population and environment Flashcards
what is the size of a population influenced by
how many people the environment of that area can support
Define population distribution
pattern of where people live
Give an example of uneven population distribution
In China over 90% of the population live in the Eastern part of the country due to much of the Western area bein unhabitable due to mountains and desert
Define population density
The population of an area divided by the size of that area/ number of people per square kilometre
Where are the areas of highest population density located?
South and East Asia
What prevented population rise
Famine disease war
Why has population increased since 1950
Improvements in medicine and food production
increased life expectancy and reduced infant mortality
What three physical aspects affect populations
climate
soils
resource ditribution
describe how climate has an affect on population size
few people live in arid areas such as the Sahar, but many live in temperate climates such as the UK
Tropical and temperate climates usually have the highest population sizes and densities due to ability to produce food
How will climate change affect population size in the future
It can affect population distribution, for example in coastal areas where sea levels are rising people are moving inland or even abandoning their islands
It is also causing levels of nutrition to fall in some countries
How does soil affect population
Soil fertility determines the amount and types of food that can be produced in a region and has played a role in determining where human settlements have developed
Soil erosion can cause people to migrate to other places as agriculture becomes difficult
some examples of how soil has affected populations
Naples is built near a volcano where soil fertility is high
Bangladesh have large floodplains which are very fertile so it can support large scale agriculture and feed the large population
Describe how resource distribution can affect populations
Population growth and density is linked to availability of fresh water and other resources - most deserts have small populations because of lack of water
lack of safe water can lead to food insecurity causing populations to decrease
Places with a lot of naturally occurring food and fuel are able to support fairly large populations
Give examples of revolutions that have affected population size and distribution
neolithic revolution
industrial revolution
Describe the neolithic revolution
the development of agriculture and shift from hunting and gathering to farming and permanent settlements
this caused populations to increase as food supply become more reliable
Describe the industrial revolution and its impacts
1760-1850
rapid rise in the use of machinery and factories in developed countries and coincided with population growth
e.g. Britains population more than doubled - death rates fell because of increased food production and higher incomes so people had better diets
How has global food production changed over the last 50 years
the area of agricultural land has increased as well as technological advances such as irrigation and pesticides have made it possible to produce more food from less land
What is the pattern of global cereal production
Most is produced in N.America, China and Brazil - temperate climates and countries which have enough money to invest in agriculture
Why do East Asia and North America produce a lot of food
Climates that are good for farming
lots of investment into agriculture
Why do Central America and Africa produce relatively small amounts of food
Lack of resources and funding
large areas of land unsuitable for farmins- desert
Unsuitable climates
How has global food consumption changed
More food is being consumed worldwide as population increases and countries become more economically developed
Describe global food consumption
More developed areas like North America and Europe consume a lot as they can afford to import a large variety of foods and have a culture of cu=consumerism as well as the majority of the population having a large disposable income - up to 3539kcal
Less developed areas Such as Africa S.A and Asia consume less in sub -Saharan Africa less than 2546 kcal
How does the type of food consumed vary between countries
Meat costs more t produce than plant-based food so it makes up a bigger proportion of the diet in developed countries
meat consumption 2020
USA - 149kg per capita
Ethiopia -8.3kg per capita
What kind of systems are farms
Open systems as energy and matter can be lost or gained from the environment
Define agricultural productivity
measure of the amount of food that is produced in an area -ratio of agricultural output
What are the different types of farming
Commercial
subsistence
intensive
extensive
nomadic
Describe commercial farming
production of crops or livestock to make a profit - has a high agricultural productivity and more common in developed countries
Describe subsistence farming
When just enough food is grown to feed a family and has a lower agricultural productivity
Describe intensive farming
As much as possible is produced from the land
Capital intensive - high input of capital and low labour input
