Another effect of the removal of trees is an increase in stream temperatures because of the lack of shade.
There are three different riparian reserve widths: Some activities that are restricted or limited in the riparian reserve include: The placement of large woody debris (LWD) in streams creates pools and side channels.
The pools provide habitat for aquatic organisms while the side channels help alleviate flooding.
Since silviculture is a cyclical process, the numbering of the techniques doesn't denote the order in which these operations should begin or the importance of the step.
Prescribed burning is another method of site preparation, but will not work because the shallow roots of western hemlock would get damaged, hurting the seed sources.
Prescribed burning would also damage the thin bark of both western hemlock and red cedar girdling the trees.
To obtain disturbed mineral soil in the small areas that single tree selection creates manually turning up the soil with hand tools or small tillers is the manual site preparation option.
Natural regeneration may be obtained because of the high numbers of annual seed crops (100,000–1 million/acre).
High numbers of seeds will be needed to reach the desired stocking level.
Western hemlock has a good rate of survival in a wide range of conditions.
If the stand was left alone and the forest naturally created gaps for succession then other species that are less tolerant than the desired tree species of western red cedar and western hemlock could overtake the created gaps.
Single-tree selection will contribute minimally to erosion, still provide habitat for wildlife, be aesthetically pleasing to the eye, and follow the best management practices (BMPs) that are associated with riparian forests.
The last reason for doing a single tree selection is that it spreads out income over longer period of time.
The gap formed in the upper canopy allows enough sunlight to come through the opening and reach saplings at the forest floor.
After 50 to 60 years, the advanced regeneration will grow vigorously after overstory removal (Packee, 1990).