THE QUADRAT METHOD. 



427 



plants in flower or fruit by a vertical line. In forest quadrats, seedlings are 

 usually indicated by a small letter and mature individuals by a capital. In 

 charting seasonal aspects, the rule is to indicate only the characteristic species, 

 i. e., those that flower at the time concerned. 



The chief use of chart quadrats is for the comparison of different examples 

 of the same community, or adjacent zones or stages of a sere. They are indis- 

 pensable for the method of inference by which scattered stages are combined 

 to show the course and sequence of a sere. Since permanent quadrats give 

 all the values of simple chart quadrats, and many others besides, the chart 

 quadrat should be used only when a single visit to a region makes the perma- 

 nent quadrat unavailable. 



Fig. 46. — Quadrat showing reproduction in a complete bum, Long's Peak, Colorado. 



Permanent quadrat. — ^In exact successional research it is imperative to be 

 able to follow the course of development in detail from year to year, and espe- 

 cially from one minor sun-spot cycle to another. This is possible only by 

 means of quadrats whose location and limits are fixed so that they can be 

 relocated and charted from season to season, year to year, or from one period 

 to another. These are termed permanent quadrats (Clements, 1905:170; 

 1907 : 208), since they make it possible to secure a complete record of all 

 successional changes in the area studied. Naturally, they are always recorded 



