Core Ecological Concepts

Core Ecological Concepts

Understanding the patterns and processes by which nature sustains life is central to ecological literacy.

Fritjof Capra says that these may be called principles of ecology, principles of sustainability, principles of community, or even the basic facts of life. In our work with teachers and schools, the Center for Ecoliteracy has identified six of these principles that are important for students to understand and be able to apply to the real world.

Recognizing these core ecological concepts is one of the important results of our guiding principle, "Nature Is Our Teacher," which is described in the "Explore" section of this website. We present them again here for the guidance they can provide to teachers as they plan lessons as part of schooling for sustainability. 

All living things in an ecosystem are interconnected through networks of relationship. They depend on this web of life to survive. For example: In a garden, a network of pollinators promotes genetic diversity; plants, in turn, provide nectar and pollen to the pollinators.



Nested SystemsNested Systems
Nature is made up of systems that are nested within systems. Each individual system is an integrated whole and — at the same time — part of larger systems. Changes within a system can affect the sustainability of the systems that are nested within it as well as the larger systems in which it exists. For example: Cells are nested within organs within organisms within ecosystems.


Members of an ecological community depend on the exchange of resources in continual cycles. Cycles within an ecosystem intersect with larger regional and global cycles. For example: Water cycles through a garden and is also part of the global water cycle.


Each organism needs a continual flow of energy to stay alive. The constant flow of energy from the sun to Earth sustains life and drives most ecological cycles. For example: Energy flows through a food web when a plant converts the sun's energy through photosynthesis, a mouse eats the plant, a snake eats the mouse, and a hawk eats the snake.  In each transfer, some energy is lost as heat, requiring an ongoing energy flow into the system.

All life — from individual organisms to species to ecosystems — changes over time. Individuals develop and learn, species adapt and evolve, and organisms in ecosystems coevolve. For example: Hummingbirds and honeysuckle flowers have developed in ways that benefit each other; the hummingbird's color vision and slender bill coincide with the colors and shapes of the flowers.

Dynamic BalanceDynamic Balance
Ecological communities act as feedback loops, so that the community maintains a relatively steady state that also has continual fluctuations. This dynamic balance provides resiliency in the face of ecosystem change. For example: Ladybugs in a garden eat aphids. When the aphid population falls, some ladybugs die off, which permits the aphid population to rise again, which supports more ladybugs. The populations of the individual species rise and fall, but balance within the system allows them to thrive together.

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