656 Ecology 



The main stress in these kixuriant forests is competition. For 

 plants it is an unending struggle for light, and for animals it is the prob- 

 lem of escaping predation. 



Biomes of a Smaller Extent. — In mountainous regions, it is pos- 

 sible to see biomes characteristic of more northern areas. Here the pres- 

 ence of these is due to the altitude rather than the latitude. Among these 

 are the montane tundra and the montane coniferous forest. These closely 

 resemble their northern counterparts except that they present the addi- 

 tional stress of low oxygen tension and greater wind velocities. While 

 their flora and fauna are very similar to that of northern areas, the larger 

 mammals are absent. 



\SNOW AND ICE 

 -SNOW LINE 



AND LICHENS 

 LOW HERBACEOUS VEGETATION 



Fig. 212. — Diagram to show correspondence of biomes met in ascending a 

 tropical mountain with tliose encountered from tlie base of the mountain to the pole. 

 (Modified with permission from Animal Biology, by Wolcott, copyright, 1946, by 

 McGraw-Hill Book Company, Inc.) 



The tropical deciduous forest is found in those areas of the tropics 

 where there is a marked alternation of wet and dry seasons. The trees 

 lose their leaves during the dry season, hence the name tropical decidu- 

 ous. The most extensive of these are the great monsoon forests of In- 

 dia. In Mexico, some examples are found along the west coast and on 

 the Yucatan Peninsula. 



The winter rain forests are found along the shores of the Mediter- 

 ranean and in parts of California. These small regions are at present 

 badly disturbed by man, but have become of great importance as citrus- 

 raising areas. They are characterized by a heavy winter rainfall. 



