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Explain Natural Landscapes

Page history last edited by Mr G 8 years, 9 months ago

 

 

2.1 Explain Natural Landscapes.

 

In this topic we will be studying The Amazon rain Forest.

 

This exam has five main areas that the exam will focus on

 

  1. the characteristics of a large natural environment
  2. how the elements and processes of the large natural environment interact
  3. how a large natural environment is formed and changes over time
  4. how people interact with a large natural environment
  5. How perspectives have changed in terms of how we use this natural environment 

 

I will go through each area and provide websites and notes for each one.

 

1          the characteristics of a large natural environment

 

A tropical rainforest is an area of the planet that experiences a great deal of rain and sunshine due to its equatorial location.  Rainforests form along the Equator as this is where the planet is warmest and this warmth creates convection rainfall.  The combination of light, warmth and moisture means there is very fast and prolific vegetation growth in the area - http://www.bbc.co.uk/schools/gcsebitesize/geography/ecosystems/tropical_rainforests_rev2.shtml

 

The Amazon Rainforest is the largest rainforest on the planet taking up much of the northern half of South America. 

 

  

The Amazon rainforest, also known as Amazonia, is one of the world's greatest natural resources. Because its vegetation continuously recycles carbon dioxide into oxygen, it has been described as the "Lungs of our Planet". About 20% of earth's oxygen is produced by the Amazon rainforest.

The Amazon rainforest gets its name from the Amazon River, the life force of the rainforest. The Amazon River begins in the Peruvian Andes, and winds its way east over the northern half of South America. It meets the Atlantic Ocean at Belem, Brazil. The main river is about 4,080 miles long. Its drainage basin covers 2,722,000 million square miles, and lies in the countries of Brazil, Columbia, Peru, Venezuela, Ecuador, Bolivia, and the three Guyanas.

The Rainforest is not uniform in its nature and the most dense rainforest is found at low altitudes on the wide floodplains of the Amazon River.  As the land rises towards the Andes or in the Brazilian and Guyanan Highlands the vegetation changes.  This is a form of spatial variation.  The following diagram was taken from an exemplar exam answer about variation in natural landscapes and shows the different types of rainforest found in the region

 

 

 

2          how the elements and processes of the large natural environment interact

 

The elements of a landscape are the things we find in it.  Mountains, rivers, trees etc.  Processes are the natural systems that help to create and maintain those elements.  The Processes interact and this creates unique landscapes.  Here are some examples of processes that are occurring in the rainforest and how they interact

 

The Rainforest Water Cycle

 

The roots of plants take up water from the ground and the rain is intercepted as it falls - much of it at the canopy level. As the rainforest heats up, the water evaporates into the atmosphere and forms clouds to make the next day's rain. This is convectional rainfall.  Without convection rainfall the vegetation would not be able to grow in this area and it would not be a rainforest.  This is an example of a climatological process creating an element of the landscape.

 

The Rainforest nutrient cycle

The rainforest nutrient cycling is rapid. The hot, damp conditions on the forest floor allow for the rapid decomposition of dead plant material. This provides plentiful nutrients that are easily absorbed by plant roots. However, as these nutrients are in high demand from the rainforest's many fast-growing plants, they do not remain in the soil for long and stay close to the surface of the soil in the humus layer. If vegetation is removed, the soils quickly become infertile and vulnerable to erosion.  Without a humus layer and quick decomposition caused by the hot climate and animal life there would not be enough nutrients to support the massive amounts of plantlife in the Rainforest.  Beneath the humus layer the soil is red due to the presence of iron.  We call it a ferralitic soil.  This is an example of a biogeographical process creating an element of the landscape.

 

 

The Amazon is a Meandering River – River Meanders are a process.

 

Meandering rivers typically only contain one channel that winds its way across the floodplain.  Much of the Amazon Basin is an almost flat floodplain and the Amazon and its tributaries meander across it.  As the Amazon flows, it deposits sediment on banks that lie on the insides of curves (point bar deposits), and erode the banks on the outside of curves.  This means that meanders never stay the same.  The curves lengthen and stretch as erosion pushes them further across the floodplain.  The water will continue to find the quickest path downhill as it flows towards the Atlantic and when it finds a quicker path it will use it.  For example if one meander comes into contact with another the river can erode through and create a new strait channel effectively cutting out the need for the full curve of the meander.  The curve is left behind as an Oxbox Lake.  This is an example of  hydrological and pedological processes creating an element of the landscape.

