S3 CLAYBERG -UPLAND SOCIETIES 1920] 



hemlock type seen, probably because farthest from the shore and 

 most sheltered from the wind. The presence of many balsam and 

 some oak seedlings, and the absence of sugar maple, make the next 

 stage uncertain. Dense thickets of Corylus rostrata Ait. and much 

 Taxus are characteristic. The hemlock on a Post-Nipissing level 

 west of Harbor Springs is similar, but is mixed with Abies balsamea 

 .Mill, and Thuja occidenlalis L. The Algonquin cliff west of Petos- 

 key in several places bears large hemlock stumps of uniform (71- 

 75 cm.) diameter, indicating that it w r as once largely occupied by 

 a fine hemlock forest. The trees were cut sometime ago, for the 

 secondary forest is nearly grown (average diameter 25 cm.), being 

 beech, sugar maple, and Bctula lutea Michx. f. A constant associ- 

 ate on open banks and cliffs is Polytrichum commune L., taking here 

 as prominent a place as Taxus canadensis does in the level and denser 

 part of the forest. 



Climax forest 



Seriation 



The composition of the climax primary forest of the region has 

 long been considered constant from the time the maple and beech 

 reach dominance and respectable age. This is true floristically, 

 but not ecologically or physiologically; for a climax formation 

 is static in species, but dynamic as to individuals. Analysis of 

 sufficient territory show r s the forest to be more or less of a patch- 

 work composed of trees in varying stages of development. 



Cooper (4) found the climax forest he studied to be a "complex 

 of windfall areas of differing ages, the youngest made up of dense 

 clumps of small trees, and the oldest containing a few mature trees 

 with little or no young growth beneath, those of a single group being 

 approximately even-aged. This mosaic or patchwork changes 

 kaleidoscopically through long time spaces, but the forest as a whole 

 remains the same, changes in various parts balancing each other." 

 His studies were of a coniferous forest. The climax here is decidu- 

 ous, so differences are to be expected. The forest floor is lighter and 

 the next generation starts sooner in the case of the maple-beech 

 forest. The patches observed in the climax forest of this region are 

 too large to consider as the result of one tree fall. Further, they 



