Population And Environment Flashcards
1
Q
How does climate affect population density?
A
Temperature climates are more favourable to live in,
certain types of agriculture require different climates,
Extreme climates can’t support human life
2
Q
How does soil affect population density?
A
Soil will affect the amount of and variety of crops that can be grown
3
Q
How will topography affect the population density?
A
Mountainous areas are hard to build on
4
Q
How will hazards affect the population density?
A
People are less likely to move into areas that have a hazard risk,
Old cities were built without knowledge of plate tectonics,
Hazard areas can be cheaper to live in
5
Q
Stage 1 of DTM
A
High birth rate,
High infant mortality,
High death rate,
Lack of healthcare and poor hygiene
6
Q
Stage 2 of DTM
A
High birth rate,
Low death rate,
More healthcare and hygiene
7
Q
Stage 3 of DTM
A
Lower birth rate,
Death rate continues to fall,
Socio economic development
8
Q
Stage 4 of DTM
A
Low birth rate and death rate,
Population levels are still high
9
Q
Stage 5 of DTM
A
Birth rates fall even lower (different life aspirations)
Death rate evens/ increases due to an ageing population
10
Q
Advantages of the DTM
A
Provides insight to when a country’s population has changed,
There is no time limit,
Easy to understand,
Simple to draw conclusions
11
Q
Disadvantages of the DTM
A
Some countries don’t let the population naturally change,
Knowledge of disease prevention has improved,
Model presumes countries won’t regress,
Outside impacts on population change (migration)
Doesn’t show impact on the natural environment
12
Q
Definition of overpopulation
A
When there are too many people living in an area relative to the amount of resources and technology available locally to maintain a high standard of living
Catergorised by low per capita income, high unemployment and outward migration
13
Q
Definition of underpopulation
A
This occurs when there is too little people in an area to use the resources and technology effectively
An increase in population would mean the resources are more effectively used and the standard of living improves
14
Q
Definition of optimum population
A
The theoretical population which, working with all the available resources, will produce the highest standard of living for the people of the area
This concept is dynamic; when technology improves and more resources become available which means more people can be supported
15
Q
Why are the Andes and the Himalayas sparsely populated?
A
Rugged mountains and low temperatures
16
Q
Why is Iceland sparsely populated?
A
Active volcano
17
Q
Why is Northern Canada and Russia sparsely populated?
A
Too cold to support large amounts of crops/vegetation
18
Q
Why are The Netherlands and Bangladesh densely populated?
A
Flat, lowland areas are easy to grow/build onto
19
Q
Why are the Ganges densely populated?
A
Highly fertile soil
20
Q
Why is North West Europe densely populated?
A
Areas of reliable rainfall, lots of water
21
Q
Definition of food security
A
When people have enough affordable and nutritious food to eat
22
Q
What % must food supply increase by in order to meet the demand by 2030
A
50%
23
Q
How much arable land on Earth has been lost in the last 40 years?
A
A third
24
Q
What continent does most of the worlds food come from?
A
Asia
25
Which countries are the largest producers of meat and fish?
China and India
26
Definition of double burden of malnutrition
High income countries consume more processed foods (more disposable income) which makes people fat but does not give them a nutrient rich diet
In low income countries a lack of calories and nutrients (lack of money for any food) causes starvation and malnutrition
27
Physical inputs of an agricultural system
Climate, rain, length of growth season, temperature, relief, soils and drainage
28
Human inputs in agricultural systems
Labour, rent, transport, machinery, fertiliser, seed, buildings, energy and market demand
29
Processes in an agricultural system
Jobs on the farm, ploughing, weeding, harvesting
30
Positive outputs of an agricultural system
Products, crops, animals and animal products (milk, wool, meat)
31
Negative outputs of an agricultural system
Pollution, soil erosion, eutrification, unused products
32
How are the outputs of an agricultural system used in LICs?
Consumed by the farmers and their family
33
How are the outputs of an agricultural system used in HICs?
