60 SYLVICULTURE IN THE TROPICS ft. i 



covering extensive areas of country. But where they 

 are most abundant is where indiscriminate fellings 

 have been made, such as those preceding temporary or 

 shifting cultivation, i.e. a method of cultivation very 

 prevalent in the Tropics and consisting in raising crops 

 on forest land manured by the ashes of the trees that 

 stood on them. As this cultivation is carried on only 

 for a few years until large yields are no longer obtainable, 

 the blank spaces are abandoned and fresh clearings 

 made. Nature then uses the most ready means for 

 covering up the soil, and Lantana, whose edible seeds 

 are largely dispersed by birds and other animals, 

 has stepped in and covered the soil until shade-enduring 

 plants, springing up under its cover, push their heads 

 through and proceed to form tree cover. Another plant 

 following a similar role is the Mexican sunflower 

 (Tithonia diver sifolia), and in other places where the 

 Lantana has not arrived in time and which are no longer 

 suitable for its reception, the sun-loving fern, Gleichenia 

 linearis, and bamboo such as Ochlandra stridida, or, 

 on very exposed faces, the surface of which has been 

 washed off by tropical downpours, scanty shrubs and 

 undershrubs such as Hedyotis and various Composites. 

 In the montane zones the Arundinaria bamboo also 

 often covers large tracts and renders regeneration of 

 trees difficult ; and in Asia a widely represented genus, 

 that of Strobilanthes, forms dense thickets, which keep 

 all the light from the ground and thus retard natural 

 regeneration, especially in places where the seed being 

 light it cannot always reach the soil. In Ceylon, where 

 there is an extraordinary abundance of these plants, the 

 fruits or seeds of forest trees are mostly spherical and 

 heavy and belong to shade-enduring species which are 

 thus able to germinate and to maintain themselves 

 under cover until the periodic flowering and seeding of 

 the Strobilanthes, an event which occurs every 4-12 

 years, when the latter dies down and tree seedlings can 

 shoot up until they are again caught up and have to 

 wait another period under cover. This, of course, means 



