DEPARTMENT OF BOTANICAL RESEARCH. 79 



tion which have a close resemblance, both floristically and vegetation- 

 ally, to communities below 1,000 feet. 



With the object of investigating some of the physical conditions 

 under which these vegetational phenomena exist, a preliminary line of 

 instrumentation was carried out in the summer of 1920. Eight sta- 

 tions were established for securing data on temperature, evaporation, 

 and soil moisture, and the localities were chosen so as to determine 

 the influence exerted on these conditions by altitude and bj^ distance 

 from the sea, both on the coastal and landward sides. 



The temperature data secured in July and August showed an increas- 

 ing daily range on passing inland from the fog belt, indicated lower 

 minima at 1,000 feet than at 5,000 feet, and maximum temperature 

 nearly the same at all elevations outside the fog belt. The evaporation 

 data show a doubling of the rate on passing 10 miles inland on the sea- 

 ward side of the range with only 600 feet increase of altitude and an 

 increase to 3.5 times the coastal rate at 200 feet elevation 23 miles from 

 the sea on the landward side of the mountains. The evaporation at 

 5,000 feet was found to be 50 per cent greater than at 1,000 feet and 

 4.5 times as great as in the fog belt. The soil moisture is low in July 

 and August in all localities, but shows a slight increase -^^th altitude 

 (6.9 per cent at 1,000 feet, 7.2 per cent at 3,000 feet, 14,1 per cent at 

 5,000 feet), while the soil moisture in the fog belt is no greater than at 

 the inland stations. 



The few data that have been secured up to this time appear to offer 

 ground for the explanation of the distinctive vegetational features of 

 the coastal belt and of the lack of greater altitudinal differences of vege- 

 tation. The increase in evaporating power of the air with increase of 

 altitude is in marked contrast to the conditions on the mountains of 

 the interior, where the reverse is true. The ratio of evaporation to 

 soil moisture, which has been found to be such a valuable index of the 

 general moisture conditions for plants, affords some interesting compari- 

 sons of the conditions in the Santa Lucia IMountains and in the pre- 

 viously investigated Santa Catalina Mountains, near Tucson. In the 

 former region the ratio rises from 3.5 at the coast to 14.1 at 5,000 feet, 

 while in the latter region it falls from 50.5 at the desert base to 3.3 in 

 the forests at 8,000 feet. So far as concerns the moisture relations of 

 the most arid months of the year, these ratios indicate a close identity 

 between the conditions under which the ^Monterey pine and its 

 associates are living on the California coast and those experienced by 

 the yellow pine and its associates in the mountains of Arizona. 



Ecology of the Stratid Vegetation of the Pacific Coast of North America, by 



William S. Cooper. 



During the summer of 1920 the work was confined to the continua- 

 tion of habitat and permanent quadrat studies begun in 1919 in the 

 vicinity of Monterey. 



