166 UTILIZATION OF LEAVES. 



leaf-canopy during the other halt is the only means of maintaining 

 the productiveness of the soil ; and (5) during the season of vege- 

 tation, when the soil must be in the most favourable condition 

 possible. 



In regulating the removal of dead leaves, two precautions must 

 never be omitted : (1) a rotation must be established, and (2) 

 measures must be taken to ensure a part of the annual fall being 

 left on the ground. The length of the rotation will depend, princi- 

 pally, upon the nature of the soil and locality and the largeness of 

 the demand, and, secondarily, upon the component species, the age 

 of the crop, and the method of treating the forest. The more un- 

 favourable the soil and locality and the heavier the demand, the 

 longer must be the rotation. So also a young or an old crop, an 

 exacting species, and a system of treatment which exposes the soil 

 for long intervals, will require a long rotation. The saving of some 

 portion of the annual leaf-fall is ensured by allowing the dead 

 leaves to be collected only wliile they are falling and only during 

 the first half of this period. A combination of the two precautions 

 in question will never fail to result in a considerable quantity of 

 leaves being left on the ground to decompose and form humus and 

 enrich and improve the mineral soil below. 



Section IV. — Leaves foe thatching. 



Where palms grow in abundance, the leaves often form the en- 

 tire thatching put into a roof. Before using the leaves, they .should 

 be placed over one another, on a dry floor, with the leaflets proper- 

 ly spread out, so that they may dry quickly and well flattened out. 

 When dried thus, they are easily arranged over one another in the 

 roof. If the leaflets are long and narrow, like those of the cocoa- 

 nut palm, they may be plaited together into a sort of matting. 

 Palm thatching seldom requires renewal oftener than once in three 

 or four years, and then too it is only the upper layers that need 

 replacement. Thatching composed of leaves of the Wallichia den- 

 siflora is extremely durable. 



The leaves of other species, and also often of palms, are laid 

 under or between grass thatch. By increasing the tightness of the 

 roof, they enable it to be made extremely thin and light. Before 

 the leaves can be used, they must be dried, after being pressed to- 

 gether and tied up in bundles. The leaves of teak and of Bauhinia 

 Vahlii, especially the former, are extensively so used and constitute 

 an article of considerable export. Any broad fibrous leaf serves for 

 thatching, and accordingly the loaves of miuiy other si)ocics, such 



