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00066C . J . - , ',I. Leaf (1) points out that water yield increases are far less in the case of clearcutting when compared to patchcutting. Lenf 0) also points out that when canopy density is reduced 50 percent by selective cutting on spruce-fir forests on northerly aspects, water yields may actually be decreased. Neil (2) reports that, according to Rodda (37), the influence of forests on the runoff may still be a matter of debate. He further points out that in case of large scale clearcuts, water yield may be reduced in certain conditions. (7) Erosion Not much emphasis was placed on the effect of timber cutting on ero- sion. Erosion and sedimentation occur in the early years for the most part on most of the watersheds where clearcutting practices have occurred 03, 14, 23). On some watersheds, water quality. was a problem but with proper cutting practices thi.s can be reduced. ~. , V. CONCLUS IONS From this literature review, the following conclusions can be drawn. -; 1. Clearcutting or patchcutting results in an increase in snow accumu- lation in cut areas. Snow accumulations are greater in case of patchcutting compared to clearcutting. 2. Patchcutting results in significant redistribution of snow -- more snow in openings and less in uncut areas. However, the total change in water content on headwater basin may not change significantly. 3. Decrease in interception losses due to cutting may almost be compen- sated by an increase in evaporation losses from the snow surface. ., ~~ . j :j . ! ."j ~.. f r-j H n '.'1 4. Wind plays in important role in transportation and distribution of snow, and in evaporation and sublimation losses. r 5. Orientation of slope is an important consideration in timber cut- ting. North-facing slopes seem .to be more favorable than south facing in producing water. 6. Soil moisture deficits decrease slowly as the reforestation takes place. increase water yield and vice-versa. due to deforestation and increase Decreases in soil moisture deficit 7. It is the opinion of most of the authors that clearcutting or patch- cutting results in increases in water yield. The increases are greater in case of patchcutting compared to clearcutting. 8. Most of the increased runoff occurs during the spring snowmelt season and no signi ficant change occurs on the recession part of the hydro- graph. For instance, one author reported that about 17% of the increased w-ater yield occurred during late SlDlll11er months from a study area on a north facing slope. -4-