 

 

 

The Amazon River Delta

 

 

The Amazon River is formed by tremendous amounts of rain falling on the mountains, hills and plains that it travels through.  As it moves over the land it erodes the land in ways described elsewhere in this document.  The sediment load created by that erosion is transported downstream and deposition takes place in a number of places.  On the Floodplain during a flood, on the inside of a meander and when the river reaches the sea.  When the river reaches the Atlantic the strong currents of the river are disturbed and changed by the tidal flow and waves of the Atlantic ocean.  The result is a general slowing of the river which means it loses its energy and deposits its sediment in large amounts.  Over time this sediment deposition has grown into islands some of which are as large as small countries in their own right.  For example the island of Marajo is roughly the same land area as Switzerland.  This is an example of a Hydrological and Pedological process creating new land.

 

3.  how a large natural environment is formed and changes over time

 

The following information is taken from an exemplar paper and is an exam style answer to a question about how the landscape was formed

 

(a) Land-building process Plate tectonics / Folding in the Amazon Basin

The Earth’s crust is constantly destroying and re-creating itself. The mechanism causing this is plate tectonics. The

Earth’s crust is made up of a series of plates that are constantly on the move at different rates, ranging from a few

centimetres every year to metres in some places. Convection currents of magma originating in the Earth’s mantle push the plates apart or together. The Amazon Basin was formed as a result of these plate movements.

The Amazon basin has been formed over the last 250 million years as Gondwanaland, the great southern continent,

began to split up. The South American continent moved away from Africa as the mid-Atlantic ridge widened. As it

moved westward, it collided with the Pacific and Nazca plates, resulting in the formation of the Andes Mountains by

folding. The uplift that created the Andes is still occurring and because of the height of the Andes, erosion processes

are very active there. Material from the mountains has been deposited in the basin in between the Andes to the west

and the ancient Brazilian Shield or Plateau to the east.

 

 (b) Land-modifying process – Transportation / Deposition by rivers in the Amazon Basin

The white water tributaries of the Amazon River all have their origin in the Andes Mountains. They carry large amounts

of sediments because the Andes is still rising rapidly and being eroded by ice and running water. Every year in the

rainy season, the rivers carry huge amounts of alluvial material from the Andes when floods occur. The rivers can rise 16–20 metres above their usual levels. When the rivers hit the flood plain, their speed is reduced and they are not able to transport the sediments. The material they transport is deposited on the flood plain. In Brazil, the flood plain is known as the varzea. Every year the varzea can gain up to 8 tonnes of sediment in this way. Some of the white water tributaries are the Rio Madeira and the Jura.  Rivers that flow from the ancient shield carry tiny amounts of sediment because the shield is no longer rising or being eroded much. Flooding is much less common but does lead to some material being deposited in the Amazon basin.  The rivers are called clear water tributaries, and examples are the Xinju and Tapajos.

 

In conclusion the flat Brazilian Plains that the Amazon flows over for most of its journey to the sea have been created by the Amazon river itself and by the action of processes such as Plate Tectonics.  Without the Andes Mountains there would be no plains however, the Amazon river and its tributaries had to erode those mountains, transport the sediment and deposit that sediment as a flat plain over millions of years before the Plain developed enough to become the rainforested Brazilian Plateau.

This is an example of geomorphological and pedological processes creating an element of the landscape.

 

4.  how people interact with a large natural environment

 

Over the course of our studies on this topic we have looked at a number of different groups of people and their involvement in the Amazon region we looked at.

