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. 
