Posts Tagged ‘terrestrial’

  • List the significant abiotic (physical) factors of an ecosystem.

Ecosystems can be divided into 3 types:

  • Marine: the sea, salt marshes mangroves are all characterized by the salt content.
  • Freshwater: rivers, lakes and wetlands.
  • Terrestrial: land-based.

Each ecosystem has its on abiotic factors:

Marine:

  • salinity
  • pH
  • temperature
  • dissolved oxygen
  • wave action

Freshwater:

  • turbidity
  • flow velocity
  • pH
  • temperature
  • dissolved oxygen

Terrestrial:

  • temperature
  • light intensity
  • particle size
  • slope/aspect
  • soil moisture
  • drainage
  • mineral content
  • Describe  and evaluate methods  for measuring at least three abiotic (physical) factors within an ecosystem.

Abiotic factors that can be measured within an ecosystem include the following:

Marine:

  • salinity: this can be measured  using electrical conductivity ( with a datalogger) or by the density of the water (water with high salt content is more denser than low-salt water).
  • pH: this can be measured using a pH meter, or datalogging pH probe. Indicator solution may also be used.
  • temperature: ordinary thermometers are too fragile to use for fieldwork, and are hard to read. An electric thermometer allows temperature to be measured  in depth.
  • dissolved oxygen: a meter with oxygen-sensitive electrodes connected that measures dissolved oxygen. One should be careful as doing things wrong may contaminate the air.
  • wave action: this is measured by using a dynomometer which measures the force in waves.

Freshwater:

  • turbidity: can be measured using a Secchi disc, nephlometer or turbidimeter.
  • flow velocity: can be measured by timing how long it takes a floating object to travel a certain distance or by using a flow-meter.
  • temperature: ordinary thermometers are too fragile to use for fieldwork, and are hard to read. An electric thermometer allows temperature to be measured  in depth.
  • dissolved oxygen: a meter with oxygen-sensitive electrodes connected that measures dissolved oxygen. One should be careful as doing things wrong may contaminate the air.

Terrestrial:

  • temperature: ordinary thermometers are too fragile to use for fieldwork, and are hard to read. An electric thermometer allows temperature to be measured  in depth.
  • light intensity: is measured using a light-meter.
  • wind speed: a Beufort-scale is used to measure wind speed and precise measurements can be made with a digital anemometer.
  • particle size: this determines the drainage and water-holding capacity and is measured by using a series of sieves.
  • slope: this is measured using a clinometer and using a compass.
  • soil moisture: by weighing the samples then heating them it shows the amount of water that has evaporated and the moisture levels.
  • mineral content: the loss on the ignition test can determine mineral content. The samples are heated for several hours to let volatile substances to escape.
Abiotic data can be collected using instruments that avoid issues of objectivity as they directly measure quantitative data. Instruments allow us to record data that would otherwise be beyond the limit of our perception.
  • 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.

Inputs:

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

Outputs:

  • 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.

Input:

  • 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)

Outputs:

  • 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.

Agribusiness

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.