Lecture Notes: Forest Biomes of the Tropics

Introduction to Tropical Forests

• Biodiversity: Greatest biodiversity on Earth; over half of all plant and animal species live here.
• Ecological Role: Known as the "lungs of the world" for absorbing more CO2 and producing more oxygen.
• Conditions: Characterized by constant heat and abundant rain.
• Threats: Faces significant threats, including deforestation and agriculture.

Types of Tropical Forests

• Evergreen Forests:

  • Occur where there is minimal to no dry season or extensive flooding.
  • Trees retain leaves and continue growing throughout the year.

• Seasonal Forests:

  • Have noticeable dry seasons; trees shed leaves to conserve moisture.
  • Found on the periphery of evergreen forests.

Tropical Forest Structure

• Forest Floor:

  • Rapid decomposition of litter due to heat, rain, and scavenger insects.
  • Poor soil quality due to nutrient leaching.
  • Sparse undergrowth due to limited sunlight (2% of sunlight).

• Understorey:

  • Contains shrubs and seedlings; receives 5% sunlight.
  • Develops if canopy gaps appear.

• Canopy:

  • Comprises main tree species, absorbing 90% of light.
  • Houses diverse plant and animal life; includes orchids and liana.

• Emergent Layer:

  • Tall trees reaching up to 70 meters; exposed to sun and wind.

Geographic Distribution

• Americas:

  • Dominant in Central and South America (Amazon Basin).
  • Includes both evergreen and seasonal forests.

• Africa:

  • Congo basin and West African coast; edge of seasonal forests.

• Asia:

  • Indian Subcontinent (seasonal); Western coast of India (evergreen).
  • SE Asia and islands like New Guinea and Borneo (mostly evergreen).

• Oceania and Pacific:

  • Small rainforest bands in northern Australia and Pacific islands.

Biodiversity and Plant Species

• Tree Diversity:
  • High biodiversity; e.g., 375 tree species in Malaysia.
  • Common trees: mahogany, teak, ebony, rosewood.
  • Three subkingdoms: Neotropical, African, and Malesian.

Threats and Conservation

• Deforestation:

  • Driven by logging and agriculture (cattle ranching, palm oil).
  • Examples include Brazil, Bolivia, and SE Asia.

• Conservation Message:

  • Urgency in preventing habitat loss; learn from history of habitat destruction.

Conclusion

• Call to Action:
  • Encouragement to share, comment, and subscribe to the content creator's channel for more educational videos on biomes.

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