Grey concrete, the sound of engines and construction works, a night sky glowing orange with LED light and not a star in sight. The only other signs of life beyond humans include cats, dogs, pigeons, rats and cockroaches.
The modern human ecosystem. Exaggerated.
In reality, an ecosystem refers to a geographic area, the living organisms within it and the interactions between them and their environment, including abiotic factors such as weather, temperature and moisture levels.
They are made up of interdependent habitats with important processes that can have far reaching consequences.
The term is frequently used in other domains, which hints at its interdisciplinary potential.
What is a Habitat?
A habitat refers to the specific part of an ecosystem where a living organism makes its home, finds shelter and acquires the resources it needs to survive.
Two organisms can share an ecosystem, but also occupy entirely different habitats within it.
What is the Energy Flow of an Ecosystem?
For an ecosystem to thrive, it requires energy, which begins at our planet’s primary source; the sun.
Producers, such as plants, are able to use light from the sun to provide the energy they need to survive, which in turn feeds consumers, enabling life to be sustained.
This flow of energy can be described by food chains and food webs.
Food Chains and Food Webs
A food chain describes which living organisms feed upon which in order to survive. A food web refers to the entire network of chains that exist within an ecosystem, showing how they are connected and how dependent each part is on the others.
Food chains can be divided into what are called trophic levels, to form a trophic pyramid; a simplified way to show where living organisms sit within a food web.
The base of the pyramid is formed by producers, also known as autotrophs. They are organisms capable of producing their own energy and obtain nutrients without consuming other living organisms.
Consumers, also known as heterotrophs, rely on other living organisms for their nutrients and energy. They are typically divided into primary, secondary or tertiary consumers, with those higher up in the pyramid preying on those below.
Decomposers
Often overlooked in simpler diagrams, decomposers such as fungi and bacteria break down dead organic matter and return nutrients to the soil. Without them the flow of energy and matter would simply stop.
What is Nutrient Cycling?
Nutrient cycling refers to the movement and reuse of matter, such as carbon, nitrogen and phosphorus, between the biotic and abiotic elements of an ecosystem.
Unlike energy, which flows in one direction and is lost at each trophic level, nutrients are recycled continuously. Carbon fixed by plants returns to the atmosphere through respiration and decomposition. Nitrogen moves between soil, organisms and atmosphere through a series of bacterial processes. Phosphorus cycles more slowly, moving through rock, soil and living organisms over geological timescales.
Why Ecosystems Matter
Ecosystems are complex systems. To try and understand them is to try and understand the world you literally inhabit.
When healthy, they provide clean air and fresh water, keep soil fertile, support pollinators and regulate the climate. Things that technology either can’t replicate or whose long-term impact is unknown.
Changes in one part affects another, either positively or negatively. Simple examples include the increase in water temperature causing higher mortality in mussels or the restoration of pine groves to prevent desertification.
Both impact the local ecosystem and they both have a human impact. Mussels are a local food source as well as a major export for Galicia, while halting the advancing dunes of Guardamar protected local agriculture.
The financial impact isn’t really the point. They are straightforward illustrations of a complex system where we can see cause and effect. Reality is far more intricate and unlikely to be entirely deciphered.
But learning how ecosystems work can be more than just an exercise in biology. It can be a way of thinking about complexity itself; how systems behave and how well they can absorb shock. Or not. And that can be a transferable skill.