584 



ZONES OF ALPINE VEGETATION. 



plains, decreases with the elevation on dry mountain slopes, till at the 

 height of 8,526 feet, it is as 1 to 7. Moist mountain slopes favour 

 Monocotyledons, the proportion on them being as 1 to 3. 



1160. The following table shows the height at which corn and trees 

 grow in different quarters of the globe: 



Frigid 

 Zone. 



Torrid Zone. 



Temperate Zone. 



Andes, 



Lat. 



Inferior limit of per-) f 



petual snow, ) 



Upper limit of trees, 10,800 

 Distance between S . . _ _ 



trees and snow, ./ ' 

 Distance between \ 

 snow and corn,../ 



.3,78: 



4,200 2,700 



In the Himalaya, the upper limit of trees on the south side is marked 

 by Quercus semecarpifolia, at 11,500 feet, and on the north side by 

 Betula alba, at 14,000 feet. The Birch also forms the limit on the 

 Caucasian mountains. On the Pyrenees and Alps, the limit of trees 

 is marked by Coniferae; on the Pyrenees, by Pinus uncinata; on the 

 south side of the Alps, by Larix europsea, the Larch; and on the north 

 side, by Abies excelsa. In Lapland, the Birch forms the upper limit 

 of trees. The upper limit of shrubs is determined by the Rhododen- 

 drons in the Old World, on the Pyrenees at 8,312 feet, and on the 

 Alps, at 7,480; and by Bejarias on the Andes, at the height of 13,420 

 feet. On the south side of the Himalaya, Juniperus, Salix, and Ribes, 

 form the upper limit of shrubs, at 11,500 feet; on the north, Genista 

 versicolor ascends to 17,000 feet. 



1161. The following have been given by some authors as the zones 

 of Alpine vegetation: 



1. Region of Lowland cultivation. Its extent of elevation is at the spot where 



the prevailing cultivated plants of the latitude cease to be productive. In 

 Mount JEtna, it rises to 3,300 feet; on Teneriffe, to nearly 3,000 (zone of 

 vines). It embraces two zones of the Cactus and Euphorbia in the Can- 

 aries. In Madeira, it embraces two regions of Spix and Martius ; the region 

 of tropical plants reaching to 700 feet, and the region of the vine, fruit, and 

 corn, to 2,300. In Norway, Sweden, and Finmark, it is narrow. In the Car- 

 pathians, it rises to 1,500 feet. Within the tropics, it is a broad and im- 

 portant region. On the Andes, at Quito, it only ceases at 5,000 or 6,000 feet. 



2. Region of Woods. A magnificent region in all Alpine districts, and well 



characterized on the Andes and Himalaya. Humboldt notices it in Ten- 

 eriffe. In ^Etna, it extends to 6,200 feet. In the Canaries, to 4,080. In 

 Madeira (region of Chestnut), to 2,950. In Lapland, it extends to 800 

 feet. In Finmark, 70 north latitude, to 730. 



3. Region of Shrubs. Region of Retama (Spartium nubigenum) in Teneriffe. 



On the Pyrenees and Mont Blanc, it is extensively covered to about 9,000 

 feet with Rhododendrons. In the Andes, about Quito, it reaches 13,000, 



