What if there were no decomposers?

Explore the idea

• Established fact

  Decomposers break down dead things and give plants food back.

  Decomposers break down dead plants and animals and return nutrients such as nitrogen, phosphorus and calcium to the soil for plants (National Geographic).

  Decomposers, usually bacteria or fungi, recycle organic material back into the biotic part of the ecosystem (OpenStax), releasing nitrogen, phosphorus and calcium compounds for producers (National Geographic).

• An idea scientists discuss

  The world with no helpers is pretend. We imagine what might happen.

  A world with no decomposers is imagined. What might happen in it is an idea built from what scientists know about how dead material is recycled.

  No real ecosystem lacks decomposers entirely; the outcomes here are ideas extrapolated from documented roles and from partial cases such as soils without earthworms.

• Established fact

  Decomposers break down dead leaves, wood and dead plants and animals.

  Decomposers feed on dead leaves, wood, dead plants and animals, and animal droppings, and National Geographic calls them Earth's cleanup crew.

  Decomposers feed on leaf litter, wood, carcasses and feces, breaking dead organisms into simpler inorganic materials that make nutrients available to producers (National Geographic).

• Established fact

  Without decomposers, dead things would pile up.

  National Geographic explains that without decomposers, dead leaves, dead insects and dead animals would pile up everywhere.

  National Geographic states that without decomposers, dead leaves, insects and animals would pile up everywhere.

• Established fact

  In one big forest, fungi break down the fallen wood.

  At Muir Woods, the National Park Service says that without the fungi that break down its dead wood, the forest would be nothing but a wood pile.

  The National Park Service describes saprotrophic fungi as Muir Woods' decomposers; without them, dead wood, leaves and other organic matter would accumulate on the forest floor.

• An idea scientists discuss

  In the pretend forest, the leaf pile might get very deep.

  In the pretend forest, fallen leaves and wood might build up every year, covering the ground where new seeds would try to grow.

  In the imagined forest, litter might accumulate indefinitely; whether that might smother seedlings or change how water soaks in is a reasonable idea, not a measured result.

• Established fact

  Decomposers put back what plants need to grow.

  Decomposers break dead material into water, carbon dioxide, and simple materials with nitrogen, phosphorus and calcium, which plants need to grow.

  Decomposers break complex organic material into water, carbon dioxide and simple compounds of nitrogen, phosphorus and calcium, returning them to soil or water for producers (National Geographic).

• Established fact

  Some forests need their fallen leaves to turn into soil.

  In redwood forests, decomposers turn fallen leaves into a rich, dark layer of soil, recycling nutrients that would otherwise be unavailable, says the National Park Service.

  Redwood forests depend on rapid nutrient cycling in the topsoil that decomposers build from shed leaves; the subsoil beneath is typically weathered and nutrient-poor (National Park Service).

• Established fact

  Breaking down old plants gives soil lots of plant food.

  Oregon State University Extension says each ton of soil organic matter broken down by microbes may release as much as 220 pounds of nitrogen in a form plants can use.

  Each ton of soil organic matter decomposed by microbes may yield as much as 220 pounds of nitrogen, 33 pounds of phosphorus and 33 pounds of sulfur in plant-available forms (Oregon State University Extension).

• An idea scientists discuss

  In the pretend world, plants might grow more slowly.

  In the pretend world, plants might grow more slowly as the soil ran short of nutrients, and animals that eat plants might find less food.

  With mineralization halted, plant productivity might decline as available nutrients were used up, with knock-on effects up the food web; the pace might vary greatly between ecosystems.

• Established fact

  Bacteria are the most common helpers in compost.

  Bacteria make up 80 to 90 percent of the billions of tiny living things found in a gram of compost.

  Bacteria make up 80 to 90 percent of the billions of microorganisms typically found in a gram of compost and are responsible for most of its decomposition and heat (Cornell).

• Established fact

  Millipedes and slugs chew dead plants into small bits.

  Millipedes, sow bugs, snails and slugs shred dead plants, which gives fungi and bacteria more surface to work on.

  Millipedes, sow bugs, snails and slugs shred plant material, creating more surface area for fungi, bacteria and actinomycetes (Cornell).

• Established fact

  When people brought earthworms to new land, good soil formed.

  Some land in the Netherlands, won back from the sea, had no earthworms, and good topsoil did not form. After earthworms were introduced, dark topsoil formed and crops grew much better.

  In Dutch soils reclaimed from the sea that lacked earthworms, topsoil with reasonable organic matter did not form; after a government campaign introduced earthworms, a dark topsoil formed and crop growth increased substantially (Penn State Extension).

• An idea scientists discuss

  Without the helpers, the forest might stop making new soil.

  If the whole team vanished, the pretend forest might stop making new soil, just as the Dutch fields did without their earthworms.

  The Dutch case removed one group; removing every decomposer might halt soil formation and nutrient release together, which is why this world is imagined rather than modeled.