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Balance in Natural Comunities

Balance = Homeostasis

A natural community is a combination of a great number of species. For example, a roadside pond is a community composed of thousands of species (duckweed,turtles, water lilies, muskrats, algae, zooplankton, cattails, snails, ducks, bacteria, etc.) which live together and connect to one another in a great variety of ways.

An ecosystem is a collection of interlinked communities, and is sometimes used to mean a single larger community. 

An ecosystem regulates itself. Homeostasis is the dynamic equilibrium among the living members of an ecosystem, and with their ever-changing environmental conditions, such as wind, rainfall, nutrient availability, air quality, and climate.

Remind yourself that homeostasis requires no thought or intention--it is the wisdom of the body; it is the wisdom of the living system. 

Ecosystem homeostasis is achieved through intricate, interlocking sequences of feedback loops.

Attack-Avoidance as Homeostasis

In mammals and birds especially, members of the same species spend a lot of time and energy harassing each other, chasing each other, fighting (but not hurting each other much), and avoiding each other. This is called Attack-Avoidance behavior.

If you have spent time watching squirrels, or birds, or kids on playgrounds, you have probably noticed a lot of threats and hassling, and some avoidance or running, or flying, away. You may also have noticed that members of different species mostly just ignored each other, unless one just got too close.

If you watch gray squirrels under a bird feeder eating spilled seed, and a chipmunk arrives, the squirrels pretty much ignore the chipmunk. But if a new squirrel arrives, all the squirrels visibly react to its presence. One may move out of its way, another may charge and attack and chase the new arrival. If a second chipmunk arrives, the first chipmunk must react.

Attack-Avoidance behavior within a species often works as a dispersal agent, so that members of a population are evenly distributed over an area. This insures that everyone gets to eat.

Attack-Avoidance behavior also functions as a kind of social glue that creates social bonds and gives coherence to the social structure of a population.

The whole community benefits from the dynamic balancing of each of its member populations. 


Overcrowding Homeostasis

When a population of mammals explodes its numbers for some reason, we discover an entirely different homeostatic process. 

In many species, especially in small consumers such as mice, rabbits and lemmings, over-crowding creates an increasing stress that damages the thyroid gland, which manufactures essential hormones. 

When population densities reach a critical point, the stress becomes extreme and much of the population simply drops dead from endocrine (hormone) system damage.


In some species, such as snowshoe hares and lemmings, population density is cyclical. It gradually expands year after year--but before the environment is badly damaged from overfeeding, this strange homeostatic process kicks in, most of them crawl into their dens and die, and the population problem is solved--until the next imbalance.


Lemmings are small rodents that live near and in the tundra north of the conifer forests of North America, Europe and Asia. When their population cycle peaks and food runs out, they sometimes do migrate, but more commonly their crowding-induced thyroid disease kills them so suddenly that their disappearance has given rise to stories that they have all flung themselves into the sea or. The truth is that they are in their burrows, quite dead, which is even more strange than the stories people make up about their sudden disappearance.

Most natural populations never explode in numbers; if they do, it's a good bet that human interference has removed a population control from the community. When all the predators of deer (wolves, cougars, and so forth) are removed from a community, populations of deer explode. Sometimes the homeostatic dispersal process works, and if there are places to go, the deer simply spread out. But of course, humans have allocated most space in the world to their own use, and when there are no places to go, crowded deer suffer from thyroid disease too, like the smaller animals.

Prey Abundance and Homeostasis

When the prey of predators such as owls is super-abundant, as at the peak of lemming and hare cycles, the predator will have more young. The snowy owl, for example, will lay up to eleven eggs at peak prey abundance where it normally lays three. So the predators become as super-abundant as prey. If a niche opens in an ecosystem, life fills it as quickly as possible.

The prey population crashes. The predators have little choice. They can travel, or starve.

When birds travel because of a sudden shortage of food, they fly to places where they are rarely seen, especially in winter. In 2005, great gray owls irrupted into the northern United States. Many died from traffic, and many died because they were in poor condition for the long migration south.

Large owls are early breeders. Great horned owls begin to nest in late January in Minnesota, and several species of owls are nesting by late February. The homeostatic process that kicks in here, especially for irruptive owls, is powerful. They often do not breed at all, because when it's time to court and bond, they are far from home territories. Also, females are often in poor condition to grow eggs during irruptions. The result is that predator and prey numbers quickly return to homeostasis.


Homeostasis in Reproduction: Multiple Births

Another homeostatic process which regulates population is multiple births. In some species, such as deer, crowding results in single births. When the same species is not crowded, twins are the rule.

Populations adjust themselves to "undercrowding" as well as to overcrowding. If there is a niche (a way to make a living) available in an ecosystem, life will fill it.


Predation as Homeostasis

Predation can also be seen as a homeostatic process of communities. Predator/prey relationships have an odd element of cooperation in them.

