Biomes, Biosphere to Ecosystems, Energy, Nutrient cycles_2025

BIOSPHERE to ECOSYSTEMS

Topic Overview

• Focuses on the relationship between biosphere and ecosystems.

• Pages covered: 134-161 in textbook.

Biodiversity

• Definition: Biodiversity is considered a significant treasure, necessary to prevent its reduction at all costs. (Quote by Thomas Eisner)

• Importance: A large variety of organisms creates balance in ecosystems.

  • Includes animals, plants, fungi, and microorganisms.

• Levels of Biodiversity:

  • Ecosystem Diversity: Variety of ecosystems within a region.

  • Species Diversity: The range of different species within an ecosystem.

  • Genetic Diversity: Variation of genes within species.

  • Estimates: Between 3 and 30 million species on Earth.

Loss of Biodiversity

• Definition: Decrease in the number of species in an ecosystem.

• Impact on Humans:

  • Food Supply Vulnerability: Overfishing and pests can threaten food security.

  • Freshwater Supplies: Interruptions can lead to shortages.

  • Environmental Vulnerability: Increased susceptibility to natural disasters and zoonotic diseases (animal to human transmission).

• Call to Action: Emphasis on sustainable development to preserve resources and maintain ecological balance.

Understanding Biomes

• Definition: A biome is a geographical region with distinct climate supporting specific flora and fauna.

• Factors influencing biomes:

  • Distinctive climate (temperature and rainfall).

  • Soil type specific to the region.

• Identification: Based on vegetation types (plants) within an area.

• Endemic Species: Species limited to a particular region.

• Classification:

  • Terrestrial Biomes (land).

  • Aquatic Biomes (water).

Biomes in South Africa

• Overview: South Africa hosts 8 terrestrial biomes, remarkably diverse despite its size.

• Main Biomes include:

  1. Fynbos

  2. Desert

  3. Forest

  4. Grassland

  5. Nama-Karoo

  6. Savanna

  7. Thicket

  8. Succulent Karoo

• Study Recommendation: Know locations of these biomes on a map.

The Fynbos Biome

• Biodiversity: Over 8500 species, with high endemism (68% of plants).

• Climate: Cold, wet winters and hot, dry summers.

• Soil Types: Sandy, alkaline coastal soil; further inland it becomes more acidic.

• Flora Characteristics: Low shrubs, fine leaves (e.g., ericas), few trees, adapted to poor soil.

• Fauna: Limited to smaller herbivores/carnivores due to low nutrient availability.

• Threats: Habitat loss from agriculture, urbanization, and frequent fires.

The Savanna Biome

• Vegetation: Mixed grassland and trees, covering 46% of South Africa.

• Climate: Summer rainfall, with very hot summers and cold winters.

• Soil Composition: Varied; supports different plant types such as Acacia, marula, and baobab.

• Fauna: Supports large herbivores, leading to the presence of substantial carnivores.

• Threats: Human activities causing habitat loss and poaching.

Wetlands

• Definition: Areas with waterlogged soils, crucial for water security and biodiversity.

• Functions:

  • Flood control, water quality improvement, nutrient holding, and wildlife habitat.

• Current Status: 50% of South Africa's wetlands are lost; conservation is essential.

Ecosystem Principles

Ecosystem Definition

• Ecosystem: An area where living organisms interact with each other and the non-living environment.

Ecology

• Study of interactions among organisms and their surroundings.

Key Terminology

• Organism: Individual living entity.

• Population: Group of organisms of the same species in the same area.

• Community: All populations of different species in a habitat.

• Habitat: Specific area where an organism lives.

• Symbiotic Relationships:

  • Mutualism: Both species benefit.

  • Commensalism: One benefits, the other unaffected.

  • Parasitism: One benefits, the other harmed.

Energy Flow in Ecosystems

• Energy travel direction: ONE way through ecosystems from producers to consumers.

• Types of Producers: Autotrophs (e.g., plants) that convert sunlight into energy via photosynthesis.

• Energy Loss: Energy is lost in the form of heat and through metabolic processes.

• Trophic Levels: Sequence in food chains illustrating energy transfer.

Nutrient Cycles Overview

• Matter (atoms) on Earth is cycled; it cannot be created or destroyed.

• Key nutrient cycles:

  1. Water Cycle

  2. Oxygen Cycle

  3. Carbon Cycle

  4. Nitrogen Cycle

• Water cycle: Involves evaporation, condensation, precipitation, and infiltration.

• Oxygen cycle: Involves photosynthesis and respiration.

• Carbon cycle: Involves the movement of carbon through various organisms and the atmosphere.

• Nitrogen cycle: Involves processes that convert nitrogen from atmospheric gas to usable forms for plants, emphasizing nitrogen-fixing bacteria.

Closing Notes

• Understanding these concepts is vital for grasping how ecosystems function and maintain balance.

• Review the nutrient cycles and definitions carefully for the exam.