and Magazine of the Ceylon Agricultural Society.— May, 1910. 



461 



I have always considered the herring-bone 

 system the most rational and theoretically the 

 most correct, because as long as a clear space is 

 left on either side of the tree (i.e., not allowing 

 the lateral arms to overlap) there is always room 

 for the sap to follow a natural and normal course. 

 The Question of Width. 



(2) The articles goes on : — 



One thins sure is that they must grow so widely apart 

 that neither under ground nor above ground may they 

 interfere with each other's development, and the study of 

 this point has led to the acknowledment of 15, ] 7 or even 

 •20 or more feet intervals as desirable, for in the struggle of 

 the trees for the mastery even the surviving fittest surfer 

 severely, and their development is delayed, to obviate 

 which thinning is resorted to. and must be started as soon 

 as the struggle begins, etc., etc. 



In spite of the above statement, we find under 

 the last heading of " initial close planting" the 

 words : ' "A maximum production is better assured 

 by initial close planting, for, if widely done at 

 first, we find awkward unequal gaps later on." 



Can anything be more contradictory ? And 

 why should the gaps occur if the operation 

 known as " supplying " is properly attended 

 to from the beginning ? I must confess that on 

 the numerous well-managed estates that I have 

 seen in Ceylon, South India, &c, the gaps have 

 been conspicuous by their absence, and the 

 trees extremely even when planted 20 ft. by 20 ft. 

 Effect of Close Planting. 

 In forestry, by close planting of timber species, 

 such distances as 3 ft. by 3 ft. and 4 ft. by 4 ft. 

 are implied, and I assume the article refers to 

 distances of this kind. Close planting intensi- 

 fies the struggle for existence, and generally 

 speaking, the closer the planting the keener the 

 struggle ; but 1 hardly think it is strictly correct 

 to say, " for in the struggle of the trees for the 

 mastery even the surviving fittest suffer severely. " 

 At any rate, this is an extremely far-fetched 

 way of looking at it, and tends to be misleading. 

 The struggle for existence commences as soon an 

 the young trees begin to interfere with, and 

 orowd, each other. In this struggle threo dis- 

 tinct types of trees are established, viz.:— 

 (a) Dominant trees, (b) Dominated trees. 



(c) Dead and dying trees. 

 Wherever possible trees of class (c) are left as 

 a covering to the soil, unless they are interfering 

 with the development of members of classes (a) 

 and (b), or where their usefulness as convertible 

 timber is greater than their utility as a soil cover- 

 ing. After a certain period, therefore, class (c) is 

 eliminated from the struggle, which goes on bet- 

 ween (a) and (b). It is now that the skill of the 

 "thinning operation" comes in. For example, if a 

 dominant tree is keeping back two dominated 

 trees, the crowns of which could quickly expand 

 and fill the gap caused by the removal of the 

 dominant tree, it would obviously be correct to 

 fell the latter. Again, if a dominated tree were 

 interfering with the proper development of a 

 dominant, or a more promising dominated tree, 

 it would be correct to remove it, and so on. 

 This process of elimination goes on until the 

 regeneration fellings are reached, when the 

 process changes to the leaving of those likely to 

 prove the best "parent" trees. Lastly, at the 

 period of the rotation, the final felling takes place. 

 Close Planting. 

 Now, with regard to the effect of closo plan*: 

 jng op individual trees, it stands to reason that 



the closer the planting, the greater is the 

 check on lateral growth, and, therefore, the 

 greater the development in the unly possible 

 direction, namely, upward. The result is a 

 plantation of long, whippy stems closely 

 crowded together with small conical-shaped 

 crowns, all jostling and crowding one another 

 to get up to the light. Now is the time 

 when, by judicious periodical thinnings, 

 the crowns of the better trees are given more 

 room, made to spread out umbrella-wise 

 and by having more leaf surface spread out to 

 receive the sun's rays, more CO^ is absorbed, 

 more plant food is formed, and consequently, 

 girth increment is quickly added, giving the tree 

 stability. I take it that the words "for, in the 

 struggle of the trees for the mastery, even the 

 surviving fittest suffer severely," refer to this 

 delaying of the ability of the trees to put on girth 

 increment. But surely there is no suffering 

 here, for though the surviving fittest are not 

 adding girth increment at first, they are reach- 

 ing the light, vanquishing their fellows and so 

 qualifying themselves for girth increment later 

 on, and that is why I think these words, and 

 also the subsequent words, "with close planting, 

 the improvement of the crown is stimulated," 

 are somewhat misleading and contradictory. In 

 this latter case, absolutely the reverse to stimu- 

 lation of the crown is the result until the sur- 

 viving trees have established their predominance. 

 Effect of Wide Planting. 



Conversely to the above, the effect of wide 

 planting is to lessen the struggle for existence 

 proportionally, and so increase lateral growth 

 by stimulating, through the medium of light 

 the activity of adventitious buds, and to dimin- 

 ish the intensity of upward growth. The result 

 is a bushy formation at first, developing into an 

 umbrella-shaped, short-stemmed tree. Fortu- 

 nately, in the case of Hevea, the strong, 

 warm, forcing soils and hot-house, tropical 

 atmospheres in which it thrives best have given 

 it the characteristic, under such conditions, of 

 a clean, whippy stem from the initial stage, as 

 onposed to the undesirable bushy formation. 



Now, in the case of timber production, the 

 object aimed at is the production of the greatest 

 possible amount of timber per unit of area, 

 whilst in the case of Hevea, and, in fact, all 

 rubber-producing species, the object is the pro- 

 duction of the greatest amount of bark surface 

 for tapping, for the greater the bark area the 

 greater the amount of laticiferous tissue. 



Given, therefore, the above favourable charac- 

 teristic of Hevea, wide planting enables it to 

 spread out its crown to the sun without inter- 

 ference from its neighbours, which it would 

 appear to begin to do from the age of about 

 three years onward. 



With a planting distance of 20 ft by 20 ft, 

 therefore, each tree would have a crown spread 

 of 20 ft at the widest part and an outside circum- 

 ference of something over 60 ft. In Brazil, 

 where the Hevea, in its indigenous forests, has 

 to participate in the struggle for existence, the 

 surviving trees often attain great height and 

 girth, but then the ago at which tapping is com- 

 mercially possible is probably much greater 

 than in artificial plantations, where it is given full 

 (Continued on page 464,) 



