430 THE INVESTIGATION OF SUCCESSION. 



striking results. The denuded quadrats permit the ready analysis of the 

 basic processes of migration, ecesis, competition and reaction, and the instru- 

 ments furnish the necessary data as to the controlhng physical factors. 



If the analysis of processes and habitat is to be as thoroughgoing as possible, 

 it is necessary to use a sequence of denuded quadrats. A time sequence is 

 established by denuding one quadrat each year, each new area being separated 

 by a space of a meter or so from the preceding one, so that invasion may occur 

 from all sides. In this way it is possible to reproduce a complete series of 

 stages, and to have them in close juxtaposition for comparative study. A 

 quadrat sequence in space may also be used for the analysis of reaction, by 

 denuding a series of areas in the same community in different ways or to 

 different depths. 



Various quadrats — ^With more or less modification, the quadrat method may 

 be applied to all plant communities, even in the most extreme areas. In 

 fact, some of its most striking results are obtained with the pioneer com- 

 munities in water and on rock. Chart quadrats of aquatic consocies are 

 readily made, though permanent and denuded ones present obvious difficulties. 

 Lichen and moss quadrats, on the other hand, are easily made permanent, or 

 are readily denuded. Those under observation in the Rocky Mountains 

 promise most interesting results, though the changes are necessarily slow. 

 Subquadrats of parasitic and saprophytic conununities on bark, fallen trunks, 

 and on the ground may likewise be made permanent, though the results are 

 of secondary importance. Moreover, it seems probable that the use of soil 

 quadrats will open a new field of study in enabling us to analyze the root 

 relations of communities with much greater accuracy. 



The transect— The transect (Clements, 1905 : 176; 1907 : 210) is essentially 

 an elongated quadrat. In its simplest form it is merely a line through a 

 community or series of communities, on which are indicated the individuals 

 of the species met with. The value of such a Une transect Ues chiefly in the 

 fact that it reveals the larger changes of popxdation, and hence serves as a 

 ready means of delimiting ecotones. The belt transect consists of a belt of 

 varying width, from a decimeter to several meters or more. It corresponds 

 to the chart quadrat, and likewise gives rise to permanent and denuded 

 transects. 



A line transect may be made by pacing an area and noting the species and 

 individuals encountered. The usual method is to nm a transect by means 

 of tapes. In the case of belt transects, two tapes are employed to mark out a 

 strip of the width desired. In grassland and undergrowth, a transect 2 deci- 

 meters wide is most convenient, while in forest 1 or 2 meters wide is most 

 satisfactory when reproduction is to be taken into accoimt. When the adult 

 trees alone are considered, the strip may be of any width. The transect is 

 located in the area to be studied by running the tapes from one landmark 

 to another, fastening them here and there by means of quadrat stakes. When 

 it runs through a diversified area, particularly in the case of transects 100 to 

 1,000 m. long, the topography is determined by means of a transit, and the 

 transect, when charted, is superimposed upon the topographic drawing. The 

 charting of transects is done in the manner already indicated for quadrats. 

 Because of their length, however, an assistant is almost indispensable in the 

 work. To save the handUng of many sheets, the practice is to record several 



