THE DECIDUOUS FOREST CLIMAX. 



187 



The successional relations are even more evident in the arrangement of the 

 communities of Dismal Swamp (1901) : 



Salt marsh formation. 



Spartina stricta association. 



Juneus roemerianus association. 



Typha association. 



Spartina patens association. 



Baccharia-Hibiscus association. 

 Inland formations. 



Non-hydrophile formations; the wooded 

 or artificially deforested plains. 



Forest formations. 



Mixed forest. 



Pine barrens. 

 Cleared land formations (non-cultural). 



Arboreous (trees that have survived 

 the forest). 



Shrubby (thickets and hedges). 



Herbaceous. 

 Cultural formations. 



In the swamp forest, water stands upon the surface of the ground to a depth 

 of 1 to 3 feet during a great part of the year. Organic matter accumulates 

 upon the surface in enormous quantities and constitutes a Uving example of 

 that process of coal formation so active during the Carboniferous period, as 

 Lesquereux pointed out earlier. On the eastern margin of Lake Drummond 

 the stratum of black spongy humus is 10 feet or more deep. Sphagnum is 

 foimd with a large fern, Woodwardia, on low hummocks in the more open parts 

 of the wooded swamp. Sphagnum is abundant in these places and is often 

 associated with Eriophorum virginicum. It is not to be regarded as an 

 important humus builder in the Dismal Swamp, since it is always a secondary 

 member of the association. As a consequence, nothing resembling "climbing 

 bogs" has been observed in Dismal Swamp, as well as no replacement of the 

 tree growth by Sphagnetum; in fact. Sphagnum can make little headway in 

 the shade of the black-gum forest or in the canebrake. The author concludes 

 that there is no evidence that Lake Drummond was produced by lacustrine 

 peat formation, such as is typical of the great bogs of northern Europe, as 

 Lesquereux stated to be the case. 



Cowles (1901 : 109) has traced the development of the water sere under the 

 title of pond-swamp-prairie series, which he divides into undrained ponds and 

 swamps, and half-drained ponds and swamps: 



In the undrained pond, Chara, Nymphaea, Nuphar, and Utricidaria are 

 characteristic. Their remains shallow the water for the entrance of Carex, 

 Scirpus, Menyanthes, and Potentilla palustris, which form the next stage. 

 This is succeeded by the peat bog, dominated by Cassandra calyadata, 

 together with Vacdnium, Betula pumila, Alnus incana, and Salix Candida. 

 With the shrubs are associated Sphagnum, Sarracenia, Drosera, Calopogon, 

 Cypripedium, Eriophorum, Dulichium, etc. The Cassandra stage may be 

 followed by Larix and Thuja, these by Pinv^ strobus and P. banksiana, and 

 the pine associes by species of Quereus. In other ponds, Scirpus replaces the 

 water-lilies, and in tiirn yields to the sedge-land associes of sedges, grasses, and 

 scattered willows, with many herbs such as Viola, PotentiUa, Fragaria, Par- 

 nassia, Sabbatip, Gentiana, Gerardia, CastiUeia, Iris, Sisyrinchium, Hypoxis 

 Xyris. This is invaded by Salix, Cornus, Potentilla, and Hypericum as part 

 of the shrub stage. The margin of a peat-bog shows the tree stage to consist 

 of Nyssa sUvatica, Populus tremuloides, Ilex vertidllata, Pirus arbviifolia, 

 Betula papyri/era. Spiraea, Rubus, etc. The further course of the general suc- 

 cession is indicated by morainic swamps, characterized by Quereus macrocarpa, 

 bicolor, and coccinea, Acer rubrum, Ulmus americana, and Fraxinus americana. 

 This subclimax stage is ultimately supplanted by the mesophytic forest of 

 Acer and Fagus. 



