semi-arid and arid conditions on the leeward side of the mountain range and the land
beyond.
 Cities have building materials that absorb and hold heat, buildings that block wind flow, and
motor vehicles and the climate-control systems of buildings that release large quantities of heat
and pollutants, resulting in more haze and smog, higher temperatures, and lower wind speeds than
the surrounding countryside.
5. Section 7-2. What is the key concept for this section? Describe how climate and vegetation vary with
latitude and elevation. What is a biome? Explain why there are three major types of each of the major
biomes (deserts, grasslands, and forests). Explain why biomes are not uniform. Describe how climate
and vegetation vary with latitude and elevation.
 Key concept: Differences in long-term average annual precipitation and temperature lead to the
formation of tropical, temperate, and cold deserts, grasslands, and forests, and largely determine
their locations.
Climate and Terrestrial Biodiversity
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Both climate and vegetation vary with latitude and elevation. If you climb a tall mountain from its
base to its summit, you would encounter deciduous forest, coniferous forest, tundra, then
mountain ice and snow.
Biomes are large terrestrial regions, such as forests, deserts, and grasslands, with distinct climates
and certain species (especially vegetation) adapted to them.
The three major biomes are determined by the amount of precipitation.
Differences in climate, mostly from average annual precipitation and temperature, lead to the
formation of tropical (hot), temperate (moderate), and polar (cold) deserts, grasslands, and
forests.
Biomes are not uniform because of the irregular distribution of resources needed by plants and
animals.
As you climb a high mountain you experience changes in vegetation similar to that of moving
latitudinally to the north.
6. Describe how the three major types of deserts differ in their climate and vegetation. Why are desert
ecosystems fragile? How do desert plants and animals survive?
 Tropical deserts are hot and dry most of the year with few plants and a hard, windblown surface
strewn with rocks and some sand.
 Temperate deserts have high daytime temperatures in summer and low in winter and there is
more precipitation than in tropical deserts, with sparse vegetation consisting mostly of widely
dispersed, drought-resistant shrubs and cacti or other succulents adapted to the lack of water and
temperature variations.
 Cold deserts have cold winters and warm or hot summers and low precipitation, with desert
plants and animals having adaptations that help them stay cool and get enough water to survive.
 Desert ecosystems are fragile because they experience slow plant growth, low species diversity,
slow nutrient cycling, and very little water.
7. Explain how the three major types of grasslands differ in their climate and vegetation. What is a
savanna? Why have many of the world’s temperate grasslands disappeared? What is permafrost?
 Tropical grasslands like the savanna contain widely scattered clumps of trees such as acacia,
which are covered with thorns that keep some herbivores away. This biome usually has warm
temperatures year-round and alternating dry and wet seasons.
 Temperate grassland has winters that can be bitterly cold, summers that are hot and dry, and
annual precipitation that is fairly sparse and falls unevenly through the year. Most of the grasses
die and decompose each year, and organic matter accumulates to produce a deep, fertile soil.
 Cold grasslands, or arctic tundra (Russian for “marshy plain”), lie south of the Arctic polar ice
cap. During most of the year, these treeless plains are bitterly cold. Winters are long and dark,
and scant precipitation falls mostly as snow. Under the snow, this biome is carpeted with a thick,
spongy mat of low-growing plants—primarily grasses, mosses, lichens, and dwarf shrubs.
 Many of the world’s natural temperate grasslands have disappeared because their fertile soils are
useful for growing crops and grazing cattle.
 Permafrost is the underground soil in which captured water stays frozen for more than two
consecutive years.
8. Explain how the three major types of forests differ in their climate and vegetation. Why is
biodiversity so high in tropical rain forests? Why do most soils in tropical rain forests hold few plant
nutrients? Why do temperate deciduous forests typically have a thick layer of decaying litter? How do
most species of coniferous evergreen trees survive the cold winters in boreal forests? What are coastal
coniferous or temperate rain forests? What important ecological roles do mountains play?
