176 THE FORMATION 



photographs often taken from a boat, but otherwise the usual methods apply, 

 at any rate for bogs and shallow bodies of water. In lakes or streams the 

 tapes might be attached to buoys or floats. The determination of factors is 

 made as usual. Permanent quadrats are feasible in many cases at least, and 

 denuded quadrats are not altogether impossible. 



TRANSECTS 



217. The transect is essentially a cross section through the vegetation of a 

 station, a formation, or a series of formations. It is designed primarily to 

 show the order of arrangement of species in zones and societies, but it also 

 serves as a record of the heterogeneity of any area. In the form of the layer 

 transect, it furnishes a graphic method of representing the spatial relations 

 of the species in layered formations, e. g., forests, ponds, and lakes. It is 

 merely a logical extension of the idea underlying the quadrat, and the tran- 

 sect is, indeed, little more than an elongated quadrat. An important differ- 

 ence, however, lies in the fact that the former normally traverses areas more 

 or less unlike, while the latter is always located in a homogeneous one. Fur- 

 thermore, the transect is plotted with especial reference to the topography. 

 With respect to dimension, transects are classified as line, layer, and belt 

 transects, and the latter may also be permanent or denuded. 



The Line Transect 



218. Description and mettiod. A simple transect is sometimes made by 

 establishing the points between which it is to be run, and then recording the 

 plants pace by pace along this line. This is satisfactory where the striking 

 changes in structure are desired. A more accurate method is ordinarily used, 

 since it gives detailed results, and at the same time brings out the more gen- 

 eral features. For this, use is made of a tape of proper length which is 

 divided into decimeters. Tapes of 10, 50, and 100 meters are used, and if 

 they are furnished with eyelets, transects of intermediate lengths may be run 

 with them. When longer transects are desired, as in the case of forest for- 

 mations, tapes of 5CX) or 1,000 meters should be used with eyelets a meter 

 apart. The transect is located in the area to be studied by running the tape 

 from one landmark to another, fastening it here and there by means of quad- 

 rat stakes. Previous to this, the shortest distance between landmarks is as- 

 certained when the transect runs through a depression or upon a level surface. 

 In the case of an elevation, the height is ascertained by a barometer, the 

 length and angle of the two slopes obtained, and the length of the base line 

 determined from these data. The field record of the arrangement of the 



