436 BOTANICAL GAZETTE [November 



This biotic influence has interrupted successions on every topo- 

 graphic type, chiefly in the following ways: cutting, with or with- 

 out burning, followed by cultivation, pasturing, or permitting the 

 area to become of economic value without assistance from man. 



This always retards the development of the area temporarily, 

 although it soon assumes the aspect of some previously established 

 type, modified by the interpolation of certain species, and it retains, 

 unless burned over, remnants of the previously established types, 

 especially among the herbs. These are of aid in the determination 

 of the history of the region in regard to the activities of men and 

 plants. 



The plants are listed here under the great groups, making it 

 possible to bear out Nichols' (3) statement that "species in groups 

 of comparatively recent evolutionary derivation are far more 



restricted in range than species in groups of more recent origin. 



?? 



The spermatophytes are again divided into trees, shrubs, and herbs, 

 to indicate more clearly the difference in biotic influence. 



Xerarch successions 



TRAP SLOPE 



There is an east face and a south face; the former belongs to 

 the Mount Tom Range, which has been a state reservation for 10 

 years, and which, it is hoped, will some day afford an opportunity 

 of seeing in this region a climax forest of some extent. 



There is no difference in the two slopes aside from the presence 

 on the south face of more ravines; in these ravines cutting has 

 ceased, as deforestation followed by fire has caused the drying up 

 of streams, leaving the ravines young topographically. The entire 

 region has been cut over within the last 25 years. At the top the 

 vegetation is again getting a foothold on the rock outcrop, except 

 at the edge, along the fault lines; here there is young tree growth, 

 in which can be found old stumps of red oak three feet in diameter, 

 indicating how far the region had progressed in its development. 



On the rock outcrop are found the following: 



Spermatophyta: Herbs. — Car ex rosea, Aquilegia canadensis, 

 Corydalis sempervirens, Arabis Drummondi, Saxijraga virginiensis, 

 Arctostaphylos Uva-ursi, Cardamine parviflora. 



