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Population and the Environment

Global Population

  • Environmental conditions mean populations are not evenly spread. Distribution is the pattern of the population, 90% of China live near east coast.
  • Density is population divided by size of area people per km Bangladesh = 1200 per km2 whereas Libya = 4 per km2.
  • Global population has risen rapidly from 1800, 1 billion to 2017, 7.5 billion. Until 1950s population growth was in HICs, but now LICs’ life expectancy has increased, and death rates decreased.
  • Urban increasing faster than rural, so populations becoming less evenly distributed. Exponential growth means the population is rapidly growing at constant rate.

 

Physical Factors Affecting Population

  • Climate (sparse) – low annual rainfall, high humidity and artic temperatures.
  • Climate (dense) – reliable rainfall, no extreme temperatures, lengthy growing season.
  • Soils (sparse) – permafrost, leached/infertile, thin, overgrazed.
  • Soils (dense) – rich humus, alluvial (floodplains).
  • Resources (sparse) – lacking fuel/valuable minerals, restricted access to fresh water.
  • Resources (dense) – concentrations of valuable minerals/fuel, availability of water.

 

Food Production and Consumption

  • Food production has increased due to technological advances, ‘Green Revolution’ – pesticides, equipment, irrigation techniques etc.
  • Global food production is unevenly distributed. East Asia and N. America produce more due to good climate and investments in farming. Central America and Africa produce less due to lack of resource, unsuitable land and climates.
  • Global food consumption is also unevenly distributed. HICs consume a lot due to higher income, importing power and consumer culture 2600-3,800 kcal per day. LICs consume less as they can’t afford as much.

 

Agricultural Productivity and Systems

  • Agricultural productivity – ratio of inputs labour and capital to outputs food produced.
  • Commercial – growing crops/ rearing livestock to make a profit.
  • Subsistence – just enough produced to feed farmer’s family, common in Africa.
  • Intensive – farm size is small compared to large amount of inputs as labour and capital required.
  • Capitol-intensive – high inputs of money and low labour. May use fertilisers, pesticides, and labour-saving machinery.
  • Labour-intensive – doesn’t involve much capital but a lot of labour.
  • Extensive – farm size is large compared to inputs such as small numbers of livestock grazing on large areas of land, less food but less impact on environment, better animal welfare.
  • Agribusiness – large corporate organisations run farms for profit maximisation.

 

 

 

 

Polar Climates

  • Tundra and icecap regions cover more than 20% of earth. Populations in arctic regions is under 4 million – climate can’t support large climate. Winter periods intensely cold (below –40oC) with little precipitation bar snow and strong winds.
  • Tundra regions have permanently frozen ground called permafrost. Agricultural productivity is low, mainly subsistence farming. Arable farming is almost impossible as plants cannot survive.
  • Diets mostly meat-based: reindeer, fish, small mammals. Reindeer migrate south in winter and some native nomadic groups follow to retain a stable food source.
  • Artificial arable farming is done by thawing permafrost and enriching soil with manure and molasses.

 

Tropical Climates

  • Half the global population live in tropical monsoon climates, six of the most populated countries: China, India, Bangladesh, Pakistan, Japan and Indonesia.
  • Summer season – hot, wet winds originating from equatorial ocean blow in from southwest resulting in intense rainfall.
  • Winter season – cool, dry winds are blown in from the north and northeast of the continent to the south and the ocean, sometimes causing drought.
  • Rice is the staple food high in carbohydrate, fibre and vegetable protein. Farming is intensive, using all available arable land to cultivate crops whether it be floodplains or steep relief terraces.

 

Climate Change

  • Climates becoming warmer and more humid. May increase the range of habitats for pests like mosquitoes and flies and diseases that contaminate crops.
  • Water scarcity increases, decreasing water supply for agricultural practices.
  • Longer growing seasons in temperate regions.
  • Decreased yields due to climate change means price will rise. Fall in cereal and meat consumption.
  • Increased need for GM new climate tolerant crop varieties.

