CLIMATE AND TREE GROWTH 97 



abundance of moisture, but it must be accompanied by a 

 certain temperature, shelter from strong winds, and a 

 porous soil, which may or may not be forthcoming on 

 a given area. The greatest amount of rain falls at high 

 elevations, and as is well known, tree growth at the 

 the latter is slower than at low levels, or ceases altogether 

 at elevations of 2000 feet or so. In sheltered positions 

 within 500 feet of the sea-level, many conifers grow better 

 with the heavy rainfall of the west coast than elsewhere, 

 but a porous soil is absolutely necessary for the success 

 of most. Many broad-leaved trees, on the other hand, 

 attain a poor development, or fail altogether in similar 

 situations. 



As regards the height growth of trees, the most 

 favourable index of climatic influence, data are more 

 difficult to obtain which are free from differences of soil 

 and situation. The yield tables of continental forest 

 statistics give us the height growth of thickly grown crops 

 at various ages, and from these Ave can form some idea 

 of the ultimate height growth attained by mature crops 

 in average localities in North- Western Europe. Data for 

 Scots pine, spruce, and beech are found in the table on 

 page 232. 



Statistics of British tree growth are more difficult to 

 obtain, except those relating to individual trees, and these 

 refer in many cases to those either remarkable for their 

 large girth or rarity, or trees which have been grown 

 under exceptionally favourable conditions. In any case, 

 they are seldom strictly comparable to the average 

 continental yield tables. Such, for instance, as have been 

 collected from various sources furnish the data shown in 

 the following table as regards height growth alone : — 



