"our Global Environment" Chapter 5

Front 1

What are environmental refugees? What are some causes?

Back 1

People seeking refuge abroad due to environmental problems at home.

Hint 1

Water scarcity, depleted soils, deforestation, desertification, or environmental calamities.
pg 124

Front 2

Which biomes are more easily impaired, and take longer to recover?

Back 2

Tundra, desert, tropical rain forest, and arid grasslands.

Hint 2

pg 125

Front 3

What are some factors responsible for land degradation?

Back 3

-Overgrazing of livestock herds
-Faulty agricultural practices
-Deforestation

Hint 3

pg 125

Front 4

What is the biggest factor, and what are some causes of it?

Back 4

Overgrazing

Hint 4

-When livestock managers increase the # of livestock beyond a certain size
-When livestock managers introduce types of grazing animals foreign to a particular plant community.
pg 125

Front 5

Describe the process of land degradation from overgrazing on land and near water.

Back 5

The resulting pressures of overgrazing leads to an unraveling of the ecosystem. As plants are eaten and disappear, invader weed species take over. Since these weeds are inferior to native plants in nutritive qualities, the vitality of the herd is affected. The weeds may be trampled and are reduced in coverage, then the soil is exposed to the forces of wind & water, may be worn away, leaving a barren mud flat or rocky hillside, devoid of any plants.

Hint 5

Near water, animals trample & eat vegetation, pollute the water, and damage stream bank stability. Soil erodes, & sedimentation may result in stream beds becoming shallower, warmer, and more turbid, affecting the aquatic life.
pgs 125-126

Front 6

What is soil erosion?

Back 6

When the amount of topsoil lost exceeds that of new soil formed, then the layer of topsoil becomes thinner & thinner until it disappears, leaving only the unproductive subsoil or bare rock.

Hint 6

pg 126

Front 7

What contributes to soil erosion? Give an example.

Back 7

Poor agricultural practices

Hint 7

-When traditional practices of crop rotation were abandoned in favor of continuous cropping to increase production, erosion greatly increased because the soil surface doesn't have any plant cover during a considerable portion of the year.
-Fall plowing contributes to substantial amounts of erosion by both wind & water during winter & early spring when fields are bare.
-Compaction & crusting of soils, which depletes soil nutrients.
-Salinization or water-logging of soils from irrigation.
pgs 126-130

Front 8

What is the T-value or "T" of soil?

Back 8

The amount of organic matter (the topsoil layer)

Hint 8

pg 126

Front 9

Discuss using chemicals as an approach for areas experiencing soil erosion?

Back 9

Chemicals can replace nutrients lost through erosion, however they can't substitute the lost organic material necessary for maintaining a porous, healthy soil structure.

Hint 9

pg 126

Front 10

What is conservation tillage? What are some benefits?

Back 10

A cultivation practice that involves leaving 30% or more of the soil surface covered with the previous year's crop residue.

Hint 10

-Reduces erosion
-Increases crop yields
pgs 128-129

Front 11

What are some reasons we cut & burn woodlands? What are some consequences of the ever-increasing pace of this?

Back 11

Additional farmland, fuel, and building materials.

Hint 11

We have less area of the earth covered by forests & the quality of the remaining woodlands is decreasing.
pg 130

Front 12

What are frontier forests?

Back 12

Undisturbed, extensive areas that remain ecologically intact.

Hint 12

pg 131

Front 13

What does the rate of forest loss also affect?

Back 13

As it goes up, so do pressures on ecosystems in the form of species loss, soil erosion, even climate change.

Hint 13

pg 131

Front 14

What is deforestation?

Back 14

The permanent decline in crown cover of trees to less than 10% of its original extent.

Hint 14

pg 131

Front 15

Large areas of temperate old-growth forests have been replaced by tree plantations. Discuss the pros & cons.

Back 15

-Can reduce erosion.
-Can regenerate degraded soils.

Hint 15

-Often contain only 1 species so they are biologically less diverse.
pg 134

Front 16

What is the largest cause of deforestation? What about in poor countries?

Back 16

Population growth & its demands....but really:
The clearing of land for agriculture.

Hint 16

The gathering of wood for fuel.
pgs 134, 138

Front 17

What are some consequences of deforestation?

Back 17

(Especially in semiarid regions), the land is left bare, exposed to erosion. The productive capacity of the land rapidly decreases but also severe flooding can occur.
-Also, as the supply of fuelwood decreases, people are looking for other things to burn (leaves, grass, etc), further robbing the soil of natural fertilizers.
-Excessive erosion rates decrease the soil's water-absorbing capacity, increasing the amount of flooding & transforming the land into desert-like conditions, or producing climate change.

Hint 17

pgs 134, 136

Front 18

Discuss commercial lumbering...its causes? its consequences?

Back 18

Done to supply the increasing demands of industrial nations for furniture, plywood, and paper pulp.

Hint 18

Causes extensive soil damage & deforestation. Also, where there are indigenous forest people, their livelihood may be harmed, further increasing their impoverishment.
pg 135

Front 19

How does cattle ranching contribute to deforestation?

Back 19

When tropical soils wear out, ranchers move on, burning and cutting down trees in the next area.

Hint 19

pg 136

Front 20

How does soybean production contribute to deforestation?

Back 20

Clearing more acres for planting.

Hint 20

pg 136

Front 21

What is desertification? Where is it most likely to happen?

Back 21

Land degradation in arid, semiarid, and dry sub-humid areas, resulting from various factors including climatic variations & human activities.

Hint 21

Around water holes when nearby pastures are heavily grazes & trampled, and around towns when people denude adjacent lands in search of fuelwood.
pg 139

Front 22

What are some causes?

Back 22

(Usually) climatic fluctuations & abusive land-use practices
Also population pressures

Hint 22

pg 139

Front 23

What are wetlands?

Back 23

Ecosystems characterized by soils that are inundated or water-saturated for at least part of the year, and have water-loving plants.

Hint 23

pg 140