BIOTIC FACTORS: CLASSIFICATION AND EXAMPLES - ENVIRONMENT - 2025

The biotic or abiotic elements are components of a living ecosystem interacting components and nonliving (abiotic). This includes animals, plants, ferns, liverworts, fungi, lichens, algae, bacteria and archaea, constituting the community or biocenosis.

Biotic factors are classified in classic terms in fauna and flora, although today the biological classification considers many more categories. To adapt to current knowledge of biological diversity, six categories must be taken into account (animals, plants, fungi, protists, bacteria and archaea).

Biotic factors of an ecosystem. Source: mendel

Biotic factors by definition are an inseparable part of every ecosystem, so they are found in all ecosystems on the planet. They can be terrestrial or aquatic, marine or freshwater, found hundreds of kilometers below the earth's surface or in the atmosphere.

Classification of biotic factors

Plants and animals. Source: commons.wikimedia.org

In classical terms, biotic factors are classified as flora and fauna, excluding human beings from the biotic component and treating them as a human factor. However, for the sake of accuracy and consistency with modern biological systems the classification should be considered more extensive.

This taking into account that the biotic environment is no longer classified into just two groups, reaching up to six different kingdoms. On the other hand, from the ecological perspective, excluding the human being implies perspective problems to understand the dynamics of ecosystems.

- Classic classification

The classic classification considers the fauna, divided in turn into different ways according to the approach with which the study of the ecosystem is approached. Likewise, the flora present in the analyzed natural space is delimited, generally encompassing spermatophyte plants, ferns, mosses, fungi and lichens.

Fauna

Fauna includes all the components traditionally assigned to the animal kingdom, which can be separated into autochthonous or native fauna and exotic or introduced fauna. Within each category, the biological or taxonomic classification is used to delimit the different groups present.

Flora

Generally, the classic concept of the plant kingdom is used to define the flora component of the ecosystem. Included in this category are both angiosperms and gymnosperms, as well as ferns, mosses, liverworts, fungi, lichens and algae.

In the same way, it is convenient to differentiate between those organisms typical of the ecosystem and those alien or introduced.

- Contemporary biological classification

The currently generally accepted classification of the living world considers three domains and six kingdoms. The domains are the Bacteria, Arquea and Eukarya. The first two include a single kingdom each (Bacteria and Archea respectively) and Eukarya includes three kingdoms (Animal, Vegetable and Protista).

The human being

Our species is obviously included in the animal kingdom, however from the methodological point of view it is convenient to give it relevance in the analysis. This considering the profound impact that their actions cause on ecosystems worldwide.

Examples of biotic factors

In almost any area of ​​the planet we will find biotic factors, from extreme conditions such as geysers and deep sea, to the human digestive system.

Biotic factors in terrestrial ecosystems

Terrestrial ecosystems vary from the tropical forest to those present in the Sahara desert. In most cases, biotic factors include elements from all six known kingdoms.

In general, plants are the determining structural element and animals the second most obvious factor. A more in-depth study of ecosystems reveals the presence of elements from other kingdoms that perform important functions such as saprophytes, decomposers and symbionts.

The tropical rain forest

Biotic factors in a rainforest like the Amazon include organisms from all known kingdoms in an intricate web of relationships. From the large trees, through the varied fauna, to the fungi and bacteria in the soil and lichens in the bark.

Biotic factors in aquatic ecosystems

In both marine and freshwater ecosystems there is a great diversity of biotic factors. From the base plankton of most food chains and archaea in the deep sea, to large marine mammals.

Coral reefs

Coral reef. Source: I, Kzrulzuall

Some marine ecosystems are rich in biotic factors, such as coral reefs. In these inhabit diverse species of fish (bone and cartilaginous), mollusks, crustaceans, algae, bacteria and other organisms.

Biotic factors in the human domain

The human habitat, in terms of the city and the home itself, constitutes a set of ecosystems where biotic factors proliferate. The diversity of species that can be counted in an average home, especially in tropical areas, is enormous.

