Comprehensive Geography Revision Guide: Extreme Environments, Map Skills, Settlement, and Tourism

Extreme Environments: Tropical Rainforests

Extreme environments are defined by specific keywords and geographical characteristics. Distribution refers to where something is found. Convectional rainfall is a key process in Tropical Rainforests, driven by evaporation (liquid turning to gas), condensation (vapour cooling to liquid), and precipitation (rain, snow, sleet, or hail). The temperature range is the difference between the highest and lowest temperatures. To survive, organisms use adaptation. In the rainforest, this involves specific flora like emergents (tallest trees), Buttress roots (massive ridges for support), epiphytes (plants growing on others), lianas (woody vines), and Drip tips (pointed leaf ends). Drought refers to a prolonged period of lack of rain, while succulents are plants that store water.

Tropical Rainforests are primarily located near the equator in Central and South America, parts of Africa, and Asia. Geographically, they are found between the Tropic of Cancer and the Tropic of Capricorn. Specific countries containing these forests include Brazil, Thailand, Madagascar, and Indonesia. This distribution is explained by the global atmospheric circulation model, where the sun is overhead all year at the equator, creating a hot and humid equatorial climate. The mean monthly temperature stays between $22-28\,^{\circ}C$ , and the annual rainfall is high at approximately $2000\,mm$ , leading to high humidity.

Climate and Rainfall Processes

The climate of the Tropical Rainforest is characterized by convectional rainfall. The process occurs in several steps: First, heat from the sun warms the ground. Second, the air above the ground also warms up. Third, currents of warm air rise, known as convection currents. Fourth, as the rising air begins to cool, water vapour begins to condense, forming clouds. Finally, this process continues until it starts to rain. On a climate graph, the temperature is represented by a red line and precipitation is shown by blue bars. In a typical rainforest climate, the temperature remains steady all year round without dramatic changes, and while some months have more rainfall (such as March), there are no months with zero rainfall.

Rainforest Vegetation and Adaptations

The rainforest is divided into distinct horizontal layers. The Forest Floor receives very little light, and only plants adapted to low light grow there. A thin layer of fallen leaves and debris decomposes rapidly; a leaf that takes a year to break down in other climates will decompose here in only $6\,weeks$ . The Undercanopy reaches about $10\,m$ and receives only $2-15\%\text{ of the sunlight}$ that the canopy gets, resulting in plants adapted to shade and almost no wind. The Canopy is a thick layer at $25-45\,m$ height where leaves are often enormous (some up to $7\,m$ across) to absorb sunlight. Emergents are the tallest trees, reaching $50-65\,m$ ; there are only $1-2$ per acre, and they face dry conditions due to bright sun and strong winds.

Specific plant adaptations include:

Buttress Roots: These are massive ridges stretching $2\,m$ or more up the trunk. Since rainforest soil is shallow and nutrients are at the surface, these roots provide the necessary stability for tall trees and help transport water and gas ( $O_2/CO_2$ ) through increased surface area.
Lianas: Woody creepers rooted in the ground that climb trees to reach the canopy to maximize sunlight.
Epiphytes: Plants that live on the branches or trunks of other plants to reach sunlight and feed on nutrients from rotting leaves.
Drip-tips: Leaves with smooth, glossy surfaces and pointed tips that allow heavy rain to run off quickly. This prevents the growth of algae, which would otherwise block sunlight and stop photosynthesis.
Flexible Bases: Allow leaves to turn and face the sun.
Thin Smooth Bark: Allows water to flow easily and prevents other plants from growing on the tree surface.
Fast-growing trees like the Capoc: These out-compete others to reach the sunlight.

Animal Adaptations in the Rainforest

Animals in the rainforest have evolved specialized traits to survive and avoid competition:

Poison Dart Frogs: They use bright colors to warn predators of their toxicity. Some non-poisonous species mimic these colors to remain unharmed.
The Jaguar: The world's largest cat species, it grows to less than $6\,feet$ long and weighs about $200\,pounds$ . This small, muscular build allows it to move through dense vegetation and achieve the speed needed to hunt.
Toucan: To avoid competition, they have a specialized diet of fruits that other species cannot access. Their beaks are long and narrow, specifically adapted to crack these fruits open.
Spider Monkeys: They live in the tree canopy to avoid competition in the understory. They have developed prehensile tails capable of grasping, allowing them to swing freely among branches.

Deforestation: Causes and Effects

Deforestation is the action or process of clearing forests. Major causes include:

Mining for metals: It is estimated that more than $200,000$ gold miners work in the Brazilian Amazon. The Carajas iron ore project alone will destroy $16\%$ of the Amazonian rainforest.
Cattle ranches: Large areas are cleared to grow meat for export to markets like North America.
Building HEP Dams: Huge hydroelectric power projects flood large areas, killing animals and drowning forests.
Selling wood (timber): Hardwoods like mahogany are shipped to More Economically Developed Countries (MEDCs) for furniture.
Farmland for the poor: Impoverished families in Brazil often clear forest for farming as an alternative to starvation or overcrowded cities.

The effects of deforestation are significant, leading to the loss of biodiversity, the displacement and loss of indigenous tribes, increased flooding, and global warming.

Hot Deserts: Characteristics and Adaptations

Hot deserts are typically found between $15-30\,^{\circ}N$ and $15-30\,^{\circ}S$ of the equator, often on the western edges of continents. Examples include the Sahara and the Thar Desert. A desert is defined as an area receiving less than $250\,mm$ of precipitation per year. Temperatures fluctuate dramatically from $40\,^{\circ}C+$ during the day to below $0\,^{\circ}C$ at night due to the lack of cloud cover. Deserts typically have only two seasons: summer and winter. Aridity is the primary factor controlling life.

