ECOLOGICAL SUCCESSION. 6 1 



II. LOCALITIES OF STUDY. 



The forest development series might be variously divided for 

 purposes of study. The number of stages and variations that 

 might be recognized is considerable. For the purpose just out- 

 lined we have selected five stages. Transition areas are present, 

 but only the most important two, namely those between the 

 first and second and the second and third, have been noted. 

 The stages considered are (i) Cottonwood stage; (1-2) the transi- 

 tion between the cottonwoods and the pines; (2) pine stage; 

 (2-3) transition between the pine and oak or mixed pines and 

 oaks together with open places in the oak areas; (3) black oak 

 stage; (4) red oak stage the red oak associated with the black 

 oak and white oak in the earlier stages and with the shag bark 

 hickory in the later stages; (5) the beech and maple stage. 



i. Cottonwood Stage. 



The cottonwood (Populus deltoides) areas are located near the 

 lake shore and the sand is always more or less shifting and rarely 

 with more than traces of humus. The cottonwoods are usually 

 small trees, scattered over the beach ridge, or the lakeward side 

 of the shore dunes as the case may be. Between them are 

 widely scattered bunches of grasses of which Calamovilfa longi- 

 folia is the most characteristic species and Ammophila arenaria 

 usually common. Scattered individuals of Artemisia canadensis 

 also occur. The shrubs, which are still more scattered or local, 

 are the beach plum (Primus pumila} and some of the xerophytic 

 willow r s (Salix glaiicophylla). 



All localities are indicated on the map, p. 62, by letters used as 

 designated below. Two principal cottonwood stations have 

 been studied. One lies to the east, lA, and one to the west, iB, 

 of Pine, Ind. At these points the cottonwood area is about ten 

 rods wide and reaches inland just beyond the crest of the ridge 

 where the plants of transition come in. (For the arrangemenc of 

 ridges see Fig. i, p. 137, of "Ecological Succession II.") Two 

 other less fully studied areas have been visited frequently, viz., 

 iC, at Miller, Ind., and iD, at Dune Park. (See map.) 



