26 
invasion of moisture-loving mosses and lichens of the woodlands. The 
common fioristic content of what might be called a mature jackpine Pinus 
Banksiana forest is as follows: 
Primary spp.: Pinus Banksiana 
Alnus crispa 
Cladonia alpestris 
Pel tig era aphthosa 
Vaccinium Vitis-idaea var. minus 
Hypnum Crista-castrensis 
H. Schreberi 
Polytrichum juniperinum 
Secondary spp. : Picea glauca (small saplings) 
Elymus innovalus 
Maianthemum canadense 
Populus tremuloides (small saplings) 
Satiz Bebbiana 
Betula papyrijera var. neoalmkana 
Geocaulon lividum 
Pulsatilla ludoviciana 
Fragaria glauca 
Rosa acicularis (small bushes) 
Shepherdia canadensis 
Epilobium angustijolium 
Cornus canadensis 
Arctostaphylos Uva-ursi 
Galium boreale 
Linnaea borealis var. americana 
Viburnum pauciflorum (small bushes) 
Campanula rotundifolia 
The scattered secondary species indicate the trend toward mesophy- 
tism above noted. The young spruce trees are thriving in the shade of the 
pines and in the soils w r hich, by the accumulation of vegetable remains, 
are increasing their water-holding capacity and their supply of nutrient 
materials. As the spruce trees grow to such a size that they can shade 
the now moister ground, the pines fail to germinate. * A common forest 
type on the uplands is one in which there is a vigorous stand of young 
spruce trees with a growing mat of mosses beneath them, and scattered 
among them a few ancient pines with great arching branches that are 
leafless except at their very tips. Semi-decaved logs in such woods 
prove to be those of the former pine forest. Old fallen trees in spruce 
forests of the more mesophytic type are of spruces, indicating the rela- 
tive perpetuity of this type. 
Extensive forest fires have seriously modified vast areas of Wood 
Buffalo park, so that the resulting deciduous or partly deciduous wood- 
lands are among the commonest types of vegetation. The amount of 
influence exerted by a fire depends upon the nature of the fire and upon 
the stage of development of the timber burned. A crown fire, driven 
by a high wind, burns the leaves of the conifers and kills the trees, but 
does not greatly affect the ground layer. In such a case the timber 
seems to return to its former condition without much delay. On a 
sandy hill at the east side of Pine lake there is a heavy spruce forest 
with occasional large aspens Populus tremuloides in it. There are a 
great many old windfalls that show evidence of having been killed by fire, 
t 
