92 THE DEVELOPMENT OF BRITISH FORESTRY 



July and January Means for various Stations in North- 

 Western Europe from Hann's Handhuch der Klimatologie, 

 and Meteorological Office records. 



Low-Level Stations 



The question then arises as to the climate most nearly- 

 approaching perfection for those species which are of 

 greatest importance in British forestry. The range of 

 amplitude in July mean temperatures varies generally from 

 54° F. in the north of Scotland to 62° F. in various districts 

 in the south, east, and midlands of England, or, roughly 

 stated, a difference of about 9". The British Isles, there- 

 fore, may be divided into three climatic groups, in each 

 of which certain species are found to succeed better than 

 others, as shown in the following table : — 



Climatic Grouts in British Isles as indicated by July 

 Means and the development of certain species of trees. 



I 



Jtdy Means of 54° to 56° F. 

 Species thriving best in these are spruce, Sitka spruce, 

 larch, birch, etc. Spruce and larch seldom attain large 

 dimensions on exposed sites with these temperatures. 



II 



Jidy Means of 57° to 5d° F. 

 Most suitable species are the majority of conifers, ash, beech, 