Predators tend to kill the weakest members of the prey population, which include animals who are ill, old, or very young.

Wasp about to paralyze a spider Osprey carries a fish back to the nest Otter has a big fish

Predators are unlikely to kill the strongest and fastest prey, who survive to pass along those traits to their offspring.

Through natural selection, predation shapes the prey species as much as it shapes the predator.

In other words, deer run fast because the slow ones were eaten.

The conclusion is that predation helps regulate the health and stability of the community.

In natural communities, what is good for the community is not always what is good for single lives.



Natural ecosystems are sustainable. That means that they can maintain themselves with some integrity. It does not mean that they remain in a fixed state; nothing can. Sustainable systems can and do change.

Sustainability is an emergent property of ecosystems. An emergent property is a behavior or quality of a system that demonstrates synergy (the whole is greater than the sum of its parts).
Emergent properties are not features of system parts
Emergent properties cannot be predicted
Emergent properties prove that nature is creative

Take water as an example. A molecule of water is a simple system, with three parts, two atoms of hydrogen and one atom of oxygen. When they are separate atoms, they are not wet. When those three atoms incline themselves to come together, they create H2O, water, which has many emergent properties (wetness, liquidity, solidity, etc.), none of which are predictable.

When communities of microscopic lives began to organize themselves some billions of years ago, they discovered that they could be self-maintaining, thus sustainable. Bacteria organized themselves into complex layered communities called biofilms, and still do. Although bacteria are too small for us to directly perceive, we can perceive biofilms easily. They are the slightly slimy film that coats unbrushed teeth. Biofilms cover every moist surface on earth.

Whether microscopic or macroscopic, organisms are all enmeshed in a complex web of relationships with other lives and with their environment. These webs of life are ecosystems, and they are generally sustainable.

Humanity is now realizing that our societies, especially industrialized societies, are not sustainable and are far from any sort of homeostasis. A few scientists and thinkers are deeply engaged in finding solutions to this enormous set of problems. In brief, an unsustainable system will collapse.

Ecosystems are "complex dynamic adaptive systems," the key word being adaptive. An ecosystem can be "perturbed," which means that something outside it has changed in a way that requires an ecosystem response. Air quality, for example, is changeable, or climate warming.

Ecosystems have the ability to "ride out" many pertubations. This is called resilience. Resilience is an emergent property of biodiversity.


The principle of biodiversity is simple:

In any living community, the more different kinds of organisms there are, the stronger that community will be.

In other words, The more variety of life-forms in an ecosystem, or the more differences there are among the inhabitants, the healthier the community will be, and the more adaptable and resilient the community will be.

This is fundamentally important knowledge that has profound implications for human societies.  Biodiversity may be the most important idea on earth.

But we don't get it.

Most people know deep down that Earth is in trouble, and we are in trouble, but dare not think about it. Most of us insist on seeing the Earth through rose-colored glasses.

The word “biodiversity” names ideas that should carry enormous urgency for us. But they don’t.

Why is that? We don’t, or can’t, seem to care all that much about it. Why not? The evidence is that we find it an extraordinarily difficult concept to grasp.

We resist understanding biodiversity It seems that we cannot “buy into” biodiversity because the concept conflicts so completely with our experience of the world.

Biodiversity is counter–intuitive for us.
Our minds are simply not prepared to accept it as true

What Gets in Our Way?
Wearing Machine-Colored Glasses


Several things obstruct our understanding:

We still believe that “It’s a jungle out there!” and simultaneously believe the contradictory statement that humans are above Nature. This is called “doublethink.”
We see the physical world through “machine-colored glasses.”

For centuries, Western civilization has been simultaneously denying that humans are animals, and busy claiming that we have evolved beyond our animal origins to the point where we control nature rather than it controlling us.

Our special relationship with a Creator, many claim, makes our membership in Nature irrelevant, because this Earth and this life was created for humans as a preparation for eternal life somewhere else. This is a way of saying that the rules don’t apply to us: “Hey, you can’t arrest me—I’m the Mayor’s kid!” This is also a way of saying that, in the long run, it doesn’t really matter what we do to Earth, for it is only a way-station on our trip to Eternity.

We wear machine-colored glasses. Even ecologists, who should know better, describe natural processes as mechanisms.

For 200 and more years, Westerners have been seeing the world through machine glasses. By 1661, philosophers had begun to formulate a new conception of Nature as an intricate, impersonal, and inert machine. Seventeenth Century science, in the persons of Descartes and Isaac Newton, left us with a view of the universe as an enormous mechanism, a sort of clockwork set in motion by its Creator that has been ticking along ever since.

In other words, our society has inherited a way of seeing Nature as a mechanism, which operates under certain rules, or laws, like any machine, so it behaves like a machine. And in our mechanically–sophisticated society, there are certain things everyone ‘knows’ about machines.

We ‘know’ that the more parts a machine has, the more vulnerable it is to failure. The space shuttle has an enormous number of parts. It breaks down. Complication in machines is a problem; a machine that is too complicated is likely to break. In the Machine–World, More is Less.

