population and the environment

define population

the amount of people in an area e.g. the population of the world is currently 7.6 billion

list the 4 ways that population can be measured in

distribution, density, numbers, change

list physical environmental factors that affect population density

• climate

• soil

• natural resources

how does the climate affect population 

• the climate affects the health and wellbeing of the population, ultimately dictating how many people can be supported in an area.

• The climate also affects agriculture as crops need certain conditions to grow, and food is needed to support a population.

• The climate also affects the incidence of disease, as some diseases thrive in certain climates, which affects population.

how does soil affect population

• the water content, nutritional content, and overall quality of the soil affects agricultural productivity, which is important in providing food to support populations.

how do natural resources affect population

• a clean water supply is needed for hygiene, sanitation, agriculture and drinking.

• in some places where there are no means of transporting natural resources, materials have to be sourced locally. (e.g. materials for shelter and fuel).

• populations cannot be supported without access to these resources

define a development process

the process of a society advancing over time

give two examples of development processes to do with food supply

1. The Neolithic Revolution

2. The Green Revolution

what was the Neolithic Revolution

• 12,000 years ago, there was a shift from mobile hunter-gatherers to agricultural communities.

• Birth rates and fertility rates rose due to a more stable food supply

what was the Green Revolution 

• the process of using technology and more efficient farming supplies/practices in agriculture to maximise yields in the 50s and 60s. 

• the Green Revolution overall created more food, especially in developing countries, meaning a larger population can be sustained.

• an estimated 1 billion people are able to be fed as a result of the green revolution.

give an example of another societal development

The Industrial Revolution

• beginning in the mid-1700s, the industrial revolution was the transition from majorly labour-intensive industry to technology manufacturing processes, including the use of machinery, fossil fuels and factories

• the process revolutionised agriculture, the manufacture of goods, transportation, medicine and other aspects of society, making life less labour-intensive for most people.

• industrialisation caused world population growth rates to increase.

do development processes always have positive effects on population growth

no. Some societal developments are causing population growth so slow, and in some cases they are causing population to decrease.

how much is population estimated to reach by 2050

9 billion

how does population growth rates being classed as exponential give reasons for why population is increasing

it shows that population has risen rapidly within 2 centuries

what are the most populated areas

urbanised areas, as many people move for job prospects and other opportunities

how many people currently live in urban areas and how is this expected to change by 2050

55% of the population currently live in urban areas and this is expected to rise to two thirds of the population by 2050

give examples of areas that are sparsely populated

sahara, Central australia, Canada. Due to unhabitable conditions, meaning the population cannot be supported

give an example of densely populated areas

areas of Bangladesh have very fertile soil, and the floodplains are good for crops, meaning they can produce large amounts of food and support a large population.

what model explains why there has been a shift from rapid population growth in richer to countries, to rapid population growth in poorer countries (and a slowing of population growth in the richer countries)

Demographic Transition Model

how has the rate of population growth changed

• until the mid 1900s, the majority of population growth was in HICs, as there was more social and economic change concentrated in these areas. Better healthcare, better job opportunities, and better living standards accelerated birth rates and lowered death rates, causing rapid growth

• in the present day, this trend has changed. HICs have the lowest population growth rates, and in some countries the population growth rates are decreasing. this is due to reasons such as more contraception available, urbanisation and changes in society.

• in contrast, developing countries/LICs have the highest growth rates, mostly due to these countries ‘catching up’ and going through similar trends that high income countries went through in the 1900s.

• overall through, global population growth rates are slowing

give some reasons why food production has increased globally 

• an increased use in farming machinery (e.g. combine harvesters) which allows for more crops to be collected in a quicker time frame.

