ESS SL Semester 2 Term 3 (3.2, 3.3, 8.2, 4.1, 4.2, 4.3

Population Pyramids

Population Pyramids

Structures which show any measurable characteristics of the population; like sex, age, language, religion and occupation.

What does a wide base indicate?

It indicates high birth rate

What does a narrow base indicate?

Falling birth rate

What does a straight or near vertical sides indicate?

Low death rate

What does a bulge in the slope indicate?

Immigration or in-migration

What does deficits in the slope indicate?

Emigration or out-migration or age-specific or sex-specific deaths (epidemics, war)

What causes birth rates to decline?

1. Children are costly

2. The government looks after people through pensions and health services

3. More women widespread use of family planning

4. As the infant mortality rate decreases there is no need of child replacement.

Why do people want children? (High birth rates)

1. For labour

2. To look after them in old age

3. To continue family name

4. Prestige

5. To replace children who have died

What causes death rate to decline?

1. Clean water

2. Reliable food supply

3. Lower population densities

4. Better vaccination and healthcare

5. rising standards of living

What causes High death rates?

1. Lack of clean water

2. Lack of food

3. Poor hygiene and sanitation

4. Overcrowding

5. Contagious disease

6. Poverty

Crude Birth Rate

The number of births per 1000 of the population.

Whats the formula for “Crude Birth Rate”? (CBR)

Total no of births/ Total population x 1000

What are the key influences of CBR?

1. Age structure of population

2. Sex structure of population

3. Customs & family size expectations

4. Adopted population policies

Crude Death Rate (CDR)

It is the number of deaths/ 1000 people in a population

Formula for Crude Death Rate (CDR)

Total no. of deaths/ total population x 1000

What influences CDR? (10)

1. Age structure

2. Access to food/ water

3. Social Class

4. Income

5. IMR

6. Literacy

7. Child mortality

8. Occupation

9. Place of residence

10. Healthcare

Whats a poor indicator of mortality trends?

CDR

Doubling Time

Number of years it will take a population growing at a constant rate to double 70% natural increase.

Natural Rate of Increase

Rate (%) at which the population changes (CBR - CDR) / 10

• The difference between CBR and CDR and accounts for how fast populations grow.

Epidemiological Transition

The pattern of change in mortality factors during a population’s development which represents one element of the demographic transition.

Fertility Transition

the decline of fertility from high levels

Phase 1

• Primitive stability resulting from a high CBR being offset by an equally high CDR

• Basic stability is achieved when a high birth rate is balanced by an equally high death rate. Despite a life expectancy at birth of less than 30 years, the population doesn't decline because cultural factors, such as religious teachings and social pressure, encourage large families for practical benefits, power, and prestige. As a result, population growth remains close to zero.

Phase 2

• Marked by a declining CDR — the epidemiological transition. Additionally, as the fertility rate is high this results in rapid population growth.

• Death rates begin to fall, because of improved living conditions better food supplies and better health practices (eg. immunisation). The birth rate remains high and may even increase because women are healthier. Population growth is a consequence and as it takes time for social attitudes (eg. high value attached to having children) to change, birth rates remain high.

Phase 3

• Marked by declining CBR resulting in declining fertility rate, but population growth is still significant.

• Birth rates fall due to better education, family planning more career options for women and reduced infant mortality and will eventually catch up with the death rate. Population growth remains high at the beginning of this phase but eventually approaches zero.

Demographics

The study of the dynamics of population change (how populations change over time)

What are the demographic tools used for quantifying human population?

• Crude Birth Rate (CBR)

• Crude Death Rate (CDR)

• Total Fertility Rate (TFR)

• Doubling Time (DT)

• Natural Increase Rate (NIR)

Crude

Considers births to the total population without regard to the age or sex structure of the population.

Total Fertility Rate (TFR)

The average number of children a woman has during her lifetime.

Where can we find high fertility rates?

Poor countries, because they have lack of access to contraceptives and generally lower levels of female education.

What factors affect fertility rates? (9)

• Urbanization

• Importance of children in the workforce

• Children are costly

• Education/ Employment for women

• The average age of marriage

• Availability of abortion

• Availability of birth control

• Religious beliefs, traditions, and culture

• Government policies

DT (years) =

70% growth rate

Development and Transition

The total size of the world population depends on when and how much fertility declines in MEDCs.

