Abiotic Factors (7.1.2)

= non-living factors.

Abiotic factors that can affect a community:

Light intensity (animals + plants)

Temperature (animals + plants)

affects the rate of photosynthesis
both animals and plants have evolved to grow healthily at their optimum temperatures

Availability of water/Moisture levels

plants and animals need water to survive
many plants cannot survive in waterlogged soils - their roots are unable to respire. Other plants (e.g. pitcher plants) grow best in bogs where the moisture levels are high.

Soil pH and mineral content

soil pH affects the rate of decay and therefore how fast mineral ions return to soil (which are then taken up by other plants)
many plants require high levels of soil mineral to grow well. Carnivorous plants (e.g. pitcher plants) have evolved to catch insects to supplement the low levels of mineral in their soil
different species of plants thrive in different nutrient concentration levels
some plants (azaleas) grow best in acidic soil, some (clematis) prefer alkaline, some (hydrangea) can grow in both
- the flower colour of plants like hydrangea changes in different soils

Wind intensity and direction

has a huge impact on where organisms are found within an ecosystem - many organisms prefer sheltered locations
- plant seeds are more likely to settle and germinate there, and animals which depend upon these are more likely to live close to where they grow
the strength of the wind can also affect the growth of individual organisms
affects the rate of transpiration (movement of water from root to leaves) in plants
- transpiration affects the temperature of the plant and the rate of photosynthesis because it transports water and mineral ions to the leaves

Carbon dioxide (plants)

affects the rate of photosynthesis in plants - CO₂ is a reactant in photosynthesis
also affects the distribution of organisms as some thrive in high CO₂ environments
woodlands often have higher CO₂ levels than open grassland, so many plants living in open areas have evolved mechanisms to overcome a shortage of CO₂
areas with higher levels of CO₂ are more likely to have healthy plants growing
- farmers often release CO₂ within their greenhouses to maximise crop yield

Oxygen levels (aquatic animals)

levels in water vary greatly, unlike in the air
most fish need a high concentration of oxygen to survive
healthy lakes and rivers have high levels of oxygen, whereas polluted waters have low levels, meaning only certain species can survive (e.g. sludgeworms)

	Created by Vanessa Andrews almost 5 years ago

Biology Note on Topic 7: Ecology.