QUADRATS 167 
It is obvious that the above outline is faulty inasmuch as it takes no 
account of the height and width of the individuals. This is a serious 
defect, and it constitutes one of the many reasons why the list quadrat should 
be replaced by the chart quadrat. The prairie formation affords an un- 
usually striking illustration of this. A single quadrat may be filled by ten 
plants of Psoralea floribunda, and at the same time contain 22,000 plants of 
Festuca octofora. Yet the former is conspicuous and controlling; the latter 
plays an altogether insignificant role. This difference is readily shown by 
comparing a plant of each. The one is 3 x 3 feet, the other 3 x % inch. 
Such figures furnish a valuable check upon mere number, but make the 
brief, graphic designation of abundance difficult. An attempt has been 
nade to solve this problem by roughly determining the space occupied by 
the plant, by means of the formula, height (2A?) X abundance. This 
would give Psoralea a value of 210, and Festuca one of 1.6, which much 
more nearly represents their real importance in the formation. Abundance 
or numerical value is a floristic concept entirely, and has little place in 
ecology unless checked in the way indicated. The whole problem, ecologi- 
cally, depends upon an intimate knowledge of competition, and its solution 
in consequence is at present impossible. , 
The Chart Quadrat 
207. Description and use. The detailed labor required in mapping makes 
it advisable to use the meter quadrat. An additional reason of much impor- 
tance is furnished by the desirability of securing a detail photograph of the 
quadrat. This is impossible with field cameras, which should not exceed 
6% x 8% inches, and are indeed most serviceable in the 4 x 5 size, if the 
area be larger. In open formations, the major quadrat of 2 meters can be 
used if necessary, but this is very rarely the case. Forest quadrats of ten 
meters square are easily charted, but detail photographs can not be made of 
them. Larger quadrats are impracticable; they can be counted but not 
mapped to advantage. The location of the chart quadrat must be decided 
by the structure to be studied. Its greatest service is in connection with 
zones and societies of the same formation, which can be easily compared 
in the chart form. In fact, the chart quadrat may well be regarded 
as the fundamental method for inquiry into zonation and alternation. It is 
an important aid in delimiting areas from the contiguous formations, and in 
determining the relationships of mixed formations. It is also used to record 
the character of the different aspects, but this is done more satisfactorily by 
the permanent quadrat. 
