26 



BOTANICAL GAZETTE 



[JULY 



surprisingly uniform in depth, rarely exceeding lo cm. in thickness. 

 The sand below this layer has been discolored for several decimeters 

 and its chemical content is plainly affected by materials leached 

 down from the humus above. 



Moisture content.— The moisture content of the soil varies with 

 the location and the character of the substratum, as is shown in 

 table I. The 7 cm. samples were usually taken in the sand just 

 below the lower edge of the humus, as it was thought that a centi- 

 meter of depth more or less would have less significance than an 

 indeterminable admixture of humus. 



TABLE I 



ECOLOGY 



Climax forest. — The whole region, including at least part of 

 the moving area, was originally covered by a heavy climax forest, 

 which is still practically untouched in the southern tip and along 

 most of the eastern edge of the dunes. The level ground on the 

 Bar has largely been cleared, and is covered with second growth 

 of forest trees and clearing pioneers, where not occupied by summer 

 cottages. The climax forest is composed of beech, maple, and 

 hemlock, with much yellow birch. The trees are tall and slender, 

 with close stand and very little undergrowth where undisturbed. 

 Occasional specimens of Quercus rubra, Pinus Strobus, and P. 

 resinosa are found. Among the shrubs Acer spicatum, about at 

 the southern limit of its range. Viburnum acerifolium, and Taxus 

 canadensis are conspicuous. Characteristic species in the under- 

 growth are Aralia nudicaulis, A. racemosa, Streptopus roseus, 

 Clintonia borealis, Maianthemum canadense, Linnaea borealis, and 



