The Food Web Simplified
When thinking about how plants and wildlife interact, we often hear the terms food chain and food web. A food chain is a specific sequence of organisms through which energy and nutrients pass as one organism eats another (e.g., Grass → Grasshopper → Frog → Snake → Hawk), while a food web is a complex network of interconnected food chains.
As gardeners trying to understand how our gardens support—or fail to support—the local ecosystem, I think a good starting point is to focus on a simplified, abstract food chain that highlights the roles at each level.
The Players: Producers, Consumers, and Decomposers
Living organisms within a food chain generally fall into three broad categories: Producers, Consumers, and Decomposers.
Producers are organisms that harness the sun’s energy to make their own food. These include green plants, algae, cyanobacteria, and a few other bacteria. But for our gardening purposes, we're mostly focused on green plants. Through photosynthesis, plants convert sunlight, carbon dioxide, and water into sugar (their food) and oxygen. These sugars get used for growth, cellular maintenance, or are stored for later use. That energy remains within the various parts of the plant—leaves, stems, roots, seeds—forming the base of the food chain.
Consumers are the organisms that eat other organisms to gain energy and nutrients. These could be herbivores (plant-eaters), carnivores (meat-eaters), or omnivores (both).
Decomposers—nature’s recyclers—break down what’s left: dead organisms that weren’t eaten, fallen leaves, and waste products. They return nutrients to the soil, completing the cycle.
A Simplified Food Chain
Sun → Plants (Producers) → Herbivores (Primary Consumers) → Carnivores (Secondary/Tertiary Consumers) → Decomposers
It all starts with the sun. Plants—our producers—use photosynthesis to convert sunlight into sugars, storing that energy in their leaves, stems, roots, and seeds. This is the foundation of the food chain. Without plants capturing solar energy, nothing else functions.
Herbivores, or primary consumers, eat those plants. Then carnivores eat the herbivores—and sometimes each other—moving that energy up the chain. But only about 10% of the energy from one level is passed to the next. The rest—roughly 90%—is lost through the organism’s daily life: some is used for movement, growth, and reproduction, some is lost as heat, and some is simply undigested and excreted. That’s why ecosystems need a large base of plants to support fewer herbivores, and even fewer predators at the top.
Decomposers—fungi, bacteria, and some insects—round out the system by breaking down dead matter and returning nutrients to the soil. That feeds the plants, and the whole cycle starts again.
In a balanced ecosystem, each level eats just enough of the one below it to survive without destroying it. Herbivores chew some leaves, but don’t wipe out entire plants. Carnivores control herbivore populations, but don’t eliminate them. And the amount of life at each level is limited by how much energy and nutrition is available below. Disrupt one tier—especially the plant base—and the whole system starts to wobble.
What Happens When the Chain Breaks?
1. Plants That Don't Feed Herbivores
What happens when we introduce plants that nothing eats? That’s essentially what we’re doing when we use non-native plants that haven’t co-evolved with local wildlife and offer little to no food to local herbivores or pollinators—no foliage for caterpillars or mammals, no pollen for specialist bees.
In the best-case scenario, these plants simply reduce the total available nutrition in the food chain. In the worst-case scenario, we’re talking about invasive species—plants that outcompete native vegetation and offer little to no nutritional value. The result? A drop in both the quantity and diversity of organisms the ecosystem can support.
Food Chain Without Supportive Plants:
Sun → Plants (Producers) → Decomposers
2. Removing Predators from the Top
The opposite issue occurs when we remove predators from the top of the chain. This is a key reason why deer populations are so out of control in many suburban areas, especially on the East Coast. Historically, deer had predators—wolves, coyotes, bears, and cougars. Today, we don't tolerate these predators in our neighborhoods or green spaces.
The result is predictable: more deer reproducing unchecked, which leads to more browsing pressure on vegetation. Add in habitat loss from development, and of course they’re eating your flowers and shrubs. What else are they supposed to do?
Food Chain Without Carnivores:
Sun → Plants (Producers) → Herbivores (Consumers) → Decomposers
So What Can We Do as Gardeners?
Let’s bring this back to our gardens. Understanding how the food web works can help us make better choices that support—not hinder—local ecosystems.
Holes in Your Leaves Are a Good Thing
I'm not suggesting we want to see our plants eaten down to the ground. That’s a sign of system imbalance. But some chewing? A few holes? That’s a sign of life. It means your plants are feeding someone—likely a caterpillar or beetle larva that will become food for birds or turn into a butterfly. That flawless double-petaled camellia with pristine leaves may look picture-perfect, but to wildlife (and pollinators who tend to avoid double petaled flowers), it might as well be plastic.
Be Thoughtful with Non-Native Plants
Many traditional ornamental plants aren’t native and don’t contribute much ecologically. If they’re well-behaved and non-invasive, adding a few is fine—especially if they connect you to your gardening history (grandma’s roses or peonies) or make your garden more recognizable to your neighbors.. Just be honest about the trade-off: you’re prioritizing ornamental or sentimental value over ecological function. Your garden might not use a lot of water. But that doesn’t mean it is a force for good in the local environment. A few non-native plants can be okay, but invasive species are where we need to draw the line. They displace native plants and starve the food web.
A Bit of Sympathy for the Deer
Believe me, I get the frustration. But let’s zoom out: we’ve taken away their predators (which has increased their population), we’ve encroached on their territory, and now we’re annoyed that they’re eating plants in our gardens? They’re not doing this out of spite—they’re just trying to survive. Expecting them to control their population on their own is wishful thinking. In addition to fencing, sprays, and smart plant selection, we should be more flexible in the amount of deer browsing that we tolerate and expect.
Feed the Decomposers: Don’t be Too Neat and Tidy
Similar to the human gut biome, a rich soil microbiome is critical for ecosystem function. These organisms require a consistent supply of decaying organic matter. Therefore, rather than undertaking meticulous spring clean-up, consider leaving dead plant material in place. Fallen branches can be cut and left to decompose, or combined into a brush pile in a less prominent area. Try leaving the leaves to decompose in place or using leaves as mulch. These actions collectively promote a healthy soil microbiome, facilitating nutrient cycling and ultimately leading to more vigorous plant growth.
