cook: vegetation in southern peru 287 



are as low as 9000 feet, with the present glaciers ending from 

 2000 to 4000 feet above. Under the Peruvian conditions it does 

 not seem unreasonable to believe that the removal of a forest 

 covering might tend to bring about a recession of the glaciers. 

 Greater exposure of the rocky slopes would bring increased heat 

 and dryness of atmosphere. Less snow would fall and the ac- 

 cumulations on the high summits would be exposed to longer 

 periods of melting under direct sunlight. 



As trees are often found above the moraines, there is no reason 

 to doubt that the ancient forest covering extended up to the 

 glaciers, as forests are known to do in other glacial regions. 

 Several isolated tracts of forests have been found by Professor 

 Bingham at very high elevations, even up to 15,000 feet. These 

 high-altitude forests are of interest as affording the most definite 

 demonstration of the fact that tree growth is not limited by 

 elevation alone. 



ANDINE FOREST FLORA . 



The possibility of a forest covering for all of the inhabited 

 areas of this region is shown not only by the fact that trees 

 grow when planted, but also by the presence of an indigenous 

 forest flora whose different components are well adapted to the 

 various natural conditions afforded by different exposures and 

 elevations, up to the line of glaciers. 



Two of the high-altitude trees, quenuar (Polylepis) and quisuar 

 (Buddleia), have been noted frequently by travelers because 

 they are often planted in villages or allowed to grow among the 

 fields. (See fig. 1) Other members of the Andine forest flora 

 of southern Peru are lambran (Alnus), chachacoma (Escallonia), 

 unca (Eugenia), lengli (Hesperomeles), quisca (Berberis), mulli 

 (Schinus), chicjlluromay (Vallea), and numerous other trees, 

 including various arboreal Compositae. Several of the genera 

 are represented by two or more species. Some of these, such 

 as the species of Escallonia, are reported by botanical writers 

 only as shrubs, but under favorable conditions they attain true 

 arboreal proportions, especially at altitudes of 10,000 to 12,000 

 feet. 



