What does the biodiversity of an ecosystem measure, and why is a hot desert's low?

It measures the variety of plant and animal species living there, and extreme heat, unreliable rain and poor soils mean only a few highly specialised species can survive.

Why is a hot desert ecosystem described as fragile when its species are so tough?

Its species already live at the limit of what they can tolerate, so a small loss of water or vegetation can push them past it.

Why does keeping too many grazing animals reduce the variety of desert species?

Livestock eat and trample the sparse plants, so the tastiest species vanish first and the animals that fed or sheltered in them disappear too.

How can tourism harm the plants and animals of a hot desert?

Off-road vehicles crush plants and break the fragile crust on the soil surface, while visitors disturb wildlife and use scarce water.

AQA GCSE Geography 8035

Climate Change

Topic overview The evidence, causes and effects of climate change Managing climate change: mitigation and adaptation

Coastal Landscapes in the UKUK landscape option

Topic overview Waves and coastal processes: weathering, mass movement, erosion, transport and deposition Coastal landforms of erosion and deposition Identifying landforms on a stretch of UK coastline Coastal management: hard and soft engineering, and a UK scheme Managing the Holderness coast at Mappleton

Cold EnvironmentsLiving world option

Topic overview Cold environment characteristics, interdependence and adaptations Cold environment biodiversity Opportunities and challenges of developing a cold environment Protecting wilderness: balancing development and conservation

Ecosystems

Topic overview Ecosystems at every scale: interrelationships, balance and global distribution

EnergyResource option

Topic overview Energy surplus and deficit, and why demand is rising The impacts of energy insecurity Strategies to increase energy supply Towards a sustainable energy supply

FoodResource option

Topic overview Food security and insecurity: patterns, causes and impacts Strategies to increase food supply Towards a sustainable food supply

Geographical Applications: Fieldwork Enquiry

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Geographical Skills

Topic overview Atlas maps: coordinates, distributions and patterns Reading thematic maps for physical and human associations OS maps: scale, grid references, distance and direction OS maps: gradient, contours and landscape features OS maps: relief, cross sections and drawing inferences OS maps: transects, landscape description and human activity Comparing maps, sketch maps and photographs Describing landscapes from photographs, and annotating them Choosing and constructing the right graph or chart Completing choropleth, isoline, dot, desire-line and flow maps Reading population pyramids, choropleth and flow-line maps Number, scale, proportion and ratio, and designing data sheets Drawing conclusions from numerical data Averages, spread, percentages and correlation Spotting weaknesses in how data is presented Using maps, fieldwork data and GIS as evidence Using imagery, written, visual and graphical sources Using numerical and statistical information as evidence Framing an enquiry and writing about it Building an argument and reaching a conclusion Issue evaluation: stakeholders, options and a justified decision

Glacial Landscapes in the UKUK landscape option

Topic overview The last ice age in the UK, and glacial processes Glacial landforms of erosion, transport and deposition Identifying landforms in a glaciated UK upland Economic activity, conflict and tourism in glaciated uplands Tourism in the Lake District

Hot DesertsLiving world option

Topic overview Hot desert characteristics, interdependence and adaptations Hot desert biodiversity Opportunities and challenges of developing a hot desert Desertification: causes and how the risk is reduced

Natural Hazards

Topic overview What a natural hazard is, and what affects hazard risk

Resource Management

Topic overview Why food, water and energy matter, and how unequally they are shared Resources in the UK, and the changing demand for food The UK's changing demand for water and energy

River Landscapes in the UKUK landscape option

Topic overview The long and cross profiles of a river, and fluvial processes River landforms from source to mouth Identifying landforms in a UK river valley Flood risk, hydrographs and flood management strategies A UK flood management scheme and its effects

Tectonic Hazards

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The Changing Economic World

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Tropical Rainforests

Topic overview Rainforest characteristics, interdependence and adaptations Rainforest biodiversity Deforestation: rates, causes and impacts Deforestation in the Amazon The value of rainforests and how they are managed sustainably

UK Physical Landscapes

Topic overview The UK's upland areas, lowland areas and river systems

Urban Issues and Challenges

Topic overview Global urbanisation: patterns, trends and what drives them The rise of megacities A major city in a poorer or emerging country, and planning for the urban poor Rio de Janeiro: growth, opportunities and challenges The UK's urban population and a major UK city Bristol: urban change in a major UK city An urban regeneration project Sustainable urban living and urban transport

WaterResource option

Topic overview Water surplus and deficit, and why demand is rising The impacts of water insecurity Strategies to increase water supply Towards a sustainable water supply

Weather Hazards

Topic overview Global atmospheric circulation: pressure belts and surface winds Where tropical storms form, and why The structure of a tropical storm, and the effect of climate change The effects of and responses to tropical storms Reducing the effects of tropical storms Weather hazards in the UK An extreme weather event in the UK, and evidence of more extreme weather

Hot Deserts

Hot desert biodiversity

3 things to know
Paper 1 section B

Overview

Why desert biodiversity is low yet fragile and slow to heal, and the threats from groundwater pumping, overgrazing, tourism, mining, salinisation, restricted ranges and a warming climate.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

How does salinisation of irrigated desert land reduce biodiversity?

Key term

Why does damage to desert vegetation take so long to heal?

Key term

How does taking too much groundwater threaten desert wildlife?

Questions from this subtopic

Each one with the model answer underneath.

1
What does the biodiversity of an ecosystem measure, and why is a hot desert's low?
Model answer
It measures the variety of plant and animal species living there, and extreme heat, unreliable rain and poor soils mean only a few highly specialised species can survive.
2
Why is a hot desert ecosystem described as fragile when its species are so tough?
Model answer
Its species already live at the limit of what they can tolerate, so a small loss of water or vegetation can push them past it.
3
Why does damage to desert vegetation take so long to heal?
Model answer
Growth is limited by scarce water and soil forms extremely slowly, so cleared ground and vehicle tracks can stay bare for decades.
4
How does taking too much groundwater threaten desert wildlife?
Model answer
The water table falls, so springs, oases and wetlands dry up and the deep-rooted trees and shrubs that other species depend on die.
5
Why does keeping too many grazing animals reduce the variety of desert species?
Model answer
Livestock eat and trample the sparse plants, so the tastiest species vanish first and the animals that fed or sheltered in them disappear too.
6
How can tourism harm the plants and animals of a hot desert?
Model answer
Off-road vehicles crush plants and break the fragile crust on the soil surface, while visitors disturb wildlife and use scarce water.

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Coastal Landscapes in the UK

Cold Environments

Ecosystems

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