PERIODICAL LITERATURE 



SOIL, WATER, AND CLIMATE 



G. A. Pearson, Director of the Eort Valley Ex- 

 Distribittio)i of i)erimental Station in Arizona, gives an excellent 

 Forest Types analysis of factors controlling the distribution of 

 forest types. He describes the physical charac- 

 teristics, including temperature, precipitation, wind and evaporation, 

 and soil factors. The articles are well written^ with complete tables 

 and diagrams. He gives a summary of the results for the following 

 types : Pinion- juniper, yellow pine, Douglas fir, Englemann spruce. 

 Pearson concludes "that the upper altitudinal range of all tree species 

 in this region is determined by low temperature, and the lower alti- 

 tudinal range by deficient moisture." T. S. W., Jr. 



Pearson, G. A. Factors Controlling the Distribution of Forest Types. 

 Ecology, Vol. 1, Nos. 3 and 4, 1920. 



MENSURATION, FINANCE, AND MANAGEMENT 



S. H. Howard criticizes the present method of 



Neiu Formula for regulating growth in India which requires stock 



Selection Forest taking, a knowledge of the time for trees to pass 



from one diameter class into another, and a 



knowledge of the percentage of survivals and he discards Von Mantel's 



formula which requires measuring the Avhole growing stock, usually 



impractical in India. 



Instead, he suggests the formula Yearly Yield = —, — . Where 



\' is volume of all trees in the forest over half the rotation age and 

 over, and R the rotation. The only data required are rotation, stock 

 taking of trees of half the rotation age and over, and the substitution 

 of diameter for half ihe rotation age. In subsequent issues of the 

 Indian Forester this formula is criticized because "no system can be 

 a system which does not only perpetuate the forest but which does not 

 also assure its progression towards a normal forest."' Replying to 

 this criticism, Howard states that nobody would use the Von Mantel 

 formula if data were available for a better calculation. He cites an 



.435 



