Abiotic factors, the non-living components of a biosphere, set constraints on the types of organisms that can exist in a given ecosystem. Different types of organisms have adapted to thrive in varying levels of temperature, light, water, and soil attributes. Conditions which are ideal for one organism, however, may be unsupportable for another.
Ambient temperature has a powerful affect on organisms. Some organisms, such as extremophilic bacteria, are specially adapted to live in environments experiencing extremes of heat and cold, and will thus thrive in such environments. Most organisms are mesophiles, growing best in moderate temperatures between 25 Celsius and 40 C. Seasonal changes in temperature often influence the growth patterns and reproduction of organisms. Seasonal temperature variations affect when plants flower, when animals breed, when seeds germinate and when animals hibernate.
Light originating from the sun is essential to all life on earth. Sunlight drives photosynthesis in primary producers, such as cyanobacteria and plants, which rest at the base of the food chain. Many types of plants grow better when they are fully exposed to sunlight, however, some plants are “shade tolerant” and well adapted to growing in low-light conditions. Light affects photosynthetic plants in a number of ways. Red and blue light in the visible wavelength are absorbed by photosynthetic organisms, and while the quality of light does not vary much on land, it can be a limiting factor in the oceans. Light intensity varies with both latitude and seasonality, with hemispherical differences varying among organisms because of the switching of the seasons. Day length can also be a factor, with organisms in northern arctic ecosystems needing to be adapted to extremes of daylight in the summer and darkness in the winter.
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Water is the “universal solvent” for biochemical reactions and also essential to earth’s organisms. Far more species of organisms exist in regions of high humidity compared to arid regions. Some organisms, such as fish, can only exist in a marine environment, and rapidly die when removed from water. Other organisms can survive in some of the driest environments in the world. Plants such as cacti have developed the Crassulacean Acid Metabolism system of photosynthesis, in which they open their stomata at night, when it is much cooler, to take in carbon dioxide, store it as malic acid, and then process it during the day. In this way, they don’t became desiccated and lose water during the high daytime temperatures.
Soil conditions can also have an effect on organisms. For instance, the pH of the soil can have an effect on the types of plants which can grow in it. Plants such as ericas, ferns and protea species grow better in acidic soils. In contrast, lucerne and many species of xerophytes are adapted to alkaline conditions. Other soil attributes which can affect organisms include soil texture, soil air and water content, soil temperature and soil solution (the decaying remains of plants and animals and feces).