IB MYP 4-5 Biology-Habitat change or destruction- Study Notes - New Syllabus
IB MYP 4-5 Biology-Habitat change or destruction- Study Notes – New syllabus
IB MYP 4-5 Biology-Habitat change or destruction- Study Notes – IB MYP 4-5 Biology – per latest IB MYP Biology Syllabus.
Key Concepts:
- Deforestation (tropical rainforest case study)
- Wetland drainage and consequences
- Coral reef degradation
- Fragmentation effects on biodiversity
Deforestation (Tropical Rainforest Case Study)
What Is Deforestation?
Deforestation means clearing or cutting down forests, often to make space for farming, buildings, or roads.
It’s a major environmental issue especially in tropical rainforests, which are home to most of the world’s biodiversity.
Tropical Rainforests: Why They Matter
- Found in Amazon (South America), Congo (Africa), Southeast Asia
- Hot, wet climate supports dense vegetation and millions of species
- Often called the “lungs of the Earth” because they absorb CO₂ and release oxygen
Case Study: The Amazon Rainforest (Brazil)
Location:
Covers over 5.5 million km² in South America – 60% lies within Brazil
Main Causes of Deforestation:
| Cause | Explanation |
|---|---|
| Cattle Ranching | Trees cleared for grasslands to raise livestock |
| Logging | Cutting trees for timber and export |
| Soybean Farming | Forests cleared for large-scale agriculture |
| Mining | Forest land used for gold, bauxite, etc. |
| Road Building | Roads (e.g., Trans-Amazonian Highway) cut through forest |
| Urban Development | Expanding cities and settlements |
Impacts of Deforestation
- Loss of Biodiversity: Rainforests contain over 50% of all species. Habitat loss → extinction risk rises.
- Disruption of Water Cycle: Fewer trees = less evapotranspiration → drier climate & reduced rainfall.
- Soil Erosion: Tree roots hold soil. Without them, soil washes away → poor fertility.
- Climate Change: Trees store carbon. Cutting them releases CO₂ → warming Earth.
- Impact on Indigenous People: Tribes lose land, culture, and face conflicts with industries.
Solutions and Conservation Efforts
| Strategy | Description |
|---|---|
| Reforestation | Planting new trees to replace those lost |
| Sustainable logging | Only selected trees cut, avoids clear-cutting |
| Protected areas | National parks and forest reserves |
| Eco-tourism | Tourism that benefits and funds conservation |
| International support | Countries (e.g., Norway) fund forest protection |
| Education | Teaching locals and global citizens to value forests |
Tropical rainforests like the Amazon are vital for biodiversity, climate regulation, and the water cycle.
Human activities like logging and farming are causing massive destruction.
With global cooperation, sustainable practices, and education, we can protect these precious ecosystems.
Wetland Drainage and Consequences
What Are Wetlands?
Wetlands are areas where the land is covered with water, either permanently or seasonally. They include swamps, marshes, bogs, floodplains, and mangroves.
They are often called “Earth’s kidneys” because they filter water, support biodiversity, and prevent floods.
Why Are Wetlands Important?
- Biodiversity hotspots – Home to fish, frogs, birds, insects, and rare plants
- Natural water filters – Remove pollutants and sediments
- Flood control – Absorb excess rainwater and prevent waterlogging
- Carbon storage – Trap carbon in soils and vegetation
- Livelihoods – Support farming, fishing, and eco-tourism
What Is Wetland Drainage?
Wetland drainage is the process of removing water from wetlands to use the land for farming, buildings, or infrastructure. Methods include digging ditches, building dams, or using pumps.
Why Do Humans Drain Wetlands?
| Purpose | Explanation |
|---|---|
| Agriculture | To convert wet areas into farmland |
| Urban development | For housing, roads, and industries |
| Pest control | Reduce mosquitoes and insects |
| Mining or resource use | Extract peat, minerals, or groundwater |
Consequences of Wetland Drainage
- Loss of Biodiversity: Animals lose nesting grounds; migratory birds lose stopover sites.
- Increased Flooding: Without wetlands, excess water floods cities and farmland.
- Water Pollution: Pollutants go straight into rivers and lakes without natural filtration.
- Climate Change: Drained wetland soils release CO₂ and methane into the atmosphere.
- Soil Degradation: Soils dry, crack, and may turn salty or infertile (salinization).
Real-Life Example: Kolleru Lake, India
Kolleru Lake was once one of India’s largest freshwater lakes (Andhra Pradesh).
Drained for aquaculture and paddy fields → led to bird loss, fishery collapse, and frequent flooding.
Can Wetlands Be Restored?
