l62 THE FORMATION 



not necessary in reconnaissance, nor do they displace general methods of 

 real value. The use of the latter in even a supplementary way will grad- 

 ually be discontinued, however, as fields become smaller by reason of in- 

 crease in the number of workers, and as the need for precise methods 

 becomes more universally felt. 



The quadrat constitutes the initial concept from which all the methods 

 have grown. In itself, it has given rise to a variety of quadrats applicable 

 to the most fundamental problems of vegetation. From it have come, on 

 the one hand, the migration circle, and on the other, the transect. The 

 latter in turn has yielded the ecotone chart, and the layer chart. All of 

 these are based upon direct and detailed contact with vegetation itself, and 

 permit accurate recording of all the results obtained. 



QUADRATS 



199. Uses. In its simplest form, the quadrat, as the name implies, is 

 merely a square area of varying size marked off in a formation for the pur- 

 pose of obtaining accurate information as to the number and grouping of the 

 plants present. As indicated above, it was first used for determining the 

 abundance of the various species of a formation. This made it possible to 

 ascertain the relative rank of the species of layers and formations, and 

 enabled one for the first time to gain some idea of the minute structure of 

 a bit of vegetation. The results were at once applied to the task of establish- 

 ing a numerical basis for abundance, and of working out a new system of 

 abundance to correspond. The quadrat method was also used to determine 

 the character of seasonal aspects, and to yield a knowledge of the exact 

 differences in diverse areas of the same formation. Incidentally, the deter- 

 minations of abundance were made the basis of an actual census of certain 

 alpine formations. This, while it was extremely interesting to find that a 

 square mile of alpine meadow contained approximately 1,500,000,000 plants, 

 was confessedly destitute of ecological value. The most important applica- 

 tions of the quadrat idea were made by Clements^ in the chart, the perma- 

 nent and the denuded quadrats. The development of these was due to the 

 fact that zones or formations permit of comparison upon floristic as well 

 as physical grounds, and that a detailed record of their structure is necessary 

 for this purpose. Similar comparisons are necessary for the consocies, 

 zones, and patches of the same formation, and the quadrat becomes an in- 

 dispensable means for studying alternation and zonation. For the investi- 



*The Development and .Structure of Vegetation, 84. 1904. 



Thornber, J. J. The Prairiegrass Formation in Region I. Rep. Bot. Surv. Neb., 

 5:29. 1901. 



