FORESTRY SURVEY 229 



caused the more rapid erosion of that face of the ravine 

 before it was stabilized by vegetation. 



The vegetation in this part of the ravine was the same 

 as that of the mesophytic upland climax. 



C. Intermediate Region. — As the U-shaped ravine 

 merges into the V-shaped, there is a deepening of the 

 ravine by the gradual deepening of the stream bed and an 

 increase in the degree of the slope. With these changes 

 come a protection of the vegetation from wind, and a 

 decrease in light intensity, both of which result in reduced 

 transpiration, and gTeater retention of soil moisture. All 

 of these factors were effective in producing a forest which 

 represents the culmination of mesophytism for this entire 

 region. 



The chief tree species in this part of any of the ravines 

 were Acer saccliarum, Tilia americana, Quercus ruhra, 

 Fraxitiiis amcricana, Ostrija Hrginiana, Juniperus vir- 

 giniana, Carpinus caroJinidna, and Amelanchier cana- 

 densis. The first two were the dominant trees. Upland 

 species such as Quercus alba and Carya ovata are fre- 

 quently found in the ravine, but they are confined to the 

 upper edge of the deeper ravines. Carpinus caroHniana 

 was found in great abundance on the south-facing slope of 

 X. T. S, 23. Ostrya rirginiana was the dominant tree of 

 the lower stratum of the forest. The vegetation in all of 

 the ravines was luxuriant. The maples and lindens were 

 reproducing abundantly. 



The shrub species were Hamamelis virginiana, Corylus 

 amcricana, Tiburnum dentatum, Yihurniim acerifolium, 

 Viburnum lentago, Cornus circinata, and Gaylussacia 

 baccata. Hamamelis rirginiana was the dominant shrub 

 in all of the ravines. Gaylussacia baccata was found no- 

 where except along the upper edge of the north and east 

 slopes of Ravine 4 ( Xewhall ) , in X. T. 6, 47, and 50. 



The presence and frequency of the herbs Hepatica 

 acutUoba, MiteUa diphyUa, and Osmorliiza (sp.) on the 

 east- and north-facing slopes of the ravines was taken as 

 an indication of greater mesophytism on these slopes, 

 than on the south and west facing slopes. Mosses were 

 abundant in the deeper ravines. They were found most 



