Lecture: Chapter 28 - Population growth, Resource use, Sustainability

Question 1

Dilemma: Resources are running out

Answer 1

Earth’s resources are limited

Human population size si growing exponentially

Question 2

Human population

Answer 2

Overpopulation
Current estimate 6.5 billion, in 2050 9.5 billion
Huge demand on resources and space
Human conflict

Question 3

Reasons for rate of resource consumption

Answer 3

Human population size
Consumption rate (per capita)

Question 4

Natural capital

Answer 4

Includes a range of natural resources such as : Forests, grasslands, nutrients, air, water, soil, organisms

Question 5

Why do we rely on biodiversity?

Answer 5

Food
Fuel
Fiber
Medicines
Building materials

Question 6

Sustainable yield

Answer 6

Sustainable resource use requires a balance between supply and demand

Sutainable yield: Harvest rate = biological growth rate

Question 7

Yield

Answer 7

Amount of resource harvested per unit of time

Question 8

Ecosystem services

Answer 8

Processes by which the environment generates resources/natural capital

Question 9

Agriculture

Answer 9

Provides the majority of resources for humans

Replaces native habitats and diverse natural ecosystems with man-produced single crop fields (monoculture) or fields with few crops (polyculture)

Two main types:
Industrialized
Traditional

Question 10

Industrialized agriculture

Answer 10

Large energy inputs

• fossil fuels
• chemical fertilizers

Litter human and draft animal labor

Efficient, economical mechanization

Specialized machines for each crop

Mainly in developed countries in temperate zone

Question 11

Consequences of industrialized agriculture

Answer 11

Leaching
Need for fertilizers
Monoculture (pest, disease outbreaks)
Tilting soil (water erosion)

Question 12

Eutrophication

Answer 12

Nutrient enrichment.

Nutrient poor lakes with low primary production are oligotrophic

Question 13

Traditonal agriculture

Answer 13

Subsistence agriculture - for family units survival

Little energy input - mainly human and animal labor

Question 14

Shifting/swidden agriculture

Answer 14

Tropics
Clears forest for cultivation
Resulting ash is nutrient rich
Gradual decline in soil nutrient content after each harvest, need to abandon after a few harvests to allow time for fallowing

Question 15

Options to increase agricultural production

Answer 15

Increase land area of agricultural production

Increase food production per unit area

Question 16

We depend on industrialized agriculture but we need to make it sustainable. What is the solution?

Answer 16

Get benefits without negatively impacing the environment

Maintain productivity while conserving resources

Question 17

Soil conservation methods

Answer 17

Minimize wind and water erosion

• little or no tilling
• planting shrubs and trees as wind breakers

Question 18

Reduced use of pesticides

Answer 18

Control pest, disease outbreaks

• crop rotation
• use multiple crops in strips

Question 19

Alternate sources of soil nutrients

Answer 19

Alternatives to chemical fertilizers

• manure
• leguminous cover crops

Water conservation

Question 20

Forest -essential human resource

Answer 20

35% Earth’s surface

• resources from trees
• overharvesting

Forest cover decreases at a high rate

Question 21

Clear cutting

Answer 21

Large tracts of forest entirely removed

Question 22

Seed-tree / shelterwood

Answer 22

Few seed-bearing trees elft behind

Exposed land surface to erosion

Question 23

Selective cutting

Answer 23

Selected tree removal
Fewer trees remove
Accessory roads and trails still destructive

Question 24

Sustainable forestry

Answer 24

Sufficient rotation timer required for forest regeneration to levels before harvest

Question 25

Overexploitation of fisheries

Answer 25

Overfishing in the oceans has led to declines in abundance and size of top predators

Question 26

Maximum sustainable yield in fisheries

Answer 26

Under the density-dependent logistic model, the highest growth rate is at intermediate-sized populations

Question 27

How can we manage our limited resources?

Answer 27

Optimize harvest by keeping population at intermediate size