298 



OHIO BIOLOGICAL SURVEY 



of southern and southeastern Ohio. On this account the determination 

 of the most profitable method of managing these hill lands is a matter 

 of very great importance to the welfare of the whole state and ought 

 on that account by all means to be taken up without delay. 



The progress of the deterioration of the land in this section is 

 difficult to follow in the fields where the vegetation is made up of 

 annuals and cultivation introduces many complications. But in the 

 woods, where the plants are perennial, the gradual change in the vege- 

 tation as the land deteriorates and the factors which are at work are 

 comparatively easy to observe. 



I'ig. LIS. West Bank of Ravine. Note Leaves and Young Growth. 



The cause may be sununed up in the one word exposure. Wherever 

 through thinning of the forest the wind is allowed to get in to the floor 

 of the forest, the vegetation quickly changes. In the underbrush, 

 plants characteristic of rich humus give place to others characteristic 

 of barren hillsides, and the seedlings which are to replace the forest 

 trees are of species of the same type. Thus the rich lowland forest is 

 rapidly giving way to the poor upland forest. The most characteristic 

 result of clearing the land is thus a descent of the upland vegetation 

 into the lowlands. 



The most striking examples of this descent of upland vegetation 

 occur in north and south ravines, where the best timber has been culled 

 out but the forest has not been cleared away. On the west slope of 

 such ravines the lowland forest usually maintains its ground, but on 



