3t 



PLANT snrioLOGY 



roots 1,515.3 g.). The principal part of the root mass is supplied by 

 Carex hosiii. 



Total Estimate. — For the minute monographic study of a definite 

 community, for studies of succession, or for the solution of a variety 

 of questions of more practical nature good results are obtained by 

 considering cover and density together. The question of whether the 

 results are likely to be commensurate with the labor involved must 

 always be considered, for the determination of density is usually very 

 troublesome and not alwavs feasible. 



Fig. 13.- 



Gtntiana costci (Soc. 1) and lin/jln,- ciicorum (>Sor. 3). 

 {Photo by Killer.) 



Causse Noir 950 m. 



A material reduction of the field work is attained by combining 

 the estimate of abundance and cover, ignoring density. For this a 

 conventional six-part scale is used. The meaning of the signs and 

 figures is as follows: 



+ = sparsely or very sparsely present; cover very small. 



1 = plentiful but of small cover value. 



2 = very numerous, or covering at least J-^o oi the area. 



3 = any number of individuals covering 3<4 to K of the area. 



4 = any number of individuals covering }-^ to % of the area. 



5 = covering more than % of the area. 



It is plain that the smaller numbers have more to do with abundance, 

 the larger with the cover. 



Each well-defined layer of vegetation must be estimated separately. 

 In the closed beech woods the beeches in the tree layer and Asperula 



