752 XLVI. VERBENACEAE 



invasion of grass, such as natural reproduction in groups. Leucaena glauca 

 is sown mth the view of keeping dowTi a heavy growth of grass. 



Mohnyin aTid Bilumyo forests. The Mohnyin and Bilumyo forests in the 

 Katha district of Upper Burma have already been described. They are 

 situated near each other, on fairly level ground, and have an aggregate area 

 of 27,489 acres. Teak occupies less than one-third of the area, but where it 

 occurs it constitutes a greater proportion of the stock than is usual in the 

 teak forests of Burma, becoming almost pure in places. The absence of bamboos 

 over most of the area further increases the dissimilarity between these forests 

 and the usual types of teak forest in Burma. The teak trees attain very large 

 dimensions, and large trees are much in excess. A feature of these forests, 

 which for some time caused uneasiness, is the almost entire absence of natural 

 reproduction of teak. With the view of devising means of inducing reproduc- 

 tion, experiments were commenced by the late Mr. J. Messer about 1898 and 

 continued for some years ; they were subsequently carried on in turn b} 

 Messrs. McHarg and Blanford. These experiments demonstrated the fact 

 that abundant natural reproduction, from teak seed lying dormant in the 

 ground, could be induced by opening the canopy and by compJeteiy clearing 

 and preferably burning the undergi'owth. They showed, however, that the 

 seedlings were rapidly kUled off during the rainy season by the di'ip from 

 overhead trees and by the weeds which sprang up. This indicated the pro- 

 cedure to adopt, namely, to remove all overhead cover possible, to cut and 

 burn the undergrowth, and to weed and clean the young teak crop for two or 

 three years. Figs. 287, 288, and 289 show the profusion with which natural 

 reproduction of teak is capable of establishing itself under this treatment in 

 areas in which it is entirely absent where these measures are not taken. 



A working plan based on the results of these experiments was prepared 

 by jMt. Blanford, and came into force in 1910-11, the fellings being prescribed 

 for 20 years. The rotation adopted is 180 years, corresponding to an average 

 girth of 8 ft., and is divided into nine regeneration periods of 20 years each, 

 the periodic blocks being so allotted as to contain as far as possible an equal 

 stock of teak. The working plan prescribed that periodic block I, to be 

 regenerated first, should be divided into four 5-year coupes or compartments, 

 corresponding to 5-year sub-periods, regeneration felHngs being carried out 

 by felling over the whole compartment in the first year of the sub-period, or 

 failing this by the second year, all teak except promising compact groups of 

 young trees. This prescription has subsequently been modified to allow for 

 annual instead of 5-yearly coupes, in order to ensure complete extraction in 

 one year over a definite area. The working plan prescribed the retention of 

 exceptionally well-shaped clean-boled teak below 6 ft. in girth, even if 

 isolated, but this has been found to be unsatisfactory, and is not acted on. 

 The aim is to effect as complete a clearing as possible in order to prevent 

 seedlings being killed by drip from overhead trees. All felled material which 

 can be disposed of is at once extracted, after which the whole area is thoroughly 

 burnt, all unburnt material being cut up, piled, and reburnt ; if complete 

 burning is not effected the first year, burning has to be repeated the second 

 year. The working plan prescribed burning for two years prior to girdling, 

 but this has proved to be a mistake, since it induces the germination of numerous 



