Human impact on ecosystems
A growing human population increases demand for food, land and resources, damaging ecosystems in several ways.
Remember
- Deforestation: less habitat, more CO₂, soil erosion, reduced biodiversity.
- Eutrophication: excess fertiliser or sewage enriches water.
- Pollution: non-biodegradable plastics, sewage and gases such as those causing acid rain.
Eutrophication step by step
Worked example
1) Fertiliser runs off into a lake. 2) Nitrates cause rapid growth of algae (an algal bloom). 3) The algae block light, so plants below die. 4) Decomposer bacteria feed on the dead material and multiply. 5) These bacteria use up the dissolved oxygen in aerobic respiration, so fish and other animals suffocate and die.
Conservation
Conservation protects species and habitats so that biodiversity and useful resources are maintained for the future - this is sustainable use.
Key idea
Methods include recycling materials, captive breeding of endangered species, protecting habitats (reserves), replanting forests, and controlling harvesting with fishing quotas and mesh-size limits so populations can recover.
Conserving biodiversity keeps food webs stable, protects sources of medicines and food, and maintains ecosystems that humans depend on. Burning fossil fuels also releases carbon dioxide and methane, greenhouse gases that trap heat and drive global warming and climate change, while sulfur dioxide dissolves in rain to form acid rain that damages trees, lakes and buildings. Reducing these emissions, treating sewage before release, and using fertilisers carefully are all part of protecting ecosystems for the future.