THINNING. 289 



develop in the most advantageous manner ; consequently such 

 trees are likely to assume a thin, lanky shape, so that they 

 are frequently unable to stand upright, if deprived of the 

 support of their immediate neighbours. They are liable to be 

 ])ent and broken by wind, snow, or rime. To obviate such a 

 state of affairs the forester interferes in good time by removing 

 a portion of the trees ; he tit ins the wood. Thinnings, then, 

 are cuttings, which have for their object to provide for each 

 tree left standing that growing space, which is best suited for 

 its further development according to the objects of manage- 

 ment. It is necessary to exj^lain this somewhat in detail. 



2. TJtc most suitable Groiiing Space. 

 As the objects of management differ, so must the most 

 suitable growing space. A})art from this the growing space 

 differs according to the age of the wood, the species, the soil, 

 elevation and aspect of the localit3\ 



a. Objects of Management. 



A tree growing in a free position, in complete enjoyment of 

 vertical and lateral light, will develop a full crown and root 

 system, and lay on a maximum of volume. This is no doubt 

 a great point, but it is counterbalanced by serious drawbacks : — 



In the first place a wood grown in this fashion does by no 

 means always produce the greatest volume per acre, as the 

 total production is represented by the average volume per 

 tree multiplied by the number of trees per acre. Although 

 each tree in a crowded wood has a smaller volume than one 

 grown isolated, yet, owing to the greater number of trees per 

 acre, a crowded wood may have, and generally has, a greater 

 total volume per acre than one in which the trees grow 

 isolated. Secondly, isolated trees are liable to suffer in height 

 growth and in straightness. In the third place, such trees are 

 frequently covered with branches low down, and in consequence 

 they produce less valuable timber. In the case of conifers the 

 timber is also liable to be of an inferior quality, owing to the 

 greater breadth of the concentric rings. Last, but not least, 



