226 BOTANICAL GAZETTE [MARCH 
resulting therefrom; the presence of more or less humus at the 
beginning (it rarely happens that fire destroys every vestige of 
organic matter, and even a very small quantity in a rock crevice 
is of great assistance in hastening the establishment of vegetation) ; 
frequent protection from the drying and mechanical effects of wind; 
TABLE VI 
Species Climax forest Burn 
PICS ASAIO oe i eine ois ss 65 I 
Betula alba var. papyritera, <2... 2. i ss 6 117 (sprouts) 
Picea oo ee ee eee Se I a 
Da re eS oa res 13 ae 
Populus reeculoeiee eet Pewee Cok a 16 
PEERS CONACERSIS ©) 55 5 oa eh oe vcs 14 ne 
WiburiiiD DAUCHOMUI. es ss I I 
Rubus idaeus var. aculeatissimus......... 5 74 
Wee DUCICAMNS Cf oh ee eke bea es 21 
MME MO eg a ee ev ons es 21 
Werte BERICOG os si ne seins 13 
Linnaea borealis var. americana.......... 6 30 
in MAG pian vod oes Ss 2 
Epilobium angustifolium................ 806 
AUepnals MAreAritaces ..........0.55 421 
Maianthemum i ae et ree a ag 312 
Calamagrostis canadensis............... 83 
* Frequent in most parts of climax forest. 
presence of a large body of invaders ready to advance from all 
directions. All these modifying influences tend to hasten the 
progress of the succession. Areas where fire has exposed the bare 
rock are found principally upon the tops of ridges, since the soil 
in such places is usually both shallow and dry, and whatever remains 
after the fire is washed away to lower levels. 
III. Effect of fire upon the xerophytic and bog forests 
When the jack pine—black spruce forest is burned, much of the 
humus is apt to be destroyed also, as the soil is commonly thin and 
dry. A few observations indicate that this type often succeeds 
itself. The pine grows faster and so for a number of years is the 
dominant tree. In one burned locality was found an open growth 
of pines 4-7 m. high, even-aged, averaging 28 years. Beneath 
