NOTES 887 



northern hardwood region is good. The differentiation between these 

 two regions is, he says, due to differences in soil. Whether or not the 

 soil differences are merely due to differences in weathering, as he ap- 

 pears to assume, is another matter. 



Hutchinson's errors in tree ranges have been sifted out by Fernald 

 in his paper on "Lithological Factors." ^ These errors are chiefly due 

 to Hutchinson's acceptance of the theory that "the composition of the 

 rock from which any soil may be derived seldom acts in a limiting 

 capacity with respect to the species which that soil may support." This 

 dogma, unfortunately, all too generally accepted by ecologists, leads 

 Hutchinson into error, particularly in the ranges of Jack pine {Pinus 

 baiiksiana) and white cedar (Thuja occidentalis). As a natural cor- 

 ollary, it makes him give mistaken explanations of so-called "irregu- 

 larities" in these ranges — "irregularities" which become perfectly reg- 

 ular when one recognizes that jack pine does not grow on limestone 

 formations, and that white cedar is largely confined to calcareous soils. 



On the whole the paper contains much of interest. It would be a 

 mistake to condemn it entirely because of a false viewpoint toward one 

 of the factors w^hich it considers. The specific requirements of forest 

 trees for temperature, water, soil, and the other factors which control 

 the life of the forest must be studied as a basis for sound silvicultural 

 practice. Hutchinson has made a beginning in collecting some of this 

 important material. As such, and for the stimulus which his work will 

 give to further studies along this line, his paper is of value. 



Barringtox Moork. 



Soil Requirements of Jack Pine and White Cedar ^ 



Fernald's paper, "Lithological factors limiting the ranges of Pinus 

 banksiana and Thuja occidentalis." together, with his paper on "The 

 contrast in the Floras of Eastern and Western Newfoundland" ^ — a 

 contrast due to the limestone in western and acidic rocks in eastern 

 Newfoundland — marks a turning point in ecology. Hitherto most 

 studies of the factors controlling vegetation have been started on the 

 assumption that climate dominates, almost to the exclusion of all other 

 influences save fire. I am classing topography and elevation under 



*M. L. Fernald: "Lithological factors limiting the ranges of Pinus banksiana 

 and Thuja occidentalis." Rhodora, Vol. 21. No. 243, pp. 41-67, March, 1919, 



* M. L. Fernald: "Lithological factors limiting the ranges of Pinus banksiana 

 and Thuja occidentalis." Rhodora, Vol. 21. No. 243, pp. 41-67, March, 1919. 



" M. L. Fernald : "The contrast in the floras of eastern and western Newfound- 

 land." Am. Jonr. Bot., Vol. 5, No. 5, pp. 237-247. 1918. 



