26 College of Forestry 
tion of species supplants the pioneer one. With the further 
building up of the lake bed to very shallow water or marsh 
conditions, there follows an association of species capable of 
raising their stems and leaves above water and of sustaining 
them against the stress of rain and wind. The root system 
and often rhizomes build tussocks (like water-arum, Carex 
stricta, royal fern, ete.) or mats (like cat-tail flag and certain 
sedges) thus firming the miry uncompacted mud. Yearly ae- 
cumulations of the dead members of this now quite bulky 
vegetation the more rapidly builds up a firmer soil to or 
above the water level and this condition invites an invasion 
of marsh-meadow vegetation, a yet more complex and varied 
society, to be followed later by a marsh-shrub association of 
alder, willows, buttonbush, sweet gale; later by swamp forest 
of soft maple, elm, black ash, ete., with a ground stratum of 
swamp fern, swamp shrubs, numerous herbaceous plants, and 
other growth forms among seed-plants, mosses, liverworts, 
lichens, wood fungi, ete. In the end when this substratum 
has been further built up, the soil well drained and aerated so 
that the organic stuff is in position to be reduced to leaf mold, 
the permanent or climax or high forest society becomes es- 
tablished. This is the most highly differentiated association 
of all; that is to say, it is composed of more species, a wider 
range of growth forms and a more perfect or at least more 
extended system of mutual adjustments and interdependence 
among species (e. g. in degrees of tolerance of shade, in 
moisture retaining moss cover, in diversity of forest floor 
species, in numbers of climbing and twining plants, in rich- 
ness of forest floor fungi and wood destroying fungi, in sym- 
biotic relation between fungi and the roots of higher plants, 
in the indispensable role of soil bacteria). See page 163 for 
further discussion of the climax forest. 
4. As to the Static Character and Nutrition Relations of 
the Green Plant—Especially of the Cormophytic Plant. 
The strategic fact which determines both the ground-gain- 
ing or invading power of vegetation as well as the effect it 