• This will be more readily achieved by improving the educational levels of women and making contraceptives more readily available.

Population Profiles

Bar graph showing the number of people (sex separated) at each age for a given population.

How does population profile data get collected?

A questionnaire given to households

Demography

Collection, compilation, and presentation.

Rapid Growth

Slow Growth

Negative Growth

What’s the purpose of population profiles (age/ sex pyramids)?

Estimate future population growth or decline but they are not “clever”

What are the limits of population profiles?

• Do not take into account socio-economic factors

• Simply move the bars up for the necessary number of years.

Predictions can be based on what?

The natural rate of increase and not taking any developmental factors into account

• Predictions are rough and show what would happen if the current doubling time continued unabated.

UN Predictions

• High, medium, and low fertility

• Does not rely upon DT as the projections assume that the growth rate will drop slightly by 20202 and continue declining as the century progresses.

What drives conservation efforts?

Losing biodiversity

3 Direct Values for Habitat Preservation

• Food sources

• Natural Products

• Economic

Indirect Values for Habitat Preservation (6)

• Scientific and educational value

• Aesthetic — Beauty and inspiration derived from looking at diverse species and habitats.

• Ethical — Biorights, and obligations to future generations.

• Genetic — Diversity of the gene pool ensures a future variety of life. Needed for stable ecosystems.

• Social — Habitats provide homes, work, resources, and social cohesion for indigenous people.

• Ecological — Nutrient cycling, pollination, CO2 removal, and etc.

Utilitarianism

Taking the best moral action that maximizes happiness/minimizes suffering to organisms.

Intrinsic Value

The value a species has within its own right.

IGO & GO (Media)

• Statements written by officers & clerks

• Works alongside official media outlets

• Publish scientific reports

NGO (Media)

• Graphic footage to gain media attention.

• Mobilize public protests to attract attention.

• Effective use of social media to spread messages.

• Sabotage events with high media coverage.

• Publish scientific reports

IGO & GO (Speed of response)

• Considered and slow (bureaucratic)

• May go against public opinion so many views need to be considered.

NGO (Speed of Response)

• Can be rapid

• Member only join if they share opinions, so little deliberation.

• Little consideration of the status quo.

IGO & GO (Diplomatic constraints)

• Considerable — Often hindered by political disagreement (different cultural opinions and motives)

• Decisions can be politically driven rather than by best conservation strategy.

NGO (Diplomatic Constraints)

• Generally unaffected by political constraints

• Can even include illegal activity

• Driven by what is best for conservation — can lead to extreme actions.

IGO & GO (Enforcement)

• International agreements and national or regional laws can lead to prosecution.

NGO (Enforcement)

• No legal power — use of persuasion and public opinion to pressure governments.

IGO & GO (Public Image)

• Organized as businesses with concrete allocation of duties

• Cultivate an upright image based on scientific/business-like approaches.

• Lead and encourage partnerships between nations and organizations.

NGO (Public Image)

• Can be a confrontational/ radical approach to an environmental issue.

• Lead and encourage partnerships between nations and organizations to conserve and restore ecosystems and biodiversity.

IGO & GO (Political Influence)

• Enforce their decision through legislation

• Seek to ensure that decisions are applied

NGO (Political Influence)

• Serve as watchdogs (suing gov agencies and businesses who violate environmental law).

• Seek to ensure that decisions are applied

IGO & GO (Agenda)

• Provide guidelines and implement national treaties

• IGO, GO & NGO may collaborate in global, transactional scientific research projects, both may provide a forum for discussion.

NGO (Agenda)

• Use public pressure to influence national gov/ lobby gov over policies and legislation.

• Buy and manage land to protect habitat, wildlife, etc.

• IGO, GO & NGO may collaborate in global, transactional scientific research projects, both may provide a forum for discussion.

IGO & GO (Funding)

• Potentially very large budgets

• Funded by national budgets

NGO (Funding)

• Manage publicly owned lands.

• Private donations

• Can be funded by companies, governments ot political parties.

IGO & GO (Extent of influence geographically)

• Global or national in extent

• Countries can be fined/ shunned for breaking international rules

NGO (Extent of influence geographically)

• Focus more on local and/ or national information, aiming at education, producing learning materials and opportunities for schools and public

• Often relies on disruptive/ embarrassment techniques to cause change.

