Decomposition:
Shredders and Decomposers

6th grade fall unit

revised October 25, 2007

Unit goals

While most study in the natural world tends to focus on the living, the return of once-living material back to the ecosystem in a useable form is equally deserving of our attention. In this unit, the students will learn to recognize decomposers and shredders and their important role in the nutrient cycle, further understand the interdependent relationship between the living and non-living components of nature, and explore these concepts in relationship to their own lives.

-- Summary Box --

Before your visit, please review with your students ...

Distinguish between producers, consumers, and decomposers
The non-living parts of cycles in natures (air, water, sunlight, rocks)
Review a food chain/web, either theoretical or observed, that incorporates all the components of a nutrient cycle.

At River Bend ... (a worksheet packet will be used - sample)

Meet at the Trailside Center.
During the introduction we will review the above material
Students will be divided into four groups and then work in pairs within the groups.
Students will:
- Identify sources of organic material
- Specify the sources of inorganic elements
- Examine four different groups of shredders and decomposers and their roles:
  - Fungi
  - Earthworms, slugs, etc.
  - Arthropods
  - Moss & Lichen
Students will follow the scientific method and record detailed observations to share with the group during the conclusion
In the closing we will ...
- inquire about students' results
- remind the students of their next visit
- talk of upcoming events at River Bend
- invite the students to return on their own with family and friends

Back in the classroom ...

Compare decomposition principles of the natural world to how waste is dealt with in their own lives
Identify components of our waste
Describe current avenues for waste management or disposal
Contemplate various options based on appropriate criteria

What is organic material?

Organic material is matter that either is or once was a part of a living plant or animal. Fur, feathers, bones, meat, blood, scat, leaves, bark, wood, are all examples of organic matter.

What is inorganic material?

Matter that is not or never been living tissue. Rocks, water, sunlight, air are best examples. While not living, all are important in the nutrient cycle.

What is the the nutrient cycle?

Organic material is always being used and reused, over and over again. Taken from the soil by plants, called producers, it is then passed on to herbivore consumers, which in turn are eaten by carnivore secondary consumers. The organic material from each, upon dying, are made available for the plants to use again by the decomposers. In many ways, the nutrient cycle resembles a food chain, since, in fact, any complete food chain you can imagine is actually a nutrient cycle as well.

What are some decomposers?

There are many, many types of decomposers that take dead plants and animals and break them down into nutrients in the soil so that plants can use them to grow. Frankly, almost all creatures, including ourselves, are decomposers in some way since we pass food through our systems and create decomposing waste. But there are many forms of life that break down dead matter directly and are the primary factors of decomposition. Here are just a few you will find at River Bend:

Fungi

earthworms, snails, slugs, and other "slimy" crawlers

various arthropods

lichens and moss

What will we do at River Bend?

Your field experience at River Bend will basically be one of exploration and investigation. With your partner, you'll use the scientific method and observation skills to learn more about decomposers and shredders:

You'll scour rotting logs and the forest floor for decomposers, and note specifics of the individual decomposers and their habitats.

What do we need to remember when we visit River Bend?

Be quiet.
Listen to your leader.
Raise your hand if you have something to say.
Do not pick anything unless given permission.
Stay with your group and on the trail.
Be respectful of nature - and of each other!

Some suggested pre- or post-visit activities

Send us your ideas here!

Create an experiment using several different containers with similar waste material. Add different decomposers (such as worms) to each sample, and none to one of the samples, and record the changes over time.
Discuss what happens to our own waste. Where does it go? Is it still a part of the nutrient cycle? What implications do your findings have on our society? On our ecosystem?

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Interesting links

The following links contain some interesting information on decomposition or soil: Send us your ideas (and broken links) here!

MN DNR's Conservation Volunteer piece on the subject
http://www.dnr.state.mn.us/young_naturalists/soil/index.html

An extensive site on fungi
http://botit.botany.wisc.edu/toms_fungi/

Creating a compost bin experiment
http://www.wpcog.dst.nc.us/recycling/rotten.htm

Worm Watch home page
http://www.nrri.umn.edu/worms/

Fun with fungi
http://namyco.org/educ/prj.htm and
http://namyco.org/educ/k-12.htm

A page on lichens
http://bionet.informatik.uni-oldenburg.de/aerodata/lichenes/einfo.htm

Decomposition: Shredders and Decomposers