Posts Tagged ‘environment’

  • Explain difficulties in applying the concept of carrying capacity to local human populations.

If one were to examine the needs of a given species and the resources available, it could be possible to estimate the carrying capacity of that environment for the species. This is problematic when it comes to the human population for many reasons like:

  • Resources used by humans are much more than any other species and when this source becomes limited humans begin to substitute one resource for another. The use of resources change from person to person, lifestyle to lifestyle, time to time and population to population.
  • Developments in technology increase the changes of the resource consumption.
  • The human population also import resources very often which come from outside their environment, which makes the grow beyond the boundaries set by their local resources and lets their carrying capacity increase. This however does not affect the global carrying capacity.

These variables make it almost impossible to make reliable estimates of carrying capacities for the human populations.

*Carrying capacity: The maximum number of a species or ”load” that can be sustainably supported by a given environment.

Here we can see 3 models of a population growing and approaching carrying capacity.

*Optimum population: the number of people which when working with all the available resources, will make the highest per capita economic return. it shows the point at which the population has the highest standard of living and quality of life.

Standard of living is the result of the interaction between physical and human resources and can be expressed as:

Standard of living: (natural resources X technology) / population

*Over-population: this happens when there are too many people compared to the resources and technology available for the standard of living. They suffer from natural disasters such as droughts and famine, low incomes, poverty, poor living conditions and a lot of emigration.

*Under-population: this happens when there are too many resources in one area that is too much for the people living there. Countries like this could export their surplus food, energy and mineral resources.

  • Explain how absolute reductions in energy and material use, reuse and recycling can affect human carrying capacity.

Human carrying capacity is determined by the rate of energy and material consumption, the level of pollution and the extent of human interference in global life-support systems. While reuse and recycling reduce these impacts, they can also increase the human carrying capacity.

*Recycle: when a household or industrial waste is reused and made into another product, like plastic, metals and paper.

*Re-use: when a product is used more than once by returning it to the manufacturer or processor each time. This is very energy efficient and more efficient than recycling.

*Reduce: this is when energy use is decrease for example turning off the lights when not needed or using the amount of water needed in a kettle.

*Substitution: when using one resource over the other, the use of renewable source over a non-renewable source is a major benefit to the environment.


  • Outline the issues involved in the imbalance in global food supply.

There is enough food on the world to feed us all, however there is an imbalance in the food supply globally. Many people from the LEDCs are suffering from not getting enough energy, proteins and minerals. Around 3/4 of the world’s population is not eating enough and an average of 1 million are going hungry, the majority of these people lives in the LEDCs. It is estimated that every 6 seconds a child dies of hunger.

The price of food plays a major role here, if prices were to just increase by 10% it could lead to an increase of 40 million people in food poverty. However even though there is such a huge group of people in need of food there is a surplus of food in the MEDCs with markets producing to much food for the population.

This has lead to people in the MEDCs to consumer more food then they need as the MEDCs increased wealth has allowed them to buy more. There are import tariffs imposed by the MEDCs to make the import of food more expensive, which can ruin the exporting countries.

In the LEDCs they make money for the country through food production, from crops such as sugar cane and tobacco. So they need this production for making money but when the MEDCs increase import tariffs the LEDCs are in trouble.

MEDCs want to make money from products in the country and not let the imported goods become the cheaper choice. Despite all this prices of food in the MEDCs is fairly expensive as seasonal foods have disappeared as imports fill gaps. The struggle in the LEDCs to make money has caused prices to rise, this makes it difficult for the population to afford local productions.

Climate changes have also affected the LEDCs as droughts for example reduce the amount of growing land. Global warming could lead to countries suffering from high temperatures which could destroy crops.

As more land is used for settlement and industry, there is an increase in intensifying production on existing farm land. MEDCs food production is complex as it involves high levels of technology, low labour and high fuel costs. MEDCs have become more technocentric.

Agriculture in the LEDCs are in contrast and have low levels of technology, lack of capital and high levels of labour.