CITES

Convention on the International Trade of Endangered Species

WCC (World Conservation Strategy)

Commissioned by the UNEP and WWF provided the funds for its preparation and contributed to the evolution of its basic themes and structure.

CBD (Convention of Biological Diversity)

Focused on reversing trends in loss of biodiversity.

Main Approaches of Conservation

1. Species based

2. Habitat Based

3. Combination of both

How to make a conservation more successful?

• Research

• Adequate funding

• Support of the local community

What’s ‘Species Based’ Conservation?

Focuses on keystone species. Includes efforts such as captive breeding, zoos, and reintroduction.

What’s ‘Habitat Based’ Conservation?

Focus on habitats, and protect all species. Generally on-site conservation.

What’s ‘Combined’ Conservation?

Apply species-based strategies within the boundaries of habitat-based protected areas or nature reserves.

Corridors

Strips of land that link reserves together

Ecotone

Where two habitats meet near a boundary.

• Lots of species can be found in an ecotone.

Edge effect

the effect of a sudden transition between two different adjoining ecological communities on the numbers and kinds of organisms in the marginal habitat.

• This occurs at ecotones because more species are present from the two habitats (increased resources)

Protected areas

Islands within the surrounding landscape. The success and effectiveness of protected areas depend on several factors.

Criterias for consideration when designing protected areas: (5)

1. Size

2. Shape

3. Edge Effect

4. Corridors

5. Proximity to potential human influence

(SLOSS) Single Large or Several Small — Large is better than small.

• More habitats

• More species

• More niches

• More varied

• Supports larger populations

• Ideal for large mammals and apex predators

• Less edge effect

Wildlife corridor

Link of wildlife habitat, generally native vegetation, which joins two or more larger areas of similar wildlife habitat.

Corridors are critical for?

The maintenance of ecological processes including allowing for the movement of animals and the continuation of viable populations.

What are the advantages of ‘Corridor in Wildlife Reserve’?

1. Gene flow — emigration, and immigration

2. Seasonal movement

3. Reduces collisions between cars and animals

4. Reducing roads that act as barriers

What are the disadvantages of ‘Corridor in Wildlife Reserve’?

1. Invasion of exotic pests or diseases

2. Poachers can easily move from one reserve to another could become barriers to some species

3. Could have increased edge effects

Buffer Zone

Areas around conservation areas. They contain habitats that may be managed or undisturbed.

• Minimize disturbance from outside like people, agriculture, or invasion.

In situ

Conservation of species in their natural habitat

• Natural parks, natural reserves

Ex situ

Conserving species in isolation of their natural habitat

• Zoos, botanical gardens

Alternative approaches to the development of protected areas and species-based conservation such as: (7)

CITES (Conservation of International Trade in Endangered Species), captive breeding, botanical gardens, seed banks, reintroduction, flagship species, keystone species,

Captive Breeding

the process of keeping plants or animals in controlled environments, such as wildlife reserves, zoos, and botanic gardens.

• Ex situ strategy

• Cost-intensive so mostly MEDCs

Seed banks

Where seeds are stored, frozen and dry, for many years.

Flagship Species

a species selected to act as an ambassador, icon, or symbol for a defined habitat, issue, campaign, or environmental cause.

• cute, cuddly, and iconic

• Often large mammals at or near top trophic levels

• Useful for media and fundraising

  • Project integrity of the food web

  • Fulfill essential niches

  • not necessarily top trophic levels

Keystone species

a species on which other species in an ecosystem largely depend, because when it is removed, the ecosystem would change and cause other species to disappear.

• for conservation to be successful these species must be identified.

• Often engineers (e.g. beavers) create habitats.

Examples of Keystone species

• California Sea Otters

• Pisaster Starfish

• “Mangrove” trees

Strengths of species-based conservation strategies (1)

Strengths of species-based conservation strategies (2)

Weaknesses of species-based conservation strategies (1)

Weaknesses of species-based conservation strategies (2)

The Species Approach (Goal)

Protect species from premature extinction

The Species Approach (Strategies)

• Identify endangered species

• Protect their critical

The Species Approach (Tactics)

• legally protect endangered species

• Manage habitat

• Propagate endangered species in captivity

• Reintroduce species into suitable habit

The Ecosystem Approach (Goal)

Protect populations of species in their natural habitats