Introduction & Teacher Background
A child's exposure to death is often shaped by television, or the passing of a friend, relative or pet. Death is often associated with human violence and personal loss in popular culture, and is thought of as "bad." In the processes of nature death is essential. There is no life without the death of something else. Wolves eat deer, deer eat plants, plants eat soil - and soil is made from dead plants and animals. It is a constant cycle and recycle process, and all of life depends on it.
In the Waterton glacier International Peace park, these processes are left to happen the way they always have. Our excitement at seeing a grizzly bear can be directly attributed to the cycles of life and death. These cycles are the fuel for a vast and beautiful system, but we seldom appreciate the "story behind the scenery"- in part because of our discomfort with the processes of death and decomposition. This Unit is about helping us, and our students, see that rotting smells, instead of "stinking," are rich odors of life renewing itself.
This Unit is an opportunity for students to directly experience the processes of decomposition and soil formation. It can be greatly enhanced with the use of two excellent resources: 1. "The Puzzle of the Rotting Log" (a video by the Missouri Botanical Gardens, and 2. Lifetimes, a book by B. Mellonie and R. Ingpen.
Plants get their nutrients from the soil. Many decomposers get their nutrients from other plants and animals that are already dead. Decomposition is the process of decay. It is a side effect of digestion of dead material. Decomposers (fungi, bacteria, insects, worms, etc.) use dead material for food. During decomposition, the dead material is broken down into small pieces. When humans eat food, enzymes digest our food. Likewise, decomposers secrete enzymes into dead material to do their digestion.
Bacteria are microscopic, single celled organisms which are found by the millions nearly everywhere on planet earth. Some bacteria cause diseases, but most are beneficial decomposers, returning valuable nutrients to the soil. In norhtern climates such as ours, decomposing bacteria do not have a long enough growing season to do the bulk of decomposition. Here, and in WGIPP, the bulk of those processes is done by fungi.
Fungi are plants without the normal green pigment (chlorophyll) of other plants. They cannot make their own food, so they feed on dead plants and animals. They produce microscopic strands, like tiny roots, which secrete digestive enzymes. Some of the wet, old growth forests of WGIPP have literally tons of these strands per acre of soil. When the fungi reproduce, they form the familiar mushrooms we see whenver it is wet.
Some scientists have estimated that as many as 20,000 species of decomposers can live in a single rotting log! The breakdown of dead trees is started byt the larger animals (woodpeckers, etc.) and is finished by the smallest (fungi and bacteria). Between, there are chipmunks, mice, millipedes, centipedes, mites, ants, and thousands of other insects.
Some of the questions students will address in the unit are: What organisms live in a rotting log? Which are decomposers? What makes a log good habitat for decomposers? How do fungi eat? How is their eating different from ours? Why don't some things decompose, or decompose very slowly? How do decomposers help all plants and animals?