RELATIVE FORM AND SIZE OF MAIN THEE PARTe. 8 



Section I. — Relative foem and size of the main parts 



OF THE TEEE. 



The main causes of differences in these attributes are — 

 (i). Species. — In the firs and deodar the stem extends right up 

 to the highest point of the tree, and the branches have 

 a comparatively slight development, especially in the 

 case of firs, which possess branchlets rather than 

 branches. Pines and some broad-leaved species, such 

 as teak, simal, resemble firs and deodar up to a certain 

 age ; then a true crown, including little or no part of 

 the stem, is'formed. All other broad-leaved species (by 

 farthe largest majority of them) develop a distinct 

 crown in middle age, many even earlier, especially 

 when growing isolated. 

 (ii). Density and relative height of surrounding leaf-canopy. — 

 It is a universal rule that the denser and taller the 

 leaf-canopy is in which a tree has grown, the larger is 

 the proportion of stem in the tree ; and the smaller, in 

 the same measure, the proportion of branch wood, and 

 some times also the mass of wood in the roots. These 

 results are most marked in the case of broad-leaved 

 species. Some large broad-leaved species, such as the 

 mango, if grown isolated, branch only a few feet from 

 the ground, and the old trees thus consist of a thick 

 short stem dividing into massive, more or less horizon- 

 tal boughs. Such trees are often, if not generally, 

 shade-enduring. There are several shade-avoiding 

 species, which develop a conspicuously long stem even 

 in complete isolation, e.g., liardwickia hinata, teak, 

 Dalbergia Sissu, Adina cordifolia, ^c. 



(iii). Age. — In a canopied crop the toppings at first consider- 

 ably exceed the quantity of material in the timber 

 portion of the stem. In middle age the proportion 

 of this latter is already very large, and goes on increas- 

 ing, so that when the trees are large enough to be ex- 

 ploitable the branch wood may constitute only from 8 

 to 10 per cent, of the entire felled material. It is 

 obvious that the quantity of wood in the roots goes on 

 steadily increasing with age. 



(iv). Soil and locality. — It is a fact proved by universal expe- 

 rience that the proportion of wood in the stem increases 

 with the favoui-able character of the soil and locality, 



