Abiotic factors refer to non-living physical and chemical elements in the ecosystem that affect living organisms in terms of growth, maintenance, reproduction and distribution. They’re at times called abiotic components. Abiotic factors can be classified into five main types namely: climatic factors, topographical factors, edaphic factors, air and chemical elements. All these factors are discussed below in detail.
Climatic Factors
These are atmospheric conditions such as precipitation, temperature, sunlight, wind and humidity.
Precipitation is all the forms of water such as rain, snow, sleet, fog, mist, and hail that fall to the earth’s surface or remains suspended in the atmosphere. It is responsible for depositing most of the fresh water on the planet. Water is used mainly for photosynthesis, transport of nutrients, mechanical support, various enzyme driven metabolic activities in the cells and for cooling. There is an abundance of flora and fauna in areas with high precipitation. Such areas are dominated by large, broad leaved vegetation and large organisms such as elephants. Some organisms are adapted to dry conditions while others thrive in wet areas.
Temperature is the degree of hotness or coldness of a substance. The optimal day and night temperature range for plant and animal growth and maximum yields varies among plant and animal species. Homoiothermic animals can tolerate wider temperature ranges than poikilothermic animals. in a similar vein, temperate forest are found in colder regions while xerophytes are adopted to hot climatic conditions. Enzyme activity and the rate of most chemical reactions generally increase with rise in temperature. Excessively high temperatures lead to denaturation of enzymes and other proteins while excessively low temperatures can also cause limiting effects on plant growth and development. Seasonal temperature changes often bring about certain behavioral responses such as hibernation and migration in certain types of animals.
Sunlight is a portion of the solar radiation that is visible at Earth’s surface. Light affects living things in terms of intensity, quality and duration. Light is essential in the production of chlorophyll and in photosynthesis, the process by which plants manufacture food that sustains almost all forms of life. The rate of photosynthesis increases as the intensity of sunlight increases. Sunlight enhances or inhibits plant processes such as: stomatal movement, phototropism, translocation, abscission and mineral absorption. Submerged aquatic plants grow at depths to where light penetrates. Light affects different aspects of an animal’s life such as growth, pigmentation, migration and reproduction. Ultraviolet rays are known to cause mutations in the DNA of various organisms. Different animals have evolved different morphological, physiological, behavioral and ecological adaptations during the course of their evolution to varying photoperiods.
Wind is simply defined as air movement. Wind tends to increase the rate of transpiration in plants. When transpiration rate exceeds that of water absorption, partial or complete closure of the stomata may occur which will lead to a decrease in the rate of photosynthesis, growth and yield. Exposure to strong can drastically alter the direction of growth and he shape of plants. Wind serves as an agent of pollen transfer from one flower to another thus aiding in the process of pollination. Wind carries scent which determines the positioning of hunting animals with respect to their prey in a habitat.
Humidity is the amount of water vapor in the atmosphere. Relative humidity affects the opening and closing of the stomata which regulates loss of water from the plant through transpiration as well as photosynthesis. This generally determines the type of plants and animals that can survive in a given area. Xerophytes survive in dry areas with low humidity while mesophytes are adapted to moderately humid regions. Amphibians cannot survive in hot and dry habitats. Mammals such as camels are well adapted to the dry desert environment.
Topographic Factors
Topographic factors or physiographic factors refer to the shape and physical features of earth’s surface like: aspect, altitude and slope.
Altitude is the vertical elevation of a particular area from the sea level. Dominance of certain plant and animal types varies with altitude. There’s little or no plant and animal life on high mountain tops because there are extremely low temperatures. Altitude tends to produce contrasting local climates. As we ascend towards a higher altitude, the wind velocity becomes high, atmospheric pressure and oxygen decreases; the air and soil temperature tends to get lower and the relative humidity becomes higher. Low atmospheric pressure can lead to “altitude sickness”, which is caused by oxygen starvation in the tissues. The seasonality of ripening of various fruit crops, such as durian , is modified when they are planted in different altitudes. Growth in plant height diminishes regularly and noticeably with the increase of altitude. Most of the mossy forests are found at elevation above 1520 meters and not in the lowlands. Cloud rats are found in high mountains unlike the lowland field rats.
Aspect is the direction in which a slope faces in relation to the sun. In the northern and southern hemispheres, slopes facing the sun are warmer than those facing away. This facilitates the process of photosynthesis and transpiration. Mountain slopes which are oriented facing the sun generally have thicker plant growth than those on the shaded side.
Slope. Plants which need large amount of water are found in lowlands or along gentle slopes while plants which can tolerate little moisture grow along steep slopes.
Edaphic Factors
Edaphic factors refer to the physical, chemical, and biological properties of soil that result from biological and geological phenomena. Variation in the physical, chemical, and biological properties of the soil has distinct effects on plant growth and development. Soil pH and cation exchange capacity dictates the availability of certain essential elements to plants. On the other hand, soil properties such as soil texture and soil structure affect the capacity of the soil to retain and supply water to the plant. Soil air is essential for respiration of soil organisms.
Air
Air is the biggest essential factor without which life itself would not exist. Oxygen is essential in respiration for the production of energy that is utilized in various growth and development processes. The amount of dissolved oxygen usually determines the number and types of organisms living in that body of water. Carbon dioxide is a raw material in photosynthesis. Nitrogen is essential to plants for protein synthesis.
Chemical Elements
Carbon and nitrogen are a major component in proteins. Proteins do make up the structural components of most organs and tissues, including muscle, enzymes and neurons. Magnesium plays a crucial role in the biochemical reactions occurring in the body. Magnesium as an enzyme co-factor plays an important role in the breakage of glucose and fat molecules, in the production of enzymes, proteins and regulation of cholesterol. It is also responsible for the stability and proper functioning of DNA. Iron is necessary for photosynthesis and is present as an enzyme cofactor in plants. Phosphorus is needed for the conversion of light energy to chemical energy (ATP) during photosynthesis.