 

  • ·         Cocaine Farming in Peru
  • ·         Cattle Ranching in Brazil
  • ·         Oil Drilling in Ecuador
  • ·         Mining and Forestry in Brazil and Peru

 

In particular we watched Ross Kemp’s Amazon which can be found online here:

https://www.youtube.com/playlist?list=PLptMQlY6j0-GD2MoDUuXaSgGHCzzVP8QT

https://www.youtube.com/watch?v=KgJCahR_Mak

https://www.youtube.com/watch?v=rKu82uJzC9E

 

and Top Gear Bolivia can be found here

 

Part 1 http://www.dailymotion.com/video/x182yp2_top-gear-uk-bolivia-chile-14x06-sub-pt-br-part-1_auto

Part 2 http://www.dailymotion.com/video/x183q6i_top-gear-uk-bolivia-chile-14x06-sub-pt-br-part2_auto?from_related=related.page.int.behavior-meta2.fea06523eb9c1f57c11fa86c9b99ac13143587797 

 

We also talked about:

 

  • ·         The Trans Amazonian Highway
  • ·         The Jari Project  
  • ·         The Carajas Project

 

The Trans Amazonian Highway

 

The Trans-Amazonian highway was one of the most ambitious resettlement-economic development programs ever devised, and one of the greatest failures. In the 1970s, Brazil planned a 2000-mile highway that would bisect the massive Amazon forest, opening rainforest lands to settlement by peasants from the crowded, drought-plagued north and development of its timber and mineral resources to maintain the country's impressive economic growth.

Colonists would be given a 250-acre lot, six months' salary, and easy access to agricultural loans, in exchange for settling along the highway and converting the surrounding rainforest into agricultural land. The plan would grow to cost Brazil US$65,000 (1980 dollars) to settle each family, a staggering amount for Brazil, a developing country at the time.

The project was plagued from the start. The sediments of the Amazon Basin rendered the highway unstable and subject to inundation during heavy rains, blocking traffic and leaving crops to rot. Harvest yields for peasants were dismal since the forest soils were quickly exhausted, and new forest had to be cleared annually. Logging was difficult due to the widespread distribution of commercially valuable trees. Rampant erosion, up to 40 tons of soil per acre (100 tons/ha) occurred after clearing. Many colonists, unfamiliar with banking and lured by easy credit, went deep into debt.

Adding to the economic and social failures of the project, are the long term environmental costs. After the construction of the Trans-Amazonian highway, Brazilian deforestation accelerated to levels never before seen and vast swaths of forest were cleared for subsistence farmers and cattle-ranching schemes. The Trans-Amazonian highway is a prime example of the environmental havoc that is caused by road construction in the rainforest.

 

The Jari Project

 

In 1967 Daniel Ludwig bought 16,000 squake kilometres of Brazilian rainforest with the intention of growing Pine trees to make paoer with.  He set up a papermill in the region and began cutting down the original vegetation and planting Pine and also running cattle on the remaining cleared land.

 

The scheme failed economically because of the so called “Amazon Factor”  The soils were not good enough to support the growth of pine and when he cleared the land to plant he also removed much of the humus layer where the nutrients were found.  The distance from the project to markets was too great and perhaps most costly of all the insects of the region gave his workers malaria and ate his paper stock.

 

The Carajas project

 

This is a $62 billion complex of mines, roads, towns, power stations and dams that was began in the 1980’s  The project continues today and it is estimated that by the time it is completed over 90 million hectares of forest will have ben removed

 

5 facts about the Carajas Project

1. In 2007, 296 million metric tons of iron ore were dug out of the mine, which is estimated to contain a total of 18 billion tons of iron ore, gold, manganese, copper, and nickel
2. Most of the ore is taken 690km from the mine to the port of Sao Luis on the Atlantic coast by rail
3. To the north-west of Carajas, on the south bank of the River Amazon, is the large bauxite mine, (used for making aluminum) at Trombetas
4. Mining and refining these valuable metals need large amounts of electricity which has therefore been provided by the Tucurui Hydro Electric station.
5. Building the railway to Sao Luis caused disputes amongst the natives living there

Read more: http://wiki.answers.com/Q/What_is_the_carajas_project#ixzz25doH8AUv

 

5.  How peoples perceptions of a large natural environment change over time

 

We have looked in some detail at how perceptions and uses of the forest have changed over time from the early Amerindians to today’s multi national farming and forestry corporations and the clandestine mining and drug manufacture operations.  Much of the modern uses of the forest have been covered above but in this section of these notes I want to mention the more traditional uses of the rainforest by the native Amerindian tribes.