  • Compare and contrast the efficiency of terrestrial and aquatic food production systems.

*Second law of thermodynamics: states that energy goes from a concentrated form (like the sun) to a dispersed form (like heat), the  availability of energy to do work therefore diminishes on the system becomes increasingly disorder. It explains how energy transformations in living systems can lead to loss of energy from the system. The order in living systems is only maintained by constant input of new energy from the sun.

We get to see from the second law of thermodynamics that energy conversion through food chains is inefficient and that energy is lost by respiration and waste production at each level within the food web.

Energy in sunlight -> producer (90% energy lost) -> primary consumer (9% energy lost) -> secondary consumer (0.9% energy lost)

100% -> 10% -> 1% -> 0.1%

Terrestrial systems:

Most food is harvested from low trophic levels (producers and herbivores). Systems that produce crops are more energy efficient then those which produce livestock. This is because energy is greater in proportion in the low trophic levels. Even though it is efficient to use arable systems, many cultures still use livestock as part of their farming system. Taste and cultural demand play a major role in this and the animals also provide a source protein which is essential for the human diet. Animals are also used as working animals in some cultures.

Terrestrial farming systems are divided into several types:

  • Commercial farming: is farming for profit, often of a single crop
  • Subsistence farmer: produces only enough yo geed their family with non to sell for profit

Both commercial and subsistence can be intensive or extensive farms.

  • Intensive farms: take a small area of land but aim for a high input
  • Extensive farms: are large in comparison to the money and labour put into it

The efficiency of the system can be calculated by comparing outputs to inputs per unit area of land.

Aquatic systems:

Due to human taste, most food harvested is from the higher trophic levels where the total storage is much smaller. There is less energy then crop production, although energy conversion is aquatic systems are more efficient then terrestrial chains, the system receives less sunlight then terrestrial chains.

  • Compare and contrast the inputs and outputs of materials and energy (energy efficient), the system characteristics, and evaluate the relative environmental impacts for two named food production systems.

Terrestrial Systems:

Intensive Charolais beef production in France:

In Western Europe the Charolais beef is one of the beef brands chosen. Through selective breeding and genetic engineering bloodlines that puts weight on exist but has a low fat cover. Charolais lives under controlled conditions, they are fed with high proteins and treated with antibiotics to make sure they are healthy. Lots of energy is used in transporting and processing the finished meat.

Cattle raised outdoors however grown on single monoculture ( cultivation of a single crop on a farm or in a region or country) grass land in large fields with a high stock rate. To keep the productivity of these fields going, large amounts of fertilizer are used.

This intensified farming e the 1940’s with the aim of producing cheaper meat has led to habitat loss as they have been removed to make bigger fields and cases of Eutrophication have increased as excess use of fertilizers and large amounts of slurry produced in the system enter water courses. Fear of causing antibiotic resistance in human bacteria through bioaccumulation.


  • energy for food distribution
  • food supplements
  • selective breeding and genetic engineering (system characteristics)
  • indoor rearing
  • fertilizers to maximize grass production
  • antibiotics and hormones


  • cheap meat (socio-cultural)
  • habitat destruction to make bigger fields (environmental impact)
  • antibiotic resistance
  • Eutrophication

Nomadic cattle grazing of the Himba:

The Charolais beef production can be contrasted with the Nomadic cattle grazing of the Himba. The Himba people are from North West Namibia, they survive by being Nomadic hunters/grazers. They also have a tight bond with the cattle they graze. During the dry seasons the Himba move their cattle from area to area until the grass is used up until the raining season, they go to better pastures. Cattle to the Himba are very important as they provide; meat, milk, skins and even dung for fires. Prestige between the Himba is seen by how many cattle they have, not the size of the cattle. The cattle during the dry season may start competing with herbivores. This has increased especially with global warming drought periods. This can lead to soil erosion as extra grazing pressure removes the grasses that hold the top soil together.


