11 julio, 2024

Ecological balance: causes, factors, properties and examples

He ecological balance It is defined as a state, observable in ecological communities in ecosystems, in which the composition and abundance of species remains relatively stable for a long time.

The idea of ​​a natural balance is part of many philosophical systems and religions. There are those who support the Gaia hypothesis, according to which the biosphere would act as a system that coordinately maintains, as a supraorganism, the global ecological balance.

The notion of ecological balance underpins many environmental attitudes in the general public. Ecologists prefer to think in terms of biodiversity conservation, sustainable development, and environmental quality.

Stable ecosystems, in which there is or appears to be a clear ecological balance, abound in nature. For this reason they figure prominently in the scientific and informative literature. However, there are also unstable ecosystems that have historically received less attention.

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Causes

Ecological balance is the result of the ability of ecological communities to gradually recover, through a process of ecological succession, their original stability, or ecological climax, which has been lost due to disturbance, be it environmental, biotic, or human. that alters the composition and abundance of species.

The term «ecological succession» refers to the process of directional change of a community after having suffered a major disturbance. This change takes place in stages and is expressed in the composition and abundance of species, which tend to increase their diversity. Ecological succession has been extensively studied in plant communities.

As a community goes through the stages of ecological succession, it is considered to be out of equilibrium. Upon reaching the final stage of succession, or ecological climax, the composition of the community is stable, which is why it is considered to be in a state of relative equilibrium.

The ecological balance is a dynamic steady state (homeostasis). Feedback between populations continually compensates, dampening its effect, for minor changes in community population composition and abundances caused by abiotic and biotic factors. As a result, the community returns to its initial appearance.

factors

The ecological balance is the product of the dynamic interaction of two types of factors. First, external disturbances, represented by events, usually of short duration, that cause changes in the composition and abundance of species.

Second, the neutralization of said changes by ecological interactions between the populations that make up the community.

External disturbances can be biotic factors that act episodically. For example, the irruption of migratory species, such as locust plagues in Africa, or pathogens that cause epidemics.

Disturbances can also be sudden abiotic factors, such as hurricanes, floods, or fires.

The ecological interactions that determine the existence of ecological balance include direct (carnivore/prey, herbivore/plant, pollinator/flower, frugivore/fruit, parasite/host) and indirect (example: carnivore/plant) interactions between the populations that make up each community.

As a result of feedback effects inherent to such interactions, the change in the size of a population is corrected, returning to its equilibrium level, in which the oscillations in the number of individuals are minimal.

Feedback effects are very complex, and therefore particularly vulnerable to disruption by human action, in highly diverse ecosystems, such as tropical rainforests and coral reefs.

main properties

During ecological equilibrium, communities reach a relative stability, or steady state, in species composition and abundance. Said stability is defined in terms of four main properties, namely: constancy, resistance, resilience and persistence. The latter is also known as inertia.

Constancy is the ability to remain unchanged. Resistance is the ability to not undergo changes as a result of disturbances or external influences. Resilience is the ability to return to the original steady state after a disturbance. Persistence is the ability of populations to be conserved over time.

Constancy can be measured by standard deviation, or yearly variability. Resistance through sensitivity, or buffering capacity. The resilience through the return time, or the magnitude of the deviation that allows said return. Persistence through the mean time to extinction of a population, or other irreversible changes.

For example, an ecosystem that cyclically oscillates around a state, such as that described by the Lotka-Volterra equations to describe the interaction between predators and prey, can be classified as resilient and persistent.

However, it cannot be considered as constant and resistant. In a case like this, two conditions are satisfied that allow it to be considered stable.

Necessary conditions

The assumption of competition between species plays a major role in the concept of ecological balance. This assumption assumes that in communities there is a balance between productivity and respiration, inward and outward energy flow, birth and death rates, and direct and indirect interactions between species.

The assumption of interspecies competition also assumes that, even in communities that are not in the state of ecological climax, some degree of ecological balance probably exists, and that on oceanic islands there is a balance between immigration and extinction of ecologically equivalent species. .

