Abiotic components

The way in which plants and animals grow and carry out their different activities is a result of several abiotic factors. These factors are light, temperature, water, atmospheric gases, wind as well as soil (edaphic) and physiographic (nature of land surface) factors.

Light | Temperature | Water| Atmospheric gases | Wind | Soil | Physiographic Factors|

Light

Light energy (sunlight) is the primary source of energy in nearly all ecosystems. It is the energy that is used by green plants (which contain chlorophyll) during the process of photosynthesis; a process during which plants manufacture organic substances by combining inorganic substances. Visible light is of the greatest importance to plants because it is necessary for photosynthesis. Factors such as quality of light, intensity of light and the length of the light period (day length) play an important part in an ecosystem.

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The Maize plant is not influenced
by night length.

The following definitions are also important:

Light requirements of plants differ and as a result distinct layers, or stratification, can be observed in an ecosystem. Plants which grow well in bright sunlight are called heliophytes (Greek helios, sun) and plants which grow well in shady conditions are known as sciophytes (Greek skia, shade ).


Temperature

The distribution of plants and animals is greatly influenced by extremes in temperature for instance the warm season. The occurrence or non-occurrence of frost is a particularly important determinant of plant distribution since many plants cannot prevent their tissues from freezing or survive the freezing and thawing processes. The following are examples of temperature effects with ecosystems:


Water

Plant and animal habitats vary from entirely aquatic environments to very dry deserts. Water is essential for life and all organisms depend on it to survive in especially desert areas.

The Water Cycle in Nature


Atmospheric gases.

The most important gases used by plants and animals are oxygen, carbon dioxide and nitrogen.


Wind

Winds or air currents arise on a world-wide scale as a result of a complex interaction between hot air expanding and rising (convection) in the mid latitudes. This has various effects on the rotation of the earth and results in a centrifugal force which tends to lift the air at the equator. This force is known as the Coriolis force and tends to deflect winds to their left of the southern hemisphere and to the right in the northern hemisphere. Winds carry water vapour which may condense and fall in the form of rain, snow or hail. Wind plays a role in pollination and seed dispersal of some plants, as well as the dispersal of some animals, such as insects. Wind erosion can remove and redistribute topsoil, especially where vegetation has been reduced. Warm bergwinds results in desiccation which creates a fire hazard. If plants are exposed to strong prevailing winds are they usually smaller than those in less windy conditions.


Soil (edaphic factors)

These factors include soil texture, soil air, soil temperature, soil water, soil solution and pH, together with soil organisms and decaying matter.

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The main Soil Factors


Physiographic factors

These factors are those associated with the physical nature of the area, such as altitude, slope of land and the position of the area in relation to the sun or rain-bearing winds. Altitude plays a role in vegetations zones. Slopes are important when considering the temperature of the soil surface on land with a northern slope, on level and on land with south facing slopes. In South Africa the south-eastern slopes face the rain-bearing winds and in some areas are covered with forest, whilst the slopes on the leeward side are in a rain-shadow and thorn scrub is often found growing on these slopes. A very good example of this is the South Eastern Wind blowing in Cape Town.


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