238 Studies in Forestry [CHAP. xi. 



time of underplanting a heavy thinning or partial clearance had 

 taken place. This was of itself at first sufficient to stimulate 

 the trees to the production of broader annual rings, but only 

 in such a manner as to induce a tapering form of bole owing to 

 broader zones being formed near the base than higher up the 

 stem. But ten years later, when the underwood began to form 

 canopy, the breadth of the annual rings diminished consider- 

 ably ; and, in the case of four out of six sample stems, this was 

 succeeded by a slight increase again during the third decade. 

 During the second decade, whilst the increment was slightly 

 diminished, there was a distinct tendency to approximate in 

 mode of increment towards what obtains in close-canopied 

 forest. That is to say, in consequence of the underwood form- 

 ing canopy, the annual rings near the base of the stem 

 became relatively narrower whilst those near the top of the bole 

 became relatively broader, with the result that the bole became 

 less tapering and consequently better-shaped, technically more 

 useful, and financially more valuable. This improvement, often 

 a very slight one only, is due to the fact that, owing to the 

 soil, and consequently the root-system, being kept cool, the 

 latter is not stimulated to the extraction and absorption of such 

 large quantities of nutrients as if warmed by free insolation. 

 Hence the quantity of assimilated nourishment and construc- 

 tive matter which is conducted downwards to the base of the 

 stem and to the root-system is less in amount than under these 

 other circumstances ; and as the total amount of food-supplies 

 is diminished, whilst the demands of the top part of the bole 

 for nourishment practically remain constant, less remains to 

 be utilized for constructive purposes towards the base and 

 throughout the root-systems of the trees. 



The second series of investigations was made on two Oak 

 standards of 105 years of age, which, after having stood for 

 about twenty to thirty years with their crowns freely exposed 

 to light and air, were underplanted at sixty-five years of age 

 with Beech. The latter is now about forty years old, forms 



