Relationships Of Organisms With One Another And With The Environment: Effects Of Humans On Ecosystems
19.4 Effects Of Humans On Ecosystems
Deforestation
- Causes: Logging, farming, urbanisation.
- Consequences:
- Loss of biodiversity, extinction.
- Soil erosion and loss of fertility.
- Flooding risk ↑.
- Increased CO₂ in atmosphere → global warming.
Over-Harvesting & Introduced Species
- Over-harvesting: Depletes plant/animal populations.
- Introduced species: Non-natives disrupt ecosystems, outcompete natives.
Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course
Pollution
Water Pollution (sewage, fertilisers)
- Extra nitrates → eutrophication.
- Algal bloom → blocks light.
- Decomposition ↑ → less oxygen.
- Aquatic life dies.
Air Pollution (greenhouse gases)
- CO₂, methane → enhanced greenhouse effect → global warming.
Chemicals
- Insecticides/herbicides → accumulate in food chains (bioaccumulation).
- Plastics → non-biodegradable, harm aquatic & terrestrial organisms.
Key Points
- Human activity majorly disrupts ecosystems.
- Effects often long-term and hard to reverse.
- Conservation and sustainable practices reduce harm.
Written And Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions And 11 World Records For Educate A Change O Level And IGCSE Biology Full Scale Course