• increased use of other farming resources, such as herbicides and pesticides, to maximise yields

• better farming management to maximise yields and create more farmable land

how have wheat and rice production increased in Asia and Northern Africa

higher yield varieties e.g. IR8

how has maize production in Latin America and the Caribbean increased

methods of land expansion (creating more arable land)

what category of countries produces the least amount of crops

LICs

give a group of regions that have consistent high yields

• Eastern Asia, North America, Western Europe

• due to availability of resources, such as nutrients and water

• Eastern Asia receives high amounts of rainfall

give a group of regions that have little or no crop growth

• central australia, saharan africa, eastern Russia

• due to extreme environmental limitations, such as droughts and temperatures unsuitable for crop growth.

why has global food consumption increased

• there are more people

• per person they are consuming more food

what continent consumes the least calories 

Africa; over 27% of Africas population are affected by severe food insecurity 

why do HIC generally consume ore food than LICs

they have more money to import food and invest in agriculture, as well as more money per person to buy food

what continent has the highest food consumption rate

North America followed by Europe ,

give some physical inputs into an agricultural system

• climate factors- sun and rain

• soil- mineral content, saturation

• location- altitude, relief

• pollination

give some human inputs into an agricultural system

• farming machinery- maintenance and harvesting

• fertilisers and pesticides 

• seeds and livestock 

• labour 

give some processes in arable (plant) farming

• planting seeds

• tending to land

• harvesting

give some processes in pastoral farming

• tending to livestock

• breeding

• collecting produce

give some useful outputs of the agricultural system 

• food crops (cereals, fruit, veg)

• other crops (cotton, silk)

• animal produce (milk, meat)

• excess products to sell/ trade

give some losses and other outputs of an agricultural system

• losses in natural disasters, such as droughts and floods

• waste e.g. manure

• unused, wasted food

give some reusable outputs and products in an agricultural system

• profits from selling goods

• fertiliser from waste

define agricultural productivity 

the amount of useful outputs (yield) in proportion to the amount of inputs, showing the efficiency of the farm.

high productivity means high yields are being achieved through low inputs, saving time, labour and money 

what is intensive farming

• high inputs in relation to agricultural land to produce the highest possible output.

• high inputs could include a lot of labour, or high capital inputs, such as machinery, to maximise yields

what is extensive farming

• low labour and capital inputs in relation to agricultural land, thus usually producing lower outputs

what is commercial farming 

• agriculture with the intention of providing yields that can be sold commercially, making a profit 

• this type of farming is usually associated with intensive farming, as more profits can be made using this strategy

what is subsistence farming 

• self-sufficient farming, where crops are grown only to support those growing the crops family or community, with little or no profit 

how is climate change affecting agriculture

• specialised farming cannot produce high yields due to a changing climate

• the amount of arable land is decreasing (i.e. more floods, more droughts)

where are latosols located

• tropical rainforest (equatorial regions)

give features of latosols 

• deep soil profile 

• red or yellow colour due to iron and aluminium content 

• high leaching due to heavy rainfall removes soluble nutrients 

• thin humus layer- despite abundant vegetation, decomposition is rapid 

• nutrient-poor- most nutrients are stored in the biomass, not the soil 

give some human impacts to latosols

• deforestation removes nutrient source (biomass), leading to soil degredation

• slash-and-burn agriculture temporarily adds nutrients but leads to rapid leaching (the downwards movement of water through the soil takes dissolved minerals and ions with it)

where are podzols located

coniferous forest/ boreal forest

give some features of podzols

• acidic, infertile soils with distinct horizons

• dark organic matter

• eluviation zone- pale/ashy from leaching

• illuviation zone- iron/aluminium/humus accumulates

• weathered rock

podsolisation- when precipitation outweighs evapotranspiration

give some human impacts to podsols

• difficult to farm- acidity and waterlogging limit arable farming

• forestry is common- conifer plantations

• drainage and liming may be used to improve soil for agriculture

how can soil erosion take place 

• climatic factors such as flooding and heavy rainfall

• lack of trees for interceptioon

• topography

• poor irrigation

• the removal of plants/ natural intercepts or precipitation

• poor contouring 

list the 3 forms of water erosion

• sheet erosion

• rills and gullies

• riverbank erosion

what is sheet erosion

• washing away soil in a uniform manner

• heavy rainfall and flooding can cause a ‘sheet’ of water to wash over an area, especially when an area is on a slope.

what are rills and gullies 

• rills are small streams that develop by erosional flowing water

• over time, rills develop into larger ravines known as gullies. huge amounts of soil and nutrients are washed away through this type of erosion

what is riverbank erosion

• the degradation of riverbank sides, causing large sections of the bank to be eroded away

where is wind erosion most likely

• in dry climates

• the soil particles are less cohesive, meaning the top soil becomes unstable.