 

Soil Functions

  • Cycling nutrients – carbon, nitrogen, phosphorous etc are stored and transformed in soil.
  • Regulating water – helps control where rain, snowmelt and irrigation water goes.
  • Sustaining plant/animal life – diversity and productivity of living things depends on soil.
  • Filtering pollutants – minerals and microbes in the soil degrade, immobilise and detoxify.
  • Stability and support – provide structure for plants to grow in.

 

Classification

  • Zonal – mature soils, reflect climatic conditions and surrounding vegetation, dynamic equilibrium with parent material, plant matter and climate. Have clear and distinct profiles.
  • Azonal – immature and skeletal soil with poorly developed profiles.
  • Zonal Soils – Podzols:
  • Occur in temperate climates where there is more precipitation than evapotranspiration; in northern hemisphere; usually coniferous woodland or moorland – organic layer of needles or leaf litter.
  • A – acidic top soil with high organic matter content.
  • E – leaching of minerals and compounds from A creates pale layer of quartz, sand and silt.
  • B – reddish-brown layer of accumulated minerals, ‘hard pan’ of deposited iron.
  • Arable farming is difficult due to acidity and lack of nutrients. ‘Hard pan’ can prevent water draining, making soil vulnerable to waterlogging which sinks machinery and damages crops. Extensive artificial fertilisation to reduce acidity. Forestry common as trees grow well.

 

Zonal Soils – Latosols

  • Occur in tropical rainforests; high humidity and temperature; rainfall exceeds evapotranspiration meaning more leaching.
  • – year-round plant growth results in thick horizon.
  • A – when leaf litter decomposes, nutrients are absorbed by plants before contributing to soil content, resulting in a thin horizon.
  • B – leaching of silicate minerals but less soluble iron compounds remain giving it red colour.
  • Poor agricultural potential due to low nutrient content in ‘fertile’ A horizon. Deforestation means soil is exposed to weathering by heavy rainfall, leaching the nutrients further. ‘Slash and burn’ practises clear small areas for growing crops at a time, adding nutrients to soil by burning and left to fully recover during next growing season.

 

Soil Water Erosion

  • Sheet erosion – rain loosens topsoil, overland flow transports layer of soil away.
  • Rill erosion – mini streams form on soil when soil moisture content has exceeded capacity.
  • Gully erosion – rills erode into larger ditches which are hazardous for farming machinery.
  • Soil Wind Erosion:
  • Abrasion and attrition – wind-suspended particles fall to ground and impact causes erosion.
  • Suspension – small particles lifted by wind and carried away from site.
  • Saltation – particles are lifted by wind and scattered, bouncing along surface.

 

Soil Solutions

  • Crop rotation – rather than leaving fields bare after harvest, plant cover crops to maintain soil during winter.
  • Shelter belts – plant hedgerows or trees around fields to prevent wind erosion.
  • Contour ploughing – ploughing across slope rather than down to stop fast runoff.
  • Mulching – covering inactive field soil with layer of plant material.
  • Drainage systems – ditches catch run off which prevents over saturation of soil.

 

Major Soil Issues

  • Cause – pore spaces in soil filled with water. Occurs when precipitation higher than evapotranspiration or hard pans hinder proper drainage.
  • Problem – insufficient oxygen for plants to respire. Root tissue begins to decompose, stunting plant growth.
  • Strategies – avoid overwatering; drain soil with pipes or ditches; change soil composition such as adding sand to increase infiltration capacity.
  • Cause – build-up of salts in soil to toxic levels. Water flows form areas of low salinity to high. Occurs when high temperatures/rising water table draws water to surface and evaporate leaving behind salt deposits. Irrigation water can add excess salts.
  • Problems – high salinity means water flows away from roots, dehydrating plants. Toxicity may kill some fewer hardy varieties.
  • Strategies – manage rising water table; avoid intense irrigation.

