1.9.3Inquiry Process
Ecosystem Loss — IB Biology HL Revision Notes & Topical Questions
5 min read 6 parts Lesson 34 of 160
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Part 1 of 6Causes of Ecosystem Loss
Deforestation
- Deforestation Forests are cleared for farmland, palm oil, cattle ranching and timber, especially in tropical regions.
Wetland drainage
- Wetland drainage Marshes and mangroves are drained or filled for farming, building and aquaculture.
Urbanisation
- Urbanisation Expanding cities and roads cover natural land with concrete and divide remaining habitat.
Coral reef damage
- Coral reef damage Warming seas cause bleaching, while pollution and destructive fishing damage reef structure.
Agriculture
- Agriculture Intensive farming replaces diverse habitats with large monocultures of a few crop species.
Part 2 of 6Fragmentation
Even when some habitat remains, splitting it into small patches reduces its value for wildlife.
Fragmentation
Edge effect
- Edge effect Habitat near edges has different light, wind and predators, so interior specialists cannot survive there.
Isolation
- Isolation Small separate patches limit movement, reduce gene flow and increase inbreeding.
Corridors
- Corridors Strips of habitat linking fragments allow animals and plants to move between patches.
Area requirement
- Area requirement Large predators need big territories and are usually the first to disappear.
Part 3 of 6Consequences
1
Species lose food and shelter, so their populations fall or they become locally extinct.
2
Loss of trees increases soil erosion and can alter rainfall patterns.
3
Carbon stored in forests and peat is released as carbon dioxide, adding to climate change.
4
Coastal protection decreases when mangroves and reefs are damaged.
5
People lose services such as clean water, fisheries and timber.
| Ecosystem | Loss driver | Service lost |
|---|---|---|
| Rainforest | Clearing | Carbon storage |
| Mangrove | Aquaculture | Coastal protection |
| Coral reef | Warming | Fish nurseries |
Part 4 of 6Reducing Ecosystem Loss
Sustainable farming
- Sustainable farming Mixed crops, hedgerows and reduced clearing keep more habitat on working land.
Certification
- Certification Labels for sustainable timber and palm oil let buyers avoid products from newly cleared forest.
Restoration
- Restoration Replanting native trees and restoring wetlands rebuilds habitat and reconnects fragments.
Protected status
- Protected status Legal protection of key habitats stops conversion to other uses when properly enforced.
Part 5 of 6Worked Example
Question
- A forest of 5000 hectares is cut by roads into 5 equal fragments of 1000 hectares each.
- Discuss the effect on a species that needs 1500 hectares of continuous forest.
- Each fragment is 5000 ÷ 5 = 1000 hectares, which is less than the 1500 hectares needed.
- Individuals cannot find enough territory or food in any one fragment.
- Edge effects increase, because wind, light and predators penetrate fragments more.
- Isolation prevents movement between fragments, reducing gene flow and increasing inbreeding.
Answer The species is likely to decline or disappear because no fragment is large enough, despite the total area being unchanged in the fragments.
Part 6 of 6Exam Checklist & Tips
1.9.3 – Key Points for the Exam
- Deforestation Permanent removal of forest.
- Habitat fragmentation Division of habitat into smaller isolated patches.
- Edge effect Changes in conditions near the border of a habitat.
- Ecosystem services Benefits people obtain from ecosystems.
Common Mistakes
- Thinking that total area is all that matters, ignoring fragmentation.
- Saying forests only store oxygen; they also store carbon and regulate water.
- Forgetting that replanted monoculture is not the same as natural forest.
- Assuming ecosystem loss affects only wildlife and not people.
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