  • nomadic grazing moving from place to place so land has a chance to recover
  • cattle survive on low grade natural forage with no supplements
  • during drought cattle die as grass disappears adding patches of nutrients to the soil (environmental impact)


  • Himba cattle provide meat, milk and fuel (dung)
  • owning cattle gives status in community (socio-cultural)
  • during drought times Himba cattle compete with wild grazers for food this can lead to soil erosion as well as food shortage (environmental impact)
  • Discuss the links that exist between social systems and food production systems.

There are many links between social systems and food production system. Examples given are shifting cultivation, wet rice agriculture (South-East Asia) and agrilbusiness

Shifting cultivation

Shifting cultivation supports small communities and sometimes individual families. It is also known as ”slash and burn” agriculture, as new land is cleared by cutting down small areas of forest and setting fire to them. Ash fertilizers the soil for a while and the clearing produced enables crops to grow. When the land can’t be used any more, the farmer goes to a new land area. Once the land has recovered, farmers go back to the land.

This is performed in many tropical forest areas, such as the Amazon regions. This is possible as there is low population density. If population densities increase too much, old land is returned too before fertility has been restored, this encourages shifting cultivation. There are people who have close connection with nature, like shifting cultivators in the Brazilian Amazon. They show a closer connection between social systems and ecological systems than the societies living away from natural systems, such as city dwellers. Urban capitalists in Brazil are more likely to view the interior of a country as a new frontier, and the rainforest as a resource for development and cash (technocentric approach). The lack of understanding of the nature makes them underestimate the true value of natural resources. They may also make decisions which produce wasteful and damaging actions.

Wet rice ecosystem of South-East Asia

Padi field agriculture has become the dominant form of growing rice in South- East Asia. It is intensive subsistence farming, using high labour but low technology. As there is a high population, a lot of food is needed. Especially rice as it is part of the Asian diet as well as their culture. Padi fields are placed by rivers and areas that flood naturally, so that the fields get new deposits of silt and increased fertility. They should be placed in heavy clay soils, as sand and light textured soils are not suitable as water drains away. Warm weather and high rainfall help productivity all year round.


Supply most of the products found in supermarkets. Many have travelled long distances from around the world. Its a non-seasonal climate food supply throughout the year, so once-seasonal crops are available year-round in MEDCs.

The aim of agribusiness is to maximize productivity and profit to compete with the global market. This is large scale monoculture, intensive use of fertilizers and pesticides, mechanized ploughing and harvesting, and food production geared to mass markets including export.

This type of agriculture has a huge impact on the environment, with loss of biodiversity, and increased run-off pollution. National political economies encourage agribusiness as it supports the national income, this had lead to many people living off farming to move into the towns and cities to get new work.

  • Outline how soil systems integrate aspects of living systems.

Soil forms the Earth’s atmosphere, lithosphere (rocks), biosphere (living matter) and hydrosphere (water). Soil is what forms the outermost layer of the Earth’s surface.

Soils are important to humans in many ways:

  • soil is the medium for plant growth, which most of foods for humans are grown in
  • soil stores freshwater, 0.005% of world’s freshwater
  • soil filters materials added to the soil, keeping quality water
  • recycling of nutrients takes place in the soil when dead organic matter is broken down
  • soil is the habitat for billions of micro-organisms, as well as other larger animals
  • soil provides raw material in the forms of peat, clay, sands, gravel and minerals

Soil has matter in all three states:

  • organic and inorganic matter form the solid state
  • soil water form the liquid state
  • soil atmosphere forms the gaseous state

* Soils are an important source for humans and take time to develop and therefore be counted as a non-renewable resource.

The Soil System

O – Organic Horizon:

  • l – undecomposed litter
  • f – party decomposed litter
  • h – well decomposed humus

A – Mixed mineral-organic Horizon:

  • h – humus
  • p – ploughed in field or garden
  • g – gleyed or waterlogged

E – Eluvial or leached Horizon:

  • a – strongly leached, and ash coloured
  • b – weakly bleached, light brown

B – Illuvial or deposited

  • Fe – iron deposited
  • t – clay deposited
  • h – humus deposited

C – Bedrock or parent material

  • r – rock
  • u – unconsolidated loose deposits

Transfers of materials (including deposition) results in reorganization of the soil. There are inputs of organic and parent material precipitation, infiltration and energy-outputs include leaching, uptake by plants and mass movement. Transformations include decomposition, weathering and nutrient cycling.

