RESEARCH METHODS IN STUDY OF FOREST ENVIRONMENT. 73 
Total-Moisture Determinations. 
The determination of the current-moisture content of the soil at 
a given point is an exceedingly simple matter, and a vast amount of 
such work has been done in connection with agricultural investiga- 
tions and greenhouse experiments ; in fact, so much has been done that 
citations are useless. 
On the other hand, repeated determinations at a given point to 
show changes, minima, etc., immediately introduce complications. 
When a sample has been taken from the ground, it is very difficult to 
fill the space with the same kind of soil as before, and even if this 
were accomplished the new soil would not soon be in a normal mois- 
ture condition. The next sample must, therefore, almost certainly 
be taken a short distance away, and almost invariably this introduces 
a change in composition, such that equal moisture contents in two 
successive samples may not have the same plant value. Usually in 
agricultural soils or well-mixed potting soils, these variations may 
be ignored. Very often in forest soils, however, the changes in 
composition are very abrupt; in fact there is often no such thing 
as uniformity of soil texture, even in a practical sense. The sampling 
of forest soils, moreover, is often difficult owing to the presence of 
rocks which make it impossible to obtain a sample at the desired 
spot, at least with borers of any description. These mechanical diffi- 
culties may usually be overcome by the use of pick and shovel, and in 
careful surveys of the root zones of individual trees or groups such 
methods will undoubtedly have to be resorted to. 
In practice, it is usually impossible to examine a large number of 
soil points with sufficient frequency to show even approximately 
the changes in soil moisture. It is necessary to select, more or less 
arbitrarily, points which seem to represent the average of conditions 
in the plant formation or forest type under study, and to confine the 
effort to showing as accurately as possible all the conditions which 
occur at this point. 
SOIL-WELLS FOR REPRESENTATIVE POINTS. 
In view of what has been said, it appears necessary to make provi- 
sion for establishing some standard conditions under which soil sam- 
ples shall be taken at permanent stations. The ideal method would 
undoubtedly be to show the moisture content of a single sample of 
soil from time to time, and it has been suggested that this might 
be accomplished by the periodic weighing of a standard soil sample 
contained in a porous cup which would be permanently located at 
the soil point. This plan involves a number of technical difficulties, 
and is, moreover, wholly untried. The nearest practical approach 
to the method of a single sample would seem to be in the plan of 
