BOOK REVIEWS 



Conservation: The Long View 



Conservation of Renewable Natural Resources. A symposium by twelve 

 authors. The University of Pennsylvania Press, Philadelphia. Pp. 200. 1941. 

 $2.50. 



This interesting and important volume is divided into three sec- 

 tions, the first being: "The natural vegetation of the United States 

 as a guide to current agricultural and forestry practice." Following 

 a few introductory paragraphs by Raphael Zon, we wade into the 

 problem. Gustaf A. Pearson discusses "What forest trees tell about 

 climate and soil," and Homer L. Shantz discourses on "The original 

 desert shrub vegetation of the United States as a guide to present- 

 da}^ agricultural practice." These two, as we might expect, are 

 excellent journeyman accounts of the problem, even if somewhat 

 static in their viewpoint. It remains for William S. Cooper, the 

 ecologist, to approach the problem in a dynamic manner in his 

 "Man's use and abuse of native vegetation : the lessons of the past 

 and the prospects for the future." 



The second section, "Climatic cycles in relation to the theory 

 and practice of conservation," has its quartet of authors. A. E. 

 Douglass, as one would imagine, gives a rather lengthy discussion 

 of "Dendrochronology and the studies in 'Cyclics.' " It is perhaps 

 overburdened with methods, but is a good review of this work. The 

 chapter by Charles G. Abbot on "Periodicities in solar variation 

 reflected in weather," while brief, reiterates our knowledge that 

 "weather" does come in cycles of varying length. Paul B. Sears, 

 under the topic of "Conservation and changing environment," 

 emphasizes perhaps as much as any of the authors that if man is 

 to control his environment, if he is to hold the soil at a necessary 

 level of productivity, he must first learn to control the greatest 

 despoiler of the land — man himself. But he further points out that 

 agricultural activities, even under the best of conditions, introduce 

 a chain of events which make the necessary conservation of soil 

 very difficult. 



The closing chapter of this section, "Climatic pulsations and 

 an ozone hypothesis of libraries and history," is by Ellsworth Hunt- 

 ington. Although the major portion of the chapter is taken up 

 with an exposition of his "ozone hypothesis," proving only that 



170 



