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A guided journey · 5 stops

The hidden half of the food web

Follow what happens to everything that is never eaten — which, in a forest, is most of what the plants make.

The route

  1. Detritus
  2. Decomposition
  3. The soil food web
  4. Soil
  5. Nutrient cycling

Every food chain drawn for a classroom runs plant, herbivore, predator. Compile the actual production budgets and that pathway turns out to handle a minority of what plants make in most terrestrial systems — in forests, a small minority.

The rest is never eaten alive. It falls, dies, and is taken apart by organisms that almost never appear in the diagram. This route follows that material: from the moment the leaf lands, through the organisms that dismantle it, into the soil it becomes part of, and out the far side as the nutrients the next plant takes up.

The order goes downwards, and it goes from the visible to the invisible.

  1. Stop 1 of 5. Ecology

    Start with the material nobody counted

    Because the measurement reframes everything after it. The grazing pathway handles a minority of production in most terrestrial systems, and the exception proves the point rather than weakening it: in phytoplankton systems most production genuinely is grazed, because single cells with no structural tissue are a different proposition from a tree. Investing in wood is what makes a forest’s energy go the other way.

    Read DetritusThe food chain everyone learns handles a minority of what a forest actually produces.

  2. Stop 2 of 5. Ecology

    Then the hardest part of the job

    Wood is the extreme case, and the corpus already had this page, so the route uses it rather than repeating it. Lignin is a polymer built to resist exactly this, and the fungi that can dismantle it are doing chemistry almost nothing else manages. Reading it here — after knowing how much material arrives — makes the scale of the problem clear rather than abstract.

    Read DecompositionThe ability to digest wood appears to have been invented once, by fungi, and everything a forest floor does follows from it.

  3. Stop 3 of 5. Ecology

    Meet the organisms actually doing it

    And find that most of them are not eating what they appear to be. A springtail grazing leaf litter is largely consuming the fungus growing through it; a detritivore fragments material and inoculates it rather than digesting much. It also supplies the distinction the route needs: decomposers break molecules, detritivores break lumps, and the second mostly makes the first faster.

    Read The soil food webA springtail grazing leaf litter is mostly eating the fungus growing through it.

  4. Stop 4 of 5. Ecology

    Follow it into the ground

    This is where the material ends up, and where the sprint’s biggest correction sits. Soil is a structure rather than a mixture, built by the organisms living in it — and old soil carbon persists not because it is indestructible but because nothing can reach it. Break the structure and carbon safe for decades becomes available, with nothing about the molecules having changed.

    Read SoilSoil is not a mixture. It is a structure, and the organisms living in it are what build it.

  5. Stop 5 of 5. Ecology

    And end where it runs backwards first

    The route’s payoff. Decomposers are usually described as returning nutrients to plants, and over long enough periods they do — but a microbe decomposing a carbon-rich leaf needs nitrogen to build itself, and takes it from the soil. For months, adding dead plant material can reduce the nitrogen available to plants. The tidy loop everyone is taught runs the other way first.

    Read Nutrient cyclingAdding dead leaves to soil can leave plants with less nitrogen, not more — for months.

Where this leaves you

You end with the thing the food chain leaves out: not a footnote about decomposers, but the pathway most of the energy actually takes, and a set of organisms doing quite specific jobs that popular writing merges.

The stop that stays with you is the last one. Everyone knows decomposition returns nutrients to plants. Almost nobody knows it takes them out first — that adding carbon-rich dead material to soil can leave plants with less nitrogen for months, because the microbes doing the decomposing need nitrogen too, and they are competitors before they are suppliers.

What the route does not settle: what determines whether a litter mixture rots faster or slower than its parts, which is repeatedly observed and genuinely unexplained.

Last reviewed 2026-09-04. All guided journeys