An ecosystem is made up of two interacting components: the living or biotic part, consisting of the various groups of organisms; and the physical or abiotic part, which constitutes the environment where the organisms live and develop.
In an ecosystem we find:
- Biotic factors . These are organisms, that is, all living things : from bacteria to thelargest animals and plants . They can be heterotrophic (they obtain their food from other living things) or autotrophic (they generate their food from inorganic substances). They interact with each other through predation , competition , parasitism , commensalism , cooperation, or mutualism . For example: bamboo, caterpillar, flies.
- Abiotic factors . These are all the factors that constitute the physical and chemical characteristics of an ecosystem. These factors are constantly interacting with biotic factors, enabling their survival and growth. For example:water, air, light.
Abiotic factors can be beneficial for some species and not for others. For example, an acidic pH (abiotic factor) is unfavorable for the survival and reproduction of bacteria (biotic factor), but it is for fungi (biotic factor).
In a given ecosystem, biotic factors establish and continually modify the conditions in which organisms can live. Therefore, some organisms develop adaptations to these conditions; that is, living beings can be modified by biotic factors over evolutionary time.
On the other hand, biotic factors also modify abiotic factors. For example, the presence of certain organisms (biotic factors) in the soil can change the acidity (abiotic factors) of the soil.
Examples of abiotic factors
- Water . Water availability is one of the main factors affecting the presence of organisms in an ecosystem, as it is essential for the survival of all life forms. In places where water is not constantly available, organisms have developed adaptations that allow them to spend longer periods of time without contact with water. Furthermore, the presence of water affects air temperature and humidity.
- Infrared light . It is a type of electromagnetic radiation, invisible to the human eye.
- Ultraviolet radiation . This is a type of electromagnetic radiation, which is invisible. The Earth’s surface is protected from most of these rays by the atmosphere. However, UV-A rays (wavelengths between 380 and 315 nm) reach the surface. These rays penetrate the inner layers of the skin, damaging the connective tissue beneath the epidermis, which causes premature aging (which results in wrinkles). In contrast, UV-B rays (wavelengths between 315 and 280 nm) tan the skin and cause sunburn. Both types of UV rays can cause permanent damage to the DNA of skin cells and produce mutations that lead to skin cancer.
- Atmosphere . The atmosphere and its characteristics affect the development of organisms.
- Temperature . For all organisms, there is a maximum and minimum ambient temperature at which they can survive. Therefore, global temperature changes result in the extinction of various species. Microorganisms ( called extremophiles) can tolerate extreme temperatures.
- Air . Air content affects the development and health of organisms. For example, carbon monoxide in the air is harmful to humans. Wind also affects plant growth, for example: trees that live in areas with frequent winds from the same direction grow crooked.
- Visible light . It is essential for plant life as it is involved in the process of photosynthesis. It allows animals to see their surroundings to perform various activities, such as foraging for food or protecting themselves.
- Calcium . It is an element found in the Earth’s crust but also in seawater . It is an important element for biotic factors: it enables the normal development of leaves, roots, and fruits in plants, and in animals, it is essential for strong bones , among other functions.
- Copper . It is one of the few metals found in nature in its pure state . It is absorbed as a cation . In plants, it participates in the process of photosynthesis. In animals, it is found in red blood cells and participates in the maintenance of blood vessels, nerves, the immune system, and bones.
- Nitrogen . It makes up 78% of the air. Legumes form symbioses in their roots with bacteria that absorb it directly from the air. The bacteria convert it into nitrate. Nitrate is used by various organisms to synthesize proteins .
- Oxygen . It is the most abundant chemical element by mass in the biosphere, that is, the sea, air, and soil. It is an abiotic factor but is released by a biotic factor: plants and algae, thanks to the process of photosynthesis. Aerobic organisms are those that require oxygen to convert nutrients into energy. Humans, for example, are aerobic organisms.
- Altitude . Geographically, the altitude of a location is measured by its vertical distance from sea level. Therefore, when indicating altitude, it is indicated, for example, as 200 meters above sea level. Altitude affects both temperature (it decreases by 0.65 degrees for every 100 meters of altitude) and atmospheric pressure.
