Biocenosis: what it is, components and characteristics

An ecosystem is a biological system made up of living and inert elements that are interrelated in a series of chains and complex interactions. Thus, a specific ecosystem encompasses the biodiversity that inhabits and interacts in a physical space, with characteristic chemical and environmental properties. In the world, there are a total of 8 different types of ecosystems.

Despite this general definition, conceiving an ecosystem as a closed and delimited space is a mistake. Each ecosystem is made up of practically infinite micro-ecosystems, with specialized characteristics and environments. Without going any further, the bark of a tree could be considered a microecosystem, since the conditions have nothing to do with it. of light, humidity and availability of resources in this small space with the surface of the trunk or branches, for example.

Something as simple as the footprint of a large mammal can form a microecosystem for bacteria and small arthropods. Thus, the word "ecosystem" serves us to broadly compartmentalize the variety of environments in the world, but not the real biological needs of the different species of beings alive. To go deeper into this term and its implications, today

We will tell you everything about the biocenosis, or what is the same, the living part of the ecosystem.

• Related article: "The 8 types of biomes that exist in the world"

What is biocenosis?

The biocenosis (or biological community) is known as the set of living beings that coexist, develop and interact in the same place. In other words, this term encompasses all biological populations that coexist in space and time. This slightly abstract concept is essential when it comes to understanding the general functioning of the ecosystem, because you must take into account the following:

Biotope (geographic space) + biocenosis (living beings) = ecosystem

Thus, the biotope refers to a physical space with specific physicochemical characteristics (temperature, light, humidity, pH and others) and the biocenosis, to the living beings that inhabit it.

Generally, when talking about a biological community, the first thing that comes to mind is large mammals and birds, striking for their size and for their ease of observation. Nothing could be further from reality, well we can distinguish biocenosis into 3 large categories:

• Zoocenosis: refers to all animals in the ecosystem, from the most basic invertebrate to the largest super predator.
• Phytocoenosis: the variety of plants.
• Microbiocenosis: referring to microorganisms, that is, protozoa, bacteria, microscopic fungi and other living beings that are not directly observable.

Below, we present a series of interesting data from a zoological point of view about the different strata that make up the biocenosis. Go for it.

1. zoocenosis

Perhaps it sounds to you that at this level there is a concrete and easily explorable relationship: the trophic pyramid. Living beings base their existence on 3 events: surviving, eating and reproducing..

To carry out the second task, the animals "organize" (the quotation marks are necessary, since it is not a conscious behavior) to the time to eat and prey, with the result that the biocoenosis (and therefore the ecosystem) remains stable over time, at least ideally.

The trophic pyramid is conceived as a series of links, where the base is represented by plants (producers) and the following spaces by herbivores, carnivores and top predators (the “beak”), which feed on other hunting animals. This compartmentalization is quite basic and general, since in it many important feeding strategies, such as detritivorous living beings, parasites, hematophagous, necrophagous and many more.

So that, animals continually interact with each other to eat, avoid being eaten, compete for resources and, exceptionally, help each other. The ecological niche represents this continuous "tug of war" between animals, because when two species overlap in terms of habits, exploitation of resources and spatial occupation is concerned, one of the two is doomed to the extinction or expulsion of said niche.

• You may be interested in: "The 6 types of ecosystems: the different habitats we find on Earth"

2. phytocoenosis

If we talk about phytocenosis, we cannot leave the term biomass in the dark. Biomass is defined as the weight of living material found in a given area and time.. This parameter can be expressed in normal or dry weight, generally with measurements of the g/m2 and kg/m2 type. Although the strict concept should cover animals and microorganisms, one of the most important indicators of the productivity of an ecosystem is the biomass represented by the phytocenosis, that is, the living beings vegetables.

To understand biomass, it is necessary to know in general the net primary production, the rate at which new biomass is generated in an ecosystem, generally in the form of photosynthesis. For example, a swamp has a productive capacity of 2,500 gC/m2/year, while the value in a desert is negligible, 3 gC/m2/year.

