How do biotic and abiotic components of biomes interact?

Introduction: Biotic vs Abiotic

Every biome on Earth is made up of two key parts:

• Biotic components are the living things – plants (flora), animals (fauna), fungi, and microorganisms like bacteria. These organisms interact with each other through food chains, competition, and mutual support.
• Abiotic components are the non-living parts – such as climate (temperature and rainfall), rocks, soils, water, and the atmosphere. These factors create the physical environment in which living things survive.

The health of a biome depends on the interactions between the living and non-living parts. For example, plants rely on soil nutrients and water to grow, while animals rely on plants for food and shelter. At the same time, plants and animals change the abiotic environment through processes such as weathering, nutrient cycling, and transpiration.

When biotic and abiotic parts are in equilibrium (balance), ecosystems can function effectively. If one part changes, the effects can spread throughout the whole system.

Key Interactions Between Biotic and Abiotic Components

1. Weathering and Soil Formation

• Biophysical weathering: Plant roots grow into cracks in rocks, forcing them apart.
• Biochemical weathering: Plants and animals release acids during decay or digestion that dissolve rocks.
• These processes release minerals into the soil, enriching it with nutrients that plants need to grow.

Example: Seabirds deposit guano (rich in nitrogen and phosphorus), which can dissolve rock and fertilise soils.

2. Photosynthesis and Respiration

• Plants absorb sunlight, carbon dioxide, and water to produce glucose and oxygen through a process known as photosynthesis.
• Animals (and plants at night) respire, using oxygen and releasing carbon dioxide back into the atmosphere.
• This exchange maintains a balance of gases in the atmosphere and supports the carbon cycle.

Example: In tropical rainforests, dense vegetation absorbs vast amounts of carbon dioxide, helping regulate the Earth’s climate.

3. Nutrient Cycling

• Nutrients move between three main stores:
  • Biomass (living plants and animals)
  • Litter (dead material on the ground, such as leaves)
  • Soil (nutrient-rich layer that supports plant growth)
• When plants and animals die, decomposers break them down, returning nutrients to the soil.
• Plants absorb these nutrients to grow, and the cycle continues.

Example: In rainforests, hot and wet conditions cause rapid decomposition, meaning nutrients are quickly recycled. In deserts, decomposition is slow due to the limited availability of moisture.

4. Hydrological Cycle Regulation

• Plants intercept rainfall, reducing surface runoff and helping water infiltrate the soil.
• Through transpiration, plants release water vapour into the atmosphere, which can condense and fall as rainfall.
• Different plant adaptations influence how water is stored and cycled.

Example: In rainforests, transpiration from dense vegetation adds vast amounts of moisture to the atmosphere, helping drive heavy rainfall. In deserts, succulent plants such as cacti store water to survive long dry periods.

Case Study Comparisons

• Tropical rainforest: High rainfall and heat → rapid decomposition → thin but nutrient-rich soils (when vegetation is intact).
• Desert: Limited rainfall → slow weathering and decomposition → nutrients mainly stored in soil, but little vegetation to use them.
• Temperate grasslands: Deep fertile soils build up as grasses die and decay each year, supporting large grazing animals.

Why These Interactions Matter

• They maintain the nutrient, carbon and water cycles, essential for life.
• Disruption (e.g., deforestation, climate change, overgrazing) can damage soils, reduce biodiversity, and destabilise global systems.