AQA GCSE Physical Geography: Ecosystems, Tropical Rainforests, and Cold Environments

Comprehensive practice flashcards covering AQA GCSE Physical Geography topics on ecosystem interactions, freshwater ponds, tropical rainforest characteristics and deforestation, as well as tundra/polar adaptations and cold environment management case studies (Svalbard and Alaska).

What is the difference between biotic and abiotic features in an ecosystem?

Biotic features are the living components of an ecosystem, such as plants and animals. Abiotic features are the non-living components, such as soil or climate.

According to the lecture notes, what are the two main sources of nutrients in nutrient cycling?

1. Rainwater washing chemicals out of the atmosphere.
2. Weathered rock releasing nutrients into the soil.

Based on this small-scale pond ecosystem diagram, what are the five distinct zones and the characteristic wildlife found in each?

1. Pond bottom: decomposers and scavengers (e.g., water worms, rat-tailed maggots).
2. Mid water: predators breathing through skin or gills (e.g., stickleback fish, water fleas, dragonfly nymphs).
3. Pond surface: animals breathing through gills, skin, or lungs (e.g., ducks, water boatmen, midge larvae, tadpoles).
4. Pond margin: plants providing sheltered habitats for insects and small animals (e.g., marsh marigold, frogs).
5. Above the pond surface: birds and insects (e.g., kingfishers, dragonflies).

What chain reaction of events occurs in a pond ecosystem if perch fish are introduced?

The perch eats small fish and frogs, leaving insufficient food for top predators like the heron. With frogs gone, there is a population explosion of snails and small creatures that frogs normally consume, creating an ecosystem imbalance.

What caused the degradation of the lake at Avington Park, and what was done in $2014$ to restore it?

A lack of maintenance caused silt accumulation (which depleted oxygen) and excessive vegetation growth, blocking views of the lake. In $2014$, restoration involved desilting, redefining the lake, and creating new waterside habitats for nesting birds and waterfowl.

How do agricultural fertilisers disrupt freshwater ecosystems?

Nitrates from fertilisers leach into the water, causing eutrophication: rapid algal growth that blocks light and depletes oxygen, leading to the death of fish.

What atmospheric process causes the equatorial climate to receive high levels of convectional rainfall?

The Sun heats the land, which warms the air directly above it. The warmed air expands and rises; as it ascends, it cools and condenses to form clouds, ultimately producing heavy rain.

Where are tropical rainforests located, and what percentage of the world's plant and animal species do they support?

They are located along the equator between $23.5^\circ\text{N}$ (Tropic of Cancer) and $23.5^\circ\text{S}$ (Tropic of Capricorn). Although covering only $6\%$ of the Earth's land surface, they house more than half ($>50\%$) of all plant and animal species.

Why are tropical rainforest soils surprisingly infertile despite the dense vegetation?

Heavy daily rainfall rapidly washes nutrients away through leaching, and the dense, luxuriant vegetation rapidly absorbs any available nutrients from the topsoil.

What role does the forest canopy play in the rainforest water cycle?

The canopy intercepts rainfall by catching water on leaves before it hits the ground. Some water evaporates back into the atmosphere via evapotranspiration, recycling moisture to produce more convectional rainfall and sustain the humid climate.

What are the four main vertical layers of a tropical rainforest shown in this diagram?

1. Emergent Layer: Tallest trees reaching up to $60\,\text{m}$ ($200\,\text{feet}$).
2. Canopy Layer: Dense continuous roof of trees $25\text{--}40\,\text{m}$ tall, blocking $80\%$ of sunlight.
3. Understory Layer: Shaded, humid layer $2\text{--}10\,\text{m}$ tall receiving only $2\text{--}5\%$ of sunlight.
4. Forest Floor: Ground layer receiving less than $2\%$ of sunlight, where rapid decomposition occurs.

How are drip tip leaves adapted to the tropical rainforest environment?

They have pointed ends and waxy surfaces that allow water to run off quickly. This prevents waterlogging, fungal and bacterial rot, and protects leaves from breaking under the weight of water, preserving photosynthetic ability.

How do lianas and epiphytes adapt to survive the low-light conditions of the lower rainforest layers?

Lianas are woody vines rooted in the ground that climb trees using twining stems, tendrils, and adhesive roots to access canopy sunlight. Epiphytes grow non-parasitically on other plants, using aerial roots with velamen and cup-shaped leaves to collect water and nutrients directly from rain and debris.

What are the functions of buttress roots in tropical rainforest trees?

