113 
Reference may be made to a paper, " The Relation of Forests to Stream 
Flow," by James "W. Tourney, in the Year Book of the U.S. Department of Agri- 
culture for 1903, p. 279. 
(c) The Relation of Forests and Snow. 
This subject is not of such importance to Australia as to many other 
countries, but we have extensive areas over which snow falls more or less, while we 
have heavy falls in south-eastern New South Wales, north-eastern Victoria, and 
in Tasmania. 
In Bulletin No. 55 of the Agricultural Experiment Station of the Agricul- 
tural College of Colorado, under the subject of " Forests and Snow," Mr. L. G. 
Carpenter arrives at the following conclusions on the subject : 
CONCLUSIONS. 
1. The mountain streams in the early irrigation season are largely supplied by melting snow. 
2. There is a marked [diurnal fluctuation, greater with high water than with low, due to liho 
daily variation in the rate of melting. 
3. The stream at high water may be one-half greater than at low water on the same day. 
4. Cloudy weather in the mountains, protecting the snow from the radiation of the sun, causes the 
fluctuation to disappear and the flow to decrease. 
5. This decrease is so great that the cloudiness associated with continued rain usually more than 
counterbalances the gain from the rain. 
6. The loss of snow by evaporation is considerable, especially when exposed to winds. 
7. Snow remains in the timber and in protected spots much longer than where exposed. 
8. This is due not so much to drifting as to shelter from the radiation afforded by the forest cover. 
9. Hence, the greater amount of forest cover, the less violent the daily fluctuation, the more uniform 
the flow throughout the day and throughout the season, and the later the stream maintains 
its flow. 
10. The loss of the forest cover means more violent fluctuation during the day, greater difficulty in 
regulating the head-gates and keeping a uniform flaw in ditches, and hence an additional 
difficulty in the economic distribution of water. Also, the water runs off sooner, hence the 
streams drop earlier in the summer, and, on account of the lessening of the springs, the smaller 
is the winter flow. 
11. The preservation of the forest is an absolute necessity for the interest of irrigated agriculture. 
(d) To prevent evaporation of water. 
In the Journal of the Royal Agricultural Society, New Series, vol. ii, page, 
110, there is a statement by Mr. R. Orlebar, of Wellingborough, on the advantage 
of planting trees around ponds, in which he says : 
It is astonishing what effect a little shade has in checking evaporation. A pond that is well shaded 
will hold water for weeks after one of equal dimensions, but lacking shade, will become dry.* 
This is a matter of considerable importance to us, as in most parts of the 
country the conservation of water is the first consideration. Officers having control 
of roads are usually very particular, where the road is at all damp, to cut down the 
trees by the side of it, in order that the sun and wind may play upon the road and 
dry it up. It is quite true that trees by the side of water absorb some of it during 
the process of growth and emit it into the atmosphere by the process of transpiration, 
* Brown, oji. cit., p. 55. 
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