  • Compare and contrast the structure and properties of sand, clay and loam soils, including their effect on primary productivity.

Soil structure depends on:

  • Soil texture ( the amount of sand and clay )
  • dead organic matter
  • earthworm activity

For optimum struction, variety of pure sizes are required to allow root prevention, free drainage and water storage. Pore spaces over 0.1 mm allow roots growth, oxygen diffusion and water movement where as pore spaces below 0.5 mm help store water.


  • fertile in temperate locations
  • in tropical areas clay is permeable and easily penetrated by roots
  • nutrient deficient / easily  leached in tropics

The more clay present in soil the higher the force needed to pull a plough.

Different soil types have different levels of primary productivity:

  • sandy soil – low
  • clay soil – quite low
  • loam soil – high

Primary productivity of soil depends on:

  • mineral content
  • drainage
  • water-holding capacity
  • airspaces
  • biota
  • potential to hold organic materials

*Shrinking limit: state which the soil passes from having a moist to a dry appearance.

*Plastic limit: occurs when each ped is surrounded by a film of water sufficient to act as a lunricant.

*Liquid limit: occurs when there is sufficient water to reduce cohesion between the peds.

*Field capacity: maximum amount of water  that a particular soil can hold.

  • Outline the processes and consequences of soil degradation.

*Soil degradation: the decline in quantity and quality of soil. It is also erosion by wind and water, biological degradation (loss of humus and plant or animal life), physical degradation (loss of structure, changes in permeability), chemical degradation (acidification, declining fertility, changes in pH, salinity).

Causes of degradation:

  • Overgrazing: reduces the vegetation cover and allows the surface to be vulnerable to erosion. Dry regions are vulnerable to wind erosion.
  • Deforestation: removed of woodland cause roots in the soil to die and exposure to erosion if on slopes.
  • Cultivation: exposure of the bare soil before/after planting can cause large amounts of run-offs and create rills and gullies. Irrigation in hot areas can cause salinization.
  • Climate change: the higher the  temperature and changing precipitation patterns can lead to direct impacts on soil. Higher temperatures cause higher decomposition of organic matter. More precipitation and flooding cause more water erosion and droughts cause more wind erosion.

Many forms and causes of degradations:

  • Water erosion ( 60% of soil degradation)
  • Wind erosion
  • Acidification (toxification), when the chemical composition of the soil is changed.
  • Eutrophication (nutrient enrichment).
  • Desertification can be caused in extreme cases.
  • Climate can intensify the problem and effect of hydrology.

This shows that the soil degradation’s damage is world spread and has occurred on 15% of the world’s total area.

  • Outline soil conservation measures.

Strategies for combating soil degradation is not so common or widespread and to reduce this risk farmers are encouraged and informed about the processes and conservation methods. Farmers are in the need of beginning with extensive management practices like organic farming, afforestation, pasture extension, and benign (gracious) crop production. However to make this work there is a need of policies.

There are a few methods to reduce or prevent erosion, which can be mechanical or vegetation cover and soil husbandry.

Mechanical methods: are used to reduce water flow including bunding, terracing, and contour ploughing. The goal is to prevent and slow down the movement of rain water down the slopes.

Cropping and husbandry methods:

This method is used against water and wind damage.

It focuses on:

  • keeping the crops safe as long as possible
  • keeping the ground and place of the crop stable after harvesting
  • planting a grass crop

Grass crop keeps the action of the roots in binding the soil and also it decreases the action of wind and rain on the soil surface. with increased organic content it allows the soil to hold more water and reduce the mass, movement and erosion and stabilizing the soil structure.

To prevent damage to the soil structure, care should be taken to reduce the use of heavy machinery is necessary especially on wet soils and ploughing on soils that are sensitive to erosion.