Output profit reinvested into improvements for the farm, generally to make it more efficent
34
Physical changes to the agricultural system
Floods, disease (eg, foot and mouth)
35
Human changes to an agricultural system
Change in demand, change in market price, or change in government policy
36
Definition of sedentary farming
Permanently in one place
37
Pros of sedentary farming
Stability
38
Cons of sedentary farming
Soil can be damaged,
Can't relocate it the climate dramatically changes
39
Definition of nomadic farming
Moving, farmers move to new locations a lot
40
Pros of nomadic farming
Maintains the soil fertility
41
Cons of nomadic farming
Not stable or reliable
42
Definition of subsistence farming
Crops grown just for the farmer and his family to be able to live
43
Pros of subsistence farming
Less money to spend on food in LIC
44
Cons of subsistence farming
The family will struggle if anything goes wrong
45
Definition of commercial farming
Grown to sell
46
Pros of commercial farming
Large profits used to improve efficiency of farm
47
Cons of commercial farming
Large environmental impact
48
Definition of arable farming
Crops
49
Pros of arable farming
Large yield, making them cheaper
50
Cons of arable farming
Effected largely by climate
51
Definition of pastoral farming
Animals
52
Pros of pastoral farming
More variety of products to sell
53
Cons of pastoral farming
More costly than arable
54
Definition of mixed farming
Crops and animals
55
Pros of mixed farming
If crops fail, animals can replace the lost profits
56
Cons of mixed farming
Lots more money and labour to maintain
57
Definition of extensive farming
Low inputs of labour or capital
58
Pros of extensive farming
Lots of money can be made for little effort
59
Definition of intensive farming
High inputs of labour and capital
60
Pros of intensive farming
Large yields
61
Cons of intensive farming
Costly
62
Definition of GM farming
" Genetically modified" involves inserting and changing DNA in order to produce more desirable yield
63
Pros of GM farming
High yields of aesthetically pleasing crops which people are more likely to pay for
64
Cons of GM farming
More expensive to produce, people stop buying "wonky" crops
65
Definition of organic farming
No synthetic material or alteration
66
Cons of organic farming
More expensive
67
Why do different types of farming occur in different parts of the world?
Wealth and resources, soil and climate conditions
68
Conditions needed to grow rice
High rainfall,
High temperatures (16 - 27 C),
Alluvial soils are ideal because it retains lots of water needed to grow rice
69
Conditions needed to grow potatoes
Less water,
Lower temperatures (18 - 20C)
Lose sandy soils are ideal because they easily allow roots to grow through the soil to find water and nutrients
70
Peri-urban horticulture
Offers the urban poor a buffer against food price increases and economic upheaval,
Associated with greater dietary diversity and higher calorie availability,
50% of households are involved in UPH in Latin America
71
Causes of the Irish potato famine
Failure of the potato crop,
Disease which destroyed leaves and roots,
Between 1845 and 1849
72
Impacts of Irish potato famine
Population decrease of 2.2 million,
1 million deaths,
100,000 farmers were unable to pay rent and were evicted,
Population was half of what it was in 1920
73
Importance of the potato in Ireland
Calorie dense,
Easily grown in Irish soil,
Half of Irish population relied exclusively on potatoes,
Typical cottier family consumed around 8 pounds of potatoes per person per day
74
How did the potato blight of the potato famine occur?
Small genetic variation of plants,
A strain of water mould arrived from North America,
Cold and moist weather allowed the mould to thrive,
Destroyed potatoes between 1846 - 1849
75
How many people died in the Irish potato famine?
