18 VEGETATION OF THE PEAK DISTRICT [CH. 



regards their floristic composition and their general life con- 

 ditions. Similarly, he may easily recognize other plant 

 associations on the hill slopes of the district. 



Vegetation Maps 



In this way the observer determines that certain plant 

 associations are typical of certain limited areas ; and it becomes 

 possible to construct vegetation maps on which the distribution 

 of these associations may be shown. The number of the plant 

 associations which may be indicated on a map depends very 

 largely upon its scale. The bigger the scale of the map the 

 more the plant associations which may be shown upon it ; and 

 considerable judgment is required in deciding which associa- 

 tions shall be shown on a map of any given scale. In deciding 

 this difficult but very important question, several general con- 

 siderations must be borne in mind. 



The object of a vegetation map of a district under investiga- 

 tion is to give the best possible cartographical representation 

 of the plant communities which the scale of the map will allow. 

 On the one hand, the fullest advantage must be taken of the 

 size of the scale employed ; and, on the other hand, the map 

 must not be so crowded with details that it loses in definiteness 

 and clearness (cf. Flahault and Schroter, 1910: 11). The 

 experience of phytogeographers in this country is that the 

 scale of one inch to the mile (1 : 63,360) is a suitable one for 

 maps intended to show the distribution of the more important 

 plant associations of the British Isles, and that maps of a 

 smaller scale are not desirable except for special purposes. 



It is obvious that every plant community cannot be indicated 

 on a map of this scale (1 : 63,360); and hence the plant 

 geographer has frequently to subordinate minor units of 

 vegetation to units of wider significance; and, in such cases, 

 the plant geographer has to determine the larger vegetation 

 units to which the minor units must be subordinated : other- 

 wise, the colours on a vegetation map will be mere empiricisms 

 and without any philosophical basis. It is obvious, therefore, 

 that no one can successfully construct a really scientific 

 vegetation map unless he has specially considered the inter- 

 relationships of the fundamental units of vegetation. 



