Understanding Monocultures
Human Influences on Ecosystems –
Chapter 19
Cambridge IGCSE Biology (4th
Edition)
What is a Monoculture?
• Definition: Growing a single crop species over
a large area.
• Often used in modern industrial agriculture.
• Leads to reduced biodiversity and ecological
imbalance.
• Example: A rice field with only rice plants.
Advantages of Monocultures
• Efficient large-scale farming with machinery.
• Uniform crop ripening simplifies harvest.
• Standardised size/quality improves
marketability.
• Lower short-term production costs.
Disadvantages of Monocultures
• Biodiversity loss: fewer species can survive.
• Increased pest populations due to abundant
food.
• Heavy pesticide use kills helpful insects too.
• Soil nutrient depletion over time.
• Higher risk of crop failure due to lack of
genetic diversity.
Monoculture vs Diverse
Ecosystems
• Monocultures:
• - Low biodiversity, high pest risk, soil
degradation.
• Diverse Ecosystems:
• - High biodiversity, natural pest control,
healthy soil.
• Diverse systems are more resilient and
sustainable.
Impact on Ecosystems
• 5 million hectares lost to biodiversity (FAO).
• Up to 95% soil fertility decline in monoculture
systems (UNEP).
• Monocultures disrupt ecosystem balance.
• Require more fertilisers and pesticides over
time.
Sustainable Alternatives
• Mixed cropping improves biodiversity and
pest resistance.
• Crop rotation maintains soil fertility and
reduces pests.
• Used historically since 3000 BC and still
effective today.
• Modern agriculture is moving towards these
practices.
Review & Reflection
• 1. What is a monoculture?
• 2. Why are monocultures popular with
farmers?
• 3. What are two environmental drawbacks of
monocultures?
• 4. How does mixed cropping help ecosystems?
• 5. What are the long-term effects of soil
nutrient loss?