Development of the Vegetation of New York State 89 
or high forest stage has been reached in such situations as also 
it had on areas covered by great boulders or on areas of 
formerly bare rock. Now forest trees do not grow on bare 
rock or great boulders, nor do they spring up from the bottom 
of a lake (quite manifestly!) so that the conclusion is drawn 
that the effect of vegetation, augmented more or less etfec- 
tively by weathering, transport of sediment by wind and 
water and its deposition, is to build up the substratum, 
beginning at either extreme, 7. e., bare rock or lake bottom, 
to one common condition, a condition of soil structure and 
energy, of drainage and aeration, of sanitation and vigor- 
ously active soil organisms which supports a relatively per- 
manent or climax stage of vegetation. As a corallary to 
this, one would say that the vegetation history from either 
extreme to this climax point had been one of vegetation 
successions. For example, in the lake-bottom case, the suc- 
cessive vegetation stages might include (1) floating plants 
(microscopic forms, larger algae, duckweeds, ete.); (2) 
wholly submerged vegetation (pond weeds ete.); (3) 
floating-leaved plants (water lilies ete.) ; (4) marsh plants 
(sedges, bulrushes, cat-tail ete.); (5) marsh meadow 
(grasses and sedges, many annuals ete.) ; (6) marsh shrub 
or swamp shrub (willows, alders ete.); (7) swamp forest 
(red maple, black ash, elm, ete.) ; and finally (8) climax 
forest (maple, beech, birch, hemlock and white pine). 
It seems that the sequence of development hinges on the 
evolution of the substratum as one may say. In the build- 
ing up of this, whether from lake bottom or from bare ae? 
its character, viewed as plant habitat, changes constantly 7. e.. 
successively, so that each stage of vegetation — each eat 
association — as it contributes to this up-building and conse- 
quent modification destroys, if one may be permitted this 
manner of expression, its own chance of permanency and its 
place is invaded by plants of a different soil requirement ; and 
so the succession goes on until the soil condition becomes 
stable. What these modifications of the soil are that entail 
a succession of differently constituted plant associations I 
could not undertake to point out, but, certainly, one factor or 
