DEPARTMENT OF BOTANICAL RESEARCH. 79 



ridges play only a minor part in bringing about a differentiation of 

 the chaparral. Differences of slope exposure may determine the 

 presence of the composition of chaparral in all regions except the most 

 arid interior hills, where there is none at all, and the hills facing 

 immediately on the sea, where it is very uniform. Differences of slope 

 gradient, with the accompanying differences of soil depth, frequently 

 appear to condition the occurrence of chaparral, gentle slopes with 

 deep soil being occupied by grassland, while the steeper or rocky slopes 

 are covered by chaparral. Differences in the character of the soil 

 have been found to accompany differences in the composition of the 

 chaparral, but the significance of a given relation changes on going 

 from the seaward to the landward side, and to some extent on going 

 from lower to higher elevations. Chaparral is absent from the nearly 

 level summits of many hills, even in close proximity to the sea, although 

 the slopes of the same hills are covered and the sunilar sunomits of 

 adjacent hills are also covered. At higher elevations the level summits 

 are covered by chaparral, but the south and west slopes are often 

 occupied by areas of grassland. Immediately south of Monterey the 

 hills are covered with chaparral from the beach to their upper sunmiits. 

 From Cayucos to the mouth of San Carpophoro Creek the hills 

 adjacent to the ocean are grass-clad and devoid of chaparral, except 

 on steep, rocky, landward slopes. An elucidation of the many eco- 

 logical problems presented by the chaparral will require much more 

 extended and intensive work. 



The Santa Lucia Mountain region embraces, chiefly or entirely, 

 the distributional areas of Pinus radiata, Abies venusta, Cupressus 

 macrocarpa. and Cupressus goveniana, as well as the southernmost 

 localities of Sequoia sempervirens and a number of its associates. An 

 examination has been made of the habitat characteristics of these 

 plants, with particular reference to Pinus radiata. This tree is found 

 only at the northern and southern extremities of the Santa Lucias, 

 in spite of the existence of apparently favorable habitats in the inter- 

 vening region. In the vicinity of Cambria and San Simeon it exhibits 

 a greater catholicity of habitat requirements than in the vicinity of 

 Monterey and less dependence upon proximity to the sea. While 

 geomorphic movements undoubtedly lie at the basis of the present 

 distributional features, there is offered, nevertheless, a fruitful problem 

 for investigation with respect to the factors controlling the reproduc- 

 tion and life-histories of all these endemic forms. 



A Soil-Temperature Survey of the United States and Canada, hy Forrest Shreve. 



In 1916 the Ecological Society of America appointed a committee 

 consisting of Forrest Shreve, chairman, and Dr. Alfred E. Cameron, 

 of the Dominion Entomological Service of Canada, charged with 

 carrying out preliminary soil survey of the United States and Canada. 



