Hill: Penobscot Vegetation 435 



and vegetation is forced to make a fresh start. Blueberry 

 barrens, maintained by frequently burning over a locality, 

 are of increasing prominence. After a hardwood is cut off 

 it is followed by either a sprout growth or by conifers. A 

 coniferous forest is usually succeeded by a bramble stage 

 and a birch-poplar wood before conifers again return. 



Succession in lowlands is similar to that in other regions, 

 several different types occurring: well-drained lakes and 

 lake-swamps with stages leading to a swamp forest, or rare- 

 ly a cedar swamp, as a physiographic climax; undrained 

 ponds in which a bog forest constitutes a physiographic cli- 

 max ; spring swamps, either open swamps or wet meadows, 

 which ultimately may be covered by a swamp forest; and 

 poorly-drained areas, which show intermediate conditions 

 between swamps, bogs and uplands. The vegetation of low- 

 lands along the shore, — barrier beach ponds, salt and brack- 

 ish marshes — is like that of similar areas elsewhere. 



VII. BIBLIOGRAPHY 



1. Adams, C. C. Postglacial origin and migrations of 



the life of the northeastern United States. Jour. 

 Geog. 1: 303-310. f. 1. 1902. 



2. Bray, W. L. The development of the vegetation of 



New York State. N. Y. State Coll. For. Tech. 

 Publ. 3. pp. 1-186. f. 1-52 and map. 1915. 



3. Chittenden, A. K. Forest conditions of northern 



New Hampshire. V. S. Dept. Agr. Bur. For. Bull. 

 55. pp. 1-100. pi. 1-7 and maps 1-2. 1905. 



4. Cooper, W. S. The climax forest of Isle Royale, 



Lake Superior and its development. Bot. Gaz. 55: 

 1-44, 115-140, 189-235. f. 1-55 and map. 1913. 



5. Dana, S. T. Paper birch in the northeast. U. S. 



Dept. Agr. For. Serv. Circ. 163. pp. 1-37 and f. 1 

 and map. 1909. 



