Sunday, May 8, 2011

Biomes - Leaving Cert Geography Notes/Sample Answers


Biomes
You must attempt FOUR questions, as follows:
• Two questions from Section 1
• One question from Section 2
• One question from Section 3
THESE QUESTIONS ARE TO BE ANSWERED IN THE ANSWER BOOK.
SECTION 3 - OPTIONS
N.B. It is better to treat three or four aspects of the theme in some detail than to give a superficial treatment of a large number of points.
These questions require an essay style answer.
·       Introduce your answer.
·       Take 3 or 4 points and develop them in turn.
·       Summarise and conclude.
There are 80 marks for this question; 20 m for cohesion and 60 m for the 3 or 4 points developed 
(3 x 20 m or 4 x 15 m).

The pattern of world climates has given rise to distinctive biomes. These biomes are world regions characterised by groups of plants and animals adapted to specific conditions of climate, soils and biotic interrelationships. Biomes have been altered over time by human activities such as forest clearance by early settlers; intensive agricultural practices and the relatively recent felling of tropical rain forests.
Students should identify one biome for study. They should examine this biome in terms of climatic and soil characteristics and related patterns of animal and vegetation distribution. It would be best to choose a biome that corresponds to one of the regions chosen for study in Core Unit 2 - Regional Geography. The Cool Temperate (or Temperate Forest) biome would suit the Regional choice of Ireland or Western Europe or parts of the U.S.A. If you have chosen North America for your continental region then the Desert biome of e.g. California would be suitable. India provides a good example of the Tropical biome.

In the case of a description of any biome you should give the:
  • Location - The western side of continents between 40º and 60° North and South of the equator. Includes Ireland, parts of U.S.A. Canada, Australia, New Zealand.
  • Climate - As the name implies it is cool, temperate (no-extremes) and moist. Lots of rainfall; mainly southwesterly winds and temperature range from about 4°-18°C.
  • Vegetation - Natural vegetation is temperate deciduous forest A lot of this has been cleared for agriculture.
  • Soils - Soils vary but fertile brown earth predominate.
  • Fauna - A well developed food chain of herbivores (rabbits, deer) and carnivores (foxes etc.).
  • Human Interference - Most of the natural vegetation has been removed for agricultural or forest purposes. Many of these areas have a long history of settlement. In Ireland, for example, almost all of the natural deciduous forests have been removed. In recent years, some of this land has been replanted with conifers.

Answer

An ecosystem is a community of animals and plants treated as a unit with its physical environment, which includes the soil and climatic types present. Typically the characteristics are unique and relatively uniform. On a global scale ecosystems of one type are referred to as a biome.  The biome that I have studied is a Desert Biome. The general climatic and soil characteristics have been adapted to by plants and animals alike. These general characteristics can be looked at individually.
Climatic Characteristics
The weather here is usually very stable in that there are clear skies and little rainfall. Typically < 100 mm of rain a year = desert. The diurnal range is very high. Daytime temperatures can reach 50° and night temperatures can go down to 0°.  The rain shadow effect produced by high mountains can create deserts, for example, theGobi desert north of the Himalayas.  Here the absence of rainfall creates the arid environment that prevails in this climate type. Deserts are also influenced by cold coastal currents, which are moving to the equator from higher latitudes.  These occur on the western fringes of continents, e.g. Kalihari.  Winds that blow over these currents are cooled, decreasing their capacity to hold moisture.  When the air contacts hotter land the air heats and can retain moisture thus the coastal region remains desert. They are generally found between 15° and 30° south and north of the equator, e.g. Sahara. Deserts tend to lie on the western margins or in the centre of continents. There are also some deserts in mid-latitudes between 30° and 40° north and south of the equator.  These are found within the continental interiors, e.g. Gobi.  Deserts can be very arid, arid and semi-arid.  This can depend on a number of factors including: high-pressure belts, rain shadows, cold ocean currents and continentality.
As most deserts are located where high-pressure belts exist (15° to 30° north and south of the equator) air is heated and rises at the equator, moves northward and southward until the air contracts, becomes denser and falls to earth at about 30° latitude.  Compression warms the descending cold air forming high pressure. This air then moves back to the equator or shifts towards the 60° latitude.  Warm air can hold more moisture and so dry winds occur making atmospheric conditions very dry. Continental deserts are found far inland, for example Central Australia.  These areas rarely see rainfall as most has been dropped or evaporated by the winds before they reach them.
Soil Characteristics
The soils are generally known as aridisols. They are fine / sandy in texture to gravely / coarse. They have very little sub-surface horizon development. Low-lying areas tend to have deep soils from millennia of weathering in the highlands where soil is washed down by the rain. The soils are poorly developed due to the lack of rain. They have a high mineral content but low organic content. This means the soils end up being greyish in colour. The soils are easily eroded and allow for evaporation to occur as they do not hold much water. They tend to be quite alkaline and have hard pans due to calcification. Salinisation also occurs with salt pans developing as a result. 

