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<br /> <br />0028\;::: <br /> <br />. <br /> <br />. <br /> <br />same efficiency as snow traps. Wind direction during snowfall and tree <br /> <br /> <br />heights also influence size and orientation of efficient openings. Selective <br /> <br /> <br />cutting creates a pattern of openings which traps more snow than an uncut <br /> <br /> <br />forest and clearcutting in blocks or strips can be planned to be even more <br /> <br />effective. Openings between one-half to two tree heights across will hold <br />snow late in the season. Shape and orientation of openings to sun, wind, <br /> <br />and cold air drainage are important. Recent advances in measurement of <br /> <br />energy balance and other physical factors are speeding understanding of <br />snowmelt phenomena. <br /> <br />Precipitation.--Fifty years ago there was a hot debate over whether, <br /> <br />and if so, how forest cover increased precipitation. There was no way to prove <br /> <br />the arguments of either side. There is now a large and impressive amount <br /> <br />of theory to indicate that forests can have no effect on precipitation over <br /> <br /> <br />large areas. This has been extremely convincing even though there is still <br /> <br /> <br />no real proof and there is abundant evidence that meteorological theories <br /> <br /> <br />about precipitation are not indisputable. <br />There is agreement that forests along the sea coast and on mountain <br /> <br />tops capture fog particles and condense water vapors on their leaves. The <br /> <br />amount of water reaching the ground and its hydrologic significance have been <br /> <br />studied little. No tests to determine if fog drip or condensation influence <br /> <br />streamflow have been reported. <br /> <br />Erosion.--Since Chittenden's review, the role of plant cover in <br /> <br /> <br />controlling erosion has been generally accepted. He would have little trouble <br /> <br /> <br />finding evidence to show that vegetation is effective in controlling erosion. <br /> <br />- 4 - <br /> <br />