FORESTRY SURVEY 233 



Fig. 4. Qucrcus ellipsoidaJis var. coronaria is the tree in the fore- 

 gromid. Qucrcus elUpsoidalis and some of its varieties, 

 which characterize the hydra rch-mesophy tic association, form 

 pure stands in plac-es (N. T. 7, 9). 



Fig. 5. Hydrarch succession of associations from the iindrained low- 

 land to the upland. 



Fig. 6. Reproducing upland mesophytic climax forest north of 

 Eaviue 4 (Xewhallt in which Quercus alba and Qucrcus rubra 

 are the dominant trees. Note the abundance of saplings and 

 shubl>ery. and also the heavy mulch of leaves in the under- 

 growth. 



Fig. 7. Eroding morainic clay bluff near Ravine 5, as it appeared in 

 1900, showing a steep angle of slope and absence of vegeta- 

 tion. After Cowles. 



Fig. S. Lake bluff (same as in Fig. 7) in 191S. The more gentle 

 slope shows the effect of erosion between the years 1900 and 

 191S. The vegetation (mostly planted) is bringing about the 

 stabilization of the lake bluff. 



Fig. 9. Populus-shrub assoc-iation of the lake bluff. Shrubs are dom- 

 inant and trees are of small size. The vegetation is sero- 

 phytic and sparse, but fairly uniformm in its distribution. 



Fig. 10. Jimipertis-shrub association in which Junipcrus communis, 

 Junipcrus vir{/inia)W and Ostrya virginiana are the dominant 

 species. Additional shrub species are also abimdant. The 

 vegetation is more dense than in the Populus-shrub associa- 

 tion. 



Fig. 11. Young specimens of Piiius St rob us in Juniperus-shnib associ- 

 ation. 



Fig. 12. Lake bluff (as it appeared in 19001 south of Ravine 4 (New- 

 hall I in its early stage of stabilization. After Cowles. 



Fig. 13. Lake bluff (same as in Fig. 12) in 191S, showing rapidity of 

 vegetational development after stabilization of the soil has 

 been completed. 



Fig. 14. Reproducing upland mesophytic climax forest on the lake 

 bluff' north of Ravine 4 (Xewhall) the aspect of which ap- 

 proximates that of a virgin forest. Note the size of the dom- 

 inant trees (Qucrcus alba and Qucrcus rubra), and the 

 dense undergrowth of saplings and shrubs. The angle of 

 slope is less than in other lake bluff associations. 



Fig. 15. Mouth of ravine (in 1900i in the initial stage of the ravine, 

 exclusion of vegetation from its faces. After Cowles. 



Fig. 16. Mouth of Ravine 5 in 191S which shows a widening of the 

 mouth due to erosion and partial stabilization of the slope by 

 the planting of grasses and black locust. 



Fig. 17. Mouth of Ravine 3, with Populus-shrub and Juniperus-shrub 

 types of vegetation on its faces. For inland extension of this 

 type of vegetation see Fig. IS. 



Fig. 18. Intermediate area (in the foreground) of a mature ravine 

 (Ravine 3t showing the steep north -facing slope (to right) 

 and slanting trees which indicate the beginning of lateral 

 erosion in this mesophytic climax forest. Acer saccharum, 

 Tilia americaua and Fraxinus amcricanci are the dominant 

 species. Note jimipers in background at mouth of ravine. 



