I 68 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



The growth made during the summer months has proved 



variable in different seasons. To analyse the figures in detail 



for each year would occupy too much space. The following 

 are the average results — 



The general conclusions which may be drawn from these 

 figures appear to be that in the average season timber increment 

 commences about the middle of May, and attains its maximum 

 in June, during which month one-third of the whole increment is 

 laid on. There is a gradual falling off in growth during July 

 and August, when in many cases increase in girth ceases. In 

 certain trees, especially on better soils, a small growth is made 

 in September. It has been observed that a cold backward 

 season with an absence of sun may postpone any timber 

 increment until June, but rainfall in the early part of the season 

 is not so important, no doubt because there is rarely any lack of 

 soil moisture at that period. Prolonged dry weather in the latter 

 half of June or in July has, however, a very marked effect on both 

 spruce and Japanese larch, although when sufficient rain does 

 fall the loss of growth is usually made up. It is clear, however, 

 that for Japanese larch the summer rainfall can hardly be 

 excessive, provided there is a reasonable amount of warmth. 

 In one or two seasons a slight growth has been noticeable in 

 the Japanese larch in April, but it has not been thought worth 

 while recording this separately, and it is consequently included 

 in May. 