This is widely related to the previously described concept of trophic chain, since It is estimated that from one level to another there is a loss of 90% of the energy provided by the biomass consumed. Thus, from a primary producer (plant) to a top predator, which is 4 levels up, a total change of 1,000 g/m2 to 1 g/m2 of transferable biomass can be produced.

3. Microbiocenosis

We do not forget about the microbiocenosis, those living beings that cannot be perceived at first sight, but that does not mean that they are of great importance to ecosystems. Without going any further, there are approximately 50 million bacterial cells in a gram of soil and one million bacterial cells in a milliliter of fresh water. With these data, it can be calculated that 15% of the total biomass of the planet corresponds to microscopic beings, or what is the same, about 70 gigatonnes by weight.

We can say little more about microbiocenosis without going into complex terms, apart from the fact that we also present it, strange as it may sound. The microbiome that settles in our mucous membranes and intestines, for example, is a type of microbiocenosis Composed of bacteria, generally symbionts and commensals.

• You may be interested in: "The 3 types of bacteria (characteristics and morphology)"

The biocoenosis is not stagnant

The fact that a set of biological communities exist in the same space and time in a community does not mean that they will do so in the future. The biotope changes and, therefore, living beings must get used to new challenges resulting from environmental variations (physical or chemical).

Communities can undergo variations over time, something known as succession. These tend to happen at very slow scales, and thanks to them, changes in populations occur, that is, modifications in the biocenosis of the ecosystem itself.

In addition to all this, there are external factors that limit the biological distribution of a species, that is, that it forms part of a biocenosis and not of all those on the planet at the same time. This concept It is very interrelated with the ecological niche, which we have briefly touched on in previous lines.. Some of these barriers are the following:

• Physical barriers: land, rivers, landforms, cliffs and many other formations of the landscape.
• Climatic barriers: living beings develop and adapt to specific climatic conditions. Therefore, they cannot extend beyond a certain range without dying.
• Biological barriers: for example, the absence of food. Maybe a cow can handle desert weather, but without grass, she wouldn't last long in the dunes.

These barriers between communities or biocenoses create complex but extremely interesting places from a biological point of view: ecotones. This is a transition zone, where all the biological components are in tension. Here the highest rates of energy exchange occur and, therefore, they are usually the places with the greatest richness of biodiversity.

Summary

As you will have been able to verify, every zoological term entails a series of widely interconnected previously established concepts. We cannot understand a biocenosis, for example, without taking into account the ecological niche of the species, trophic pyramids, barriers, biomass and the productive capacity of an ecosystem, for example.

After all, all these terms condition the variety of populations of living beings that settle on a physical space. The biotope and the biocenosis create an ecosystem, but do not forget that neither of these two terms is immovable and infinite: ecosystems They change continuously on a small or large scale, which is why the biocoenosis can undergo many variations throughout its journey. evolutionary.

Bibliographic references:

• Biomass, mendoza.org. Collected on January 31 in https://www.mendoza.conicet.gov.ar/portal/enciclopedia/terminos/Biomasa.htm#:~:text=La%20cadena%20de%20biomasa%20representa, energ%C3%ADa%20estimated%20in%20a%2090%25.
• Biological community, aitanatp.com. Collected on January 31 in http://www.aitanatp.com/nivel6/ecosist/comunidad.htm
• Gosset, A., Ferro, Y., & Durrieu, C. (2016). Methods for evaluating the pollution impact of urban wet weather discharges on biocenosis: a review. Waterresearch, 89, 330-354.
• The biosphere, UM.es. Collected on January 31 in https://www.um.es/sabio/docs-cmsweb/materias-may25-45/tema_5.pdf
• Topic 2: Ecology, environmental factors and relationships in ecosystems, apuntesmareaverde.org.