Management of salt-affected soils:

The three main ways of managing salt-affected soils is by:

  • flushing the soil with water and leaching the salt away
  • putting chemicals to replace sodium ions on the clay and colloids with calcium ions for example by using gypsum a calcium sulphate
  • reduction in evaporation losses to reduce the upward movement of water in the soil

Summary of the conservations methods:

Both socio-economic and ecological factors have been ignored and integrated approach to soil conservation is needed, non-technological factors like population pressure, social structures, economy and ecological factors can determine the appropriate technical solutions. There are a variety of methods to use like  strip and ally cropping, rotation farming, contour planing, agroforestry, adjusted stocking levels mulching, use of cover crops, construction of mechanical barriers such as terraces, banks and ditches.

  • Explain the concept of resources in terms of natural income.

Ecologically minded economists describe resources as ”natural capital”. If properly managed, renewable and replenishable resources are forms of wealth that can produce ”natural income” indefinitely in the form of valuable goods and services.

This income may consist of marketable commodities such as timber and grain (goods) or may be in the form of ecological services such as the flood and erosion protection provided by forests (services). Similarly, non-renewable resources can be considered in parallel to those forms of economic capital that cannot generate wealth without liquidation of the estate.

*Natural capital + natural income: raw materials from the environment (natural capital), are harvested and used by producers to generate products and services (natural income) that are then used by consumers.

  • Define the terms renewable, replenishable and non-renewable natural capital.

*Renewable resource: is a natural resource that the environment continues to supply or replace as it is used, and whose emissions and wastes are recycled in a sustainable way. They can be used over and over again. Renewable natural capital, such as living species and ecosystems, are self-producing and self-maintaining and uses solar energy ad photosynthesis. This natural capital can yield marketable goods such as essential services when left in place, for example, climate regulation.

*Replenishable resource: non-living resources which are continuously restored by natural processes, (ex. rivers, ozone layer) as as they are used up. They provide sustainable natural income as the natural capital is not diminished. They depend on abiotic processes for their replenishment. (in contrast to renewable resources which depend on biotic processes)

*Non-renewable resource: natural resources which cannot be replenished within a time scale of the same order as that of which they are take from the environment (cannot be replenished at the same they are used). Any use of these resources results in depletion of the stock. These include: fossil fuels, and minerals.

Renewable: solar energy, biomass energy, wind energy, hydro-power energy and geothermal energy.

Non-renewable: fossil fuel oils, coal, nuclear and natural gas.

  • Explain the dynamic nature of the concept of a resource.

Cultural, economic, technological and other factors influence the status of a resource over time and space. For example, uranium, due to the recently become a valuable resource. What this all means is that resources are dynamic, its status may change, it might become valuable.

  • Explain the concept of sustainability in terms of natural capital  and natural income.

* Sustainability: means living, within the means of nature, on the ”interest” or sustainable income generated by nature capital. So using the global resources at the rate that allows natural regeneration and minimizes damage to the environment.

This can be encouraged by:

– ecological land-use to maintain habitat quality and connectivity for all species.

– sustainable material cycles, (ex carbon, nitrogen, and water cycles).

– social systems that contribute to a culture of  sufficiency that eases the consumption pressures on natural capital.

  • Discuss the concept of sustainable development.

* Sustainable development: development that meets current needs without compromising the ability of future generations to meet their own needs. Focuses on the quality if environmental, economic, and social and cultural development. The concept encompasses ideas and values that inspire individuals and organizations to become better stewards of the environment and promote positive economic growth and social objectives.

  • Calculate and explain sustainable yield from given data.

sustainable yield may be calculated as the rate of increase in natural capital, that is, that which can be exploited without depleting the original stock or its potential for replenishment. For example; the annual sustainable yield for a given crop may be estimated simply as the annual gain in biomass or energy through the growth and recruitment.

”development which meets the needs of the present without compromising the ability if the future generations to meet their own needs.”

SY= (annual growth and recruitment) – ( annual death and emigration)