XYLIA 403 



mrface ; it avoids low-lying flat ground subject to inundation. The tree is 

 'ound on a variety of geological formations. On the sandstones and shales 

 )f the Pegu Yoma, producing a deep sometimes sandy loam, it thrives extremely 

 ^ell. In the Chindwin valley it is found, often of large size, on sandstone 

 md conglomerate with occasional shale, clay, or limestone. In the Ruby 

 ilines district it occurs to some extent on limestone, sandstone, slate, and 

 ihale. Mr. G. R. Jeffery ^ attributes its local occurrence in this district to 

 he fact that it avoids saline and ferruginous soils : thus, although it is present 

 i,nd abundant in the Hintha and Ondok blocks, it is wholly absent from the 

 leighbouring Kyauktaung block, where the soil is largely saline and ferru- 

 jinous. In the Madaya drainage of the Mandalay district it occurs on gneiss 

 .nd occasional limestone, while east of the Sittang river it is found on gneiss 

 bUd granitic schist. In the Thaungyin valley of Tenasserim it occurs on argil- 

 aceous sandstones and shales, on igneous or metamorphic rocks and on 

 Lmestone. In various localities it grows on recent alluvium, provided the 

 Irainage is good. In the dry zone of Upper Burma it is found to a very 

 imited extent and of small size on sandstone with alternating thin bands of 

 hale. Throughout its distribution it occurs locally and in stunted form on 

 j/terite in the dry dipterocarp forest known as ifidaing. 



In the natural habitat of the tree the absolute maximum shade temperature 

 aries from 100 to 113 F., and the absolute minimum from 40 to 55 F. 

 ^s regards rainfall requirements, it is actually found in limited quantity in 

 he dry zone of Upper Burma in places where the normal rainfall is as low as 

 in., though here it reaches only a small size. It may be said in general 

 hat where the rainfall is less than 45 in. it does not attain large dimensions, 

 r'hile it grows best with a rainfall of 60 in. and over ; actually it is known 

 grow extremely well with a rainfall of 120 in., and no doubt it thrives in 

 ven wetter localities. 



The tree occurs in five broad types of forest : (1) upper mixed deciduous 

 Drest; (2) lower mixed deciduous forest; (3) evergreen forest; (4) indaing 

 Drest ; and (5) scrub forest of the dry zone. 



1. Upper mixed deciduous forest. This is by far the most important 

 ype, and the one in which the trees are found in the greatest abmidance 

 nd attain the largest dimensions. This type is characteristic of hilly country, 

 lie hills being often little more than comparatively low spurs, as on the outer 

 :inges of the Pegu Yoma (see Fig. 155) : it is the type which comprises the 

 reat bulk of the more important teak forests of Burma, and is in the great 

 lajority of cases characterized by the presence of bamboos. There are many 

 ab-types of this type ; these can be classified to a large extent according 

 the moistness or dryness of the forest, the bamboos being the best indicators, 

 'he moistest sub-type is that which verges on evergreen, and often contains 

 ttle or no teak ; in this sub-type, which is well developed in the moister 

 3gions of the Pegu Yoma, pyinkado is sometimes so abundant as to become 

 ractically gregarious. This sub-type merges into the typical moist mixed 

 eciduous sub-type and thence through various stages into the driest sub-type 

 f mixed deciduous forest. The typical bamboo of the driest sub-type is 



^ Working Plan for the Hintha, Ondok, and Kyauktaung Reserves, Ruby Mines Division, 



308. 



F 2 



