WHAT IS THE DYNAMICS OF ECOSYSTEMS? - BIOLOGY - 2025

The dynamics of ecosystems refers to the set of continuous changes that occur in the environment and in its biotic components (plants, fungi, animals, among others).

Both the biotic and abiotic components that are part of an ecosystem are found in a dynamic balance that gives it stability. Similarly, the process of change defines the structure and appearance of the ecosystem.

Source: By LA turrita, from Wikimedia Commons

At first glance you can see that ecosystems are not static. There are rapid and dramatic modifications, such as those that are products of some natural disaster (such as an earthquake or fire). In the same way, the variations can be slow like the movements of the tectonic plates.

The modifications can also be products of the interactions that exist between the living organisms that inhabit a certain region, such as competition or symbiosis. In addition, there are a series of biogeochemical cycles that determine the recycling of nutrients, such as carbon, phosphorus, calcium, among others.

If we can identify the emergent properties that arise thanks to the dynamics of ecosystems, we can apply this information to the conservation of species.

Definition of ecosystem

An ecosystem is made up of all organisms that are interrelated with the physical environment in which they live.

For a more precise and sophisticated definition, we can cite Odum, which defines ecosystem as “any unit that includes all organisms in a given area interacting with the physical environment with a flow of energy through a defined trophic structure, biotic diversity and material cycles ”.

Holling, for his part, offers us a shorter definition "an ecosystem is a community of organisms whose internal interactions between them determine the behavior of the ecosystem more than external biological events."

Taking both definitions into account, we can conclude that the ecosystem is made up of two types of components: biotic and abiotic.

The biotic or organic phase, includes all living individuals in the ecosystem, call it fungi, bacteria, viruses, protists, animals and plants. These are organized at different levels depending on their role, be it producer, consumer, among others. On the other hand, abiotics comprise the non-living elements of the system.

There are different types of ecosystems and they are classified depending on their location and composition in various categories, such as tropical rain forest, deserts, grasslands, deciduous forest, among others.

relationships between living beings

Ecosystem dynamics are not strictly determined by variations in the abiotic environment. The relationships that organisms establish with each other also play a key role in the exchange system.

The relationships that exist between individuals of different species affect a variety of factors, such as their abundance and distribution.

In addition to maintaining a dynamic ecosystem, these interactions have a key evolutionary role, where the long-term result is processes of coevolution.

Although they can be classified in different ways, and the boundaries between the interactions are not precise, we can mention the following interactions:

Competition

In competition, two or more organisms affect their growth and / or reproduction rate. We refer to intraspecific competition when the relationship occurs between organisms of the same species, while the interspecific occurs between two or more different species.

One of the most important theories in ecology is the principle of competitive exclusion: “if two species compete for the same resources, they cannot coexist indefinitely”. In other words, if the resources of two species are very similar, one will end up displacing the other.

This type of relationship also includes competition between males and females for a sexual partner to invest in parental care.

Exploitation

Exploitation occurs when "the presence of a species A stimulates the development of B and the presence of B inhibits the development of A".

These are considered antagonistic relationships, and some examples are predator and prey systems, plants and herbivores, and parasites and hosts.

Exploitation relationships can be very specific. For example, a predator that only consumes a very closed limit of prey - or it can be wide, if the predator feeds on a wide range of individuals.

Logically, in the predator and prey system, the latter are the ones that experience the greatest selective pressure, if we want to evaluate the relationship from an evolutionary point of view.

In the case of parasites, these can live inside the host or be located outside, such as the well-known ectoparasites of domestic animals (fleas and ticks).

There are also the relationships between the herbivore and its plant. Vegetables have a series of molecules that are unpleasant to the taste of their predator, and these in turn develop detoxification mechanisms.

Mutualism

Not all relationships between species have negative consequences for one of them. There is mutualism where both parties benefit from the interaction.

The most obvious case of mutualism is pollination, where the pollinator (which can be an insect, a bird or a bat) feeds on the energy-rich nectar of the plant and benefits the plant by promoting fertilization and dispersing its pollen.

These interactions do not have any kind of awareness or interest on the part of the animals. That is, the animal in charge of pollination does not seek at any time to "help" the plant. We must avoid extrapolating human altruistic behaviors to the animal kingdom to avoid confusion.

Biogeochemical cycles

In addition to the interactions of living things, ecosystems are influenced by various movements of the main nutrients that take place simultaneously and continuously.

The most relevant involve the macronutrients: carbon, oxygen, hydrogen, nitrogen, phosphorus, sulfur, calcium, magnesium and potassium.

These cycles form an intricate matrix of relationships that alternates recycling between living parts of the ecosystem with non-living regions - be it bodies of water, atmosphere and biomass. Each cycle involves a series of steps of production and decomposition of the element.

Thanks to the existence of this cycle of nutrients, the key elements of the ecosystems are available to be used repeatedly by the members of the system.

References

1. Elton, CS (2001). Animal ecology. University of Chicago Press.
2. Lorencio, CG (2000). Community ecology: the paradigm of freshwater fish. Sevilla University.
3. Monge-Nájera, J. (2002). General biology. EUNED.
4. Origgi, LF (1983). Natural resources. Euned.
5. Soler, M. (2002). Evolution: the basis of Biology. South Project.