ii8 Forestry Quarterly 



the Prairie, the Pacific, and the north Mexican. Under the 

 prairie region are not only inchided the forests of the Dakotas 

 and the other prairie States east of the Rocky Mountains, but also 

 the widely different Forests of southern Arizona and New Mexico ; 

 the latter, however, really belong to the North Mexican region. 

 The description of North American forests is necessarily brief, 

 and American foresters will find but little new and considerable 

 to criticise in its presentation. 



The forests of the old world are de.scribed under the Atlantic 

 or European forests and the Pacific or Asiatic forests. The 

 Atlantic forests are but briefly noted, but the Pacific forests from 

 which Europe draws a large number of exotic species are de- 

 scribed at some length, particular attention being given to the 

 forests of Japan, China, Korea, Siberia, Asia Minor, and the 

 Himalayas. This account of the Asiatic forests will be of par- 

 ticular interest to American foresters because a large number of 

 the exotic species grown for forest and park purposes in the 

 United States are from these forests. 



Following the descriptions of the forest regions Dr. Mayr pre- 

 sents an extremely useful and interesting discussion of the 

 climatic and species parallels of the forests of North America, 

 Europe, and Asia. The important factors taken into considera- 

 tion in the determination of forest zones are the relative humidity 

 of the atmosphere, the precipitation and the temperature, par- 

 ticularly of the season of principal growth, viz., from May 

 to August inclusive. The elevation above the sea is also con- 

 sidered and the lowest temperature of winter. The classification 

 of forest zones is as follows : 



A. Tropical forest zone, the Palmetum. 



B. Subtropical forest zone of evergreen oaks and laurels, 



the Lauretum. 



C. Warmer half of the warm temperate zone of broadleaved 



species, the Castaneum. 



D. Colder half of the warm temperate zone of broadleaved 



species, the Fagetum. 



E. Cold temperate zone of pine, fir, and larch, the Pinetum, 



Abietum, or Laricetum. 



F. Cold zone of crooked and stunted trees at tree limit, the 



Alpinetum or Polaretum. 

 The tropical forest zone is not described, as this zone does not 

 reach as far north as Europe. The other five, however, are re- 