 

Structural Deterioration

  • Cause – pore spaces in soil are lost due to heavy machinery or animals compressing soil and high salt content causes clay particles to clump together.
  • Problem – means plant roots can’t penetrate or respire in soil. Reduced capacity for water leads to dehydration. Land is harder to plough.
  • Strategies – cycle livestock; change soil structure (add sand to clay soils); manage salinization; maintain vegetation cover.
  • Food Security – ‘when all people at all times have access to sufficient, safe and nutritious food to maintain a healthy and active lifestyle’. Attaining security in a country depends on:
  • Food availability – produce and/or import enough food.
  • Food access – regularly obtain food by buying and/or by producing themselves.
  • Food quality and use – consume nutritious food prepared in a way that is hygienic and safe.
  • Australia is the most food secure country. 800 million go hungry each day.

 

Increasing Food Security

  • Agricultural expansion – more land can be converted to agricultural to increase production. CBA – it will damage ecosystems.
  • Intensive farming – producing as much food as possible from land available. Reduces clearing of land CBA – artificial chemicals in pesticides damage natural environment.
  • Provision of technology – Africa only produces 20% of its potential due to poor equipment and lack of fertiliser and seeds. Hydroponics can improve yields in arid climates CBA – it’s expensive so African countries can’t afford it.
  • GM crops – genetically modified crops can be more durable and produce higher yields. CBA -Not all countries have the means to do this. Questionable ethics. Reduces biodiversity.
  • Improve access to markets – transport links, lowered tariffs make it easier to export/import. CBA – cheap imports may undercut farmers trying to make a living.
  • Educating producers and consumers – about food waste, how to prevent loss by pests and disease. Educate distributors and consumers about increasing shelf life, using leftovers.
  • Local food systems – supporting local producers acts as a buffer against global food crises.

 

Health

  • Health – complete physical, mental and social well-being, not just absence of disease.
  • HALE – healthy life expectancy. Number of years a new born can expect to live in full health without major disease.
  • Morbidity – rate of disease in a population.
  • Prevalence rate – total number of cases in a population at a given time.
  • Incidence rate – number of new cases in a population during a given period.
  • Disability-adjusted life years (DALYs) – no. of healthy years of life lost to being in poor health.

 

Morbidity Patterns

  • Infectious diseases can be spread such as Malaria or HIV/AIDS.
  • Higher prevalence of infectious disease in LICs due to lack of sanitation, clean water, healthcare, limited education and overcrowded conditions.
  • Non-communicable diseases can’t be caught such as cancer, heart disease.
  • Higher prevalence of non-communicable disease in HICs due to higher life expectancy so more chance to develop diseases associated with old age, unhealthy diets of processed foods and lack of exercise.
  • Incidence rates for cancer are considerably higher in HICs compared to LICs however the % of cases resulting in death are considerably higher in LICs due to lack of availability to treatment.

 

Epidemiological Transition – Changing Mortality Patterns

  • Stage One (Age of Pestilence and Famine) – high death rate from infectious disease. Average life expectancy low such as Angola.
  • Stage Two (Age of Receding Pandemics) – deaths from infectious disease fall due to improved conditions. Average life expectancy begins to increase such as Haiti.
  • Stage Three (Age of Degenerative and Man-made Disease) – non-communicable disease replaces infectious as main cause of death. Life expectancy continues increasing such as Russia.
  • Stage Four (Delay of Degenerative disease?) – non-communicable disease prevented or onset delayed, and death rate reduced due to improved treatment. Life expectancy high such as UK.
  • Countries move through stages as they become more economically and socially developed:
  • Malnutrition decreases as food availability increases, so does ability to fight disease.
  • Clean water more widely available, sanitation improves reducing spread of disease.
  • Better access to healthcare to prevent disease.
  • Better health education to inform on how to avoid disease.