1914] ROBERTS— PLANT SUCCESSIONS OF HOLYOKE RANGE 441 



There is an indication of the hemlock coming in twice in the 

 succession, first in the early stages of the ravines as a temporary 

 climax, and later at the climatic climax of the region as shown in 

 the successions on the north talus slope. The white pine does much 

 the same thing, forming a temporary climax on the east-facing 

 cliffs and a temporary climax on the lake bottom sands, which are 



at the foot of the talus slope. There are many 



remains 



lished for some time. It looks as if the region had reached the pine 

 stage many times; now conditions are such that the region is 

 advancing a stage and oaks and chestnut are beginning to get a 

 foothold. The accompanying diagram in a general way indicates 

 the natural successions and the effect of repeated deforestation. 



Hydrarch successions 



RAVINE SUCCESSIONS 



The ravines parallel to the Mount Holyoke Range and the 

 ravines on the south trap face of Mount Holyoke are to be con- 

 sidered. 



The parallel ravines on Mount Tom have been formed by differ- 

 ential weathering and never had any streams in them. The rock 

 sides are perpendicular and have no vegetation but lichens, except 

 for a few crevice plants. The base of the ravine is covered with 

 trap chips among which vines and a few shrubs are getting a foot- 

 hold. 



The ravines on the trap slope are no longer being actively cut. 



many 



streams, so that there are found many 



r but old floristically. In the early spring the meltin 

 n down these ravines. Other ravines are older topogra 



same floristically 



the same 



from 



be found Tsuga canadensis, Pinus Strobus, Juglans einerea, Tilia 

 americana, Betula lenta, B. lutea, Castanea dentata, Acer saccharum, 

 and some very young Fagus grandifolia. Time enough apparently 



