Succession al Relations of Vegetation. 



277 



The occurrence of the black spruce in this association and 

 its dominance in the older part of the bog, point to coming in 

 of the climax forest. 



In order to present the bog series in somewhat more detail 

 two other bogs will be described. On the rocky hill west of the 

 Markland, in the midst of a second growth of spruce is a bog 

 area which presents a noteworthy variation in its constituents 

 (Fig. 3). It is shallow and has developed on a solid rock surface. 

 The youngest part is represented by the Juncus-Sphagnum asso- 

 ciation. The substratum cover is made up of Sphagnum and 



Fig. 3. Area on top of cliff just east of Fig. 1. Showing spruce forest, alder thicket, and in the fore- 

 ground the Jancus-Sphagnum association. 



Polytrichum. Juncus effusus is scattered throughout. Yac- 

 cinium Yitis-Idaea, Cornus canadensis, Yaccinium pennsylvan- 

 icum, and Chiogenes hispidula with their various colored berries 

 are the most conspicuous forms in late summer. Of less impor- 

 tance, but scattered throughout, are Deschampsia caespitosa, 

 Rubus hispidus, Drosera rotundifolia, Calamagiostis canadensis, 

 Empetrum nigrum, Carex trisperma, Solidago uliginosa, Aspid- 

 ium cristatum, Aster junceus, A. acuminatus, Gnaphalium poly- 

 cephalum, Yaccinium oxycoccus, and Agiostis hyemalis. The 

 close relationship between this and the Calamagrostis-Sphagnum 

 association is evident. 