The related patterns of animal and vegetation distribution are as follows.
Plant Life
The plant life that exists has developed specifically to accommodate for the lack of rainfall. Plant life is sparse in these areas except around oasis. Plants like cactus have deep taproots (some up to 30 m long) to access water, thick waxy skin and spikes for protection from evaporation and protection from predators. Fast growing plants (ephemerals) flourish for 2/3 weeks and return to the ground leaving their seeds. With irrigation, agriculture is possible, e.g. along the Nile, Egypt.
Animal Life
The animals have also adapted to this environment.  An example would be the camel (e.g. Dromedary Camel), which has broad hooves to stop it sinking in the sands and thick pads to protect it from the heat.  Their eyelashes are long to protect their eyes from the dust/sandstorms and their coats are pale to protect them from the sun. They are capable of travelling vast distances without taking water due to their water carrying capacity. Another animal, the roadrunner, runs everywhere as it uses less energy than if it were to fly, thus showing another adaptation to the desert environment.

Smart Tips!

Be able to give examples of the characteristics you describe.

An ecosystem is a community of animals and plants treated as a unit with its physical environment. On a global scale, all the ecosystems of one type are referred to as a biome.  The biome that I have studied is aDesert Biome. The general characteristics are as follows.
Distribution: generally found between 15° + 30° south and north of the equator, e.g. Sahara.  Deserts tend to lie on the western margins or in the centre of continents.  There are also some deserts in mid-latitudes between 30° + 40° north and south of the equator.  These are found within the continental interiors, e.g. Gobi.  Deserts can be very arid, arid and semi-arid.  This can depend on a number of factors including: high-pressure belts, rain shadows, cold ocean currents and continentality (distance from the sea).
Most deserts are global locations where high-pressure belts exist (15° to 30° north and south of the equator).  The air that is heated rises at the equator, moves northward and southward until the air contracts, becomes dense and falls to earth at about the 30° latitude.  Compression warms the descending cold air, forming high pressure. This dense, dry air then moves back to the equator or shifts towards the 60° latitude.  The warm air can hold more moisture and so dry winds occur and atmospheric conditions are very dry.
The weather here is usually very stable in that there are clear skies and little rainfall. Typically less than 100mm of rain a year = desert. The diurnal range is very high. Daytime temperatures can reach 50° and night temperatures can go down to 0°.  The rain shadow effect produced by high mountains can create deserts, for example, the Gobi desert north of the Himalayas.  Here the absence of rainfall creates the arid environment that prevails in this climate type. 
Deserts are also influenced by cold coastal currents which are moving to the equator from higher latitudes.  These occur on the western fringes of continents, e.g. Kalihari.  Winds that blow over these currents are cooled, decreasing their capacity to hold moisture.  When the air contacts hotter land the air heats and can retain moisture. Thus the coastal region remains desert.
Continental deserts are found far inland, e.g. Central Australia.  These areas rarely if ever see rainfall as most has been dropped or evaporated by the winds before they reach them.
Humans who inhabit these regions historically have been nomads, e.g. the Twareg of North Africa.  They have practised pastoral nomadism for thousands of years and moved with the seasons within these regions.
The plant life that exists has developed specifically to accommodate for the lack of rainfall.  Plants like cactus have deep taproots to access water, thick waxy skin and spikes for protection from predators.  The animals have also adapted suitably to exist in this environment.  An example is the camel, which has broad hooves to prevent sinking in the sands and thick pads to protect itself from the heat.  Camel’s eyelashes are long to protect their eyes from the dust/sandstorms and they are capable of travelling vast distances without taking water.

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