Ecology of the Cincinnati Region 
207 
particularly characteristic of high-level flood plains, both of rivers and 
small streams. Although this mixed mesophytic forest of the high-level 
flood plain differs from the erosion climax forest in many respects, it re¬ 
sembles it more closely than it resembles any other forest in the region. 
It is probably a fore-runner of that forest. 
The most complete successions are found on the inside of broad 
curves of the rivers. In such places, the rivers are essentially depositing 
streams, and their flood plains are constantly being built upward and 
outward. It is this constant addition to the flood plain, which permits 
of the gradual advance of flood plain vegetation. 
Even the mature flood plain forest is not always permanent. In 
the course of its wanderings on the flood plain, the river may destroy 
the land it has built up, and the trees that have grown upon it. On the 
Miami and Little Miami rivers this process is not slow. On under-cutting 
parts of the flood plain, many trees are destroyed each year. Across the 
river from the very complete flood plain formation shown in Hgs. S3~S7’ 
destruction of a mature stage of the fourth flood plain association is in 
progress. The trees lying in the water at the foot of the bank (iig. §8) 
illustrate the destructive work of this river. Erosion will very likely 
cease in this location before the whole of the flood plain has been de¬ 
stroyed. In this case, a new flood plain succession will commence on 
the new shore. Very often, parts of different successions are found 
upon the same flood plain. It is by this partial destruction of flood plains, 
that this condition is brought about. 
Beginning with the shore, the succession is a gradual and progres¬ 
sive one, culminating in the mixed forests of the high-level flood plains. 
VI. GENERAL CONCLUSIONS AND SUMMARY 
It has been shown that the plant formations of the Cincinnati region 
are closely related to its topography. The four principal topographic 
areas—uplands, slopes, flood‘plains, and terraces—are also, to a large 
extent, soil areas. Each exhibits its own plant associations, dependent 
as has been shown, primarily upon topography and its changes, and 
only secondarily, upon the soil. 
Soil influences may be overcome by topographic conditions. Dis¬ 
similar topographic forms, in the same soil are occupied by different 
plant associations. Similar topographic forms, in different soils, support 