1 million deaths from starvation,
2 million people moved out of Ireland
76
Location of semi arid climates
Between the tropics,
Alongside desert regions,
North and South America, Africa, South Asia and Australia
77
Characteristics of semi arid climates
Extremely dry,
Distinct wet season,
25 - 50 cm of rain per year
78
Importance and type of agriculture in semi arid climates
Pastoral (sedentary and nomadic), rainfed and irrigated mixed farming,
Unreliable farming causes food insecurity and malnutrition is common,
Sheep, goats and camels
Millet, cowpea and cotton
79
Threats to semi arid climate zones
Lack of rain season,
Fires commonly destroy grass,
Decrease in rainfall,
Droughts,
Malnutrition,
Overpopulation
80
Location of Mediterranean climates
Between 30 - 45 latitude,
Parts of Europe (Italy and Greece), South Africa, West America (California)
81
Characteristics of Mediterranean climate zones
Warm and stormy winters (occasional snow),
Hot and dry summers,
50 cm rain per year
82
Characteristics of vegetation in Mediterranean climate zones
Waxy leaves, shallow roots, shrubs and thorny bushes
83
Importance and type of agriculture in Mediterranean climate zones
No pastoral farming, as there is no grazing land,
Agriculture in these areas generate tourism,
Olive trees, cork oak trees, grape vines and figs
84
Threats to Mediterranean climate zones
Growth of hotels and resorts (loss of water resources)
Wild fires (especially dangerous for cork trees which have had their cork/bark harvested)
Mediterranean Sea is warming very quickly
85
Characteristics of zonal soils
Distinct layers,
Hundreds of years to form,
Formed from weathered rock, organic material, water and air
Layered profile, defined layers and features
86
Characteristics of ferrasoils
Well drained, susceptible to erosion,
Highly weathered,
Found in humid tropics,
Flat to gently sloping land,
Low pH
87
Characteristics of podzols
Form under coniferous woodland,
Weathering and decomposition of plant material is slow,
Soils are shallow
88
Impacts of soil erosion
Decrease crop yield by 50%,
Decrease nutrients available to crops,
Less space for roots,
Plants that do grow are lower quality: misshapen, smaller and less nutritious
Plants have to have a reduced selling price, and less nutrients are consumed throughout the population
89
Effect of waterlogging on plant growth
Salinity of soil water,
Nutrient levels in soil water,
Temperature,
Frequency of waterlogging,
Stage of development
90
Definition of transient toxicities (waterlogging)
When waterlogging reduces the oxygen concentration the in root zone
91
Causes of waterlogging, and their affect
Regular rainfall; caused repeated changes in the chemical equilibrium of the soil, causes some toxic substances to be present in the soil that would be safe if it was regularly drained
92
Impact of waterlogging on plant roots
Causes root tip death,
Limits the uptake of nutrients; and causes plants to ripen too quickly
93
Impact of waterlogging of soil structure
Soil structure declines
94
Alternative ways which soil structure can decline (not waterlogging)
When trodden on frequently by livestock or driven on by machinery
95
Impacts of salinization
50% of arable land will be lost by 2050
10% of land is salt-affected
Risk to food security: Central Asia, Middle East, South America, North Africa, pacific
96
What is structural deterioration in soil?
Loss of quality and nutrients in soil,
Losses physical, chemical and biological qualities,
Reduces amount of carbon soil can store by 50 - 75%
97
How is structural deterioration in soil increased?
Human activity and heavy machinery
98
Impacts/affects of structural deterioration of soil
Soil becomes non-renewable,
Crop failure,
Impacts global warming,
Largest contributor to food insecurity
99
2 types of soil structure deterioration
l. Net reduction of organic material in the top soil
2. Compaction
100
What is salinisation?
When the soil has too much salt in it
101
How do salinisation and water logging occur?
After water evaporates out of the soil, minerals remain in the soil, then the water and salts in the high water table move upwards
102
How does high wind speeds impact soil? (And example)
First a drought causes the topsoil to become dry,
Strong winds blow away the soil
For example, the dust bowl in North America (1930s)
103
5 functions of soil
Physical stability and support,
Hydrological buffer,
Food, biodiversity and habitat
Nutrient cycling,
Filtering and buffering
104
What components make up soil texture?
Proportion of sand, silts and clay
105
Importance of soil structure/texture
Influences characteristics and workability, for farming purposes
106
Solutions to soil erosion by wind (Nigeria)
Allow cow farmers to share fields and allow people to collect manure,
Plant trees to create wind breaks,
Reduce field sizes to create more hedge breaks
107
Solutions to food insecurity caused by climate change and water issues (china)
Land levelling, minimises crops and saves water for irrigation
Irrigation, and redirecting rivers,
More farming of high value crops,
GM crops to produce high value yields,
Adapting to climate change
108
Aeroponics (increasing food supplies)
Planting crops in air or mist environment without the use of soil
109
Biotechnology (increasing food supplies)
Genetic modification of living organisms to produce useful commercial products (pest resistant or bacterial strains, etc.)
110
Hydroponics (increasing food supplies)
A method of growing plants using a mineral and nutrient rich solution in water, without soil
111
Irrigation (increasing food supplies)
Applying water to land in order to supply crops with sufficient water for growth
112
Green revolution (farming)
Combination of modern technology, traditional knowledge and an emphasis on farming, social and agro-ecological systems as well as yields, especially in poorer countries
113
Importance of measuring death rates
Assess the effectiveness of a country's health system,
Helps a country determine the focus of future public health actions
114
Top 4 causes of death in the UK (2010)
Circulatory diseases, cancers and neoplasms, respiratory diseases, digestive diseases
115
Definition of health (WHO definition)
Mentally or physically free from illness
116
Definition of HALE
Average number of years that an individual lives in full health
117
Definition of DALY
Disability adjusted life years
118
What are DALYs used for?
