MIXED CEOP OF UNIFORM AGE. 37 



proportion to the persistence of the leaves of any of the component 

 species will be the lightness of a conflagration under individuals, 

 and especially groups of individuals, of that species. Thus, other 

 circumstances being the same, the more nearly evergreen a species 

 is, the less will it be injured by forest fires. Moreover, if the trees 

 are completely evergreen, the quantity of dead inflammable matter 

 under them at any time will always be less than under decidous 

 trees. All the preceding remarks apply in their fullest force when 

 the trees in question form groups ; but even isolated individuals, by 

 the advantage they enjoy over their neighbours belonging to less 

 favoured species, will, soon after they become fertile, surround them- 

 selves with their own progeny, which will act as a further check to 

 the violence of conflagrations ; and in this way groups must form 

 and go on extending themselves. The facts recounted above are 

 forcibly illustrated by the numerous natural belts of the Bauhinia 

 climber found in so many of our forests which oppose an almost in- 

 surmountable barrier to the progress of a conflagration. Foresters 

 in Central India, in fire-tracing operations, know how to turn to 

 account masses of Ougeinia dalhergioides flanking their fire-Hnes, for 

 that species is in full leaf at the time of those operations and no 

 guide or check Hne need be cleared along their edge, as the fire 

 from the trace cannot spread into them. Many sal forests are also 

 io a great extent thus self-protected, the sal being very nearly an 

 evergreen. 



(ii) The season of leaf-fall. — Some trees shed their leaves in the 

 cold weather, so that by the time the season of forest fires arrives, 

 the dead leaves have scattered and, owing to the winter rains, have 

 settled into a close mass, which naturally cannot flare up as high as 

 loosely packed leaves that have just fallen. On the other hand, if 

 fire sweeps through a crop before all the trees have shed their leaves 

 for the year, those still retaining them will generally have less com- 

 bustible matter under themselves than all the rest, the diflference be- 

 ing most marked if those are evergreen and these deciduous. Fires 

 are generally least harmful before a tree has begun to lose its old 

 foliage. 



(iii) The season of appearance of a new flush of leaves. — It is 

 obvious that if a fire occurs when a new flush is in process of 

 coming out, the tender succulent leaves must, as a rule, be entirely 

 destroyed, unless the quantity or nature of the fallen leaves does 

 not allow the flames to rise up into the crowns. The trees that thus 

 lose their first flush of leaves, can evidently put forth only a com- 

 paratively poor second .flush, and, if this destruction of the first flush 



