ABIOTIC

FACTORS

What non-living factors influence the distribution of organisms in a habitat?

LIGHT INTENSITY

Producers (plants) require light for photosynthesis If low light levels of light are available in a certain

habitat, plant populations which survive these conditions will thrive.

Light can be absorbed at different wavelengths, reflecting back unused wavelengths as colour. This can affect the quality of sunlight for aquatic ecosystems, where blue and red light is absorbed, but it cannot penetrate deep water.

Some producers flower at a certain time during the year, and the duration of the dark period is crucial to flowering. There are short-day plants, and long-day plants. Therefore, a habitat that has more than 12 hours exposure to sunlight, will have a thriving population of long day plants.

OXYGEN AVAILABILITY

Dependent on the supply within water and soil (edaphic) If the water is cold/fast flowing/ -> sufficient amount of

oxygen If the water is hot/still/stagnant -> oxygen content will drop Soil is well aerated – spaces between soil particles contain

air -> oxygen available for respiration of plant roots If waterlogged -> spaces are filled with water, so the roots

are deprived of oxygen

WATER AVAILABILITY

Water availability is Influenced by:o Precipitationo Rate of evaporationo Rate of loss by drainage through the soil (edaphic)

All living organisms require water; therefore a limited supply of it can affect the ecosystem.

Lack of water could lead to death from dehydration (unless they are adapted to dry conditions e.g Camel & Cactus)

Some animals have sweat glands – used as a cooling device Insects absorb water directly from the atmosphere

TEMPERATURE

In every organism, there is an optimum range of temperatures that allow growth and reproduction.

The extremes of temperature determine where an organism’s habitat may be.

This can affect enzyme-controlled reactions within plants and exothermic animals.

Endotherms must be able to live in temperatures which are not too high or low, so they can control their core body temperatures.

Cold-blooded animals need to survive in a climate, in which their body can adapt to.

Some animals hibernate when the temperature drops to a low level (in Winter)

WIND AND WATER CURRENTS

Wind increases water and heat loss from the body -> environmental stress

Strong winds -> fewer species can survive Strong water currents, leads to more environmental

stress, because of the strong force, which would require organisms that are strong swimmers.

Wind dispersal – aids dispersal of pollen grains of some plants and dispersal of insects.

EDAPHIC FACTORS (SOIL)

Sand –> loose shifting, little to grow in it, contain very few nutrients for plant growth -> plants with an extensive root network, are adapted to physiological drought conditions

Loam -> particles of a large range of sizes less prone to leaching (minerals escaping rapidly through water loss)

pH – affects the mineral availability and influences growth and development of the plants.