Discuss the abiotic factors in distribution of living organisms

1. Climatic factors
Climate is the single most important factor that plays an overriding role in the distribution of organisms. The climatic factors can further be grouped into: light, temperature, moisture wind/atmospheric conditions and humidity. Solar energy is the driving force behind photosynthesis. Climate leads to temporal variations through its seasonality. Temperature and moisture are the two main limiting factors of life on earth. Potential evapotranspiration, water surplus and deficit delimit the distribution patterns of vegetation types.

2. Topographic Factors
As indicated earlier, topographical differences can affect distribution by acting as barriers. Mountain terrains, for instance, can limit the spread of animals and plants by separating potential habitats or by the provision of unfavourable climates and substrate. In East Africa, mountain tops impose a selection effect on distribution by low mean temperature. The current limited distribution of the equatorial rainforest can be explained by altering rainfall conditions through aspect. The south east slopes of Mt Kenya and Mt Kilimanjaro carry abundant life because of high moisture. The drier northward and westward slopes are characterized by scant life. The effects of aspect and light conditions and hence substrate conditions are distinct.

3. Edaphic factors
Soils are important in determining the pattern and distribution of living organism; they provide the anchor for plants and are the nutrient store upon which plant life is dependent. Soil contains both abiotic and biotic components and provides the vital link between living and non-living phenomena, without which terrestrial ecosystems would not operate. Soils are made of the mineral components and vary in type. The soil texture is the proportion of silt, sand, clay and this determines the degree to which roots penetrate the soil, the water content, and aeration and soil temperature. Sand for example has large pore spaces. This decreases the capillary so that sandy soils cannot hold water. Clay soils have small pore spaces, thus water is easily held. The thin layer found around each soil particle is referred to as hygroscopic water or water of adhesion. This water is bound to the soil particles, and is unavailable to plants. Bound to the water
of adhesion is another body of water known as water of cohesion or capillary water. It is the propensity of water to adhere to the surface and get pulled up. The water is loosely held to the soil particles on the water of adhesion. At saturation a soil is wetted and all gravitational water is drained out.
Soil is also the habitat of different fauna. The occurrence of certain plant species depends upon soil conditions. The distribution of cosmopolitan plants depends upon distributed substrate. The occurrence of a plant species in any substrate depends upon its occurrence and ability to grow and successfully compete for opportunities the soil offers. Variations in patterns of distribution can be said to be a response to soil
conditions. Soils vary in nutrients and water conditions, grain size and arrangement, and in depth. There is no soil type with uniform conditions. Water logged sites attract grasses while well-drained sites favour the dominance of tall plants. Frequent nutrient shortages in the soil initiate competition among organisms that may lead to the extinction of less aggressive species. Certain distributions can be explained on the basis
of soil PH, defined as the level of acidity or alkalinity. Acid soils support oxylophytes while halophytes occur in saline soils.

4. Geological Factors
Besides the climatic history of an organism’s habitat, distribution can also be determined by geological factors. Environmental mode is far from having ways been identical or normal. Most of the processes such as volcanism and mountain building have bursts or peaks that lead to massive killing and extinction of organisms and species. The eruption of volcanoes and the burning from underneath of organisms in East Africa’s Rift Valley are such examples.
However, some geological changes have been gradual and “accommodating”. The effect of geological history in the distribution of organisms was recognized. It is associated with the origin of Vireroin Biogeography.
Wegner’s theory of plate tectonics provided ample evidence for the distribution of similar animals and plants on different continents. His theory supported by that of palaeomagnetism and sea-floor spreading, emphasizes that certain distributions have been passive. The involved organizations have merely been transported across the globe due to constant drifts, which have split the once continuous continents apart and led to new patterns.
Geological processes caused many variations in landforms and subsequent patterns of distribution of plants and animals. The diversity of landforms in East Africa is reflected in its varied climates, which have led to normal diversity in vegetation. The geological processes have caused variations in land and sea sizes leading to differences in habitats for terrestrial and aquatic organisms. The effects of these processes are always confused with those of extra-terrestrial forces such as meteoric impact that led to the disappearance of certain distributions. This period saw the Mesozoic extinction (65million years B.P) in which certain mammals like reptiles were eliminated. The asteroid impact hypothesis of the Pleistocene ice age and the killing of large mammals is another geological episode whose effects can be seen today. From these and other
evidences, it appears that the biosphere has not always evolved gradually, but in bursts.

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francis1897 answered the question on October 11, 2022 at 05:41