RELATION OF CONDITIONS TO HABITAT DISTINCTIONS. 



49 



The average daily range of temperature is greater at Cinchona and 

 in the Ruinate than it is in any of the forested areas. The Ruinate 

 record was secured in an exceptionally clear and warm week, and its 

 daily mean range probably represents the maximum for the entire 

 region. The daily range at Sir John Peak, 11.3° F., is higher than for 

 any other forested habitat, as might be expected. The Windward 

 Ravines exhibit the lowest ranges of temperature, and those of the 

 Slope, the Ridge, and the forest canopy are greater and of about the 

 same order of magnitude. 



Table 11. — Recapitulation of temperature data for different habitats. 



Such slight temperature differences are without significance in the 

 differentiation of the habitats within the rain-forest, and are of impor- 

 tance only in so far as they operate conjointly with other factors in 

 affecting transpiration, growth, and other complex activities of plants. 

 The low nocturnal winter temperatures of the highest peaks are suffi- 

 ciently different from those of the slopes at 4,500 to 5,600 feet to be of 

 significance in the limitation of species, as has already been suggested. 

 In general, however, the role of temperature as a differential climatic 

 factor in the Blue Mountain Region is an extremely unimportant one. 



SOIL TEMPERATURE. 



Six weekly graphs of soil temperature have been selected from a 

 larger number as exhibiting the most striking differences in this remark- 

 ably uniform factor (plates 22 to 28). There is a close correspondence 

 between the mean temperatures of the soil under the open sod of the 

 lawn at Cinchona, in a coffee field with southerly slope and a light 

 covering of weeds, and in the Ruinate (table 12). The substratum in 

 Windward Ravines possesses a soil temperature nearly 10° F. lower 

 than those just mentioned, and the soil on the summit of Sir John 

 Peak; in the Ridge type of forest, is closely like that of the Windward 