- Ramsar Convention: International treaty to protect and conserve wetlands
- India’s Wetland Rules (2017): Identify and conserve ecologically important wetlands
- Creating buffer zones and replanting native wetland vegetation
- Removing pollutants and managing water flow naturally
Wetlands are vital ecosystems that support life, filter water, and protect us from floods.
Draining them for farming or urban use causes biodiversity loss, water pollution, and carbon release.
Protecting and restoring wetlands is essential for a healthy, sustainable planet.
Coral Reef Degradation
What Are Coral Reefs?
Coral reefs are underwater structures built by tiny animals called coral polyps. Found in warm, shallow tropical seas, they’re often called the “rainforests of the sea” due to their biodiversity.
Why Coral Reefs Matter
- Biodiversity hotspots – Home to over 25% of marine species
- Natural barriers – Protect coasts from waves and erosion
- Medical value – Coral organisms help in drug discovery
- Fisheries & food – Essential for millions of livelihoods
- Tourism income – Attract divers and eco-tourism
What Is Coral Reef Degradation?
Degradation refers to the decline in coral health due to human and natural factors.
| Cause | How It Affects Reefs |
|---|---|
| Climate change | Warmer oceans cause coral bleaching |
| Ocean acidification | CO₂ increases acidity → weakens coral skeletons |
| Pollution | Chemicals, sewage, and plastic damage coral health |
| Overfishing | Disrupts reef food webs and predator-prey balance |
| Dynamite/cyanide fishing | Physically destroys reef structures |
| Tourism pressure | Anchors, trampling, and sunscreen harm corals |
Corals have algae (zooxanthellae) living inside them which give them color and energy.
Stress (heat, pollution) → algae are expelled → coral turns white = bleaching.
Prolonged bleaching leads to coral death.
Real-Life Examples
| Reef System | Location | What’s Happening |
|---|---|---|
| Great Barrier Reef | Australia | Mass bleaching events (2016–2020) |
| Andaman & Nicobar | India | Coral loss from tsunami and warming |
| Caribbean Reefs | Central America | Pollution and tourism threats |
Consequences of Reef Degradation
- Loss of marine biodiversity
- Decline in fisheries → impacts food security
- More coastal erosion due to reef loss
- Tourism and economic losses
- Disruption of ocean ecosystems → climate feedback
How Can We Protect Coral Reefs?
| Action | Details |
|---|---|
| Local Actions | Reduce pollution, promote reef-safe tourism, regulate fishing |
| Global Actions | Cut carbon emissions, expand marine reserves, restore coral |
Coral reefs are vital to marine ecosystems and coastal communities.
Threats like climate change, pollution, and fishing are causing rapid degradation.
Protecting reefs requires both global action and local responsibility.
Fragmentation Effects on Biodiversity
What Is Habitat Fragmentation?
Habitat fragmentation happens when a large, continuous natural habitat is broken into smaller, isolated patches. This usually occurs due to roads, farming, urban development, or deforestation.
Why Does Fragmentation Happen?
| Human Activity | How It Fragments Habitats |
|---|---|
| Roads & highways | Split ecosystems into separate sections |
| Farming expansion | Clears forests into small crop plots |
| Urban sprawl | Cities grow and push wildlife out |
| Construction projects | Buildings, dams, railways cut across nature |
Main Effects on Biodiversity
- Isolation of Species: Populations become cut off, leading to inbreeding and lower genetic diversity.
- Loss of Habitat Area: Smaller patches support fewer species – some disappear entirely.
- Edge Effects: Harsher conditions at habitat edges reduce usable space even more.
- Increased Vulnerability: Isolated populations are at higher risk from disasters, disease, or poaching.
- Disruption of Migration: Fragmentation blocks animal movement and leads to human-wildlife conflict.
Real-Life Examples
| Region | Fragmentation Impact |
|---|---|
| Western Ghats, India | Roads and tea plantations split forest patches |
| Amazon Rainforest | Logging and farming divide habitats |
| African Savannah | Fences and farms disrupt herbivore movement |
| US Highways & Forests | Wildlife-vehicle collisions and blocked migration |
How Does It Affect Ecosystems?
- Food chains break down
- Pollination and seed dispersal drop
- Ecosystems become unstable and less resilient
What Can Be Done?
| Conservation Method | Benefit |
|---|---|
| Wildlife corridors | Connect isolated patches and allow safe animal movement |
| Reforestation | Reconnects fragmented habitats |
| Protected areas | Minimizes human disruption in fragile zones |
| Awareness & laws | Encourages eco-friendly development and policy changes |
Fragmentation splits natural habitats into smaller, isolated parts.
This harms biodiversity by isolating species, breaking food webs, and reducing survival.
We can reduce its effects through corridors, reforestation, and smart planning.