﻿Nichols: The vegetation of Connecticut 215 



climatic changes, the more vigorous southern species gained the 

 upper hand, so that spruce and fir have largely been eliminated 

 from this region. 



In the present connection the discussion set forth in the pre- 

 ceding paragraph is of course significant only as it bears on the 

 question as to the origin of Connecticut bog vegetation. In the 

 opinion of the writer the answer to this question may be stated 

 somewhat as follows. From the above discussion it seems fairly 

 certain that within very recent geological time the vegetation of 

 this region has been quite like that of northern Cape Breton 

 Island today, i. e., the upland forests included a mixture of broad- 

 leaf and coniferous forest types and bog vegetation was common in 

 all swamps. As the conquest of the region by the southern types 

 of vegetation progressed further, the coniferous type was first 

 vanquished on the uplands, since here environmental conditions 

 proved most congenial to the invaders. It was not, perhaps, 

 until these uplands had become pretty completely occupied that 

 the last strongholds of the northern plants — the swamps — ^were 

 stormed.* The northern vegetation in spring swamps was first 

 to succumb, since soil conditions here proved quite suitable for 

 certain of the southern invaders. Similarly the northern vegeta- 

 tion in most lake swamps was gradually replaced by southern 

 types. But the conquest of some of these lake swamps proved a 

 difficult undertaking, owing to the peculiar soil conditions which 

 have been described in connection with the discussion of bog 

 xerophytism. For to these adverse soil conditions the northern 

 defenders proved singularly well adapted — so well adapted, in 

 fact, that many of these isolated plant communities still survive 

 the siege. A bog, therefore, is to be regarded as a relict swamp 

 type whose vegetation represents vestigial remnants of a more 

 northern type of flora which has been much more widely repre- 

 sented in this region within very recent geological time. It does not, 

 however, seem advisable to assume that "the habitat dates back 



Cape Breton Island afifords an instructive analogy. Four of the n 

 Connecticut swamp trees, viz.. Acer rubrum, Ulmus americana, 