The survival of the species that make up a population depends on the persistence of those same species at the metapopulation level. The exchange of individuals and the recolonization between populations of the same species that inhabit nearby communities maintains genetic diversity and makes it possible to remedy local extinctions.

At the metapopulation level, survival implies: a) populations distributed in discrete microhabitats; b) microhabitats close enough to allow their recolonization from other microhabitats; c) higher probability of extinction at the population level than at the metapopulation level; and d) low probability of simultaneous extinction in all microhabitats.

examples

Consider the case of wolves that, after many decades of being exterminated by ranchers, were reintroduced to Yellowstone National Park in the United States to restore the ecological balance lost due to the overpopulation of large herbivorous mammals.

The initial growth of the wolf population radically decreased the populations of herbivorous mammals, which in turn put a limit on the size of the population of the former (fewer herbivores means that many wolves do not have enough food and starve, or they do not produce puppies).

The lower and more stable levels of herbivore populations thanks to the presence of also stable populations of wolves allowed the reappearance of forests. This in turn allowed the recolonization of Yellowstone by large numbers of species of forest birds and mammals. In this way, the park recovered its original splendor and biodiversity.

Other examples of communities in apparent ecological balance are found within national parks and marine reserves where laws protecting them are enforced, or in remote areas with low human densities, particularly when the inhabitants are indigenous who make little use of technology. modern.

Consequences of your loss

The current rate of environmental destruction far exceeds the capacity of ecosystems to recover their natural ecological balance.

The situation is unsustainable and cannot continue for long without seriously harming humanity. The loss of biodiversity makes it increasingly difficult to find species to reconstitute natural communities and ecosystems.

For the first time in its history, humanity is facing three dangerous disturbances on a planetary scale: 1) climate change, one of the most obvious facets of which is global warming; 2) pollution and acidification of the oceans; and 3) an enormous loss, at unprecedented speed, of global biodiversity.

These large-scale disturbances will hit the youngest members of current generations and future generations hard. There will be large numbers of climate refugees. Fishery resources will decrease. It will look like a world devoid of many of the wild plant and animal species we are used to.

How to keep it?

On this subject, the consultation of the work of Ripple et al. (2017). These authors point out that in order to achieve the transition towards a global ecological balance it would be necessary:

1) Create nature reserves that protect a significant fraction of the planet’s terrestrial and aquatic habitats.

2) Stop the conversion of forests and other natural habitats in areas under intensive exploitation.

3) Restore large-scale native plant communities, especially forests.

4) Repopulate large regions with native species, particularly top predators.

5) Implement policies to remedy the loss of fauna, the exploitation and trade of endangered species, and the global crisis caused by the consumption of wild animals.

6) Reduce food waste.

7) Promote the consumption of plant foods.

8) Reduce human population growth through education and voluntary family planning.

9) Educate children in the appreciation and respect of nature.

10) Channel monetary investments towards positive environmental change.

11) Design and promote green technologies, reducing subsidies for the consumption of fossil fuels.

12) Reduce economic inequality and ensure that prices, taxes and incentives take into account the environmental cost.

13) Unite nations to support these vital goals.

References

Blonder, B., Nogues-Bravo, D., Borregaard, MK, Donoghue, JC, Jørgensen, PM, Kraft, NJB, Lessard, J.-P., Morueta-Holme, N., Sandel, B., Svenning, J.-C., Violle, C., Rahbek, C., Enquist, BJ 2015. Linking environmental filtering and disequilibrium to biogeography with a community climate framework. Ecology, 96, 972–985. Cuddington, K. 2001. The “balance of nature” metaphor and equilibrium in population ecology. Biology and Philosophy, 16, 463–479. DeAngelis, DL, Waterhouse, JC 1987. Equilibrium and nonequilibrium concepts in ecological models. Ecological Monographs, 57, 1–21. Grimm, V., Schmidt, E., Wissel, C. 1992. On the application of stability concepts in ecology. Ecological Modelling, 63, 143–161. Looman, J. 1976. Biological equilibrium in ecosystems: a theory of biological…

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