Suggests a persons biological age is different from their chronological age,
Intended to match organ donor's to their receivers of the "same" age
119
How to calculate DALYs
Years of life lost + years lost due to disability
120
Definition of morbidity
Prevalence of disease
121
Definition of non-communicable diseases
Mental conditions or diseases that are non-infectious or non-transmissible
Eg, cancer or Alzheimer's
122
Definition of communicable diseases
Conditions that are passed from person to person
Eg, hiv/aids or tuberculosis
More prevalent in tropical regions
123
Conditions required for malaria to spread
Spread through mosquitoes,
Require hot, wet conditions for mosquitoes to breed
124
Who is affected by malaria?
2 million deaths per year,
3.4 million people live in areas with malaria,
Poorer countries are affected more by malaria,
High risk people: young children, pregnant women, internation travelers and people with hiv/aids
125
Prevention of malaria
Mosquito nets, education, antimalarial drugs
126
Symptoms of malaria
High temperatures, shakes, muscle fatigue, kidney failure and vomiting
127
Impacts of malaria
Prevents economic growth and children can't attend school
128
How does malaria affect different areas of Kenya?
North East Kenya is too dry for mosquitoes to breed (semi arid)
Rift valley has the most amount of deaths from malaria (7843 per year)
Central Kenya has low amounts of deaths from malaria (400 per year)
129
Cause of coronary heart disease
When the heart’s blood supply is blocked
130
Risk factors of coronary heart disease
Tobacco use, alcohol use, high blood pressure, high cholesterol, obesity
131
Symptoms of coronary heart disease
Chest pain, shortness of breathe, pain throughout the body, feeling faint and nausea
132
Socio economic impacts of coronary heart disease
Cost of healthcare, cost to the government when people are unable to work, cost of treatment for side effects
133
Management strategies for coronary heart disease
Regular physical activity, prescribed medicines, healthy eating, not smoking or drinking alcohol
134
Distribution of coronary heart disease
More prevalent in high income countries because people have more disposable income to spend on risk factors
135
Definition of mortality
The state of being subjected to death
136
Stage 1 of epidemiological transition model
Age of pestilence and famine
Man moved into a more agricultural society (contact with animal waste)
Infectious diseases are more common
Most prevalent disease is small pox
137
Stage 2 of epidemiological transition
Age of receding pandemics
Began with the Industrial Revolution
More clean water, sanitary sewage, mosquito suppression and more food safety
Controlled elimination of infectious diseases like smallpox
138
Stage 3 of epidemiological transition model
Age of chronic diseases
Began in the late 20th century
More "man made" and non-infectious diseases
Common diseases; cv diseases, cancer and diabetes
Long life expectancy and long period of morbidity
139
Stage 4 of epidemiological transition model
Age of delayed degenerative diseases
Began in the 1980s
Increased life expectancy
Most common diseases include; heart diseases, stroke and cancer
Dementia and ageing diseases appear more
140
Definition of ecology
The study of interactions among organisms and their environment
141
Definition of population
All of the individuals of a species that live together in an area
142
3 key features of populations
Size, density and dispersion
143
Definition of biotic potential
The highest possible vital index of a species: when it is at its highest birth rate and lowest mortality rate
144
Definition of environmental resistance
Things which limit the growth of a population, such as, predators, disease or competition
145
Definition of density independent factors
All the species in the same ecosystem will be equally affected regardless of the population size such as; weather and natural disasters
146
Definition of density dependent factors
"Regulating factors"
Any force that affects the size of a population of living things in response to the density of the population such as; in species that live close together, disease spreads faster
147
2 models which describe population growth
1. Exponential growth
2. Logistic growth
148
Definition of exponential population growth
Has no upper limit, and populations grow very quickly
149
Definition of logistic population growth
Has a limit and approaches this limit in a sigmodial fashion
150
Phases of logistic growth
Lag phase, exponential phase, diminishing growth phase and stationary phase
151
Definition of carrying capacity
Maximum population size that can be supported by the available resources
152
Location of Easter Island
Pacific Ocean,
3500 km away from mainland Chile,
Full of Moai statues (1043)
153
Why did the population of Easter Island decrease?
