27 
but there is a thick ground cover of mosses and a layer of humus about 
4 inches thick. These facts indicate that the old timber was burned in 
such a way as to kill the trees without injuring the humus and ground 
cover. A few aspens came in with the young spruces following the fire, 
but all except the most hardy were crowded out by the rapidly growing 
conifers. 
A piece of woods south of Pine lake has in recent years suffered a 
burn which did not seriously injure the ground cover. There was form- 
erly a mature jackpine forest with some aspens in it, as indicated by the 
windfalls. The young trees now coming into the area are aspen and 
spruce, the latter showing dense stands of strong trees. Evidently the 
course of the succession was not seriously affected. 
When immature jackpine woods are burned there is an immediate 
and abundant growth of seedling pines with a very few aspens. The 
pines gradually thin out with age. The ground cover is so thin in such 
a case that a ground fire does little more damage than a crown fire, since 
the soil is already rather sterile. If it burned the ground cover badly 
it would lessen the viability of seeds, but this would only slightly lengthen 
the period of its return to pine woods. 
In the case of older woods that have been badly burned by ground 
fires, notable exceptions to the normal succession of the vegetation occur. 
It is in such areas that the greatest growth of deciduous timber is found. 
The woods immediately around the Pine Lake ranger station consist 
mostly of aspens and poplars. 
The deciduous timber is of two types: the aspen woods, and the 
poplar-spruce woods. The first of these is the most abundant, and next 
to the mature spruce forest it is the thickest timber in the region. It 
also contains the greatest number of species. The aspens form a close 
stand of trees 50 to 80 feet high, and reaching 12 ‘ to 20 inches in dia- 
meter, with straight clean boles. Other occasional trees are balsam pop- 
lar Populus tacamahacca , Canada spruce, and jackpine. The pines are 
all scraggly trees that are evidently remnants of the burn. The poplars 
and spruces are all young trees coming up in the shade of the aspen. A 
distinct shrub and young tree flora is formed mainly of grey willow 
Salix Bebbiana , and sapling poplars. Other less common shrubs are 
Shepherdia canadensis , Amelanchier fiorida, Rosa aciculans, Lonicera 
glaucescens, Viburnum paucifiorum , and Symphoricarpos albus var. pauci- 
fiorus. The ground is covered with dead leaves and other plant parts, but 
there are almost no mosses and lichens. The leaf mould is 1^ to 2 inches 
thick on a sandy substratum. The primary herbaceous species is- a grass 
Elymus innovatus. It does not- form a turf, but is very common consider- 
ing its woodland habitat. About thirty species of herbaceous plants occur, 
with none in very great numbers. This seems to be a sort of common 
ground for most of the herbs "of the other forest types, but Botrychium 
Lunaria, Habenaria virdis var. bracteata, Delphinium scopulorum var. 
glaucum, Thalictrum venulosum, Lathyrus ochroleucus, Vicia americana, 
Aster junceus , and A . Bindley anus may be considered characteristic. 
Occurring in patches in the aspen woods may be found the second 
type of deciduous timber, in which balsam poplars, accompanied bv spruces, 
have superseded the aspens. A good view of this condition may be gained 
