270 SUCCESSION IN EUBASIA. 



Steiner (1912 : 105) has made an incidental study of the successional zones 

 about Lake Lugano in Switzerland: 



The rocky lake-shores have no coherent covering, but are characterized by 

 scattered plants of Chora, Schoenopledus lacustris, Phragmites, and rarely Pota- 

 mogeton perfolicdus or Myriophyllum spicatum. Gravelly shores show the fol- 

 lowing zones: (1) Characetum, (2) Potametum, (3) Schoenoplectetum, (4:)Phrag- 

 mitetum, while the series of communities on muddy shores is (1) Characetum, 

 (2) Potametum, (3) Nupharetum, (4) Schoenoplectetum, (5) PhragmiMum, 

 (6) Magnocaricetum. The author indicates a munber of combinations in 

 which the stages occur in various localities. In some cases, Phragmites alone 

 may be present, or Phragmites and Schoenopledus. In the great majority of 

 instances, Phragmitetum is associated with two other communities. 



Siegrist (1913) has treated at length the topographic production of new 

 areas on the flood-plain and in the cvu-rent of the river Aare in Switzerland, and 

 has traced the course of succession upon them: 



The serai development in quiet water is as follows: (1) Aquatic community, 

 (2) reed swamp, (3) Magnocaricetum, (4) Salix-Alnus woodland (locally 

 meadow may occur), (5) meadow forest, (6) mesophytic mixed forest. In 

 rapidly flowing water the stages are the following: (1) algae and mosses, 

 (2) Agrostidetum, (3) Calamngrostidetum, (4) meadow forest, (5) mixed forest. 

 On newly formed sand-bars or islands, the meadow forest may develop directly, 

 or the pioneer stage may consist of willows, followed by alder and terminating 

 in the mixed forest. When the area consists of bare gravel without a sand or 

 humus cover, the initial stage is an open community of herbs. This may be 

 followed directly by a pine forest or meadow forest, both of which terminate 

 in the mixed forest, or it may be succeeded by a Hippophastum, which in turn 

 yields to the pines or to mixed forest. 



RUSSIA. 



Tanfiljew (1890) has described the formation of swamps by the shallowing 

 of water: 



This begins with Menyanthes, Comarum, Cicuta, Carex, Iris, Beckmannia, 

 and Glyceria, which are followed by Sphagnum with its usual associates. The 

 filling of lakes causes a rise of the water-level, the consequent flooding of the 

 banks, and the destruction of the adjacent trees. Sphagnum develops only 

 in non-calcareous water; in hard water its r61e is taken by Hypnum. Swamps 

 may be produced from ponds and lakes by sedges and grasses without the 

 activity of mosses. The author distinguishes four causes of swamping: 

 (1) the formation of impervious " ortstein," (2) flooding, (3) activity of springs, 

 (4) the entrance of water-holding mosses. 



Korschinsky (1891) flnds in the oak forests of Russia that reproduction is 

 almost completely absent, owing to the fact that the oak is an intolerant 

 species: 



The maintenance of an oak forest takes place only by the fall of older trees, 

 which permits the entrance of the necessary light. As a rule, however, more 

 tolerant species, such as the linden, beech, spruce, and fir, invade before this 

 happens, and reproduce readily. As a consequence, the oaks drop out through 

 death and accident, and their place is taken by a new group of tolerant forms. 

 A mixed forest, then, is never static, but represents a transition stage to the 

 final climax association. The author regards the sequence of forest species 

 in peat-beds as further proof of this process. He cites the investigations of 