They provide massive structural support to anchor tall trees in thin soils against high winds, and spread widely across the surface to maximize absorption of nutrients before they leach away.

What environmental and social impacts resulted from the Bakun Dam project in Sarawak, Malaysia?

The $\$2\,\text{billion}$ hydroelectric project flooded $700\,\text{km}^2$ of forest and farmland, required cutting down approximately $230\,\text{km}^2$ of forest, and forced about $9{,}000$ indigenous Kenyah people to relocate.

What natural processes cause deforestation as outlined in the notes?

1. Volcanism (blast effects, pyroclastic flows, lava, ash; e.g., Mt St. Helens, 1980).
2. Landslides (mass movement of slopes).
3. Drought (forest retreat at desert margins).
4. Rising sea levels (inundation and saltwater intrusion into groundwater).
5. Increasing disease (e.g., Dutch Elm disease, pine bark beetle in western Canada).
6. Wildfires (extended by dry summers in SW Australia, Mediterranean Europe, California).

What is the difference between primary and secondary forests in selective logging systems?

Primary forests consist of undisturbed native trees with high biodiversity. Secondary forests are replanted areas where valuable mature trees (such as mahogany) were removed; they initially have lower biodiversity but can be sustainably managed.

How does a debt-for-nature swap support rainforest conservation?

A donor nation reduces or cancels debt owed by a lower-income country in exchange for the debtor nation agreeing to conserve and protect designated areas of rainforest (e.g., the USA reducing debt owed by Peru).

What is permafrost, and how deep can it extend in tundra environments?

Permafrost is a permanently frozen layer of soil and rock beneath the Earth's surface that traps greenhouse gases. In cold environments, it can extend as deep as $450\,\text{m}$.

How do precipitation and temperature differ between Old Crow (Yukon, Canada) and McMurdo Research Station (Antarctica)?

Old Crow has warm-season peaks above freezing for $5$ months (reaching $10\text{--}15^\circ\text{C}$) and receives less than $380\,\text{mm}$ of precipitation annually. McMurdo Station is a cold desert with average temperatures constantly below freezing (winter temperatures between $-40^\circ\text{C}$ and $-90^\circ\text{C}$) and precipitation under $100\,\text{mm}$ per year.

How are bearberries and arctic moss adapted to the harsh conditions of the tundra?

They grow low to the ground ($5\text{--}15\,\text{cm}$) to escape freezing winds and absorb surface heat, have small leathery leaves with thick waxy cuticles to reduce water loss, and possess hairy stems/leaves to trap heat.

What key adaptations allow caribou to survive in cold tundra biomes?

A dense undercoat with hollow guard hairs that trap warm air and provide buoyancy; large, split hooves that act like snowshoes, paddles, and scoops for digging lichen; and spiral nasal bones that warm and humidify freezing air before it enters the lungs.

What are the key geographical facts about the Svalbard archipelago shown in this map?

Svalbard is located in the Arctic Ocean between $71^\circ\text{N}$ and $81^\circ\text{N}$ latitude. It comprises $5$ major islands, with Spitzbergen being the largest. The capital is Longyearbyen, and the total human population is approximately $2{,}700$, meaning polar bears outnumber people. $40\%$ of non-frozen land is tundra.

Why is coal mining important to Svalbard despite environmental opposition?

Coal mining is the primary economic activity in Svalbard, employing over $300$ workers directly and in support roles. It supplies fuel to Longyearbyen's power station (the only coal-fired plant in Norway), providing all local domestic and industrial electricity.

Why must water and sewage utility pipes in Svalbard be built above ground?

They are heated to prevent water from freezing and bursting the pipes. Raising and insulating them off the ground prevents their heat from thawing the underlying permafrost and facilitates easy maintenance.

How does the Trans-Alaska Pipeline System (TAPS) overcome the challenges of crossing permafrost, rivers, and wildlife migration routes?

1. Permafrost & Hot Oil: The pipeline is elevated on supports and heavily insulated to prevent oil heat from melting permafrost.
2. Animal Migration: Elevated pipeline sections allow large herds of caribou to migrate freely beneath.
3. Earthquakes & River Crossings: The pipeline travels under river beds to avoid damage and features a zig-zag design that can sway during earthquakes, with automated shut-off valves in case of leaks.

What is the primary strength and main limitation of the Antarctic Treaty?

Strength: It protects the largest wilderness on Earth by reserving it for peaceful scientific research and regulating tourism. Limitation: It lacks legal fines or enforcement mechanisms to penalize signatory nations that fail to comply.