Development of the Vegetation of New York State 139 
and certain annual plants. More generally, the country 
burned over is covered by a growth of aspen (Populus 
tremuloides), fire cherry (Prunus pennsylvanica and oc- 
easional birch (Betula lutea) and large toothed poplar 
(Populus grandidentata). 
The ease of Dibble Mountain in the Catskills is instructive 
in this matter of the development of vegetation on exposed 
rock.. The fairly flat top of this mountain was lumbered 
for red spruce some 15 or 20 years ago. Subsequently a 
fire or fires cleared the summit of practically everything in- 
eluding a rich, deep blanket of organie debris. Stages in 
succession moving toward forest recovery include minute 
algae, lichens and especially moss mats of Polytrichum be- 
ginning especially at moist fissures. Fire weed (Chamae- 
neriton (Hpilobium) angustifolium (L.) Scop.), bristly sar- 
saparilla (Aralia hispida Vent.) and other herbs, and sparse 
grasses and sedges get a foothold in the fissures or older mats 
of moss. The dominant cover at this time is made up of the 
usual fire cherry and aspen growth, with a boreal birch 
(Betula cordifolia Regel = Betula alba var. cordifolia of 
Fernald) and the encroaching original forest as seedlings and 
young saplings of red spruce and balsam. The presence of 
seams and pockets, the latter due to the presence of the frac- 
tured summit rock, are factors in this relatively rapid re- 
covery. 
The North slope of Dibble mountain which if stripped of 
forest cover and organic soil blanket would present a steep 
talus of rock fragments, many of huge dimensions, with finer 
debris and weathered products filled in among them, shows 
a climax forest cover of our zone D type with less maple and 
yellow birch and more balsam, spruce and mountain ash 
above 3,000 feet but just the reverse proportions at lower 
elevation. The presence of such a forest with its constant 
soil moisture conditions stands in great contrast to those 
slopes which have been denuded and thrown back into a 
xerophytic condition. This case represents the conditions 
and outeome of vegetation development for a large amount of 
territory in the State namely, the rougher hill and mountain 
