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Extension to PLT Activity 24
Nature’s Recyclers
Lesson Summary
The original version of Nature’s Recyclers teaches students
about the process of decomposition by observing pill bug,
sow bug, or earthworm behavior.
This extension to Nature’s Recyclers places emphasis on the
importance of decomposers in a healthy forest ecosystem. It
draws students’ attention to decomposing organisms that are
not often noticed, such as fungi and bacteria.
d. What are other examples of decomposing organisms?
Decomposers are abundant in our ecosystem and likely
outnumber all other groups of organisms in diversity and
quantity. But many of these organisms are unfamiliar to us
because they are either microscopic (Figure 8) or hidden
deep in the soil or within plants and animals. These may
include insects such as beetle grubs or fly maggots,
numerous fungi, and countless bacteria.
Illustration: Geetha S. Iyer
Doing the Activity
1. Read the original Nature’s Recyclers on page 108 of the PLT
Activity Guide, including the Background Information, Getting
Ready, and Doing the Activity sections.
2. This extension builds on the wrap-up question in step 9 of
Doing the Activity, “How might sow or pill bugs be important
to a forest ecosystem?” Make sure to touch upon the
following questions in an expanded discussion on the role of
decomposers in an ecosystem.
a. What is an ecosystem service?
An ecosystem service is a vital function that some
organisms in the ecosystem provide for the benefit of all the
others. For instance, plants produce oxygen that other
animals need to survive. Decomposition is another
ecosystem service that organisms such as pill bugs and sow
bugs provide. If they didn’t exist, dead matter would pile up
on the forest floor, and all the nutrients locked within that
matter would not be recycled back into the ecosystem.
b. Do decomposers obtain their food by killing organisms?
No, most decomposers are not responsible for killing an
organism. For instance, decomposers that specialize on dead
plant matter usually don’t eat living plants—they are not
herbivores. Similarly, decomposers don’t hunt down living
animals like carnivores do; they consume and break down
dead animal tissues instead.
Figure 8. Tiny titans: Most decomposing organisms are
microscopic, but they have an immense impact on ecosystem
health. Clockwise from top left: nematode, amoeba, filaments of a
fungus, and soil bacteria.
3. Wrap up the discussion by telling students that while
decomposers such as insects and fungi do not kill organisms,
other insects and fungi certainly can. Ask students to
contemplate whether organisms that could damage, disease,
or kill trees are essentially good or bad for the ecosystem.
Can they be both? Impress upon students the important roles
of all organisms in a healthy ecosystem—when some
organisms die, others profit. This process is cyclic. For
instance, the nutrients released by decomposition of an old
tree may favor the growth of seeds that the tree produced
before it died.
c. What sorts of waste can students imagine finding in a forest?
Leaf litter; pieces of fallen bark; dead trees; dead animals;
cast-off skins of animals that molt, such as snakes or cicadas;
empty egg shells; animal droppings; and fallen fruit are
among the dead matter that may be found in a forest.
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What Is a Healthy Forest | Section 1 | Forests as Ecosystems