7.4.5 Ecosystems

Key Components of Ecosystems

1. Biotic Factors: The living elements of an ecosystem, which include:

• Predators: Affect prey population sizes.
• Competition: Between organisms for resources like food, mates, or space.
• Disease: Can reduce populations and influence natural selection.

2. Abiotic Factors: The non-living elements of an ecosystem, such as:

• Light intensity: Influences photosynthesis rates and plant growth.
• Temperature: Affects enzyme activity and the metabolic rate of organisms.
• Water availability: Determines species survival, especially in arid environments.
• Soil pH and nutrient content: Essential for plant growth and species distribution.

Niche

• A species' niche is its specific role within the ecosystem.
• This includes its:
  • Biotic interactions: How it interacts with other organisms (e.g., predation, competition).
  • Abiotic interactions: How it utilises non-living resources (e.g., light, nutrients).
• No two species can occupy the same niche indefinitely due to competitive exclusion—one will outcompete the other.

Distribution and Abundance

• Distribution: Where species are found within the ecosystem.
  • Affected by both biotic and abiotic factors (e.g., light availability, predator presence).
• Abundance: The number of individuals of a species in an ecosystem.
  • Influenced by resource availability, competition, and environmental conditions.