7.4.2 Abiotic & Biotic Factors

Biotic Factors

Biotic factors are the living components of an ecosystem that influence populations and communities. Examples include:

• Food availability: Abundance or scarcity of food resources affects population size.
• Pathogens: The presence of disease-causing organisms can reduce population numbers.
• Predators: Predator-prey interactions influence population dynamics.
• Competition: Intraspecific (within species) and interspecific (between species) competition affects survival and reproduction.

Abiotic Factors

Abiotic factors are the non-living aspects of an ecosystem that affect the organisms living there. Examples include:

1. Temperature:

• Each species has an optimum temperature for survival.
• Temperatures above or below this can reduce survival rates or affect metabolic processes.

2. Light Intensity:

• Light is crucial for photosynthesis in plants.
• Higher light intensity often leads to increased productivity and larger populations of plants and herbivores.

3. pH:

• Affects enzyme activity as each enzyme works best at its optimum pH.
• Extreme pH levels can reduce the number of species in an area.

4. Water Availability:

• Scarce water supply limits population size to only species adapted to dry conditions.

5. Humidity:

• High humidity reduces transpiration rates in plants, favouring growth in moist environments.
• Conversely, low humidity supports only species adapted to dry environments.

Interactions Between Abiotic and Biotic Factors

• Abiotic factors can directly influence biotic factors. For example, temperature affects the activity of predators and prey.
• A balance of both biotic and abiotic factors ensures ecosystem stability.