Nov., 1910.] A Cedar Bog in Central Ohio. 199 



lings of red maple and yellow poplar are close associates. The suc- 

 cession is virtually an indeterminate rejuvenation, that is, the habi- 

 tat still dominates the fonnation. The degree of stabilization is still 

 one to give expression to xerophytic forms. The physical conditions 

 are changing extremely slowly, remain unfavorable to invaders, 

 and tend to preserve many of the most important early vegetation 

 stages. The persistence and dominance of the cedar fomiation 

 in this latitude follows for these reasons, but partly also on accoiuit 

 of the predominance of the trees present; for the formation itself 

 must be considered as an essential active factor, in furnishing seeds, 

 and eliminating diversity. Largely, however, the dominance is an 

 adjustment to the available soil water content. A competition with 

 seedlings of deciduous trees other than the yellow poplar and red 

 maple does not seem to ensue although the light relation is 

 favorable. A relation of seed production to ecesis, i. e., to germi- 

 nation and establishment, is nowhere obvious. The various species 

 of deciduous trees have a larger seed production and more effective 

 dissemination contrivances, but so far as the actual number of 

 seedlings is concerned the relative absence of them suggests 

 some edaphic agency in selective operation. There is some sort of 

 correspondence in the arbor vitae, in plasticity of function, or in 

 habitat form, to the life relations of the soil. Definite conclusions, 

 however, can onl}^ be reached by experimental studies. The field 

 observations would indicate that the natiu-e of the primeval forest 

 of this region did not consist of a combination of trees such as now 

 exists on the drier areas described above. The deciduous arbo- 

 rescent facies in which the sequence is the development to the 

 deciduous climax forest, is at present decidedly a mixture, and 

 though a closed formation, yet one whose original members were 

 allied more to the northern cedar bogs. 



To Miss F. Detmers the writer is under many obligations for 

 aid in the identification of plants. 



|uj : L I 8 R rt K r 



rriS 