(According to Jared Diamond)
The people on The Island became so obsessed with building the statues that they forgot to farming (the island fell into disrepair) and the residents resulted in eating eachother
154
Why did the population of Easter island decrease?
The Island had a terrible natural environment, which led the residents to use lithium mulch gardening
By 1877 lots of locals were riddled with disease
The Island reached its carrying capacity
155
Population characteristics of low income countries
Short life expectancy,
High infant mortality,
High death rate,
High birth rate,
High natural population increase
156
Population characteristics of high income countries
Long life expectancy,
Low infant mortality,
Low death rate,
Low birth rate,
Low natural population increase
157
Characteristics of an expansive population pyramid
Larger number in lower ages,
Each group is larger in size than the one before it,
Population growth is rapid
158
Characteristics of a constrictive population pyramid
Lower number or percentage of younger people,
Population growth is negative
159
Characteristics of a stationary population pyramid
Somewhat equal numbers of all age groups,
Smaller figures for older age groups,
Population growth is neutral
160
What does width of the base of a population pyramid determine?
A wide base indicates a high birth rate
161
What does the symmetry of a population pyramid indicate?
Asymmetry indicates the difference between the male and female population
162
What do the shape of the sides of a population pyramid indicate?
Concave sides indicate high death rate,
Convex sides indicate low birth rate
163
What do bumps in the sides of population pyramids indicate?
Irregular sides indicate demographic anomalies,
Eg, baby booms or migrant work force
164
Advantages of a youthful population
Cheap and large work force,
Demographic dividend,
Growing market for manufacturing products
165
Disadvantages of a youthful population
Strain on healthcare, education and food
Lack of available jobs,
Strain on accommodation,
Lack of jobs in the future
166
Advantages of an ageing population
Large amount of experience in the workforce,
A "grey" market for leisure and health products,
Construction boom in retirement locations
167
Disadvantages of an ageing population
Large cost of providing pensions, healthcare and sheltered housing,
More taxes needed to be paid,
Young people employed to look after the elderly,
Less exports are produced
168
Solutions to a young population
Family planning,
Industrialisation to provide jobs in manufacturing
169
Solutions for an ageing population
Abolish state pensions,
Raise retirement age,
Increase taxes,
Sell homes of the elderly to pay for retirement care
170
Definition of refugee
Someone who has settled in another country through fear of their safety in their own country
171
Definition of asylum seeker
People applying for permission to settle in another country through tear of safety or persecution in their own country
172
Definition of economic migrants
People moving in order to work and earn more money
173
Demographic implications of migrants (on host country)
Increased birth rate,
Decreased potential for an ageing population,
Retirement migration increases the proportion of the elderly
174
Social implications of migrants (on host country)
Encourages cultural tolerance,
Extend cultural experiences,
Local cultures can become diluted,
Local services could struggle to cope with new influx of people and languages
175
Economic implications of migrants (on host country)
Migrants find undesirable gaps in workforce,
More economic development,
New services and housing requirements create more jobs,
Can lead to unemployment of locals,
Remittance causes money to leak out of the country
176
Environmental implications of migrants (on host country)
More resources needed puts pressure on the environment,
New houses are built on greenfield sites,
Money generated through private companies and taxation can be put into environmental projects
177
Health implications of migrants (on host country)
More diseases are introduced,
Migrants can arrive with health issues,
Language barriers can make healthcare difficult to access,
Anxiety and depression can arise from new life
178
Political implications of migrants (on host country)
Controls on migration is required to maintain economic standards and public order,
Extremist views could resurface
179
Definition of seasonal affective disorder (SAD)
Type of depression which has a seasonal pattern, the episodes of depression generally occur at the same time each year (winter) due to the lack of sunlight exposure and shorter days
180
What causes Glasgow to be such a "sick" city?
Cold rainy weather, chronic vitamin D deficiency,
Large drinking (and subsequently, takeaway) culture
181
Characteristics of Glasgow which makes it the "sickest" city in the UK
15% more mortality than other cities of similar size,
Life expectancy is drastically different between streets,
Lowest life expectancy hasn't changed in over 100 years
182
Characteristics of blue zone communities
Extremely high life expectancy areas
Generally isolated or island communities
Only 5 in the world
183
What makes Okinawa (Japan) a blue zone community?