Climate and Terrestrial Biodiversity
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Tropical rain forests are found near the equator where hot, moisture-laden air rises and dumps its
moisture; these lush forests have year-round, uniformly warm temperatures, high humidity, and
heavy rainfall almost daily.
Temperate deciduous forests grow in areas with moderate average temperatures that change
significantly with the season, supporting species such as oak, hickory, maple, poplar, and beech.
Cold forests have intense cold and drought in winter when snow blankets the ground, and trees
that take advantage of the brief summers because they need not take time to grow new needles.
Tropical rain forest life forms occupy a variety of specialized niches in distinct layers.
Stratification of specialized plant and animal niches in a tropical rain forest enables the
coexistence of a great variety of species (high species diversity).
Dropped leaves, fallen trees, and dead animals decompose quickly because of the warm, moist
conditions and the hordes of decomposers. This rapid recycling of scarce soil nutrients explains
why there is so little plant litter on the ground. Instead of being stored in the soil, about 90% of
plant nutrients released by decomposition are quickly taken up and stored by trees, vines, and
other plants.
Temperate deciduous forests have slower decomposition rates and build up a thick layer of litter.
Species in coniferous forests tend to have narrow waxy needles and are less susceptible to the
cold winter temperatures.
Coastal coniferous forests or temperate rain forests are found in scattered coastal temperate areas
that have ample rainfall or moisture from dense ocean fogs. Dense stands of large conifers once
dominated undisturbed areas of this biome along the coast of North America, from Canada to
northern California.
Mountains help to regulate the earth’s climate. Mountaintops covered with ice and snow reflect
some solar radiation back into space, which helps to cool the earth and offset global warming.
9. Section 7-3. What is the key concept for this section? About what percentage of the world’s major
terrestrial ecosystems are being degraded or used unsustainably? Summarize the ways in which
human activities have affected the world’s deserts, grasslands, forests, and mountains. How is a
warming climate likely to change the earth’s biomes?
 Key concept: Human activities are disrupting ecosystem and economic services provided by
many of the earth’s deserts, grasslands, forests, and mountains.
 About 60% of the world’s major terrestrial ecosystems are being degraded or used unsustainably.
 Ways that we have affected deserts include: large desert cities, soil destruction by off road
vehicles, soil salinization from irrigation, the depletion of groundwater, land disturbance, and
pollution from mineral extraction.
 Ways that we have affected grasslands include: conversion to cropland, release of CO2 to
atmosphere from burning grassland, overgrazing by livestock, and oil production and off-road
vehicles in arctic tundra.
 Ways that we have affected forests include: clearing for agriculture, livestock grazing, timber,
urban development, conversion of diverse forests to tree plantations, damage from off-road
vehicles, and pollution of forest streams.
 Ways that we have affected mountains include: agriculture, timber extraction, mineral extraction,
hydroelectric dams and reservoirs, increasing tourism, urban air pollution, increased ultraviolet
radiation from ozone depletion, and soil damage from off-road vehicles.
 Warming climate is likely to change the locations of earth’s major biomes.
10. What are this chapter’s three big ideas? Summarize the connections between the climate and
terrestrial ecosystems, and explain how these connections are in keeping with the three scientific
principles of sustainability (see back cover).
 The three big ideas:
Climate and Terrestrial Biodiversity
o
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Differences in climate, based mostly on long-term differences in average temperature and
precipitation, largely determine the types and locations of the earth’s deserts, grasslands,
and forests.
o The earth’s terrestrial ecosystems provide important ecosystem and economic services.
o Human activities are degrading and disrupting many of the ecosystem and economic
services provided by the earth’s terrestrial ecosystems.
The climate is driven by solar power and determines what the biodiversity in any terrestrial
system will be. Nutrients are cycled throughout these systems and the rate of cycling is generally
determined by the climate.
Climate and Terrestrial Biodiversity