168 BOOKS AND CURRENT LITERATURE 



Pine and the Alpine meadow associations. The climatic conditions of 

 the three lower zones are recorded. The maximum temperature in 

 the Hudsonian zone in 1909 was 91° F.; in the Canadian, 97° F.; and 

 in the transition zone, 105° F. These figures stand in about the same 

 ratio as the temperature differences noted throughout the season. In 

 the Hudsonian zone the precipitation amounts to about 17 inches and 

 comes largely in spring, autumn and winter. This zone is well sup- 

 plied with water and, except in the case of seedlings, plants do not 

 suffer from drought. A higher evaporation rate was recorded in the 

 Hudsonian than in the Canadian zone. The results, it is stated, are 

 probably influenced by density of stand and it is not clear from the 

 presentation that it was possible to give the evaporimeters equal 

 exposures. In general, the conditions in the Hudsonian zone are more 

 favorable to forage production than in the lower zones, owing to the 

 lower temperature and heavier precipitation. Growth begins the last 

 week in June in the Hudsonian zone, about five weeks later than in 

 the Canadian and seven weeks later than in the Transition zone. The 

 resumption of growth in the same zone and at the same level varied 

 from 3 to 9 days due to slope, etc. 



Most of the grazing land occurs within the area characterized by the 

 White Bark Pine association. The trees occur in small dense clumps 

 and the forage grasses occupy the larger intervening area. Of the 

 grasses, the mountain bunch-grass, Festuca viridula, is by far the most 

 desirable and most abundant. Although not so distinguished in the 

 text, there are here two distinct associations, the White Bark Pine 

 association, which alternates sharply with an association composed 

 largely of mountain bunch-grass. 



The life historj^, including the period of growth, time of seed pro- 

 duction and seedling growth of each of the more important forage 

 species, is then presented. Even under the most favorable conditions 

 seedling production in the more desirable species is low. Undergraz- 

 ing conditions, low plant vigor, and the correlated late growth result 

 in decreased seed production and lessened seed vitality and, conse- 

 quently, in a greatly reduced stand of seedlings. Plants which are 

 deprived of their foliage early in the season do not reproduce. Seed- 

 lings develop rapidly, but many are lost during the spring following 

 seeding. During the dormant period few seedlings are lost except by 

 erosion. 



Extensive quadrat records of areas grazed continuously, protected 

 continuously, and grazed after the seed had been formed show that 