For the Jaisalmer station in the Thar Desert, Rajasthan, India, the monthly precipitation data ( $mm$ ) is as follows:

Jan: $8\,mm$ , Feb: $5\,mm$ , Mar: $3\,mm$ , Apr: $4\,mm$ , May: $15\,mm$ , Jun: $23\,mm$ , Jul: $59\,mm$ , Aug: $53\,mm$ , Sep: $49\,mm$ , Oct: $12\,mm$ , Nov: $1\,mm$ , Dec: $3\,mm$ .

Animal adaptations, such as those of the Camel, include stretchy nostrils and long eyelashes to keep out sand, a leathery mouth to eat spiky plants, a hump for storing food, long legs to stay off the hot sand, and padded feet to prevent sinking.

Plant adaptations in the desert include:

Cactus: Waxy layers to store water, no leaves to prevent transpiration, prickles for protection, and both deep vertical roots (to reach the water table) and horizontal surface roots (to collect surface water).
Elephant Tree: Stores water in a thick trunk and lower limbs; has small branches relative to trunk size.
Organ Pipe Cactus: Found on south-facing slopes, it uses a unique photosynthesis pathway and thick pulpy flesh to store water.
Desert Lily: Prefers sandy dunes and has long floral tubes for pollination by sphinx moths and hummingbirds.
Desert Heather: A shrub $2-3\,m$ tall that is extremely drought-resistant and evergreen.

Desertification: Causes, Effects, and Solutions

Desertification is the process where fertile land turns into desert. This occurs on the edges of existing deserts, such as the Sahel region south of the Sahara. Causes include natural factors like drought and climate change, alongside human actions such as overgrazing, deforestation, and overcultivation.

The effects in the Sahel are widespread: crops fail, animals die, and families lose income and food. Children may miss school to fetch water, and many people are forced to migrate. Solutions include planting trees to hold soil, controlled grazing to allow grass recovery, collecting rainwater, crop rotation, and using stone lines to slow rainwater and prevent soil erosion.

Map Skills: Terminology and Techniques

Understanding maps requires mastery of key terms:

Settlement: A permanent or semi-permanent community.
Direction: The path along which something faces (e.g., North, NE, East, SE, South, SW, West, NW).
Relief: The variations in elevation of the Earth's surface.
Scale: The level at which a phenomenon is measured.
Grid Referencing: 4-figure grid references find an area, while 6-figure references find a specific point. Always read "along the corridor (bottom left) and up the stairs."

Height on a map is shown in three ways:

Spot Heights: A black dot with a number showing exact meters above sea level.
Layer Shading: Different colors represent height ranges (e.g., brown for high ground, green for low), requiring a key.
Contour Lines: Lines connecting points of equal height. Lines close together indicate a steep slope, while lines far apart indicate a gentle slope.

Settlement: Site Selection and Patterns

The site of a settlement is the actual place where it grew. Early sites were chosen for natural advantages: building materials (wood/stone), fuel (wood), protection (hilltops for views), water supply (rivers/springs), non-marshy dry land, shelter (south-facing slopes for sun), and flat land for building and farming.

Settlement functions (the reason it was first built) include:

Market Town: For buying and selling goods.
Industrial Town: Centered on manufacturing and production.
Port: A harbor for loading/unloading ship cargo.
Resort: A place for vacations and relaxation.

Settlement patterns describe their shape: Linear (along a road/river), Dispersed (spread out), Isolated (single buildings), or Nucleated (clustered around a center).

Tourism: Growth, Attractions, and Impacts

Tourism is increasing due to more leisure time, improved/faster transport, lower costs, more paid leave, and longer life expectancy. Attractions are categorized as physical (natural features like beaches, mountains, climate) or human (man-made features like theme parks, castles, or the Burj Khalifa in Dubai).

Mass tourism involves large-scale travel to one region. For example, Kenya attracts visitors for its wildlife (Masai Mara), mountains (Mt Kenya, $5199\,m$ ), and coastal resorts (Mombasa).

Positives of tourism include job creation, foreign investment, and improved infrastructure (roads, airports, power). Negatives include seasonal low-pay jobs, rising living costs for locals, environmental damage (litter, pollution, habitat destruction), and social issues like noise or displacement of indigenous people.

Questions & Discussion

Task 1: Location of Rainforests

Question: Name three continents with tropical rainforests.
Answer: South America, Africa, Asia.
Question: Name any continents with no rainforests.
Answer: Antarctica, Europe.
Question: Describe the distribution of tropical rainforests.
Answer: They are located near the equator, between the Tropics of Cancer and Capricorn.

Plenary Activity: Climate True or False

"The temperature changes dramatically throughout the year": False.
"The month with the most rainfall is March": True.
"In some months there is no rainfall": False.
"The temperature is mild throughout the year": False (It is hot).
"The temperature is steady all year round": True.

Map Skills Challenge

Question: How do you find a 4-figure vs 6-figure grid reference?
Answer: 4-figure represents the square/area; 6-figure identifies the specific point within that square.

Exam Skills and Revision Guidance

For long answer questions, use the "Make a point, because, leads to, therefore" structure. Use PEEL paragraphs:

P (Point): One clear point answering the question.
E (Evidence): A specific fact, statistic ( $16\%$ , $2000\,mm$ ), or case study (Kenya, Dubai, Amazon).
E (Explain): Use phrases like "This means that" or "As a result" to explain why the evidence proves the point.
L (Link): Direct the paragraph back to the original question.

Revision techniques include flashcards, mind maps, revision clocks, and practice quizzes. Useful websites include BBC Bitesize, Ordnance Survey Mapzone, and Seneca Learning.