174 THE FORMATION 
register the exact course of the succession, denuded ones can merely furnish 
facts as to the probable courses of stages not now in evidence. 
214. Methods of denuding and recording. Permanent quadrats may be 
denuded at any time during the time they are under observation. The best 
results, however, are to be obtained by establishing the two side by side, or at 
least close together. In this way, they are mutually supplementary, and fur- 
nish the most evidence possible with regard to the procedure of invasion and 
competition. Another advantage is found in that the same observations of 
climatic factors will do for both, though water-content and soil temperatures 
Fig. 54. Denuded quadrat; this is the quadrat shown in figure 53; 
photographed September 7, 1904. 
are necessarily different. A quadrat which is to be denuded is first mapped, 
photographed, and labeled exactly like a permanent quadrat. The vegeta- 
tion is then destroyed. This is usually done by removal, though it may also 
be burnt, destroyed by flooding, or in some other manner. The method will 
depend upon the use which the quadrat is to serve. If it is to throw light 
upon the vegetation of an area in which denudation has affected the surface 
alone, the aerial parts only are removed by paring the surface with a spade. 
When the disturbance is to be more profound, the upper seed-bearing layer 
is removed, and the underground parts dug up. ‘In the interpretation of a 