labour-intensive - uses a lot of abour
escribe extensive farming
The opposite of intensive - has a low capital and labour input and produces less food but has better welfare and less impact on the environment
Describe nomadic farming
farmers move from place to place to grow crops or graze animals on different land
What factors can affect agricultural productivity
Climate
soil
describe how climate can affect agriculture
Affects how successfully plants can grow in an area and the animals that can survive there
Some crops are adapted to certain climates such as pineapples and sub-tropical climates
some climates make it difficult to farm such as frozen ground
Describe how soil can impact agriculture
some soils are of poor quality and lack of nutrients such as desert soil
Different soils are suited to different types of farming for example some soils are too shallow or not fertile enough to grow crops so are used for grazing
Describe polar climates
mainly found above 66 latitude and experience the coldest temperatures on the planet and have very little precipitation
Arctic - North - temperature can reach below -40 and precipitation is less than 100mm per year
Antarctic - South - Temperatures can fall below -80 and the interior receives less than 50mm/year but precipitation in coastal areas in higher
Why are polar population sizes low
Agricultural productivity is low - subsistence
arable farming generally isnt possible due to ground often being frozen solid so Arctic diets are mostly meat based
Migration to leave the most extreme winters
People have adapted to cold temperatures with clothing and building methods
Describe how the climate affects development in polar regions
Low temperatures and frozen ground make it hard for people to work or construct building there
buildings also mustn’t melt permafrost
Commercial fishing only takes place where there is less ice
Most of the work is seasonal - tourism and oil
Describe arid climates
Usually receive less than 250mm of rain / year
Hot deserts occur at around 30 North and South of the equator e.g. Sahara and max temperatures can reach above 40
temperate deserts occur at higher latitudes they are cooler but still very arid
Describe population distribution in arid areas
pop. is low and there are clusters of settlements around water sources
How is the arid climate a challenge for people
agriculture is impossible in most areas because rain falls very infrequently usually in the form of heavy rainstorms leading to flash flooding and soil erosion
most farming is nomadic
Water can be drawn from oases and crops can be grown in shade so these methods allow people to settle around oases
What are some of the modern solutions to challenges of arid climates
Groundwater for irrigation can be more easily accessed by motored pups
Drip irrigation minimises evaporation
Economic development is often hindered by climate but major cities can develop if there is enough money to invest in obtaining water
What are the impacts of climate change on agriculture
Decreasing agricultural productivity due to reduced rainfall
Agricultural productivity may increase in some areas as climate and precipitation may increase and get warmer more north
May be changes to the type of crops grown
Agricultural pests and diseases may increase in some areas
What are zonal soils
fully developed soils
How are soils formed
from a combination of minerals from weathered bedrock and organic matter
How do soil and climate link
Climate determines the rate of weathering of the bedrock and the type of vegetation that grows there and its rate of decomposition
Describe the distribution of podzols
Occur in cool temperate climates in the northern hemisphere where there is more precipitation and evapotranspiration
Usually found under coniferous woodland or heather moorland
Describe the O horizon of podzols
The layer of needled from the coniferous trees or heather leaf litter
Describe the A layer of podzols
A narrow acidic layer and nutrients are leached from the Ahorizon by water
Describe the E horizon of podzols
Because of the acidity of the water travelling through the soil is more able to dissolve certain minerals such as irons - leaching of these minerals creates an e horizon formed mainly of quartz, sand and silt
Describe the B horizon of podzols
Minerals accumulate in the b horizon and and iron pan forms which is a hard continuous deposited layer of iron
why are podzols not good for agriculture
acidity and lack of nutrients means few crops are able to grow
formation of hard pan can prevent water draining away making the soil vulnerable to waterlogging making ploughing difficult and machinery sinks
Some arable farming does take place but requires treatment with lime to reduce acidity
Give the layers of soils
O - humus
A- topsoil
E- silt and sand
B- minerals from above accumulate
C- mainly broken bedrock
what is the distribution of latosols
Latosols are found under tropical rainforests
the high temperature and humidity in the tropics encourages fast chemical weathering of bedrock forming soils up to 30-40m deep
Describe the o horizon of latosols
