TRbooora 
JOURNAL OF 
THE NEW ENGLAND BOTANICAL CLUB 
Vol. 22. March, 1920. No. 255. 
SOIL TESTS OF ERICACEAE AND OTHER REACTION-SENSI- 
TIVE FAMILIES IN NORTHERN VERMONT 
AND NEW HAMPSHIRE 
Epcar T. WHERRY 
Tuae relative importance of physical and chemical features of soils 
in determining the distribution of vegetation is the subject of consider- 
able difference of opinion. Some have reached the conclusion that 
physical factors, such as porosity and water content, are more signifi- 
cant than chemical factors, such as the presence of abundant lime or 
of excessive acidic substances; others consider the chemical nature of 
the soil, and accordingly the nature of the rock from which it is de- 
rived, to be of fundamental importance. An illustration of the appli- 
cation of these two viewpoints in explaining the distribution of two 
northern coniferous trees has recently been published by Fernald.! 
The physical features proved in these cases entirely inadequate to 
account for the observed relationships, whereas the geology, and the 
resultant chemical properties of the soil, show so close a correlation 
with the areas occupied by the species in question, that no one ap- 
proaching the subject with open mind could fail to recognize therein 
the dominant factor in their distribution. 
The writer became interested in this subject several years ago, 
while engaged in geological field work in Pennsylvania, through ob- 
serving that relationships existed between the native plants and the 
underlying rock formations; but at that time there was no simple 
method available to determine whether the effect was chiefly physi- 
1Fernald, M. L. Lithological factors limiting the ranges of Pinus Banksiana 
and Thuja occidentalis. Ruopvora xxi. 41 (1919). 