Thus, the plants of the garden can be mentioned, going through the diverse microscopic species of bacteria and fungi and diversity of insects and arachnids.

The human body

The interior of the human body is itself an ecosystem inhabited by various species of bacteria, archaea and protists. They are found mainly in the digestive system, but also on the skin and elsewhere.

Some serve beneficial functions in digestion, while others are disease-causing pathogens.

Biotic components of an ecosystem

To explore the variety of biotic components that can exist in an ecosystem we will rely on the current biological classification.

Bacteria

Bacteria Kingdom. Source: NIAID

They are prokaryotic microorganisms (0.5 and 5 μm in length), unicellular without a highly specialized internal cellular organization. These beings are the most abundant component in ecosystems, being found in almost any area of ​​the planet.

They inhabit both terrestrial and aquatic ecosystems, from several kilometers below the earth's surface to several kilometers in the atmosphere. Their populations are counted by millions of individuals and they also inhabit the interior of the human body.

They fulfill important functions in ecosystems both in the organic decomposition process and in various biogeochemical cycles. There are species that cause diseases and others are beneficial for health, for example fulfilling functions in the digestive system.

Arches

Archea Kingdom. Source: NASA

These organisms were originally classified as bacteria, but today they are considered a different kingdom due to their biochemical and molecular distinctions. They are prokaryotic organisms that inhabit many spaces on the planet, including very extreme environments.

For example, they are found in hot springs, in fumaroles on the seabed, in extremely salty waters, and in the human colon.

Protists

Protist kingdom. Source: Prof. Gordon T. Taylor, Stony Brook University

This is a category that includes all eukaryotes (organism with nucleated cells and organelles) that cannot be classified in the other kingdoms and therefore is a poorly defined group.

It includes both unicellular and multicellular organisms that inhabit diverse ecosystems and are dependent on humidity. Therefore, they live in aquatic ecosystems or in environments with availability of humidity in the environment.

They are especially abundant in plankton, at the bottom of aquatic ecosystems, and in the soil. These include red algae, brown algae, diatoms, dinoflagellates, amoebas, slime molds, and others.

Plankton

Plankton plays a fundamental role in marine ecosystems as it is the basis of the main food chains. On the other hand, phytoplankton is the main source of oxygen for the Earth's atmosphere.

Mushrooms

They are heterotrophic unicellular or multicellular eukaryotic organisms with a chitin cell wall that play an important role as decomposers. They include mushrooms, molds and yeasts and their habitats are diverse.

Various species of fungi form associations with mosses and bacteria, constituting lichens. Others have symbiotic relationships with plant roots, constituting mycorrhizal fungi, which contribute to the nutrition of these organisms.

Plants

It includes angiosperms, gymnosperms, ferns, liverworts and mosses, characterized by being multicellular eukaryotic organisms with a cell wall made of cellulose. In some ecosystems they are the most evident element, especially in terrestrial ones such as jungles, forests, bushes and grasslands.

Jungles and forests

The jungles and forests are ecosystems with a predominance of the tree component that occupy large areas of land. The plants in these ecosystems provide shelter and food for the other components of the ecosystem.

On the other hand, thanks to the plant mass, these ecosystems play a very important role in the water cycle and the provision of fresh water.

Grasslands

Savannas, grasslands, steppes, and pampas are biomes that occupy much of the earth's surface and are home to large populations of herbivorous animals.

Animals

The animal component of ecosystems is possibly the most striking for humans. This includes an extensive set of multicellular eukaryotic organisms without a cell wall that inhabit diverse ecosystems.

They are found from large mammals to numerous species of insects and the components of this kingdom occupy the intermediate and upper positions of the food chains.

The human factor

The Homo sapiens species is the most influential biotic factor in ecosystems due to its ability to alter them. Human activity is a source of drastic alterations to the landscape and pollution of ecosystems.

References

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