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Trees and Streams
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Hyak swims strongly up the South Fork. Although she has encountered many changes in the river, the human activity which has probably changed the river the most is further upstream still. The river is showing these changes down its entire length. Large loads of new gravel and silt have been washed into the river. The old riverbed has become so full of dirt, there's not always room for the water. Farms and homes along the river have been flooded again and again.
Look again at your "Skokomish Watershed and Land Use Map". What is the main human activity taking place along the small streams on the west side of the map, streams which feed the South Fork?
Clearcutting is the most common practice in logging today. In clearcutting, all trees are removed from the harvested area. Could clearcutting be causing problems like these? The following experiment will help you find out!
Directions: Fill two paint trays with dirt or sand. Mold the dirt into two identical landscapes. Plant "trees" in one by pushing sticks, leaves and grass into the dirt. Label this tray "Plot A". Leave the second tray barren, and label it, "Plot B".
- Predict what will happen to your two landscapes when the winter rains come. Which plot will probably experience more erosion?
Use a watering can to make it rain on your two watersheds.
- What differences (if any) did you see in your landscapes after the rain?
- From the results of your experiment, what might be the effect on soil erosion in a region if all the trees are cleared?
- Your experimental watersheds had relatively gentle slopes. How might slopes lke the one below be differently affected?
- This river may also be carrying a heavy load of silt and gravel. What effect might this silt have on the nest Hyak will soon be building -- and on her baby fish?
- Trees are important to salmon in many ways. You learned about one way in the experiment, "Warming It Up". What was it?
- You learned about a second way trees are important to salmon in this experiment, "Trees and Streams". What was that?
 Here's one more way. Trees drop leaves and twigs into the water and along the stream banks. This makes food for water insects. Although spawning salmon like Hyak aren't interested in insects, her babies will be. In fact, they will eat large numbers of insects while they are in the river.
- What could removal of trees do to the supply of food for baby salmon?
Timber harvested in Washington is used to build homes, to make paper, and to sell to other countries. Many people in Washington make their living cutting trees, milling lumber, making paper products, or in building with the wood available in the Pacific Northwest.
- What are two items that you use which come from trees growing in places like the Skokomish watershed?
- Cutting fewer trees alongside streams and in steep watersheds would improve stream water quality for salmon. What changes in your family's lifestyle would decease the demand to cut those forests?
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