=~] 
Forest Development in the Adirondacks 2 
previously stated much of this is approximately pure black 
spruce stand, the tamarack being scattered and often infre- 
quent. Arbor vitae occurs infrequently only in the western 
section of the bog. With the arrival of this closed stage of 
young forest the sphagnum-shrub asscciation has been very 
largely suppressed or at least dominated. The diversified bog 
surface with its mounds and depressions and its loose spongy 
texture becomes leveled and more compact. At this stage few 
other species of the conifer association have xppeared. It is 
rather the phase of elimination of the species of the sphagnum- 
shrub association. This in time passes into 
(c) The Closed Stand of Older Black Spruce-Tamarack Forest. 
This may be regarded as the culminating phase of the 
purely bog series of associations. Figure 19 shows a remnant 
of a rather old stand of black spruce and tamarack in which 
tamarack has made the better growth. Very often this stage 
will be represented by a pure spruce association. At this 
stage well recognized forest conditions have been established 
with respect to the forest canopy, to the semi-twilight zone 
beneath it (now a more roomy space with boles partially or 
wholly self pruned to a height of ten feet and upwards) and 
with respect to the bog surface now to be designated as the 
forest floor. A fairly uniform pure stand of black spruce over 
fifty years old presents instructive features in this connection. 
Bog shrubs have been very largely suppressed though tall 
spindling shrubs of Ledwm groenlandicum and Kalmia angus- 
tifolia are scattered here and there while Vaccimwm canadense 
almost or wholly wanting in the open bog is relatively frequent 
in the forest shade. The floor is covered by a level, deep 
carpet of living sphagnum — chiefly Sphagnum magellanicun: 
which makes a very rapid spindling growth that quickly covers 
the annual fall of spruce twig and needles, these lying as 
imbedded layers in the dead sphagnum. ‘The log of a fallen 
spruce some six inches in diameter was also thus quickly 
covered. Slight elevations of the forest floor —fallen logs, 
stumps and the broadened bases of living trees —are becoming 
occupied by forest floor species commonly found in balsam 