• ploughing and tilling can also loosen soil particles.

list the three forms of wind erosion 

creeping, saltation, suspension 

what is structural deterioration

• the loss of structure of the soil, especially the pores between soil particles that contain air

• may occur when livestock trample the soil and remove the natural spaces between particles

• removing crops from soil can disrupt the structure (roots help to stabilise)

what is water logging

• when the soil becomes oversaturated with water.

• no longer oxygen present in the soil, so plants cannot respire aerobically

• roots may rot which could stunt growth

what is salinisation 

• the increase of salt content in soil, usually causing a crust of salt on the topsoil

• it occurs when the water table rises to the surface of the soil, and then the water evaporates and leaves behind salt.

• salts are toxic to plants 

what is desertification

• where fertile land becomes dry, cracked and desert-like

• caused due to the climate- little precipitation and high temperatures dries out soils

• overgrazing and over cultivation depletes soil nutrients

give some management examples of soil problems

• efficient irrigation and drainage- stop water logging, water erosion and salinisation

• contour ploughing

• terracing

• moving livestock- ensures ground is not repeatedly trampled on and prevents overgrazing

• multiple cropping- stops certain nutrients from being overexploited

• windbreaks- limit wind erosion e.g. trees, bushes, netting

how many people globally experience chronic hunger because they do not have access to sufficient food 

1 in 10 people 

list strategies to ensuring food security

1. increasing access- e.g. through trade agreements such as trade blocs, aid and relief

2. increasing amount- new technology e.g. GM crops, high yielding varieties

3. increasing efficiency- equipment and better management, waste can be reduced

4. green revolution

discuss the green revolution

• mid 20th century

• increased use of fertilisers/pesticides, mechanisation, irrigation and development of high yielding varieties (HYVs) increases yields in areas such as India

• it has raised grain yields by 160%

• however, salinisation has been caused by irrigation

• farmers have been unable to repay loans on expensive equipment

give an area that is associated with water availability

in Egypt around the river nile 

• it has lots of water availability which can be used for the irrigation of crops e.g. cotton, rice, wheat, maize 

discuss arctic climates and food availability

• extreme climates of freezing conditions

• people must solely rely on fishing for food, as growing crops is impossible

• this has led to a total population of 4 million people across the arctic areas

discuss central australia as an extreme climate

• climate is barren, dry and hot

• crops have difficultly growing there, so population is concentrated around coastal regions.

discuss monsoon seasons in India 

• heavy rainfall leads to flooding and suffocation of crops 

• farmers grow ‘wet’ rice varieties during monsoon season, so weak monsoon rain results in crop failure of wet varieties 

• people work with the climate by growing ‘wet’ varieties in flat, fertile flood plains of the Ganges Valley

• ‘dry’ rice varieties are cultivated in the irrigated hillside terraces of Indonesia 

• even during the dry season, paddies can be reused for second rice crops, beans and lentils 

• waste from crops can be used as fodder for animals 

what is being done in Burkina Faso to reduce water erosion

• using stone lines called bunds

• stones are arranged in lines across the contour, which slows down runoff of water and allows deposition of nutrient rich water

discuss the green revolution in Mexico

• Mexico tripled its wheat yields in the first two decades of the program

• by the 1960s, Mexico was producing enough wheat and maize to become self sufficient

• this meant it was able to become a net exporter of wheat, boosting the country economy.