METHODS OF STUDYING VEGETATION 209 



by another, i.e., in the process called succession, in which the use 

 of the permanent quadrat is imperative. 



The permanent quadrat is a meter square. It should be located 

 in a station where readings of physical factors are taken. If suck 

 quadrats are established elsewhere, readings should be made in 

 them in so far as possible. Permanent quadrats are staked and 

 mapped in exactly the same way as chart quadrats. The quadrat 

 is fixed by driving a labeled stake at the upper left-hand corner,, 

 so that its edge indicates the exact position of the quadrat stake. 

 A smaller one is placed at the opposite corner to facilitate the 

 task of setting the tapes accurately in later readings. The label 

 stake bears merely the number of the quadrat and the date when 

 it was first established. It is driven in firmly and is allowed to 

 project just enough to enable it to be re-located with readiness. 

 The use of natural or artificial landmarks is necessary in order 

 that the stake may be found easily upon successive visits. At 

 each subsequent visit the tapes are placed with reference to the 

 stakes, and a chart is mapped in the usual manner. These are 

 labeled and dated like the original ones, but they are numbered 

 to indicate both the quadrat and the visit, e.g., 15^ is the second 

 chart made of quadrat 15. 



224. The denuded quadrat. This is ordinarily a permanent 

 quadrat, from which the plant covering has been removed after 

 a chart and photograph have been made. Practically the same 

 thing is obtained by staking a permanent quadrat in a new soil 

 or in one recently laid bare. The denuded quadrat is of the usual 

 size, 1 meter. It is especially adapted to the study of invasion 

 and the resulting competition, and throws a flood of light upon 

 the development of formations in the course of succession. 



Permanent quadrats may be denuded at any time that seems 

 desirable. The best practice is to establish two side by side, 

 and then denude one of them, the other serving as a control. A 

 quadrat which is to be denuded is first mapped, photographed, 

 and labeled exactly like a permanent one. The vegetation is then 

 destroyed, usually by removing it with a spade. Ordinarily the 

 aerial parts alone are removed by paring the surface of the ground. 

 When it is wished to trace the consequences of a greater disturbance, 

 the upper seed-bearing layer of soil is removed and the underground 

 parts dug up. Quadrats are usually denuded in the fall, at or 

 near the close of the growing ]xriod, though it may also be done 



