cook: vegetation in southern peru 289 



wise complete clearing of the land for agricultural purposes. 

 Hardy types of woody vegetation, growing in the ravines and 

 on the rocky slopes above, might survive even long perods of 

 agricultural occupation of the terraced lands below. The neigh- 

 boring areas might be seeded easily from the old trees. Such a 

 ravine, leading up from the other side of the spur shown in the 

 figure, is now heavily wooded and contains many well matured 

 trees of the same species that now cover the terraces, although 

 very few of the trees appear to be very old or to have reached 

 the stage of natural decay. Some of the terraces in the Panti- 

 calla Valley are covered with much older trees than any found 

 in the valley above Ollantaytambo. 



HABITS OF SURVIVING NATIVE TREES 



Although the genera of native trees, as mentioned above, 

 belong to as many different families, there is a general similarity 

 in habits of growth, in that all of them sprout readily from the 

 stumps and endure repeated cutting. Seed is produced in a 

 few years, if the sprouts are allowed to grow. The limitation 

 of the present forests to such trees may be taken to indicate that 

 persistent vitality was necessary to pass through the periods 

 when these valleys were occupied by large agricultural popu- 

 lations, as shown by the extensive terracing of the slopes. A 

 period of complete denudation of a valley would mean the 

 extermination of all kinds of trees that were unable to sprout 

 from the stumps, but trees like Escallonia, Eugenia, and Schinus 

 might survive centuries of pollarding. The last is familiar as 

 the "pepper-tree," now grown by thousands in southern Cali- 

 fornia for shade and ornamental purposes. Other members of 

 the Andine tree flora are even more attractive in appearance 

 and promising for introduction into the United States. 



DENUDATION OF UNCULTIVATED LANDS 



The former presence of large agricultural populations accounts 

 not only for the clearing of all the lands that could be cultivated, 

 but also for the denudation of lands that were not capable of 







