DISCUSSION : FORESTS, RESERVOIRS, AND STREAM FLOW 467 
periods at any time of the year, more effectively than do the soil and mr. Chitten- 
crops of deforested areas similarly situated. It acts as a reservoir,  4e 
moderating the run-off from showers and mitigating the severity of 
freshets, and promotes uniformity of flow at such periods.” 
From the further study which the writer has made since the 
appearance of the paper, and from the various arguments that have 
been presented by those discussing it, he is more than ever convinced 
that the above statement errs on the side of liberality to the con- 
ventional forestry theory. So accustomed have we become to the idea 
that the forest bed possesses a vastly greater absorptive capacity for 
rain water than does the soil in the open country that we rarely stop to 
» verify these impressions by reference to the facts. Plowing and tilling 
are great agencies in promoting the porosity and absorptive power of 
the upper layer of the soil. Quite as important is the constant putting 
forth of plant roots and their annual or periodic decay as crops are 
harvested or changed. To a great extent do these processes of cultiva- 
tion open up interstices in the soil that did not exist before, and thus 
increase its absorptive capacity. Mr. Pinchot has cited an example 
of this in the cultivation of treeless tracts in the Red River Valley. 
There may also be cited the example of the Minnesota River water- 
shed and that of Devil’s Lake, in North Dakota, where a portion of the 
water which once flowed rapidly away into the streams is now absorbed 
in the soil and either given out in the growing crops or conveyed to 
the streams later through underground seepage. 
In the forest, on the other hand, the soil is not soft, as we are 
commonly led to suppose, unless it be in wet or swampy situations. 
Under the thin covering of deciduous trees, particularly in the hilly 
districts of New England and the Middle States, the soil is clean and 
sharp, unmixed with mould, hard and firm. The writer has verified 
this fact hundreds of times in actual work. In the evergreen forests 
of the Rocky Mountains the thin covering of needles has almost no 
retentive capacity. The ground is often distinctly visible and the 
shoes of horses passing over it cut into the clean dirt. In the figures 
shown on Plate XX XVII the forest soil has nothing like the retentive 
capacity of the soil shown in the open country picture. In the one 
ease it is hard and compact, the covering very thin; in the other, 
mountain grasses and other plants are growing, the soil is loose and 
much worked up by burrowing animals, and yields readily to pressure. 
As between. these two typical areas, the open country soil, although 
never cultivated, has the greater absorptive or retentive capacity. 
Particular stress is here laid upon this fact of the naturally com- 
pact condition of a forest soil, because of the prevalent opinion to the 
contrary. Mr. Leighton says that the forest mulch keeps the ground 
“in a condition that is always equivalent to that of a newly plowed 
field. No one who has ever scratched away the mulch cover in a 
