| 4.
Watershed
5. This watershed manipulation was
designed to look at the effects of a commercial (how forests are often cut by
real loggers) whole-tree harvest on nutrient
cycles.
Watershed
5 was whole-tree clear-cut during the autumn of 1983 through the spring of 1984.
All trees larger than 10 cm in diameter were harvested by removal of whole trees
(bole and tops) using a feller-buncher machine (see below) on accessible slopes and chain
saws on steep inaccessible slopes. With limbs removed, trees were removed using
skidders. In this experiment
a buffer was not left surrounding the stream (as was done in Watershed
4). A total of 180 tons per hectare
of biomass was removed from the
watershed.
 |
A feller-buncher used in
the Watershed 5 clear-cut | Clearcutting
northern hardwood forests like Watershed 5 results in:
An increase
in temperature (as much as 6 degrees C) at the soil surface and in streams - unless
streamside buffers of trees are left around the streams. Many fish, insects, algae,
and other aquatic organisms are sensitive to temperature. An
increase in the moisture content of the soil. Decomposers
that live in the soil can be affected by soil moisture content.  |
Watershed 5 |
A
maximum increase in streamflow of approximately 40 percent, and an increase in
summer peak flows averaging 20 percent. - An
earlier snowmelt runoff.
- An increase of
nutrients, especially nitrate, in the soil solution - subject to loss by leaching
or uptake by plants and microorganisms. Forest nutrient loss may have negative
effects on plants and trees.
| |