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 fioribunda, and at the same time contain 22,000 plants of 

 Festuca octoflora. 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 

 made to solve this problem by roughly determining the space occupied by 

 the plant, by means of the formula, height { ir R^) 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 

 63^ X 8j4 inches, and are indeed most serviceable in the 4x5 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 biit 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. 



