532 



USEFUL PLANTS AND PLANT PRODUCTS 



is, by cutting away a ring of sapwood and allowing the trees 

 to die of starvation and lack of water. Cultivation was car- 

 ried on among them, until after some years the trees would 



FIG. 394. A corn field in a " deadening 1 ' or girdled forest of 

 deciduous trees 



Modified after Ay res 



fall and then were burned to rid the land entirely of their 

 presence. More than a century and a half of wholesale destruc- 

 tion of trees has finally resulted in stripping large areas of the 

 original forest and preventing the reforestation of the land, until 



