Nature’s Energy Flow

Human life, and all other life, is totally dependent upon Nature. Our arrogant modern humanity is unable to accept this dependency. However, it is a fact that Nature captures, contains, and operates the processes that provide you with the energy that you need to live.

Energy Is Essential To All Life On Earth

Nothing in our Universe happens without the existence of both energy and the pathways by which this energy flows. A destruction or hindrance of energy or its pathways, whether by man or by Nature, can bring ecological disaster.

The major source of Earth’s energy is the sun. The sun’s atomic furnace transmits its energy outward in the form of photons – a fundamental particle of light. Our earth receives some of this photon energy, filters it through our atmosphere, and makes it available to the network of living and non-living objects on the earth’s surface.

On Earth, the network of energy pathways begins with the leaves of green plants which receive the sun’s energy. A chemical within this leaf, called chlorophyll, receives the sun’s energy. Along with carbon dioxide from the air, chlorophyll creates a chemical called carbohydrate – a form of sugar. This carbohydrate is the warehouse that stores the energy that has been received from the sun. In this way, the sun’s energy is transformed into a form of energy that is useful to the plant and to animals that eat the plant.

Animals, like ourselves, then eat the plant leaves. In doing so, the animal’s body transforms the stored sun’s energy within the leaf’s sugars into a chemical compound called “ATP”. ATP stores and then releases life energy for use by an organism.  In addition to eating plants, we humans, and other meat eating creatures, receive and transform energy by eating other animals who had previously eaten plants.

Energy Is Both Transported And Transformed

There are two important processes that take place within this energy chain. First, energy is transported from the sun and then from one organism to another. Then, within each organism, energy is transformed into a useful form. So, in order to live, every plant and every animal within the entire web of life both transports and transforms energy. The energy conduits that serve to transport and transform life energy of all plants and animals is a highly complex  network that is called an “ecosystem”. The energy networks within ecosystems are sometimes called food webs.

The science of ecology focuses on how energy flows within ecosystems. The term ‘trophic’ refers to anything related to the flow of energy in Nature’s food webs.  In ecology, the term “trophic level” is the position that an organism occupies in a food chain. In other words, a trophic level describes what an organism eats, and who eats that organism.

Nature’s Energy Flow Can Change Within Ecosystems

A “trophic cascade” is a change in the transportation and transformation of energy flow. This is often triggered by humans adding or removing an organism within a food web. Often, a trophic cascade results in dramatic changes in the flow of energy which alters an ecosystem’s structure and nutrient cycling.

The study of trophic cascades provides living demonstrations of how changes in energy flow can result in radical changes in ecosystems. In particular, these studies can show how mankind’s uninformed actions can alter Nature’s flow of energy with possibly disastrous results.








The story of the wolves at Yellowstone National Park is a living demonstration of mankind’s alteration of trophic cascades which resulted in an adverse alteration of Nature’s energy flow.  There is no better example than the Yellowstone wolf. The story of the eradication of the wolf in and near Yellowstone National Park in the early 1900s, and the wonder of Nature’s recovery when the wolf was reintroduced in 1995 is an amazing demonstration of the positive impact of key predators on an ecosystem’s energy flow.

The story is best told through an amazing video, “Lords of Nature” which is narrated by actor Peter Coyote. There is a wonderful discussion guide  in PDF format that might be of interest to educators.

Another amazing video is “How Wolves Change Rivers” . This short video, narrated by  George Monbiot, provides a wonderful description of the trophic cascade that starts with the Yellowstone wolves and ends with the alteration of the flow of rivers when wolves were eradicated. It is living evidence that mankind’s alteration of Nature’s web of life can produce unwanted and unpredictable changes to an ecosystem and its physical environment.

George Monbiot narrates another wonderful video,  “How Whales Change Climate“. He describes how mankind has changed our earth’s energy flow by killing huge numbers of whales.

“When whales were at their historic populations before their numbers were reduced, it seems that whales might have been responsible for removing tens of millions of tonnes of carbon from the atmosphere every year. Whales change the climate. The return of the great whales, if they are allowed to recover, could be seen as a benign form of geo-engineering. It could undo some of the damage we have done, both to the living systems of the sea and to the atmosphere.”

Here are some other examples of trophic cascades:

  • Sea Otters – Sea otters eat urchins, which eat kelp. Otters keep the urchin population in check so that the kelp population (and its reliant ecosystem) can flourish.
  • Blue Crabs of Salt Marshes – Blue crabs eat snails. Snails can threaten a salt marsh by consuming enough marsh grass to turn the marsh into a mudflat.
  • Jaguars & Other Rainforest Predators – Similar to the wolves of Yellowstone, jaguars and other rainforest predators keep the herbivore population from growing out of control.


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