CHART PLOT 34 1 



be square, rectangular, circular, or of irregular dimensions. 

 The square plot, known to ecologists as the " quadrat," is usually 

 the most convenient. If the sample areas are a quarter of an 

 acre or larger, one or more small square plots about 3 feet or 

 one meter in size are estabhshed within the larger area for 

 detailed mapping of the vegetation. The information afforded 

 by these small plots supplements the more general data relating 

 to the larger area. The main plot is usually blocked off 

 into convenient segments and the vegetation mapped only in a 

 general way. Such general mapping takes into account (i) 

 the dominant and subdominant species, (2) all the species found 

 on the selected plot, (3) the density of the cover, and (4) the 

 grazing capacity of the plot expressed on an acreage or section- 

 tract basis of animal-unit capacity. The forage-acre equivalent 

 may be used to advantage if desired. The detailed mapping is 

 done, with variations, according to the quadrat method de- 

 veloped by Clements, the details of which are here summar- 

 ized under the various headings which follow.^ 



Sample plots are named according to the way the mapping 

 is done. In grazing work, the chart plot, the list plot, and 

 the denuded or depopulated plot are used most extensively. 



Chart Plot. — If the changes in the vegetation are to be 

 noted in detail, the chart plot is invaluable. Here ordinarily 

 all of the vegetation within the plot is charted in situ, but in less 

 intensive work the maps show only the species of primary in- 

 terest in the investigation pursued. If all the vegetation is to 

 be located in position on the map, as shown in Figure 123, the 

 standard size of quadrat, namely, the meter-square area, is 

 commonly used. 



A distinct disadvantage in the extensive use of chart plots is 

 the great amount of tedious work involved in the mapping and 

 in the subsequent crystallization of the data recorded. For 

 this reason the regular chart plot is less popular than formerly, 

 for certain other short-cut methods have been developed in 

 grazing studies which show well the changes in the vegetation. 



' Clements, Frederic E., "Plant Succession: An Analysis of the Development of 

 Vegetation." Carnegie Institution of Washington, Pub. No. 242, pp. 423-442, 1916. 