 

Shifting Cultivation

The shifting agricultural system is an ecosystem modified by man's activities at a relatively low level in comparison with other forms of agricultural activities.  The chief cultural practices include the following:

Making a Clearing.  The tribe first selects a small patch of rainforest.  To create a clearing on the forest, the tribe selectively slashes the natural vegetation by simple tools and burns the logs,  so the nutrients are released as ash which dissolves and is washed by rain into the soil as natural fertilizers.

Growing Crops.   A variety of food crops are grown on the land such as rice, maize, cassava . The crops grow very quickly, some are ready to harvest after four to six months. After 2 or 3 years, due to decline in soil fertility, the yield of successive crops declines and weeds grows extensively.

 

Abandoning the Clearing.  The site is abandoned and cultivation moves to another site, where another patch of the rainforest will be cleared for a new swidden. They will try not to return to the former clearings for at least 50 years.

Other Features include:

  1. short crop period is lowed by long fallow
  2. long growing season and continuous growth
  3. mainly food crops are grown for subsistence
  4. small scale
  5. small fields

Yanomami and Kayapo Indians of the Amazon practises this type of farming.

Land Rotation

     In the traditional practice, the follow period between croppings of the same patch of land is at least 20 years or longer. The soil of the tropical rainforest is inherently infertile. Most of the nutrients are kept in the bulk biomass of trees. A long period of abandonment allows the rainforest to regenerate and the fertility of the land to be restored. The nutrient content of both vegetation and soils is replenished. Regeneration protects the soil from erosion and controls of the spread of weeds and pests.

This website gives more information on human uses of the rainforest

 

http://www.bbc.co.uk/schools/gcsebitesize/geography/ecosystems/human_uses_rainforest_rev1.shtml

 

 

The Brazilian Government’s Perspective

 

This is an excellent case study to use when we look at the changing perspectives of a group with regard to the Amazon Rainforest.

 

In the 1950’s Brazil was a poorer nation with a GDP per capita of US$22.  By contrast the average GDP per capita for the whole world was around $450.    Today Brazil’s GDP per capita is US$11208 whereas the average world GDP per capita is US$10512.  A large part of the economic growth of this nation has been to use its natural resources to its own advantage.

 

In the 1960’s, 70’s and 80’s Brazil’s government grated permissions to a number of major developments that would have huge impacts on the natural landscape of the Amazon Rainforest.  The Jari project (1967), The trans Amazonian Highway (1972) andThe Carajas Project (1980) are excellent examples of how the economics of Brazil was a major factor in the perspective of the government at the time.  All of these had adverse effects on the Rainforest.  These case studies are mentioned above.

 

Today things are very different.  In 1998 Brazil signed the Kyoto protocol (http://unfccc.int/kyoto_protocol/items/2830.php) which aims at reducing carbon emissions.  Deforestation is a key contributor to carbon emissions.  In Brazil over the past nine years, the rate of deforestation has dropped by 70 percent.  Brazil’s reduction in emissions from deforestation is the largest contribution so far by any country—rich or poor—to reducing global warming pollution. The factors responsible for this accomplishment include government policies and enforcement actions by prosecutors, on both the federal and state levels; incentives created by Norway’s pledge of up to $1 billion in results-based compensation; the concerted pressure exerted by non-government organizations (NGOs) on the government and the soy and beef industries; and the positive response by those industries, resulting in the 2006 soy and 2009 beef moratoria (http://news.mongabay.com/2009/1007-greenpeace_cattle.html). Political leaders, such as President Luis Inácio Lula da Silva, Minister of the Environment/2010 Green Party presidential candidate Marina Silva, the independent public prosecutors, and several state governors can also claim an important share of the credit. 

 

This is the document we used in class - http://thesolutionsjournal.org/node/237165 

 

These notes should be supported by the work we did in class and also the information contained in the text book we have been using ‘Natural landscapes by J. Mark Hensman pages 40-85

 

 

 

 

 

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