Introduction

An ecosystem is a natural system made up of living organisms and the physical environment they interact with. Ecosystems can be small, such as a pond, or very large, such as a tropical rainforest. All parts of an ecosystem are connected, meaning a change in one part can affect the whole system.

Understanding ecosystems helps geographers explain biodiversity, food chains, nutrient cycling and the impacts of human activity on the natural world.

Key Concepts

What is an Ecosystem?

An ecosystem consists of:

Biotic Components (Living)

  • Plants
  • Animals
  • Insects
  • Bacteria
  • Fungi

Abiotic Components (Non-Living)

  • Water
  • Air
  • Soil
  • Temperature
  • Sunlight

These components interact continuously to support life.

Interdependence

Interdependence means that all parts of an ecosystem rely on one another.

Examples include:

  • Bees pollinate flowering plants.
  • Herbivores depend on plants for food.
  • Carnivores depend on other animals for food.
  • Decomposers recycle nutrients.

If one species is removed, other species may be affected.

Food Chains and Food Webs

Food Chain

A food chain shows how energy is transferred.

Example:

Grass → Rabbit → Fox

Food Web

A food web contains many connected food chains and shows the complex feeding relationships within an ecosystem.

Producers, Consumers and Decomposers

Producers

Plants make their own food through photosynthesis.

Consumers

Animals gain energy by eating plants or other animals.

Types include:

  • Herbivores
  • Carnivores
  • Omnivores

Decomposers

Fungi and bacteria break down dead material and return nutrients to the soil.

Nutrient Cycling

Nutrients move between three main stores:

  • Biomass
  • Litter
  • Soil

Decomposers release nutrients into the soil, which plants absorb and use to grow.

Biodiversity

Biodiversity means the variety of living organisms within an ecosystem.

High biodiversity:

  • Creates stable ecosystems.
  • Increases resilience to change.
  • Supports food webs.
  • Maintains important natural processes.

Factors Affecting Ecosystems

Climate

Temperature and rainfall affect the types of plants and animals that can survive.

Soil

Soil quality influences plant growth and nutrient availability.

Relief

Altitude and landscape shape affect temperature and drainage.

Human Impacts on Ecosystems

Deforestation

  • Habitat destruction
  • Loss of biodiversity
  • Increased soil erosion

Pollution

  • Damages habitats
  • Kills wildlife
  • Reduces water quality

Urbanisation

  • Habitat fragmentation
  • Loss of natural environments

Sustainable Ecosystem Management

Methods include:

  • Conservation schemes
  • Reforestation
  • Protected areas
  • Sustainable farming
  • Ecotourism

These methods aim to protect ecosystems while allowing people to use natural resources responsibly.

GCSE Practice Questions

1 Mark Questions

Q1

What is meant by the term ecosystem?

Q2

Name one biotic component of an ecosystem.

Q3

What process do plants use to make food?

Q4

Name one abiotic component of an ecosystem.

2 Mark Questions

Q5

Give two examples of consumers.

Q6

State two benefits of biodiversity.

Q7

Give two ways ecosystems can be damaged by humans.

Q8

State two components of a food web.

3 Mark Questions

Q9

Explain how decomposers support ecosystems.

Q10

Explain why food webs are more realistic than food chains.

Q11

Describe how nutrients move through an ecosystem.

Q12

Explain why ecosystems with high biodiversity are often more stable.

4 Mark Questions

Q13

Explain the importance of interdependence within an ecosystem.

Q14

Explain how deforestation can affect nutrient cycling.

Q15

Explain how climate influences ecosystems.

Q16

Explain how sustainable farming can help protect ecosystems.

6 Mark Questions

Q17

Assess the importance of biodiversity in maintaining healthy ecosystems.

Q18

Explain the impacts of human activities on ecosystems.

Q19

Using a named ecosystem you have studied, explain its key characteristics and importance.

9 Mark Question

Q20

Evaluate the effectiveness of strategies used to manage ecosystems sustainably.

Answers

Q1

An ecosystem is a community of living organisms interacting with each other and with their physical environment.

Q2

Any one of:

  • Plant
  • Animal
  • Fungi
  • Bacteria

Q3

Photosynthesis

Q4

Any one of:

  • Water
  • Soil
  • Air
  • Sunlight
  • Temperature

Q5

Any two of:

  • Rabbit
  • Deer
  • Fox
  • Lion

Q6

  • Supports ecosystem stability.
  • Helps ecosystems recover from change.

Q7

  • Deforestation
  • Pollution

Q8

  • Producers
  • Consumers

Q9

Decomposers break down dead plants and animals. This releases nutrients into the soil, allowing plants to grow and helping nutrient cycles continue.

Q10

Food webs show many feeding relationships between organisms. Most animals eat more than one species, so food webs provide a more accurate picture of energy transfer.

Q11

Nutrients are released from dead material by decomposers. They enter the soil, are absorbed by plants and then pass through food chains before being recycled again.

Q12

A wide variety of species means ecosystems are less dependent on a single organism. If one species declines, others can often continue performing similar roles.

Q13

Plants, animals and the physical environment depend on each other. Changes to one part of the ecosystem can affect food supplies, habitats and population sizes throughout the system.

Q14

Trees store nutrients in biomass. When trees are removed, nutrient stores decrease and soils may become less fertile due to increased erosion and nutrient loss.

Q15

Temperature and rainfall determine which plants can grow and which animals can survive. Different climates therefore support different ecosystems.

Q16

Sustainable farming reduces environmental damage by limiting chemical use, protecting habitats and preventing soil degradation while maintaining food production.

Q17 (6 Marks)

Biodiversity is essential because it supports food webs, nutrient cycling and ecosystem stability. Ecosystems with many species are generally more resilient to disease, environmental change and natural hazards. A loss of biodiversity can weaken ecosystem functions and reduce long-term sustainability.

Q18 (6 Marks)

Human activities such as deforestation, pollution and urban development can destroy habitats and reduce biodiversity. Food webs may become disrupted and nutrient cycles affected. However, sustainable management can reduce some of these impacts and help ecosystems recover.

Q19 (6 Marks)

Example: Tropical Rainforest

Tropical rainforests are found near the Equator and experience high temperatures and heavy rainfall throughout the year. They contain extremely high biodiversity and complex food webs. They are important because they store carbon, regulate climate and provide habitats for millions of species.

Q20 (9 Marks)

Sustainable management strategies such as conservation, protected areas, reforestation and ecotourism can help reduce environmental damage and preserve biodiversity. Protected areas can safeguard habitats, while reforestation restores degraded land. However, these strategies can be expensive and difficult to enforce. Economic pressures and population growth may also increase demand for natural resources. Overall, sustainable management is effective when multiple strategies are combined and supported by governments, local communities and environmental organisations.