432 THE INVESTIGATION OF SUCCESSION. 



land and grassland areas the use of a transit or at least of a compass is neces- 

 sary. A label stake is driven at each end, on which is painted the number and 

 date of the transect, as well as its direction and length. The position of the 

 ecotones is indicated by smaller stakes bearing the transect number and the 

 date when the ecotone was found at that point. These are left in place as they 

 are added from year to year in order to indicate the shifting of the ecotone. 

 This is the chief use of the transect, and serves well to illustrate the difference 

 between the quadrat and transect. The permanent quadrat is intended to 

 give the composition and structure of a typical or representative portion of a 

 single community, and to enable one to follow its changes from year to year. 

 A series of quadrats makes it possible to establish spatial comparisons between 

 communities for any particular year, and has the incidental advantage of 

 making it imnecessary to chart the interveniag vegetation. This disad- 

 vantage of the transect, however, is more than offset by the unique values 

 obtained by being able to trace the change in the typical structiure and com- 

 position of a community or zone through the transition features of each 

 ecotone into the adjacent zones. It has already been emphasized that zones 

 are serai stages, and that ecotones make it possible to discover how one stage 

 passes into another, i. e., they are substages in essence. The transect alone 

 makes it possible to follow in detail the change from one zone or associes to 

 another through the ecotone, and hence is of the first importance in the inves- 

 tigation of succession, especially by the method of inference. In the case 

 of grassland and forest undergrowth, a combination of quadrat and transect 

 would seem to constitute the best method, but this has not yet been tried. 

 If the quadrats of a series through several zones were connected by narrower 

 transects, the masdmmn information would be obtained with the minimum 

 expenditure of time and labor. 



The denuded transect adds to the value of a permanent one by furnishing 

 new stages for the analysis of each zone and ecotone; hence the two should be 

 employed together wherever time and opportunity permit the most intensive 

 study. The simplest method is to chart a permanent transect of twice the 

 width, and then to denude one-half the width throughout. Since it is the 

 colonization on the bare strip that is of importance, a permanent transect may 

 be made in the usual way, and then a strip of equal width alongside of it 

 denuded without being charted. 



The bisect.— The layer transect (Clements, 1905:180) is used to show the 

 vertical relations of species in a layered community. Its value in succession 

 lies chiefly in recording the successive disappearance of layers as the climax is 

 reached. It has further value in tracing the beginnings of layering as competi- 

 tion passes into the dominance of medial stages. In all of these cases, root 

 relations play an important and often a controlling part. Hence they consti- 

 tute an essential portion of the record, and it is proposed to indicate the 

 vertical and lateral relations of individuals by means of a cross-section showing 

 both shoots and roots in their normal position. Such a cross-section may be 

 termed a Used (figs. 49, 50). In a purely diagrammatic form it has fre- 

 quently been used to show the relations of aquatic and swamp plants, but as a 

 means of showing the exact relations of layers, especially in the soil, it was 

 first employed by Yapp (1909 : 288) and Shantz (1911 : 51). The latter iised 

 it primarily to illustrate the reaction of root-layers upon water penetration, 



