Development of the Vegetation of New York State 167 
ing the northernmost tree species (“ stunted willows, birches 
and alders”’) and then the boreal coniferous forest species 
(“spruce, larch, hemlock and pines”). Third, the wave 
embracing temperate zone deciduous forests. Harshberger * 
(p. 203), ete., holds that ‘‘ several waves of plant migration 
may be coud ” (p. 204); namely, glacial vegetation, 
tundra, coniferous forests and, for eastern North America, 
the northward migration of the deciduous forest elements 
from “ the South Eastern center.” (p. 209.) 
With our attention fixed upon the matter of vegetation 
development upon the glaciated terrain of New York, we 
should observe in all this post-glacial migration and adjust- 
ment the sequence of vegetation in progressive adaptation to 
a changing substratum plus a changing climate, being in 
succession prevailingly tundra, boreal conifer forest, and, 
finally, on the whole, deciduous or mixed conifer and decid- 
uous forest of normal climax character based, so far as brief 
human history is concerned, on stable climatic conditions. 
That is the development of what for New York is the normal 
vegetation at its highest stage. 
2. Review of Development in Detail. 
This consisted in the construction of a story of develop- 
ment based on what we find happening in our vegetation to- 
day supported by obvious records of what it has done in the 
recent past. We found here that, viewing the water supply 
as the critical factor of the substratum, neither bare rock 
nor lake bottom (within the limits of sufficient light pene- 
tration) is a complete barrier to vegetation and that, starting 
from even these extremes, the course of events resulted in 
the building up of a substratum which, so far as water con- 
staney is concerned, approached the same (mesophytic) con- 
dition for each, and that finally the same, or approximately 
the same, plant society comes to occupy both situations as 
well as the soils which originally stood at various interme- 
1 Harshberger, J. W. Phytogeographic Survey of North America, 
1911. 