Monocultures: Where More is Always Less

Monoculture is the practice of growing single crops on a piece of land, often for year after year. Midwestern cornfields are a typical monoculture. Usually that crop is one bred variety of one species.

Monoculture is also found in forestry, where a forest complex has been clearcut and re-planted in only one species, often poplar, sometimes one species of pine.
We know the adage, “Don’t put all your eggs in one basket,” but it seems to be an extraordinarily hard lesson.

Monoculture is a managed refusal of diversity.

The results of monoculture include:

heavy use of chemical fertilizers
heavy use of chemical poisons (herbicides, insecticides)
increased susceptibility to diseases
low tolerance to stresses of drought or temperature
reduced resistance to insects
crop failures resulting in famines
reduced soil fertility
increased soil erosion
permanent loss of genetic variety in the crop species
increased habitat for “pest” species
reduced habitat for beneficial species

The way we raise chicken, turkeys, pigs, lambs, calves, and cattle is near monoculture. We use only a few breeds, all but cloned for maximum food production and turned into factory products.

Animals raised in monoculture are so highly susceptible to disease that we routinely dose them with antibiotics.

Oops! We just discovered that bacteria and insects evolve much faster than we ever dreamed, and this use of antibiotics has quickly created many resistant organisms that endanger our own health, not just that of our meat.

Not long ago, scientists cloned a sheep named Dolly. Cloning of food animals, if it becomes widespread, will eventually lead to a true monoculture, for only the best milk-producing cows will be cloned, perhaps thousands of times over, and only the best ham-producing pigs will be cloned, and only the best steak-producing cattle will be cloned.

The result will be very odd. We may all end up eating the same animal, over and over. The species of animals will lose genetic diversity, and the clones will be increasingly vulnerable to disease and defects, because of a process called genetic drift.

Wearing Green–Colored Glasses:
When More Really Is More

All of our experiential intuitions of both the mechanical and social worlds tell us that More is Less. They tell us that complexity equals complication which is a bad thing.
But in Nature, in the actual workings of life on earth, More Really is More. Nature's system processes are synergistic (wholes are more than the sum of their parts).

The First Principle of Biodiversity: In any living community, the more different kinds of organisms there are the stronger that community will be.

There was an older knowledge and model of reality that the machine glasses replaced. Our re-discovered awareness of ecology marks a return to our ancient understanding of nature, a knowledge we held for many thousands of years.

For that time, we saw the world through Green–colored glasses. That is, we saw the world and its workings through a perceptual set and knowledge that we acquired as we evolved into human beings, as we became ourselves.

These green glasses we are beginning to wear again show us Earth’s ecosystems as they really are: the flourishing of diversity is strength; the flourishing of diversity is resilience; the flourishing of diversity is health. Complexity is related to success more than breakdown. We are beginning to know again:

All species in a community interlive (are essentially symbiotic).
Everything is connected to everything else, and all lives are interdependent
In a natural community, all members benefit and all members suffer interdependently. Each has its role.

Cooperation is a force in nature as powerful as competition. A diversity of organisms is a living example of synergy.

Green-colored glasses look at complexity and see blessing and strength.

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Explore Further in Balance

Balancing the Planet: Gaia Theory
Balance Introduction and Feedback Loops
Return to Ecology Index

Explore the Biosphere

Biosphere: Introduction
Biosphere as Place: Introduction
Biosphere as Ocean: Life Zones
Biosphere as Ocean Floor: Benthic Biomes One
Biosphere as Ocean Floor: Benthic Biomes Two
Biosphere on Land: Terrestrial Biomes
Biosphere on Land: Anthropogenic Biomes
Biosphere as Process: Introduction
Biosphere Process: Floating Continents, Tectonic Plates
Biosphere Process: Photosynthesis
Biosphere Process: Life Helps Make Earth's Crust
Biosphere Process:
Rock Cycle--Marriage of Water and Rock
Biosphere Process: Marriage of Wind and Water
Biosphere Process: Gas Exchange
Biosphere as An Expression of Spirit
The Ecological Function of Art
The Earth Goddess
The Tree of Life
The Green Man
Earth Art
Biosphere as Community
Biosphere Microcosm: Bacteria and Archaea
The Procaryote Domain
Biosphere Microcosm: Germs
Biosphere Community: The Eucaryote Domain
Biosphere Community: Protists 1: Algae
  Biosphere Community: Protists 2: Protozoa
Biosphere Community: Plants: What's New?
Biosphere Community: Kinds of Plants--Major Groups
Biosphere Community: Plant Defense
Biosphere Community: Plant Pollination
Biosphere Community: Plant Seed Dispersal
Biosphere Community: Kingdom Animals
Biosphere Community: Kingdom Fungi
Biosphere Community: Six Great Extinctions
Return to Ecology Index


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