Year round plant growth means that the O horizon is quite thick however as soon as leaf litter decomposes it turns to humus and its nutrients are absorbed by vegetation rather than soil
describe the a horizon of latosols
very thin fertile layer because humus nutrients is absorbed by vegetation rather than staying soil
Describe the e horizon of latosols
pale layer of silt and sand and other minerals that have been leached
Describe the b horizon of latosols
Rainfall is higher than evapotranspiration in rainforests causing a soil moisture surplus meaning there is a lot of leaching silicate minerals are leached out from b horizon but less soluble iron compounds are left behind giving it a red colour
How can latosols affect human activity
latosols are poor for agriculture due to their low nutrient content so once the forest is removed it has no protection from the rainfall leaching increases and it has even less nutrients
laterite horizon is hard when dry so is useful to build on
What are some factors that can make soil more vulnerable to erosion
clearing vegetation
topography
climate
land use
Why is soil erosion a threat to agriculture
it removes nutrients and reduces the soils ability to hold water
almost 30% of the worlds land has become unproductive due to soil erosion in the last 40 years
What are some management strategies to reduce soil erosion
crop rotation
windbreaks
terracing
contour ploughing
slowing down run off
define waterlogging
caused when spaces between soil spaces fill with water
what are some causes of waterlogging
hard pans blocking drainage
too much irrigation
high precipitation
What problems are caused by waterlogging
plant roots can rot
soil temperature decreases
land is hard to plough
crops may be out competed by weeds
What are some ways to manage water logging
Avoid over-watering
drain the soil using pipes
add sand to soil and change its composition so that there are more air spaces
Define salinisation
build up of salts in the soil
What are the causes of salinisation
water evaporates leaving behind salt
not enough rainfall to leach away salts
irrigation water containing salt
over - fertilising
What are the problems caused by salinisation
May be toxic to plants
can dehydrate plant
What are some ways to manage salinisation
Avoid waterlogging
only use as much water for irrigation as needed
add appropriate amount of fertiliser
Define structural deterioration
when pore spaces in soil are lost
What are the causes of structural deterioration
Use of heavy machinery
removal of vegetation as roots help maintain soil structure
salinisation causes clay particles to clump together
What are the problems caused by structural deterioration
difficult for plant roots to grow
reduced soil capacity for water
land is hard to plough
What are the ways to manage structural deterioration
Avoid compaction by moving livestock
maintain vegetation cover
adding sand to clay soils to change the structure
avoid salinisation
Define food availability
a country must provide a sufficient amount of food
fine food security
reliable access to affordable food
Define food access
People must be able to regularly obtain food
Define food quality and use
the food that people consume must be nutritious enough for them to maintain a healthy life and it must be stored and prepared in a way that is hygienic
What are the 3 different strategies to improving food production
increasing food production
increasing food access
reducing waste
How can increasing food production improve food security
Agricultural expansion
intensive farming
changing the types of food produced
technology e.g. GM crops
How can increasing food access improve food security
trade - so food can be imported to countries that dont have enough however prices must be low enough for countries to be able to afford sufficient food
improving access to markets and transport links so farmers can sell their produce easier
aid
How can reducing waste help with improving food security
educating farmers on prevention of waste - pesticide s
improving shelf life and donating to food banks to reduce post production waste
consume less
Define birth rate
number of live births/1000/year
Define death rate
number of deaths per 1000 per year
Define total fertility rate
average number of children will have when she is of reproductive age
Define infant mortality rate
Number of children out of 1000 that will die before their first birthday
Define dependency ratio
proportion of population that has to be supported by the working population
What is the DTM
Shows how population of a country changes over time through five stages showing changes in birth and death rate as well as overall population
Describe stage 1 of the DTM
birth and death rate fluctuate at a high level and the population remains stable and low
Birth rate is high due to poor family planning and education
death rate is high and life expectancy is low because of poor healthcare, sanitisation and diet leading to disease and starvation
Describe stage two of the DTM
Death rate falls but birth rate remains high and the population increases rapidly
birth rate is still high due to poor family planning and education and stays high for labour reasons
Death rate falls and life expectancy increases due to improved healthcare, sanitisation and diet