210 
Ohio Biological Survey 
The typical flood plain succession is a direct result of stream action. 
Changing topography is the chief cause of the progress of the suc¬ 
cession. 
All successions in the region, whether xerarch or hydrarch, in 
whatever topographic situation they may be, are progressing toward a 
mesophytic forest. The relatively short successions on a topography 
as yet unchanging, and the long and varied successions on ever chang¬ 
ing topographic forms, all lead to a mesophytic forest—a climax forest. 
The climax mesophytic forest exists in two distinct forms. One is the 
beech forest of the uplands and filled valleys, the forest developed on an 
unchanged or very youthful topography. The climax of the vegetative 
cycle precedes, or accompanies the initiation of the erosion cycle. This 
beech forest is the pre-erosion climax. 
The second form of the climax forest is the mixed mesophytic forest 
of gentle slopes. All long successions dependent on topographic changes 
lead to this forest. The succession in ravines, the successions in progress 
on flood plains, both end in a mixed mesophytic forest. Both depend on 
topographic change, the first on stream degradation, the second on stream 
aggradation. The climax of these vegetative cycles follows a period of 
erosive activity. It comes within an erosion cycle. This mixed meso¬ 
phytic forest is the erosion climax. 
The pre-erosion climax forest of the Cincinnati region resembles 
the beech forests of northern Ohio and of Michigan. Its closest affinities 
are northward. The erosion climax forest resembles the deciduous forest 
of the Southern Appalachians. It is poorer in variety of trees, but it has 
much in common with the southern forest. Northern and southern for¬ 
est types here occur side by side. 
The pre-erosion climax forest is temporary. It can endure only as 
long as the pre-erosion topography. The erosion climax forest, a mixed 
mesophytic forest, which results after, though not at the end of topo¬ 
graphic changes, represents more truly the climax forest of the region. 
