24 FIRST BOOK OF FORESTRY 



Thus, we see that the soil determines the character of the 

 forest, but that the forest also has the power to modify 

 and improve the soil, and so enables the soil to grow 

 more trees and better trees. 



But this also teaches us that in all poor, sandy soils 

 the permanent removal of the forest and, especially, the 

 burning over of the sandy lands must needs injure the 

 land hy diminishing its fertility ; and that, therefore, it 

 is harder to start a forest, and the forest will grow much 

 less vig;orouslv on such maltreated lands. 



What Moisture does for the Woods 



On a trip along the Texas Pacific Railway from the 

 eastern boundary of Texas westward we first pass through 

 long stretches of pinery, then many miles of mixed for- 

 ests, which, on nearing the Trinity River, change into 

 more and more open woods composed almost entirely of 

 oak. From the Trinity westward these oak woods grow 

 more and more scrubby; the finest lands are prairies, 

 and the forest is restricted to the stretches of sandy lands 

 known as the Cross Timbers. 



After crossing the Brazos River, west of Graham, the 

 forests are reduced to patches in the river bottoms, and 

 the broad fertile lands are either treeless prairie or mes- 

 quite openings, where scattering bushes of the thorny 

 mesquite heli3 to relieve the monotony. 



