3?6 A. G. Tansley. 
ever become oakwood unless they are actually overwhelmed by 
sand is doubtful. 
The black oakwood is often invaded by other species of 
oak, such as Quercns alba and Q. rubra, and thus passes 
to a mixed oakwood association with Till a americana, etc., and 
many more shade-loving forms. Eventually this may he replaced, 
as is admirably seen at Sawyer, Michigan, by the typical shade 
trees of the north-eastern United States, dominated by the beech 
(Fagns grandifolia) and the sugar maple (Acer saccharnm), with 
scattered examples or local groves of Tsuga canadensis, and such 
characteristic trees and shrubs as Liriodendron tillipifera, the papaw 
(Asimina triloba), the witch hazel ( Hainamelis virginica) and the 
spice bush (Benzoin cestivale), etc., though some of these may 
occur somewhat earlier in the succession. The beech-maple 
forest shelters a typical shade-loving vegetation, with the beautiful 
and characteristic shade fern Adiantum pedatnm, Polysticlium 
acrostichoides, Aspidinin marginale and A. spinulosum, and 
numerous angiospermous shade-herbs. There can be no doubt 
of the essential identity of this climax association of the sand- 
dune succession with the typical climax beech-maple forest of 
the neighbourhood as developed on clay soils. 
Such a forest on glacial clay was visited near Three Oaks, 
Michigan, and though some of the species differ from those of the 
beech-maple forest on old sand-dunes, the essential identity of the 
vegetation in the two cases cannot be questioned. 
Mr. Warren’s Beech-Maple Forest. 
This beech-maple forest on clay is a magnificent specimen of 
virgin deciduous forest. The beeches and maples are about equal 
in numbers, and their tall finely-shaped trunks tower to a great 
height. One large maple measures 15f feet in circumference 2 feet 
from the ground. The shade cast is dense, and the evaporating 
power of the air very low. There is a typical shade ground 
vegetation with abundant ferns and many humus plants. The 
free rejuvenation of the dominant trees is a marked feature, a large 
proportion of the woody undergrowth being formed of young beeches 
and maples. In some places there is, I think, some evidence of 
differentiation of the ground vegetation by the local occurrence of 
more sandy soil. Round the shallow pools left in old “oxbows ” of 
the river, such trees as Platanns occidentalis and the “ soft” maple 
(Acer saccharnm) occur. 
This fragment of beech-maple forest is one of the few rem¬ 
nants of the magnificent deciduous forest that once covered nearly 
