TECTONA 729 



which is unusual in plantations, are probably a soil consisting of well-aerated 

 and well-di-ained sandy loam, comparative absence of heavj^ weed-growth, 

 and the open nature of the plantation, which contains fairly large gaps. 



Bamboos play an important part in connexion with teak reproduction, 

 particularly in Burma, where the nature of the bamboo growth exercises 

 a marked effect. Thus under the heavy shade of a dense growth of Bambusa 

 polymorjjJia or Oxytenanthera albociliata natural reproduction is rendered 

 impossible owing to the heavy shade, while under the lighter shade of Dendro- 

 calamus strictvs or Cephalostachyum pergracile, or where bamboo extraction 

 or elephant grazing has reduced the canopy of the bamboos, reproduction is 

 sometimes plentiful. The periodical flowering and dying of the bamboo, 

 provided the forests are not fire-protected, is known from actual observations 

 in Burma to exercise a marked stimulus on the establishment of teak repro- 

 duction. Measures for aiding the reproduction of teak in bamboo tracts are 

 described on pp. 756 to 761. 



Artificial reproduction. The question whether or not the formation r^ ^ 

 of teak plantations is justifiable on silvicultural or financial grounds has on \^\ 

 occasion been the subject of discussion. Opponents of the policy declare 

 that ^plantations are silviculturally unsound, since teak is not naturalty a 

 gregarious tree, and that plantations are more exposed to insect attacks than 

 teak in natural forest ; again, plantations were curtailed in Burma some years 

 ago on the ground that the staff and labour available were insufficient to cope 

 with the work of thinning extensive areas of plantation. It is true that teak 

 is not usually gregarious, though pure crops sometimes spring up on alluvial 

 flats and on abandoned cultivation, bu if pure plantations are objected to, 

 mixtures are always possible. Plantations are no doubt more liable to insect 

 attacks than isolated trees ; yet although the Nilambur plantations are 

 regularly defoliated, they have nevertheless proved a great financial and 

 silvicultural success. On the other hand, it is by no means certain that the 

 mixing of teak with other species can always be relied on to prevent insect 

 damage ; it is certainly disproved by a case recorded from North Yellore in 

 1917,^ in which a group of 15 teak trees planted in the midst of mixed forest 

 were attacked by Pyrausta, every leaf being skeletonized and the caterpillars 

 being found everywhere ; there were no other teak trees within miles. In 

 Burma the so-called bee-hole borer is a more serious menace than these defolia- 

 tors, and if some effective means of dealing with the pest cannot be devised 

 it may be advisable to mix the teak with other species or to limit the size of 

 the blocks to be planted with teak, separating them by fairly wide belts of 

 natural forest or by plantations of other species. 



Mr. C. F. C. Beeson has found that attacks of bee-hole borers are worse 

 in pure plantations than in mixed forests rich in teak ; he has also found 

 that a dense undergrowth of bamboos, and particularly of Bambusa poly- 

 morpha, acts protectively, lessening the severity of the bee-hole attack. The 

 borer can, according to Mr. Beeson, be dealt with to some extent in the conduct 

 of thinnings. Thus (1) if trees marked in thinnings are felled before the end 

 of the year, the borers in those trees will die ; (2) the removal of dominated and 

 suppressed trees not required in the crop removes a considerable proportion 



^ Conservator of Forests' Inspection Note, 1 91 7. 