More socialisation,
Strong emphasis on family,
Have a sense of purpose catching/picking the food they eat,
Natural plant based diet with little red meat
184
Characteristics of the population in Tanzania (Africa)
Low income country,
Low fertility and child mortality in north east,
High fertility levels in rural areas,
44.9 million population in 2012,
Population growth of 5.5% annually
185
Causes of population decrease in Tanzania (Africa)
Lots of malaria, which leads to still-births,
Droughts causing crop failure, women are needed to focus on farm work,
Increased education and life goals for women,
Rich areas have more access to contraception
186
Causes of population increase in Tanzania (Africa)
Desired number of children is 5.3,
44% of women become mothers before age 19,
Only 27.4% of people use contraception,
Little outward migration
187
Projections for Tanzania's (Africa) population, by 2050
138 million population,
13th most populous country in the world
188
Where does ozone depletion occur?
Antarctica and Australia
189
How does ozone depletion cause skin cancer?
Less protection from harmful ultraviolet B radiation
190
What causes ozone depletion?
Chlorine and bromine (used in aerosol sprays and heavy industry)
191
Direct impacts of climate change on agricultural productivity
Change in temperature and rainfall can cause crop yield to increase by 30% by 2050,
Cultivable land could extend north as temperatures increases (eg, soya and maize)
More CO2 and sunlight can increase rate of growth for crops
192
Indirect impacts of climate change on agricultural productivity
Changes in nutritional standards and the resulting health implications
193
How do changes in nutritional standards caused by climate change affect low income countries?
Changes in staple foods will have a great impact, as food can't be imported (too expensive)
194
How do changes in nutritional standards caused by climate change affect high income countries?
There is a small impact because people have enough money to pay for nutritious food, even if is more expensive
195
Population size projection for 2050
Between 9.4 and 10 billion
196
Population size projection for 2100
Between 8.4 and 12.4 billion
197
Expected fertility rate in 2050
2.1 (currently 2.3)
198
What % of goals for sustainable development are on track? (In 2023)
12%,
More than 50% are severely off track,
30% have seen very little movement (or regressed since 2015)
199
What are the 2030 goals for sustainable development?
Successors of the millennium development goals (2000 - 2015)
17 goals to aim to be achieved by 2030 to improve life on Earth for everyone,
200
What impacts the rate of population growth?
Education,
Desire for children,
And contraception availability
201
How does population growth cause environmental degradation?
More deforestation, destruction of greenfield sites to build houses, more fossil fuel use, more food demand, more farming and cattle ranching
202
How does population growth cause economic loss?
Increased prices, lack of housing, less job availability, more demand and less resources
203
How does population growth cause social disruption?
Increased crime rates, fights for resources, less job availability, migrants can cause the rise of extremist opinions
204
3 Malthusian crises
Food shortages, famine, war and epidemics
205
What did Thomas Malthus believe?
The power of the population is greater than the power of the Earth to provide substinence for the population
206
Problems with Malthus' theories
(What didn't he consider)
Increased rate of food production, ability to access more amounts of resources, contraception development
207
Support for the Malthusian theories
Club of Rome
The "limits of growth" report predicted that economic growth could not continue indefinitely because of the limited availability of natural resources
208
What did the "limits of growth" report predict?
Pollution increases before falling in 2030,
Food per head starts to decline in early 21st century,
Rapid resource depletion in the first half of the 21st century,
Population would continue to rise until 2050 after which it will decline
209
Ester Boserup's theory on population growth
Emphasised the positive; there are more people to work and contribute ideas, pressure on agricultural systems caused inventions
210
Issues with Malthusian crises in the modern day
(demographic growth)
Required housing space surpassed all that was constructed since the beginning of mankind
211
Issues with the Malthusian crises in the modern day
(Agricultural growth)
Agricultural resources have doubled since 1960,
Grain yields have increased by 92% between 1960 and 1990
212
Types of innovations since the Malthusian theories
New class of resources which offers new economic opportunities,
Existing resources are used more effectively,
Alternative resources are used when existing ones are too expensive or scarce
213
Technological innovation and agriculture since Malthusian theories
Intensification of agriculture, new methods of fertilisation, pesticide use, irrigation, multicropping systems
214
Limits to productivity (Boserup theory)
Existing store of resources, environmental factors, limits by technology
