36 THE STUDY OF PLANT COMMUNITIES * Chapter 111 



of sampling by the use of plots is commonly called the quadrat 

 method. The use of the sample plot is by no means restricted to 

 ecology, but its application in the sampling of natural vegetation 

 has led to methods peculiarly adapted to the ecologist's needs. The 

 quadrat has almost unlimited applications and has been used in a 

 great variety of ways. 



Kinds of Quadrats.— The list-count quadrat is probably most 

 commonly used. With this the species are recorded and their num- 



FlG. 11. A small quadrat laid out with meter sticks, which are pinned at 

 corners. Ready for list-count. This is a permanent quadrat that can be relo- 

 cated by paint markings on boulders. At Glacier Bay, Alaska, for the study 

 of early development of vegetation on raw morainic soil. 75 Ice covered this 

 area thirty-seven years before picture was taken.— Photo by W. S. Cooper. 



bers determined by count. This method is subject to many mod- 

 ifications depending upon circumstances. For trees, the individual 

 diameters might be recorded and later used for segregating size 

 classes, or perhaps for computing basal area (indicative of dom- 

 inance) for species. Bunch grasses, too, are often measured across 

 the base to obtain a basal area figure, which, combined with the 

 count, will give a better expression of the relative importance of 

 species. With herbs it is sometimes desirable to have additional in- 

 formation on the weight of tops, which must, therefore, be re- 

 moved for each species. In any event, the species are listed and 

 tabulated by number, weight, or size. 

 A chart quadrat is a more detailed record of the individuals 



