OCR GCSE Geography B: Sustaining Ecosystems Tutorial

This tutorial provides a comprehensive overview of the key concepts and topics covered in the Sustaining Ecosystems unit of OCR GCSE Geography B. By the end of this tutorial, you should understand ecosystem components, global biomes, rainforest dynamics, human impacts, and adaptations.

1. Ecosystem Components

Ecosystems are composed of two main types of components: biotic and abiotic.

• Biotic Factors:
  These are the living components of an ecosystem. They include:
• Producers (e.g., plants, algae): Organisms that make their own food using sunlight (photosynthesis).
• Consumers (e.g., animals, insects): Organisms that eat other organisms to gain energy.

• Decomposers (e.g., bacteria, fungi): Organisms that break down dead plants and animals, releasing nutrients back into the ecosystem.

• Abiotic Factors:
  These are the non-living components of an ecosystem. Examples include:

• Sunlight
• Water
• Soil
• Temperature
• Rainfall

Trophic Levels

Trophic levels describe the feeding positions of organisms within an ecosystem. Energy flows through ecosystems in the following sequence:

1. Producers (Trophic Level 1)
2. Primary Consumers (Herbivores, Trophic Level 2)
3. Secondary Consumers (Carnivores, Trophic Level 3)
4. Tertiary Consumers (Top Carnivores, Trophic Level 4)

2. Global Biomes

Biomes are large, naturally occurring communities of plants and animals that occupy specific habitats.

Major Biomes Covered:

1. Tropical Rainforest (TRF)
2. Climate: High temperature and high rainfall throughout the year.

3. Organisms: Dense vegetation, broadleaf trees, epiphytes, monkeys, and macaws.

4. Savanna

5. Climate: High temperature, seasonal rainfall (wet and dry seasons).

6. Organisms: Grasses, acacia trees, giraffes, lions, and zebras.

7. Desert

8. Climate: High temperature, very low rainfall.

9. Organisms: Cacti, succulents, snakes, and insects.

10. Temperate Forest

11. Climate: Moderate temperature, seasonal rainfall.

12. Organisms: Deciduous or coniferous trees, deer, and squirrels.

13. Tundra

14. Climate: Very low temperature, short growing season, low rainfall.

15. Organisms: Low-growing shrubs, mosses, reindeer, and arctic foxes.

16. Coral Reefs

17. Climate: Warm, shallow coastal waters.
18. Organisms: Coral polyps, fish, sea turtles, and mollusks.

3. Rainforest Focus

Tropical rainforests are one of the most biodiverse ecosystems on Earth.

Canopy Layers

Rainforests are divided into distinct layers:
1. Emergent Layer: The tallest trees (e.g., kapok) that rise above the canopy.
2. Canopy Layer: The dense upper layer of trees where most birds, monkeys, and epiphytes (e.g., orchids) are found.
3. Understory Layer: A darker layer with smaller plants and shrubs.
4. Forest Floor: The ground layer, where decomposition occurs and larger animals like tapirs and jaguars are found.

Nutrient Cycling

Rainforests rely on rapid nutrient cycling due to high rainfall and warm temperatures.
- Decomposers quickly break down dead plant and animal matter, returning nutrients to the soil.
- Nutrients are absorbed by plant roots and used for growth.

Convectional Rainfall

Rainforests create their own rainfall through convection:
1. Solar energy heats the ground, causing water to evaporate.
2. Water vapor rises, cools, and condenses into clouds.
3. Rain falls back to the ground, maintaining the moisture cycle.

Interdependence

Rainforests are highly interdependent systems. For example:
- Trees provide shade for smaller plants.
- Pollinators (e.g., bees) help flowers reproduce.
- Symbiotic relationships (e.g., fungi and tree roots) are common.

4. Human Impacts on Ecosystems

Human activities have significant impacts on ecosystems, particularly in rainforests.

Logging

• Impact: Removes large areas of trees for timber, leading to habitat loss and soil erosion.
• Consequence: Reduction in biodiversity and increased risk of extinction for forest species.

Slash-and-Burn

• Impact: Forests are cut and burned to clear land for agriculture or livestock.
• Consequence: Loss of biodiversity, soil degradation, and increased greenhouse gas emissions.

Mining

• Impact: Mining in rainforests can lead to deforestation and water pollution.
• Consequence: Disruption of local ecosystems and harm to aquatic life.

Costa Rica Ecotourism Model

• Costa Rica has successfully implemented sustainable tourism to protect its rainforests.
• Activities like zip-lining, wildlife watching, and hiking generate income while preserving ecosystems.
• This model promotes conservation and provides livelihoods for local communities.

5. Adaptations

Plants and animals in ecosystems have evolved specific adaptations to survive and thrive.

Plant Adaptations

• Buttress Roots: Found in rainforest trees to stabilize them on shallow soil.
• Drip Tips: Long, pointed leaves that allow excess water to run off quickly, preventing fungal growth.

Animal Adaptations

• Camouflage: Many rainforest animals, such as jaguars and sloths, have coloring or patterns that blend into their surroundings.

6. Conclusion

Understanding ecosystems, biomes, and the interactions within them is crucial for sustainable management of our planet. Rainforests, in particular, play a vital role in global climate regulation and biodiversity. Human activities must be balanced with conservation efforts to ensure the long-term health of ecosystems.